MSC.Nastran 2005 r3 Release Guide

MSC.Nastran 2005 r3

Release Guide

CorporateMSC.Software Corporation2 MacArthur PlaceSanta Ana, CA 92707 USATelephone: (800) 345-2078Fax: (714) 784-4056

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DisclaimerMSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice.

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C o n t e n t sMSC.Nastran 2005 r3 Release Guide

MSC.Nastran 2005 ase Guide

Table of Contents iiiPreface ix

List of MSC.Nastran Books x

Technical Support xi

Internet Resources xiv

1 Overview of MSC.Nastran 2005 r3

Overview 2Nonlinear Analysis 2Numerical Enhancements 2Elements 2Dynamics and Superelements 3Aeroelasticity 3Optimization 3Summary of MSC.Nastran Quick Reference Guide Changes 3List of MSC.Nastran Documents Released with MSC.Nastran 2005 r3 4

2 Nonlinear Analysis

MSC.Nastran Implicit Nonlinear - SOL 600 8Introduction 8Activating the CASI Interactive Solver 9Activating Large Displacement 10New Bulk Data Entries 14Brake Squeal Calculation 14Inertia Relief 17User Subroutines 19

3 Numerical Enhancements

New Iterative Solver Option 22Introduction 22Benefits 22

r3 ReleTable of Contents

MSC.Nastran 2005 r3 Release Guide

iv

Method and Theory 22Inputs 23Outputs 23Guidelines and Limitations 24Demonstration Example 24Example Input Data 24Example Output 29

MDACMS Enhancements 31Background 31Summary 31New FMS Command: MEMLIST 31New Module: RESMOD 32Option P1 = ‘ATBC’ 34Option P1 = ‘MPART’ 34Option P1 = ‘LININD’ 35Option P1 = ‘LDSWEEP’ 36Option P1 = ‘USWEEP’ 37

MPYAD Method 1 Enhancement 38Example 38Problem Definition: 38Machine Resources 38

Improved Robustness in the Lanczos Method 39

MLDMP in Solution 111 (Pre-Release) 40User interface 40Case Study 40

4 Elements

Three-Node Beam Element 44Introduction 44Benefits 44Input 44Guidelines and Limitations 45Formulation 47Output 49Example 51

CWSEAM Connector Elements 54Introduction 54Inputs 54Error Conditions for the CWELD and CWSEAM Elements 59

vContents

Example – A Symmetric Hat Profile (cwseam_hut.dat) 63

Line Interface Element 65Introduction 65User Interface 66Example and Results 71

Arbitrary Beam Cross-Section 74Introduction 74Benefits 74Inputs 74Output 76Guidelines 78Limitations 78Example 78

5 Dynamics and Superelements

Efficiency Enhancements to MTRXIN Module for Handling DMIG Data 90

Enhancements to BSETi/BNDFIXi and CSETi/BNDFREEi Bulk Data Entry Processing 91

Enhancements to MATMOD Module Option 16 92Introduction 92Usage 93Example 93Enhancements to MATMOD Module 93

Enhancements to External Superelement Usage Via EXTSEOUT Case Control Command 97

Introduction 97Addition of Options to ASMBULK Keyword 97Addition of New FSCOUP Keyword 98Addition of New DMIGSFIX Keyword 98Automatic Numbering Scheme for Q-set DOFs Via AUTOQSET Usage 99Automatic Availability of Output for Boundary Points and PLOTEL Points of External Superelements in Assembly Run 100New MATDB Option As Equivalent to Current MATRIXDB Option 100

Changes to Rotordynamic for MSC.Nastran 2005 r3 101Additional Damping Options for Rotors 101Squeeze Film Damper as Nonlinear Force 106Squeeze Film Damper as Nonlinear Element 107Gyroscopic Terms Added to Aero Solution Sequences 109


vi

Campbell Diagrams 109Rotor Forward and Backward Mode Identification 110Rotor Mode Tracking 113Comments 113Modified Basic Equations Used in Rotordynamics 114Frequency Response 115Complex Modes 117Nonlinear Transient Response 119

6 Aeroelasticity

Monitor Points 122Introduction 122Benefits 123Input 123Output 124Examples 127Guidelines and Limitations 127

Spline6/7 129Introduction 129Benefits 130Input 130

Combination of Controllers/User Input Loads Enhancements 131Introduction 131Benefits 131Input/Output 132Guidelines and Limitations 132Examples (aelinka.dat, aelinkb.dat,i3fusa.dat,aepload4.dat,fusae.dat) 132

Separate Rigid and Flexible Aero Meshes 133Introduction 133Benefits 133Input 133Output 133

Miscellaneous Aeroelastic Enhancements 135Revision in the Aerodynamic Splining to the Structure 135Flutter Analysis with Singular Mass Matrices 135

7 Optimization

Topology Optimization with Manufacturability Constraints 138Introduction 138

viiContents

Benefits 138Input 139Guidelines and Limitations 142

Example 1 – MBB Beam Baseline (topex3.dat) 143

Example 2 - MBB Beam with Minimum Member Size (topex3a.dat) 145

Example 3 - MBB Beam with Symmetric Constraints (topex3b.dat) 146

Example 4 - A Torsion Beam with Extrusion Constraints (topex5.dat) 148

Example 5 - A Torsion Beam with One Die Casting Constraints (topex5a.dat) 150

Example 6 - A Torsion Beam with Two Die Casting Constraints (topex5b.dat) 152

Revised Optimizer Options 154Introduction 154Benefits 154Input 154Output 156Guidelines and Limitations 156

Supporting Trust Region in SOL 200 for Adaptive Move Limits 157Introduction 157Benefits 157Theory 157Input 159Outputs 160Guidelines and Limitations 161Examples 161

Support of Analysis Model Value Overriding Design Model Value 164Introduction 164Benefits 164Input 164Output 164Example 164Guidelines and Limitations 165

8 Miscellaneous Enhancements

Export of Static Loads 168Introduction 168


viii

Benefits 168Input 168Output 169Examples (TPL: exptld/imptld, sysmod/fbody, sfsw/ffsw) 169Guidelines and Limitations 170

Enhanced Participation Factor Results 171Introduction 171Benefits 171Theory 172Input 174Guidelines 177Limitations 177Example--Acoustic Analysis of a Cabin 178

Total Strain Energy Output for Defined SETs 183Introduction 183Inputs 183

Model Checkout Procedures - Method to Vary Material Properties 186Introduction 186Benefits 186Method and Theory 186Inputs 186Outputs 187Guidelines and Limitations 187Demonstration Example 187Example Input Data 187Example Output 192

9 Upward Compatibility

Summary of DMAP Module Changes from MSC.Nastran 2005 r2 to MSC.Nastran 2005 r3 196

DMAP Module Changes 196

The 2005 New Template

Preface

List of MSC.Nastran Books

Technical Support

Internet Resources


x

List of MSC.Nastran BooksBelow is a list of some of the MSC.Nastran documents. You may order any of these documents from the MSC.Software BooksMart site at www.engineering-e.com.

Installation and Release Guides

Installation and Operations Guide

Release Guide

Reference Books

Quick Reference Guide

DMAP Programmer’s Guide

Reference Manual

User’s Guides

Getting Started

Linear Static Analysis

Basic Dynamic Analysis

Advanced Dynamic Analysis

Design Sensitivity and Optimization

Thermal Analysis

Numerical Methods

Aeroelastic Analysis

Superelement

User Modifiable

Toolkit

Implicit Nonlinear (SOL 600)

xiPreface

Technical SupportFor help with installing or using an MSC.Software product, contact your local technical support services. Our technical support provides the following services:

• Resolution of installation problems• Advice on specific analysis capabilities• Advice on modeling techniques• Resolution of specific analysis problems (e.g., fatal messages)• Verification of code error.

If you have concerns about an analysis, we suggest that you contact us at an early stage.

You can reach technical support services on the web, by telephone, or e-mail:

Web Go to the MSC.Software website at www.mscsoftware.com, and click on Support. Here, you can find a wide variety of support resources including application examples, technical application notes, available training courses, and documentation updates at the MSC.Software Training, Technical Support, and Documentation web page.


xii

m.com

Phone and Fax

Email Send a detailed description of the problem to the email address below that corresponds to the product you are using. You should receive an acknowledgement that your message was received, followed by an email from one of our Technical Support Engineers.

United StatesTelephone: (800) 732-7284Fax: (714) 784-4343

Frimley, CamberleySurrey, United KingdomTelephone: (44) (1276) 67 10 00Fax: (44) (1276) 69 11 11

Munich, GermanyTelephone: (49) (89) 43 19 87 0Fax: (49) (89) 43 61 71 6

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Madrid, SpainTelephone: (34) (91) 5560919Fax: (34) (91) 5567280

MSC.Patran SupportMSC.Nastran SupportMSC.Nastran for Windows SupportMSC.visualNastran Desktop 2D SupportMSC.visualNastran Desktop 4D SupportMSC.Dytran SupportMSC.Fatigue SupportMSC.Interactive Physics SupportMSC.Marc SupportMSC.Mvision SupportMSC.SuperForge SupportMSC Institute Course Information

[email protected]@[email protected]@mscsoftware.comvndesktop.support@mscsoftware.commscdytran.support@[email protected]@[email protected]@mscsoftware.comscsuperforge.support@[email protected]

xiiiPreface

TrainingThe MSC Institute of Technology is the world's largest global supplier of CAD/CAM/CAE/PDM training products and services for the product design, analysis and manufacturing market. We offer over 100 courses through a global network of education centers. The Institute is uniquely positioned to optimize your investment in design and simulation software tools.

Our industry experienced expert staff is available to customize our course offerings to meet your unique training requirements. For the most effective training, The Institute also offers many of our courses at our customer's facilities.

The MSC Institute of Technology is located at:

2 MacArthur PlaceSanta Ana, CA 92707Phone: (800) 732-7211 Fax: (714) 784-4028

The Institute maintains state-of-the-art classroom facilities and individual computer graphics laboratories at training centers throughout the world. All of our courses emphasize hands-on computer laboratory work to facility skills development.

We specialize in customized training based on our evaluation of your design and simulation processes, which yields courses that are geared to your business.

In addition to traditional instructor-led classes, we also offer video and DVD courses, interactive multimedia training, web-based training, and a specialized instructor's program.

Course Information and Registration. For detailed course descriptions, schedule information, and registration call the Training Specialist at (800) 732-7211 or visit www.mscsoftware.com.


xiv

Internet Resources

MSC.Software (www.mscsoftware.com)

MSC.Software corporate site with information on the latest events, products and services for the CAD/CAE/CAM marketplace.

Simulation Center (simulate.engineering-e.com)

Simulate Online. The Simulation Center provides all your simulation, FEA, and other engineering tools over the Internet.

Engineering-e.com (www.engineering-e.com)

Engineering-e.com is the first virtual marketplace where clients can find engineering expertise, and engineers can find the goods and services they need to do their job

CATIASOURCE (plm.mscsoftware.com)

Your SOURCE for Total Product Lifecycle Management Solutions.


Ch. 1: Overview of MSC.Nastran 2005 r3 Ch. 1: Overview of MSC.Nastran 2005 r3Key Highlights

for MSC.Nastran 2005 r3

1 Overview of MSC.Nastran 2005 r3

! Overview


2

OverviewThe MSC.Nastran 2005 r3 release brings major new features and enhancements for enterprise computing in the areas of high performance computing, nonlinear analysis, assembly modeling, optimization, rotor dynamics and aeroelasticity.

Nonlinear Analysis• MSC.Nastran Implicit Nonlinear - SOL 600 – Enhancements have been made to greatly improve

the performance and capabilities of MSC.Nastran’s implicit nonlinear solution. These include more robust data exchange, faster contact (three to six-fold CPU time improvements), auto SPC and MSET, inertia relief, an improved out-of-core solver, expanded results support, automated brake squeal computations, improved fixed time stepping, and improved user subroutine support.

Numerical Enhancements• Iterative Solvers – There is now a new iterative solution for static analysis. Also, significant

performance improvements along with reduction in I/O requirements have been achieved in the ACMS solution.

Elements• Arbitrary Beam Cross-Section – The interface for describing arbitrary cross-section shapes for

bar and beam elements has been enhanced to include a cross-section outline display, stress data recovery and design optimization. The profiles can now be optimized using SOL 200. Stress recovery includes both torsion and shear terms.

• Line Interface Element – You can now connect dissimilar meshes along edges. A set of MPC (multipoint constraint) equations are internally generated to enforce the compatibility of displacements and rotations across the interface. This feature is particularly useful for global-local modeling, where a local fine mesh is required in a particular region due to high stress gradients.

• CWSEAM Connector ElementsCWSEAM Element - A seam element to connect surface patches is now available. This element extends the existing CWELD and CFAST connector elements. The seam weld is defined by selecting two surface patches by their property IDs and specifying the width and the thickness of the seam. Extensive error checking and user diagnostics include detection of missing connections for CWSEAMs, defined across corners and cutouts.RBE2GS Element – This element generates internal RBE2 element connecting a grid point pair closest to a user-defined search grid point. You can exclude optional grids within search radius.

• Three-Node Beam Element – A general spatial three-node beam element has been developed for linear static, modal, dynamic, and buckling analyses. The element is implemented as a curved one-dimensional Timoshenko beam element with initial curvatures and pre-twist. The cross-sectional warping effect is also included.

3CHAPTER 1Overview of MSC.Nastran 2005 r3

Dynamics and Superelements• Rotor Dynamics – With this release we introduce a new general displacement and speed

dependent nonlinear element for rotor bearings and a nonlinear squeeze film damper element. Also, we support the gyroscopic terms in aero solution sequences, non-linear harmonic response, and an easier Campbell diagram to identify rotor modes and track across subcases.

• Enhancements to External Superelement Usage Via EXTSEOUT Case Control Command – Several improvements have been made to external superelement (SE) usage employing the EXTSEOUT feature with a view to enhancing user convenience and flexibility. These include, the ability to: (a) specify suffixes for DMIG matrices resulting from the use of the DMIGPCH option, (b) get output for the boundary points and PLOTEL points of an external SE in the assembly run regardless of the output requests in the external SE creation run, and (c) have control over the Q-set or generalized degrees of freedom (DOFs) of an external SE in the assembly run.

Aeroelasticity• Monitor Points - We have added support for monitor points, including a MONPNT2 that selects

a specific element response for output, a MONPNT3 that outputs an integrated load on a structural subcomponent, and a MONDSP1 that provides averaged displacement components. All of these are available in SOLs 101 and 144, while SOL 146 supports MONPNT1 and MONDSP1.

• Export and Import of Loads -Two methods have been provided to extract loads from an analysis for import into another analysis. The EXPORTLD Case Control command supports the creation of a datablock that contains the external load of a user specified set of grids. Alternatively, one can export a “free-body” load based on the grid point forces of a user specified subcomponent. Both of these loads can be imported into a subsequent analysis via dblocate commands, and included in the external load specification.

Optimization• Topology Optimization with Manufacturability Constraints – This release supports

manufacturing constraints including casting (draw direction), extruding, and symmetry to ensure that the optimal size and shape determined for the given set of loads and boundary conditions conforms to manufacturing.

Summary of MSC.Nastran Quick Reference Guide ChangesChanges to the MSC.Nastran Quick Reference Guide to accommodate developments, improvements, and added functionality for MSC.Nastran 2005 r3 are substantial. The following tables categorize these changes according to the section of the QRG affected.


4

List of MSC.Nastran Documents Released with MSC.Nastran 2005 r3Along with this Guide, the following documents are updated for the MSC.Nastran 2005 r3 release.

MSC.Nastran Version 2005 r2 Release Guide Addendum

Input Changes

Section New Modified

nastran Statement

NASTRAN

Executive Control

MODEL_CHECK SOL 600,ID

Case Control

AERCONFIGEXPORTLDFBODYLDMONITOR

PFGRIDPFMODEPFPANELSETP

ADAMSMNFBCONTACTEXTSEOUTDRSPAN

Bulk Data ACCBJOINBRKSQL# CBEAM3CINTCCORD1RXCORD2RXCORD3RXCSPRCWSEAMFBODYLDFBODYSBEGBAGMATD005MATD009MATDS01MATDS02

MATRIGMONDSP1MONPNT1MONPNT2MONPNT3PBEAM3PBEAMDPLOADB3PSHELLDPSPRMATPWSEAMRBE2ARBE2DSPLINE6SPLINE7SUPORT6#SWLDPRMTEMPB3TMPSETTTEMPUSRSUB6#WALLGEO

AEFORCEAELINKBCPROP#BCTABLE#BNDFIXBNDFIX1BNDFREEBNDFREE1BSETBSET1BSURF#CELAS2DDESVAR

DRESP1IPSTRAIN#ISTRESS#ITERMATD126MATHED#MATORT#MBOLTUS#NLSTRAT#PBARLPCONVRESTART#TSTEPNL

Parameters HEATCMD#MARCBATCH#MARCBUSH#MARCITER#

MARCCBAR#MARCRCID#MARGPFOR#MEXTRNOD#MLSTRAIN#MRBEPARM,#MRCOMPOS#MRCONVER#MRPSHELL#MSPEEDOU#

MARCAUTO#MARCOTIM#MARCPINN#MARCPOST#MARCRBE3#MARCSAME#MARCSLHT#

MARCSOLV#MARCUSUB#MRESTALL#MRMAXMEM#MRSPAWN2#MRSPEEDSE#MRTABLS2#MRTABLS1#

5CHAPTER 1Overview of MSC.Nastran 2005 r3

MSC.Nastran Quick Reference Guide

MSC.Nastran DMAP Programmer’s Guide

MSC.Nastran Installation and Operation’s Guide

MSC.Nastran Design Sensitivity and Optimization User’s Guide

MSC.Nastran Implicit Nonlinear (SOL 600) User’s Guide


6


+ Ch. : h0title Ch. 2: Nonlinear Analysis Ch. 2: Nonlinear Analysis

2 Nonlinear Analysis

! MSC.Nastran Implicit Nonlinear - SOL 600, 8


8

MSC.Nastran Implicit Nonlinear - SOL 600

IntroductionThis section documents the changes and additions to SOL 600 between MSC.Nastran 2005 r2 and MSC.Nastran 2005 r3. The following new capabilities have been added:

• Reduced memory for many SOL 600 analyses is triggered by PARAM,MARCOOCC. There are two effects when selecting this parameter:

• The memory used for decomposition is used for other purposes as well, which reduces memory required, but may result in an increase in I/O time.

• When using SOLVER type 8, the minimal amount of memory will be used.

• Reduced memory for analyses when composites or multiple element types are used.

The storage of element data quantities like stresses and strains has been modified. Previously, the amount of memory allocated per element was the maximum required for any element type. Thus there was a memory overhead in cases with different element types, or shells with different number of layers. In this release, the element data is dynamically allocated based upon element groups, where an element group contains one unique element type and material type. No new input is required because of this change.

The amount of memory saved with the new element data storage is model dependent. There is no savings in memory if a homogeneous model with one element type is used. Extreme cases would be when there are only a few elements that require a large amount of memory, for example a model with a few 20-grid point CHEXA with the remainder of the mesh being 4-grid point CTETRA.

In one example with a combination of 10,000 composite CHEXA and 80,000 CTETRA, which had several composite groups, with a maximum of 30 layers, the memory required for element storage was reduced from 11.9 Gbytes to 0.75 Gbytes. An engine model that had a total of 310,000 elements containing a combination of 20-node CEXA, 8-node CHEXA, 10-node CTETRA, 4-node CTETRA and CQUAD4 has achieved a memory reduction from the prior 3.76 GBytes to 0.86 Gbytes.

• The amount of memory has been reduced when a large number of MPC, RBE2, and RBE3 are in the model. The memory usage was especially acute when some RBEs have a large number of grid points. Furthermore the computational time associated with the application of the MPCs has been reduced.

• The value on the memory given on the PARAM,MARCMEM,value is no longer used in the

same way as in previous versions. Instead of setting the 2nd field of the SIZING entry, it now sets –ml value on the command line where the integer value entered is in Mbytes. For most analyses, the value entered can be smaller than what was needed for previous versions.

• There are two new parameters for allocating the memory use, the first PARAM,MRALLOCG,value; allocates the initial amount of General memory. The value specified is in megabytes. In this release General memory is used for material property data, boundary condition data, overhead, and the assembly of the global stiffness matrix (except CASI

9CHAPTER 2Nonlinear Analysis

solver). The General memory is also used for Solver 0 and Solver 4 (NLSTRAT,ISOLVER). The second parameter PARAM,MRALLOCS,value’ allocates the initial memory for the decomposition of the global stiffness matrix for Solver 8 (multifrontal direct solver). This is often useful to avoid reallocation of memory which occurs in deformable-deformable contact. For parallel processing the amount specified is the total for the job. It is divided by the number of domains used for each domain.

Activating the CASI Interactive Solver• The CASI iterative solver was added; which can be activated by the NLSTRAT ISOLVER entry.

Currently, two preconditioner are available, a primal and standard preconditioned, types 0 and 1, respectively. The primal preconditioner is the default and is recommended for ill-conditioned problems. If a non-positive definite matrix is encountered (such as in a buckling analysis), the solver automatically switches to a direct solver. In this release this solver may not be used for Herrmann elements, where the Lagrange multiplier is at the corner node, such as the higher order elements or the triangular and tetrahedral elements. This solver should also not be used with the gap element.

As an example of the improved performance with this solver an engine block with 2.2 million degrees of freedom was analyzed with the following normalized results.

• The computational times associated with running jobs in parallel has been reduced. This reduction is both in the time associated with creating the domains in during the solution process. For poorly conditioned models, the improvements have been as large as a factor of two.

Memory has been reduced for analyses run in parallel.

• The number of contact bodies has been increased from 99 to 999

• AUOTMSET has been added to SOL 600 This is triggered by PARAM,AUTOMSET,YES in the bulk data. If the PARAM,MARMPCHK is also included in the model, it will be ignored.

• Inertia Relief has been added. The SOL 600 capability exceeds that available in other MSC.Nastran solution sequences using new Bulk Data entry, SUPORT6. One method is available for MSC.Nastran 2005 r3.

• The “support” method may be used to specify which degrees of freedom should be “supported” for each body. This is an extension of the PARAM,INREL,1 method and may use fewer computer resources than the eigenvalue method for some models.

Solver TypeNormalized

Solution Time

2 0.785

8 1.0

9 0.174


10

Inertia Relief may be employed on a subcase-by-subcase basis and can be removed if all previously unsupported bodies merge into the main body (which is supported) either all at once or gradually.

• PSHELL with the same bending-membrane coupling as in other solution sequences has been added into the 2005 r3 beta release. This will allow you to analyze composite structures using the smeared approach (such as done in other MSC.Nastran solution sequences) or through-the-thickness integration (which is more accurate and presently the only way to analyze composite structures) will be offered. If material nonlinearity occurs in the element, then the PSHELL smeared approach should not be used. The choice is activated by using PARAM,MRPSHELL,1.

• A new option named DMIG-OUT is available in the 2005 r3 release. This capability will allow the stiffness, differential stiffness and mass matrices (assembled or element-by-element) to be output for selected output times or at the end of each nonlinear subcase for use in other analyses. This is a less expensive procedure, than using the Bulk Data entry, MDMIOUT (which creates a superelement), but results in a much larger matrix.

• A preliminary version of Grid Force Balance is available. The output is available in the op2, xdb, f06 and punch files and is triggered by Case Control GPFORCE( )=ALL as well as PARAM,MARGPFOR

Activating Large Displacement• A simplified procedure is available for activating large displacement – large strain analysis, by

using the PARAM,MLSTRAIN. This option will automatically select the best formulation based upon the individual element type and material model. It effectively replaces the use of PARAM,LGDISP; PARAM, MRUPDATE; PARAM, MRFINITE and PARAM,MARCDILT for most simulations. Internally the following formulations are used.

• The Gent and Arruda Boyce models may now be used with plane stress, shell and membrane elements

Large Strain Option

element type / material model

1-d plane stress or membranes or shell elements

plane strain or axisymmetric, or 3-d, displacement form.

plane strain or axisymmetric, or 3-d, Herrmann form

conventional elastic-plastic

Updated Lagrange Additive Plasticity No Finite Strain

Updated Lagrange Additive Plasticity Includes Finite Strain

Updated Lagrange Additive Plasticity Includes Finite Strain Utilized Constant Strain

Updated Lagrange Multiplicative Plasticity Includes Finite Strain

Mooney, Ogden, Gent or Arruda-Boyce

Total Lagrange Total Lagrange Updated Lagrange Updated Lagrange

Foam Total Lagrange Total Lagrange Updated Lagrange Updated Lagrange, Incompressibility Neglected


• The NLELAST option on the MATS1 is now supported in SOL 600 as in the other solution sequences (106, 129, and 400). It is more general in that it may be used will all structural element types (except the shear panel).

• A new higher order tetrahedral element is available which has improved behavior in bending. To activate this element, use the PARAM,MRALIAS,127184 to switch the element formulation from SOL 600 element type 127 to 184.

• The method for updating the thickness of shells and plane stress elements has changed if the PARAM,MRFINITE or PARAM,MLSTRAIN. This is activated using: PARAM,MRV09V11,1

• The in-plane shear behavior of the CQUAD 4 element using reduced integration has been improved. This element technology is invoked by using PARAM,075140. This is activated using: PARAM,MRV09V11,1

• Dissimilar meshes of shell elements may now be “glued” together using fully moment carrying capability of the contact glue option. This is activated using the BCTABLE option.

• A new parameter has been added when using SOL 600 analysis. When relevant, this generally results in improved behavior, but will lead to some differences in results with the previous release. This is activated using PARAM,MRV09V11,value, where

Note that the above features are only used for certain problems. Even though all are included with the default option, they have no effect for problems that do not use them. For example, feature,5801 has no effect on models that do not use SOL 600 element type 140, feature 601 has no effect on models that do not have contact.

• The speed of the t16op2 results translator has been increased by a factor of 4 or more for large models. The speed increase is triggered using PARAM,MSPEEDOU,1

-1 Do not add the features

1 Add the following features (default):

feature,4703 to speed up DDM jobs (for 1-processor jobs, it has no effect).

feature,5701 to disable old rigid rotation checking which was too stringent

feature,601 to improve contact

feature,5301 to improve deformable-deformable contact

feature,3201 to improve contact friction types 6 and 7

feature,5601 to improve thickness updating when the updated Lagrange method is used

feature,5801 to improve in-plane bending of SOL 600 element type 140

feature,6001 to improve concrete cracking analysis


12

• Translation speed has increased for beam and shell type elements (in addition to the previous speed enhancements for solid elements) by using PARAM,MSPEEDSE,2 (or 3). The speed increase varies from model to model but can be as great as a factor of 4-10 for some models.

• A new Bulk Data entry for brake squeal named BRKSQL is available which replaces several parameters and MARCIN entries previously used. With the entry, new capabilities are also introduced. It is now possible to determine the unstable brake squeal roots using MSC.Nastran’s complex eigenvalue solver and unsymmetric friction stiffness matrices for an undeformed structure or after a nonlinear subcase. Brake squeal analysis for SOL 600 is accomplished by starting a primary MSC.Nastran job (as usual) which spawns SOL 600 to calculate the unsymmetric friction stiffness matrices either at the beginning or end of a nonlinear subcase, then spawning a second MSC.Nastran job to calculate the complex eigenvalues. Unstable roots indicate potential brake squeal. They are designated by positive real roots and negative damping in the f06 output file. See the BRQSQL entry from more details and the attached example.

• A new fixed-time stepping approach has been added which avoids some convergence problems with AUTO LOAD particularly for multiple subcases. AUTO LOAD is still available but the new approach is recommended particularly for multiple subcases. The available methods are selected using PARAM,MARCITER,N where N is the number of fixed time steps desired.

• MSC.Nastran SOL 600 now uses the same compilers on all systems. This allows user subroutines to be employed on all systems. For Windows and Linux, the Intel compiler is now used. Previously, the Digital Visual Fortran and PFG Fortran compilers, respectively, were used. Only the Intel versions are delivered with MSC.Nastran.

• User subroutine support has been added through Bulk Data entry, USRSUB6

• The SOL 600,ID executive control statement has been revised to add some clarifying remarks

• The Case Control BCTABLE text has been clarified

• The following new Bulk Data entries have been added for SOL 600 (see next section for a description of each new entry):

• BRKSQL (Brake Squeal)

• SUPORT6 (Inertia Relief for SOL 600)

• USRSUB6 (User subroutines for SOL 600)

• The following Bulk Data entries have been revised or additional capabilities added:

• RESTART (Shared with SOL 700, items for SOL 700 were added)

• NLSTRAT (CASI solver, rigid rotation control added)

• IPSTRAIN (text clarified)

• IPSTRESS (text clarified)

• BCPROP (text clarified)

• MBOLTUS (Extraneous variables removed)

• MATHED (text clarified)

• MATORT (defaults change to zero)

• The following parameters have been added


• MARCITER

• HEATCMD

• MSPEEDOU

• MRCONVER

• MEXTRNOD

• MARCBUSH

• MRCOMPOS

• MRBEPARM

• MARBATCH

• MARCCBAR

• MARCRACC

• MARCRCID

• MRPSHELL

• MARGPFOR

• MLSTRAIN

• MARCRADD

• MRV09V11

• The following parameters have been revised to add options, clarify text or change defaults

• MARCSOLV

• MARCRBE3

• MARCOTIM

• MARCSLHT

• MARCPOST

• MARCAUTO

• MARCGAUS

• MRMAXMEM

• MRTABLS1

• MRTABLS2

• MARCUSUB

• MRSPAWN2

• MARCPINN

• MRESTALL

• MARCOPP2

• MSPEEDSE


14

• MARCSAME

• The following parameter has been removed:

• MARNOT16

New Bulk Data EntriesA detailed description of each new Bulk Data entry is given below:

Brake Squeal Calculation

Specifies data for brake squeal calculations using SOL 600.

Format:

Example:

BRKSQL Specifies data for Brake Squeal Calculations using SOL 600

1 2 3 4 5 6 7 8 9 10BRKSQL METH AVSTIF FACT1 GLUE ICORD

R1 R2 R3 X Y Z

NASCMD

RCFILE

BRKSQL 1 5.34E6 1.0 1.0

0.0 0.0 1.0 2.0 3.0 4.0

tran

nastb


Field Contents

METH Method flag corresponding to the type of brake squeal calculations to be performed. (Integer, Default = 1)

0 = Perform brake squeal calculations before any nonlinear analysis has taken place.

1 = Perform brake squeal calculations after all nonlinear load cases.

AVSTIF Approximate average stiffness per unit area between the pads and disk. This value is also known as the initial friction stiffness in the MSC.Marc Volume C documentation. AVSTIF can be obtained by either experiment or numerical simulation. A larger value of AVSTIF corresponds to a higher contact pressure, which usually results in more unstable modes. (Real; no Default; required field)

FACT1 Factor to scale friction stiffness values; see Remark 3. (Real; Default = 1.0)

GLUE Flag specifying whether MPC for non-pad/disk surfaces with glued contact are used or ignored (Integer, Default = 0). A value of 0 means ignore the MPC; a value of 1 means include the MPCs (see Remark 6).

ICORD Flag indicating whether coordinates are updated or not. A value of 0 means coordinates are not updated. A value of 1 means coordinates are updated using the formula Cnew=Corig+Defl, where Cnew are unpdated coordinates, Corig are original coordinates, and Defl are the final displacements. (Integer; Default = 0)

R1 X direction cosine (basic coord system) of axis of rotation; corresponds to ROTATION A second datablock. (Real; no Default. Required field)

R2 Y direction cosine (basic coord system) of axis of rotation; corresponds to ROTATION A second datablock.

R3 Z direction cosine (basic coord system); corresponds to ROTATION A second datablock. (Real; no Default. Required field)

X X coordinate in basic coord system of a point on the axis of rotation; corresponds to ROTATION A third datablock. (Real; no Default. Required field)

Y Y coordinate in basic coord system of a point on the axis of rotation; corresponds to ROTATION A third datablock. (Real; no Default. Required field)

Z Z coordinate in basic coord system of a point on the axis of rotation; corresponds to ROTATION A third datablock. (Real; no Default. Required field)


16

Remarks:1. This entry is used to calculate complex eigenvalues for brake squeal using unsymmetric stiffness

friction matrice. Options exist to obtain the unsymmetric stiffness matrices using the undeformed geometry (initial contact) or after all specified nonlinear subcases.

2. SOL 600 performs brake squeal calculations. The main (original) MSC.Nastran job with input file jid.dat or jid.bdf spawns the SOL 600 job. MSC.Nastran SOL 600 calculates unsymmetric friction stiffness matrices that1 are saved on a file (jid.marc.bde with associated file jid.marc.ccc). The primary MSC.Nastran job then creates input data for a second MSC.Nastran job (jid.nast.dat) to use the unsymmetric stiffness matrices in an complex eigenvalue extraction. The primary MSC.Nastran job spawns a second MSC.Nastran job to calculate the complex eigenvalues. The complex eigenvalues and eigenvectors are found in jid.nast.f06, jid.nast.op2, etc.

NASCMD is the name of the command used to execute the secondary MSC.Nastran job. NASCMD can be up to 64 characters long and must be left justified in field 2. The sting as entered will be used as is -- except that it will be converted to lower case regardless of whether it is entered in upper or lower case.

RCFILE is the name of an RC file to be used for the secondary MSC.Nastran job. It should be similar to the RC file used for the primary run except that additional memory will usually be necessary to calculate the complex eigenvalues and batch=no should also be specified. RCFILE is limited to 8 characters and an extension of “.rc” will be added automatically. This entry will be converted to upper case in MSC.Nastran but will be converted to lower case before spawning the complex eigenvalue run. This RC file must be located in the same directory as the MSC.Nastran input file. This entry is the same as specifying PARAM,MRRCFILE. One or the other should be used.

3. MPC are produced for contact surfaces with glued contact. DMIGs are produced for contact surfaces without glued contact. The brakes and drums should not use glued contact; other regions of the structure can used glued contact.

4. The continuation lines may be omitted if defaults are appropriate.

5. When a BRKSQL entry is used, PARAM,MRMTXNAM and PARAM,MARCFIL1 should not be entered.

NASCMD Name of a command to run MSC.Nastran (limited to 64 characters) -- used in conjunction with the CONTINUE options on the SOL 600 entry. The full path of the command to execute MSC.Nastran should be entered. The string will be converted to lower case. See Remark 2. (Character; Default = nastran)

RCFILE Name of an RC file to be used with a secondary MSC.Nastran job (limited to 8 characters) -- used in conjunction with the CONTINUE options on the SOL 600 entry. An extension of “.rc” will automatically be added. See Remark 2. (Character; Default = nastb.rc)

Field Contents


6. When brake squeal matrices are output, unsymmetric friction stiffness matrices are output for non-glued contact surfaces. For surfaces with glued contact, MPCs are output. The GLUE flag signals SOL 600 to look for these MPCs and combine them with other MPCs that might be in the model using MPCADD, or if no MPCs were originally used, to add the MCPs due to glued contact. Glued contact surfaces may not be used for the disk-rotor interface. If GLUE is zero or blank, the MPC for glued contact in the brake squeal bde file, if present, will be ignored. Sometimes MSC.Nastran puts out MPCs with only one degree-of-freedom defined. Such MPCs will be ignored; otherwise, MSC.Nastran will generate a fatal error.

7. If ICORD=1, an MSC.Nastran t19 file will be automatic.

Inertia Relief

Defines inertia relief for SOL 600.

Format:

Examples:

SUPORT6 Inertia Relief for SOL 600 - Used in MSC.Nastran Implicit Nonlinear - SOL 600 only

1 2 3 4 5 6 7 8 9 10

SUPORT6 SID METH IREMOV GID CDOF CID IDS1

MODES FMAX FSHIFT

SUPORT6 2 1 3000 123456 0

SUPORT6 3 2

6 0.6 -10.0

SUPORT6 0 3 1 101

SUPORT6 4 3 -2


18

Field Contents

SID Set ID corresponding to a Case Control SUPORT1 command or zero (Integer, Default = 0)0 = if this is the only SUPORT6 entry, use this SUPORT6 entry for all subcases. If there are multiple SUPORT6 entries, use the one with SID=0 for increment zero.N = Use this SUPORT6 entry for the subcase specified by Case Control SUPORT1=NDifferent SUPORT6 entries can be used for each subcase if desired and different subcases can use different methods.If there is only one SUPORT6 entry (with SID=0) no Case Control SUPORT1 commands are necessary.

METH Method to use (Integer, Default = 0)0 = Inertia relief is not active for this subcase 1 = Use the “Kinematic” method – do not enter continuation line. Input will come from fields 5-7 of this entry2 = Use the “Eigenvalue” method – Input data from the 2nd line must is used and fields 5-7 of the primary line must be blank (any SUPORT/SUPORT1 Bulk Data entries are ignored).3 = Use the “Support Method”, usually specified using param,inrel,-1 for other solution sequences (see Remark 3). Do not enter the continuation line. Input will come from all SUPORT entries and those SUPORT1 entries with ID=SID.

IREMOV Method to retain or remove inertia relief from a previous subcase (Integer, Default = 1)1 = Retain inertia relief conditions from previous subcase1 = Remove inertia relief loads immediately2 = Remove inertia relief loads graduallyIREMOV should be blank or 1 unless METH is 0

GID Reference Grid ID for kinematic method (Integer, Default = 0)=0 Use the origin=N Use grid ID N(Used for METH=1 ONLY)

CDOF Degrees of freedom for which inertia relief loads will be applied (Integer, no Default). Enter a string of values identifying the degrees of freedom for the model. For 3D models, usually 123456 is entered. For 2D models two or three degrees of freedom as applicable may be entered. The limit is 6 degrees of freedom for 3D models (see Remark 2).(Used for METH=1 ONLY)

CID Coordinate system flag designating how to apply inertia relief loads (Integer, Default = 0) 0= Basic coordinate systemN=Apply loads in coordinate system designated by field 7 of the GRID entry for grid id N.(Used for METH=1 ONLY)


Remarks:1. The continuation entry is required only if the eigenvalue method (METH=2) is used. Fields 5-7

must be blank if the eigenvalue method is to be used. The continuation option must be omitted if the kinematic method is to be used. The kinematic method is similar to param,inrel,-2 for other solution sequences except that the inertia relief loads are updated at each iteration.

2. For the kinematic method, a maximum of 6 degrees of freedom are allowed for 3D structures (2 or 3 dof for 2D structures). You are responsible for knowing how many rigid body modes need to be “constrained” with inertia relief. For multiple contact bodies which are unsupported at the beginning of an analysis but eventually contact, there are usually 6 dof per flexible body. This situation requires the use of the eigenvalue method with MODES set to 6 times the number of unsupported flexible bodies. If some flexible bodies are supported in some directions but not in others, the number will be less than 6 per body. It is suggested that a preliminary SOL 103 eigenvalue extraction be performed to assess the number of rigid body modes.

3. The parameter INREL is ignored by SOL 600.

User Subroutines

Defines user subroutines for SOL 600

Format:

IDS1 ID of SUPORT1 entries to be used if METH=3 and SID=0 (Integer, no Default) For METH=3, only SUPORT1 entries with ID=IDS1 will be used in increment zero. All SUPORT entries will be used(Used for METH=3 when SID=0 ONLY)

MODES Number of modes to use in the Eigenvalue method (Integer, no Default)(Used for METH=2 ONLY)

FMAX Rigid body modes frequency cutoff (Hz) (Real, Default =1.0 Hz)(Used for METH=2 ONLY)

FSHIFT Shift frequency used in Lanczos eigenvalue extraction (Hz) (Real, Default = -1.0 Hz)(Used for METH=2 ONLY)

USRSUB6 Defines User Subroutines for SOL 600 - Used in MSC.Nastran Implicit Nonlinear - SOL 600 only

Field Contents

1 2 3 4 5 6 7 8 9 10

USRSUB6 U1 U2 U3 U4 U5 U6 U7 U8

U9 U10


20

Examples:

Remarks:1. All user subroutines must reside in the directory where the MSC.Nastran input file resides.

2. All names must be in lower case and have the extension .f

3. SOL 600 combines all user subroutines into one large subroutine named u600.f and u600.f is passed to the command line when spawned from MSC.Nastran.

USRSUB6 UDAMAG UVOID TENSOF

USRSUB6* SEPFORBBC

Field Contents

Ui Name of user subroutine to be included (Character, no Default) See MSC.Marc Volume D for list of available User subroutines


Ch. :

3 Numerical Enhancements

! New Iterative Solver Option, 22

! MDACMS Enhancements, 31

! MPYAD Method 1 Enhancement, 38

! Improved Robustness in the Lanczos Method, 39

! MLDMP in Solution 111 (Pre-Release), 40


22

New Iterative Solver Option

IntroductionStatic structural analyses of very large solid element models pose difficult computational challenges for the solvers available in MSC.Nastran. For most modeling situations, the sparse direct solver is the solver of choice because it is usually the most efficient. However, as the number of degrees of freedom grows ever larger, iterative solution methods become more attractive since they tend to produce results faster than the direct method. For this reason, both solution techniques are available in MSC.Nastran.

In order to increase performance even more in the iterative method, the solver offered by Computational Applications and System Integration, Inc. (CASI) is being introduced into MSC.Nastran.

BenefitsThe introduction of the element-based iterative solver option allows users to run larger jobs faster and with fewer resources (memory and disk) than could be done before. It is anticipated that most jobs will run at least twice as fast when the element-based solver option is specified compared to jobs run with any of the existing MSC.Nastran iterative solver pre-conditioner choices. For very large jobs, the performance could be up to ten times better.

Method and TheoryUntil now, the iterative solution technique in MSC.Nastran has been matrix-based, meaning that the process does not use any element topology information to assist in the solution. The iterative solver operates on the same matrices that are processed by the direct solver. The element-based iterative solver, on the other hand, uses finite element topology and element stiffness matrices directly to obtain the solution. Using this information generally results in smaller pre-conditioners that take less time to factor and that have more model – specific “information” in them so that fewer conjugate gradient iterations are required to arrive at a converged solution compared to matrix-based techniques.

Convergence for the element-based iterative solver is achieved when the value of one of four norms falls below the specified convergence tolerance (the default value is 1.0e-04) and the values of all four norms have fallen below a slightly looser tolerance. To define the norms, let

• b be the original right-hand-side

• A be the global system matrix

• M be the pre-conditioner

• x be the solution at the current step

• r be the current residual

• || || denote 2-norm

• | | denote infinity norm

• ∆x denote the change in current solution x at a particular step.

23CHAPTER 3Numerical Enhancements

Then, the four norms are defined as follows:

1. Reduction in 2-norm of residual

2. Reduction in infinity norm of residual

3. Reduction in preconditioned norm of residual

4. Estimate of normalized energy norm of error in solution

InputsThe SMETHOD Case Control command must be used to select the iterative solver. The SMETHOD command has been enhanced to allow selection of either the existing matrix-based technique or the new element-based technique directly, accepting all default options. This is accomplished by specifying SMETHOD=MATRIX to invoke the existing matrix-based iterative solution technique and SMETHOD=ELEMENT to invoke the new element-based iterative solution technique. The SMETHOD command also accepts the specification of an integer value representing the ID of an ITER Bulk Data entry. In this way, default options can be changed. The PRECOND field of the ITER Bulk Data entry accepts the keyword “CASI” to indicate that the element-based solver is to be used.

OutputsThere is no new MSC.Nastran output produced by the element-based iterative solver. The intermediate convergence parameter output produced by the MSGFLG=YES option of the ITER Bulk Data entry contains the values of the four convergence norms at each iteration. A summary file is produced by the element-based iterative solver that contains various statistics about the solution process. The file name is of the form jid.PCS, where jid is the name of the input data file.

N1rb

--------=

N2rb

------=

N3 rT

M1–r b

TM

1–b⁄=

N4 ∆xT

A∆x( ) xT

Ax( )⁄=


24

Guidelines and LimitationsThe element-based iterative solver is intended for very large static structural analysis models composed mainly of 10 node CTETRA elements. It generally out-performs the direct solver when the problem size exceeds one million degrees of freedom and will out-perform the matrix-based iterative solver when the problem size reaches approximately three million degrees of freedom. The element-based solver is intended for a very specific set of model characteristics. As such, the following limitations apply:

• Available in linear static structural analysis (SOL 101) only

• No GENEL elements allowed

• No K2GG direct input matrix selection allowed

• No ASET/OMIT reduction allowed

• No SUPORTi allowed

• No SCALAR points (explicitly or implicitly defined) allowed

• No heat transfer allowed

• No p-elements allowed

• Only BAR, BEAM, BUSH, ROD, CONROD, ELAS1, ELAS2, SHEAR, QUAD4, QUAD8, QUADR, TRIA3, TRIA6, TRIAR, TETRA, PENTA and HEXA elements are allowed

Demonstration ExampleA simple example is presented that demonstrates the use of the element-based iterative solver. The ITER Case Control command is used to specify the element-based iterative solver. The example problem is used for demonstration purposes only and is not representative of anything in particular. The model data consists of a simple solid brick structure subject to an end load.

Example Input Data

ID CASI,DEMOSOL 101TIME 10000CENDECHO = NONEDISPLACEMENT = ALLsmethod = elementSUBCASE = 1SPC = 1LOAD = 1BEGIN BULKiter,1000,,,,,,,,+it1+it1 precond=casiPARAM,AUTOSPC,YESGRID, 1,, 0.00,0.00,0.00GRID, 2,, 0.00,1.00,0.00GRID, 3,, 0.00,0.00,0.50GRID, 4,, 0.00,1.00,0.50GRID, 5,, 1.25,0.00,0.00


GRID, 6,, 1.25,1.00,0.00GRID, 7,, 1.25,0.00,0.50GRID, 8,, 1.25,1.00,0.50GRID, 9,, 2.50,0.00,0.00GRID, 10,, 2.50,1.00,0.00GRID, 11,, 2.50,0.00,0.50GRID, 12,, 2.50,1.00,0.50GRID, 13,, 3.75,0.00,0.00GRID, 14,, 3.75,1.00,0.00GRID, 15,, 3.75,0.00,0.50GRID, 16,, 3.75,1.00,0.50GRID, 17,, 5.00,0.00,0.00GRID, 18,, 5.00,1.00,0.00GRID, 19,, 5.00,0.00,0.50GRID, 20,, 5.00,1.00,0.50GRID, 21,, 6.25,0.00,0.00GRID, 22,, 6.25,1.00,0.00GRID, 23,, 6.25,0.00,0.50GRID, 24,, 6.25,1.00,0.50GRID, 25,, 7.50,0.00,0.00GRID, 26,, 7.50,1.00,0.00GRID, 27,, 7.50,0.00,0.50GRID, 28,, 7.50,1.00,0.50GRID, 29,, 8.75,0.00,0.00GRID, 30,, 8.75,1.00,0.00GRID, 31,, 8.75,0.00,0.50GRID, 32,, 8.75,1.00,0.50GRID, 33,,10.00,0.00,0.00GRID, 34,,10.00,1.00,0.00GRID, 35,,10.00,0.00,0.50GRID, 36,,10.00,1.00,0.50GRID, 37,, 0.00,0.50,0.00GRID, 38,, 0.00,0.50,0.50GRID, 39,, 1.25,0.50,0.00GRID, 40,, 1.25,0.50,0.50GRID, 41,, 2.50,0.50,0.00GRID, 42,, 2.50,0.50,0.50GRID, 43,, 3.75,0.50,0.00GRID, 44,, 3.75,0.50,0.50GRID, 45,, 5.00,0.50,0.00GRID, 46,, 5.00,0.50,0.50GRID, 47,, 6.25,0.50,0.00GRID, 48,, 6.25,0.50,0.50GRID, 49,, 7.50,0.50,0.00GRID, 50,, 7.50,0.50,0.50GRID, 51,, 8.75,0.50,0.00GRID, 52,, 8.75,0.50,0.50GRID, 53,,10.00,0.50,0.00GRID, 54,,10.00,0.50,0.50GRID, 55,, 0.00,0.00,0.25GRID, 56,, 0.00,1.00,0.25GRID, 57,, 1.25,0.00,0.25GRID, 58,, 1.25,1.00,0.25GRID, 59,, 2.50,0.00,0.25GRID, 60,, 2.50,1.00,0.25GRID, 61,, 3.75,0.00,0.25GRID, 62,, 3.75,1.00,0.25GRID, 63,, 5.00,0.00,0.25GRID, 64,, 5.00,1.00,0.25GRID, 65,, 6.25,0.00,0.25


26

GRID, 66,, 6.25,1.00,0.25GRID, 67,, 7.50,0.00,0.25GRID, 68,, 7.50,1.00,0.25GRID, 69,, 8.75,0.00,0.25GRID, 70,, 8.75,1.00,0.25GRID, 71,,10.00,0.00,0.25GRID, 72,,10.00,1.00,0.25GRID, 73,, 0.625,0.00,0.00GRID, 74,, 0.625,1.00,0.00GRID, 75,, 0.625,0.00,0.50GRID, 76,, 0.625,1.00,0.50GRID, 77,, 1.875,0.00,0.00GRID, 78,, 1.875,1.00,0.00GRID, 79,, 1.875,0.00,0.50GRID, 80,, 1.875,1.00,0.50GRID, 81,, 3.125,0.00,0.00GRID, 82,, 3.125,1.00,0.00GRID, 83,, 3.125,0.00,0.50GRID, 84,, 3.125,1.00,0.50GRID, 85,, 4.375,0.00,0.00GRID, 86,, 4.375,1.00,0.00GRID, 87,, 4.375,0.00,0.50GRID, 88,, 4.375,1.00,0.50GRID, 89,, 5.625,0.00,0.00GRID, 90,, 5.625,1.00,0.00GRID, 91,, 5.625,0.00,0.50GRID, 92,, 5.625,1.00,0.50GRID, 93,, 6.875,0.00,0.00GRID, 94,, 6.875,1.00,0.00GRID, 95,, 6.875,0.00,0.50GRID, 96,, 6.875,1.00,0.50GRID, 97,, 8.125,0.00,0.00GRID, 98,, 8.125,1.00,0.00GRID, 99,, 8.125,0.00,0.50GRID,100,, 8.125,1.00,0.50GRID,101,, 9.375,0.00,0.00GRID,102,, 9.375,1.00,0.00GRID,103,, 9.375,0.00,0.50GRID,104,, 9.375,1.00,0.50GRID,105,, 0.625,0.00,0.25GRID,106,, 0.625,1.00,0.25GRID,107,, 1.875,0.00,0.25GRID,108,, 1.875,1.00,0.25GRID,109,, 3.125,0.00,0.25GRID,110,, 3.125,1.00,0.25GRID,111,, 4.375,0.00,0.25GRID,112,, 4.375,1.00,0.25GRID,113,, 5.625,0.00,0.25GRID,114,, 5.625,1.00,0.25GRID,115,, 6.875,0.00,0.25GRID,116,, 6.875,1.00,0.25GRID,117,, 8.125,0.00,0.25GRID,118,, 8.125,1.00,0.25GRID,119,, 9.375,0.00,0.25GRID,120,, 9.375,1.00,0.25GRID,121,, 0.625,0.50,0.00GRID,122,, 0.625,0.50,0.50GRID,123,, 1.875,0.50,0.00GRID,124,, 1.875,0.50,0.50GRID,125,, 3.125,0.50,0.00


GRID,126,, 3.125,0.50,0.50GRID,127,, 4.375,0.50,0.00GRID,128,, 4.375,0.50,0.50GRID,129,, 5.625,0.50,0.00GRID,130,, 5.625,0.50,0.50GRID,131,, 6.875,0.50,0.00GRID,132,, 6.875,0.50,0.50GRID,133,, 8.125,0.50,0.00GRID,134,, 8.125,0.50,0.50GRID,135,, 9.375,0.50,0.00GRID,136,, 9.375,0.50,0.50GRID,137,, 0.000,0.50,0.25GRID,138,, 1.250,0.50,0.25GRID,139,, 2.500,0.50,0.25GRID,140,, 3.750,0.50,0.25GRID,141,, 5.000,0.50,0.25GRID,142,, 6.250,0.50,0.25GRID,143,, 7.500,0.50,0.25GRID,144,, 8.750,0.50,0.25GRID,145,,10.000,0.50,0.25GRID,146,, 0.625,0.50,0.25GRID,147,, 1.875,0.50,0.25GRID,148,, 3.125,0.50,0.25GRID,149,, 4.375,0.50,0.25GRID,150,, 5.625,0.50,0.25GRID,151,, 6.875,0.50,0.25GRID,152,, 8.125,0.50,0.25GRID,153,, 9.375,0.50,0.25CTETRA 1 1 1 4 3 7 137 38 55 105 122 75CTETRA 2 1 1 4 7 5 137 122 105 73 146 57CTETRA 3 1 4 7 5 8 122 57 146 76 40 138CTETRA 4 1 1 2 4 5 37 56 137 73 121 146CTETRA 5 1 2 4 5 8 56 146 121 106 76 138CTETRA 6 1 2 8 5 6 106 138 121 74 58 39CTETRA 7 1 5 8 7 11 138 40 57 107 124 79CTETRA 8 1 5 8 11 9 138 124 107 77 147 59CTETRA 9 1 8 11 9 12 124 59 147 80 42 139CTETRA 10 1 5 6 8 9 39 58 138 77 123 147CTETRA 11 1 6 8 9 12 58 147 123 108 80 139CTETRA 12 1 6 12 9 10 108 139 123 78 60 41CTETRA 13 1 9 12 11 15 139 42 59 109 126 83CTETRA 14 1 9 12 15 13 139 126 109 81 148 61CTETRA 15 1 12 15 13 16 126 61 148 84 44 140CTETRA 16 1 9 10 12 13 41 60 139 81 125 148


28

CTETRA 17 1 10 12 13 16 60 148 125 110 84 140CTETRA 18 1 10 16 13 14 110 140 125 82 62 43CTETRA 19 1 13 16 15 19 140 44 61 111 128 87CTETRA 20 1 13 16 19 17 140 128 111 85 149 63CTETRA 21 1 16 19 17 20 128 63 149 88 46 141CTETRA 22 1 13 14 16 17 43 62 140 85 127 149CTETRA 23 1 14 16 17 20 62 149 127 112 88 141CTETRA 24 1 14 20 17 18 112 141 127 86 64 45CTETRA 25 1 17 20 19 23 141 46 63 113 130 91CTETRA 26 1 17 20 23 21 141 130 113 89 150 65CTETRA 27 1 20 23 21 24 130 65 150 92 48 142CTETRA 28 1 17 18 20 21 45 64 141 89 129 150CTETRA 29 1 18 20 21 24 64 150 129 114 92 142CTETRA 30 1 18 24 21 22 114 142 129 90 66 47CTETRA 31 1 21 24 23 27 142 48 65 115 132 95CTETRA 32 1 21 24 27 25 142 132 115 93 151 67CTETRA 33 1 24 27 25 28 132 67 151 96 50 143CTETRA 34 1 21 22 24 25 47 66 142 93 131 151CTETRA 35 1 22 24 25 28 66 151 131 116 96 143CTETRA 36 1 22 28 25 26 116 143 131 94 68 49CTETRA 37 1 25 28 27 31 143 50 67 117 134 99CTETRA 38 1 25 28 31 29 143 134 117 97 152 69CTETRA 39 1 28 31 29 32 134 69 152 100 52 144CTETRA 40 1 25 26 28 29 49 68 143 97 133 152CTETRA 41 1 26 28 29 32 68 152 133 118 100 144CTETRA 42 1 26 32 29 30 118 144 133 98 70 51CTETRA 43 1 29 32 31 35 144 52 69 119 136 103CTETRA 44 1 29 32 35 33 144 136 119 101 153 71CTETRA 45 1 32 35 33 36 136 71 153 104 54 145CTETRA 46 1 29 30 32 33 51 70 144 101 135 153


CTETRA 47 1 30 32 33 36 70 153 135 120 104 145CTETRA 48 1 30 36 33 34 120 145 135 102 72 53PSOLID 1 1 0MAT1,1,1.0SPC1,1,456,1,THRU,153SPC 1 1 123 0.SPC 1 2 123 0.SPC 1 3 123 0.SPC 1 4 123 0.SPC 1 55 123 0.SPC 1 56 123 0.SPC 1 37 123 0.SPC 1 38 123 0.SPC 1 137 123 0.PLOAD4* 1 48 1.000000000E+00 1.000000000E+00** 1.000000000E+00 1.000000000E+00 33 30** 0 1.000000000E+00 0.000000000E+00 0.000000000E+00** PLOAD4* 1 45 1.000000000E+00 1.000000000E+00** 1.000000000E+00 1.000000000E+00 33 32** 0 1.000000000E+00 0.000000000E+00 0.000000000E+00** ENDDATA

Example OutputThe output generated consists of the usual MSC.Nastran output as well as an output file generated by the element-based iterative solver. The contents of this file summarize various statistics about the solution process. Some of the statistics include number of terms in the various matrices, number of degrees of freedom, number of iterations taken and convergence parameter values. The file will have a suffix of .PCS and appear in the same location as other output files produced by the job. The contents of the .PCS file for the example problem are shown here for reference.

******************************************************************************(C) Copyright 1992-2004Computational Applications and System Integration Inc.All rights Reserved.******************************************************************************

Job:./v2006rgat:Wed Oct 12 10:30:35 2005

******************************************************************************

ESTIMATED MEMORY (MB): 0.094738Preallocated Virtual Memory : 27.3828 MBVirtual Memory Used : 1.96344 MB

************************************************************************************************************************************************************


30

(C) Copyright 1992-2004Computational Applications and System Integration Inc.All rights Reserved.******************************************************************************

Job:./v2006rgat:Wed Oct 12 10:30:36 2005

Degrees of Freedom: 459DOF Constraints: 27Elements: 48Assembled: 0Implicit: 48Nodes: 153Number of Load Cases: 1

Nonzeros in Upper Triangular part of Global Stiffness Matrix : 0Nonzeros in Preconditioner: 8298*** Precond Reorder: MLD ***Nonzeros in V: 2160Nonzeros in factor: 5220*** Primal Preconditioner Activated ***VTAeV:uTime:0 Sec:sTime:0 Sec

Total Operation Count: 851878Total Iterations In PCG: 8Average Iterations Per Load Case: 8.000000Input PCG Error Tolerance: 1e-04Achieved PCG Error Tolerance: 5.81869e-05

DETAILS OF SOLVER CP TIME(secs)User SystemAssembly0 0Preconditioner Construction0 0Preconditioner Factoring0 0Preconditioned CG0 0******************************************************************************Total PCG Solver CP Time: User: 0 secs: System: 0 secs******************************************************************************Available Physical Memory (RAM) : 0 MBEstimate of Memory Usage In CG : 0.080898 MBEstimate of Disk Usage : 0.09228 MBPreallocated Virtual Memory : 27.3828 MBVirtual Memory Used : 4.16164 MB*** Implicit Matrix Multiplication Activated : Mode 3 *********************************************************************************Multiply with A time in decisecs 0Precond solve time in decisecs 0******************************************************************************Total Elapsed Time (Secs): 1******************************************************************************


MDACMS Enhancements

BackgroundIn the prior release of MSC.Nastran 2005 r2, Matrix Domain Automated Component Modal Synthesis (MDACMS) became the default ACMS method. The older Geometric Domain approach (GDACMS) remains available but is not the recommended ACMS method. The PARTOPT keyword on the DOMAINSOLVER Executive System command is used to choose between the Geometric and Matrix (or DOF) domains: PARTOPT=DOF is now the default for ACMS.

SummaryThe primary goal of development of MSC.Nastran 2005 r3 of MDACMS is to improve performance by reducing disk I/O and Executive System overhead. Generally, this is achieved by allowing Nastran to utilize memory more effectively than in the past. In addition, several subDMAPs have been consolidated into a single new DMAP module.

Specific enhancements to the MDACMS capability include the following:

• The ability to specify key scratch datablocks for Scratch Memory (SMEM) residence via a new FMS command: MEMLIST.

• Introduction of a new module to perform functions in support of residual vector calculations: the RESMOD module.

• Enhancements to matrix multiply-and-add (MPYAD module) Method 1.

New FMS Command: MEMLISTThe File Management Section (FMS) has been enhanced to include a new MEMLIST command, described below. The purpose of the MEMLIST command is to limit the use of Scratch Memory (SMEM) to a subset of Nastran scratch datablocks. In this way, the effectiveness of SMEM increases to the extent that the user knows which scratch datablocks are likely to be accessed most often.

A pre-defined MEMLIST command has been created and is available in the form of an INCLUDE file. This file is delivered in the SSSALTERDIR directory, which is available when a full Nastran installation has been performed. In order to access this file, specify the following INCLUDE command in the FMS Section of the input file:

INCLUDE ‘SSSALTERDIR:memlist.acms’

This file lists scratch datablocks that will reduce the disk I/O by a significant amount, provided that enough Scratch Memory has been specified.

The following is the MSC.Nastran Quick Reference Guide description of the MEMLIST command.


32

Specify a list of scratch datablocks that may reside in scratch memory (SMEM).

Format:MEMLIST DATABLK = (DBname1, DBname2, ..., DBnamei)

Remarks:1. Only NDDL and local scratch datablocks may be included in MEMLIST specification.

2. Datablocks specified will reside in SMEM on a first come, first served basis.

3. Datablocks not specified by this command will not reside in SMEM.

4. Database directories for the SCRATCH DBset reside in SMEM and are not affected by any MEMLIST specification.

5. Continuation lines are allowed.

6. Multiple MEMLIST commands are honored.

7. Scratch I/O activity is reported in the F04 file by including DIAG 42 in the Executive Section.

Example:MEMLIST DATABLK = (KOO, MOO, KQQ, MQQ)

If generated, datablocks KOO, MOO, KQQ, and MQQ will reside in scratch memory. All other datablocks will be excluded from scratch memory.

New Module: RESMODThe ACMS process entails computing residual vectors at each automatically generated component. Each step taken during residual vector calculations is carried out by a particular subDMAP call. In order to streamline the DMAP and reduce Executive System overhead, the RESMOD module has been developed for MSC.Nastran 2005 r3. The RESMOD module is only invoked during MDACMS operations, when the size of the vectors is relatively small, which is a characteristic of MDACMS computations.

The module syntax is similar to the MATMOD module, since the first parameter (P1) defines the operation to be performed. However, unlike MATMOD, P1 is a character pneumonic instead of an integer code value. The complete DMAP description is below.

MEMLIST Specify Datablocks Eligible for SMEM

Describer Meaning

DBnamei Name of a MSC.Nastran datablock.


Perform linear algebra functions to support residual vector calculations.

Format:

Input Data Blocks:

Output Data Blocks:

Parameters:

Remark:

Each option corresponds to a different value of the first parameter, P1, as follows.

Details for each option are given in the following sections.

RESMOD RESVEC Calculations

RESMOD I1,I2,I3,I4,I5/O1,O2,O2,O3,O4,O5/P1/P2/P3/P4/P5/P6 $

Ii: Input data blocks. I1 is required. I2 through I5 may not be necessary depending on the value of P1.

Oi Output data blocks.

P1 Input-character-no default. Option selection described in the table below.

P2,P3,P4 Input-integer-default=0. Integer parametric data depending on P1.

P5,P6 Input-real-default=0.0. Real parametric data depending on P1.

P1 Value Brief Description

‘ATBC’ Performs [A]T[B][C] if [C] present; [A]T[B][A] otherwise

‘MPART’ Partitions stiffness, mass, and eigenvector matrices based on mass content

‘LININD’ Find linearly independent and dependent vectors of a matrix

‘LDSWEEP’ Sweeps “modal” loads for load vectors

‘USWEEP’ Sweeps a matrix for small vectors


34

Option P1 = ‘ATBC’

Performs the matrix multiplication [I1]T[I2][I3] if [I3] is present; [I1]T[I2][I1] otherwise.

Format:

Input Data Blocks:

Output Data Blocks:

Remark:

[I2] is assumed to be symmetric.

Example:

Compute the product [D] = [A] T [B] [C]

Option P1 = ‘MPART’Partitions stiffness, mass, and eigenvector matrices based on mass content.

Format:

Input Data Blocks:

RESMOD I1,I2,I3,,/O1,,,,/’ATBC’ $

I1,I2,I3 Any matrix data blocks.

O1 Matrix product.

RESMOD A,B,C,,/D,,,,/’ATBC’ $

RESMOD PHI,K,M,,/PHI0,K0,PHI1,M1,K1/’MPART’////ZROSTIFF/ZROMASS $

PHI A set of eigenvectors.

K Stiffness matrix associated with [PHI].

M Mass matrix associated with [PHI].


Output Data Blocks:

Parameters:

Remark:

Only real matrices are supported.

Option P1 = ‘LININD’Partitions a matrix into linearly independent and dependent sets.

Format:

Input Data Blocks:

Output Data Blocks:

Parameters:

PHI0 Massless eigenvectors.

K0 Stiffness associated with [PHI0].

PHI1 Eigenvectors which contain mass.

M1 Mass associated with [PHI1].

K1 Stiffness associated with [PHI1].

ZROSTIFF Input-real-default=1.0E-8. Null stiffness filter criteria.

ZROMASS Input-real-default=1.0E-16. Null mass filter criteria.

RESMOD U,M,,,/U0,U1,,,/’LININD’////ZROVEC $

U Any real matrix.

M Mass matrix associated with [U].

U0 Linearly dependent vector set from [U].

U1 Linearly independent vector set from [U].

ZROVEC Input-real-default=1.0E-6. Null filter criteria.


36

Remarks:1. M may be purged, in which case the identity matrix is assumed.

2. Output matrices [U0] and [U1] should satisfy the following conditions:

3. Only real matrices are supported.

Option P1 = ‘LDSWEEP’Sweeps “modal” loads for load vectors.

Format:

Input Data Blocks:

Output Data Blocks:

Parameters:

Remarks:1. The filtered load vectors are:


RESMOD LD,PHI,MXX,MQQ,/LDIND,,,,/’LDSWEEP’/NORMFLG $

LD A set of load vectors.

PHI Modal vectors.

MXX Mass matrix, physical degrees of freedom.

MQQ Mass matrix, modal degrees of freedom.

LDIND Filtered load vectors.

NORMFLG Input-integer-default=0. Normalization flag. Set to –1 to unit normalize load vectors.

U0[ ] TM[ ] U0[ ] computational zeros=

U1[ ] TM[ ] U0[ ] 0.0>

LDIND[ ] LD[ ]= M[ ] PHI[ ]– INV PHI[ ] TM[ ] PHI[ ]( ) PHI[ ] T

LD[ ]⋅ ⋅


Option P1 = ‘USWEEP’Sweeps a matrix for small vectors.

Format:

Input Data Blocks:

Output Data Blocks:

Parameters:

Remarks:1. The filtered vectors are:


RESMOD U,PHI,MXX,MQQ,/UIND,,,,/’USWEEP’/NORMFLG $

U A set of vectors.

PHI Modal vectors.

MXX Mass matrix, physical degrees of freedom.

MQQ Mass matrix, modal degrees of freedom.

UIND Filtered vectors.

NORMFLG Input-integer-default=0. Normalization flag. Set to –1 to unit normalize input vectors.

UIND[ ] U[ ]= INV PHI[ ] MQQ[ ] PHI[ ] T( )– MXX[ ] U[ ]⋅ ⋅


38

MPYAD Method 1 EnhancementThe Storage 3 option of matrix multiply and add (MPYAD) module Method 1 has been enhanced remove null rows of the [B] matrix, where [B] is the second matrix in the matrix product

This results in a reduction of the number of operations necessary to complete the matrix multiply. MPYAD Method 1 Storage 3 is frequently invoked during MDACMS reduction operations.

ExampleThis example demonstrates the potential impact of these enhancements.

Problem Definition:• Acoustic Analysis (modal frequency response, SOL 111)

• Over 600,000 grid points; 3.5 million degrees of freedom

• Over 4,000 structure modes up to 600 Hertz; 200 fluid modes

• 12 load cases; over 700 forcing frequencies

Machine Resources• Linux IA64 with 12Gb main memory

• HP DS2100 3-way striped scratch disk

The MSC.Nastran 2005 r2 run was made with one gigabyte of memory (“mem=1gb”). The MSC.Nastran 2005 r3 run was made using “mem=8gb smem=7gb”. This resulted in the same Open Core size (1gb) but with 7gb memory devoted to SMEM. The standard MEMLIST specification found in SSSALTER:memlist.acms was used for MSC.Nastran 2005 r3. Finally, both runs utilized serial processing.

Version Elap (sec) CPU (sec) Total I/O (gb) HiWater Disk (gb)

MSC.Nastran 2005 r2 12472 10734.3 37.303 1501.81

MSC.Nastran 2005 r3 9369 8239.3 31.873 684.402

Speedup 24.88% 23.24% 14.56% 54.43%

D[ ] A[ ] B[ ] C[ ]±±=


Improved Robustness in the Lanczos MethodA new feature in the READ module is used to scale some intermediate quantities computed during the Lanczos procedure. The effect is a more stable factorization, with a lower MAT RATIO, particularly when Lagrange multipliers are used. In practical examples, this feature has reduced max ratios by six orders of magnitude.

This feature may be disabled by setting system cell 166 to 48.


40

MLDMP in Solution 111 (Pre-Release)The Multi-Level Distributed Memory Parallel (MLDMP) option is available for solution 111 in pre-release status. This option generates eigenvectors using the Lanczos method in a hierarchic parallel fashion. That is, the frequency range is divided into a user-specified number of segments, and each segment is assigned to a logical group or cluster of processors. The modes in each segment are computed in parallel, and in turn, each cluster uses a matrix-based domain decomposition to compute the modes for its segment in parallel. The new option provides improved scaling across a larger number of processors.

User interfaceThe MLDMP option may be selected by specifying

DOMAINSOLVER MODES (PARTOPT=DOF)

in the Executive Control Section of the input file, and then using the DMP and NCLUST command line keywords to specify the number of processors and the number of logical clusters, respectively. Recall that the number of logical clusters is the same as the number of frequency segments. The value of DMP should be a multiple of NCLUST. The number of matrix domains will be the quotient DMP/NCLUST, so it is recommended that values of DMP and NCLUST be chosen so that DMP/NCLUST is a power of 2.

The upper frequency limit must be specified on the EIGRL bulk data entry, and it is recommended that a lower frequency limit be specified as well.

Case StudyA 1.3 Mdof body-in-white model was run, computing modes up to 300 Hz (1397 eigenvalues), using a cluster of 8 IBM P655 servers, each with 8 1.5-GHz POWER4+ processors and 16 GB of physical memory. Each node had two local, 73GB disks for scratch.

The parallel performance scaled well, achieving nearly a 6-fold improvement when using 16 processors.

The MLDMP option also reduces the per-processor resource requirements in terms of both memory required and I/O performed:

0123456

Speedup

2 4 8 16

Number of Processors

DMP Performance (Elapsed Time)


0

500

1000

1500

2000

I/O p

er

pro

cess

or

(GB

)

1 2 4 8 16


I/O Reduction

050

100150200250

Meg

awo

rds

1 2 4 8 16


Memory Hiwater


42


Ch. :

4 Elements

! Three-Node Beam Element, 44

! CWSEAM Connector Elements, 54

! Line Interface Element, 65

! Arbitrary Beam Cross-Section, 74


44

Three-Node Beam Element

IntroductionA general three-node beam element has been developed for linear static, modal, dynamic and buckling analyses. The element has been implemented as a curved one-dimensional Timoshenko beam element so that both the initial curvatures of beam reference axis and the cross-section shears are included in the formulation of linear strain-displacement relations. The geometry of beam axis is specified by the offset vectors from the grid points to the shear centers of the beam cross-sections. The quadratic interpolation is used for both beam axis and the shape functions. When a three-node beam element degenerates to a two-node straight beam element, the linear interpolation is adopted. Variable cross-sectional properties are interpolated quadratically for a three-node and linearly for a degenerate two-node beam element.

Unlike MSC.Nastran two-node straight beam element (CBEAM), the three-node beam element is developed based on the displacement method, in which the displacements at nodal points are taken as primary variables and the variational principle is applied to minimize the total element energy in formulating element stiffness, consistent mass and differential stiffness matrices.

At each beam element nodal point, there are three translative and three rotational degrees of freedom, respectively. When the beam cross-section torsional warping effect is considered, another degree of freedom, which represents the warping variable, is added to the six nodal degrees of freedom at each grid point. The warping degrees of freedom are represented by either scalar or grid points.

Element-related loads, such as distributed forces and moments, as well as thermal loads, can be applied on this element. The solution output includes element stresses, strains, forces and moments, element strain energy and grid point forces.

BenefitsPerhaps the most suitable situation of the application of three-node beam element is that the element is used in conjunction with higher-order shell elements, such as TRIA6 and QUAD8, to model, for instance, stiffeners. It can also be applied as an alternative to the existing straight two-node beam element in modeling favorably a structural geometry with initial curvatures.

In addition to normal stresses and strains at beam cross-sections, both shear stresses and strains are also recovered at cross-sectional stress output points. When warping effect is considered, normal stresses caused by cross-sectional bi-moments are computed and output accordingly.

InputSeveral new Bulk Data entries have been created for three-node beam element connection, property, distributed thermal and mechanical loads. They are CBEAM3, PBEAM3, TEMPB3 and PLOADB3. For a detailed description of each entry, please refer to MSC.Nastran Quick Reference Guide in accompany with this release.

45CHAPTER 4Elements

Guidelines and Limitations

Geometry and Coordinate Systems

The geometry of a three-node beam element is specified by element connection Bulk Data entry

CBEAM3. The offset vectors , , and , are measured from grid points GA, GB and GC to the corresponding shear centers, A, B and C, respectively, at the beam cross-sections, as shown in Figure 4-1. Shear centers, A, B and C, are coplanar points. They define a plane in space if they are non-collinear. A quadratic approximation of the locus of beam shear center is uniquely defined by the spatial locations of these three shear centers. In what follows, we will refer the locus of beam shear center as the beam reference axis, or simply, beam axis. Taking the locus of shear center as the beam primary reference axis is consistent with the CBEAM element. Theoretically, the beam reference axis can be chosen arbitrarily. We also assume that the beam reference axis is a smooth spatial curve. The beam cross-section is perpendicular to the beam axis.

Figure 4-1 Locus of Shear Center of Three-node Beam Element

The element coordinate system ( , , ) is established by the orientation vector in the same way as what is defined for CBEAM element, as shown in Figure 4-1.

For a spatial curve, such as the beam reference axis, the natural coordinate system is its Frenet-Serret

frame , as shown in Figure 4-1. Here , and are the unit tangential, normal and bi-normal

vectors, respectively. Tangent vector points to the direction from A to B along the beam axis. Vector

is in the plane defined by these three non-collinear shear centers and points inwardly with respect to

Wa Wb Wc

GA GC

GB

aw

cw

bw

A

C

B

Locus of Shear Center

te

ne

be

elemX

elemYelemZ

ν

Wc

GB

GCGA

Wa

Wb

B

et

eb

en

C

Locus of Shear Center

ν

YelemZelem

Xelem

A

Xelem Yelem Zelem ν

et en eb, ,( ) et en eb

et

en


46

the bending of beam axis. Bi-normal vector is perpendicular to both and by following the right-

hand rule of . When the beam axis is a straight line, i.e., three sectional shear centers are collinear, the Frenet-Serret frame is undefined. Then it will be replaced by the element coordinate system.

To formulate finite element equations and define the beam element properties, a local convected

coordinate system is created. The x-axis is always along the beam axis and its convected x

coordinate is measured by the arc-length, s. Its base vector, , is taken as same as vector . The base

vectors of the local coordinate system, and , are defined in such a way that they rotate an angle

(pre-twist angle), from and , respectively, in the plane of beam cross-section, as shown in

Figure 4-2. The orthogonal curvilinear coordinate system is introduced here as the local

convected coordinate system, instead of the Frenet-Serret frame, to model the pre-twist of the beam cross-section. When , the Frenet-Serret frame (or the element coordinate system if the beam axis

is straight) becomes the local convected coordinate system. The angle, , may vary along the beam axis. The pre-twist angles at three beam cross-sections are given in Bulk Data entry, CBEAM3.

Figure 4-2 Local Coordinate System on a Beam Cross-Section

The properties of a three-node beam element listed in Bulk Data entry, PBEAM3, are referred to the local coordinate system. The output of element stresses, strains and forces is also presented in the local coordinate system.

et en

eb et= en⋅

ex ey ez, ,( )

ex et

ey ez φ

en eb

ex ey ez, ,( )

φ 0=

φ

φ

ne

be

yeze

Shear Center

en

ey

eb

ez

ShearCenter

47CHAPTER 4Elements

Element Properties, Materials and Loads

There are some similarities between PBEAM and PBEAM3 entries in terms of both format and content. Attention, however, should be paid to their differences. The local coordinate system is primarily referred in defining cross-sectional properties, such as area moments and product of inertia, and locations of neutral axis and nonstructural mass center of gravity. Four stress output points on a beam cross-section is also specified in the local coordinate system. Unlike PBEAM, in which the user can specify the properties at as many as nine intermediate stations, PBEAM3 requires their definitions at only three grid locations. For a degenerate two-node beam element, those fields related to the mid-grid are ignored. Values of warping function and its gradients at stress output points are required if torsional warping stresses are to be recovered.

Shear effectiveness factors may not be zero. Since the element is formulated on the Timoshenko beam theory and quadratic shape functions are used for interpolation, zero shear effectiveness factors will not automatically lead to a three-node Euler-Bernoulli beam element.

Both MAT1 and MAT2 entries can be referred by PBEAM3.

The loads related to the three-node beam element are element thermal and distributed mechanical loads, given by TEMPB3 and PLOADB3, respectively. The distributed forces and moments can be specified in one of local, element, basic and any user-specified coordinate systems. The load must be applied over entire length of the element along the beam axis.

Limitations

There are some limitations at current implementation with the three-node beam element. First of all, it is limited to linear analysis solution sequences only. Heat transfer analysis with the three-node beam element is not supported. Other limitations are identified as follows.

• X-Y PLOT output;

• Random analysis;

• PBEAML and PBCOMP related features;

• CBEAM related features, such as pin-flags and shear relief;

Formulation

Strain-Displacement Relations

The formulation of a three-node beam element is based on Timoshenko beam theory. The kinematical assumption hereafter is that the displacement vector at an arbitrary point of the beam cross-section is uniquely defined by the displacement vector at the beam reference axis and the rotations of the cross-section, superposed by a longitudinal warping displacement. For small deformation theory, the rotation of the cross-section is a vector. The displacement vector at point (s, y, z) of a beam cross-section is

u s y z, ,( ) Uxex= Uyey Uzez+ +


48

where:

in which , and are three translative displacement components at the beam axis; ,

and are three rotational degrees of freedom of the beam cross-section; and is a given

warping function and the warping degree of freedom. The assumption of the warping displacement is based on the Saint-Venant torsion theory of straight bars.

The Green-Lagrangian normal and shear strains, , are

where:

in which , the derivative with regard to the arc-length of beam axis.

Constitutive Relation

The general stress-strain relations are given, including thermal loads, at an arbitrary point of a beam cross-section, as

Ux s y z, ,( ) u s( )= zθy s( ) yθz s( )– ω s( )ψ y z,( )+ +

Uy s y z, ,( ) ν s( )= zθx s( )–

Uz s y z, ,( ) w s( )= yθx s( )+

u s( ) v s( ) w s( ) θx s( )

θy s( ) θz s( ) ψ y z,( )

ω s( )

ε γy γz, ,

ε ε0= zχy yχz– ψωs+ +

γy γy0= zχx– ψyω+

γz γz0= yχx ψzω+ +

ε0 u s,= κyw κ zv–+

γy0 ν s,= θz– κ zu κxw–+

γz0 w s,= θy κ yu– κxν+ +

χx θx s,= κ zθy– κyθz+

χy θy s,= κ zθx+

χz θz s,= κyθx–

ψy∂ψ∂y-------= κ zψ+

ψz∂ψ∂z-------= κyψ–

( ) s, ∂ ( ) ∂s( )⁄=

49CHAPTER 4Elements

where are material elastic constants, α the thermal expansion coefficient and the variation of

temperature.

Element Forces and Moments

The axial and shear forces as well as torsion and bending moments of the cross-section in the local coordinate system are

and the bi-shear force and bi-moment, which are associated with the warping degree of freedom and its derivative, are

OutputElement forces, moments, stresses and strains, are computed at three beam cross-sections, in the local coordinate system. These three cross-section locations are related to either three grid points or two Gauss integration points and the parametrized origin. Both normal and shear stresses and strains are output at four cross-sectional stress recovery points in the local coordinate system.

σ

στy

τz C11 C12 C13

C22 C23

Sym C33

εγy

γz α∆ T

0

0

–

= =

Cij ∆T

Nx σdAA∫=

Vy τy AdA∫=

Vz τ z AdA∫=

Mx yτz zτy–( ) AdA∫=

My σz AdA∫=

Mz yσ–( ) Ad∫=

Vb τyψy τ zψz+( ) AdA∫=

Mb σψ AdA∫=


50

The output examples of element forces, stresses and strains are shown in Listing 4-1, Listing 4-2, and Listing 4-3.

Listing 4-1 Output of Element Forces and Moments

Listing 4-2 Output of Element Stresses

Listing 4-3 Output of Element Strains

F O R C E S I N B E A M 3 E L E M E N T S ( C B E A M 3 ) - FORCES IN LOCAL COORDINATE SYSTEM - GRID/ - BENDING MOMENTS - - SHEAR FORCES - AXIAL TOTAL BI-SHEAR BI-MOMENT ELEMENT-ID GAUSS MY MZ QY QZ FORCE TORQUE FORCE0 2901 2901 0.0 -1.156075E+03 -2.348231E+01 0.0 1.087807E+02 0.0 0.0 0.0 2902 0.0 -1.125649E+02 -1.096482E+02 0.0 1.902465E+01 0.0 0.0 0.0 2903 0.0 -6.343201E+02 -6.656523E+01 0.0 6.390266E+01 0.0 0.0 0.00 3901 3901 0.0 -1.048109E+03 -3.558532E+00 0.0 1.042715E+02 0.0 0.0 0.0 3903 0.0 -7.528904E+02 -7.162810E+01 0.0 7.585925E+01 0.0 0.0 0.0 3904 0.0 -9.004999E+02 -3.759332E+01 0.0 9.006535E+01 0.0 0.0 0.00 3902 3903 0.0 -7.267761E+02 -7.611831E+01 0.0 7.135274E+01 0.0 0.0 0.0 3902 0.0 -1.843143E+01 -1.042837E+02 0.0 3.180659E+00 0.0 0.0 0.0 3905 0.0 -3.726037E+02 -9.020099E+01 0.0 3.726670E+01 0.0 0.0

S T R E S S E S I N B E A M 3 E L E M E N T S ( C B E A M 3 )

GRID/ STRESS - STRESSES IN LOCAL COORDINATE SYSTEM - ELEMENT-ID GAUSS COMPONENT SXC SXD SXE SXF S-MAX S-MIN M.S.-T M.S.-C0 2901 2901 SX 5.889157E+04 1.087807E+03 -5.671596E+04 1.087807E+03 5.889157E+04 -5.671596E+04 -9.8E-01 -9.6E-01 SY -2.348231E+02 -2.348231E+02 -2.348231E+02 -2.348231E+02 -2.348231E+02 -2.348231E+02 SZ 0.0 0.0 0.0 0.0 0.0 0.0 2902 SX 5.818494E+03 1.902465E+02 -5.438001E+03 1.902465E+02 5.818494E+03 -5.438001E+03 SY -1.096482E+03 -1.096482E+03 -1.096482E+03 -1.096482E+03 -1.096482E+03 -1.096482E+03 SZ 0.0 0.0 0.0 0.0 0.0 0.0 2903 SX 3.235503E+04 6.390266E+02 -3.107698E+04 6.390266E+02 3.235503E+04 -3.107698E+04 SY -6.656523E+02 -6.656523E+02 -6.656523E+02 -6.656523E+02 -6.656523E+02 -6.656523E+02 SZ 0.0 0.0 0.0 0.0 0.0 0.00 3901 3901 SX 5.344819E+04 1.042714E+03 -5.136276E+04 1.042714E+03 5.344819E+04 -5.136276E+04 -9.8E-01 -9.6E-01 SY -3.558532E+01 -3.558532E+01 -3.558532E+01 -3.558532E+01 -3.558532E+01 -3.558532E+01 SZ 0.0 0.0 0.0 0.0 0.0 0.0 3903 SX 3.840311E+04 7.585925E+02 -3.688593E+04 7.585925E+02 3.840311E+04 -3.688593E+04 SY -7.162810E+02 -7.162810E+02 -7.162810E+02 -7.162810E+02 -7.162810E+02 -7.162810E+02 SZ 0.0 0.0 0.0 0.0 0.0 0.0 3904 SX 4.592565E+04 9.006535E+02 -4.412434E+04 9.006535E+02 4.592565E+04 -4.412434E+04 SY -3.759331E+02 -3.759331E+02 -3.759331E+02 -3.759331E+02 -3.759331E+02 -3.759331E+02 SZ 0.0 0.0 0.0 0.0 0.0 0.0

51CHAPTER 4Elements

ExampleID MSC, b3arcbck $ ARCH BUCKLINGSOL 105TIME 10CEND$TITLE = BUCKLING OF AN ARCH WITH CBEAM3 ELEMENTSSUBTI = HALF CIRCLE, PRESSURE LOAD SPC = 10DISP = ALLFORCE = ALLSPCFORCE = ALL$SUBCASE 1LABEL= LOAD CASELOAD = 10SUBCASE 2LABEL= BUCKLING CASEMETHOD = 10$BEGIN BULK$-------2-------3-------4-------5-------6-------7-------8-------9-------0-------EIGRL 10 5$PLOADB3 10 1 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 2 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 3 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 4 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 5 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 6 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 7 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0

S T R A I N S I N B E A M 3 E L E M E N T S ( C B E A M 3 )

GRID/ STRAIN - STRAINS IN LOCAL COORDINATE SYSTEM – ELEMENT-ID GAUSS COMPONENT SXC SXD SXE SXF S-MAX S-MIN M.S.-T M.S.-C0 2901 2901 SX 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 -1.0E+00 SY 8.765757E-17 8.765757E-17 8.765757E-17 8.765757E-17 8.765757E-17 8.765757E-17 SZ 0.0 0.0 0.0 0.0 0.0 0.0 2902 SX 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 SY 5.160202E-17 5.160202E-17 5.160202E-17 5.160202E-17 5.160202E-17 5.160202E-17 SZ 0.0 0.0 0.0 0.0 0.0 0.0 2903 SX 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 SY 6.962979E-17 6.962979E-17 6.962979E-17 6.962979E-17 6.962979E-17 6.962979E-17 SZ 0.0 0.0 0.0 0.0 0.0 0.00 3901 3901 SX 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 -1.0E+00 SY -7.548301E-16 -7.548301E-16 -7.548301E-16 -7.548301E-16 -7.548301E-16 -7.548301E-16 SZ 0.0 0.0 0.0 0.0 0.0 0.0 3903 SX 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 SY -4.543672E-16 -4.543672E-16 -4.543672E-16 -4.543672E-16 -4.543672E-16 -4.543672E-16 SZ 0.0 0.0 0.0 0.0 0.0 0.0 3904 SX 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 1.000000E-01 SY -6.045987E-16 -6.045987E-16 -6.045987E-16 -6.045987E-16 -6.045987E-16 -6.045987E-16 SZ 0.0 0.0 0.0 0.0 0.0 0.0


52

PLOADB3 10 8 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 9 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 10 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 11 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0PLOADB3 10 12 LOCAL 0.0 1.0 0.0 FORCE 1.0 ++ 100. 100. 100.0$CBEAM3 1 1 1 2 21 100 CBEAM3 2 1 2 3 22 100 CBEAM3 3 1 3 4 23 100 CBEAM3 4 1 4 5 24 100 CBEAM3 5 1 5 6 25 100 CBEAM3 6 1 6 7 26 100 CBEAM3 7 1 1 8 31 100 CBEAM3 8 1 8 9 32 100 CBEAM3 9 1 9 10 33 100 CBEAM3 10 1 10 11 34 100 CBEAM3 11 1 11 12 35 100 CBEAM3 12 1 12 13 36 100 $PBEAM3 1 2 .1 .01 .01 0.0 .02 ++ 0.5 0.0 0.0 0.5 -0.5 0.0 0.0 -0.5$MAT1 2 1.0E+7 0.3 .05 .001 0.0 .01 +MAT1-2+MAT1-2 1000. 2000. 3000.$GRID 2 2.58819 9.659258 0.0GRID 3 5.0 8.660254 0.0GRID 4 7.07107 7.07107 0.GRID 5 8.66025 5.0 0.GRID 6 9.65926 2.58819 0.GRID 7 10. 0. 0.$-------2-------3-------4-------5-------6-------7-------8-------9-------0-------GRID 8 -2.588199.659258 0.0GRID 9 -5.0 8.660254 0.0GRID 10 -7.071077.07107 0.GRID 11 -8.660255.0 0.GRID 12 -9.65926 2.58819 0.GRID 13 -10. 0.0 0.0$-------2-------3-------4-------5-------6-------7-------8-------9-------0-------GRID* 21 1.30526 9.91445 ** 0.0GRID* 22 3.82683 9.2388 ** 0.0GRID* 23 6.08761 7.93353 ** 0.0GRID* 24 7.93353 6.08761 ** 0.0GRID* 25 9.2388 3.82683 ** 0.0GRID* 26 9.91445 1.30526 ** 0.0GRID* 31 -1.30526 9.91445 ** 0.0

53CHAPTER 4Elements

GRID* 32 -3.82683 9.2388 ** 0.0GRID* 33 -6.08761 7.93353 ** 0.0GRID* 34 -7.93353 6.08761 ** 0.0GRID* 35 -9.2388 3.82683 ** 0.0GRID* 36 -9.91445 1.30526 ** 0.0$GRID 100 0.0 0.0 0.0$-------2-------3-------4-------5-------6-------7-------8-------9-------0-------SPC1 10 12345 7 13SPC1 10 123456 100$ENDDATA


54

CWSEAM Connector Elements

IntroductionThe functionality of connector elements is enhanced by supporting a seam element to connect two surface patches. To define the seam weld, the user selects two surface patches by their property IDs and specifies the width and the thickness of the seam. The user also has to specify start point “GS” and end point “GE” of the seam segment. These two points do not have to lie on or in between the shell planes. The program will project these two points onto the selected surface patches to find the connecting shell grids.

Inputs The seam connection is modeled by the new CWSEAM and PWSEAM Bulk Data entries and the modified SWLDPRM Bulk Data entry.

Defines a seam element connecting two surface patches.

Format:

Alternate Format:

Example:

CWSEAM A Shell Patch Seam Connection

1 2 3 4 5 6 7 8 9 10CWSEAM EID PID “GRIDID” PIDA PIDB

GS GE

1 2 3 4 5 6 7 8 9 10CWSEAM EID PID “XYZ” PIDA PIDB

XS YS ZS XE YE ZE

CWSEAM 3 17 GRIDID 2305 7116

30024 65467

55CHAPTER 4Elements

Remarks:1. Element ID numbers must be unique with respect to all other element ID numbers.

2. GS and GE define the start and end points of the seam element. At these points and using the value W specified on the PWSEAM entry, surface patches A and B are determined. Points projected onto the surface patches A and B from GS and GE are used to determine the auxiliary points that form faces of a CHEXA element. These auxiliary points are then connected to the physical grids of the patches. The total number of unique physical grids ranges from a possibility of 6 to 32 grids. The auxiliary points must have a projection on patches A and B, but they do not have to lie on patch A or B.

3. A maximum of three shell elements of patch A and three shell elements of patch B can be connected with one CWSEAM element, see Figure 4-3.

Figure 4-3 Connected Shell Elements for a CWSEAM Element

Field Contents

EID Element identification number. (0 < Integer < 100,000,000)

PID Property identification number of a PWSEAM entry. (Integer > 0)

LTYPE Connectivity search type. (Character)If LTYPE=”GRIDID”, location is defined by GS and GE.If LTYPE=”XYZ”, location is defined by two XYZ locations.

PIDA,PIDB Property identification numbers of PSHELL entries defining surface A and B respectively. (Integer > 0)

GS, GE Grid ID’s of piercing points on patches A and B of the Start and End of the seam. (Integer > 0)

XS,YS,ZS Location of the start of the seam in basic coordinate system. (Real or blank)

XE,YE,ZE Location of the end of the seam in basic coordinate system. (Real or blank)

E

S


56

Defines the property of seam connector (CWSEAM) elements.

Format:

Example:

Remarks:1. The length of the seam is the distance between GS and GE. The width of the seam is measured

perpendicular to the length and lies in the plane of the patches A and B (see Figure 4-4). The width is also used to find the projection of the seam on the two patches A and B.

Figure 4-4 Dimensions of a CWSEAM Element

2. If left blank, the thickness will be computed as where is the thickness of patch A and is the thickness of patch B.

PWSEAM Seam Connector Element Property

1 2 3 4 5 6 7 8 9 10

PWSEAM PID MID W T

PWSEAM 7 1 16.

Field Contents

PID Property identification number. (Integer > 0)

MID Material identification number. (Integer > 0)

W Width of the seam. See Remark 1. (Real > 0.)

T Thickness of the seam. See Remark 2. (Real > 0. or blank)

GEGS

T

W

T TA TB+( ) 2⁄= TA

TB

57CHAPTER 4Elements

Overrides default values of parameters for CFAST, CWELD, and CWSEAM connectivity search.

Format:

Example:

SWLDPRM Parameters for CFAST, CWELD, and CWSEAM Connectors

1 2 3 4 5 6 7 8 9 10

SWLDPRM PARAM1 VAL1 PARAM2 VAL2 PARAM3 VAL3 PARAM4 VAL4

PARAM5 VAL5 -etc.-

SWLDPRM GSPROJ 15.0 GSMOVE 2 PRTSW 1

Field Contents

PARAMi Name of the spot weld parameter. Allowable names are listed in Table 4-1. (Character)

VALi Value of the parameter. (Real or Integer; see Table 4-1.)


58

Table 4-1 PARAMi Names and Descriptions

Name Type Default Description

CHKRUN Integer 0, 1, 2 0 Stop the program after the connectivity of connector CWELD elements are generated. 0=abort on first error or run to completion; 1=stop after weld connectivity has been checked; 2=continue run if no errors are found or stop run after all weld connectivity errors have been found.

GMCHK Integer 0, 1, 2 0 For CWELD with PARTPAT format and CWSEAM only. 0=no geometry error checks; 1=check errors of CWELD elements with patch A and patch B tilting toward each other or check errors of the CWSEAM across a cutout or over a corner with patch elements in plane or out of plane; 2=check errors and output all candidate shell elements if an error is encountered. If GMCHK=1 or 2 and an error is detected, the program will loop back to search for next candidate element until a good pair of connection is found or all adjacent elements have been checked. In the latter case, a user fatal message 7595, 7638, or 7667 will be issued. A UFM 7595 is issued if the angle between the normal vectors of the patches at end GS or between the normal vectors of the patches at end GE exceeds the value of GSPROJ; a UFM 7638 is issued if either the length of the seam spans more than three elements or the seam spans a cutout; a UFM 7667 is issued if the angle between the normal vectors of the top patches at GS and GE or between the normal vectors of the bottom patches at GS and GE exceeds GSPROJ or if the angle between the free edges of the shell elements onto which GS and GE are projected is less than 160o (if GSPROJ < 20.0) or (180o-GSPROJ) (if GSPROJ > 20.0).

GSMOVE Integer > 0 0 Maximum number of times GS for the CFAST or CWELD (PARTPAT or ELPAT options only) or GS/GE for the CWSEAM is moved in case a complete projection of all auxiliary points has not been found.

GSPROJ Real 20.0 Maximum angle allowed between the normal vectors of shell A and shell B. The spot weld element will not be generated if the angle between these two normal vectors is greater than the value of GSPROJ. If GSPROJ is set to -1.0, the program will skip the checking of GSPROJ.

59CHAPTER 4Elements

Remarks:1. This entry changes the default settings of control variables for the CFAST, CWELD, and

CWSEAM connector elements. None of the parameters of this entry are required. Only one SWLDPRM entry is allowed in the Bulk Data Section.

2. Connectivity information is generated for the CFAST and CWSEAM elements. For the CWELD, connectivity information is only generated for the PARTPAT, ELPAT, ELEMID, and GRIDID options.

Error Conditions for the CWELD and CWSEAM ElementsThe GMCHK parameter specified in the SWLDPRM Bulk Data entry checks the errors of CWSEAM elements across cutouts or over corners. There are three allowable values of GMCHK. This parameter is also used by CWELD elements with PARTPAT format to check the angle between patches A and B and to find the next candidate element if the angle check fails.

• GMCHK = 0 (Default) Do not check errors

GSTOL Real > 0.0 0.0 For CFAST or CWELD (PARTPAT and ELPAT only), if GSTOL > 0.0 and the distance between GS and the projected point GA or GB is greater the GSTOL, a UFM 7549 is issued and the CFAST or CWELD is rejected. For CWSEAM, if GSTOL > 0.0 and the distance between GS and the projected point GSA or GSB or the distance between GE and the projected point GEA or GEB is greater than the GSTOL, a UFM 7549 is issued and the CWSEAM is rejected.

NREDIA 0 < Integer < 4 0 CFAST or CWELD (PARTPAT and ELPAT) only. Maximum number of times the diameter D is reduced in half in case a complete projection of all points has not been found.

PROJTOL 0.0 < Real < 0.2

0.02 For CFAST or CWELD, tolerance to accept the projected point GA or GB if the computed coordinates of the projection point lie outside the shell element but is located within PROJTOL*(dimension of the shell element forming the patch). For the PARTPAT option for the CWELD or the PROP option for the CFAST it is recommended that PROJTOL=0.0. For the CWSEAM, a projection from GS/GE will always be attempted as if PROJTOL=0.0 and if one cannot be found then the non-zero value of PROJTOL will be used.

PRTSW Integer 0, 1, 2 0 Print diagnostic output. 0=no diagnostic output;1=print diagnostic output to f06 file;2=punch diagnostic output.

Table 4-1 PARAMi Names and Descriptions

Name Type Default Description


60

• GMCHK = 1 Check errors

• GMCHK = 2 Check errors and output all candidate shell elements if there is an error encountered

If GMCHK is turned on, MSC.Nastran will perform the following checking while searching for the projected shell elements. Note that SHSA is the shell element that gets projection from GS on shell A; SHEA is the shell element that gets projection from GE on shell A. Same algorithms are applied to SHSB and SHEB for shell B.

Check the Angle and Find Next Candidate Element for CWELD and PARTPAT Format

If GSPROJ is greater than zero, MSC.Nastran will check the angle between SHSA and SHSB while searching for the projected shell elements. If the angle is greater than GSPROJ, the program will loop back to find next possible projection pair and check the angle between them again, until the angle of the new pair is less than GSPROJ or all candidate elements have been checked.

Check the CWSEAM Across a Cutout or Over a Corner with Elements in Plane1. If SHSA is equal to SHEA, the seam lies within one element. No checks are required.

2. If SHSA and SHEA share two corner grids, these elements are adjacent. No checks are required.

3. If SHSA and SHEA share only one corner grid, the seam is over a corner. There are two exceptions:

• There exists a shell element (SHMA) that shares two corner grids with SHSA and SHEA. Also, either the angle between vector and vector is greater than theta degrees (where theta=160o if GSPROJ < 20.0; theta=180 o -GSPROJ if GSPROJ > 20.0) or the middle point (M) of line segment projects to SHSA, SHMA, or SHEA.

This model is acceptable.

S1S2 E1E4

S2E4

S2

S3

S4

S1 E1⁄

E2

E3

E4M

SHEA

SHSA

SHMA

61CHAPTER 4Elements

This model fails.

• This shared grid is a shell grid of another two different shell elements.

4. If SHSA and SHEA do not share any corner grid, MSC.Nastran will check if there is an element (SHMA) lying between SHSA and SHEA. SHMA must share two corner grids with SHSA and another different one corner grid with SHEA, or vice versa. The following five examples demonstrate the acceptable and failed cases.

• SHMA shares one edge with SHSA and shares one corner grid with SHEA. This case is acceptable.

• SHMA shares one edge with SHEA and shares one corner grid with SHSA. This case is acceptable.

S2

S3

S4

E4

E3

E2

M

SHMA

SHEASHSA

S1 E1⁄

S1 E1⁄

S3

S4

S2

E2 E3

E4

S1

S2

S4

S3

E3

E4E1

E2


62

• SHMA shares one corner grid with SHSA and shares another corner grid with SHEA. An error is detected because the seam spans a cutout.

• SHMA shares one edge with SHSA and shares another edge with SHEA. This case is acceptable.

• There does not exist a single element that shares an edge or corner grid with SHSA or SHEA. An error is detected because the length of the seam spans more than three elements.

S1

S2

S4

S3

E3

E4E1

E2

S1

S2

S4

S3E3

E4E1

E2

S1 S4

S2 S3 E2 E3

E4E1

63CHAPTER 4Elements

Check the CWSEAM Over a Corner with Elements Out of Plane

The GSPROJ parameter is used to check the error of a seam over a corner with SHSA and SHEA not lying on a same plane. If the angle between the shell normal vectors of SHSA and SHEA is greater than

GSPROJ, an error is detected. The default value of GSPROJ is 20o. No angles will be checked if GSPROJ=-1.

Example – A Symmetric Hat Profile (cwseam_hut.dat)This example demonstrates the application of CWSEAM elements to analyze a symmetric hat profile model, see Figure 4-5. Each edge of the hat is connected by 27 CWSEAM elements. The grids with identification numbers 6000 to 6028 and 8000 to 8028 are used as the piercing points to define the seams, see Figure 4-6. A rigid body element (RBE2) is specified to constrain one end of the hat.

Figure 4-5 Hat Profile

S1 S4

S2 S3 E2 E3

E4E1


64

Figure 4-6 Piercing points and Seams

65CHAPTER 4Elements

Line Interface Element

IntroductionLine interface element is used to connect dissimilar meshes along the edges of finite element mesh subdomains. These subdomains have boundaries usually associated with either two-dimensional shell elements or one dimensional beam elements. A set of MPC (Multipoint Constraint) equations are internally generated with the interface boundary grids to enforce the compatibility of displacements and rotations across the interface.

There are perhaps three situations in which finite element analysts want to use the interface element technique to connect two or more independently meshed regions. They are

• Different groups of engineers work almost independently in building finite element models;

• Global-local modeling is used in the analysis, where a fine mesh is required in a particular area due to high stress gradients while the rest of area only needs a coarse mesh, in consideration of the balance of computing resources and the solution accuracy;

• Some regions of a structural model need constant changes or modifications, while the rest of structure needs little or no change.

The purpose of interface element technology is to provide engineers a simple and useful tool in building a more flexible finite element model. The interface element technology is not intended to raise the overall solution accuracy with the existing mesh resolutions of individual subdomains. It is rather how to preserve the solution accuracy in the regions where the finite element results are more interesting to an analyst than in others. The method that we have developed for the line interface element is to achieve primarily the continuity of displacements and rotations across the interface in a way that a measure of their discontinuity is minimized. Since the smoothness (continuity of derivatives) of displacement components across the interface is not enforced by this method, some fluctuation of stresses in the vicinity of the interface could be expected. This stress unevenness or interface effect, however, diminishes quickly in the area away from the interface. This is a phenomenon that can be explained by Saint-Venant’s Principle.

When applying an interface element, the user is asked to specify a boundary on which all the degrees of freedom at the grids are taken as the independent. The degrees of freedom associated with the grids on other boundary or boundaries referenced by the interface element are taken as the dependent and put into the m-set. In the terminology of contact mechanics, the interface boundaries are categorized as the master and slave ones. The nodal points on the master boundary are the independent grids and the nodes on the slave boundary are the dependent grids. An interface element is equivalent to a glued or tied contact that connects the dissimilar meshes.

The conventional way to specify the dependency or master-slave relationship of the interface boundaries is that the boundary with a fine mesh is tied to the one with a coarse mesh. In other words, the boundary with a fine mesh is chosen as a dependent or slave boundary and the one with a coarse mesh as an independent or master boundary. This practice, however, sometimes introduces a seemingly stiff connection along the interface. In this case, it may yield better solutions by switching the dependency relation between the interface boundaries.


66

The line interface element is intended for linear and non-superelement analyses. It should not be used for heat transfer analyses at this moment.

User InterfaceThere are two Bulk Data entries used to define a line interface element. CINTC is the element connection entry which specifies the connectivity of line interface boundaries, represented by Bulk Data entry, GMBNDC.

Bulk Data Entry: CINTC

Defines a line interface element with specified boundaries.

Format:

Example:

Remarks:1. Line interface element identification numbers must be unique with respect to all other line

interface elements.

CINTC Line Interface Element Connection

1 2 3 4 5 6 7 8 9 10

CINTC EID TYPE

LIST=(BID1(INTP1), BID2(INTP2),…, BIDn(INTPn) )

CINTC 1001 GRDLIST

LIST=(101,102(Q),-103(Q),104(L))

Field Contents

EID Element identification number. (0<Integer<100,000,000)

TYPE Connectivity. (Character; Default = "GRDLIST”)

If TYPE=”GRDLIST” or blank (default), the user will specify the boundaries via Bulk Data entry GMBNDC. See Remark 2.

BIDi Boundary curve identification number, referenced to Bulk Data entry GMBNDC. See Remark 2. (Integer 0)

INTPi Interpolation scheme. (Character; Default=”L”)

INTP=”L”: Linear interpolation;

INTP=”Q”: Quadratic interpolation.

67CHAPTER 4Elements

2. There must be at least two BIDi specified. If all BIDi are positive, by default, the degrees of freedom associated with the grids on the boundary represented by the first BID will be taken as the independent (n-set), and the degrees of freedom with the grids on the rest of boundaries are taken as the dependent (m-set). If there is a single negative BID, the degrees of freedom associated with the grids on the boundary represented by this BID will be taken as the independent (n-set), and the rest of the degrees of freedom with other boundaries are used as the dependent (m-set). If there are two or more negative BIDs, the degrees of freedom with the first negative one will be taken as the independent.

3. Forces of multipoint constraints may be recovered with the MPCFORCE Case Control command.

4. The m-set degrees of freedom specified on the boundary grids by this entry may not be specified by other entries that define mutually exclusive sets.

Bulk Data Entry: GMBNDC

This is an existing Bulk Data entry originally designed for p-element edges along a curve interface. If it is referenced by Bulk Data entry CINTC, the value of Field ENTITY must be GRID.

Applications of Line Interface Element

Line Interface Element

A line interface element is a computational entity which consists of two or more interface boundaries along a virtual common interface curve. An interface boundary coincides with an edge of a finite element mesh subdomain. Primarily, an interface boundary is defined by a set of sequentially listed grid points, as specified by Bulk Data entry GMBNDC. On each boundary, there are at least two grids for a linear interpolation scheme and three for a quadratic one.

There is a dependency (or master-slave) relationship among the interface boundaries. This dependency relation is used to internally generate MPC equations between the independent and dependent degrees of freedom. At each grid point on a boundary, there are six degrees of freedom, three translational and three rotational. An interface boundary is called the dependent if all the degrees of freedom related to its grids are put in the m-set. An independent boundary is the one that all the degrees of freedom related to its grids are assigned to the n-set. There is only one independent boundary in an interface element.

In terms of element characteristics, an interface element is similar to a rigid or constraint element, such as RBE1 and RSPLINE. Unlike rigid elements, however, its processing is not selectable by Case Control command RIGID. In other words, only the linear elimination method is applied to this element. The degrees of freedom associated to the grids on a dependent interface boundary may not be simultaneously assigned dependent by other rigid, constraint or connection elements, a multipoint constraint or another interface element. On the other hand, the degrees of freedom with the grids on an independent interface boundary can be made dependent by another element or a multipoint constraint. This recursive dependent-independent relationship should be carefully examined to avoid potential conflicts when an interface element interacts with a multipoint constraint, a rigid, constraint or connection element, or another interface element. In addition, the dependent set (m-set) specified by the dependent interface boundary may not be specified on other entries that define mutually exclusive set (See “Degree-of-Freedom Set Definitions (p. 888) in the MSC.Nastran Quick Reference Guide. AUTOMSET can be used


68

with the interface element. It is designed to handle potentially ill-conditioned matrix by reassigning

dependent set (m-set) from the existing MPC equations, based on its rank deficiency. It needs further verifications to see how well the interface element works with AUTOMSET.

Line Interface Boundary

An interface element has two or more boundaries. Each boundary is defined primarily by a set of grid points listed sequentially from the initial grid through the final one, as specified by Bulk Data entry GMBNDC with Field ENTITY=”GRID”. All the boundaries in a line interface element must have their initial grids at the starting end and final grids at the terminal end of the interface.

One of the interface boundaries is specified as the independent by Bulk Data entry CINTC. If there are three or more boundaries in an interface element, the boundaries are internally grouped in pairs by the dependent-independent relationship. There are N-1 pairs of boundaries where N is the total number of boundaries with the interface element. MSC.Nastran generates the MPC equations between the dependent and independent grids on the pair of boundaries.

A boundary can be either open, i.e., the initial and final grids are different grids, or closed, i.e., the initial and final grids are the same grid, as shown in Figure 4-7. For a closed boundary, we have GRIDI=GRIDF in GMBNDC. There is a requirement for the minimum number of grids on a boundary. There must be at least two grids for the linear and three for the quadratic interpolation scheme.

Figure 4-7 Open and Closed Boundaries

Both dependent and independent open boundaries may share either initial or final grids or both of them. By assigning the same end grid to a pair of boundaries, the user has more flexibility to applying the interface element when one interface element connects or intersects with another interface element. This rule, however, may not apply to the closed boundaries.

A pair of interface boundaries can be either matching or non-matching, as shown in Figure 4-8. The non-matching boundaries have at least one dangling end grid. The interface line integration is taken along the common arc-length shared by both boundaries. Redundant dangling grids, as shown in Figure 4-9, are excluded from the processing of interface element.

Rmg[ ]

GRIDI GRIDF

Open Boundary

GRIDI=GRID

Closed Boundary

GRIDI GRIDF

Open Boundary

GRIDI=GRID

Closed Boundary

69CHAPTER 4Elements

Figure 4-8 Matching and Non-matching Boundaries

Figure 4-9 Redundant Dangling Grids on Boundary

For an interface element with closed boundaries, special caution must be taken when selecting the initial grids. Since the initial grid can be any one on a closed boundary, it is required that the two initial grids on the dependent-independent closed boundaries be as closed as possible, as shown in Figure 4-10. In other words, a selection of an initial grid being a redundant grid in terms of the other initial grid is not supported. When one of the boundaries is open, this rule does not apply.

Matching Boundaries

Non-matching Boundaries and Integration Path

Matching Boundaries

Non-matching Boundaries and Integration Path

Redundant Dangling Grids


70

Figure 4-10 Selection of Initial Grids on Closed Boundaries

When the interface consists of curved boundaries, as shown in Figure 4-11, the interface boundary grids should be aligned along the actual line of structural geometry. At this release we have not implemented a capability that enables MSC.Nastran to check the integrity of interface boundary geometries. The existence of awry grids in the boundary grid list will lead to some interface malfunction without notice.

GRIDIA

GRIDIB GRIDIB

GRIDIA

Acceptable Selection of Initial Grids GRIDIA and GRIDIB

Unsupported Selection of Initial Grids GRIDIA and GRIDIB

71CHAPTER 4Elements

Figure 4-11 Curved Boundaries

Example and ResultsAs shown in Figure 4-12, two independently meshed plates are connected by a line interface element. The plate structure is constrained at one edge and subject to a pressure load. The interface element is defined by Bulk Data entries, CINTC and GMBNDC, as shown in Listing 4-4. The solution results of displacement and von Mises stress distributions are presented in Figure 4-13 and Figure 4-14, respectively.

Listing 4-4 Interface Element Definition

CINTC 1001LIST=( 101, 102 )GMBNDC 101 67 107GRID 72 77 82 87 92 97 102GMBNDC 102 6 66GRID 12 18 24 30 36 42 4854 60

Actual structure geometry

Finite element model on boundary A

Finite element model on boundary B


72

Figure 4-12 Two Plates Connected by Line Interface Element

Figure 4-13 Displacement

73CHAPTER 4Elements

Figure 4-14 von Mises Stress


74

Arbitrary Beam Cross-Section

IntroductionArbitrary beam cross-section, ABCS, capability has been implemented in MSC.Nastran 2005 via Bulk Data entries, PBRSECT and PBMSECT. In this new version of MSC.Nastran, ABCS has enhancements in the area of cross-section outline display, stress data recovery and design optimization. In addition, ABCS algorithm has become the default formulation for pre-defined shapes of PBARL/PBEAML.

BenefitsTraditionally, MSC.Nastran recovers axial stresses at four ‘extreme’ points of the BAR/BEAM element cross-section. Although this may be acceptable on typical usage scenario for 1D element, the contribution of torsion and shear forces are simply assumed to be very minor and ignored. In MSC.Nastran 2005 r3, for the first time a venue is provided to perform complete stress recovery for the whole cross-section with torsion and shear effect included. The stresses recovered can be post-processed as familiar GPSTRESS via SURFACE for each distinct cross-section. In addition, MSC.Nastran SOL 200 users can also perform optimization with the ‘screened’ stresses of BAR/BEAM elements.

Furthermore, an alternative formulation using ABCS logic for PBARL/PBEAML is also offered in MSC.Nastran 2005 r3. In all previous MSC.Nastran releases, the equations used for PBARL/PBEAML were constructed under the assumption that the cross-sections are thin-walled. The properties, especially J, K1, K2, Cwa and Cwb, computed by such equations may have significant error. With the alternative formulation as default for PBARL/PBEAML, the correct properties are computed regardless if the section is thin-walled or not.

ABCS enhancements includes the following items

1. Output a PostScript, ‘.ps’, file for displaying the outline of cross-section. Also included in the ‘.ps’ file is the markers of center of gravity and shear center and sectional properties.

2. Generation of nodal and connection bulk data entries of FEM discretization for arbitrary beam cross-section

3. Stress data recovery for whole cross-section with contribution from torsion and shear included. In addition, ‘screened’ version of full stress recovery is also available which has the maximum/minimum direct stresses and max von Mises stress.

4. New RTYPE=ABSTRESS for ‘screened’ stresses can be utilized as constraints in optimization.

5. Alternative formulation for PBARL/PBEAML – selectable via SYSTEM(606), or TWBRBML on MDLPRM

InputsMinimal user input is required to control the new features. For each item of the ABCS enhancements, its input is discussed in following sections.

http://www.cs.wisc.edu/~ghost/

75CHAPTER 4Elements

Post-Script File Generation

PARAM,ARBMPS,YES (default)

The default value for parameter ARBMPS is ‘YES’ which flags the generation of PS file. The PS file has the name of ‘mydeck.ps’ for an input file of ‘mydeck.dat’. The PS file includes following important information.

• outline of the cross-section

• marker for the location of center of gravity. For ABCS via PBMSECT, marker for the location of shear center is also shown.

• Properties of the cross-section

‘PARAM,ARBMPS,NO’ turns off the generation of PS file.

Generation of Finite Element Model, FEM, for the Cross-Section

PARAM,ARBMFEM,YES (default)

The default value for parameter ARBMFEM is ‘YES’ which flags the generation of file(s) of FEM of each distinct cross-section. ‘PARAM,ARBMFEM,NO’ switches off the generation of ‘.bdf’ file for FEM of cross-section.

Stress recovery for whole cross-section The required input for ABCS logic to perform stress recovery for whole cross-section is the element force. Hence, to activate stress recovery for whole cross-section, the following input must be present in the input file.

1. ELFORCE (or simply FORCE) output request in the case control and

2. ‘PARAM,ARBMSS,YES’ (Default=NO) as bulk data entry

Due to the potential of a huge amount of output, these stresses are only available in OUTPUT2 format. In addition, the stresses recovered are prepared in a pattern consistent with GPSTRESS via SURFACE. The recovered stresses for each grid of FEM of cross-section are σx, τxy, τzx, principal stresses and von Mises stress. Note that recovered ABCS direct stresses are placed in stress tensor consistent with direct stress of SURFACE. The following table shows where recovered direct stresses in stress tensor.

Stress Tensor Recovered ABCS DIrect Stress

σx σx

σy τxy

σz

τxy τzx


76

As a data reduction process, max/min of , , τzx and max von Mises stress of each station of every

selected element are collected from stress recovery for the whole cross-section and is available in print file (f06). These collected stresses are called ‘screened’ stresses which can be utilized as design response for SOL 200 job.

New response type RTYPE=ABSTRESS is available on DRESP1 for using ‘screened’ stresses of BAR/BEAM elements as design response. An example for the new response type is as follows

DRESP1,23,ABSVM,ABSTRESS,PBMSECT, , 9, , 32

where max von Mises stress (item code 9) of all elements refers to PBMSECT,32 is selected as design response.

Alternative formulation for PBARL/PBEAML The default formulation is now set to use Finite Element Method to compute sectional properties. The alternate formulation will be active under the following conditions

1. GROUP field of PBARL/PBEAML must be either left BLANK or has “MSCBML0” as input

2. job run on a short-word (32 bits) machine

To switch back to the beam library equations, use either ‘NASTRAN twbrbml=1’ in executive control file or ‘mdlprm,twbrbml,1’ in bulk data.

OutputPost-Script file for the outline of ABCS A ‘.ps’ file for all PBRSECT/PBMSECT of a job will be available at the conclusion of a job. GhostScript/GSview, available for download at http://www.cs.wisc.edu/~ghost/, can be utilized for viewing of PostScript file.

Generation of FEM for cross-sections The file generated has the following naming convention

AAA_xxyyy_zz.bdf

where AAA – By default, it assume the input file name. To alter AAA to a name other than input file name, use

ASSIGN opcase=’any character string’ $

τyz

τzx

Stress Tensor Recovered ABCS DIrect Stress

σ τxy

77CHAPTER 4Elements

As naming implies, there should be as many files holding FEM of cross-sections as PBRSECT/PBMSECT Bulk Data entries at conclusion of a job. Note that PBMSECT supports constant section beam only.

Stress output for the whole cross-section The file holding stresses for whole cross-section in OP2 format has same naming convention as the FEM for cross-section. For stresses, the file has the extension of ‘.op2’ instead.

For ‘screened’ stresses, an output example is shown as follows

New response type, ABSTRESS, for optimization An example of output for ABSTRESS sensitivity is shown as follows

Alternate Formulation for PBARL/PBEAML

A message as follows will be available in f06 to indicate which method is used to compute sectional properties for PBARL/PBEAML.

If alternative formulation is utilized

If original beam equations are utilized

xx character string of ‘BR’ for PBRSECT and ‘BM’ for PBMSECT

yyy ID of PBRSECT or PBMSECT

zz station ID. ‘01’ for end A of PBMSECT. No zz section for PBRSECT.

1 BEAM LIBRARY TEST CASE BLO MAY 29, 2005 MSC.NASTRAN 5/27/05 PAGE 10 TRANSVERSE TIP LOAD 0 SUBCASE 1 S T R E S S E S I N B E A M E L E M E N T S ( S C R E E N E D ) AXIAL SHEAR-XY SHEAR-XZ VON MISES ELEMENT-ID STATION MAX MIN MAX MIN MAX MIN MAX 2 0.000 2.206054E+00 -2.254727E+00 2.075935E-01 -2.175731E-02 1.687584E-01 -1.681947E-01 2.258905E+00 2 1.000 6.117611E-17 -6.315223E-17 2.075935E-01 -2.175731E-02 1.687584E-01 -1.681947E-01 3.694130E-01

-------------------------------------------------------------------------------------------------------------------------------- DRESP1 ID= 323 RESPONSE TYPE= ABSTRESS ELEM ID= 2 COMP NO= 9 SEID= 0 SUBCASE RESP VALUE DESIGN VARIABLE COEFFICIENT DESIGN VARIABLE COEFFICIENT -------------------------------------------------------------------------------------------------------------------------------- 1 2.2589E+00 31 DBOXGS 0.0000E+00 232 DBOXCP -2.2693E+00 2 2.0246E+00 31 DBOXGS 0.0000E+00 232 DBOXCP -1.7749E+00

*** USER INFORMATION MESSAGE 4379 (IFP9A) THE USER SUPPLIED PBEAML/PBMSECT BULK DATA ENTRIES ARE REPLACED BY THE FOLLOWING PBEAM ENTRIES. CONVERSION METHOD FOR PBARL/PBEAML - FINITE ELEMENT METHOD.

*** USER INFORMATION MESSAGE 4379 (IFP9A) THE USER SUPPLIED PBARL/PBRSECT BULK DATA ENTRIES ARE REPLACED BY THE FOLLOWING PBAR ENTRIES. CONVERSION METHOD FOR PBARL/PBEAML - BEAM LIBRARY EQUATIONS.


78

If both formulations are utilized

Guidelines1. Finite element formulation for computing cross-sectional properties is considered more accurate,

especially for thin-walled cross-sections, across wider spectrum of beam cross-sections. Hence, it is the default formulation for PBARL/PBEAML. However, there is a minor performance penalty that came with the accuracy.

2. Use only matching ‘.bdf’ and ‘.op2’ files from the same job to visualize the stress pattern,

3. For SOL 200 optimization jobs, finite element formulation for PBARL/PBEAML is highly recommended due to the potential that new design can cross the thin-/thick-walled line.

Limitations1. Finite element formulation for arbitrary beam cross-section is available only on short-word

machines. Hence, the alternative formulation for PBARL/PBEAML using finite element method is supported only on short-word machine. Typically, Cray is a long-word machine and finite element formulation for arbitrary beam cross-section is not supported.

2. Arbitrary beam cross-section supports constant section for beam elements via PBMSECT. Cross-sectional variation from end A to end B is not supported via PBMSECT. However, tapered cross-section is supported via PBEAML even if finite element formulation is utilized.

3. Stress recovery for the full cross-section is available only for Static (SOL 101), Modes (SOL 103) and Optimization (SOL 200).

4. Stress recovery for the full cross-section is available for the first cycle of a SOL 200 job.

5. For SOL 200 jobs, the stresses recovered can be successfully post-processed with the companion ‘.bdf’ file only if the properties have no discrepancy between analysis and design model.

ExampleA simple file, zbm5a1, with two PBMSECT entries is utilized here to demonstrate the features implemented. Double box cross-section is modeled with PBMSECT,31 using FORM=GS and PBMSECT,32 using FORM=CP. The overall width of PBMSECT,31 and the thickness of outer wall of PBMSECT,32 are selected as design variables. Some key bulk data entries are shown as follows

*** USER INFORMATION MESSAGE 4379 (IFP9A) THE USER SUPPLIED PBARL/PBRSECT BULK DATA ENTRIES ARE REPLACED BY THE FOLLOWING PBAR ENTRIES. CONVERSION METHOD FOR PBARL/PBEAML – MIXED FORMULATION

79CHAPTER 4Elements

Zbm5a1 uses default value for PARAM,ARBMPS and PARAM,ARBMFEM. Hence, output files are

1. zbm5a1.ps – the content is shown in Figure 4-15 and Figure 4-16.

2. zbm5a1_bm31_01.bdf - FEM for PBMSECT,31 shown as Table 4-2

3. zbm5a1_bm32_01.bdf – FEM for PBMSECT,32 shown as Table 4-3.

$$ DBOX section using pbmsect with GS optionPOINT 111 0.0 0.0 POINT 112 20.0 0.0 POINT 113 20.0 19.4 POINT 114 0.0 19.4 POINT 125 1.0 1.0 POINT 126 10.0 1.0 POINT 127 10.0 18.4 POINT 128 1.0 18.4 POINT 132 11.0 1.0 POINT 133 19.0 1.0 POINT 134 19.0 18.4 POINT 135 11.0 18.4 $SET1 111 111 THRU 114 SET1 122 128 127 126 125 128SET1 133 132 133 134 135 $pbmsect 31 10 GS OUTP=111,inp=122,inp=133DESVAR 31 DBOXGS15.00.0160.0DVPREL1112pbmsect31 W 31 1.0$$ DBOX section using pbmsect with CP option$DESVAR 232 DBOXCP 1.00 0.01 3.0DVPREL1 312 pbmsect 32 T 232 1.0$POINT 201 0.5 0.5POINT 202 10.5 0.5POINT 203 19.5 0.5POINT 204 19.5 18.9POINT 205 10.5 18.9POINT 206 0.5 18.9POINT 224 10.5 10.0SET1 201 201 THRU 206SET1 202 202 224 205pbmsect 32 10 CP OUTP=201,T=1.0,BRP=202, T(11)=[1.2,PT=(202,224)],T(12)=[1.2,PT=(224,205)]


80

Figure 4-15 Outline and properties of PBMSECT,31

81CHAPTER 4Elements

Figure 4-16 Outline and properties for PBMSECT,32

Table 4-2 FEM for PBMSECT,31 (abridged)


82

Table 4-3 FEM for PBMSECT,32(abridged)

GRID and CTRIA6 entries for PBMSECT 31 BEGIN

NUMBER OF GRID = 683 NUMBER OF CTRIA6= 262

CTRIA6 10001 10000 10013 10038 10211 10033 10273 10212CTRIA6 10002 10000 10065 10082 10399 10013 10288 10213CTRIA6 10003 10000 10067 10161 10557 10014 10294 10215..CTRIA6 10260 10000 10002 10054 10335 10181 10336 10680CTRIA6 10261 10000 10003 10055 10338 10115 10339 10668CTRIA6 10262 10000 10001 10056 10341 10196 10342 10683GRID* 10001 0.00000000D+00* 0.00000000D+00 GRID* 10002 2.00000000D+01* 0.00000000D+00 GRID* 10003 2.00000000D+01* 1.93999996D+01 ..GRID* 10682 1.00898438D+01* 1.90601559D+01 GRID* 10683 6.25000000D-01* 0.00000000D+00

GRID and CTRIA6 entries for PBMSECT 31 END

83CHAPTER 4Elements

The output of stress recovery of whole cross-section is available in OUTPUT2 format. For zbm5a1, the files are

1. zbm5a1_bm31_01.op2 – stress recovery for all elements referencing PBMSECT,31

2. zbm5a1_bm32_01.op2 – stress recovery for all elements referencing PBMSECT,32

Contour plots with data from zbm5a1_bm31_01.op2 are shown in the following figures. Axial stress, shear stress in xy, shear stress in zx and von Mises stress are shown in Figure 4-17, Figure 4-18, Figure 4-19 and Figure 4-20, respectively. In these figures, the number after ‘Grid Point Stresses’ has XXYY format where

GRID and CTRIA6 entries for PBMSECT 32 BEGIN NUMBER OF GRID = 629 NUMBER OF CTRIA6= 238

CTRIA6 20001 20000 20017 20064 20196 20009 20612 20197CTRIA6 20002 20000 20048 20113 20332 20017 20290 20198CTRIA6 20003 20000 20018 20007 20199 20027 20227 20200..CTRIA6 20236 20000 20155 20059 20322 20154 20607 20513CTRIA6 20237 20000 20003 20045 20282 20049 20597 20292CTRIA6 20238 20000 20001 20054 20306 20181 20307 20628GRID* 20001 0.00000000D+00* 1.93999996D+01 GRID* 20002 0.00000000D+00* 0.00000000D+00 GRID* 20003 1.05000000D+01* 0.00000000D+00 ..GRID* 20628 0.00000000D+00* 1.87937489D+01 GRID* 20629 1.41625004D+01* 5.00000000D-01

GRID and CTRIA6 entries for PBMSECT 32 END

Note: The GRID and CTRIA6 numbering are based on the processing sequence of the arbitrary beam cross-section. The first GRID (or CTRIA6) of the first cross-section processed will have ID of 10001. The first GRID of 2nd cross-section processed has ID of 20001.

XX EID of a BAR/BEAM element.

YY station ID. ‘00’ for end A. ‘01’ for end B if no intermediate station.


84

Figure 4-17 Axial Stress of End A of CBEAM,1 referencing PBMSECT,31

85CHAPTER 4Elements

Figure 4-18 Shear Stress in XY of End A of CBEAM,1 referencing PBMSECT,31


86

Figure 4-19 Shear Stress in ZX of End A of CBEAM,1 referencing PBMSECT,31

87CHAPTER 4Elements

Figure 4-20 von Mises Stress of End A of CBEAM,1 referencing PBMSECT,31

The ‘screened’ stresses which can be utilized in optimization is shown as follows.


88

1 BEAM LIBRARY TEST CASE BLO JUNE 16, 2005 MSC.NASTRAN 6/15/05 PAGE 17 TRANSVERSE TIP LOAD 0 SUBCASE 1 S T R E S S E S I N B E A M E L E M E N T S ( S C R E E N E D ) AXIAL SHEAR-XY SHEAR-XZ VON MISES ELEMENT-ID STATION MAX MIN MAX MIN MAX MIN MAX 2 0.000 2.206054E+00 -2.254727E+00 2.075935E-01 -2.175731E-02 1.687584E-01 -1.681947E-01 2.258905E+00 2 1.000 6.117611E-17 -6.315223E-17 2.075935E-01 -2.175731E-02 1.687584E-01 -1.681947E-01 3.694130E-011 BEAM LIBRARY TEST CASE BLO JUNE 16, 2005 MSC.NASTRAN 6/15/05 PAGE 18 LATERAL TIP LOAD 0 SUBCASE 2 S T R E S S E S I N B E A M E L E M E N T S ( S C R E E N E D ) AXIAL SHEAR-XY SHEAR-XZ VON MISES ELEMENT-ID STATION MAX MIN MAX MIN MAX MIN MAX 2 0.000 2.023472E+00 -2.023472E+00 8.784060E-02 -8.598299E-02 1.045674E-01 -8.338179E-03 2.024639E+00 2 1.000 2.304938E-16 -2.304893E-16 8.784060E-02 -8.598299E-02 1.045674E-01 -8.338179E-03 1.998240E-01


Ch. :

5 Dynamics and Superelements

! Efficiency Enhancements to MTRXIN Module for Handling DMIG Data, 90

! Enhancements to BSETi/BNDFIXi and CSETi/BNDFREEi Bulk Data Entry Processing, 91

! Enhancements to MATMOD Module Option 16, 92

! Enhancements to External Superelement Usage Via EXTSEOUT Case Control Command, 97

! Changes to Rotordynamic for MSC.Nastran 2005 r3, 101


90

Efficiency Enhancements to MTRXIN Module for Handling DMIG DataThe MTRXIN module generates matrix data blocks from DMIG data resident on a MATPOOL-type data block. If the matrix generation is handled in memory, then the processing is very efficient. However, if it involves out-of-memory operations, then the processing efficiency decreases, especially for large matrices and particularly so for large symmetric matrices.

Enhancements have been made to the MTRXIN module in MSC.Nastran 2005 r3 to improve out-of-memory processing. With these enhancements, decreases in CPU times of 50% to 65% for large rectangular matrices and 20% to 35% for large symmetric matrices have been observed. In general, the larger the matrix size, the greater will be the decrease in the CPU time.

91CHAPTER 5Dynamics and Superelements

Enhancements to BSETi/BNDFIXi and CSETi/BNDFREEi Bulk Data Entry ProcessingBNDFIX/BNDFIX1 and BNDFREE/BNDFREE1 Bulk Data entries were introduced in MSC.Nastran 2004 as alternatives to the existing BSET/BSET1 and CSET/CSET1 Bulk Data entries, respectively. However, the program did not allow the new Bulk Data entries to be used in conjunction with their alternate forms in the same Bulk Data file. This restriction has been removed in MSC.Nastran 2005 r3, thereby allowing mixed usage of the BNDFIXi and BNDFREEi entries with their alternatives of BSETi and CSETi entries in the same Bulk Data file. This is also reflected in the enhanced description of these Bulk Data entries in the MSC.Nastran Quick Reference Guide.


92

Enhancements to MATMOD Module Option 16

IntroductionOption 16 of the MATMOD module was designed to put a matrix into DMIG format in a MATPOOL-type data block as well as to optionally generate DMIG punched output. This option is very useful, particularly in analyses involving part and external superelements. However, its implementation suffers from several deficiencies and inconveniences as explained below.

1. Only G-size matrices are handled. In particular, if the input matrix is square or symmetric, both the rows and columns must be of G-size. If it is a rectangular matrix, the rows must be of G-size, while the columns are regarded as just sequential entities.

2. The rows and columns of the input matrix must be in external sort. This is a particularly inconvenient requirement since it requires re-arrangement of its rows and columns that are normally in internal sort. This requirement forces the use of Option 9 of the MATGEN module to generate a transformation matrix to convert from internal sort to external sort and then employing this transformation matrix to perform the required transformation of the desired matrix before it can be used as input to the MATMOD module.

3. The name of the matrix in the DMIG output is the same as the name of the data block containing the input matrix. There is no way to give an arbitrary name to the matrix in the DMIG output.

4. Even if only the DMIG punched output is desired, the MATPOOL-type output data block still has to be generated even though it may never be used thereafter.

Major enhancements have been made to Option 16 of the MATMOD module in order to overcome the above deficiencies and inconveniences. These enhancements utilize an additional input data block and several additional parameters to accomplish their purpose. These enhancements are explained below.

1. The size of the input matrix is no longer restricted to G-size. Instead, any size corresponding to any valid displacement set of the User Set (USET) table is allowed. Also, for the first time, Option 16 can handle rectangular matrices wherein the columns correspond to a displacement set and are not necessarily regarded as sequential entities. This allows Option 16 to handle the more general case of rectangular matrices wherein the rows and columns correspond to different displacement sets.

2. The rows and columns of the input matrix need not be in external sort. They can be in internal sort which is their normal arrangement.

3. The name of the matrix in the DMIG output need not be the same as the name of the data block containing the input matrix. An arbitrary name can be specified for the matrix in the DMIG output.

4. The MATPOOL-type output data block need not be generated if only the DMIG punched output is desired.


UsageAs indicated earlier, the above enhancements are accomplished by using one additional input data block and several additional parameters. The new usage of Option 16 is as follows:

Input data block USET and the parameters P3, P13, P14 and P15 represent additions as part of the enhancements. The default values for these additional parameters have been chosen such that legacy files employing the old usage of Option 16 will continue to give the same results as before. A full description of the enhanced Option 16 usage is given in the Appendix.

ExampleThe power of the enhancements is well illustrated by the example given under the description of Option 16 in the Appendix. This example clearly shows that the enhanced features of Option 16 result in much simpler and more efficient DMAP programs than was the case in earlier versions.

Enhancements to MATMOD Module

Option=16

Put matrix into DMIG format in a MATPOOL-type data block and/or generate DMIG punched output.

Format:

Input Data Blocks:

Output Data Block:

MATMOD MATRIX,EQEXIN,USET,,,/MATPOOLX,/16/P2/P3/P4////////P12/P13/P14/P15 $

MATMOD MATIN,EQEXIN,USET,,,/MATPOOLX,/16/PUNCHFLG/SORTFLG/TYPOUT////////CONTCHR/DMIGNAME/ROWSETNM/COLSETNM $

MATIN Matrix to be converted to DMIG format. (Real or complex). See Remark 1.

EQEXIN EXEQXIN table from module GP1. See Remark 7.

USET USET table from module GP4 or GPSP. See Remark 8.

MATPOOLX MATPOOL-type table data block containing MATIN in DMIG format. See Remark 9.


94

Parameters:

Remarks:1. The program checks to ensure that the form of MATIN is either 1 (square), 6 (symmetric) or 2

(rectangular). If this is not so, the program issues a warning message and proceeds without generating any output from this call to the MATMOD module.

2. If the default value of 0 for SORTFLG is used, the rows of MATIN must be of G-size. If MATIN is square or symmetric, its columns must also be of G-size. Further, the default value of 0 for SORTFLG also assumes that the rows and columns of MATIN are in external sort. In order to accomplish this, it is necessary to first generate a transformation matrix via MATGEN module Option 9 and then employ this matrix to transform the rows and columns of MATIN from internal sort to external sort. (This is illustrated in the Example shown below.)

PUNCHFLG Input-integer-default=0. If PUNCHFLG is non-zero, then DMIG punched output will be generated. See Remark 9.

SORTFLG Input-integer-default=0. The default assumes that the rows (and columns, if applicable) of MATIN are in external sort. If SORTFLG is non-zero, then it is assumed that they are in internal sort. See Remark 2.

TYPOUT Input-integer-default=0. The default sets the DMIG precision to machine precision. The default maybe overridden by specifying the following:

1 Real single precision format2 Real double precision format3 Complex single precision format4 Complex double precision format

CONTCHR Input-character-default=blank. Continuation characters to be used for DMIG punched output. Only the first two characters of the non-blank mnemonic are used for the continuation string. See Remark 3.

DMIGNAME Input-character-default=blank. The default will cause the name of the MATIN input data block to the used for the matrix name in the DMIG output. A non-blank name will cause that specified name to be used for the matrix name in the DMIG output.

ROWSETNM Input-character-default=blank. The default assumes that the rows of MATIN are of G-size. Any non-blank mnemonic specifies the displacement set for the rows. See Remarks 4, 5 and 6.

COLSETNM Input-character-default=blank. If the form of MATIN is 1 (square) or 6 (symmetric), then the default assumes that the displacement set for the columns is the same as that of the rows. If the form of MATIN is 2 (rectangular), then the default (or a mnemonic of ‘H’) assumes that the columns do not represent any displacement set, but just sequential entities. Any non-blank mnemonic other than ‘H’ specifies the displacement set for the columns. See Remarks 4, 5 and 6.


3. If non-blank continuation characters are specified for CONTCHR, then a maximum of 99,999 DMIG entries can be generated for any single matrix. If this maximum number is exceeded, the program terminates the job with a fatal error.

4. The program checks to ensure that the number of rows and columns of MATIN correspond to the displacement sets specified (or implied) by ROWSETNM and COLSETNM. If this condition is not satisfied, the program issues a warning message and proceeds without generating any output from this call to the MATMOD module.

5. If the form of MATIN is either 1 (square) or 6 (symmetric), then the IFO field on the generated DMIG entry is set to 1 or 6. If the form is 2 (rectangular), then IFO is set to 2 if a displacement set is specified (or implied) for COLSETNM. Otherwise, IFO is set to 9. (If the form is 6, only the terms in one triangle are output. The MTRXIN module, which converts DMIG data in MATPOOL-type data blocks into matrices, fills in the other triangle for symmetric matrices.)

6. The rows of the DMIG entry are always labeled with the appropriate grid/scalar IDs and component numbers. If a displacement set is specified (or implied) for COLSETNM, then the columns of the DMIG entry are also labeled with the appropriate grid/scalar IDs and component numbers. Otherwise, the columns of the DMIG entry are labeled sequentially, starting with unity.

7. The EQEXIN input data block may not be purged.

8. The USET input data block may be purged if (a) the default value of 0 is used for SORTFLG or (b) the displacement set specified (or implied) by ROWSETNM is ‘G’ and the displacement set specified (or implied) by COLSETNM is either ‘G’ or the columns are just sequential entities.

9. The MATPOOLX output data block may be purged if PUNCHFLG is specified as non-zero and only the DMIG punched output is desired.

Example:

Generate DMIG punched output for the boundary stiffness matrix KAA, the boundary load matrix PA and the matrix GMN (representing the MPC/rigid element equations) for an external superelement. The KAA DMIG entry is to be named KAAEXTSE, the PA DMIG entry is to be named PAEXTSE and the GMN DMIG entry is to be named GMNEXTSE.

The DMAP shown illustrates the usage of Option 16 using input matrices in internal sort (capability available in MSC.Nastran 2005 r3 and subsequent releases) as well as using input matrices in external sort (only usage possible in pre-MSC.Nastran 2005 r3 releases). It can be seen that the DMAP for the former case is much simpler and more efficient than for the latter case.

It should be pointed out here that, if the internal and external sorts are different, the DMIG output resulting from the two scenarios shown below will “appear” to be different. This is because the matrix elements will be output in different order, but their values will be the same. The DMIG output from the two scenarios will yield identical matrices if they are used in turn by the MTRXIN module to re-generate the matrices.

DMAP using input matrices in internal sort (MSC.Nastran 2005 r3 and subsequent releases)TYPE PARM,,I,N,PUNCHFLG=1 $ GENERATE DMIG PUNCHED OUTPUT


96

TYPE PARM,,I,N,SORTFLG=1 $ INPUT MATRICES ARE IN INTERNAL SORT

DMAP using input matrices in external sort (pre-MSC.Nastran 2005 r3 releases)TYPE PARM,,I,N,PUNCHFLG=1 $ GENERATE DMIG PUNCHED OUTPUT$ EXPAND BOUNDARY MATRICES TO G-SIZEUMERGE1USET,KAA,,,/KAAGG/’G’/’A’ $ EXPAND ROWS AND COLUMNSUMERGE1USET,PA,,,/PAG/’G’/’A’//1 $ EXPAND ROWSUMERGE1USET,GMN,,,/GMNGN/’G’/’M’//1 $ EXPAND ROWSUMERGE1USET,GMNGN,,,/GMNGG/’G’/’N’//2 $ EXPAND COLUMNS$ GET G-SIZEPARAMLUSET//’TRAILER’/2/S,N,GSIZE $$ GENERATE MATRIX TO TRANSFORM FROM INTERNAL SORT$ TO EXTERNAL SORTMATGENEQEXIN/INTEXT/9/0/GSIZE $$ TRANSFORM MATRICES FROM INTERNAL SORT TO$ EXTERNAL SORT WITH APPROPRIATE DESIRED NAMESMPYADINTEXT,KAAGG,/KAAGGX/1 $MPYADKAAGGX,INTEXT,/KAAEXTSE $MODTRLKAAEXTSE////6 $MPYADINTEXT,PAG,/PAEXTSE/1 $MPYADINTEXT,GMNGG,/GMNGGX/1 $MPYADGMNGGX,INTEXT,/GMNEXTSE $$GENERATE DMIG FORMATMATMODKAAEXTSE,EQEXIN,,,,/MATPOOLK,/16/PUNCHFLGMATMODPAEXTSE,EQEXIN,,,,/MATPOOLP,/16/PUNCHFLGMATMODGMNEXTSE,EQEXIN,,,,/MATPOOLG,/16/PUNCHFLG$ MATPPOLK, MATPPOLP AND MATPOOLG OUTPUT DATA BLOCKS$ HAVE TO BE GENERATED ABOVE EVEN THOUGH ONLY DMIG$ PUNCHED OUTPUT IS DESIRED

MATMOD KAA,EQEXIN,USET,,,/,/16/PUNCHFLG/SORTFLG//////////

’KAAEXTSE’/’A’ $

MATMOD PA,EQEXIN,USET,,,/,/16/PUNCHFLG/SORTFLG//////////

’PAEXTSE’/’A’ $

MATMOD GMN,EQEXIN,USET,,,/,/16/PUNCHFLG/SORTFLG//////////

’GMNEXTSE’/’M’/’N’ $


Enhancements to External Superelement Usage Via EXTSEOUT Case Control Command

IntroductionThe EXTSEOUT Case Control command allows for the creation of an external superelement (SE) for subsequent use in an assembly process. Since its introduction in MSC.Nastran 2004, this feature has found widespread acceptance among a variety of superelement users. In response to many user needs and requirements, several enhancements have been introduced to this feature in MSC.Nastran 2005 r3. These enhancements are described below. Complete details are given in the expanded description of the EXTSEOUT command in the MSC.Nastran 2005 r3 Quick Reference Guide.

Addition of Options to ASMBULK KeywordIn pre-MSC.Nastran 2005 r3 versions, the ASMBULK keyword for the EXTSEOUT command has no options. Its use results in the generation of the following Bulk Data entries in the assembly punch (.asm) file:

SEBULK seid … (with MANUAL as the method for searching boundary points)SECONCT seid … (defines connections for boundary grid and scalar points)GRID entries for boundary grid pointsSPOINT entries for boundary scalar pointsCORD2x entries associated with the boundary GRID entries

The above entries are generated in order to avoid fatal errors that will be generated if there are coincident points associated with the boundary grid points in the assembly run. However, there are situations wherein there are no such coincident grid points in the assembly run. In such cases, there is no need to define or reference the boundary grid points in the .asm file and the SEBULK entry can have the default AUTO option. A new option, ASMBULK = AUTO, has therefore been introduced for this purpose. Under this usage, the current usage will be assumed to be equivalent to the default scenario of ASMBULK = MAN (for MANual).

Notice also that, in pre-MSC.Nastran 2005 r3 versions, the SECONCT entry mentioned above references only boundary grid and scalar points. Scalar Q-set points (representing generalized coordinates) are not referenced. There are, however, situations wherein a user may want to have explicit control on the Q-set DOFs of an external SE in the assembly run. In order to facilitate such a scenario, yet another option, ASMBULK = MANQ, has been introduced. This results in Q-set points being specified in SECONCT entries as well as on explicit SPOINT entries, thereby allowing them to be manipulated in the assembly run.


98

Thus, with the above usage, we have the following possible values for the ASMBULK keyword:

Addition of New FSCOUP KeywordA new keyword called FSCOUP has been added to control the storing of the boundary fluid-structure coupling matrix.

Addition of New DMIGSFIX KeywordIn pre-MSC.Nastran 2005 r3 versions, if the DMIGPCH option is employed, the DMIG Bulk Data entries for the boundary matrices that are generated in the standard punch (.pch) file are given the following names:

The above usage often causes confusion when the user is dealing with more than one external SE in an assembly run. In order to provide more flexibility and convenience to the user, a new keyword called DMIGSFIX (for DMIG suffix) has been added to the EXTSEOUT Case Control command. The format of this keyword is

DMIGSFIX = cccccc

where “cccccc” is a suffix (up to six characters) that will be appended to the appropriate letters to give unique names to the DMIG Bulk Data entries of the boundary matrices. Thus, with this usage, the DMIG Bulk Data entries for the boundary matrices will have the following names:

ASMBULK = MAN (default)

Simulates usage in pre-MSC.Nastran 2005 r3 versions

ASMBULK = MANQ

Similar to the usage in pre-MSC.Nastran 2005 r3 versions except that the SECONCT entry includes scalar Q-set points and SPOINT entries are generated for these scalar Q-set points

ASMBULK = AUTO

Generates a SEBULK entry (with AUTO as the assumed method for searching boundary points) along with an SECONCT entry with only boundary scalar points appearing on it and SPOINT entries for these boundary scalar points (if any)

KAAX (boundary stiffness matrix)

MAAX (boundary mass matrix)

BAAX (boundary viscous damping matrix)

K4AAX (boundary structural damping matrix)

PAX (boundary load matrix)

AAX (boundary fluid-structure coupling matrix)


If the name specified for DMIGSFIX is EXTID, it is regarded as a special case. In this case, the ID of the external SE specified via the EXTID keyword is used as part of the DMIG names. Thus, for example, if the user has specified EXTID = 15 and DMIGSFIX = EXTID, then the DMIG Bulk Data entries for the boundary matrices will have the following names:

The above design makes it very convenient for the user to associate the names of the boundary DMIG matrices with specific external SEs.

Automatic Numbering Scheme for Q-set DOFs Via AUTOQSET UsageWith the incorporation of the new AUTOQSET feature in MSC.Nastran 2005 r3, it is no longer necessary for the user to specify manual QSET / QSET1 and SPOINT entries to handle the Q-set DOFs (generalized coordinates) of an external SE. The program automatically generates SPOINT entries for these entities by using an internal numbering scheme that gives them IDs of the form 9sssnnnn where sss is the superelement ID specified by the EXTID keyword and nnnn is a mode number. Both sss and nnnn will have leading zeros inserted in them to ensure that sss is a three-digit number and nnnn is a four-digit

number. Thus, for example, the Q-set DOF corresponding to the 8th mode of external SE 5 would be represented by an SPOINT with an automatically generated ID of 90050008 while the Q-set DOF

corresponding to the 50th mode of external SE 25 would be represented by an SPOINT with an automatically generated ID of 90250050. The above numbering scheme offers great flexibility and convenience to the user, particularly when dealing with several external SEs in an assembly run.

Kcccccc (boundary stiffness matrix)

Mcccccc (boundary mass matrix)

Bcccccc (boundary viscous damping matrix)

K4cccccc (boundary structural damping matrix)

Pcccccc (boundary load matrix)

Acccccc (boundary fluid-structure coupling matrix)

K15 (boundary stiffness matrix)

M15 (boundary mass matrix)

B15 (boundary viscous damping matrix)

K415 (boundary structural damping matrix)

P15 (boundary load matrix)

A15 (boundary fluid-structure coupling matrix)


100

Automatic Availability of Output for Boundary Points and PLOTEL Points of External Superelements in Assembly RunThe output for an external superelement is generated in the assembly process. This output consists of displacements, velocities, accelerations, SPC forces and element stresses and forces. However, in order for this output to be generated in the assembly run, the output requests must be specified in the external superelement creation run. In pre-MSC.Nastran 2005 r3 versions, the only output requests for an external superelement that are honored in the assembly run are those that are specified in its creation run.

If there are many, many PLOTELs in an external SE creation run and the user is interested in utilizing them for animation in a subsequent assembly run, the above scheme forces the user to have explicit output requests for the grid points associated with the PLOTEL entries. This is an extremely cumbersome requirement. Similar comments also apply to boundary points of an external SE whose output the user may be interested in obtaining in the assembly run.

In order to avoid the above cumbersome and inconvenient requirement, the program has been enhanced to ensure that the output for the boundary grid and scalar points as well as for all grid points associated with PLOTEL entries for an external SE can be obtained in the assembly run even if there are no output requests specified for these points in the external SE creation run. This will be of tremendous convenience to users.

New MATDB Option As Equivalent to Current MATRIXDB OptionTo simplify user specification, a new option named MATDB has been introduced to be equivalent to the pre-MSC.Nastran 2005 r3 version MATRIXDB option. Both MATDB and MATRIXDB options are available and will be regarded as equivalent to each other, with the former being regarded as the new default option. This design will also ensure that legacy files will continue to run as before.


Changes to Rotordynamic for MSC.Nastran 2005 r3

Additional Damping Options for RotorsIn MSC.Nastran 2005 r3, additional rotor damping options were implemented. To support these enhancements, the RSPINR and RSPINT entries were modified. These modified entries are NOT compatible with previous versions of MSC.Nastran. Additionally, a new entry, HYBDAMP, was added to support ‘hybrid’ damping of rotors. For reference, the modified rotordynamic equations are given in Modified Basic Equations Used in Rotordynamics, 114.

RSPINR – Specifies the relative spin rates between rotors for complex eigenvalue, frequency response, and static analyses.

Format:

1 2 3 4 5 6 7 8 9 10

RSPINR ROTORID GRIDA GRIDB SPDUNIT SPTID

GR ALPHAR1 ALPHAR2 HYBRID

Field Contents

ROTORID Identification number of rotor. (Integer > 0; Required)

GRIDA/GRIDB Positive rotor spin direction is defined from GRIDA to GRIDB (Integer > 0; Required. See Remark 2.)

SPDUNIT Specifies whether the listing of relative spin rates is given in terms of RPM (revolutions/minute) or frequency (revolutions (cycles)/unit time). (Character; ’RPM’ or ’FREQ’; Required)

SPTID Relative spin rate. See Remark 3. (Real or Integer; if integer, must be > 0, Required)

GR Rotor structural damping factor. See Remark 3. (Real, Default = 0.0)

ALPHAR1 Scale factor applied to the rotor mass matrix for Rayleigh damping (Real, Default = 0.0. See Remark 5.)

ALPHAR2 Scale factor applied to the rotor stiffness matrix for Rayleigh damping (Real; Default = 0.0. See Remark 5.)

HYBRID Identification number of HYBDMP entry for hybrid damping (Integer > 0; Default = 0. See Remark 6.)


102

Remarks:1. An RSPINR entry must be present for each rotor defined by a ROTORG entry.

2. The rotor spin axis is determined from the ROTORG entries. The positive rotation vector is from GRIDA to GRIDB. GRIDA and GRIDB must be specified on the ROTORG entry.

3. If the entry is a real number, the value is considered constant. If the entry is an integer number, the value references a DDVAL entry that specifies the relative rotor spin rates. The number of spin rates for each rotor must be the same. Relative spin rates are determined by correlation of table entries. The ith entry for each rotor specifies the relative spin rates between rotors at RPMi/FREQi. Spin rates for the reference rotor must be in ascending or descending order.

4. Rotor structural damping specified by the GR entry will be added as equivalent viscous damping. The equivalent damping will be calculated using:

where is a user parameter

5. Rayleigh damping for the rotor will be calculated as

6. For hybrid damping of the rotors, only the rotor mass and stiffness will be used for the modes calculation.

Brotor[ ]s tructural

GRWR3------------ Krotor[ ]=

WR3

Brotor[ ]Rayleigh

αR1 Mrotor( ) αR2 Krotor[ ]+=


RSPINT– Specifies rotor spin rates for nonlinear and direct linear transient analysis.

Format:

Remarks:1. A RSPINT entry must be present for each rotor defined by a ROTORG entry.

2. The rotor spin axis is determined from the ROTORG entries. The positive rotation vector is from GRIDA to GRIDB. GRIDA and GRIDB must be specified on the ROTORG entry.

3. If the entry is a real number, the value is considered constant. If the entry is an integer number, the value references a TABLED1 entry that specifies the rotor spin rate history.

4. Rotor structural damping specified by the GR entry will be added as equivalent viscous damping. The equivalent damping will be calculated using:

1 2 3 4 5 6 7 8 9 10

RSPINT ROTORID GRIDA GRIDB SPDUNIT SPTID SPDOUT

GR ALPHAR1 ALPHAR2 HYBRID

Field Contents

ROTORID Identification number of rotor. (Integer > 0; Required)

GRIDA/GRIDB Positive rotor spin direction is defined from GRIDA to GRIDB.See Remark 2. (Integer > 0; Required.)

SPDUNIT Specifies whether the spin rates are given in terms of RPM (revolutions/minute) or frequency (revolutions(cycles)/unit time). (Character; ’RPM’ or ’FREQ’; Required)

SPTID Rrotor spin rate. See Remark 3. (Real or Integer; if integer, must be > 0, Required)

SPDOUT EPOINT to output the rotor speed vs. time. Output will be in SPDUNITs (Integer > 0 or blank)

GR Rotor structural damping factor. See Remark 3. (Real, Default = 0.0)

ALPHAR1 Scale factor applied to the rotor mass matrix for Rayleigh damping (Real,Default = 0.0. See Remark 5.)

ALPHAR2 Scale factor applied to the rotor stiffness matrix for Rayleigh damping. See Remark 5. (Real; Default = 0.0.)

HYBRI Identification number of HYBDMP entry for hybrid damping. See Remark 6. (Integer > 0, Default = 0)

Brotor[ ]s tructural

GRWR3------------ Krotor[ ]=


104

where WR3 is a user parameter.

5. Rayleigh damping for the rotor will be calculated as

6. For hybrid damping of the rotors, only the rotor mass and stiffness will be used for the modes calculation.

Brotor[ ]Rayleigh

αR1 Mrotor( ) αR2 Krotor[ ]+=


HYBDAMP– Hybrid modal damping for direct dynamic solutions.

Format:

Remarks:1. For KDAMP = “YES”, the viscous modal damping is entered into the complex stiffness matrix

as structural damping.

2. Hybrid damping is generated using modal damping specified by the user on TABDMP entries.

For KDAMP = “YES”

1 2 3 4 5 6 7 8 9 10

HYBDAMP ID METHOD SDAMP KDAMP

Field Contents

ID Identification number of HYBDMP entry (Integer > 0; Required)

METHOD Identification number of METHOD entry for modes calculation. (Integer > 0, Required)

SDAMP Identification number of SDAMP entry for modal damping specification. (Integer > 0; Required)

KDAMP Selects modal “structural” damping (Character: “Yes” or “NO”, see Remark 1; Default = “NO”)

BH φ1 φ2 … φn

b ω1( )

b ω2( )

b ωn( )

φ1T

φ2T

φnT

=

KH φ1 φ2 … φn

g ω1( )

g ω2( )

g ωn( )

φ1T

φ2T

φnT

=


106

where

Squeeze Film Damper as Nonlinear ForceThe squeeze film damper (SFD) was implemented as a nonlinear force similarly to the NLRGAP. The SFD forces are activated from the Case Control Section using the NONLINEAR command. The new NLRSFD Bulk Data entry has the following form:

Format:

= modes of the structure

= modal damping values,

= twice the critical damping ratio determined from user specified TABDMP entry

= natural frequency of mode

= generalized mass of mode

φi

b ωi( ) b ωi( ) g ωi( )ωimi=

g ωi( )

ωi φi

mi φi

1 2 3 4 5 6 7 8 9 10

NLRSFD SID GA GB PLANE BDIA BLEN BCLR SOLN

VISCO PVAPCO NPORT PRES1 THETA1 PRES2 THETA2 NPNT

OFFSET1 OFFSET2

Field Contents

SID Nonlinear load set identification number. (Integer > 0, Required)

GA Inner (e.g., damper journal) grid for squeeze film damper. (Integer > 0, Required)

GB Outer (e.g., housing) grid for squeeze film damper. (Integer > 0, Required)

PLANE Radial gap orientation plane: XY, XZ, or ZX. See Remark 1. (Character, Default = XY)

BDIA Inner journal diameter. (Real > 0.0, Required)

BLEN Damper length. (Real > 0.0, Required)

BCLR Damper radial clearance. (Real > 0.0, Required)

SOLN Solution option: LONG or SHORT bearing. (Character, Default = LONG)

VISCO Lubricant viscosity. (Real > 0.0, Required)

PVAPCO Lubricant vapor pressure. (Real, Required)

NPORT Number of lubrication ports: 1 or 2 (Integer, no Default)


Remarks:1. The XY, YZ, and ZX planes are relative to the displacement coordinates of GA and GB. The

plane coordinates correspond to the NLRSFD directions 1 and 2. GA and GB should be coincident grids with parallel displacement coordinate systems. Wrong answers will be produced if this rule is not followed.

2. The angular measurement is counterclockwise from the displacement x-axis for the XY plane, the y-axis for the YZ plane, and the z-axis for the ZX plane.

Squeeze Film Damper as Nonlinear ElementFor better accuracy and to facilitate use in other solution sequences the NLRSFD was also be implemented as an element. The Squeeze Film Damper was added as an option of a more general 2-D bearing element (CBUSH2D).

CBUSH2D

Format:

PRES1 Boundary pressure for port 1. (Real > 0.0, Required if NPORT = 1 or 2)

THETA1 Angular position for port 1. (0.0 < Real > 360.0, Required if NPORT = 1 or 2). See Remark 2.

PRES2 Boundary pressure for port 2. (Real > 0.0, Required if NPORT = 2).

THETA2 Angular position for port 2. See Remark 2. (0.0 < Real < 360.0, Required if NPORT = 2)

NPNT Number of finite difference points for damper arc. (Odd integer < 201, Default = 101)

OFFSET1 Offset in the SFD direction 1. (Real, Default = 0.0)

OFFSET2 Offset in the SFD direction 2. (Real, Default = 0.0)

Field Contents

1 2 3 4 5 6 7 8 9 10

CBUSH2D EID PID GA GB CID PLANE SPTID


108

PBUSH2D

Format:

Field Contents Default Values

EID Element identification number. (Integer > 0) Required

PID Property identification number of a PBUSH2D entry. (Integer > 0).

Required

GA Inner grid. (Integer > 0) Required

GB Outer grid. (Integer > 0) Required

CID Coordinate system used to define 2-D plane. (Integer > 0) 0

PLANE Orientation plane in CID, XY, YZ, ZX (Character) “XY”

SPTID Optional rotor speed input for use with table lookup or DEQTN generation of element properties (Integer > 0 or blank)

1 2 3 4 5 6 7 8 9 10

PBUSH2D PID K11 K22 B11 B22 M11 M22

“SQUEEZE” BDIA BLEN BCLR SOLN VISCO PVAPCO

NPORT PRES1 THETA1 PRES2 THETA2 OFFSET1 OFFSET2

Field Contents Default

PID Property identification number. (Integer > 0). Required

K11 Nominal stiffness in T1 rectangular direction. (Real) Required

K22 Nominal stiffness in T2 rectangular direction. (Real) Required

B11 Nominal damping in T1 rectangular direction. (Real) Default = 0.0

B22 Nominal damping in T2 rectangular direction. (Real) Default = 0.0

M11 Nominal acceleration-dependent force in T1 direction. (Real) Default = 0.0

M22 Nominal acceleration-dependent force in T2 direction. (Real) Default = 0.0

“SQUEEZE” Indicates that squeeze-film damper will be specified. (Character) Required

BDIA Inner journal diameter (Real > 0.0) Required


Gyroscopic Terms Added to Aero Solution SequencesThe rotordynamics option is available in the Aerodynamic Flutter (SOL 145) and Aeroelastic Gust Response (SOL 146) solutions. SOL 145 uses the same gyroscopic equations as Complex Eigenvalues; SOL 146 uses the frequency response formulation (see Modified Basic Equations Used in Rotordynamics, 114).

Campbell DiagramsCampbell diagram generation is activated in complex modes analysis (SOLs 107 and 110) by the CAMPBELL Case Control command. The command will have the following format:

CAMPBELL= n

The CAMPBELL command references the following Bulk Data entry.

Format:

BLEN Damper length (Real > 0.0) Required

BCLR Damper radial clearance. (Real > 0.0) Required

SOLN Solution option: LONG or SHORT bearing (Character) Default = LONG

VISCO Lubricant viscosity. (Real > 0.0) Required

PVAPCO Lubricant vapor pressure. (Real) Required

NPORT Number of lubrication ports: 1 or 2 (Integer) No Default

PRES1 Boundary pressure for port 1 (Real > 0.0) Required if NPORT = 1 or 2

THETA1 Angular position for port 1. See Remark 2. (0.0 < Real <360.0) Required if NPORT = 1 or 2

PRES2 Boundary pressure for port 2 (Real > 0.0) Required if NPORT = 2

THETA2 Angular position for port 2. See Remark 2. (0.0 < Real < 360.0) Required if NPORT = 2

OFFSET1 Offset in the SFD direction 1 (Real) Default = 0.0

OFFSET2 Offset in the SFD direction 2 (Real) Default = 0.0

Field Contents Default

1 2 3 4 5 6 7 8 9 10

CAMPBLL CID VPARM DDVALID TYPE ID NAME/FID


110

Rotor Forward and Backward Mode IdentificationForward and backward rotor modes are identified using proportional kinetic and strain energies of the reference rotor compared to the total structure. The motion of the reference rotor is split into forward and backward components using a least-mean-square fit of shape vectors that represent ‘pure’ forward and backward rotor whirl motion. The ‘pure’ forward and backward components are then used to calculate the kinetic and strain energies of the reference rotor.

‘Pure’ forward and backward whirl modes represent unit circular motion. For example, with rotation along the positive z-axis, ‘pure’ whirl for translation or rotation are given by:

(5-1)

Field Contents

CID Identification number of entry (integer > 0, required).

VPARM Variable parameter, allowable entries are: ‘SPEED’, ‘PROP’, ‘MAT’.

‘SPEED’, reference rotor speed will be varied (rotordynamic option only).

‘PROP’, element property values will be varied (currently not implemented)

‘MAT’, element material properties will be varied (currently not implemented).

DDVALID Identification number of DDVAL entry that specifies the values for the variable parameter (integer > 0, required).

TYPE For VPARM set to ‘SPEED’ allowable entries are: ‘FREQ’ and ‘RPM’.

For VPARM set to ‘PROP’, allowable entries are the names of property entries, such as ‘PBAR’, ‘PELAS’, etc.

For VPARM set to ‘MAT’, allowable entries are the names of material entries, such as ‘MAT1’ or ‘MAT2’, etc.

ID Property or material entry identification number (integer > 0, not required for VPARM set to ‘SPEED’, required for VPARM set to ‘PROP’ or ‘MAT’).

NAME/FID For VPARM set to ‘SPEED’, no entry required.For VPARM set to ‘PROP’, property name, such as ‘T’, ‘A’, or field position of the property entry, or word position in the element property table of the analysis model. For VPARM set to ‘MAT’, material property name, such as ‘E’ or ‘RHO’, or field position of the material entry.

φ forward

1

i–

0

= φ backward

1

i

0

=


The forward and backward components are found by minimizing the error between the calculated modes and the ‘pure’ forward and backward whirl vectors of the reference rotor.

(5-2)

where: is the calculated mode are the forward and backward ‘pure’ whirl modes for all rotor grid translations

and rotations. are the whirl mode scale factors

(5-3)

(5-4)

(5-5)

(5-6)

The error is minimized using a least-mean-square procedure. The square of the error is

(5-7)

The derivative of the above equation with respect to is

err φ = A[ ] α –

φ A[ ]

α

A[ ] A[ ] forward A[ ] backward[ ]=

A[ ] forward

φ forward

0

0

.

.

.

0

φ forward

0

.

.

.

0

0

.

.

.

φ forward

=

A[ ] backward

φ backward

0

0

.

.

.

0

φ backward

0

.

.

.

0

0

.

.

.

φ backward

=

α α forward

αbackward

=

err 2err

* T

err φ * A*[ ] α * –( )

Tφ A[ ] α –( )T

= =

φ* T

φ φ * T

A[ ] α – α* T

A*[ ]

Tφ – α*

TA

*[ ]T

A[ ] α +=

α


112

(5-8)

Setting the above equation to zero and taking the complex transpose results in

(5-9)

Solving for produces

(5-10)

Using Eq. (5-1) and Eq. (5-3), the following simplification can be made,

(5-11)

The terms are used to calculate the forward and backward components of the modes,

(5-12)

The proportional rotor kinetic and strain energies are determined using the following procedure:

(5-13)

(5-14)

where:

(5-15)

(5-16)

and the norm of the vector is defined as the sum of the absolute values of all the terms.

Note that scale factors in the above equations have been removed because the proportional calculation will cancel these terms.

Modes with kinetic or strain energies greater than a user specified value will be considered forward or backward whirl modes.

∂err2

∂α-------------- φ* A[ ]– α*

TA

*[ ]T

A[ ]+=

A*[ ]

Tφ – A

*[ ]T

A[ ] α + 0 =

α

α A*[ ]

TA[ ]( )

1–A

*[ ]T

φ =

α 12--- A

*[ ]T

φ =

α

φrotor forward

12--- A[ ] forward A

*[ ] forwardT

φ ( )=

φrotor backward

12--- A[ ] backward A

*[ ] backwardT

φ ( )=

Proportional Kinetic Energynorm KE φrotor( )

norm KE φ( )-----------------------------------------------=

Proportional Strain Energynorm SE φrotor( )

norm SE φ( )----------------------------------------------=

KE u( ) M[ ] u ( ) u ⋅=

SE u( ) K[ ] u ( ) u ⋅=


Rotor Mode TrackingFor Campbell diagram plotting, the rotor modes will need to be tracked in case the eigenvalues of the modes change ordering. Forward and backward modes should be separated using the previous procedure and tracked separately. Tracking can be done using a method similar to the previous procedure to determine forward and backward modes. Defining an error function as

(5-17)

where: is a weighting matrix (usually , , or )

are the normalized forward and backward whirl modes (rotor dofs only)

are the scaling factors to fit the modes

the subcase increment number

The modes are normalized by the following method.

(5-18)

Using the same method in the above procedure produces the following results for the scaling matrix

. (5-19)

The matrix is used to whether the modes have shifted position in the LAMA table.

The matrix columns are examined for the largest term. This term is set to 1.0 and the other terms

in the column are set to 0.0. The matrix can now be used to shuffle the eigenvalues.

(5-20)

The new order is appended to the LAMA matrix for Campbell Diagram plotting.

(5-21)

CommentsFor speed-dependent Campbell diagrams, at low speeds, the split into forward and backward modes may not be very pronounced. It may be best to start at the higher speeds and move down instead of moving up. Also, do not try to find forward and backward modes at zero RPM.

When forward and backward modes cross, they may be difficult to separate. If this happens, it is probably best to ‘jump’ (ignore) these modes and continue to the next rotor speed. They should be picked-up at the next speed step. We will need to ‘fill-in’ later so PATRAN can plot the results.

err[ ] X[ ] φ[ ] i 1–= X[ ] φ[ ] i β[ ]–

X[ ] M[ ] K[ ] I[ ]

φ[ ]

β[ ]

i

φ φ

φ* T

X*[ ]

TX[ ] φ

--------------------------------------------------=

β[ ] φ*[ ] iT

X*[ ]

TX[ ] φ[ ] i( )

Tφ*[ ] i

TX

*[ ]T

X[ ] φ[ ] i 1–( )=

β[ ]

β[ ]β[ ]

LAMA new LAMA old β[ ]=

LAMA[ ] LAMA 1 LAMA 2 LAMA 3…[ ]=


114

Modified Basic Equations Used in RotordynamicsThe NASTRAN time-domain equation solved by the new dynamic solution sequences is:

(5-22)

= total mass matrix

= support viscous damping matrix

= support mass contribution for Rayleigh damping

= support stiffness contribution for Rayleigh damping

= support viscous damping equivalent to structural damping

= support viscous damping equivalent to material structural damping

= rotor viscous damping matrix

= rotor hybrid damping matrix

= rotor mass contribution for Rayleigh damping

= rotor stiffness contribution for Rayleigh damping

= rotor viscous damping equivalent to structural damping

= rotor viscous damping equivalent to material structural damping

= rotor viscous damping equivalent to hybrid structural damping

= gyroscopic force matrix

= support stiffness matrix

= rotor stiffness matrix

= support material damping matrix

= rotor material damping matrix

Mu·· t( )Bs α 1Ms α 2Ks+ +( ) g

W3-------- Ks

1W4-------- K4s+ +

BR BHR α 1RMR α 2RKR+ + +( )gR

WR3------------ KR

1WR4------------ K4R

1WRH-------------- KHR ΩB

G+ + + + +

u· t( )+

Ks Kr+

Ω KCB

KCBH α 1RK

CM α 2RKCK gr

WR3------------ K

CK 1WR4------------ K

CK4 1WRH-------------- K

CKH+ + + + + + +

u t( )+ F t( )=

M

Bs

α 1Ms

α 2Ks

gW3-------- Ks

1W4-------- K4s

Br

BH

α 1RMR

α 2RKRgr

WR3------------ KR

1WR4------------ K4R

1WRH-------------- KHR

BG

Ks

KR

K4s

K4R


The NASTRAN frequency-domain equation is:

(5-23)

In the special situation where , the above equation is converted to

(5-24)

Eq. (5-23), asynchronous excitation, and Eq. (5-24), synchronous excitation, are used in frequency response and complex modes analyses.

To order to support multiple rotors spinning at different rates, Eqs. (5-23) and (5-24) are modified to the following forms:

Frequency ResponseFor frequency response with asynchronous excitation, for each rotor is constant and can be determined from the rotation speed of the reference rotor, , and relative rotation rates specified by

the user. The equation of motion to be solved is:

= rotor rotation rate

= “circulation” matrix due to

“circulation” matrix due to




, , and are users parameters

Ω

KCB

BR

KCBH

BHR

gRKRCK gRKR

KRCK4

K4R

KCKH

KHR

WR3 WR4 WRH

ω2M–( iω Bs α 1Ms α 2Ks B+ +

rBHR α 1RMR α 2RKR Ω+ + + B

G+ +( )+

1 ig+( )KS iK4S 1 igR+( )KR iK4R iKHR+ + + +

Ω KCB

KCBH α 1RK

CM α2RKCK gR

ω------ K

CK 1ω---- K

CK4 1ω---- K

CKH+ + + + + +

+

+ u ω( ) F ω( )=

ω Ω=

Ω2M iB

G–( )– iΩ

BS α1MS α2KS BR BHR α1RMR α 2RKR+ + + + + +

i KCB

KCBH α 1RK

CM α2RKCK

+ + +( )–

+

1 ig+( )KS iK4S+

1 igR+( )KR iK4R iKHR gRKCK

KCK4

KCKH

+ + + + + +

u Ω( ) F Ω( )=+

ΩΩref


116

(5-25)

where the subscript j references the individual rotors.

will be determined for each excitation frequency, similar to frequency-dependent elements.

For the option to bypass the frequency-dependent looping, the equation of motion to be solved is:

(5-26)


For frequency response with synchronous excitation, the excitation frequency is equal to the spin rat of the reference rotor, . The spin rates of the additional rotors can be determined from the

relative spin rates specified by the user. The equation of motion to be solved is:

(5-27)


will be determined for each excitation frequency, similar to frequency-dependent elements.

ω2M– iω

BS α 1MS α 2KS+ +

BRj

j 1=

n

∑ BHRj α 1RjMRj α 2RjKRj Ωj Ωre f( )BjG

+ + + + +

+

1 ig+( )KS iK4S+

1 igRj+( )KRj iK4Rj iKHRj+ +

Ωj Ωref( ) KjCB

KjCBH α 1RjKj

CM α 2RjKjCK gRj

ω------- Kj

CK 1ω---- Kj

CK4 1ω---- Kj

CKH+ + + + + + +

j 1=

n

∑+

u ω( ) F ω( )=+

1 ω⁄( )

ω2M– iω

BS α 1MS α 2KS + + +

BRj BHRj α 1RjMRj α 2RjKRj Ωj Ωref( )BjG gRj

WR3------------ KRj

1WR4------------ K4Rj

1WRH-------------- KHRj+ + + + + + +

j 1=

n

∑

+

1 ig+( )KS iK4S+

KRj Ωj Ωref( )( )+

j 1=

n

∑+

+

KjCB

KjCBH α 1RjK

CM α 2RjKCK gRj------------

KjCK 1------------

KjCK4 1--------------

KRjCKH+ + + + + +

u ω( ) F ω( )=

ω Ωref=

Ωref2

M iΩref

BS α 1MS α2KS+ +

BRj

j 1=

n

∑ BHRj α 1RjMRj α 2RjKRj Ωj Ωre f( )BjG

+ + + + +

+–

1 ig+( )KS iK4S+

1 igj+( )KRj iK4Rj iKHRj+ +

ΩjΩre f+

j 1=

n

∑+

KjCB

KjCBH α 1RjKj

CM α 2RjKjCK gRj

Ωre f------------

KjCK 1

Ωref---------- Kj

CK4 1Ωref---------- Kj

CKH+ + + + + +

u Ωref( ) F Ωref( )=

+

Ωj Ωref( )


For the option to bypass the frequency-dependent lookup of rotor speeds, for each rotor is written as a linear function dependent on the reference rotor spin rate . The scaling factors,

and , are determined from the relative spin rates specified by the user. The in the terms

are replaced by the values of user parameters WR3, WR4, and WRH. The equation of motion to be solved is:

(5-28)


Complex ModesFor complex modes with asynchronous excitation, the spin rate for each rotor is constant and can be determined from user input and the reference rotor spin rate, . The equation of motion to be

solved is:

ΩΩj Ωref( ) α j βjΩre f+=( )

α j βj Ωref 1 Ωre f⁄

Ωref2

M i βjBjG

j 1=

n

∑–

–

iΩre f BS α 1MS α 2KS

j 1=

n

∑+ + +

+

BRj BHRj α 1RjMRj α 2RjKRj α jBjG gRj

WR3------------ KRj

1WR4------------ K4Rj

1WRH-------------- KHRj+ + + + + + +

iβj KjCB

KjCBH α 1RjKj

CM α 2RjKjCK gRj

WR3------------ Kj

CK 1WR4------------ Kj

CK4 1WRH-------------- Kj

CKH+ + + + + +

–

1 ig+( )KS iK4S + +

KRj α j+

j 1=

n

∑

+

KjCB

KjCBH α 1RjKj

CM α 2RjKjCK gRj

WR3------------ Kj

CK 1WR4------------ Kj

CK4 1WRH-------------- Kj

CKH+ + + + + +

u Ωref( ) F Ωref( )=

ΩΩref


118

(5-29)


For complex modes analysis with synchronous excitation, the excitation frequency is equal to the spin rat of the reference rotor, . for each rotor is written as a linear function dependent on the

reference rotor spin rate . The scaling factors, and , are determined from the

relative spin rates specified by the user. The equation of motion to be solved is:

(5-30)


ω2M– iω

BS α 1MS α 2KS + + +

j 1=

n

∑

+

BRj BHRj α 1RjMRj α 2RjKRj Ωj Ωre f( )BjG gRj

WR3------------ KRj

1WR4------------ K4Rj

1WRH-------------- KHRj+ + + + + + +

1 ig+ KS iK4S + +

j 1=

n

∑+

+

KRj Ωj Ωref( ) KjCB

KjCBH α 1RjK

CM α 2RjKCK gRj

WR3------------ Kj

CK 1WR4------------ Kj

CK4 1WRH-------------- Kj

CKH+ + + + + + +

u ω( ) 0=

ω Ωref= ΩΩi Ωref( ) α j βjΩre f+=( ) α j βj

Ωref2

M i βjBjG

j 1=

n

∑––

iΩref BS α 1MS α 2KS

j 1=

n

∑+ + +

+

BRj BHRj α 1RjMRj α 2RjKRj α jBjG gRj

WR3------------ KRj

1WR4------------ K4Rj

1WRH-------------- KHRj+ + + + + + +

iβjKjCB

KjCBH α 1RjKj

CM α2RjKjCK gRj

WR3------------ Kj

CK 1WR4------------ Kj

CK4 1WRH-------------- Kj

CKH+ + + + + +–

1 ig+( )KS iK4S + +

KRj α j+

j 1=

n

∑

+

KjCB

KjCBH α+ 1RjKj

CM α 2RjKjCK gRj

WR3------------ Kj

CK 1WR4------------ Kj

CK4 1WRH-------------- Kj

CKH+ + + + +

u Ωref( ) 0=


Nonlinear Transient ResponseFor nonlinear transient response, is time dependent, the equation of motion to be solved is:

(5-31)

Ω

Mu·· t( )

Bs BRj α+ 1Ms α 2Ks+ +g

W3-------- Ks

1W4-------- K4s+ +

BRj BHRj α 1RjMRj α 2RjKRj+ + +

j 1=

n

∑gR

WR3------------ KR

1WR4------------ K4Rj

1WRH-------------- KHRj Ωj t( )Bj

G+ + + + +

u· t( )+

KS

j 1=

n

∑+ KRj Ω

·j t( )Kj

T+

Ωj t( ) KjCB

KjCBH α 1RjKj

CM α 2RjKjCK gr

WR3------------ Kj

CK 1WR4------------ Kj

CK4 1WRH-------------- Kj

CKH+ + + + + +

+

+

u t( ) F t( )=


120


Ch. :

6 Aeroelasticity

! Monitor Points, 122

! Spline6/7, 129

! Combination of Controllers/User Input Loads Enhancements, 131

! Separate Rigid and Flexible Aero Meshes, 133

! Miscellaneous Aeroelastic Enhancements, 135


122

Monitor Points

Introduction“Monitor Points” is a term used collectively to refer to four data items that have been implemented in MSC.Nastran:

1. MONPNT1 – The MONPNT1 provides integrated loads at a user defined point in a user defined coordinate system. The user also identifies the nodes (on either the structural or aerodynamic model) whose loads are to be integrated. This feature has been available since the 2001 release of MSC.Nastran. MSC.Nastran 2005 r3 adds the ability to specify an output coordinate system in addition to the coordinate system used in defining the location of the integration point. It availability has been extended from SOL 144 to SOL’s 101 and 1467.

2. MONPNT2 – The MONPNT2 provides element results (Stress, Strain, Force) in a tabulated fashion. For the results to be accurate, the term selected must be a linear function of the displacements.

3. MONPNT3 – The MONPNT3 provides a summation of grid point forces at a user specified integration points. This can be used to provide the net load acting at a fuselage or wing station by making a “cut” in the structure and then identifying all the grids and elements on one side of the cut

4. MONDSP1 – The MONDSP1 allows for the sampling of a displacement vector to create a blended displacement response at a user specified point and coordinate system. The displacement monitor point is essentially an RBE3 element (limited to a single dependent point) and the dependent grid is now an arbitrary point.

While Monitor Points have been developed with primarily aeroelastic considerations in mind, their applicability in any type of analysis is recognized. The following table shows which solution sequences currently support monitor point processing.

Special Considerations for the MONPNT3

The original implementation of the MONPNT3 relied on the GPFDR (grid point force data recovery) module to compute the grid point forces and two new modules to post-process this information to obtain the point information. This proved to have significant performance problems so that an alternative was developed. The enhanced process identifies the elements that participate in the calculation of the monitor point result and then does a mini EMA (element matrix assembly) to form a stiffness matrix that just includes those elements. Multiplying this matrix by an integration matrix that transfers forces to the

Solution Sequence MONPNT1 MONPNT2 MONPNT3 MONDSP1

SOL 101 X x x x

SOL 144 X x x x

SOL 146 X x

123CHAPTER 6Aeroelasticity

monitor point results in a matrix S that can be multiplied by the set of solution vectors U to provide the monitor point results:

(6-1)

The S matrix (denoted MP3INT in the dmap sequences) is computed as a preprocessing operation. The monitor point results are then calculated using Equation (6-1) or 2 once the displacements have been computed.

In this enhanced process, the exclusion flag (XFLAG) has special significance. This flag can be used to exclude specified force types from the calculation. If the XFLAG field is set by the user to exclude all of the candidate force types (i.e., XFLAG=SMAD), then the enhanced algorithm can be employed and a filtering process is applied to see which set of the elements and grids listed in the GRIDSET and ELEMSET will result in a non-zero resultant force. I.e., if all the elements attached to a particular grid are included in the ELEMSET, the grid can be filtered out and if all the grids a particular element attaches to are included in the GRIDSET, then the element can be filtered out. The remaining grids and elements are then included in the mini-EMA step.

If the XFLAG is blank, then a complementary filtering process occurs. Excluding of grids and elements occurs as above but now the remaining set of elements is discarded and the mini-EMA includes those elements that are attached to the retained grids that are NOT included in the ELEMSET.

If some, but not all, of the candidate force type are excluded (e.g., XFLAG=A), then the enhanced method cannot be applied and the MONPNT3 processing reverts to the original grid point force methodology.

BenefitsThe MONPNT1 is discussed in some detail in Chapter 5 of the MSC.Nastran 2001 Release Guide. Briefly, it provides the user with a way to extract the applied loading for a specified set of structural nodes or aerodynamic elements. This enables the batch calculation of VMT (shear, moment and torque) data as well at aerodynamic coefficient data for user specified regions and locations.

The MONPNT2 provides a way of pinpointing a particular response for output, as opposed to finding a particular item in a large OFP listing.

The MONPNT3 provides a summation of the internal loads and therefore useful in calculating resultant forces at a cut in the structure.

The MONDSP1’s ability to provide an averaged displacement is seen as providing a qualitative assessment of the elastic deflection of a vehicle. An example is to monitor the nominal pitch and plunge at a station along the wing.

InputThe MONITOR Case Control command provides control over the print of the monitor points results Toggles can be used to control the print of the individual monitor types. This command must be placed

MP3 ST

U=


124

above the subcase level or in the first subcase and applies to all subcases. The print associated with SOL 146 results can be particularly voluminous since data can be given for every frequency or time point.

The MONPNT1, MONPNT2, MONPNT3 and MONDSP1 entries are shown in the Quick Reference Guide. As mentioned, the MONPNT1 has been enhanced to provide an output coordinate system for displaying the results. Note that the loads can be on the structural or the aerodynamic model as specified by the COMP field that, in turn, identifies a AECOMP entry that can invoke CAEROi or AELIST entries for aerodynamic elements or a SET1 entry for structural grids.

The MONPNT2 entry requests that the user identify the element type and NDDL item. The type is obtained from the table given in Remark 5 of this entry and it is seen that there are separate types for composite and element corner results.

The MONPNT3 entry identifies a piece of structure by identifying the elements and nodes associated with it. The grid point force data associated with these entities is then integrated to the location specified on the entry. The XFLAG can be used to exclude certain grid point force types from consideration.

The MONDSP1 entry is similar to the MONPNT1 entry but now it is displacements that are being averaged. The AECOMP entry can invoke either structural grids or aerodynamic elements.

Output A comprehensive depiction of the prints of the monitor points across all the solution sequences would be too detailed for the purposes of this document. Several key tables are presented here and it is suggested that the examples of the following subsection be exercised to get an idea of the printout to expect. For SOL 144, the MONPNT1 and MONDSP1 entries can be on either the aerodynamic or the structural mesh. An example of MONPNT1 output on both meshes that is extracted from the m31chk example file is shown here:


It is seen that the trim state is first printed and this is followed by labeling information and finally the data. The monitor points extend over the same portion of the vehicle and it is seen that the results compare well. In this case, there is no externally applied load so that the structural results show zeroes and there are no applied loads on the aero mesh. If applied structural loads were present, the rigid and elastic total loads would be printed in the two columns while only the elastic increment would be printed for the aerodynamic model.

A print of MONDSP1 data extracted from the msimpms example is shown next.

S T R U C T U R A L M O N I T O R P O I N T I N T E G R A T E D L O A D S CONFIGURATION = AEROSG2D XY-SYMMETRY = ASYMMETRIC XZ-SYMMETRY = ASYMMETRIC MACH = 5.000000E-01 Q = 7.000000E+02

CONTROLLER STATE: ANGLEA = 9.6005E-03 URDD3 = -1.0000E+00 ELEV = 1.7303E-01

MONITOR POINT NAME = CANARD COMPONENT = CANARDS CLASS = GENERAL LABEL = THE CANARD STRUCTURAL POINTS CP = 900 X = 5.00000E+00 Y = 2.00000E+00 Z = 0.00000E+00 CD = 900

AXIS RIGID AIR ELASTIC REST. INERTIAL RIGID APPLIED REST. APPLIED ---- ------------- ------------- ------------- ------------- ------------- CX 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 CY 0.000000E+00 0.000000E+00 5.530298E-14 0.000000E+00 0.000000E+00 CZ 4.735976E+03 4.835128E+03 5.000000E+01 0.000000E+00 0.000000E+00 CMX 7.039471E+03 7.187045E+03 6.000000E+01 0.000000E+00 0.000000E+00 CMY 1.717664E+04 1.727710E+04 0.000000E+00 0.000000E+00 0.000000E+00 CMZ 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

A E R O D Y N A M I C M O N I T O R P O I N T I N T E G R A T E D L O A D S CONFIGURATION = AEROSG2D XY-SYMMETRY = ASYMMETRIC XZ-SYMMETRY = ASYMMETRIC MACH = 5.000000E-01 Q = 7.000000E+02

CONTROLLER STATE: ANGLEA = 9.6005E-03 URDD3 = -1.0000E+00 ELEV = 1.7303E-01

MONITOR POINT NAME = CANARD COMPONENT = CANARDA CLASS = GENERAL LABEL = THE CANARD AERO PANEL CP = 900 X = 5.00000E+00 Y = 2.00000E+00 Z = 0.00000E+00 CD = 900

AXIS RIGID AIR ELASTIC REST. ---- ------------- ------------- CX 0.000000E+00 0.000000E+00 CY 0.000000E+00 0.000000E+00 CZ 4.735976E+03 4.835128E+03 CMX 7.039471E+03 7.187045E+03 CMY 1.717664E+04 1.727710E+04 CMZ 0.000000E+00 0.000000E+00


126

In this case, different displacement requests have been made so that the structural and the aerodynamic results do not compare.

The final output shown here is for MONPNT2 and MONPNT3 results from a SOL 101 run made with example q2010601.

S T R U C T U R A L M O N I T O R P O I N T D I S P L A C E M E N T S CONFIGURATION = AEROSG2D XY-SYMMETRY = ASYMMETRIC XZ-SYMMETRY = SYMMETRIC MACH = 4.500000E-01 Q = 2.000000E+00

CONTROLLER STATE: URDD3 = 1.4909E-04 URDD5 = -2.5493E-05

MONITOR POINT NAME = SWTIP COMPONENT = SWTIP CLASS = DISPLACEMENT LABEL = TRANSVERSE DISP AND TWIST AT WING TIP CP = 0 X = 2.51500E+00 Y = 5.52500E+00 Z = 0.00000E+00 CD = 0

AXIS ELASTIC REST. ---- ------------- TZ 2.835612E+00 RY -2.929023E-02

A E R O D Y N A M I C M O N I T O R P O I N T D I S P L A C E M E N T S CONFIGURATION = AEROSG2D XY-SYMMETRY = ASYMMETRIC XZ-SYMMETRY = SYMMETRIC MACH = 4.500000E-01 Q = 2.000000E+00

CONTROLLER STATE: URDD3 = 1.4909E-04 URDD5 = -2.5493E-05

MONITOR POINT NAME = AWTIP COMPONENT = ACAERO CLASS = DISPLACEMENT LABEL = PITCH AND PLUNGE AT THE WING TIP CP = 0 X = 2.30000E+00 Y = 4.70000E+00 Z = 0.00000E+00 CD = 0

AXIS ELASTIC REST. ---- ------------- TX 0.000000E+00 TY 0.000000E+00 TZ 2.207074E+00 RX 5.431858E-01 RY -3.140820E-02 RZ 0.000000E+00


It is seen that each MONPNT2 produces its own line of data for each subcase while the MONPNT3 results contain as many rows as the have been specified in the AXES field on the MONPNT3 entry.

ExamplesThe monitor point capability extends across solutions sequences and monitor point types. The following table contains the names of tpl files that demonstrate a particular combination.

Guidelines and LimitationsThe MONITOR Case Control command is required to obtain monitor point output in SOL’s 101 and 146. For SOL 144, the case control is not required for the MONPNT1 and MONDSP1 prints, but is needed for MONPNT2 and MONPNT3.

S T R U C T U R A L I N T E R N A L M O N I T O R P O I N T L O A D S (MONPNT2)

MONITOR POINT NAME = MONPNT2

VALUE EID ETYPE CLASS RESPONSE LABEL SUBCASE NO. ------------- ---------- -------- -------- -------- ---------------------------------------------------------------------- 1.504374E+00 1100081 QUAD4 STRESS SY1 MPT21 THIS IS A STRESS-MONPT2 MONITOR POINT 1

MONITOR POINT NAME = MONPNT2

VALUE EID ETYPE CLASS RESPONSE LABEL SUBCASE NO. ------------- ---------- -------- -------- -------- ---------------------------------------------------------------------- 3.008748E+00 1100081 QUAD4 STRESS SY1 MPT21 THIS IS A STRESS-MONPT2 MONITOR POINT 2

S T R U C T U R A L F R E E B O D Y M O N I T O R P O I N T I N T E G R A T E D L O A D S

MONITOR POINT NAME = MPT31 COMPONENT = 5 CLASS = GENERAL SUBCASE NO. 1 LABEL = THIS IS A FREE BODY MONITOR POINT ICID = 52 X = 1.00000E+00 Y = 2.00000E+00 Z = 3.00000E+00

AXIS REST. APPLIED ---- ------------- CX 2.433662E-01 CY 1.720859E-01 CZ 0.000000E+00 CMX -2.460616E+00 CMY 3.479837E+00 CMZ -1.559533E+00

SOLution 101 144 144 146(time) 146(time) 146(freq) 146(freq)

Type Structure Structure Aero Struct Aero Structure Aero

Monitor

MONDSP1 Q2010601 msimpms msimpms fmondsp fmondsp Gustfff Gustfff

MONPNT1 Q2010601 freedlm freedlm fmondsp fmondsp Gustfff gustfff

MONPNT2 Q2010601 M31chk n/a n/a n/a n/a n/a

MONPNT3 Q2010601 M31chk n/a n/a n/a n/a n/a


128

The prints in SOL 146 can be voluminous since each component that is printed requires its own table for the list of frequency or time points.

For the aeroelastic solutions, the MONPNT1 and MONDSP1 data can be calculated based on structural grids or aerodynamic elements. MONPNT2 and MONPNT3 results are only available on the structural model.

The MONPNT2 results are computed by multiplying a predefined matrix times the solution vector. This assumes that the desired quantity is a linear function of the solutions. Clearly, this is not the case for synthesized responses; e.g. (von Mises stress).


Spline6/7

Introduction Two new spline method are available in MSC.Nastran 2005 r3: 3D finite surface spline (SPLINE6) and 3D finite beam spline (SPLINE7). These splines support 6 degrees of freedom for both the aerodynamic and structural meshes and may be used to couple the aerodynamic and structural models.

Both methods use the same basic approach to solving the interpolation problem: they form a small, virtual finite element enforced motion statics problem to measure the motion of the dependent dofs. The computed displacements under unit enforced motion of the independent grids are then the spline interpolant. In the case of the beam spline (as shown in Figure 6-1 below), the virtual mesh is comprised of a set of bar elements laid along a user-defined axis. The independent and dependent points are connected to the virtual beam by RBE3 and RBE2 elements. In the case of the plate spline, the user defines the mesh and RBE3 elements are used to connect the DOF’s to the virtual surface mesh. The user can specify the elements that are to be used in the virtual mesh. Typically, the aerodynamic elements are used as the virtual mesh.

Figure 6-1


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Benefits These new methods work across almost all aero mesh types and are suitable for “external” aero methods in addition to structure-to-structure splines. These new methods are the only ones that are full 6DOF to 6DOF spline methods; hence, they are the only ones that can be used in structure-to-structure loads mapping applications. With a little work using standard Nastran or by using the MSC.Nastran toolkit, these two new spline methods may be used to perform structure-to-structure splining.

Standard MSC.Nastran does not support the user interface to drive the methods for structure-to-structure mapping so it would be necessary to develop custom mapping tools, perhaps using MSC.Nastran Toolkit to drive the mapping of loads from the aeroelastic finite element model to the internal loads FE using these methods.

InputThe SPLINE6 and SPLINE7 entries are described in some detail in the MSC.Nastran Quick Reference Guide. These entries do not result in additional output.


Combination of Controllers/User Input Loads Enhancements

IntroductionChanges were made in the user interface for aeroelasticity to facilitate synthesizing controllers from multiple inputs. The first change was a simple change in AELINK Bulk Data entry that is of significant benefit when many subcases are being run. The AELINK entry now supports the character string “ALWAYS” or ID=0 in place of the trim set ID specified at the subcase level in case control. The effect of this is that a single AELINK entry can now apply to all of the subcases in the run.

The AEFORCE Bulk Data entry was enhanced in several ways: the resulting description of AEFORCE Bulk Data entry in Appendix D shows two additional features, both when MECH=STRUCT is being used:

1. The PERQ option of field 9 was activated.

2. Field 7 (LSET) can point to any type of loading whereas previously it could only select FORCE of MOMENT load types.

Two other enhancements applicable to AEDW and AEPRESS entries as well as AEFORCE:

The first is in the nature of the correction in a design flaw. In previous releases of MSC.Nastran, if a UXVEC entry only contained Label INTERCPT with a value of 1.0, the forces were added to all v-space terms that included the intercept. This has been corrected so that the forces are only present for the INTERCPT state.

The second is if AExxxx (i.e., AEFORCE/AEDW/AEPRESS) entries that point to the same UXVEC are summed. Previously only a single AExxxx/UXVEC combination was permitted.

BenefitsWith these enhancements, the user can now sum forces from a series of AExxxx entries to achieve a single controller. For example, there may be wind tunnel results on a number of components (e.g., missiles and fuselage segments) at a unit angle of attack that are not included in the aerodynamic model. Multiple AEFORCE entries that point to a single UXVEC vector that has INTERCPT and ANGLEA terms can now be used to add these effects in the simulation. Note that the LSET call out can also refer to a LOAD Bulk Data entry so that load superposition can occur and the import load feature of Section x.1 can be utilized.

The benefit of the ID=”ALWAYS” on the AELINK entry is significant when hundreds of subcases are run in a single job submittal.


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Input/OutputThe introduction has already described the changes available on the AELINK, AEDW, AEFORCE and AEPRESS entries. There is no change in the output due to these enhancements.

Guidelines and LimitationsAExxxx entries that point to the same combination of control point values are summed. For example, AEFORCE entries that are for the same Mach and symmetry and either point to the same UXID or point to different UXID’s that have identical control point values all act together. AEFORCE entries that have MESH=AERO are combined with entries with MESH=STRUCT in this fashion.

Examples (aelinka.dat, aelinkb.dat,i3fusa.dat,aepload4.dat,fusae.dat)Aelinka.dat shows how ALWAYS can be used to make the linking condition apply to all subcases while aelinkb.dat has one controller using the ALWAYS feature while another has subcase dependent linking so that a scheduled deployment can be simulated.

i3fusa.dat is a variation of tpl file osprey.dat. It removes the engine controllers but adds user input aerodynamics for the fuselage at the intercept. The following fragment of this file shows how this concept is implemented:

$ aerodynamics on the fuselage at zero angle of attack $ using an aeforce/uxvec combination with no perq$ since the uxvec vector only reference the intercept, these $ forces are added to the intercept value and nowhere else. $aeforce0.9asymmasymm5011struct5011uxvec5011intercpt1.0 force 50119712000.0.00.01.0force 50119860000.0.00.01.0force 50119930000. 0.00.01.0

The results of running this file show that the forces produced by these data are applied only to the intercept state and not to the remaining states, such as ANGLEA.

Aepload4.dat uses pressure loads in conjunction with an AEFORCE entry while fusae.dat demonstrates that the AEFORCE entry with a UXVEC that specifies ANGLEA and INTERCPT with a value of 1.0 with add the additional forces to the angle of attack. Previously, it was necessary to include and AEPARM and a separate controller to add this type of force into the analysis.


Separate Rigid and Flexible Aero Meshes

IntroductionMSC.Nastran has been enhanced to support the ability to generate the rigid aerodynamic loads on one mesh while the aeroelastic increments are generated from a second mesh.

BenefitsThis enhancement adds to the infrastructure of the static aeroelastic analysis of SOL 144, but is not accompanied by any immediate useful application. A possible application would be to use CFD generated or wind tunnel derived aerodynamics to provide the rigid loads while the aeroelastic increments could be generated using the current aerodynamic methods in MSC.Nastran. Having the concept of separate rigid and flexible meshes available does simplify the task of incorporation these alternative aerodynamics using a customized solution.

InputThe AERCONFIG Case Control command is provided to identify the aerodynamic configuration that represents the rigid aerodynamics. The use of this command can be demonstrated by making two separate runs: the first contains the rigid mesh and is run with SCR=NO to save the needed data blocks. The AECONFIG command is used to identify this mesh. The second run inputs the flexible mesh using standard bulk data input and the AECONFIG command while the flexible mesh is input using a combination of DBLOCATE statements and the AERCONFIG command to identify the rigid mesh. See the example below for the DBLOCATE requests.

OutputThe following data related to aeroelastic results are written to the DBC and are therefore available in the .xdb output:

Datablock Description Mesh

UKS Trimmed displacements Flexible

PERKS Trimmed forces Flexible

FFERJS Trimmed pressures Flexible

RUKS Trimmed displacements Rigid

PRKS Trimmed forces Rigid

FFRJS Trimmed pressures Rigid

UERVKS Unit solution restrained displacements Flexible


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UEUVKS Unit solution unrestrained displacements Flexible

RUERVKS Unit solution restrained displacements Rigid

RUEUVKS Unit solution unrestrained displacements Rigid

PERVKS Unit solution restrained forces Flexible

PEUVKS Unit solution unrestrained forces Flexible

FERVJS Unit solution restrained pressures Flexible

FEUVJS Unit solution unrestrained pressures Flexible

PRVKS Unit solution rigid forces Rigid

FRVJS Unit solution rigid pressures Rigid

Datablock Description Mesh


Miscellaneous Aeroelastic Enhancements

Revision in the Aerodynamic Splining to the StructureStarting with MSC.Nastran 2005 r3, the splining that transfers the loads from the aerodynamic to the structural models in static aeroelastic analysis (SOL 144 and SOL 200) occurs in the f-set. Previously, this had been done in the g-set. This should not results in any change in results unless some of the structural degrees of freedom that are being splined to part of the single point constraint set. Previously, this load was reported in the rigid splined airloads, but now it will be discarded. Therefore, if the rigid splined and unsplined derivatives agreed in the past but now differ, you need to examine the model to see if you are splining to constrained dof’s and, if so, that is your intent.

Flutter Analysis with Singular Mass MatricesA long time requirement of the PK and KE flutter methods is that the diagonal terms of the mass matrix must be non-zero. This was a requirement of the underlying eigenanalyses being used and presented a problem with the modeling of control systems using the TF Bulk Data entry. As indicated by the servoelastic test case of Estimation of Dynamic Stability Derivatives (Example HA145I) (Ch. 8) in the MSC.Nastran Aeroelastic Analysis User’s Guide, this created a requirement that the transfer functions be differentiated a sufficient number of times to create a non-zero B0 term. This introduces additional zeroes in the eigensolution that can be ignored, but that complicate the interpretation of the results. An alternative QZ algorithm, as developed in Reference 1 (C. Moler and G.W. Stewart, “An Algorithm for Generalized Matrix Eigenvalue Problems,” SIAM J. Numerical Analysis, 10:241-256, 1973) has been implemented into the flutter solutions in MSC.Nastran that removes the requirement that the mass matrix be non-singular. The result is that test cases that used to require differentiation to make the mass matrix non-singular can now input the transfer functions in their original form. The results should be identical in either case so that this enhancement should not result in different answers for existing files. If you wish to investigate whether the new eigenanalysis methods are giving different answers, the old method are still available by setting Nastran System Cell 108 to 1.


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Ch. :

7 Optimization

! Topology Optimization with Manufacturability Constraints, 138

! Revised Optimizer Options, 154

! Supporting Trust Region in SOL 200 for Adaptive Move Limits, 157

! Support of Analysis Model Value Overriding Design Model Value, 164


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Topology Optimization with Manufacturability Constraints

Introduction Topology optimization is a powerful tool to generate design concepts in the early design stage. A topology optimization Beta capability was introduced in MSC.Nastran 2005 while the formal capability was released in MSC.Nastran 2005 r2. MSC.Nastran 2005 r3 contains substantial enhancements to this capability that provides a number of manufacturability constraints to aid in producing designs that are more practical in terms of actually manufacturing the proposed design. The constraints include minimum member size, symmetry constraints, casting constraints (also called draw direction constraints), and extrusion constraints.

A review of the topology optimization section in MSC.Nastran 2005 or the MSC.Nastran2005 r2 Release Guide is recommended if you are new to MSC.Nastran’s implementation of this technology. This document emphasizes applications of manufacturability constraints.

Benefits

Minimum Member Size (Constraints)

The minimum member size constraint is mainly used to control the size of members in topology optimal designs. By avoiding thin members enhances the simplicity of the design and hence its manufacturability. Minimum member size is more like quality control than quantity control.

Casting Constraints (Draw Direction Constraints)

Topology optimized designs can contain cavities that are not achievable by casting or some machining processes. The casting constraints allow users to impose die draw direction constraints and prevent hollow profiles so that the die can slide in a given direction.

Extrusion Constraints

It is often desirable to produce a design with a constant cross-section along a given direction. This constraint is particularly essential for a design manufactured through an extrusion process. By using the extrusion manufacturing constraints in topology optimization, constant cross-section designs can be obtained for solid models regardless of the boundary conditions, loads, and finite element mesh.

Symmetry Constraints

It is often desirable to design a symmetric component or system. However, regular topology optimization cannot guarantee a perfect symmetric design, even if the design space, boundary conditions, and loads are symmteric. By using symmetry constraints in topology optimization, a symmtric design can be obtained regardless of the boundary conditions or loads. These symmetric constraints can also be used for irregular finite element meshes.

139CHAPTER 7Optimization

CASI Iterative Solver

As detailed in the New Iterative Solver Option (Ch. 3) of this Guide, the CASI iterative method can provide a major speedup in the solution of large (>3 million dof) static analyses. This benefit has been extended to topology optimization with compliance responses.

Input The TOPVAR Bulk Data entry has been enhanced to provide manufacturing constraints. To select a topologically designable region, the user needs to specify a group of elements by using a Bulk Data entry, TOPVAR. All elements that reference property ID given on a TOPVAR entry are topologically designable. Topology design variables are automatically generated with one design variable per designable element. The manufacturability constraints are then applied on all elements referencing the given property ID.

The basic format for TOPVAR is:

1 2 3 4 5 6 7 8 9 10

TOPVAR ID LABEL PTYPE XINIT XLB DELXV POWER PID

“SYM” CID MSi MSi MSi

“CAST” CID DDi DIE

“EXT: CID EDi

“TDMIN” TV

Field Contents

ID Unique topology design region identification number. (Integer > 0)

LABEL User-supplied name for printing purpose. (Character)

PTYPE Property entry name. Used with PID to identify the elements to be designed. (Character: “PBAR”, “PSHELL”, ‘PSOLID”, etc.)

XINIT Initial value. (Real, XLB < XINIT). Typically, XINIT is defined to match the mass target constraint, so the initial design does not have violated constraints. For example, if the mass target is 30% on DRESP1=FRMASS, then it is recommended XINIT=0.3.

XLB Lower bound to prevent the singularity of the stiffness matrix. (Real; Default = 0.001)

DELXV Fractional change allowed for the design variable during approximate optimization. (Real > 0.0; Default = 0.2. See Remark 3).

POWER A penalty factor used in the relation between topology design variables and element Young’s modulus. (Real > 1.0; Default = 3.0). 2.0 < POWER < 5.0 is recommended.

PID Property entry identifier (Integer > 0)


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Remarks:1. The topologically designable element properties include PROD, PBAR, PBARL, PBEND,

PBEAM, PBEAML, PSHELL, PSHEAR, PSOLID, and PWELD. Multiple TOPVAR’s are allowed in a single file.

2. All designed element properties must refer to a MAT1 entry; therefore, a PCOMP cannot be used as designed property in topology optimization. PCOMP’s can be used as non-designed properties in a topology optimization job.

3. If DELXV is blank, the default is taken from the specification of DELX parameter on the DOPTPRM entry.

4. Only CORD1R and CORD2R can be used as a referenced coordinate system to specify topology manufacturing constraints. Only one reference coordinate system CID is allowed for each TOPVAR entry.

5. One, two or three different mirror symmetry planes can present (such as MS1=XY, MS2=YZ, and MS3=ZX).

“SYM” Indicates that this line defines symmetry constraints.

CID Rectangular coordinate system ID used for specifying manufacturing constraints. See Remark 4 (Blank or Integer > 0; Default = 0 = the basic coordinate system)

MSi Mirror symmetry plane. See Remark 5 & 7 (Character, ‘XY’, ‘YZ’, or ‘ZX’)

“CAST” Indicates that this line defines casting constraints (i.e., die draw direction constraints). See Remarks 6 and 7.

DDi Draw Direction. DDi=X, Y, Z or X-, Y-, Z- for a single die option (DIE=1) where X-, Y-, Z- indicates the opposite direction of X, Y, and Z respectively. DDi=X, Y, and Z for two die option (DIE =2) (Character)

DIE Die Options. (Blank or integer 1 or 2; Default = 1)

= 1 (or blank). A single die will be used and the die slides in the given draw direction (i.e., material grows from the bottom in the draw direction)

= 2. Two dies will be used and the dies split apart along the draw direction (i.e., material grows from the splitting plane in opposite direction along the axis specified by the draw direction DDi. The splitting plane is determined by optimization)

“EXT” Indicates that this line defines extrusion constraints (i.e., enforce constant cross-section) See Remark 6 and 7.

EDi Extrusion direction. (Character, X, Y, or Z)

“TDMIN” Indicates that this line defines a minimum member size, See Remarks 9 and 10.

TV Minimum member size. See Remark 9. (Real > 0.0)

Field Contents


6. Casting (“CAST”) and Extrusion (“EXT”) manufacturability constraints can be applied to PTYPE=”PSOLID” only. Casting constraints cannot be combined with extrusion constraints for the same TOPVAR entry.

7. Some symmetry constraint types can be combined with casting or extrusion constraints. The referenced coordinate system CID must be the same for the combined constraints. Some possible combinations are:

For “EXT” constraints, possible combinations are (EDi=X, MSi=XY and/or ZX), (EDi=Y, MSi=YZ and/or XY), (EDi=Z, MSi=ZX and/or YZ).

For “CAST” constraints, possible combinations are (DDi=X or -X, MSi=XY and/or ZX), (DDi=Y or -Y, MSi=YZ and/or XY), (DDi=Z or -Z, MSi=ZX and/or YZ).

8. For two dies option (DIE=2), the splitting plane is optimized. For a single die DIE=1, the parting plane is the bottom surface of the designed part in the draw direction.

9. TDMIN is a dimensional quantity with a guideline that it be set to at least three times a representative element dimension.

10. Without a TDMIN continuation line, the minimum member size constraint is taken from the specification of TDMIN parameter on the DOPTPRM entry. This option is applied on 2 and 3 D elements only. Minimum member size constraints can be used with “SYM”, “CAST”, and “EXT” constraints.

Minimum Member Size Parameter TDMIN

TDMIN on Bulk Data entry TOPVAR is allowed users to define an individual minimum member size for each designed property. A parameter TDMIN on the DOPTPRM entry is introduced to allow users to define a minimum member size applied for all TOPVAR entries that do not have the TDMIN continuation line.

Invoking the CASI Iterative Solver

The CASI Iterative Solver is invoked in topology optimization in one of two ways:

1. Specifying SMETHOD=ELEMENT in Case Control for an ANALYSIS=STATICS subcase.

2. Specifying SMETHOD=IID in Case Control for an ANALYSIS=STATICS subcase where IID identifies and ITER Bulk Data entry that can be used to override default options when using the iterative solver.

Table 7-1 DOPTPRM Design Optimization Parameter: TDMIN

Name Description, Type and Default Value

TDMIN Minimum diameter of members in topology optimization (real >0.0). This option is applied on 2 and 3 D elements only.


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Guidelines and Limitations• The casting constraints may have difficulty dealing with a design model that has one or more

non-smoothed boundary surfaces to be designed. It is recommended to use smooth top surface in the draw direction for one die casting constraints, and smooth top and bottom surfaces in the draw direction for two die casting constraints.

• MSC.Patran 2005 r2 can smooth, remesh, and generate IGES files for 2D topology designs and smooth 3D topology designs.

• MSC.Patran 2005 r3 can support topology optimization with manufacturability constraints.

• The use of the CASI iterative solver for topology optimization is subject to all the limitations listed in Chapter 3 for this capability. In addition, only the compliance response can be invoked at the subcase level. That is, the design task is to minimize the compliance for a specified fractional mass.


Example 1 – MBB Beam Baseline (topex3.dat)An MBB beam example (a half model shown in Figure 7-1) is used to demonstrate basic MSC.Nastran topology optimization capabilities without manufacturing constraints. The structural compliance is minimized with a mass target 0.5 (i.e., remove 50% of the material). The loading and boundary conditions are shown in Figure 7-1. The structure is modeled with 4800 CQUAD4 elements.

Figure 7-1 MBB Beam

Input

The input data for this example related to topology optimization model is given in Listing 7-1.

Listing 7-1 Input File for Example 1

DESOBJ = 1DESGLB = 1SUBCASE 1$ Subcase name : Default SUBTITLE=Default SPC = 2 LOAD = 2 ANALYSIS = STATICSBEGIN BULKDCONSTR 1 2 .5TOPVAR, 1 , Tshel, Pshell, .5, , , , 1DRESP1 1 COMPL COMP DRESP1 2 FRMASS FRMASS


144

Output

Figure 7-2 shows the topology optimized result that is smoothed and remeshed by using MSC.Patran 2005 r2. It is noticed that there are some small members.

Figure 7-2 MBB Beam Topology Design


Example 2 - MBB Beam with Minimum Member Size (topex3a.dat)The MBB beam (shown in Figure 7-1) is used here to demonstrate the minimum member size capability.

Input

The input data for this example related to topology optimization with “minimum member size” is given in Listing 7-2. The minimum member size value is defined by the parameter TDMIN = 0.5 on the DOPTPRM entry and corresponds to the length of 10 elements.


DESOBJ = 1DESGLB = 1SUBCASE 1$ Subcase name : Default SUBTITLE=Default SPC = 2 LOAD = 2 ANALYSIS = STATICSBEGIN BULKDOPTPRM, TDMIN, 0.5DCONSTR 1 2 .5TOPVAR, 1 , Tshel, Pshell, .5, , , , 1DRESP1 1 COMPL COMP DRESP1 2 FRMASS FRMASS

Output

Figure 7-3 shows the topology optimized result with “minimum member size” TDMIN=0.5. Compared the design shown in Figure 7-2, this design with “minimum member size” is obviously much simpler and there are no tiny members at all.

Figure 7-3 MBB Beam Topology Design with “Minimum Member Size”


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Example 3 - MBB Beam with Symmetric Constraints (topex3b.dat)Since the loads applied on the MBB beam are not symmtric, the topology optimized designs Figure 7-2 and Figure 7-3 are not symmetric. The MBB beam is employed again to demonstrate the symmetric constraint capability that enforces the design to be symmetric about a given plane.

Input

To apply symmetric constraints on designed properties, users need to create a reference coordinate system using a rectangular coordinate system CORD1R or CORD2R. In this example, grid 10001 (location x=3, y=1, and z=0) is defined as the origin. Grid 10002 (x=3, y=1, and z=1) lies on the z-axis, and grid 1003 (x=4, y=1, and z=0) lies in the x-z plane. CORD1R CID=1 defines a reference coordinate system. A continuation line “SYM” enforces the property PSHELL=1 to be symmetric about the planes YZ and ZX in the reference coordinate system CID=1. In addition, a minimum member size TDMIN=0.15 is applied. The input data for this example is given in Listing 7-3.


DESOBJ = 1DESGLB = 1SUBCASE 1$ Subcase name : Default SUBTITLE=Default SPC = 2 LOAD = 2 ANALYSIS = STATICSBEGIN BULKCORD1R 1 10001 10002 10003GRID 10001 3. 1. 0.0GRID 10002 3. 1. 1.0GRID 10003 4. 1. 0.0TOPVAR, 1 , Tshel, Pshell, , , , , 1 , SYM , 1 , YZ , ZX

, TDMIN, 0.15DRESP1 1 COMPL COMP DRESP1 2 FRMASS FRMASS DCONSTR 1 2 .5

Output

Figure 7-4 shows the topology optimal result with symmetric constraints and minimum member size.


Figure 7-4 MBB Beam with Symmetric Constraints and Minimum Member Size


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Example 4 - A Torsion Beam with Extrusion Constraints (topex5.dat)A torsion beam is used here to demonstrate the extrusion constraints. The Figure 7-5 shows the FEM model of the torsion beam. A pair of twisting forces is applied on one end while the other end is fixed. 2048 CHEXA elements are used for this model. The objective is to minimize the structural compliance with mass target of 0.3 (i.e., remove 70% material).

Figure 7-5 Torsion Beam

Input

The extrusion constraints enforce a constant cross-section design along the given extrusion direction. The input data related to imposing an extrusion constraint along the z-axis in the basic coordinate system (as the default option) is given in Listing 7-4.


DESOBJ = 1DESGLB = 1SUBCASE 1$ Subcase name : Default SUBTITLE=Default ANALYSIS = STATICS SPC = 2 LOAD = 2


$ Direct Text Input for this SubcaseBEGIN BULKDRESP1 2 Frmass FRMASSDRESP1 1 COMPL COMPDCONSTR 1 2 .3TOPVAR, 1 , TSOLID, PSOLID, .3, , , , 1 , EXT , , ZPSOLID 1 1 0

Output

Figure 7-6 shows the topology optimized result with extrusion constraints. It is obvious that the design has a constant cross-section along the z-axis.

Figure 7-6 Torsion Beam with Extrusion Constraints in Z-Axis


150

Example 5 - A Torsion Beam with One Die Casting Constraints (topex5a.dat)A torsion beam (shown in Figure 7-5) is used here to demonstrate the combination of one die casting manufacturability constraints and symmetric constraints. It also demonstrates the use of the iterative solver.

Input

The casting constraints with one die option enforce the material can only be added to the region by “filling up” in the given draw direction from the bottom (or, stated another way, that voids extend from the top surface and do not reappear in the die direction). To apply casting constraints and symmetric constraints on designed properties, a reference coordinate system CID=1 is defined by using a rectangular coordinate system CORD1R. A “CAST” continuation line defines casting constraints in the Y direction and one die is a default option. Another “SYM” continuation line defines symmetric constraints about the YZ plane. The input data related to the topology optimization model is given in Listing 7-5.


DESOBJ = 1DESGLB = 1SUBCASE 1$ Subcase name : Default SMETHOD=ELEMENT

SUBTITLE=Default ANALYSIS = STATICS SPC = 2 LOAD = 2$ Direct Text Input for this SubcaseBEGIN BULKDRESP1 2 Frmass FRMASSDRESP1 1 COMPL COMPDCONSTR 1 2 .3CORD1R 1 5 167 7PSOLID 1 1 0TOPVAR, 1 , TSOLID, PSOLID, .3, , , , 1

, CAST, 1 , Y, SYM, 1 , YZ

PSOLID 1 1 0

Output

Figure 7-7 shows the topology optimized result with one die casting constraints. It is observed that the design material is added by “filling up” in the Y direction from the bottom. In addition, the design is symmetric about the YZ plane in the reference coordinate system CID=1.


Figure 7-7 Torsion Beam with One Die Casting Constraints in Y Direction


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Example 6 - A Torsion Beam with Two Die Casting Constraints (topex5b.dat)A torsion beam (shown in Figure 7-5) is also used here to demonstrate two die casting manufacturability constraints.

Input

The input for two die casting constraints is similar to the one die option in Example 5. Here, the difference is that 2 are selected for the DIE field on the TOPVAR entry. The input data related to imposing two die casting constraints is given in Listing 7-6.


DESOBJ = 1DESGLB = 1SUBCASE 1$ Subcase name : Default SUBTITLE=Default ANALYSIS = STATICS SPC = 2 LOAD = 2$ Direct Text Input for this SubcaseBEGIN BULKDRESP1 2 Frmass FRMASSDRESP1 1 COMPL COMPDCONSTR 1 2 .3CORD1R 1 5 167 7PSOLID 1 1 0TOPVAR, 1 , TSOLID, PSOLID, .3 , , , , 1

, CAST, 1 , Y, 2, SYM , 1 , YZ

PSOLID 1 1 0

Output

Figure 7-8 shows the topology optimized result with two die casting constraints. It is observed that the design material grows from the splitting plane in opposite directions along the y-axis specified in the reference coordinate system CID=1. The splitting plane is determined by optimization and in this case corresponds to the


Figure 7-8 Torsion Beam with Two Die Casting Constraints in Y-Axis


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Revised Optimizer Options

IntroductionMSC.Nastran 2005 r3 has made MSCADS the default optimizer for the Design Optimization in Solution 200. This provides MSC with greater flexibility in maintaining and enhancing the optimization algorithm relative to the DOT optimizer that is licensed from Vanderplaats Research & Development, Inc. (VR&D) and has been the mainstay algorithm for many years. DOT is still available as an option that requires explicit selection by the user. MSCADS is MSC.Software’s version of the ADS (Automated Design Synthesis) code, a public domain FORTRAN program developed by Dr. G. N. Vanderplaats while he was on the faculty of the Naval Postgraduate School under a contract from the Navy and NASA/Langley. Dr. Srinivas Kodiyalam provided MSC.Software with his enhanced version of the ADS source code at no cost.

The topology optimization of the previous section typically involves thousands of design variables (the simple MBB beam, for example, has 4800 independently designed elements). The MSCADS and DOT optimizers are intended for problems with much fewer design variables, with 3-4000 considered a practical upper limit. For this reason, MSC recommends that serious users of the topology optimization capability consider acquiring the Topology Optimization option, which contains the BIGDOT optimizer, also from VR&D. This code has been shown to be capable of handling tens of thousands of design variables while considering numerous constraints. At the same time, it must be stated that it is not strictly necessary to acquire the Topology Optimization option in order to apply topology optimization. A preliminary assessment of this capability on limited sized problems can be made using only the Design Optimization option. It is necessary in this case to explicitly select the MSCADS or DOT optimizer as outlined in the Input subsection below, in this case since the default when there are TOPVAR Bulk Data entries is to use BIGDOT.

BenefitsThe MSCADS optimizer provides numerous options for performing design optimization that can be explored. The BIGDOT optimizer not only enables performing practical topology optimization tasks but can also be used to perform standard shape and sizing optimization for design tasks with many thousands of design variables. This latter capability requires that both the Topology Optimization and the Design Optimization options be available.

InputThere are two ways to select the optimizer code. One way is by modifying an executive system parameter OPTCOD in the Runtime Configuration (RC) file as shown in Table 7-2.


The second way is by a new parameter OPTCOD added to the DOPTPRM Bulk Data entry that has options shown in Table 7-3. The parameter METHOD is used to select optimization methods.

Table 7-2 System Cell Summary

System Cell Number

System Cell Name Description and Default Value

413 OPTCOD Specifies which optimization code to be used

in SOL 200 (Default = 0)

0 – MSCADS (Design Optimization Option) and BIGDOT (Topology Optimization Option)

1 – DOT Optimizer

2 – BIGDOT Optimizer

Table 7-3 DOPTPRM Design Optimization Parameters

Name Description, Type, and Default Values

OPTCOD OPTCOD (Character; Default= Blank)

= Blank (taken from system cell number 413)

= "MSCADS" : MSCADS is used

= "DOT" : DOT is used

= "BIGDOT" : BIGDOT is used

METHOD Optimization Method: (Integer > 0; Default = 1)

= 1 Modified Method of Feasible Directions for both MSCADS and DOT

= 2 Sequential Linear Programming for both MSCADS and DOT

= 3 Sequential Quadratic Programming for both MSCADS and DOT

= 4 SUMT method for MSCADS

= IJK for user's specified MSCADS optimization strategy. (see the MSC.Nastran 2005 Release Guide)


156

OutputThere are no outputs that are affected by optimizer selection with the exception that the optimizer output produced using the IPRINT parameter on the DOPTPRM entry is dependent on the method selected. In particular, the banner for the MSCADS code appears as:

M S C . A D S

E N H A N C E D A D S P R O G R A M

F O R

A U T O M A T E D D E S I G N S Y N T H E S I S

Guidelines and LimitationsThe optimization results from MSCADS are expected to be comparable to those from DOT. If this is not the case, the OPTCOD parameter can be used to invoke the DOT optimizer.

It is recommended that the Topology Optimization option be utilized for topology optimization and for sizing and shape optimization problems with thousands of design variables.

Sizing and shape cannot be combined with topology optimization in a single run.


Supporting Trust Region in SOL 200 for Adaptive Move Limits

IntroductionFormal approximate optimization is used in SOL 200 to find a new design without performing expensive and exact finite element analyses (Ref. 1, Chapter 2.7). However, move limits must be applied to define a restricted region on which an adequate approximate model can be created.

Convergence checks are made following each approximate optimization task. Currently, if the approximate optimization comes up with a design that an exact analysis shows is actually worse, it is assumed that the region defined by move limits are too generous and they are reduced. Using Trust Region Concepts, this simple update strategy can be improved in three fundamental ways:

1. A merit function is applied to provide a more quantitative measure of the quality of the approximation.

2. A provision is made to increase the move limits when the approximate optimization results are shown to be of high quality.

3. If the new design is judged to actually be worse, it is discarded and the approximate optimization task is performed again with tighter move limits.

BenefitsSince the move limits can be either reduced or increased in an adaptive fashion, it is expected that the quality of the approximate model will be enhanced. This should lead to more robust optimization result and faster convergence. In addition, rejecting a bad design should also smooth the design optimization process.

Theory

Concept of Trust Region

The main idea behind the Trust Region is to first compute a merit function that is a combination of the objective function and the maximum violated constraint value and then form a ratio of the exact reduction in a merit function to the predicted reduction in the merit function. The ratio can be written as follows, assuming a design task is a constrained minimization optimization task:

RatioMFp MFc–

MFp MFa–------------------------------=


158

where:

Notice that a merit function is the sum of objective and the product of penalty weight and the

maximum violated constraint . Subscripts c, p and a, indicate that the function is evaluated exactly at the current design cycle, evaluated exactly at the previous design cycle and evaluated approximately, respectively. The penalty weight plays an important role in a successful optimization task with Trust Region Method.

The magnitude of Ratio varies in the real interval of . The denominator is the predicted reduction in merit function while the numerator is the exact reduction in merit function. Since we consider the case of minimizing the objective, the denominator should always produce a positive number to indicate that the optimizer has done a good job.

Different Ratio values can measure the quality of the approximate model. For example, a negative Ratio (likely due to negative numerator) indicates that the approximate model is so bad that the exact merit function is greater than the previous exact. Thus reducing move limits is necessary. On the other hand, Ratio = 1 indicates the approximate model is very good that the predicted reduction is identical to the exact reduction and the move limits can be increased. In general, the following strategies are used to update move limits if:

1. Ratio < (say 0.01), reject the design, cut the move limits in half and repeat the approximate optimization task. For a minimization task, the reduction in the merit function must be greater than zero. A too small or negative Ratio indicates that the new design proposed by the approximate model either does not reduce the merit function, or the quality of the approximate model is very poor.

2. < Ratio < (say 0.25), accept the design, but cut the move limits in half for the next approximate design task. The ratio in this range indicates that quality of the approximate model is not good enough, or the current move limit is still too large.

3. < RATIO < (say 0.75), accept the design and do not adjust the move limits.

4. Ratio > , accept the design, but increase the move limits by 50%, up to a pre-specified upper value. The ratio approaching to 1 indicates that the approximate model I is accurately predicting the actual behavior. Therefore, the current move limits can be increased. In addition, although Ratio > 1 indicates that the approximate model is not particularly accurate, but it predicts in the right direction so that larger move limits can also be used.

Creating the Constrained Merit Function

For the unconstrained minimization tasks, the merit function is simply the objective. For constrained minimization tasks, the second term on the right hand side of the merit function accounts for violated constraints. Since Ratio is computed using three merit functions, according to Ref. 2, the approximate

The current exact merit function

The previous exact merit function

The approximate merit function.

MFc Φc= PW maxgc⋅+

MFp Φp= PW+ maxgp⋅MFa Φa= PW+ maxgc⋅

Φ( )g( )

∞ ∞,–( )

η1

η1 η2

η2 η3

η3


optimization problem should also be solved in the same fashion to minimize the merit function that is

formed by the objective and the corresponding 2nd term. A capability to transform an approximate optimization task to a feasible design was implemented in the MSC.Nastran 2005 (Ref. 3, Chapter 6.3) and can be readily used here to satisfy this consistency requirement. Notice that the algorithm of Ref. 3 computes the penalty weight, , where is the starting objective at the beginning of the

approximate optimization job, while here PW is obtained with a single number (See Penalty Weight Section).

Penalty Weight

Penalty Weight (PW) is used to form the merit function. The penalty weight plays an important role in a successful optimization task with Trust Region Method. It is problem dependent. The larger it becomes, the more the maximum violated constraint is penalized. There are two ways to define PW: automatic and user specified. For the automatic way, PW = 10 * the initial objective from the initial design cycle. This is the default option. Alternatively, the user can provide his own through a Bulk Data Parameter, MXLAGM1 (See Input Section). Then, PW = 10.* MXLAGM1.

Rejecting a Design

If Ratio < , the current design will be rejected. When the flag is set, the subsequent design sensitivity

phase will be skipped and the approximate optimization job will be performed based on the previous good design with reduced move limits.

Input

New Parameters added to the DOPTPRM entry

TREGION Flag to invoke Trust Region method.

= 0 (Default) Don’t employ trust regions

= 1 turn Trust Region on

ETA1 ( ) the cutting ratio 1 (Default = 0.01), used by Trust Region Method.



UPDFAC1 Updating Factor 1 (Default = 2.0), used by Trust Region Method.

UPDFAC2 Updating factor 2 (Default = 0.5), used by Trust Region Method.

DPMAX Maximum fraction of change on designed property (Default = 0.5) , used by Trust Region Method.

DXMAX Maximum fraction of change on design variable (Default = 1.0), used by Trust Region Method.

PW Penal= Φo⋅ Φo

η1

η1

η2

η3


160

Bulk Data Parameter

PARAM,MXLAGM1,VALUE - Control parameter for Penalty Weight (Real, Default = 0.0).

Outputs

Special Printout from DOM12

If Trust Region method is invoked, DOM12 prints out additional information message as shown below. This message is printed out once every design cycle. The left column is design cycle number. It prints out Objective, Maximum violated constraint and merit function for exact current, exact previous and approximate. It further prints out Ratio together with numerator, denominator. It also prints out the final Update factor for move limits plus the rejecting status. Finally, it prints out current move limits for property and design variable ply penalty weight.

Marker Indicating a Rejected Design in Design History

A rejected design will be marked by adding symbol ‘R’ to the design cycle number shown in the Summary of Design Cycle History at the end of f06 file. Below is an example that shows design cycle 2 has been marked with ‘R’. This is because although this design produces a smaller objective but with the violated constraint. So the design is rejected. Design cycle 1 is used as the next starting design point.

DCYCL OBJECTIVE MAX-CONS MERIT-FUN NUMER DENOM RATIO UPFAC REJ-FLAG TTTT

2 PREV 6.893711E+00 2.133793E+01 1.477869E+03 5.0832E+02 5.0839E+02 9.9987E-01 2.0000E+00 0 TTTT CURR 9.935308E+00 1.392006E+01 9.695438E+02 TTTT

APPX 9.935904E+00 1.391907E+01 9.694761E+02 TTTT MOVEP,MOVP-MIN = 5.000000E-01 1.000000E-02 TTTT

MOVEX,MOVX-MIN = 1.000000E+00 5.000000E-02 TTTT

NDOFs(NDV-NACS)= 0 TTTT PENAL WEIGHT = 0.6894E+02 TTTT

*************************************************************** S U M M A R Y O F D E S I G N C Y C L E H I S T O R Y ***************************************************************

(HARD CONVERGENCE ACHIEVED)

NUMBER OF FINITE ELEMENT ANALYSES COMPLETED 16 NUMBER OF OPTIMIZATIONS W.R.T. APPROXIMATE MODELS 15

OBJECTIVE AND MAXIMUM CONSTRAINT HISTORY --------------------------------------------------------------------------------------------------------------- OBJECTIVE FROM OBJECTIVE FROM FRACTIONAL ERROR MAXIMUM VALUE CYCLE APPROXIMATE EXACT OF OF NUMBER OPTIMIZATION ANALYSIS APPROXIMATION CONSTRAINT ---------------------------------------------------------------------------------------------------------------

INITIAL 6.614414E+02 1.102773E-01

1 5.987441E+02 5.987546E+02 -1.743120E-05 -4.438843E-04

2R 5.475672E+02 5.475823E+02 -2.764282E-05 2.106060E+00

3 5.626934E+02 5.627052E+02 -2.104267E-05 -3.308058E-04


Guidelines and Limitations1. All new parameters introduced in the DOPTPRM have their own defaults and are usually

adequate. If you want the optimization job to have more aggressive move limit, you may do so by reduce ETA3 and/or increase DPMAX and DXMAX or increase UPDFAC1. Conversely, you may increase ETA3 and/or reduce DPMAX, DXMAX and/or decrease UPDFAC1.

2. A non-zero MXLAGM1 is used to override the default Penalty Weight (PW). This parameter is problem dependent and may require some iteration to come up a good number. When the need arises to specify one, a general rule is to specify a bigger number (say 100. and larger) for the maximum constraint is grossly violated.

3. In some cases, it is possible that activating Trust Region in SOL 200 may produce less desirable result than a non-Trust Region job.

Examples The example (dtrustr2.dat) is a Stiffened Panel constrained optimization job taken from the testing problem library (d200x7.dat). It tries to minimize a weight response while satisfies stress and displacement constraints. The same job was run with and without Trust Region (TR). The Trust Region is invoked by specifying TREGION=1 on the DOPTPRM entry. In addition, the parameter MXLAGM1 is set to 10.

Figure 7-9 plots the objective history and DELX history with and without TR. The TR job converges at design cycle 15 (notice that plots count initial design cycle as 1 that is actually zero if counted in the f06) while the non-TR job converges at design cycle 27. Both has same final objective function with maximum feasible constraint at the tolerance of GMAX=0.5%. The fast convergence achieved by the TR job may be explained by the DELX history shown at the bottom of Figure 7-9. The non-trust region job uses a constant move limit (e.g., DELX=0.5) while the DELX in the trust region job is adaptively updated: between design cycles 2 and 6, DELX=1.0 and then reduced below 0.5 between design cycles 8 and 14. Finally, Figure 7-10 plots the maximum constraint values with and without TR. Listing 7-7 lists the summary of the design history.


162

Figure 7-9 Objective History of Example 2: Trust Region vs. Non-Trust Region

Figure 7-10 Max. Constraint History of Example 2: Trust Region vs. Non-Trust Region

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

0 5 10 15 20 25 30

Design Cycle

Ob

ject

ive

0.00.51.01.52.02.53.03.54.04.55.05.56.0

Fra

ctio

n o

f M

ove

Lim

it

OBJ-TR OBJ-NTR DELX-TR DELX-NTR

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 5 10 15 20 25 30

Design Cycle

Max

imu

m C

on

stra

int

MaxC-TR MaxC-NTR


Listing 7-7 Table Summary of Objective and Maximum Constraints

References1. _____, MSC.Nastran 2004 Design Sensitivity and Optimization User’s Guide, MSC.Software

Corporation, Santa Ana, CA., 2003

2. MSC.Nastran 2005 Release Guide, MSC.Software Corporation, Santa Ana, CA., 2004

3. Prof. L. Lasdon, private communication, Dec. 13, 2004.

INITIAL 5.784520E+00 1.291873E+00 1 8.610938E+00 8.610291E+00 7.509516E-05 6.616151E-01 2 6.194046E+00 6.193711E+00 5.412208E-05 5.258847E-01 3 7.550942E+00 7.550880E+00 8.146334E-06 2.141915E-01 4 7.982732E+00 7.982616E+00 1.451547E-05 9.803727E-02 5 7.912356E+00 7.912348E+00 1.084769E-06 6.846836E-02 6 7.772725E+00 7.772723E+00 1.840425E-07 5.525844E-02 7R 7.562489E+00 7.562516E+00 -3.657057E-06 6.685141E-02 8R 7.575960E+00 7.575985E+00 -3.398793E-06 6.633586E-02 9 7.943342E+00 7.943305E+00 4.622315E-06 1.302273E-02 10R 7.829101E+00 7.829069E+00 4.019795E-06 1.883844E-02 11 7.925030E+00 7.925027E+00 4.211797E-07 9.176641E-03 12 7.889203E+00 7.889194E+00 1.148394E-06 8.753594E-03 13 7.907179E+00 7.907176E+00 3.015218E-07 3.031719E-03 14 7.924466E+00 7.924470E+00 -5.415548E-07 3.125000E-06 15 7.924493E+00 7.924493E+00 0.000000E+00 -1.562500E-07


164

Support of Analysis Model Value Overriding Design Model Value

IntroductionIn SOL 200, when the value of an analysis model property is different from a design model value obtained by the relation defined on a DVxREL1 entry, the design model value overrides the analysis model value. The new PVAL option provides an alternate to allow the analysis model value to take the precedence over the design model value.

BenefitsProvides a flexible way for a sizing optimization job to start with either design model values or analysis model values.

InputThe PVAL option is applicable to three linear design property entries: DVPREL1, DVCREL1 and DVMREL1. To activate this option, specify the character input of “PVAL” on the COEF1 field on a DVPREL1 (DVCREL1, DVMREL1) entry.

OutputNone.

ExampleThe example shows designing a plate thickness. The plate thickness, 2.5, is defined on PSHELL 1 entry. First, the design entries without the PVAL option are given below. In this case, the design model value, 2.0 (the product of the initial design variable value, 1.0 and the coefficient, 2.0 on the DVPREL1 entry) will override the analysis model value. The comparison of analysis model value and design model value printed in the f06 file is shown here:

PSHELL 1 2 2.5DESVAR 1 THICK 1. 0.1 10.DVPREL1 1 PSHELL 1 T

1 2.0


Then, the DVPREL1 entry with the PVAL option is shown here with other two entries being kept the same. In this case, the design model value equals the analysis model property value, 2.5 obtained directly

from the 4th field of PSHELL 1 entry. The similar comparison of analysis model value and design model value is printed in the f06 file.

DVPREL1 1 PSHELL 1 T1 PVAL

Guidelines and Limitations1. The PVAL option only applies to the linear design property entries and is not applicable to

DVxREL2 entries.

2. When the PVAL option is used, only a single design variable can be referenced on a DVxREL1 entry and PVAL is applied to the COEF1 field. If a DVxREL1 entry references more than one design variable with the PVAL option, a user fatal error message will be issued.

----- COMPARISON BETWEEN INPUT PROPERTY VALUES FROM ANALYSIS AND DESIGN MODELS -----

------------------------------------------------------------------------------------------------------------------------------------------------------------ PROPERTY PROPERTY PROPERTY ANALYSIS DESIGN LOWER UPPER DIFFERENCE SPAWNING TYPE ID NAME VALUE VALUE BOUND BOUND FLAG FLAG ------------------------------------------------------------------------------------------------------------------------------------------------------------ PSHELL 1 T 2.500000E+00 2.000000E+00 N/A N/A WARNING

----- COMPARISON BETWEEN INPUT PROPERTY VALUES FROM ANALYSIS AND DESIGN MODELS -----

------------------------------------------------------------------------------------------------------------------------------------------------------------ PROPERTY PROPERTY PROPERTY ANALYSIS DESIGN LOWER UPPER DIFFERENCE SPAWNING TYPE ID NAME VALUE VALUE BOUND BOUND FLAG FLAG ------------------------------------------------------------------------------------------------------------------------------------------------------------ PSHELL 1 T 2.500000E+00 2.500000E+00 N/A N/A NONE


166


Ch. :

8 Miscellaneous Enhancements

! Export of Static Loads, 168

! Enhanced Participation Factor Results, 171

! Total Strain Energy Output for Defined SETs, 183

! Model Checkout Procedures - Method to Vary Material Properties, 186


168

Export of Static Loads

Introduction Functionality was added to MSC.Nastran to facilitate load transfer from one run to the next in three important ways:

1. MSC.Nastran can use Grid Point Force methodology to extract the load on a user defined free body. This load is output on a PG-like matrix that has an associated NAME, ID and optional label. A BGPDT data block is also produced that contains information on the grids associated with the free-body.

2. MSC.Nastran can export static loads from a load case defined in the current subcase.

3. MSC.Nastran can now import a load from a pre-defined database (including, but not limited to, loads produced using the previous steps) to be used in the formation of the load on a structure.

BenefitsThe design of complex structures frequently involves joint development with a system integrator and a number of subcontractors. The development of design loads is typically the task of the system integrator based on an analysis of the entire vehicle. It is then necessary to communicate the loads on the pieces of the structure to various subcontractors. The ability to extract the load on a free body is particularly useful in aeroelasticity, where the load can be a combination of applied, rigid aerodynamic and inertial loadings. The ability to export the statically applied load, or some portion of the load, is felt to be of benefit when it is desired to apply the same loading to different representations of the same structure.

InputThe ability to export a statically applied load is enabled by the new EXPORTLD Case Control command as described in the MSC.Nastran 2005 Quick Reference Guide. Typically, this is applied at the subcase level, but can be applied above the subcase level as well. In any case, the command results in a unique load vector (qualified by LOADID and LOADNAME) for each subcase. If a subset of grids is provided by identifying a SET Case Control command as part of the EXPORTLD command, only the loads on the grids associated with this grid are exported. A BGPDT (Basic Grid Point Data Table) is output with the load vector to identify the degrees of freedom associated with each of the rows in the vector.

The ability to export a free body load is done through the combination of the new FBODYLD Case Control command and the FBODYLD and FBODYSB Bulk Data entries. The FBODYLD Case Control command is used to point to the FBODYLD Bulk Data (via the NAMEi called out on the case control command) that defines the submodel for which the freebody load will be calculated and stored. The case control command also provides an optional load ID that can be associated with the load. The FBODYLD Bulk Data entry, in turn, points to a FBODYSB Bulk Data entry. The FBODYLD entry provides a label that is intended to identify the loading condition while the FBODYSB entry has a second label that is intended to identify the component. Both labels are optional. The FBODYSB entry identifies the grids

169CHAPTER 8Miscellaneous Enhancements

and elements that make up the free body and provides the ability to exclude certain types of grid point forces in creating the free body load.

The remarks for the EXPORTLD Case Control command indicate how the loads created with an EXPORTLD request can be used in a subsequent run using FMS statements such as:

ASSIGN loads1=’run1.MASTER’DBLOCATE datablk=(EXTLD,EXTBGP) WHERE(LOADNAME=’ALLCASES’), CONVERT(LOADID=LOADID+1000) LOGICAL=loads1…CENDLOADS=1001 $ Select external load with LOADID=1001, imported from previous run.

The EXTLD datablock contains the loads whereas the EXTBGP contains the grid point information that is used to match up the imported loads with the grid points. Clearly, it is necessary that the Grid ID’s have the same meaning in the two runs.

The import of a load created using the FBODYLD Case Control command is similar except it is now necessary to rename the datablocks created in the previous run to match those required for the import of these loads:

ASSIGN loads1=’fbrun1.MASTER’DBLOCATE datablk=(FBLPG/EXTLD,FBLBGPDT/EXTBGP) WHERE(LOADNAME=’fblcase’), CONVERT(LOADID=LOADID+1000) LOGICAL=loads1…CENDLOADS=1001 $ Select external load with LOADID=1001, imported from previous run.

OutputThe new commands produce limited output. The FBODYLD request does produce informational messages from a DBDICT statement that requests output on the presence of all FBLPG and FBLBGPDT data blocks along with qualifiers as to loadid, namei (from case control and the FBODYLD Bulk Data entry), submodel name from the FBODYSB entry and the labels from the two bulk data entries.

Examples (TPL: exptld/imptld, sysmod/fbody, sfsw/ffsw) There are three simple sets of test cases in the text problem library that demonstrate these new features, each with an export import pair. Exptld.dat exports the load applied to the center section of a flat plate while imptld.dat applies this load to a model of only the center section of the plate. In this case, it is not necessary to dblocate the EXBGP datablock because the exported load is perfectly aligned with the reduced model. However, this is not a good practice in general.

Sysmod.dat is a SOL 101 run that creates a free body load on center section of the same small plate model used in the previous example. Note that the applied loads are excluded using an input of “A” on the XFLAG field of the FBODYSB Bulk Data entry. Only the element forces are used to create the load,


170

which is in equilibrium across the cutout. The fbody.dat file imports this load onto a model that is only the center section of the original model. It is necessary to constrain a corner of this “free body” to remove the rigid body motion. An examination of the .f06 results for this run shows that the SPC forces are negligible while the stresses agree well for the elements that are shared between the two models. The displacements do not agree, but this is to be expected because they displacements for the small model are relative to the artificially constrained model.

Sfsw.dat is a SOL 144 run that demonstrates the ability to ask for different free body loads is separate subcases and has multiple FBODYLD/FBODYSB pairs for different components of the familiar forward swept wing. The fuselage subsystem is selected for further analysis in the subsequent run and it is seen the FBODYSB entry with FUSELAGE in the NAMES field has the applied loads excluded using an ‘A’ in the XFLAG field. Ffsw.dat imports this load into a SOL 101 that only has a model of the fuselage and comparison of the results shows that the stresses in the bars that represent the fuselage agree well between the two runs.

Guidelines and LimitationsThe EXPORTLD command has utility in SOL 101. In SOL 144, only the applied loads are output with this command and these are typically zero.

The applied loads are typically excluded when using the FBODYSB Bulk Data entry so that only element forces remain at the grid points.

Import of loads has the following rules

• If a set of imported loads share a common LOADID value, then those loads will implicitly be added. The same holds true for imported loads and bulk data load sets that share a common ID.

• To explicitly combine load sets, the load IDs should be made unique. The LOAD Bulk Data entry can then be used to explicitly define the linear combination.

• Both standard exported loads (EXPORTLD) and free body loads (FBODYLD) can be imported and used together in a single run. It is up to the user to keep the load IDs unique between them.

• The BGPDT is used to link the exported loads to the grids points of the model to which they are applied. This means that the grid id’s for the loaded grids must be the same in the two models.


Enhanced Participation Factor Results

IntroductionNew Case Control commands PFMODE, PFPANEL and PFGRID have been implemented to request modal, panel and grid participation factors. These commands will replace the existing FLSPOUT and MCFRACTION Case Control commands.

A new, consistent output format is used for all types of modal and panel participation factors. This format is similar to the output format obtained with the MCFRACTION command. The output format of grid participation factors is similar to the output format of displacements.

In addition, the new implementation supports

• panel definition by referencing a set of grids, a set of elements or a set of properties.

• panel and grid participation factors in direct frequency response analysis (SOL 108).

Finally, an adjoint method is used to compute acoustic structural modal participation factors, acoustic panel participation factors and acoustic grid participation factors, resulting in significant performance improvements.

Benefits• The new case control commands and the new output formats provide a consistent user interface

to all kinds of participation factors that is easy to use.

• The following example shows significant reductions of computation times and IO when computing panel participation factors:

Problem Data Performance Data

3.3 mio. Structural Degrees of Freedom25000 Fluid Degrees of Freedom1022 Structural Modes45 Fluid Modes85 Subcases

Panel participation factors have been computed for 2 fluid grid points and 9 panels.

2005 r2 2005 r3

Elapsed Time (s) 22020 3960CPU Time (s) 9027 1332IO (GB) 24426 6415

These data refer to the computation of the participation factors only.


172

TheoryIn a linear structural dynamic analysis, the results at a degree of freedom considered are the sum of the contributions of the different modes, e.g., the accelerations at a degree of freedom considered are the sum of the accelerations due to the responses of the different structural modes. These contributions are called structural modal participation factors or modal contribution fractions. The degrees of freedom considered are called response degrees of freedom. Structural modal participation factors allow to identify the structural modes that have the largest influence on the response.

Likewise, in an acoustic analysis, the pressure at a grid point considered is the sum of the pressures due to the responses of the different fluid modes. These contributions are called acoustic fluid modal participation factors. Acoustic fluid modal participation factors allow to identify the fluid modes that have the largest influence on the response.

In a coupled analysis, the pressure at a response degree of freedom is the sum of the pressure due to the acoustic sources in a rigid cavity, and the pressure due to the acceleration of the fluid-structure interface, the so-called wetted surface. The pressure due to the acoustic sources in a rigid cavity is called the load participation factor.

The acceleration of the fluid-structure interface is the sum of the accelerations due to the responses of the different structural modes, obtained from a coupled analysis. These contributions are called acoustic structural modal participation factors. One acoustic structural modal participation factor equals the


pressure at the response degree of freedom if there are no acoustic sources, and if the acceleration of the wetted surface consists of the response of one mode only. Thus, the acoustic structural modal participation factors allow to identify the structural modes that have the largest influence on the pressure at the grid point considered. In the absence of acoustic sources within the cavity, the acoustic structural modal participation factors sum up to the total pressure at the response degree of freedom.

Modal participation factors, by their nature, are useful only in the low-frequency range where the resonance frequencies are well separated, and the response is dominated by a small number of modes. On the contrary, geometric participation factors are useful also at higher frequencies where the response has contributions from a large number of modes. There are two types of geometric participation factors, namely panel participation factors and grid participation factors.

A panel is a set of grid points of the wetted surface. The panel participation factor is that pressure at the grid point considered that results from the accelerations of the grid points of the panel only, with all other grid points of the wetted surface kept fixed. Thus, panel participation factors allow to identify the regions of the wetted surface that have the largest influence on the acoustic pressure at the grid point considered. Panel participation factors usually do not sum up to the total acoustic pressure. This is only the case if the panels do not overlap, and if their union equals the complete wetted surface.

The accelerations of the grid points of the panel are the sum of the accelerations due to the different structural modes. The pressure due to the accelerations at the grid points of the panel that are due to one mode only is called the acoustic panel modal participation factor. Acoustic panel modal participation factors sum up to the panel participation factors.

Finally, if the panels consist of one grid point only, acoustic grid participation factors are obtained. For each structural grid point of the wetted surface, there are six acoustic grid participation factors, i.e. the pressures at the response degree of freedom due to the accelerations of the six degrees of freedom of this grid point. The acoustic grid participation factors depend on the mesh size. Thus, their absolute value has no physical meaning. However, if the mesh of the wetted surface is of comparable size everywhere, the acoustic grid participation factors allow to quickly identify the regions that make the largest contribution to the acoustic pressure at the grid point considered, and thus help to define the panels.

Participation factors are complex quantities, summing up to the complex response. Thus, if they are divided by the response, they sum up to one. The participation factors divided by the response are called normalized participation factors. Normalized participation factors are complex quantities, too.

The real parts of the normalized participation factors sum up to one whereas the imaginary parts sum up to zero. Thus, the real part of a normalized participation factor is that part of the participation factor that is in phase with the total response, divided by the magnitude of the total response. It is called the modal fraction. The phase of a normalized participation factor is the phase of the participation factor relative to the total response.

If the modal fraction is multiplied by the magnitude of the total response, the projected participation factor is obtained. It is that part of the participation factor that is in phase with the total response. The projected participation factors sum up to the total magnitude.


174

InputComputation and output of modal participation factors is controlled by the PFMODE Case Control command:

ExampleSET 20 = 25/T3, 33/T3PFMODE(STRUCTURE, STRUCTMP=ALL) = 20

Compute structural modal participation factors for z-translations at grid points 25 and 33

SET 20 = 11217SET 90 = 25., 30., 35.PFMODE(FLUID, STRUCTMP=ALL, FLUIDMP=ALL, SOLUTION = 90) = 20

Compute acoustic structural and fluid modal participation factors for pressure at grid point 11217 at excitation frequencies 25Hz, 30Hz and 35Hz.

Computation and output of panel participation factors is controlled by the PFPANEL Case Control command:

PFMODE STRUCTURE

FLUID

PRINT, PUNCH

PLOT

REAL or IMAG

PHASE , , ,

SORT sorttype=[ ] KEY sortitem=[ ] ITEMSALL

itemlist( )

= , , ,

FLUIDMP

ALL

mf

NONE

= STRUCTMP

ALL

ms

NONE

= , ,

PANELMP

ALL

setp

NONE

= SOLUTION

ALL

setf

NONE

= FILTER fratio=[ ], ,

NULL ipower=[ ] )setdof

NONE

=

,


ExampleSET 100 = 10., 12.SET 200 = 1222, 1223PFPANEL(SOLUTION=100, SORT=ABSD) = 200

Compute acoustic panel participation factors for pressure at grid points 1222 and 1223 at excitation frequencies 10Hz and 12Hz. Output is sorted according to descending modal fractions.

Computation and output of grid participation factors is controlled by the PFGRID Case Control command:

ExampleSET 20 = 11217SET 90 = 25., 30., 35.PFGRID(SOLUTION = 90) = 20

Compute acoustic grid participation factors for the pressure at grid point 11217 at excitation frequencies 25Hz, 30Hz and 35Hz.

Detailed descriptions of the PFMODE, PFPANEL and PFGRID Case Control Commands can be found in the Quick Reference Guide.

Panels are defined in the Bulk Data Section using PANEL Bulk Data entries which reference SET1 or SET3 Bulk Data entries.

PFPANEL PRINT, PUNCH

PLOT

REAL or IMAG

PHASEPANEL

ALLsetp-----------

= , , ,

SORT sorttype=[ ] KEY sortitem=[ ] ITEMS ALL

itemlist( )

= , , ,

SOLUTIONALL

setf

NONE

= FILTER fratio=[ ] NULL ipower=[ ], ,

setdof

NONE

=

PFGRID PRINT, PUNCH

PLOT

REAL or IMAG

PHASEGRIDS

ALL

setg

=, ,

SOLUTION

ALL

setf

NONE

=

setdof

NONE

=


176

• SET1 Bulk Data entries list the grid points of the panels.

• SET3 Bulk Data entries with option ELEM list the elements of the panels. The panels consist of all grid points associated to these elements.

• SET3 Bulk Data entries with option PROP list the property identifiers of the elements of the panels. The panels consist of all grid points associated to the elements with the property identifiers defined.

Output

Output can be printed to the .f06 file, written to the .pch file or the .op2 file or stored in the database for later access by SimOffice.

Three different formats are used for printed output to the .f06 files. The format for modal participation factors is similar to the format obtained with the MCFRACTION command. The header contains the type of the participation factor, information on the grid point and degree of freedom considered, the total response, information on excitation frequency, subcase and load and information on the maximum modal response, the sort method and the filter. In case of acoustic panel modal participation factors, the header contains the name of the panel considered and the panel response instead of the total response.

The data are presented in ten columns:

The format for acoustic panel participation factors is the same as for modal participation factors, except that the first two columns contain the panel names.

Load participation factors are included in the acoustic structural modal participation factors and the acoustic panel participation factors, with a mode number of 0 and a panel name –LOAD-. Acoustic structural modal participation factors, together with the load participation factor, sum up to the total response.

Column Label Description

1 Mode Id Mode number

2 Natural Freq (Hz) Resonance frequency

3-4 Modal Response: Real / Imaginary Real and imaginary part of participation factor

5-6 Modal Response: Magnitude / Phase Magnitude and phase of participation factor

7 Projection Magnitude Projected participation factor: That part of the participation factor that is in phase with the total response

8 Relative Phase Phase of participation factor relative to total response

9 Modal Fraction Real part of normalized participation factor

10 Scaled Response Magnitude Projected participation factor divided by largest magnitude of all participation factors


Acoustic grid participation factors use the output format of complex displacements. Both real and imaginary part or magnitude and phase format are available. There is one output per excitation frequency and fluid grid point.

Example

The numbers printed indicate the normalized acoustic pressure at the selected grid point due to the accelerations at the corresponding degrees of freedom.

GuidelinesThe amount of output produced may be very large. This is especially true for acoustic panel mode participation factors and for acoustic grid participation factors (e.g., the number of data produced for acoustic panel modal participation factors equals the number of subcases times the number of excitation frequencies times the number of response degrees of freedom times the number of panels times the number of structural modes). Consequently, output should be limited to a small number of excitation frequencies and to a small number of response degrees of freedom.

LimitationsIn the current version, acoustic participation factors are not computed correctly in case of direct enforced motion.


178

Example--Acoustic Analysis of a CabinThe example shows the acoustic analysis of a cabin. The cabin is excited by four forces at the corners of the seat. The result of interest is the pressure at the driver’s ear.

The frequency response of the pressure shows a peak at 37Hz. To investigate this peak, acoustic fluid and structure modal participation factors and panel participation factors are requested at a frequency of 37Hz.

Panels are defined for the front window, the rear wall, the left and the right side, the top and the bottom.

Input Data

$ Participation Factor Test Problem: Cabin$$ Coupled Modal Frequency Response Analysis$$ Participation Factor Example - Cabin$$ Illustrates use of$ o Acoustic Fluid Modal Participation Factors$ o Acoustic Struct. Modal Part. Factors$ o Acoustic Panel Part. Factors$ o Acoustic Grid Part. Factors $$ =======================================================


$SOL 111 DIAG 8 CEND$ECHO=SORT(EXCEPT,CBEAM,CQUAD4,CHEXA,CPENTA,GRID)AUTOSPC(NOZERO) = YES$METHOD(STRUCTURE)=1 METHOD(FLUID) =2 $FREQ = 100DLOAD = 200 $SET 1 = 11217 SET 20 = 11217SET 90 = 37.$DISP(PHAS) = 1$PFMODE(FLUID, STRUCTMP=ALL, FLUIDMP=ALL, SOLUTION=90, SORT=ABSD) = 20PFPANEL(SOLUTION=90, SORT=ABSD) = 20$OUTPUT(XYPLOT) XPAPER=29.


180

YPAPER=21. XGRID=YES YGRID=YES XTITLE = Frequency YTITLE = Pressure XYPLOT DISP RESPONSE / 11217(T1)$BEGIN BULK$$ Request OP2 for PATRANPARAM, POST, -1 $$ Define Structural DampingPARAM, G, 0.02 $$ Define Fluid DampingPARAM, GFL, 0.002 $$ Define Reference Pressure for dB (in Pa)PARAM, PREFDB, 2.8284-5 $PARAM, GRDPNT, 0 $ Request Weight Output$$ Structural and Acoustic Modes up to 300HzEIGRL, 1,,300. EIGRL, 2,,300. $$ Frequency Range: 25Hz to 100Hz by Steps of 5HzFREQ1, 100, 25., 5., 15$ Additional Frequencies around Resonance FrequenciesFREQ4, 100, 25., 100., 0.01, 5$$ Excitation ForcesRLOAD1, 200, 210,,, 220DAREA, 210, 1, 3, 1., 7, 3, 1.DAREA, 210, 29, 3, 1., 35, 3, 1.TABLED1, 220 , 0., 1., 1000., 1., ENDT$$ Nonmatching Fluid-Structure InterfaceACMODL, DIFF $$ Include Structural and Acoustic ModelINCLUDE 'cabin_structure.bdf'INCLUDE 'cabin_fluid.bdf'$$ Panels$SET3, 101, ELEM, 127, THRU, 162, 667, THRU, 738SET3, 201, ELEM, 37, THRU, 72, 739, THRU, 810SET3, 301, ELEM, 331, THRU, 384SET3, 401, ELEM, 25, THRU, 36, 73, THRU, 126SET3, 501, ELEM, 271, THRU, 294, 601, THRU, 612SET3, 601, ELEM, 1, THRU, 24, 455, THRU, 478,


, 497, THRU, 562$PANEL, LEFT, 101, RIGHT , 201, FRONT, 301, REAR, 401PANEL, TOP , 501, BOTTOM, 601$ENDDATA

Acoustic Structural Mode Participation Factors:


182

Acoustic Panel Participation Factors:

The acoustic structural mode participation factors show that the largest contribution comes from the 7th structural mode which has a resonance at 37.2Hz. The acoustic panel participation factors show that the rear wall and the bottom make the largest positive contribution whereas all remaining panels make negative contributions.


Total Strain Energy Output for Defined SETs

IntroductionTotal Strain Energy output can now be requested for user defined element SETs.

InputsA new Case Control command, SETP described below is introduced for defining the list of element SETs, which are referenced by the ESE – Element Strain Energy Output request.

Process Sets are used to define lists of SET identifications to be processed individually for data recovery:

Formats

SETP n = i1[,i2,i3 THRU i4 EXCEPT i5,i6,i7,i8 THRU i9]

Examples

SET 77=5SET 88=5, 6, 7, 8, 9, 10 THRU 55

Remarks:1. A SETP command may be more than one physical command. A comma at the end of a physical

command signifies a continuation command. Commas may not end a set. THRU may not be used for continuation. Place a number after the THRU.

2. Set identification numbers following EXCEPT within the range of the THRU must be in ascending order.

In SET 88 above, the numbers 77, 78, etc., are included in the set because they are outside the prior THRU range.

SETP Process Set Definition

Describer Meaning

n SETP identification number. Any SETP may be redefined by reassigning its identification number. SETPs specified under a SUBCASE command are recognized for that SUBCASE only. (Integer > 0)

SET Identification numbers. If no such identification number exists, the request is ignored. (Integer > 0)

EXCEPT Set identification numbers following EXCEPT will be deleted from output list as long as they are in the range of the set defined by the immediately preceding THRU. An EXCEPT list may not include a THRU list or ALL.


184

3. SETP usage is limited to the EDE, EKE, and ESE Case Control Commands.

Example

A small example (see setp01.dat in the examples folder) is shown below to show usage of the SETP command. Note only essential entries are shown.

id msc, setp $ TIME 6SOL 101CENDSPC=1setp 100 = 1 thru 43set 1 = 1set 2 = 2set 3 = 3set 4 = 4set 5 = 5set 6 = 6set 7 = 7set 8 = 8set 9 = 9..SUBCASE 1001LOAD=101ese = 100SUBCASE 1002LOAD=102ese = 100BEGIN BULKCQUAD4 1 1 1 2 9 8 CQUAD4 2 1 2 3 10 9 CQUAD4 3 1 3 4 11 10 CQUAD4 4 1 4 5 12 11 CQUAD4 5 1 5 6 13 12 CQUAD4 6 1 6 7 14 13 CQUAD4 7 1 8 9 16 15 CQUAD4 8 1 9 10 17 16 CQUAD4 9 1 10 11 18 17 ..ENDDATA


Output Example

An excerpt of the element strain energy output for the example is shown below:0 SUBCASE 1001 E L E M E N T S T R A I N E N E R G I E S ELEMENT-TYPE = QUAD4 * TOTAL ENERGY OF ALL ELEMENTS IN PROBLEM = 4.593646E+00 SUBCASE 1001 * TOTAL ENERGY OF ALL ELEMENTS IN SET 1 = 2.973878E-030 ELEMENT-ID STRAIN-ENERGY PERCENT OF TOTAL STRAIN-ENERGY-DENSITY 1 2.973878E-03 0.0647 1.631036E+00

TYPE = QUAD4 SUBTOTAL 2.973878E-03 0.0647 0 SUBCASE 1001 E L E M E N T S T R A I N E N E R G I E S ELEMENT-TYPE = QUAD4 * TOTAL ENERGY OF ALL ELEMENTS IN PROBLEM = 4.593646E+00 SUBCASE 1001 * TOTAL ENERGY OF ALL ELEMENTS IN SET 2 = 1.778719E-030 ELEMENT-ID STRAIN-ENERGY PERCENT OF TOTAL STRAIN-ENERGY-DENSITY 2 1.778719E-03 0.0387 5.811762E-01

TYPE = QUAD4 SUBTOTAL 1.778719E-03 0.0387


186

Model Checkout Procedures - Method to Vary Material Properties

IntroductionA new feature has been introduced that provides users with a simple means to evaluate the mass and thermal load characteristics of a structure. The feature is intended primarily for linear static analysis runs that are being used to validate aspects of the finite element model prior to embarking on more expensive production static and dynamics analyses. It allows the user to temporarily modify the material density and thermal expansion coefficient fields of material property bulk data entries. To implement the feature, the new MODEL_CHECK Executive Control statement and several NASTRAN Statement keywords have been introduced. Use of the feature causes the affected material property fields to be temporarily modified during the run. All results will be based on the temporary values of the material properties. The material property data stored on the Material Property Table data block is not modified and retains the original values supplied on the bulk data entries.

BenefitsThe introduction of this new feature simplifies the procedure typically used to evaluate the mass and thermal load characteristics of a finite element model. This procedure usually involves preparation, usage and storage of a duplicate set of bulk data material property entries that have the material density and thermal expansion coefficient values set to the values desired for model checkout purposes. When the model is undergoing checkout procedures, the production set of bulk data material property entries is replaced by the alternate set of bulk data material property entries. Creating and switching between the two sets of data for production and checkout runs is tedious and prone to errors. The material property update options of the MODEL_CHECK statement improve user productivity by reducing the need to create, maintain and substitute different sets of material properties needed for model check purposes.

Method and TheoryThere is no additional theory introduced by this feature. Finite element matrix generation and stress recovery operations use material properties in exactly the same manner as without this feature. The only difference is the actual value of the material property itself. The method is equally simple. As material property data is referenced, a check is made to see whether MODEL_CHECK is active for temporary material property updates. If it is, the appropriate entry of the material property data (mass density and/or thermal expansion coefficient(s)) is set to the user-specified value. All subsequent computations use the updated value.

InputsThis feature is activated using the new MODEL_CHECK Executive Control statement. The MODEL_CHECK statement features keywords that allow a value to be temporarily assigned to the


material density and thermal expansion coefficients. The general format of the statement used to change material properties to a specified value is:

MODEL_CHECK [ MAT_DENSITY=value, ] [ MAT_TECO=value, ] [ MAT_TEIJ=value ]

The complete description of the MODEL_CHECK statement can be found in Executive Control Statement Descriptions (p. 108) in the MSC.Nastran Quick Reference Guide.

OutputsThe MODEL_CHECK material property update feature produces no printed output other than an informational message summarizing the updates that will take place.

Guidelines and Limitations• MODEL_CHECK is ignored in RESTARTs

• Material property updates will take effect for all MAT1, MAT2, MAT3, MAT8 and MAT9 Bulk Data entries present in the input.

• Material properties stored on the Material Property Table (MPT) data block are those present on the bulk data material property entries.

• Post-processing of results could reference in-consistent data since the results are based upon different material property data than is present in the bulk data.

Demonstration ExampleA simple example is presented that demonstrates the material property update feature. The example consists of several disjoint models and is not intended to be representative of any production model. The MODEL_CHECK statement is used to temporarily set all material densities and thermal expansion coefficients to 0.0. This results in model mass contributions from only the CONM2 element and the non-structural mass as well as results for the temperature load case (subcase 3) being null.

Example Input Data$$***********************************************************************$$VERSION: 2004+$TEST DECK NAME: varmat01a.dat (Baseline Model w/MODEL_CHECK)$ Density is not temperature dependent.$ Thermal expansion coefficient is not temp. dependent$ MODEL_CHECK command present.$$PURPOSE:$ Demonstrate usage of the new MODEL_CHECK Executive Control Statement$ Note that non-structural mass cannot be modified using this command.$$DESCRIPTION:


188

$ The model consists of$ 1) CONM2 eid 3001 contributing mass.$ 2) ROD eid 101 referencing MAT1 materials$ 3) QUAD4 eid 3301 w/ PSHELL referencing MAT1 materials$ 4) QUAD4 eid 3313 w/ PSHELL referencing MAT1 and MAT2 materials$ 5) QUAD4 eid 3321 w/ PCOMP referencing MAT8 materials$ 6) HEXA eid 6701 w/ PSOLID referencing MAT9 materials$ 7) TRIAX6 id 5301 referencing MAT3 materials$$ A MODEL_CHECK executive command is used to modify material property$ data temporarily during the run. The command demonstrates$ 1) setting the material density to 0.0 via the OFF option$ 2) setting the material thermal expansion coefficients to 0.0 via$ the OFF option$ 3) continuation of MODEL_CHECK command$$EXPECTED RESULTS:$ 1) There should be an informational message indicating which of the$ material property data is being modified.$ 2) The grid point weight generator and element summary outputs should$ indicate mass for only the conm2 element and the non-structural$ masses of the rods and plates$ 3) results output for subcase 3 (temperature loading) should be 0.0$ since MODEL_CHECK is setting the alphas=0.0$ID MSC, varmatTIME 30 $SOL 101$$========================================================================$ temporarily set the density and thermal expansion coefficients for all$ materials to 0.0$model_check mat_density=off, mat_tecoeff=off,mat_teij=off$$========================================================================$CENDTITLE= VARIABLE MATERIAL TEST CASESUBTITLE = MSC V2005ECHO = SORTSPC = 12TEMP(MATE) = 1 SET 10002= 1 THRU 13999, 14399 THRU 16900 DISP=ALL ELFORCE=ALL OLOAD = ALL$ SPCF=ALL ESE=10002 SEFINAL=1 GPFO=10002$ELSUM(EID,PRINT) = ALL$SUBCASE 1LABEL = STATIC LOAD LOAD = 1 P2G=MATLOAD K2GG=MATK


SUBCASE 3LABEL = TURN ON TEMP LOADS TEMP(LOAD) = 2$BEGIN BULK$$ C O M M O N D A T A T O A L L P R O B L E M SPARAM, SNORM, 0.$CORD2C 1 0 3.0 -1.0 0.0 9.0 -1.0 0.0 +CORD2C+CORD2C 9.0 0.0 -1.0$CORD2R 2 0 0.0 -2.0 0.0 1.011234-2.0 0.0 +CORD2R+CORD2R 0.0 0.0 0.0$CORD2S 3 1 3.0 225.0 0.0 3.0 225.0 1.234567+CORD2S+CORD2S 3.0 -45.0 3.0$GRAV 3 1.0 1.0 1.0 1.0TEMPD 1 100.0TEMPD 2 200.0$MAT1 1 1. .8 .1 .05 .001 100. .01 +MAT11+MAT11 2.0 3.0 4.0MATT1 1 2 +MATT1+MATT1 4 5 6$MAT1 2 1.0E+7 0.3 .05 .001 100.0 .01 +MAT1-2+MAT1-2 1000. 2000. 3000.MATT1 2 +MATT1-2+MATT1-2 2 2$MAT2 22 1.0E+7 0.5E+6 0.5E+6 1.0E+7 0.5E+6 1.0E+7 .022 +MAT221+MAT221 .01 .02 .025 100.0 0.035MATT2 22 +MATT221+MATT221$MAT3 33 1.0E+7 1.0E+7 1.0E+7 .33 .33 .33 .00259 +MAT331+MAT331 2.4E+6 .001 .001 .001 100. .025MATT3 33 +MATT331+MATT331 $MAT8 3 1.E+7 1.E+7 .25 4.E+6 4.E+6 4.E+6 1.0 +MAT81+MAT81 1.-6 2.-6 1.E-4 1.E-3 1.E-4 +MAT82+MAT82 1.0$MAT9 9 1.E+7 1.E+7 +MAT91+MAT91 1.E+7 +MAT92+MAT92 5.1+3 5.1+3 5.1+3 .05 .001 +MAT93+MAT93 .002 .003 .004 .005 .006 100.0 .008MATT9 9 +MATT91+MATT91 +MATT92+MATT92 +MATT93+MATT93$TABLEM1 2 +TABLE-2+TABLE-2 0.0 1.0 150.0 1.0 150. 0.5 300. 0.5 +TABL-2+TABL-2 ENDT ENDTTABLEM2 3 100.0 +TABLE-3+TABLE-3 0.0 0.1 50.0 0.1 50.0 0.5 150.0 0.5 +TABL-3


190

+TABL-3 200.0 10.0 ENDTTABLEM3 4 100.0 2.0 +TABLE-4+TABLE-4 0.0 0.1 25.0 .1 25.0 2.0 75.0 2.0 +TABL-4+TABL-4 300.0 .00001 ENDTTABLEM4 5 100.0 100. 2.0 10.00 +TABLE-5+TABLE-5 2.0 ENDTTABLEM4 6 0.0 100. 0.0 100.00 +TABLE-6+TABLE-6 1.0 .25 ENDTTABLEM1 91 +TAB912+TAB911 0.0 0.01 150.0 0.05 150. 0.1 300. 0.2 +TAB912+TAB912 ENDTTABLEM1 92 +TAB921+TAB921 0.0 0.001 150.0 0.002 150. 0.003 300. 0.006 +TAB922+TAB922 ENDTTABLEM1 93 +TAB931+TAB931 0.0 1.0 150.0 1.0 150. 0.08 300. 0.1 +TAB932+TAB932 ENDT$PARAM, GRDPNT 0PARAM, NT 1PARAM, TINY 0.PARAM, AUTOSPC,YESPARAM, COMPARE,1 $ PROCESS SELECTED S.E., THEN ENTIRE MODEL, DMAP0PARAM, PNCHDB, 1 $ PUNCH FROM DATA BASE, DMAP0PARAM, NOELOP, 1 $ SUM OF FORCES. MG 21 OCT 1980$PARAM, NOGPF, -1 $ SUPPRESS GPFO OUTPUT. LOOK AT ELOP INSTEAD. MG$$ SPCS TO BE SELECTED FOR RF 1 THRU 12SPCADD 12 1 2$ SPCS TO BE SELECTED FOR RF 51,53 AND 59SPCADD 13 1 3$FREQ1 10 0.0 1.0 1RLOAD2 11 12 14TABLED1 14 +TABD4.1+TABD4.1-1.0 1.0001 2.0 1.0001 ENDT$$ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++$$ ROD ELEMENT NO. 1$CROD 101 101 101 102GRID 101 0 0.0 0.0 0.0GRID 102 0 1.0 0.0 0.0SPC1 1 123456 101SPC1 1 2356 102FORCE1 1 102 1.0 101 102MOMENT1 1 102 1.0 101 102DAREA 12 102 1 1.0 102 4 1.0PROD 101 1 1.0 2.0 0.1 0.5$$$+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++$$ QUAD4 ELEMENT NO. 33$CQUAD4 3301 3301 3301 3302 3303 3304 0.


GRID 3301 0 0.0 0.0 0.0GRID 3302 0 1.0 0.0 0.0GRID 3303 0 1.0 1.0 0.0GRID 3304 0 0.0 1.0 0.0SPC1 1 1256 3302 3303SPC1 1 123456 3301 3304FORCE 1 3302 0 1.0 0.0 0.0 1.0FORCE 1 3303 0 1.0 0.0 0.0 1.0DAREA 12 3302 3 1.0 3303 3 1.0PSHELL 3301 1 1.0 1 120.0 1 1.0 0.5 +QUAD41+QUAD41 0.2 -0.3$CQUAD4 3313 3313 3313 3314 3315 3316 382.5 +QUAD42+QUAD42 .63 .67 .53GRID 3313 3 3.0 90. 0. 3 123456GRID 3314 3 3.0 90. 60. 2 123456GRID 3315 3 3.0 40. 60. 1 4GRID 3316 3 3.0 30. 0. 0 5FORCE 1 3315 2 3.14159 0. 2.71828 0.DAREA 12 3315 3 1.73205PSHELL 3313 22 .618034 2 1 .30103 +QUAD43+QUAD43 0.$$ COMPOSITE TESTING , WITH STRAIN THEORY, ADDED 17JUN87, LNACQUAD4 3321 3321 3321 3322 3323 3324 0.GRID 3321 0 0.0 0.0 0.0 13456GRID 3322 0 10.0 0.0 6GRID 3323 0 10.0 10.0 0.0 6GRID 3324 0 0.0 10.0 0.0 123456FORCE 1 3322 0 1.+3 1.0 0.0 1.0FORCE 1 3323 0 1.+3 1.0 0.0 1.0DAREA 12 3322 3 1.0 3323 3 1.0PCOMP 3321 1. STRN +QUAD4C+QUAD4C 3 0.5 0. YES 3 0.5 0. YES$$+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++$$ HEXA ELEMENT NO.67$$CHEXA 6701 6701 6701 6702 6703 6704 6705 6706 +C6701+C6701 6707 6708GRID 6701 0 0.0 0.0 0. 0 456GRID 6702 0 0.0 .08 0. 0 456GRID 6703 0 0.0 .08 .1 0 456GRID 6704 0 0.0 0. .1 0 456GRID 6705 0 1.0 0. 0. 0 456GRID 6706 0 1.0 .08 0. 0 456GRID 6707 0 1.0 .08 .1 0 456GRID 6708 0 1.0 0. .1 0 456PSOLID 6701 9 0 2SPC1 1 123 6701 THRU 6704FORCE 1 6705 0 .25 0. 0. -1.FORCE 1 6706 0 .25 0. 0. -1.FORCE 1 6707 0 .25 0. 0. -1.FORCE 1 6708 0 .25 0. 0. -1.PLOAD4 1 6701 -125. 6701 6703$


192

$+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++$$ DUM1 ELEMENT NO. 53$$ADUM1,6,3,0,3,CTRIAX6 $CTRIAX6 5301 33 5301 5302 5303 5304 5305 5306 +TRIAX61+TRIAX6130.0GRID 5301 0 6.0 0.0 0.0 0 2456GRID 5302 0 6.0 0.0 2.0 0 2456GRID 5303 0 6.0 0.0 4.0 0 2456GRID 5304 0 4.238 0.0 3.0 0 2456GRID 5305 0 2.536 0.0 2.0 0 2456GRID 5306 0 4.238 0.0 1.0 0 2456SPC1 1 3 5302PLOADX 1 .0222139.03332095301 5302 5303$$+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++$$ CONM2 ELEMENT NO. 30$CONM2 3001 3001 0 1.0 1.0 1.0 1.0 +CONM21+CONM21 1.0 1.0 1.0 1.0 1.0 1.0GRID 3001 0 0.0 0.0 0.0SPC 1 3001 123456 0.0$$========================================================================$$ DMIG ELEMENT NO. 100$ NOTE:P.S. 3 ADDED 14-JAN-82GRID 10000GRID 10001 3DMIG MATK 0 6 2 0DMIG MATK 10000 3 10000 3 1.D6 + 10001 3 -1.D6DMIG MATK 10001 3 10001 3 1.D6DMIG MATLOAD 0 9 1 0DMIG* MATLOAD 1 +DMIG*DMIG 10000 3 1.DMIG* MATLOAD 2 +DMIG2*DMIG2 10000 3 0.$enddata

Example OutputThe printed output for the example problem consists of all of the output typically generated by a static analysis for the requests present in the case control section of the input and is not reproduced here. There is a small section of additional printed output generated in the Executive Control Echo region when the MODEL_CHECK material property options are used. The output summarizes the requested material property updates and is shown on the next several lines.


There is no other printed output generated that is peculiar to the material property update feature. All other output is typical printed output that is generated by the case control requests. For this example, the Grid Point Weight Generator output was requested via param,grdpnt,0 in the bulk data so that the mass of the structure could be verified as being produced by only the CONM2 element and the element non-structural mass.

$ MODEL_CHECK MAT_DENSITY=OFF, MAT_TECOEFF=OFF,MAT_TEIJ=OFF *************************************************************************************************************************************************************************************************************** ** THE PRESENCE OF THE MODEL_CHECK EXECUTIVE STATEMENT CAUSES THE FOLLOWING MATERIAL ** PROPERTY VALUES TO BE MODIFIED FOR EVERY MAT1, MAT2, MAT3, MAT8 AND MAT9 MATERIAL ** PROPERTY ENTRY PRESENT IN THE INPUT BULK DATA SECTION: ** MATERIAL DENSITY REVISED VALUE = 0.00000E+00 ** THERMAL EXP. DIRECT COEFF. REVISED VALUE = 0.00000E+00 ** THERMAL EXP. SHEAR COEFF. REVISED VALUE = 0.00000E+00 ** * **************************************************************************************************************************************************************************************************************


194


Ch. :

9 Upward Compatibility

! Summary of DMAP Module Changes from MSC.Nastran 2005 r2 to MSC.Nastran 2005 r3, 196


196

Summary of DMAP Module Changes from MSC.Nastran 2005 r2 to MSC.Nastran 2005 r3This section summarizes DMAP module changes from MSC.Nastran 2005 r2 to MSC.Nastran 2005 r3 which could affect your DMAP alters and solution sequences. This information is intended to help you convert your MSC.Nastran 2005 r2 DMAP alters and solution sequences to run in MSC.Nastran 2005 r3.

The format of the following modules have been modified in MSC.Nastran 2005 r3 such that the MSC.Nastran 2005 r2 format is not upward compatible with MSC.Nastran 2005 r3 and/or their behavior is not upward compatible. The changes are described in the next section.

BDRYINFO DOM9 ILMPGPF

The following is a list of existing modules with new features or fixes which have format changes in MSC.Nastran 2005 r3 but their MSC.Nastran 2005 r2 formats are considered upward compatible in MSC.Nastran 2005 r3. The changes are described in the next section.

ADAMSMNF AELOOP DOM12 DOPR1 DSAD DSAL GI

GYROLD IFP IFP9 INPUTT2 LAMX MAKMON MATPRN

MESSAGE MKSPLINE NLITER NLSOLV RESTART ROTOR ROTRDR1

ROTRDR2 SEP1X SOLVIT TABPT

The following is a list of new modules in MSC.Nastran 2005 r3. They are not documented here but will be documented in the MSC.Nastran 2005 r3 DMAP Programmer’s Guide.

ADAMSRBM AFPMP AIEMGA CAMPREP DYNCXPNT GPSTRPBX IFPBSH2

MONVEC3 NLHARM NLICLOOP PFCALC RESMOD ROTRUTL

DMAP Module ChangesThis section shows the changes for DMAP module instructions which were changed from MSC.Nastran 2005 r2 to MSC.Nastran 2005 r3. The module change descriptions are presented as differences with respect to the the MSC.Nastran 2005 DMAP Programmer’s Guide which is available on the "Combined Documentation 2005" CD. The change descriptions below includes the MSC.Nastran 2005 r3 format of the module with changes in bold text. Any new or changed data blocks and parameters are also described below the format.

197CHAPTER 9Upward Compatibility

Generate modal neutral files using the MSC.Adams/FLEX MNF toolkit.

Format:

Input Data Blocks:

Extracts a single record of Case Control and sets parameter values for the generation of aerodynamic matrices or the solution of aerostatic and divergence analyses.

Format:

Parameters:

ADAMSMNF Generate files for MSC.Adams

ADAMSMNF UNITS,BGPDT,GEOM2,GEOM4,CMBXPHG,MABXWGG,MXWAA,KXWAA, PXA,GPSETS,ELSET,OGS1,OGSTR1,OGPWGBW,CASECC,PCDB/ BAAEA,OGS1P,OGTR1P/M9I/QUALNAM/SEID/NOSE/LUSET/NOASET/MNFOUT/OUTGS1/ OUTGSTR1/MINVAR/PSETID/CCSET/PRECOL/WTMASS $

BAAEA Modal damping matrix.

OGS1P Table of grid point stresses due to preload.

OGSTR1P Table of grid point strains due to preload.

AELOOP Aerodynamic loop driver

AELOOP CASECC,EDT,CCPOS/CASEA,CCPOS1/S,N,NSKIP/S,N,LPFLG/S,N,MFLG/S,N,MACH/S,N,Q/S,N,AEQRATIO/S,N,AECONFIG/S,N,SYMXY/S,N,SYMXZ/CRTPOS/S,N,RCONFIG/MASSETID/S,N,AESOLN $

AESOLN Output-character-default=' '. Aerodynamic solution name extracted from CASECC at word positions 454 and 455.


198

Generate the geometry and connectivity information for an external superelement definition based on the ASETi and QSETi Bulk Data entries and requested by the EXTSEOUT Case Control command.

Format:

Output Data Block:

Parameters:

BDRYINFO Generates geometry and connectivity information

BDRYINFO CASECC,GEOM1,GEOM2,BGPDT,USET,BULK,BULKINDX/GEOM1EX,GEOM2EX,GEOM4EX,CASEEX/MTRXFLAG/DMIGSFIX $

CASEEX Table of Case Control modified to include displacement output requests for all boundary points and all points connected to PLOTEL elements.

MTRXFLAG Input-integer-no default. Bit pattern indicating existence of boundary matrices. Used by EXTSEOUT(DMIGPCH) option only.

Boundary Matrix Bit Position from Right

Stiffness 1

Mass 2

Viscous damping 3

Structural damping 4

Static loads 5

Acoustic coupling 6

DMIGSFIX Input-character-no default. DMIG matrix name suffix. Used by EXTSEOUT(DMIGPCH) option only.


Performs soft and hard convergence checks in design optimization.

Format:

Input Data Blocks:

Parameters:

DOM12 Performs soft and hard convergence checks in design optimization

DOM12 XINIT,XO,CVAL,PROPI*,PROPO*,OPTPRM,HIS, DESTAB,GEOM1N,COORDO,EDOM,MTRAK,EPT,GEOM2,MPT, EPTTAB*,DVPTAB*,XVALP,GEOM1P, R1TABRG,R1VALRG,RSP2RG,R2VALRG,PCOMPT,UBULK,TOPELE, PBRMSN,OBJTBG,CVALA,CVALP/HISADD,OPTNEW,DBCOPT,DESNEW/ DESCYCLE/OBJIN/OBJOUT/S,N,CNVFLG/CVTYP/OPTEXIT/ DESMAX/MDTRKFLG/DESPCH/DESPCH1/MODETRAK/EIGNFREQ/ DSAPRT/PROTYP/BADMESH/XYUNIT/FSDCYC/OBJAPPX/OBJINIT/ S,N,REJECT/ISHAPE/TREGION $

CVALA Table of approximate constraint values for trust region analysis.

CVALP Table of exact constraint values at previous design cycle for trust region analysis.

OBJAPPX Input-real-default=0.0. approximate objective value for trust region analysis.

MXLAGM Input-real-default=0.0. Maximum Lagrange multiplier for trust region analysis.

REJECT Input/output-logical-default=FALSE. Rejected design flag for trust region analysis.

TRUE: Design is rejected.

FALSE: Design is accepted.

ISHAPE Input-integer-default=0. Shape optimization for trust region analysis.

=0

<>0

TREGION Input-integer-default=0. Trust region analysis flag. Extracted from word position 60 in OPTPRMG.

=0

<>0


200

Examples:

1. Excerpt from subDMAP DESOPT following hard convergence:

DBVIEW XPREV=XINITDBVIEW PROPPV=PROPIDBVIEW HISPV=HIS

(WHERE DESITER=DESCYCLP) $(WHERE DESITER=DESCYCLP and dptype=*) $(WHERE DESITER=DESCYCLP) $

cvtyp=2 $ PARAML optprmg//'DTI'/1/60//S,N,TREGION $ if ( tregion=1 ) trustR = TRUE $ if ( trustR ) then $ if ( mxlagmx=0.0 ) then $ if ( descycle=1 ) objinit = objin*10. $ else $ objinit = 2.*mxlagmx $ endif $ mxlagmx=0.0 endif $ trustR REJECT=FALSE $ DOM12 XPREV, XINIT, CVALRG, PROPPV, PROPIF, OPTPRMG, HISPV, DESTAB,,,EDOM,MTRAK,EPT,GEOM2,MPT, EPTTABF,DVPTABF,,,,,,,PCOMPT,,TOPELE,PBRMSNX, OBJTBG,CVALAPX,CVALRGP/ HISADD,NEWPRM,,NEWDES/ DESCYCLE/OBJPV/OBJIN/S,N,CNVFLG/CVTYP/OPTEXIT// MDTRKFLG/DESPCH/DESPCH1/MODETRAK/EIGNFREQ/DSAPRT/ PROTYP///FSDCYC/OBJAPPX/OBJINIT/S,N,REJECT/0/ TREGION $ APPEND HISADD,/HISX/2 $ equivx HISX/HIS/-1 $

2. Excerpt from subDMAP DESOPT following soft convergence:

DBVIEW PROPIF =PROPIDBVIEW PROPOF =PROPODBVIEW EPTABF =EPTTABDBVIEW DVPTABF =DVPTAB

WHERE (DPTYPE=*) $(WHERE DPTYPE = *)WHERE (DPTYPE=*) $WHERE (DPTYPE=*) $

DOM12 XINIT,XO,CVALO,PROPIF,PROPOF,OPTPRMG,HIS,DESTAB, GEOM1N,COORDO,,,EPTN,GEOM2N,MPTN,EPTTABF,DVPTABF, ,,,,,,PCOMPT,,TOPELE,PBRMSN,OBJTBG,,/ HISADD,NEWPRM,,NEWDES/ DESCYCLE/OBJIN/OBJOUT/S,N,CNVFLG/CVTYP/OPTEXIT// MDTRKFLG/DESPCH/DESPCH1/MODETRAK/EIGNFREQ// PROTYP///FSDCYCf $ APPEND HISADD,/HISX/2 $ EQUIVX HISX/HIS/-1 $


Performs the approximate optimization problem using design variables, constraints, responses and sensitivity information.

Format:

Input Data Blocks:

3. Excerpt from subDMAP EXITOPT for termination:

DBVIEW PROPIF =PROPI WHERE (DPTYPE=*) $ DBVIEW PROPOF =PROPO (WHERE DPTYPE = *) DBVIEW EPTTABF =EPTTAB WHERE (DPTYPE=*) $ DBVIEW DVPTABF =DVPTAB WHERE (DPTYPE=*) $ IF ( ABS(OPTEXIT)>3 OR (OPTEXIT=0 AND (CNVFLG>0 OR DESCYCL1=DESMAX OR NUMDDV>0 OR DSPRINT OR DSUNFORM OR DSEXPORT OR MODETRAK>0 OR BADMESH)) ) DOM12 ,,XVAL,,,PROPOF,OPTPRMG,HIS,DESTAB,GEOM1, COORDO,EDOM,MTRAK,EPT,GEOM2,,MPT,EPTTABF,DV[TABF, XVALP,GEOM1P,,,,,PCOMPT,UBULK,TOPELE,PBRMSD,,,/ ,,DBCOPT,/ DESCYCL1///CNVFLG/3/OPTEXIT/DESMAX/MDTRKFLG/ DESPCH/DESPCH1/MODETRAK/EIGNFREQ/DSAPRT/PROTYPE/ BADMESH/XYUNIT $

DOM9 Performs the approximate optimization problem

DOM9 XINIT,DESTAB,CONSBL*,DPLDXI*,XZ,DXDXI,DPLDXT*,DEQATN,DEQIND,DXDXIT,PLIST2*,OPTPRMG,R1VALRG,RSP2RG,R1TABRG,CNTABRG,DSCMG,DVPTAB*,PROPI*,CONS1T,OBJTBG,COORDO,CON,SHPVEC,DCLDXT,TABDEQ,EPTTAB*,DBMLIB,BCON0,BCONXI,BCONXT,DNODEL,RR2IDR,RESP3RG,RQATABRG,TOPTAB,PBRMSD,TOPMC,TOPMC2,TMINIT,TOPELE,TPRELE,TOPSM/XO,CVALO,R1VALO,R2VALO,PROPO,R3VALO,TMINIT1/OBJIN/S,N,OBJOUT/PROTYP/EIGNFREQ/PROPTN/S,N,MXLAGM/ TREGION/UNUSED8/UNUSED9/UNUSED10/UNUSED11/UNUSED12/UNUSED13/UNUSED14 $

TOPSM Table of topological symmetric constraints.


202

Parameters:

Preprocesses design variables and designed property values.

Format:

Output Data Blocks:

MXLAGM Output-real-default=0.0. Maximum Lagrange multiplier for trust region analysis.

TREGION Input-integer-default=0. Trust region analysis flag. extracted from word position 60 in OPTPRMG.

=0

<>0

DOPR1 Preprocesses design variables and designed property values

DOPR1 EDOM,EPT,DEQATN,DEQIND,GEOM2,MPT,EDT,CASECC,TOPTAB0,TOPELE,PBRMS,BGPDT,ECT,GPECT,VELEM,CSTM/DESTAB,XZ,DXDXI,DTB,DVPTAB*,EPTTAB*,CONSBL*,DPLDXI*,PLIST2*,XINIT,PRO*PI*,DSCREN,DTOS2J*,OPTPRM,CONS1T,DBMLIB,BCON0,BCONXI,DMATCK,DISTAB,TOPTAB,PBRMSD,NWEDOM,NWCASE,TOPMC,TOPMC2,TMINIT,TOPELE,TPRELE,TOPSM/S,N,MODEPT/S,N,MODGEOM2/S,N,MODMPT/DPEPS/S,N,PROTYP/S,N,DISVAR/S,N,NRANVAR $

TOPSM Table of topological symmetric constraints.


Processes tables related to design sensitivity response evaluation, constraint screening and load case deletion.

Format:

Input Data Blocks:

DSAD Processes tables related to design sensitivity response evaluation

DSAD RSP1CT,R1TAB,RESP12,OBJTAB,CONTAB,BLAMA,CLAMA,LAMA,DIVTAB,AUXTAB,STBTAB,FLUTAB,OUG1DS,OES1DS,OSTR1DS,OEF1DS,OEFITDS,OES1CDS,OSTR1CDS,OQG1DS,DSCREN,XINIT,TABDEQ,COORDN,OL,FRL,FRQRSP,CASEDS,CASERS,UGX,OPTPRM,DVPTAB*,PROPI*,GPDT,DNODEL,WGTM,ONRGYDS,GLBTABDS,GLBRSPDS,RESP3,RMSTAB,RMSVAL,UPF,QPF,QMPF,UHF,OUGD1M,OESD1M,OSTRD1M,OEFD1M,MODRSP,CASEDM,PHG,OGPFB1DS,OELOP1DS,ONRGD1M,UPSDT,RQATAB,RESP12X,RESP3X,EPSSE,ESRT,OES1AB/R1VAL,R2VAL,RSP2R,R2VALR,CVAL,CVALR,OBJTBR,CNTABR,R1TABR,R1VALR,DRSTBL,FRQRPR,UGX1,AUG1,R1MAPR,R2MAPR,CASDSN,CASDSX,DRDUG,DRDUTB,CASADJ,LCDVEC,RR2IDR,R3VAL,R3VALR,RESP3R,RMSTABR,RMSVALR,FRLR,FOLR,UPFM,QPFM,QMPFM,UHFM,MODRPR,UPSDTR,RQATABR,RESP12XR,RESP3XR/WGTS/VOLS/S,N,OBJVAL/S,N,NR1OFFST/S,N,NR2OFFST/S,N,NCNOFFST/APP/DMRESD/SEID/DESITER/EIGNFREQ/S,N,ADJFLG/PEXIST/MBCFLG/RGSENS/PROTYP/AUTOADJ/FSDCYC/S,N,NR3OFFST/INREL/S,N,TADJCOL/SEID/S,N,ACTFREQ/S,N,FREQ1/S,N,DLOAD1/FREQ345/DISCYC/FRM $

OES1AB Table of screen element stresses for arbitrary beam cross sections.


204

Generates the design sensitivity coefficient matrix; i.e., the sensitivity coefficients for the retained set of constraints specified in the design model for each design variable.

Format:

Input Data Blocks:

Generates the aerodynamic spline transformation matrix.

Format:

Input Data Blocks:

DSAL Generates design sensitivity coefficient matrix

DSAL DRSTBL,DELWS,DELVS,DELB1,DELF1, COGRID,COELEM,OUGDSN,OESDSN,OSTRDSN, OEFDSN,OEFITDSN,OESCDSN,OSTRCDSN, OQGDSN,ONRGYDSN,OGPFDSN,OELOPDSN,R1VALR, TABDEQ,OL,DSDIV,DELX,DELS,DELFL,DELCE, DELGS,DELGM,FRQRPR,DELBSH,DRDUTB,ADELUS, ADELUF,R1TABR,DRMSVL,MODRPR,OUGDSNM, OESDSNM,OSTRDSNM,OEFDSNM,ONRGDSNM,ESRTDS,FRMDS,OES1ABDS/DSCM/NDVTOT/DELTAB/EIGNFREQ/ADJFLG/SEID/ S,N,ADELRS/S,N,ADELRF $

OES1ABDS Table of screened element stresses for arbitrary beam cross sections for the perturbed configuration.

GI Generates aerodynamic spline transformation matrix

GI AERO, ,BGPDT,AEBGPDT,AEUSET,AECOMP,CSTMA,

AEGRID/GPGK,GDGK $

AEGRID Basic grid point definition tables for the aerodynamic model. Output by APD as PGPDT with qualifier MODLTYPE='AEROMESH'.

SPLINE

AMSPLINE


Format:

Parameters:

Reads in the Bulk Data and outputs the finite element model in table form.

Format:

Parameters:

GYROLD Compute the gyroscopic static loads.

GYROLD CASECC,CSTM,BGPDT,SLT,KGGG*/PJR,UNUSED/GYLDOPT/LOADID/RFORSCAL/RACCSCAL $

GYLDOPT Input-integer-default=0. Static gyroscopic load generation option:

1 Compute the load for statics rotordynamics

2 Compute the coriolis matrix for dynamic analysis with static subcase (rotordynamics in rotating coordinates).

LOADID Input-integer-default=0. Load set identification number for the current subcase.

RFORSCAL Input-real-default=0. Scale factor for the loads defined in the RFORCE record.

RACCSCAL Input-real-default=0. Scale factor for the RACC value in the RFORCE record.

IFP Reads Bulk Data Section

IFP BULK/GEOM1,EPT,MPT,EDT,DIT,DYNAMIC,GEOM2, GEOM3,GEOM4,EPTA,PCOMPT,MATPOOL,AXIC,PVT,DMI, DMINDX,DTI,DTINDX,DEFUSET,EDOM,DEQATN,DEQIND, CONTACT,OINT,UNUSED25/ S,N,NOGOIFP/S,N,RUNIFP3/S,N,RUNIFP4/S,N,RUNIFP5/S,N,RUNIFP6/S,N,RUNIFP7/S,N,RUNIFP8/ S,N,RUNIFP9/SEID/S,N,RUNMEPT/S,N,RUNIFP10/S,N,RUNIFBS2 $

RUNIFBS2 Logical-output-default-FALSE. Set to TRUE if IFPBSH2 module execution is required.


206

Create PBAR and PBEAM Bulk Data entry records based upon data on PBARL and PBEAML Bulk Data entry records.

Format:

Input Data Block:

Parameter:

Example:

See the example in the module description of IFP, 205.

Filters the grid point force output table according to the MONPNT3 entries down to a single monitor point.

Format:

Input Data Blocks:

IFP9 Creates PBAR and PBEAM Bulk Data entry records

IFP9 EPT,GEOM1,EDT,GEOM2/EPTX,PBRMS/S,N,NOGOIFP9/ARBMPS/ARBMFEM $

GEOM2 Table of Bulk Data entry images related to element connectivity and scalar points.

ARBMPS Input-logical-default-FALSE.

ARBMFEM Input-logical-default-FALSE.

ILMPGPF

ILMPGPF MP3GPF,EDT,BGPDT,CSTM,OGPFB1/GPFMAT/NDDLNAME $

MP3GPF Table of monitor point type-3 responses.

Note: GPFLBL has been removed from the second output position.


Recovers up to five tables or matrices from a FORTRAN unit. This unit may have been written either by a FORTRAN program or by the companion module OUTPUT2.

Format:

Parameters:

Modifies, creates, or converts to matrices the LAMA (real eigenvalues) and CLAMA (complex eigenvalues) tables.

Formats:

Generate new LAMA table based on diagonals of a stiffness and mass matrix:

Input Data Blocks:

Output Data Blocks:

Remarks:4. Under NLAM=-3:

a. The frequency is computed:

INPUTT2 Input tables of matrices from a FORTRAN unit

INPUTT2 /DB1,DB2,DB3,DB4,DB5/ITAPE/IUNIT/LABL/S,N,HNAME1/S,N,HNAME2/S,N,HNAME3/S,N,HNAME4/S,N,HNAME5/S,N,DBKNT/NDDLNAM1/NDDLNAM2/NDDLNAM3/NDDLNAM4/NDDLNAM5 $

NDDLNAMi Input-character-default=blank. NDDL names corresponding to DB1 through DB5. If DBi is a matrix, then the corresponding NDDLNAMi is 'MATRIX'. Used only to read unformatted (binary) Fortran files created on non-native computers.

LAMX Eigenvalue Table Editor

LAMX KXX,MXX/LAMAX,LAMMAT/-3/RESFLG $

KXX Stiffness matrix in any set. Usually generalized.

MXX Mass matrix in any set. Usually generalized.

LAMMAT Diagonal matrix with real eigenvalues on the diagonal.


208

b. KXX and MXX may be vectors.

c. If a diagonal in MXX is null then the corresponding entry in LAMA table will be null.

d. If MXX is purged then an identity matrix is assumed.

e. If KXX is purged the module returns with no output.

f. LAMAX or LAMMAT may be purged.

Builds a table of monitor points.

Format:

Output Data Blocks:

Prints general matrix data blocks.

Format:

MAKMON Builds table of monitor points

MAKMON EDT, , /

,MONDISP,MONGRP,MP3LAB,MP3GPF/MKERRCHK $

MP3LAB Table of monitor point type-3 labels.

MP3GPF Table of monitor point type-3 responses.

MATPRN General matrix printer

MATPRN M1,M2,M3,M4,M5//PRTFORM $

Freq 0.5 Pi diag (KXX)

diag (MXX)----------------------------------=

AEROCOMP

STRUCOMP

AEROCOMP

AEMONPT

MONITOR


Parameters:

Prints messages to the standard MSC.Nastran output file.

Format:

Input Data Block:

Output Data Block:

Remarks:5. T1 and T2 may be purged.

6. T2 must be declared APPEND on the FILE statement if more than one MESSAGE execution is used to write into this table.

Example:2. Create a table of two messages and then print:

FILE TEST=APPEND $ maxint = 776705406 $ offset = 150704034 $ message /test/' maxint ='/maxint /' offset ='/offset $ lstart = maxint - offset $ incr = offset / 39 $ message /test/' starting column ='/lstart /' incr ='/incr $ message test/ $

The following will appear in the f06 file:

^^^ MAXINT = 776705406 OFFSET = 150704034 ^^^ STARTING COLUMN = 626001372 INCR = 3864206

PRTFORM Character-input-default=' '. Real number precision.

LONG 12 significant digits.

SHORT 4 significant digits.

MESSAGE Prints messages

MESSAGE T1/T2/P1/P2/.../Pn $

T1 Table created by prior executions of MESSAGE and will be printed to the f06 file.

T2 Table to which Pi will be written instead of the f06 file.


210

Generates splines to interpolated results from the structural model to the aero model.

Format:

Input Data Blocks:

Computes nonlinear analysis solution matrices and tables. Applicable to static structural or steady state heat transfer analysis.

Format:

Output Data Blocks:

MKSPLINE Generates splines to interpolated results from structural to aero model

MKSPLINE EDT,CSTMA,AEGRID,AECOMP,ECT,AEBOX/SPLINE $

ECT Element connectivity table.

AEBOX Table of aerodynamic element connectivity. Output by APD as BGPDT with qualifier MODLTYPE='AEROMESH'.

NLITER Computes nonlinear analysis solution matrices and tables

NLITER CASECC ,CNVTST ,PLMAT ,YSMAT ,KAAL ,ELDATA ,KELMNL ,LLLT ,GM ,MPT ,DIT ,MGG ,SLT1 ,CSTM ,BGPDT ,SIL ,USET ,RDEST ,RECM ,KGGNL ,ULLT ,GPSNT ,EDT ,DITID ,DEQIND ,DEQATN ,FENL ,EPT ,PCOMPT ,SLTNL /UGNI ,FGNL ,ESTNLH ,CIDATA ,QNV ,FFGH ,MUGNI ,MESTNL ,DUGNI ,BTOPCNV ,BTOPSTF ,FENL1 ,MDUGNI ,MDPSINI/S,N,LOADFAC/S,N,CONV/S,N,RSTEP/S,N,NEWP/S,N,NEWK/S,N,POUTF/S,N,NSKIP/LGDISP/S,N,NLFLAG/S,N,ITERID/S,N,KMATUP/S,N,LSTEP/S,N,KTIME/S,N,SOLCUR/TABS/S,N,KFLAG/S,N,NBIS/NORADMAT/S,N,LASTCNMU/SIGMA/S,N,ARCLG/S,N,ARCSIGN/S,N,TWODIV/LANGLE/S,N,ITOPT/S,N,ITSEPS/ITSMAX/S,N,PLSIZE/IPAD /IEXT /S,N,ADPCON/PBCONT/S,N,NBCONT/GPFORCE/GNLSTN /UNUSED/K6ROT $

MDPSINI Table of incremental rotation parameters with respect to the last converged step to be used for LANGLE=3.


Solves nonlinear static and transient response with an adaptive time increment for a given iteration.

Format:

Parameters:

NLSOLV Solves nonlinear static and transient response

NLSOLV CASEXX ,PPN ,YS ,ELDATA ,KELMNL ,KPP ,GMNE ,MPT ,DIT ,KFEFE ,DLT1 ,CSTM ,BGPDT ,SIL ,USETD ,BFEFE ,MFEFE ,NLFT ,RDEST ,RECM ,BPP ,GPSNT ,DITID ,DEQIND ,DEQATN ,MPP ,MBSP ,MBFEP ,MMP ,GMFE ,GMS ,RSPTQS ,RMPTQM ,GEOM4 ,KTPP ,YVELO ,YACCE ,GPTT1 ,EPT ,TMLDS ,ROTORT ,BGPP* ,KVCPP* /UPN ,IFS ,ESTNLH ,IFP ,OESNL ,PPL ,TEL ,MUPVNL ,MESTNL ,BTOPCNV ,BTOPSTF ,OESNLB1 ,FMV ,QPV ,DUPV ,RPV ,GEOM4CN ,KFRIC ,UNUSED1 ,UNUSED2 ,UNUSED3 ,UNUSED4 ,LTF ,UTF ,PNLT ,IFST ,PPLT ,UPNT ,FMVT ,ESTNL0 ,MESTNL0 ,UPNL0 ,FENL1 /KRATIO /S,N,CONV/S,N,STIME/S,N,NEWS/S,N,NEWK/S,N,OLDDT/S,N,NSTEP/LGDISP/S,N,CONSEC/S,N,ITERID/ITIME0 /S,N,KTIME/S,N,LASTUP/S,N,NOGONL/S,N,NBIS/MAXLP /TSTATIC /LANGLE /NDAMP /TABS /SIGMA /NORADMAT /S,N,ADPCON/PBCONT/S,N,NBCONT/CONT3D /S,N,MNEWK/S,N,NLOFLAG/NLATYPE/FKSYMFAC/RSTFLG /NLPACK /GPFORCE /GNLSTN /MSCHG /K6ROT /WTMASS /TSTATIC $

TSTATIC Input-integer-default=-1. Static analysis flag. Set to 1 to ignore inertia and damping forces.


212

Compares two data blocks and invokes dependencies.

Format:

Parameters:

Process rotordynamics Bulk Data input.

Format:

Input Data Blocks:

Parameters:

RESTART Data block comparison

RESTART DB1,DB2,DLSTIN/DLSTOUT/INVOKE/SPEXP/DPEXP/NDDLNAM/PRTUNIT $

PRTUNIT Input-integer-default=0. Fortran unit flag to print differences betwee DB1 and DB2.

=0 Print to f04.

<>0 Print to f06.

ROTOR Process rotordynamics Bulk Data input

ROTOR BGPDT,DYNAMIC,DIT,CSTM,VDA,EDOM/ROTOR,ROTORT/CONFAC/APP/ROTPRNT/ROTTFLG $

EDOM Table of Bulk Data entries that contain the DDVAL entries referenced by RSPINR records in DYNAMIC.

ROTPRNT Input-integer-default=1. Rotor summary print flag.

<>0 Print.

=0 Do not print.

ROTTFLG Input-integer-default=0. Rotordynamics transient solution sequence flag for extra point processing.

1: New method

0: Old method


Creates coriolis and circulation matrices based on rotordynamics user input and also drives DMAP rotor loop.

Format:

Input Data Blocks:

Parameters:

ROTRDR1 Creates coriolis and circulation matrices

ROTRDR1 BGPDT,CSTM,ROTOR,MG6,ROTORT/BCGG,TI,VGROT/S,N,RECNUM/S,N,ROTORID/CONFAC/WTMASS/S,N,METHSID/S,N,SDAMPSID/S,N,KDAMP/APP/ROTPRNT $

ROTORT Table of rotordynamics user input for transient analysis.

METHSID Output-integer-default=0. Eigenvalue extraction entry set identification number.

SDAMPSID Output-integer-default=0. Modal damping (TABDMP1) entry set identification number.

KDAMP Output-integer-default=0. Viscous modal to structural damping flag. If set to -1, then viscous modal damping (SDAMPING Case Control command) will be included in the stiffness matrix as structural damping:

1 Yes

2 No

APP Input-character-default='XXXXXXXX'. Analysis type.

'CEIGEN' Complex eigenvalues.

'FREQRESP' Frequency response.

''TRANRESP' Transient response.

'STATICS' Statics.

<>0 Print.

=0 Do not print.


214

Set parameters for rotordynamic looping.

Format:

Parameters:

Constructs the superelement map table and "corrects" the grid point locations at RSSCON element connections. The format has not changed but the SEP1XOVR parameter is now an output parameter which must be passed into SEP2X. Also additional options are available in SEP1XOVR.

Format:

Parameters:

ROTRDR2 Set parameters for rotordynamic looping

ROTRDR2 //

S,N,RECNUM/APP/ /S,N,ROTORID/S,N,SYNFLAG/

/ /S,N,GR/S,N,RAVG/

S,N,ALPHAR1/S,N,ALPHAR2 $

ALPHAR1 Output-real-default=0.0. Rayleigh damping coefficient for the rotor.

ALPHAR2 Output-real-default=0.0. Rayleigh damping coefficient for the rotor.

SEP1X Constructs superelement map table

SEP1X SELIST,GEOM1*,GEOM2*,GEOM4*,SETREE,SGPDTS*,BNDFIL/SEMAP,SGPDT,SCSTM/S,N,NOSE/CONFAC/QUALNAM/QUALVAL/S,N,RSFLAG/NQSET/EXTNAME/S,N,SEP1XOVR/NQMAX/SEBULK/TOLRSC/S,N,SWCHECK/ATQSET/S,N,RUNSEP2X $

RUNSEP2X Output-logical-default=FALSE. Flag to run SEP2X. Set to TRUE for models that contain certain types of weld elements.

CASECC

DIT ROTOR

ROTORT

FREQ

TIME

S,N,RSCALE0

S,N,OMEGA S,N,RSCALE1

S,N,OMEGADOT


Solves the matrix equation ] for using a preconditioned conjugate gradient method.

Format for Non-p-version Analysis:

Format for p-version Analysis:

Input Data Blocks:

SOLVIT Iterative solver

SOLVIT A,B,XS,PC,USET,KGG,GM,SIL,EQEXIN,EDT,CASECC,EQMAP,BGPDT,CSTM,PG,YS,KDICT,KELM,EST,MPT,DIT/X,R,PC1,EPSSE/SIGN/ITSOPT/ITSEPS/ITSMAX/IPAD/IEXT/ADPTINDX/NSKIP/MSGLVL/PREFONLY/S,N,ITSERR/SEID EBSOPT/CVMEM/CASPIV $

SOLVIT A,B,XS,PS,USET,USET0,SIL0,SIL,EQEXIN,EDT,CASECC,EQMAP,,,,,,,,,/X,R,PG,EPSSE/SIGN/ITSOPT/ITSEPS/ITSMAX/IPAD/IEXT/ADPTINDX/NSKIP/MSGLVL/PREFONLY/S,N,ITSERR/SEID $

BGPDT Basic grid point definition table. Only used for element based solver methods.

CSTM Table of coordinate system transportation matrices. Only used for element based solver methods.

PG Static load matrix applied to the g-set. Only used for the element based solver methods.

YS Matrix of enforced displacements. Only used for element based solver methods.

KDICT KELM dictionary table. Only used for element based solver methods.

KELM Table of element matrices for stiffness. Only used for element based solver methods.

EST Element summary table. Only used for element based solver methods.

MPT Material property table. Only used for element based solver methods.

DIT Table of TABLEij Bulk Data entry images. Only used for element based solver methods.

A[ ] X[ ] B[ ]±= X[ ]


216

Parameters:

EBSOPT Input-integer-default=0. Element-based solver option.

=-2 Determine whether element-based solver is selected for use.

=-1 Determine whether any element-based solver restrictions have been violated.

>0 A combination of bit values used to select solver options as follows:

Bit Value Option

0 0 Run solver with all defaults.

1 1 Use CASI solver.

2 2 Use VKI solver.

3 4 Reserved.

4 8 Reserved.

5 16 Reserved.

6 32 Reserved.

7 64 Use open core for solver memory.

8 128 Generate intermediate diagnostics.

9 256 Use alternate pcg method.

10 512 Reduce I/O (CASI solver only).

11 1024 Adapt PCG (CASI solver only).

12 2048 Do not use implicit elements (CASI solver only)

CVMEM Input-integer-default=16000. CASI virtual memory. Available if heap is used.

CASPIV Input-real-default-1.0E-10. Pivot threshold for CASI PCG factorization.


Prints table or matrix data blocks.

Format:

Parameters:

TABPT Table printer

TABPT TAB1,TAB2,TAB3,TAB4,TAB5//PRTFORM/UNUSED $

PRTFORM Character-input-default-' '. Real number print precision.

LONG 12 significant digits.

SHORT 4 significant digits.

UNUSED Input-logical-default=TRUE.


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