Lesson 3 3. Ply-Based Process Activities - …oss.jishulink.com/.../1460774184590_Lesson_3_Ply-Based_Process.pdf · 3. Ply-Based Process 4. ... Solution and Post-Processing 7. Laminate

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© 2013. Siemens Product Lifecycle Management Software Inc. All rights reserved

Siemens PLM Software

1. Introduction to Laminate Composite Simulation

2. Zone-Based Process

3. Ply-Based Process

4. Modeling 3D Laminates

5. Materials and Micromechanics

6. Solution and Post-Processing

7. Laminate Theory

8. Laminate Failure Analysis

9. Laminate Dynamic Simulation

10. Laminate Optimization

Activities:

• Ply-based process on the

motorcycle mud guard

• Draping plies on a part with

undevelopable surfaces

• Exchanging ply data with

Fibersim

Lesson 3

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Overview of the ply-based process

Step 1: Create your mesh using shell elements.

Step 2: Set the material orientation.

Step 3: On the mesh collector, create a laminate physical property and set the stacking recipe to Inherited from layup.

Step 4: Create a global layup by:

• Creating plies and stacking them in order to achieve desired properties.

• Selecting or creating the materials best suited to your application

• Attaching the plies to the mesh or the geometry using Draping options

Step 5: Create zones.

Step 6: Validate your layup.

Step 7: (Optional) Inflate your layup.

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Create mesh for global layup Create 2D shell meshes using:

• 2D Mesh

• 2D Mapped Mesh

• 2D Dependent Mesh

• Commands on the Element Operations toolbar

• The resulting meshes are not associated to geometry

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Element Copy Operations For the non-associative Element Copy operations:

• Translate

• Reflect

• Project

Any associated layups are automatically copied

3D Inflated Elements

• You should re-generate inflated elements using the copied parent 2D elements and their copied layups

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Element types supported by global layups

Solver 2D Elements

NX & MSC Nastran CQUAD4, QUADR, CQUAD8, CTRIA3, CTRIAR, CTRIA6

ANSYS SHELL91, SHELL99, SHELL181, SHELL281

ABAQUS S3, S3R, S4, S4R, S4R5,S8R, S8R5, STRI3,STRI65

LS-DYNA ELEMENT_SHELL

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Defining laminate properties

In the ply-based process, when you assign the laminate physical property to the Mesh

Collector, you need only define options in Solver Properties and Laminate

Properties groups.

You define the following properties in the Laminate Properties group.

• Stacking Recipe

• Must be set to Inherited from layup.

• Zone Angle Tolerance

• Element zones are computed by comparing the tolerance to the relative

change in ply angles between adjacent elements.

• The finer the tolerance, the more zones (and ultimately physical properties)

will be created.

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Layup Modeler The Layup Modeler dialog box is the main interface used to create or modify your global plies. You can access the Layup Modeler dialog box in the following ways:

• In the Laminates tab, click Global Layup .

•

•

Choose Insert→Laminate→Global Layup.

In the Simulation Navigator, right-click the Layups node and choose New

Layup. This option is available only if a global layup already exists.

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Creating a global layup In the Layup Modeler dialog box, you define:

• The stacking recipe.

• The stacking sequence, by creating plies and ply

groups.

From the Layup Modeler dialog box, you access the

Ply draping data dialog box to define the ply

boundaries and the draping properties.

Your layup and global plies are created as nodes in

the Simulation Navigator.

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Defining draping properties In the Draping Data dialog box, you specify or select:

• Draping solver.

• The lock angle for evaluating the quality of the draping.

• The draping path, either as a geodesic or a seed curve.

• Polygon faces or 2D elements to which you want to

drape the selected global ply or plies.

• The starting point for the draping.

• The primary and, optionally, secondary alignments at

the starting point.

• The draping mesh size, relative to the existing 2D mesh.

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Global layups and hand layup manufacturing

The global layup approach simulates the hand layup manufacturing workflow, in

which plies of resin-impregnated unidirectional or woven fabric (1) are sequentially

positioned on a mold (2).

Plies are positioned and oriented to meet specific design requirements.

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Draping solvers

Woven

• Computes fiber orientation for woven pre-pregs as a function of

surface curvature.

Unidirectional

• Computes fiber orientation for unidirectional tape computed as a

function of surface curvature.

Projection

• Simply projects the material orientation onto each element.

Fiber deviation is not computed.

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Woven solver The woven solver computes fiber orientation for cloth woven with two sets of fibers at an angle to each other:

•

•

Warp fiber direction set by the Primary Alignment.

Weft fiber direction set by the Secondary Alignment.

The solver accommodates distortion by changing the angle (3) between warp (1) and weft (2) fibers. The fibers do not stretch. Shear angle = Original yarn angle – Distorted yarn angle

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Unidirectional solver

The unidirectional solver models draping of unidirectional tape, oriented using the Primary Alignment.

Neighboring fibers may slide relative to one another while maintaining the same spacing relative to one another.

The shear angle (1) is a measure of fiber slippage.

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Woven and Unidirectional solvers

The ply Lock Angle is a material property that specifies the maximum tolerable amount of shear, or slippage in the case of unidirectional tape

The software compares the difference between the shear angle and Lock Angle.

Green — shear angle < 90% Lock Angle

Yellow — 90% Lock Angle < shear angle < Lock Angle Red — shear angle > Lock Angle

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Projection solver The projection draping solver allows you to replace the zone-based process by the ply-based process, without going into the details of fiber distortion. This could be interesting for:

•

•

Preliminary design

Detailed design of parts that have simple or flat geometry

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Draping Domain

• For the woven and unidirectional solvers, the selected polygon faces or 2D

elements must share at least one common edge.

• For the projection solver, you can select faces or 2D elements that are not contiguous.

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Material orientation

Woven and unidirectional solvers

• The material orientation affects the way the zone laminate properties are

created and displayed.

• It does not change the absolute fiber orientation computed by the solvers.

• Optionally, you can set the material orientation method to Inherited from

Layup, in the Mesh Associated Data dialog.

• This allows you to map the draped fiber orientation to the Material

Orientation by specifying one ply per surface from which the data will be

taken.

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Material orientation

Projection solver

• The ply orientations are defined relative to the material orientation.

• To avoid a circular reference, you must not set the material orientation to

Inherited from Layup.

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Global layups and hand layup manufacturing

Where the draping is difficult or impossible to perform, you can:

• Define a Cut Curve:

• This allows the draping algorithm to adjust the fiber orientations independently

on the two sides of the Cut Curve.

• The structural properties of the ply are not affected.

• Cut curves are defined on 2D element edges.

• You can also manually define a ply splice:

• You can split a polygon face using modeling operations or in the fem, and

manually partition the original ply into 2 or more distinct plies.

• This will result in a discontinuity in the fiber orientation around the splice.

• You can also change the start point location, or the start direction

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Layup offset You set the reference plane location using the Layup Offset node.

You can define a layup offset separately for each polygon face or element selection. Layup offset nodes

• • • •

Top Middle Bottom User defined — you need to specify the Bottom Fiber Distance value.

You modify the layup offset by right-clicking the appropriate node.

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Zones

A zone is a set of 2D or 3D elements that:

• Share the same global layup.

• Have the same fiber orientations for every ply within

the specified Zone Angle Tolerance.

Each zone has a unique laminate physical property

table that is then used by the structural solver.

• For each zone, you can:

• List zone properties.

• View the layup

• Create an element group to hide, display, or make

the elements easier to select.

• Create a laminate physical property table to modify,

examine, and manage it through the Physical

Property Table Manager dialog box.

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Overlap and orphan elements Zones also serves as an important validation and diagnostic tool. When the solver

computes zones, the following problematic elements are shown:

• Overlap Elements

• These are the elements that are referenced by more than one global layup.

• When the draping solver encounters these elements, it issues an error in the

Information window and stops computing zones.

• Orphan Elements

• These are the elements that have a laminate physical property with the

Inherited from layup option, and that do not have a defined ply.

• When the draping solver encounters these elements, it issues a warning in the

Information window and computes zones for other elements.

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Zones and Woven Fibers

The zoning algorithm uses the primary fiber

orientations to determine zone boundaries

• For woven fibers, this is the warp orientation

For woven ply materials, you can instruct the

code to also consider the secondary, or weft,

direction.

• This allows you to more accurately account for

the deviation of both fibers in the properties

used by the solver.

If you turn on this option:

• More zones will be created

• For each zone, a new ply material will be

computed on-the-fly, with the computed weft

fiber angle

• This new ply material will be exported to the

solver as a unique orthotropic material table

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Display Laminate Thickness and Offset

1. Create or update zones (This is required!)

2. In the Mesh Display dialog box, select Display 2D Element Thickness and Offset.

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Plot Laminate Thickness Contours

1. Create or update zones (This is required!)

2. Right-click the mesh node and select Plot Thickness Contours.

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Activity: Ply-based process on a motorcycle mud guard

This activity introduces the ply-based process, and shows the ease

with which it supports modifications like reinforcements. The

activity will guide you to:

• Create a global layup containing the 4 base plies.

• Add a global ply to the reinforced part

of the mud guard.

• Display thickness contours. Display

element thickness and offset.

• Use the Projection draping solver.

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Developable and undevelopable surfaces A developable surface is a one that can be flattened onto a plane without distortion. Developable surfaces have unique flat patterns

Developable surface Undevelopable surface

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Developable and undevelopable surfaces Fiber distortion and shearing is present only on undevelopable surfaces. To reduce or remove fiber distortion and shearing, use:

•

•

Cut curves

Splices

Fiber orientation is important in both, developable and undevelopable surfaces.

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Draping solver feedback

WARNING — Bad continuity detected for ply X. Draping results could be wrong. Check element normals, slope continuity and mesh density.

In the graphics window, the regions with bad continuity between elements are highlighted. Element edges and the element normal are shown in yellow.

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Draping solver feedback

WARNING — Flat Pattern of plyX tears or overlaps Y times. In the graphics window, the regions where elements tear or overlap are highlighted. Element edges are shown in red. WARNING — Flat Pattern of plyX might tear or overlap Y times. In the graphics window, the regions where elements might tear or overlap are highlighted. Element edges are shown in magenta.

• These warnings are issued when the algorithm detects stretching in fibers, which

could indicate that the ply cannot conform to the undevelopable faces.

• In practice, the ply would exhibit gapping or wrinkling on the mold.

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Activity: Draping plies on a part with undevelopable surfaces

This activity introduces the woven draping algorithm.

• Create a stacking sequence of 4 plies using a symmetric stacking recipe.

• Create cut curves and a splice to remedy

draping issues

• Review fiber orientations.

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Activity: Draping plies on a part with undevelopable surfaces

Notes • On slide 6, it can be difficult to select

the same node to define the start direction, as was used as the draping start point

• You may need to leave the cursor on top of the node, until the 3 dots appear to allow a QuickPick selection

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View flat pattern A flat pattern is the 2D shape that would result if you removed a ply from the mold and flattened it. For the plies draped with the Unidirectional and Woven solvers, you can:

•

•

Display the flat pattern(s).

Export the flat pattern(s) to part files.

Preview the flat pattern Part file containing the flat patterns

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Ply extensions

You can extend existing plies into layups other than their layup of origin.

• This allows you to simulate complex curing operations as well as the secondary

bonding process between pre-cured composite parts

Example

• In the following T-joint model, plies from the Vertical layup are extended into the

Horizontal layup.

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Imported layups

Use the Import Layup command to import

plies of a Fibersim ply-based laminate

(Fibersim CEE module) onto selected polygon

faces and/or 2D elements.

• After you import a layup, the imported

layup and its plies are accessible through

the Simulation Navigator.

• With the exception of the View Flat

Patterns command, you can access the

same commands for an imported layup as

for any other layup.

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Imported layups

How NXLC maps the Fibersim ply data to the 2D meshes in the fem:

• The Fibersim ply information is stored as a mesh of triangular elements

• When the layup is imported, NX maps the centroid of each selected 2D element

with a Fibersim triangular mesh element, using the specified tolerance, for each

ply.

• By default, NX calculates this tolerance value as the averaged NX meshed

element length.

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Ply import from Fibersim NX Laminate Composites reads from the Fibersim HDF5 file:

• Stacking sequence

• Fiber orientations

• Ply thickness

• Ply name

• Material name

• Material properties and units.

• Some properties, such as stress limits, may be missing

• You have a choice to override or not an existing NX material that has

the same name

• Starting point and direction of draping

• Ply angle (NX9.01)

• Rosette (NX9.01)

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Ply Export to Fibersim

NX Laminate Composites writes to the Fibersim HDF5 file:

• Stacking sequence

• Ply name

• By default, this is the NXLC global ply number

• If a ply description exists, it will replace the ply number

• Fiber orientations (NX 9.01)

• Only for re-import into NXLC, Fibersim does not use this data

• Material name

• Fibersim gets the ply thickness from its materials database via the material name

• Starting point and direction of draping

• 2D mesh for each ply.

• Fibersim computes ply boundaries from this mesh.

• Ply angle (NX9.01)

• Rosette (NX9.01)

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Assumptions and limitations when working with imported layups

• NX assumes that the draping of all plies starts from the same mold face.

• The imported layup must have been created with the same part geometry that is

meshed in NX.

• The coordinate system stored in the Fibersim file must be the same as the NX

absolute coordinate system.

• When you create a fibersim file using the Fibersim application in NX, the NX

absolute coordinate system is used by default.

• The units stored in the Fibersim file must be the same as the FEM units.

• NX reads the material property units and converts them to the FEM units.

• You cannot import an HDF5 file that you originally exported from NX, as the file

is intended for Fibersim and lacks some data necessary for NX.

• This limitation is removed in NX9.01

• You cannot import Fibersim cores.

• This limitation is partially removed in NX9.01

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Activity: Exchanging ply data with Fibersim

In this activity, you will:

•

•

•

Import laminate plies from Fibersim.

Modify the imported global layup.

Export the modified global layup to Fibersim.

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Review questions

1.

2.

3.

True/False. A developable surface is a surface that an be flattened onto a plane without distortion.

True/False. Draping in NX mimics closed molding processes such as compression molding or resin transfer molding.

True/False. For the projection solver, the selected polygon faces or 2D elements must have a least one common edge.

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Answers to review questions

1. True/False. A developable surface is a surface that an be flattened onto a plane without distortion.

• True. Developable surfaces have unique flat patterns that preserve the length of all paths on the surface.

2. True/False. Draping in NX mimics closed molding processes such as compression molding or resin transfer molding.

• False. Draping in NX mimics the hand layup manufacturing workflow, in which pieces of resin-impregnated unidirectional or woven fabric are individually positioned on a mold on top of each other.

3. True/False. For the projection solver, the selected polygon faces or 2D elements must have a least one common edge.

• False. For the projection solver, you can select faces or 2D elements that are not contiguous.

Documents

Lesson 3 3. Ply-Based Process Activities - …oss.jishulink.com/.../1460774184590_Lesson_3_Ply-Based_Process.pdf · 3. Ply-Based Process 4. ... Solution and Post-Processing 7. Laminate