SimXpert R3.2 Crash Workspace Guide

1Introduction

Crash Workspace GuideIntroduction

Overview and Definition2

Overview and DefinitionAn overview of the SimXpert crash workspace is given here.

IntroductionSimXpert crash is a preprocessor for graphically preparing input data for LS-DYNA, an explicit dynamic software, used in applications such as crash, crush, and drop test simulations. Use of crash workspace allows users to work within one common modeling environment with other SimXpert workspaces such as Structures. Thus, for example, a model originally prepared for NVH, linear, or implicit nonlinear analysis can be easily used in explicit applications (crash). This dramatically reduces the time spent to build different models for implicit and explicit analysis and prevents you from making mistakes because of unfamiliarity between different programs.

TheoryA detailed theory of explicit analysis is outside the scope of this guide. However, it is important to understand the basics of the solution technique, since it is critical to many aspects of using the SimXpert crash workspace. If you are already familiar with explicit methods and how they differ from implicit methods, you may disregard this section.

Method of SolutionAlthough crash simulation software, including LS-DYNA uses the Explicit methods, a brief overview of both the Implicit and the Explicit Methods for the solution of dynamic response calculations is given below.

Implicit Methods

Most finite element programs use implicit methods to carry out a transient solution. Normally, they use

Newmark schemes to integrate in time. If the current time step is step , a good estimate of the

acceleration at the end of step will satisfy the following equation of motion:

where:

= mass matrix of the structure

= damping matrix of the structure

= stiffness matrix of the structure

= vector of externally applied loads at step

n

n 1+

Ma'n 1+ Cv'n 1+ Kd'n 1++ + Fn 1+ext

=

MCKFn 1+

extn 1+

3IntroductionOverview and Definition

and the prime denotes an estimated value.

The estimates of displacement and velocity are given by:

or

where is the time step, and , and are constants.

The terms and are predictive and are based on values already calculated.

Substituting these values in the equation of motion results in

or

The equation of motion may then be defined as

The accelerations are obtained by inverting the matrix as follows:

This is analogous to decomposing the stiffness matrix in a linear static analysis. However, in dynamics, mass and damping terms are also present.

= estimate of acceleration at step

= estimate of velocity at step

= estimate of displacement at step

a'n 1+ n 1+v'n 1+ n 1+d'n 1+ n 1+

d'n 1+ dn vnΔt 1 2β–( )anΔt2( ) 2 βa'n 1++⁄ Δt

2+ +=

v'n 1+ vn 1 γ–( )anΔt γa'n 1+ Δt+ +=

d'n 1+ dn* βa'n 1+ Δt

2+=

v'n 1+ vn* γa'n 1+ Δt+=

Δt β γ

dn* vn

*

Ma'n 1+ C v*n γa'n 1+ Δt+( ) K d*n βa'n 1+ Δt2

+( )+ + Fn 1+ext

=

M CγΔt KβΔt2

+ +[ ]a'n 1+ Fn 1+ext

Cvn*– Kdn

*–=

M*a'n 1+ Fn 1+residual

=

M*

a'n 1+ M*1–Fn 1+

residual=


Explicit Methods

The equation of motion

can be rewritten as

where:

The acceleration can be found by inverting the mass matrix and multiplying it by the residual load vector.

In LS_DYNA, like any explicit finite element code, the mass matrix is lumped which results in a diagonal mass matrix.

Since is diagonal, its inversion is trivial, and the matrix equation is a set of independent equations for each degree of freedom, as follows:

The Leap-frog scheme is used to advance in time.

The position, forces, and accelerations are defined at time level , while the velocities are defined at time

level . Graphically, this can be depicted as:

= vector of externally applied loads

= vector of internal loads (e.g., forces generated by the elements and hourglass forces)

=

= mass matrix

Man Cvn Kdn+ + Fnext

=

Man Fnext

Fnint

–=

an M1–Fn

residual=

Fnext

Fnint

Cvn Kdn+M

M

ani Fniresidual

Mi⁄=

n

n 1 2⁄+

vn 1 2⁄+ vn 1 2⁄– an Δtn 1 2⁄+ Δtn 1 2⁄–+( ) 2⁄+=

dn 1+ dn vn 1 2⁄+ Δtn 1 2⁄++=


The Leap-frog scheme results in a central difference approximation for the acceleration, and is second-

order accurate in .

Explicit methods with a lumped mass matrix do not require matrix decompositions or matrix solutions. Instead, the loop is carried out for each time step as shown in the following diagram:

Explicit Time Step

Implicit methods can be made unconditionally stable regardless of the size of the time step. However, for explicit codes to remain stable, the time step must subdivide the shortest natural period in the mesh. This means that the time step must be less than the time taken for a stress wave to cross the smallest element in the mesh. Typically, explicit time steps are 100 to 1000 times smaller than those used with implicit codes. However, since each iteration does not involve the costly formulation and decomposition of matrices, explicit techniques are very competitive with implicit methods.

Because the smallest element in an explicit solution determines the time step, it is extremely important to avoid very small elements in the mesh.

n 1– n 1 2§– n n 1 2§+ n 1+ time

d F a, , d F a, , d F a, ,v v

Δt

Grid-Point Accelerations

Grid-Point Velocities Grid-Point Displacements

Element Stain Rates

Element Stresses

Element Forces at Grid-Points

+ External Forces at Grid Points

Leap-frog Integration in Time

Element Formulation and Gradient Operator

Constitutive Model and Integration

CONTACT, Fluid-Structure Interaction, Force/Pressure boundaries

Element Formulation and Divergence Operator


Courant Criterion

Since it is impossible to do a complete eigenvalue analysis every cycle to calculate the timestep, an approximate method, known as the Courant Criterion, is used. This is based on the minimum time which is required for a stress wave to cross each element:

where:

For 1-D elements, the speed of sound is defined as:

where:

Implicit vs. Explicit Analysis

The time step for implicit solutions can be much larger than is possible for explicit solutions. This makes implicit methods more attractive for transient events that occur over a long time period and are dominated by low frequency structural dynamics. Explicit solutions are better for short, transient events where the effects of stress waves are important. There is, of course, an area where either method is equally advantageous and may be used.

Explicit solutions have a greater advantage over implicit solutions if the time step of the implicit solution has to be small for some reason. This may be necessary for problems that include:

• Material nonlinearity. A high degree of material nonlinearity may require a small time step for accuracy.

• Large geometric nonlinearity. Contact and friction algorithms can introduce potential instabilities, and a small time step may be needed for accuracy and stability.

• Those analyses where the physics of the problem demands a small time step (e.g. stress wave effects as in crash, crush, and impact analyses).

= Timestep

= Timestep scale factor (<1)

= Smallest element dimension

= Speed of sound in the element material

= Young’s modulus

= density

tΔ SL/c=

ΔtSLc

c E ρ⁄=

Eρ


• Material and geometric nonlinearity in combination with large displacements. Convergence in implicit methods becomes more difficult to achieve as the amount of nonlinearity for all types increases.

Explicit Methods Have Increasing Advantages Over Implicit Methods as the Model Gets Bigger and Bigger.


9Parts and Geometry

Parts and Geometry

Parts and Geometry10

Parts and GeometryThe geometry of the parts can be either created in SimXpert, or more likely imported from CAD program such as Catia, Pro/E.

UnitsSimXpert interprets all dimensions and input data with respect to a system of units. It is important to set the appropriate units prior to importing any unitless analysis files (such as a Nastran Bulk Data file) or creating materials, properties, or loads. You can control the system of units by selecting Units Manager from the Tools menu. If you import a file that contains units, SimXpert will convert them into those specified in the Units Manager.

Creating GeometryIn the first release SimXpert has very limited geometry creation capabilities. It is possible to create curves and very simple surfaces. For the most part you will be importing geometry from an external source. The imported geometry can be edited in SimXpert

Importing GeometryIf the geometry of the part is available in a CATIA, parasolid, IGES, or STL file, it can be directly imported into the SimXpert Crash Workspace.

Creating local coordinate systemsSometimes it is convenient to use local coordinate systems for specifying loads, and or boundary conditions. For example, a certain node may have a roller support placed in an inclined plane. A local

11Parts and GeometryParts and Geometry

coordinate system with one of its axes normal to the inclined plane needs to be created and used to specify the fixity (SPC) of the displacement component along the direction normal to the inclined plane.

Local coordinate systems can be in cartesian, cylindrical or spherical systems. Coordinate system created in SimXpert are represented by the following icons, corresponding to the method selected.

You can create local coordinate systems by selecting Cartesian, Cylindrical, or Spherical from the Coordinate System group under the Geometry tab. There are numerous methods to create local coordinate systems in SimXpert:

Coordinate System

Direction 1

Direction 2

Direction 3 1-3 plane

Cartesian x y z x-z (y=0)

Cylindrical r z r-z ( =0)

Spherical r r- ( =0)

CONSTRAINTCONSTRAINT

Cartesian

Cylindrical

Spherical

θ θθ φ φ θ

Parts and Geometry12

1. 3 Points: Three points are used to define the coordinate system. The first point corresponds to the location of origin. The second point defines the point on a specified axis and the third point defines a point in a specified plane.

2. Euler: Creates a coordinate system through three specified rotations about the axes of an existing coordinate system.

3. Normal: Creates a coordinate system with its origin at a point location on a surface. A specified axis is normal to the surface.

4. Two Vectors: Creates a coordinate system with its origin at a designated location and two of the coordinate frame axes are defined using vectors

5. Advanced: Location and orientation can be independently defined. There are 4 different ways to define the location of the origin of the coordinate system: Geometry, Point/Node, Coordinate System, and Center of Part. Further, the orientation can also be defined 3 ways: Global, Two Axes, and Coordinate System.

13Materials

Materials

Materials14

MaterialsSimXpert Crash Workspace supports most of the LS-DYNA material types, covering isotropic, anisotropic, orthotropic, and laminated material properties. These material properties can be dependent on temperature, strain, and strain rate. Here we briefly describe all the material types supported currently by the crash workspace. Please refer to “LS-DYNA Keyword Users’ Manual”, for a full description of all the LS-DYNA supported materials.

Supported Materials

MAT_ADD_EROSION

This material model option provides a way of including failure in material models that do not allow failure and erosion. This option can also be applied to constitutive models with other failure and erosion criterion. Each of the criterion defined here is applied independently, and once any of them is satisfied, the element is deleted from further calculation.

Field Comments

Title Unique name identifying material model

Desc Optional description of the material model

TITLE_OPTION If selected material title option is used

MID Material identification number (Integer > 0) for which this erosion definition applies.

EXCL The Exclusion number. When any of the failure constants are set to the exclusion number, the associated failure criteria calculations are bypassed. For example, to prevent a material from going into tension, you may specify an unusual value for the exclusion number, e.g. 1234., set Pmin to 0.0 and all the remaining constants to 1234. The default value is 0.0, which eliminates all criteria from consideration that have their constants set to 0.0, or left blank.

PFAIL Pressure at failure, Pmin. Failure occurs when pressure is less than PFAIL

15MaterialsMaterials

Remarks:1. This failure model only applies to the 2D and 3D solid elements with one point integration.

See Also:• LS-DYNA Keyword User’s Manual

MAT_ANISOTROPIC_ELASTIC

This material model is used for modeling elastic anisotropic behavior of solids.

SIGP1 principal stress at failure, σmax. Failure occurs when the maximum principal stress exceeds SIGP1.

SIGVM Equivalent stress at failure, σvM. Failure occurs when the von Mises equivalent stress exceeds SIGVM.

EPSP1 Principal strain at failure, εmax. Failure occurs when the maximum principal strain exceeds EPSP1.

EPSSH Shear strain at failure, γmax. Failure occurs when the maximum shear strain exceeds EPSSH.

SIGTH Threshold stress, σ0 (used in evaluating the Tuler-Butcher criterion)

IMPULSE Stress impulse for failure, Kf. Failure occurs when the Tuler-Butcher criterion exceeds IMPULSE.

FAILTM Failure time. When the analysis time exceeds the failure time, the material is removed.

Field Contents

Title Unique name identifying the material model.

Desc Optional description of the material model.

Field Comments

../../../crash_quick_reference/ls-dyna_970_manual_k.pdf

Materials16


MAT_BLATZ-KO_RUBBER

This is used to model nearly incompressible continuum rubber. The Poisson’s ratio is fixed to 0.463


TITLE_OPTION If selected, the material Title will be exported to LS-DYNA

MID Material identification number. (Integer > 0)

RO Mass density.

C11... C66 Anisotropic constitutive matrix components

AOPT Material axes option

XP, YP, ZP Coordinates for point P (for AOPT= 1 and 4)

A1, A2, A3 Components of a vector a (for AOPT=2)

D1, D2, D3 Components of a vector d (for AOPT=2)

V1, V2, V3 Components of a vector v (for AOPT= 3 and 4)

BETA Material angle in degrees (for AOPT= 3)

REF Use Reference geometry to initialize the stress tensor

Field Comments




MID Material identification number (Integer > 0)

RO Mass Density of the material

G Shear modulus

REF Use reference geometry to initialize the stress tensor (0 =off; 1 = on)

Field Contents




MAT_CABLE_DISCRETE_BEAM

This material model is used to define elastic cables realistically.

Remarks:1. The force, F generated by the cable is nonzero if the cable is in tension. The force is given by:

F = max (F0 + KΔL, 0.)

where K is the stiffness, and ΔL is the change in length. If E is greater than zero, K is defined as:

K = (E X cross sectional area)/ (Initial length - offset)

2. A constant force element can be obtained by setting:

F0 > 0, and K = 0

Field Comments





RO Mass density

E Young’s modulus (if value greater than zero), or stiffness (if value smaller than zero)

LCID Load curve Id for loading (engineering stress vs. engineering strain)

F0 Initial Tensile Force

TMAXF0 Time for which pre-tension force will be held

TRAMP Ramp-up time for pre-tension force

IREAD Flag: If value greater than zero, use the value of OUTPUT from card 2.

OUTPUT Flag = 1 to output axial strain

Materials18

3. The cross section, and offset are defined on the *SECTION or *ELEMENT cards. For a slack cable, the offset should be input as a negative value. For an initial tensile force, the offset should be positive.

4. If a load curve is specified, the Young’s modulus will be ignored, and the load curve will be used instead. The points on the load curve are defined as engineering stress vs. engineering strain. The unloading behavior follows the loading.


MAT_ELASTIC

This LS-DYNA material model (001) is an isotropic elastic material available for beam, shell and solid elements.

Remarks:1. The axial and bending damping factors are used to damp down numerical noise. The update of the

force resultants, , and moment resultants, , includes the damping factors:

Field Contents





RO Mass density.

E Young’s modulus

PR Poisson’s ratio

DA Axial damping factor (used in Belytscho-Schwer beam type 2 only)

DB Bending damping factor (used in Belytscho-Schwer beam type 2 only)

Fi Mi




MAT_ELASTIC_FLUID

This LS-DYNA material model (001) is an isotropic elastic material available for solid elements.

Field Contents





RO Mass density.

E Young’s modulus


DA Axial damping factor (used in Belytscho-Schwer beam type 2 only)

DB Bending damping factor (used in Belytscho-Schwer beam type 2 only)

K Bulk Modulus (for fluid option)

VC Tensor viscosity coefficient (between 0.1 and 0.5)

CP Cavitation pressure (default = 1.0E+20)

Fin 1+

Fin

= 1DAΔt--------+

ΔFin 1 2⁄+

+

Min 1+

Min

= 1DBΔt--------+

ΔMin 1 2⁄+

+


Materials20

Remarks:1. The axial and bending damping factors are used to damp down numerical noise. The update of the

force resultants, , and moment resultants, , includes the damping factors:

2. Fluid like behavior is obtained with the following relationship between bulk modulus, K, and pressure rate, p:

A tensor viscosity VC, if used, which acts only on the deviatoric stresses


MAT_ELASTIC_PLASTIC_THERMAL

Temperature dependent material coefficients can be defined using this material type. A minimum of two temperature points are needed, and a maximum of eight can be defined.

Field Comments




Fi Mi

Fin 1+

Fin

= 1DAΔt--------+

ΔFin 1 2⁄+

+

Min 1+

Min

= 1DBΔt--------+

ΔMin 1 2⁄+

+

KE

3 1 2υ–( )------------------------=

p Kε··ii–=




MAT_ISOTROPIC_ELASTIC_PLASTIC

Defines an isotropic plasticity material with isotropic hardening. This is a very low cost plasticity model, suitable for 3D solids and plane stress elements. If used in shell elements, this material model leads to inaccurate shell thickness updates and stresses after yielding.



YM_LC Load curve defining Young’s modulus Vs. Temperatures.

PR_LC Load curve defining Poisson’s raito Vs. Temperatures.

A_LC Load curve defining the coefficent of thermal expansion Vs. Temperatures.

SIGY_LC Load curve defining Yield stressVs. Temperatures.

V_LC Load curve defining the plastic hardening modulus Vs. Temperatures.

Field Contents

Name Unique name identifying the material model.


Fields:


RO Mass density.

G Shear modulus.

SIGY Yield Stress.

ETAN Plastic hardening modulus

BULK Bulk modulus

Field Comments


Materials22

Remarks:1. In the plane stress implementation for shell elements, a one-step radial return approach is used to

scale the Cauchy stress tensor if the state of stress exceeds the yield surface.


MAT_LOW_DENSITY_FOAM

This material is used to model highly compressible low density foams. Its main applications are for seat cushions and padding on the Side Impact Dummies (SID). Optionally, a tension cut-off failure can be defined.

Field Contents



Fields:


RO Mass density.

E Young’s modulus

LCID Load Curve Id for nominal stress versus strain

TC Tension cut-off stress

HU Hysteric unloading factor (between 0 and 1). Default is 1 (no energy dissipation)

BETA Decay constant (β) for creep in unloading



Remarks:

The compressive behavior is illustrated in Figure 1 where hysteresis on unloading is shown. This behavior under uniaxial loading is assumed not to significantly couple in the transverse directions. In tension the material behaves in a linear fashion until tearing occurs. Although the implementation may be somewhat unusual, it was motivated by Storakers (1986).

The model uses tabulated input data for the loading curve where the nominal stresses are defined as a function of the elongations, , which are defined in terms of the principal stretches, , as:

DAMP Viscous damping coefficient (0.05< recommended value < 0.50) to model damping effects.

LT. 0: the absolute value of DAMP is used as the load curve which defines the damping coefficient as a function of the maximum strain in compression εmax (see Remark 1). In tension, the damping constant is set to the value corresponding to the strain at 0.

SHAPE Shape factor for unloading. Active for non-zero values of the Hysteric unloading factor (HU)

FAIL Failure option, after cut-off stress reached.

= 0, Tensile stress remains at cut-off value

= 1, Tensile stress is reset to zero

BVFLAG Bulk viscosity activation flag

= 0, No bulk viscosity (recommended, default)

= 1, Bulk viscosity active

ED Young’s relaxation modulus Ed (optional), for rate effects.

BETA1 Optional Decay constant β1

KCON Stiffness coefficient for contact interface stiffness. If undefined, the maximum slope in the stress vs. strain curve is used.

REF Use Reference geometry to initialize the stress tensor. The reference geometry is defined by the keyword: *INITIAL_FOAM_REFERENCE_GEOMETRY.

= 0, Off

= 1, On

Field Contents

εi λi

εi λi 1–=

Materials24

The stretch ratios are found by solving for the eigenvalues of the left stretch tensor, , which is obtained

via a polar decomposition of the deformation gradient matrix, . Recall that,

The update of follows the numerically stable approach of (Taylor and Flanagan 1989). After solving

for the principal stretches, we compute the elongations and, if the elongations are compressive, the corresponding values of the nominal stresses, are interpolated. If the elongations are tensile, the

nominal stresses are given by

and the Cauchy stresses in the principal system become

The stresses can now be transformed back into the global system for the nodal force calculations.

Additional Remarks:1. When hysteretic unloading is used the reloading will follow the unloading curve if the decay

constant, , is set to zero. If is nonzero the decay to the original loading curve is governed by the expression:

2. The bulk viscosity, which generates a rate dependent pressure, may cause an unexpected volumetric response and, consequently, it is optional with this model.

3. The hysteretic unloading factor results in the unloading curve to lie beneath the loading curve as shown below. This unloading provide energy dissipation which is reasonable in certain kinds of foam.

4. Note that since this material has no effective plastic strain, the internal energy per initial volume is written into the output databases.

5. Rate effects are accounted for through linear viscoelasticity by a convolution integral of the form

where is the relaxation function.

The stress tensor augments the stresses determined from the foam. Consequently, the final stress, is taken as the summation of the two contributions:

Vij

Fij

Fij RikUkj VikRkj= =

Vij

τi

τi Eεi=

σi

τi

λiλk----------=

β β

1. eβt–

–

σijr

gijkl0

t

t τ–( )∂εkl

∂τ---------dτ=

gijkl t τ–( )

σi j

σij σijf σij

r+=


Since we wish to include only simple rate effects, the relaxation function is represented by one term from the Prony series:

given by,

This model is effectively a Maxwell fluid which consists of a damper and spring in series. We characterize this in the input by a Young's modulus, , and decay constant, .The formulation is performed in the local system of principal stretches where only the principal values of stress are computed and triaxial coupling is avoided. Consequently, the one-dimensional nature of this foam material is unaffected by this addition of rate effects. The addition of rate effects necessitates twelve additional history variables per integration point. The cost and memory overhead of this model comes primarily from the need to “remember” the local system of principal stretches.

Figure 1 Behavior of the Low Density Urethane Foam Model

6. The time step size is based on the current density and the maximum of the instantaneous loading slope, E, and ECON. If ECON is undefined the maximum slope in the loading curve is used instead.


g t( ) α0 ameβt–

m 1=

N

+=

g t( ) Edeβ1t–

=

Ed β1


Materials26

MAT_MOONEY_RIVLIN_RUBBER

This LS-DYNA material is used to define material properties for a two-parameter material model for rubber.

Remarks:

The strain energy density function is defined as:

Field Contents



Fields:


PR Poisson’s ratio.

RO Mass density.

A Mooney Rivlin Constant, A

B Mooney Rivlin Constant, B


=0, Off

= 1, On

SGL Specimen Gauge length, l0SW Specimen width

ST Specimen thickness

LCID Load Curve Id defining the force versus actual length change (ΔL) in the gauge length.

W A I 3–( ) B II 3–( ) C III2–

1–( ) D III 1–( )2+ + +=


C = 0.5A + B

D = A(5ν - 2) + B(11ν -5)/(2(1 - 2ν))

ν = Poisson’s ratio

2(A + B) = Shear modulus of linear elasticity

I, II, III are the three invariants of the Cauchy-Green Tensor

The load curve definition that provides the uniaxial data should give the change in gauge length, ,

versus the corresponding force. In compression both the force and the change in gauge length must be specified as negative values. In tension the force and change in gauge length should be input as positive values. The principal stretch ratio in the uniaxial direction, , is then given by

with L0 being the initial length and L being the actual length.

Alternatively, the stress versus strain curve can also be input by setting the gauge length, thickness, and width to unity (1.0) and defining the engineering strain in place of the change in gauge length and the nominal (engineering) stress in place of the force (Figure 2).

ΔL

λ1

λ1

L0 ΔL+

L0-------------------=

Materials28

Figure 2 Uniaxial Specimen for Experimental Data

The least square fit to the experimental data is performed during the initialization phase and is a comparison between the fit and the actual input is provided in the printed file. It is a good idea to visually check to make sure that it is acceptable. The coefficients A and B are also printed in the Dyna output file.

The stress versus strain curve can used instead of the force versus the change in the gauge length by setting the gauge length, thickness, and width to unity (1.0) and defining the engineering strain in place of the change in gauge length and the nominal (engineering) stress in place of the force (Figure 3).

Figure 3 Experimental Data from Uniaxial Specimen




MAT_NONLOCAL

Defines failure criterion to be dependent on the state of the material within a radius of influence which surrounds the integration point. With this failure model, the mesh size sensitivity of failure is greatly reduced, giving better convergence to a unique solution as the mesh is refined.


Field Comments




MID Non local Material identification number (Integer > 0)

PID Part Id for non local material

P Exponent of weighting function. A typical value might be 8., depending on the choice of the value for L.

Q Exponent of weighting function. A typical value might be 2.

L Characteristic length. This length should span a few elements

NFREQ Number of time steps before updating neighbors. Since the nearest neighbor search can add significant computational time, NFREQ should be set to value of 10 to 100.

NL1,,, NL8 History variable Ids for non local treatment

XC1, YC1, ZC1 Coordinate of point on symmetry plane

XC2, YC2, ZC2 Coordinate of a point along the normal vector


Materials30

MAT_ORTHOTROPIC_ELASTIC

This LS_Dyna material model (002) is an orthotropic elastic material available for solids, shells, and thick shells.

Field Contents





RO Mass density.

EA Young’s modulus in a-direction

EB Young’s modulus in b-direction

EC Young’s modulus in c-direction

PRBA Poisson’s ratio (νba)

PRCA Poisson’s ratio (νca)

PRCB Poisson’s ratio (νcb)

GAB Shear modulus (Gab)

GBC Shear modulus (Gbc)

GCA Shear modulus (Gca)

AOPT Material axis option

G Shear modulus for frequency dependent damping

SIGF Limit stress for frequency independent frictional damping

XP, YP, ZP Coordinates for point P (for AOPT= 1 and 4)


Remarks:

The material law that relates stresses to strains is defined as:

where is a transformation matrix, and is the constitutive matrix defined in terms of the material

constants of the orthogonal material axes, , , and . The inverse of for the orthotropic case is

defined as:

Note that

A1, A2, A3 Components of a vector a (for AOPT=2)

D1, D2, D3 Components of a vector d (for AOPT=2)

V1, V2, V3 Components of a vector v (for AOPT= 3 and 4)

BETA Material angle in degrees (for AOPT= 3)


Field Contents

C˜

T˜

TC˜ LT

˜=

T˜

C˜ L

a b c C˜ L

C˜ L

1–

1Ea------

νba

Eb--------–

νca

Ec-------– 0 0 0

νab

Ea--------–

1Eb------

νcb

Ec-------– 0 0 0

νac

Ea-------–

νbc

Eb-------–

1Ec----- 0 0 0

0 0 01

Gab--------- 0 0

0 0 0 01

Gbc--------- 0

0 0 0 0 01

Gca---------

=

νab

Ea--------

νba

Eb--------

νca

Ec-------,

νac

Ea-------

νcb

Ec-------,

νbc

Eb-------= = =

Materials32

The frequency independent damping is obtained by having a spring and slider in series as shown in the following sketch:

This option applies only to orthotropic solid elements and affects only the deviatoric stresses.


MAT_PIECEWISE_LINEAR_PLASTICITY

Defines elasto-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. Also, failure based on a plastic strain or a minimum time step size can be defined.

Field Contents



Fields:


E Young’s modulus. (Real > 0.0 or blank)


RO Mass density.

SIGY Yield Stress.

ETAN Tangent modulus (ignored if LCSS.GT. 0 is defined)

G

σfric



Remarks:

The stress strain behavior may be treated by a bilinear stress strain curve by defining the tangent modulus, ETAN. The most general approach is to use the table definition (LCSS) discussed below.

Three options to account for strain rate effects are possible.

1. Strain rate may be accounted for using the Cowper and Symonds model which scales the yield stress with the factor

where, is the strain rate

If VP=-1, the deviatoric strain rates are used instead.

If the viscoplastic option is active, VP=1.0, and if SIGY is > 0 then the dynamic yield stress is computed from the sum of the static stress,

FAIL Failure Flag

LT. 0: User defined failure subroutine is called to determine failure

EQ. 0.0: Failure not considered

GT. 0.0: Plastic strain to failure. When the plastic strain reaches this value, the element is deleted from the calculation.

TDEL Minimum time step size for automatic element deletion

C Strain rate parameter, C

P Strain rate parameter, P

LCSS Load Curve Id or Table Id defining effective stress versus effective plastic strain. The tableId defined for each strain rate a value of load curve Id giving the stress versus effective plastic strain for that rate.

LCSR Load Curve Id defining strain rate scaling effect on yield stress

VP Formulation for rate effects

=-1, Cowper-Symnods with deviatoric strain rate rather than total

= 0, Scale yield stress

= 1, Viscoplastic formulation

Field Contents

1ε·

C----

1 p⁄+

ε·

ε· ε· ijε·

ij=

Materials34

which is typically given by a load curve ID, and the initial yield stress, SIGY, multiplied by the Cowper-Symonds rate term as follows:

where the plastic strain rate is used. If SIGY=0, the following equation is used instead where the static stress

must be defined by a load curve:

This latter equation is always used if the viscoplastic option is off.

2. For complete generality a load curve (LCSR) to scale the yield stress may be input instead. In this curve the scale factor versus strain rate is defined.

3. If different stress versus strain curves can be provided for various strain rates, the option using the reference to a table (LCSS) can be used. See figure below.

σys εeff

p( )

σy εeffp ε· eff

p,( ) σy

s εeffp( ) SIGY

ε· effp

C-------

1 p⁄

⋅+=

σys εeff

p( )

σy εeffp ε· eff

p,( ) σy

s εeffp( ) 1

ε· effp

C-------

1 p⁄

+=


Figure 4 Rate effects may be accounted for by defining a table of curves. If a table Id is specified a curve Id is given for each strain rate. Intermediate values are found by interpolating between curves. Effective plastic strain versus yield stress is expected. If the strain rate values fall out of range, extrapolation is not used; rather, either the first or last curve determines the yield stress depending on whether the rate is low or high, respectively.

4. A fully viscoplastic formulation is optional (variable VP) which incorporates the different options above within the yield surface. An additional cost is incurred over the simple scaling but the improvement in results can be dramatic.



Materials36

MAT_PLASTIC_KINEMATIC

Defines elasto-plastic material with isotropic and kinematic hardening with or without rate effects.

Field Contents



Fields:




RO Mass density.

SIGY Yield Stress.

ETAN Tangent modulus

BETA Hardening parameter

= 0: Kinematic hardening

= 1: Isotropic hardening

1 < BETA > 0: Combined hardening

SRC Strain rate parameter, C, for Cowper Symonds strain rate model. If zero, rate effects are ignored.

SRP Strain rate parameter, P, for Cowper Symonds strain rate model. If zero, rate effects are ignored.

FS Failure strain for eroding elements

VP Formulation for rate effects:

= 0, Scale yield stress (default)



Remarks:

Figure 5 Elastic-plastic behavior with kinematic and isotropic hardening where l0 and l are respectively undeformed and deformed lengths of uniaxial tension specimen, and Et is the slope of the bilinear stress vs. strain curve.

Strain rate may be accounted for using the Cowper and Symonds model which scales the yield stress with the factor

where, is the strain rate

1ε·

C----

1 p⁄+

ε·

Materials38

A fully viscoplastic formulation is optional which incorporates the Cowper and Symonds formulation within the yield surface. Although an additional computational cost is incurred, the improvement in the results can be substantial. To ignore strain rate effects, set both SRC and SRP to zero.


MAT_POWER_LAW_PLASTICITY

Defines an isotropic plasticity material model with rate effects which uses a power law for hardening.

Field Contents



Fields:


RO Mass density.



K Strength coefficient

N Hardening exponent

SRC Strain rate parameter, C. If zero, rate effects are ignored.

SRP Strain rate parameter, P. If zero, rate effects are ignored.

ε· ε· ijε·

ij=



Remarks:

The yield stress, σy is a function of plastic strain, and obeys the following equation:

where, yp is the strain rate to yield, and p is the effective plastic strain (logarithmic).

The parameter SIGY governs how the strain to yield is identified. If SIGY is set to zero, the strain to yield is found by solving for the intersection of the linear elastic loading with the strain hardening equation:

which gives the elastic strain at yield as:

If SIGY is set to nonzero, and greater than 0.02 then:

SIGY Yield Stress (optional). Generally this parameter is not necessary (See Remarks)

VP Formulation for rate effects:

= 0, Scale yield stress (default)


Field Contents

( )nn py ypk kσ ε ε ε= = +

ε· ε

n

E

k

σ εσ ε

==

1

1n

yp

E

kε

− =

1

ny

yp k

σε

=

Materials40

Strain rate is accounted for using the Cowper-Symonds model which scales the yield stress with the following factor:

where is the strain rate. A fully viscoplastic formulation is optional with this model which incorporates

the Cowper-Symonds formulation within the yield surface. Although an additional cost is incurred, the improvement in results can be substantial.


MAT_RIGID

This material model is used to model parts made from rigid materials. Also, the coupling of a rigid body with MADYMO, and CAL3D can be defined via this material. Alternatively, a VDA surface can be attached as surface to model the geometry, e.g., for the tooling in metal-forming applications. Also, global and local constraints on the mass center can be optionally defined. Optionally, a local consideration for output and user-defined airbag sensors can be chosen.

Field Contents





1

1P

Cε +

ε·



RO Mass density



N MADYMO3D coupling flag.

COUPLE Coupling Option

ALIAS VDA Surface alias Name

CMO Center of mass constraint option

=1, Constraints applied in global directions

=0, No constraints

=-1, Constraints applied in local directions

CON1 First constraint parameter

=0, No constraints

=1, Constrained x displacement

=2, Constrained y displacement

=3, Constrained z displacement

=4, Constrained x and y displacements

=5, Constrained y and z displacements

=6, Constrained z and x displacements

=7, Constrained x, y, and z displacements

Field Contents

Materials42

Remarks:1. A rigid material provides a convenient way of turning one or more parts comprised of beams,

shells, or solid elements into a rigid body. Approximating a deformable body as rigid is a preferred modeling technique in many real world applications. For example, an engine block in a car crash simulation can be treated as rigid. Elements belonging to a rigid material are bypassed in the element processing and no storage is allocated for storing history variables. Consequently, using a rigid material is very cost efficient.

2. The inertial properties are calculated from the geometry of the constituent elements and the density RO as specified on the MAT_RIGID.

3. The initial velocity of a rigid material is calculated from the initial velocity of the constituent grids.

4. A rigid body can be made up of disjoint meshes. All elements that are part of a rigid body will move together as one rigid, even if they are disjoint.

5. Motion control for a rigid material can be defined using the BOUNDARY_SPC entry. The SPC must be applied to one grid point only.

6. Load control for a rigid material can be defined using the FORCE and MOMENT entries. These loads can be applied to any grid point that belongs to the rigid body. The forces and moments acting on the grid points will be accumulated and applied to the rigid body.

7. If no constraints are specified for the rigid material (CMO=0) the nodes belonging to the rigid material are scanned to determine constraints of the rigid material in global directions. If constraints are specified for the rigid material (CMO equal to +1 or –1), the nodes belonging to the rigid material are not scanned

CON2 Second constraint parameter

=0, No constraints

=1, Constrained x rotation

=2, Constrained y rotation

=3, Constrained z rotation

=4, Constrained x and y rotations

=5, Constrained y and z rotations

=6, Constrained z and x rotations

=7, Constrained x, y, and z rotations

LCO Local coordinate system for output

A1-V3 The components of two vectors a and v fixed in the rigid body for output.

Field Contents


8. Constraint directions for rigid materials (CMO equal to +1 or –1) are fixed, that is, not updated, with time.


MAT_SEATBELT

This material model is used to define the stretch characteristics and mass properties for seat belts.

Remarks:1. The Load curves for loading and unloading should start at the origin (0, 0), and contain positive

force and strain values only. The belt material is tension only, with zero forces being calculated whenever the strain becomes negative (compressive). The first nonzero point on the loading curve defines the initial yield point of the material. On unloading, the unloading curve is shifted along the strain axis until it crosses the loading curve at the yield point from which unloading starts. If the initial yield has not yet exceeded, or the origin of the (shifted) unloading curve is at negative strain, the original loading curve will be used for both loading and unloading. If the strain is less than the strain at the origin of the unloading curve, the belt is slack, and no force is generated. Otherwise, forces will be determined by the unloading curve for unloading, and reloading until the strain again exceeds yield after which the loading curve will again be used.

Field Comments





MPUL Mass per unit length

LLCID Load curve Id for loading (Force vs. engineering strain)

ULCID Load curve Id for unloading (Force vs. engineering strain)

LMIN Minimum length for elements connected to slip rings and retractors


Materials44

2. A small amount of damping is automatically included, to reduce high frequency oscillation. The damping force, D opposes the relative motion of the nodes, and is limited by stability:

D = (0.1 X Mass X Relative velocity)/(Time step size)

The magnitude of the damping force is limited to one-tenth of the force calculated from the force vs. strain relationship, and is zero when the belt is slack. Damping forces are not applied to elements attached to slip rings and retractors.


MAT_SOIL_AND_FOAM

This simple material model works similar to fluid. It should be used only in situations when soils and foams are confined within a structure or when geometric boundaries are present.

Field Comments






G Shear modulus

BULK Bulk modulus for unloading

A0, A1, A2 Yield function constants

PC Pressure cut off for tensile fracture

VCR Volumetric crushing option:

0.0: on,

1.0: loading and unloading paths are the same



Remarks:1. Pressure is positive in compression

2. Volumetric strain is given by the natural log of the relative volume and is negative in compression

3. Relative volume is the ratio of current volume to the initial volume at the start of the calculation

4. If the pressure drops below the cutoff value specified, it is reset to that value


MAT_VISCOELASTIC

This material model is used to define viscoelastic behavior for beams (Hughes-Liu), shells, and solids

Remarks:1. The shear relaxation behavior is described by [Hermann and Peterson, 1968]:

REF use reference geometry to initialize the pressure

LCID Load curve Id defining pressure vs. volumetric strain

Field Comments






BULK Bulk modulus for unloading

G0 Short time shear modulus

GI long time (Infinite) Shear modulus

BETA Decay constant

Field Comments

G t( ) GI G0 GI–( )eβt–

+=


Materials46


MAT_HIGH_EXPLOSIVE_BURN

This material model is used to input the detonation properties of high explosive materials.


Field Comments






D Detonation Velocity

PCJ Chapman-Jouget pressure

BETA Beta burn flag

0: Beta and programmed burn

1: Beta burn only

2: Programmed burn only

K Bulk Modulus (Beta = 2)

G Shear Modulus (Beta = 2)

SIGY Yield Stress (Beta = 2)




MAT_NULL

The use of this material model allows equations of state without computing deviatoric stresses.


Field Comments






PC Pressure Cutoff

MU Dynamic Viscosity Coefficient

TEROD Relative Volume for Erosion in Tension

CEROD Relative Volume for Erosion in Compression

YM Young’s Modulus (used for null beams and shells only)

PR Poisson’s ratio (used for nul beams and shells only)


Materials48

MAT_ELASTIC_PLASTIC_HYDRO

This material model is used to model an elastic-plastic hydrodynamic material.


Field Comments






G Shear Modulus

SIGY Yield Stress

EH Plastic hardening modulus

PC Pressure Cutoff

FS Failure strain for Erosion




MAT_ELASTIC_PLASTIC_HYDRO_SPALL

This material model is used to model an elastic-plastic hydrodynamic material with spall to represent splitting, cracking, and failure under tensile loads.


Field Comments






G Shear Modulus

SIGY Yield Stress

EH Plastic hardening modulus

PC Pressure Cutoff

FS Failure strain for Erosion

A1 Linear Pressure Hardening Coefficient

A2 Quadratic Pressure Hardening Coefficient

SPALL Spall Type



Materials50

MAT_STEINBERG

This material model is used to model materials deforming at very high strain rate for use with solid elements. The yield strength is a function of temperature and pressure.

Field Comments






G0 Basic shear modulus

SIG0 Yield Stress, σ0

BETA Parameter β, used in the equation defining Yield Strength

N Parameter n, used in the equation defininig Yield Strength

GAMA Initial Plastic Strain γi

SIGM σm

B Parameter b, used in the equation defininig Yield Strength

BP Parameter , used in the equation defininig Yield Strength

H Parameter h, used in the equation defininig Yield Strength

F Parameter b, used in the equation defininig Yield Strength

A Atomic Weight

TM0 Melting Temperature

b'



GAM0 Yield Stress equation Parameter, Gama_0

SA Melting Temperature equation Parameter, a

PC Pressure Cutoff

SPALL Spall Type

0: Default set to 2.0

1: P >= PC

2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed

3: P< -PC, element spalls and tension, p < 0, is never allowed

RP Melting Temperature equation parameter,

FLAG Set 1 for μ coefficients for the cold compression energy fit

NMN Optional minimum value for μ or ηNMX Optional maximum value for μ or ηECi Cold Compression Energy coefficients

Field Comments

r'


Materials52

MAT_STEINBERG_LUND

This material model is used to input the properties of a Steinberg and Lund [1999].material model for including the strain rate effect.

Field Comments






G0 Basic shear modulus

SIG0 Yield Stress, σ0

BETA Parameter β, used in the equation defininig Yield Strength

N Parameter n, used in the equation defininig Yield Strength

GAMA Initial Plastic Strain γi

SIGM σm

B Parameter b, used in the equation defininig Yield Strength

BP Parameter , used in the equation defininig Yield Strength

H Parameter h, used in the equation defininig Yield Strength

F Parameter b, used in the equation defininig Yield Strength

b'



A Atomic Weight

TM0 Melting Temperature

GAM0 Yield Stress equation Parameter, Gama_0

SA Melting Temperature equation Parameter, a

PC Pressure Cutoff

SPALL Spall Type


1: P >= PC



RP Melting Temperature equation parameter,

FLAG Set 1 for μ coeeficients for the cold compression energy fit

NMN Optional minimum value for μ or ηNMX Optional maximum value for μ or ηECi Cold Compression Energy coefficients

UK Activation Energy for rate dependent model

C1 Exponent prefactor in rate dependent model

C2 Coefficient of drag term rate dependent model

YP Peierls stress for rate dependent model

YA Ahtermal yield stress for rate dependent model

YM Work hardening max for rate dependent model

Field Comments

r'


Materials54

MAT_ISOTROPIC_ELASTIC_FAILURE

This material model is used to define the properties of a non-iterative plasticity model with simple plastic strain failure criteria.

Field Comments






G Shear Modulus

SIGY Yield Stress

ETAN Plastic Hardening Modulus

BULK Bulk Modulus

EPF Plastic Failure Strain

PRF Failure Pressure

REM Element Erosion option

0: Eroded at failure

1: no removal of element, (except if TERM = 1, and element time step size falls below Δt)

TREM Δt for element removal

0: Δt is not considered

1: yes, if element time step size falls below Δt



MAT_SOIL_AND_FOAM_FAILURE

This material model is used to define the material properties for a soil and foam model. This material model works similar to fluid, and should be used only in situations when soils and foams are confined within a structure or when geometric boundaries are present.In this material model, the material loses its ability to carry tension when the pressure exceeds the failure pressure.

Field Comments






G Shear Modulus

BULK Bulk Modulus for unloading

A0, A1, A2 Plastic Yield Function Constants

PC Pressure Cutoff for Tensile Fracture

VCR Volumetric Crushing Option

0: On

1: Loading and unloading paths are the same


Materials56


MAT_JOHNSON_COOK

The Johnson-Cook material model is a strain and temperature sensitive plasticity model. It is sometimes used for materials with a large variation in the strain rate, and/or undergoing softening due to plastic heating.

REF Use reference geometry to initialize pressure

0: Off

1:On

LCID Load Curve Id defining pressure vs. volumetric strain

Field Comments






G Shear Modulus

Field Comments



E Young’s Modulus (for shell elements only)

PR Poisson’s Ratio (for shell elements only)

DTF Minimum Time step for Automatic Shell Element Deletion

VP Formulation for Rate Effects

0: Scale Yield Stress

1: ViscoPlastic Formulation

RATEOP Optional forms of strain-rate term:

.EQ. 0: Log-Linear Johnson-Cook (default)

.EQ. 1: Log-Quadratic Huh-Kang (2 parameters)

.EQ. 2: Exponential Allen-Rule_jones

.EQ. 3: Exponential Cowper-Symonds (2 parameters)

A, B, N, C, M Constants to define the flow stress equation

TM Melt Temperature

TR Room Temperature

EPSO Effective Plastic Strain Rate depends on Time Unit

CP Specific Heat

PC Pressure Cutoff (Pmin< 0.0)

SPALL Spall Type


1: P >= PC



IT Plastic Strain Iteration

0: No Iteration

1: Accurative Iteration Solution

Di Failure Parameters

C2/P Optional strain-rate parameter for Huh-Kang (C2), or Cowper-Symonds (P) forms.

Field Comments

Materials58


MAT_PSEUDO_TENSOR

This material model is used to define the properties a pseudo-tensor material model. This has been used to analyze buried steel reinforced concrete structures subjected to impulsive loadings.

Field Comments






G Shear Modulus

PR Poisson’s Ratio

SIGF Tension Cutoff (Maximum Principal Stress at failure)

A0 Cohesion

A1, A2 Pressure Hardening Coefficients

A0F Cohesion for failed material

A1F Pressure hardening coefficient for failed material

B1 Damage Scaling Factor

PER Percent Reinforcement




MAT_ORIENTED_CRACK

Defines the properties of brittle materials failing due to large tensile stresses.

ER Young’s Modulus for Reinforcement

PRR Poisson’s Ratio for Reinforcement

SIGY Initial Yield Stress

ETAN Tangent Modulus/Plastic Hardening Modulus

LCP Load Curve Id defining rate sensitivity for principal material

LCR Load Curve Id defining rate sensitivity for reinforcement

LCID Load Curve defining Yield Stress (or scale factor) vs. effective plastic strains, damages, or pressures

Field Comments






E Young’s Modulus


SIGY Yield Stress


FS Fracture Stress

PRF Fracture Pressure

Field Comments


Materials60


MAT_STRAIN_RATE_DEPENDENT_PLASTICITY

Defines the properties of a strain rate dependent material.

Field Comments






E Young’s Modulus




1: Viscoplastic Formulation

LC1 Load Curve Id for Yield Stress σ0 vs. effective strain rate

ETAN Tangent Modulus

LC2 Load Curve Id for Young’s Modulus vs. effective strain rate

LC3 Load Curve Id for Tangent Modulus vs. effective strain rate

LC4 Load Curve Id for von Mises stress at failure vs. effective strain rate

TDEL Time Step Size for Automatic Element Deletion (shell elements only)

RDEF Redefinition of failure curve

1: Effective plastic strain

2: Maximum principal stress




MAT_ORTHOTROPIC_THERMAL

Defines the properties of a linear elastic material with temperature dependent orthotropic properties.

Field Comments






EA, EB, EC Young’s Moduli in the A, B and C direction

PRBA, PRCA, PRCB Poisson’s Ratio in the ba, ca and cb directions

GAB, GBC, GCA Shear Moduli in the ab, bc and ca directions

AA, AB, AC Coefficients of Thermal Expansion in the a, b, and c directions


Materials62


AOPT Material Axes option

0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of local c- and a- axes.)

1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only.

2: Globally orthotropic with material axis determined by3 vectors below.

3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the center line axis. This option is for solid elements only.

XP X-coordinate of point p for AOPT=1

YP Y-coordinate of point p for AOPT=1

ZP Z-coordinate of point p for AOPT=1

Ai Component of Vector a, for AOPT=2

Vi Component of Vector v, for AOPT=3

Di Component of Vector d, for AOPT=2

BETA Material Angle (Degrees), for AOPT = 3

REF Use Reference Geometry to initialize stress tensor (0 = off; 1 = on)

Field Comments



MAT_COMPOSITE_DAMAGE

Defines the properties of an orthrotropic material with optional brittle failure for composites.

Field Comments






EA, EB, EC Young’s Moduli in the A, B and C direction



KF Bulk Modulus of failed material

Materials64



0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.)




4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.







BETA Material Angle

SC Shear Strength, ab plane

XT Longitudinal Tensile Strength, a-axis

YT Transverse Tensile Strength, b-axis

YC Transverse Compression Strength, b-axis

ALPH Shear Stress Parameter for nonlinear term (0- 0.5)

SN Normal Tensile Strength (solid elements only)

SYX Transverse Shear Strength (solid elements only)

SZX Transverse Shear Strength (solid elements only)

Field Comments



MAT_TEMPERATURE_DEPENDENT_ORTHOTROPIC

Defines the properties of an orthotropic elastic material with arbitrary temperature dependency.

Field Comments






Materials66







REF Use Reference Geometry to initialize stress tensor (0 = off; 1 = on)

MACF Material axes change flag for brick element:

=1 No Change; = 2 switch mateial axes a and b

=3 switch material axes a and c ; =4 switch material axes b and c







BETA Material Angle

EA_LC, EB_LC, EC_LC

Load curve defining Young’s Moduli in the a, b and c directions, respecively, vs. Temperature

PRBA_LC Load curve defining Poisson’s Ratios in the ba directionsvs. Temperature

PRCA_LC Load curve defining Poisson’s Ratios in the ca directionsvs. Temperature

PRCB_LC Load curve defining Poisson’s Ratios in the cb directionsvs. Temperature

Field Comments



MAT_GEOLOGIC_CAP_MODEL

Defines the properties for geomechanical problems or materials like concrete.

AA_LC, AB_LC, AC_LC

Load curves defining Coefficients of Thermal Expansion in the a, b, and c directions, respectively, vs. Temperature

GAB_LC Load curve defining Shear modulus in the ab plane vs. Temperature

GBC_LC Load curve defining Shear modulus in the bc plane vs. Temperature

GCA_LC Load curve defining Shear modulus in the ca plane vs. Temperature

Field Comments






BULK Initial Bulk Modulus

G Initial Shear Modulus

ALPHA Failure Envelope Parameter

THETA Failure Envelope Linear coefficient

GAMMA Failure Envelope Exponential coefficient

BETA Failure Envelope Exponent

R Cap, surface axis ratio

Field Comments


Materials68


D Hardening law exponent

W Hardening law coefficient

X0 Hardening Law Exponent

C Kinematic Hardening Coefficient

N Kinematic Hardening Parameter

PLOT Plotting Flag for LS-Taurus

FTYPE Formulation Flag

1: Soil or concrete

2: Rock

VEC Vectorization Flag

0: Vectorized with a fixed number of iterations

1: Fully Iterative

TOFF Tension Cutoff

Field Comments



MAT_HONEYCOMB

Defines the properties for honeycomb and foam materials with real anisotropic behavior.

Field Comments






E Young’s Modulus


SIGY Yield Stress for fully compacted Honeycomb

VF Relative Volume at which Honeycomb is fully compacted

MU Material Viscosity Coefficient

BULK Bulk Viscosity Flag

0: Bulk Viscosity Not Used

1: Bulk Viscosity Active and MU=0

LCA Load Curve Id for (Sigma_aa vs. either Relative Volume or Volumetric Strain

LCB Load Curve Id for (Sigma_bb vs. either Relative Volume or Volumetric Strain (Default LCB = LCA)

Materials70


LCC Load Curve Id for (Sigma_cc vs. either Relative Volume or Volumetric Strain (Default LCC = LCA)

LCS Load Curve Id for (shear stress vs. either Relative Volume or Volumetric Strain (Default LCS = LCA)

LCAB Load Curve Id for (Sigma_ab vs. either Relative Volume or Volumetric Strain (Default LCAB = LCS)

LCBC Load Curve Id for (Sigma_bc vs. either Relative Volume or Volumetric Strain (Default LCBC = LCS)

LCCA Load Curve Id for (Sigma_ca vs. either Relative Volume or Volumetric Strain (Default LCCA = LCS)

LCSR Load Curve Id for strain rate effects defining the scale factor vs. strain rate. The curves defined above are scaled using this curve.

EAAU, EBBU, ECCU Elastic Moduli in uncompressed configuration in aa, bb, and cc directions

GABU, GBCU, GCAU Shear Moduli in uncompressed configuration in ab, bc, and ca planes





XP x-coordinate of point p, for AOPT = 1

YP y-coordinate of point p, for AOPT = 1

ZP z-coordinate of point p, for AOPT = 1

Ai Component of vector a, for AOPT = 2

Di Component of vector d, for AOPT = 2

TSEF Tensile Strain at Element Failure

SSEF Shear Strain at Element Failure

Field Comments



MAT_RESULTANT_PLASTICITY

Defines a resultant formulation material model, including elastoplastic behavior.for beam and shell elements,


Field Comments






E Young’s Modulus


SIGY Yield Stress

ETAN Plastic Hardening Modulus (shell elements only)


Materials72

MAT_FORCE_LIMITED

This material model allows the simulation of plastic hinge formation at the ends of a beam, using a curve definition (for Belytschko-Schwer beam only).

Field Comments






E Young’s Modulus


DF Damping Factor

AOPT Axial Load Curve Option

0: Force vs. Strain

1: Force vs. Change in Length

M1, M2,,,,, M8 Applied end moment for force vs. strain/ or change in length curve. A minimum of one, and a maximum of eight must be defined.

LC1, LC2, ..., LC8 Load Curve Ids applied end moment



MAT_SHAPE_MEMORY

Defines the superplastic response present in shape memory alloys (SMA).

LPSi Load Curve Id for plastic moment vs. rotation about s-axis at node i

SFSi Scale factor, plastic moment vs. rotation about s- axis at node i

YMSi Yield moment about s- axis at node i for interaction calculations

LPTi Load Curve Id for plastic moment vs. rotation about t-axis at node i

SFTi Scale factor, plastic moment vs. rotation about t- axis at node i

YMTi Yield moment about t- axis at node i for interaction calculations

LPR Load Curve Id for plastic torsional moment vs. rotation

SFR Scale factor for plastic torsional moment vs. rotation

YMR Torsional yield moment for interaction calculations

Field Comments






E Young’s Modulus


SIG_ASS Starting value for the forward phase transformation

Field Comments


Materials74


MAT_FRAZER_NASH_RUBBER_MODEL

Defines rubber from uniaxial test data.

SIG_ASF Final value for the forward phase transformation

SIG_SAS Starting value for the reverse phase transformations

SIG_SAF Final value for the reverse phase transformation

EPSL Recoverable strain or maximum residual strain

ALPHA Parameter Measuring the difference between material response in tension and compression

YMRT Young’s Modulus for Martensite

LC_ASS Load Curve Id for Starting value of forward phase transformation

LC_ASF Load Curve Id for Final value of forward phase transformation

LC_SAS Load Curve Id for Starting value of reverse phase transformations

LC_SAF Load Curve Id for Final value of reverse phase transformation

Field Comments





Field Comments






C100, C200, C300, C400, C110, C210, C010, C020

Strain Energy Parameters

EXIT Exit option of strain limit

0: Stop if limit exceeds

1: Continue even if limit exceeds

EMAX Maximum Strain Limit

EMIN Minimum Strain Limit

REF Use Reference Geometry to initialize stress tensor

0: Off

1: On

SGL Specimen Gauge Length

SW Specimen Width

ST Specimen Thickness

LCID Load Curve Id defining Force vs. Actual Change in gauge Length

Field Comments


Materials76

MAT_LAMINATED_GLASS

Defines layered glass including polymeric layers.

Field Comments






EG Young’s Modulus for Glass

PRG Poisson’s Ratio for Glass

SYG Yield Strength for Glass

ETG Plastic Hardening Modulus for Glass

EFG Plastic Strain at Failure for Glass

EP Young’s Modulus for Polymer

PRP Poisson’s Ratio for Polymer

SYP Yield Strength for Polymer

ETP Plastic Hardening Modulus for Polymer

NUM_RFS Number of Integration Points of Material

F1, F2,, ..., FN Integration Point Material

Fi = 0: glass; Fi = 1: polymer



MAT_BARLAT_ANISOTROPIC_PLASTICITY

Defines the properties of an anisotropic material behavior during forming processes.

Field Comments






E Young’s Modulus


K Strength Coefficient

E0 Strain corresponding to initial yield

N Hardening exponent for yield strength

M Flow potential exponent in Barlat’s model

A, B, C, F, G, H Anisotropic Coefficients in Barlat’s model

LCID Load Curve Id defining effective Stress vs. effective Plastic Strain


Materials78






3: Locally orthotropic with material axis determined by offsetting the material axes by an angle, OFFANG, from a line defined by the cross product of the vector v with the normal to the plane of a shell element, or mid surface of a brick element.

BETA Offset angle (for AOPT = 3)










Field Comments



MAT_BARLAT_YLD96

Defines the properties of an anisotropic material behavior during forming processes, especially for aluminum alloys (only for shell elements only).

Field Comments






E Young’s Modulus


K Strength Coefficient

E0 Strain corresponding to initial yield

N Hardening exponent for yield strength

ESRO εSRO, in power law rate sensitivity

M Exponent, m for strain rate effects

Materials80


HARD Hardening option

<0: Absolute value defines the Load Curve Id

1:Powerlaw

2: Voce

A Flow Potential Exponent

Ci Equation parameters

AX Equation parameter

AY Equation Parameter

AZ0 Equation Parameter

AZ1 Equation Parameter





3: Locally orthotropic with material axis determined by offsetting the material axes by an angle, OFFANG, from a line defined by the cross product of the vector v with the normal to the plane of the element.

OFFANG Offset Angle for AOPT = 3

blank1, blank2, blank3 Blank Fields




Field Comments



MAT_FABRIC

Defines the properties for airbag materials.

Field Comments






EA Young’s Modulus, Longitudinal Direction

EB Young’s Modulus, Transverse Direction

EC Young’s Modulus, Normal Direction

PRBA, PRCA, PRCB Poisson’s Ratio in ba, ca, and cb directions

GAB, GBC, BCA Shear Moduli in ab., bc, and ca directions

Materials82

CSE Compressive Stress Elimination Option

0: Don’t Eliminate

1: Eliminate

EL Young’s Modulus for Elastic Liner

PRL Poisson’s Ratio for Elastic Liner

LRATIO Ratio of linear thickness to total fabric thickness

DAMP Rayleigh Damping Coefficient






FLC Fabric Leakage coefficient

FAC Fabric Area Coefficient

ELA Effective Leakage Area for blocked fabric

LNRC Liner Compression Flag

0: Off

1:On

Field Comments


FORM Flag to modify Membrane Formulation for fabric material:

0: default

1: in variant Local Coordinate System

2: Green-Lagrange strain formulation

3: Large Strain with nonorthogonal material angles

4: Large Strainwith nonorthogonal material angles, and nonlinear material stress strain behavior. Define optional Load Curve Ids.

FVOPT Fabric Venting Option

1: Wang-Nefske formulas for venting, through orifice, with no blockage.

2: Wang-Nefske formulas for venting through orifice, with blockage.

3: Graefe, Krummheurer, and Siejak [1990] Leakage formulas with no blockage.

4: Graefe, Krummheurer, and Siejak [1990] Leakage formulas with blockage.

5: Leakage formulas based on flow through a porous media, with no blockage.

6: Leakage formulas based on flow through a porous media, with blockage.

TSRFAC Tensile Stress Cutoff Reduction factor





BETA Material Angle (Degrees), for AOPT=3

LCA Load Curve Id for Stress vs. Strain along the a- axis

LCB Load Curve Id for Stress vs. Strain along the b- axis

LCAB Load Curve Id for Stress vs. Strain in the ab plane

LCUA Unload/Reload Curve Id for Stress vs. Strain along a- axis

LCUB Unload/Reload Curve Id for Stress vs. Strain along b- axis

LCUAB Unload/Reload Curve Id for Stress vs. Strain in the ab plane

LC_FLC Load Curve Id for Fabric Leakage Coefficient

Field Comments

Materials84


MAT_PLASTIC_GREEN-NAGHDI_RATE

This model is available for brick elements only. It is similar to MAT_PLASTIC_KINEMATIC, but uses the Green-Naghdi Rate formulation for the stress update.


LC_FAC Load Curve Id for Fabric Area Coefficient

LC_ELA Load Curve Id for Effective Leakage Area for blocked fabric

LC_TSR Load Curve Id for Tensile Stress Cutoff Reduction factor vs. Time

Field Comments






E Young’s Modulus


SIGY Yield Strength


SRC Strain Rate Parameter

SRP Strain Rate Parameter

BETA Hardening Parameter

Field Comments




MAT_3-PARAMETER_BARLAT

This material model is designed for modeling sheets with anisotropic materials under plane stress conditions.

Field Comments






E Young’s Modulus


HR Hardening Rule

1: Linear

2: Exponential

3: Load Curve

P1, P2 Material Parameters

Materials86


ITER Iteration Flag

0: Fully iterative

1: Fixed to 3 iterations

M Exponent in Barlat’s yield surface

R00, R45, R90 Lankford Parameters

LCID Load Curve Id for hardening rule

Epsilon_0 ε0 for determining initial yield stress for exponential hardening

SPI Parameter to redefine ε0














Field Comments



MAT_TRANS_ANISO_ELASPLASTIC

Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered.


Field Comments






E Young’s Modulus


SIGY Yield Stress


R Anisotropic Hardening Parameter

HLCID Load Curve Id for Effective Yield Stress vs. Effective Plastic Strain


Materials88

MAT_TRANS_ANISO_ELASPLASTIC_ECHANGE



Field Comments






E Young’s Modulus


SIGY Yield Stress


R Anisotropic Hardening Parameter

HLCID Load Curve Id for Effective Yield Stress vs. Effective Plastic Strain

IDSCALE Load curve Id defining the scale factor for Young’s modulus change with respect to effective strain. Note: if EA, and COE are defined, this curve is not necessary.

EA, COE Coefficients (EA and ζ) defining Young’s modulus with respect to the effective strain. Note: if EA, and COE are defined, this curve is not necessary.



MAT_BLATZ-KO_FOAM

Defines the properties for rubber like foams of polyurethane. It is a simple one parameter model with a fixed Poisson’s ratio of 0.25.


Field Comments






G Shear Modulus



Materials90

MAT_FLD_TRANSVERSELY_ANISOTROPIC



Field Comments






E Young’s Modulus


SIGY Yield Stress


R Anisotropic Hardening Modulus

HLCID Load Curve Id defining Effective Yield Stress vs. Effective Plastic Strain

LCIDFLD Load Curve Id defining the Forming Limit Diagram (major vs. minor strain)



MAT_NONLINEAR_ORTHOTROPIC

Defines an orthotropic nonlinear elastic material based on a finite strain formulation with initial geometry as the reference. Optional failure and stiffness properties are available.

Field Comments






EAA, EBB, ECC Young’s Modulus in the A, B and C directions


GAB, GBC, GCA Shear Modulus in the ab, bc and ca directions

DT Temperature increment for stress stabilization

TRAMP Time to ramp up to the final temperature

ALPHA Thermal expansion coefficient

LCIDA, LCIDB, LCIDC Load Curve Id for nominal stress vs. nominal strain in the a- , b-, and c-axes

EFAIL Failure Strain

Materials92


DTFAIL Timestep size criteria for element erosion

CDAMP Damping Coefficient











LCIDAB, LCIDBC, LCIDCA

Load Curve Id for nominal shear stress vs. nominal shear strain in the ab, bc, and ca plane

Field Comments



MAT_BAMMAN

Defines a material with temperature and rate dependent plasticity.


Field Comments






E Young’s Modulus


T Initial Temperature

HC Heat Generation Coefficient

Ci Input parameters

Ai Initial value of state variable i

KAPPA Initial value of internal state variable 6 (κ)


Materials94

MAT_BAMMAN_DAMAGE

Defines a material with temperature and rate dependent plasticity including damage in the modeling.

Field Comments






E Young’s Modulus




Ci Input parameter

Ai Initial value of state variable i

N Exponent in damage evaluation

D0 Initial Damage (porosity)

FS Failure Strain for Erosion



MAT_CLOSED_CELL_FOAM

Defines a low density, closed polyurethane foam for simulating impact limiters in automotive applications.


Field Comments






E Young’s Modulus


A, B, C Factors a, b, and c for Yield Stress definition

P0 Initial Foam Pressure

PHI Ratio of Foam to Polymer Density

GAMA0 Initial Volumetric Strain

LCID Load Curve Id defining vonMises Stress vs. Volumetric Strain



Materials96

MAT_ENHANCED_COMPOSITE_DAMAGE

Defines the properties of an orthrotropic material with optional brittle failure for composites. This is an enhanced version of MAT_COMPOSITE_DAMAGE (MAT_022).

Field Comments








EC Young’s Modulus, Normal Direction (NOT used)

PRBA, PRCA, PRCB Poisson’s Ratio in the ba, ca, and cb planes (PRCA, PRCB NOT used)

GAB, GBC, GCA Shear Modulus in the ab, bc, and ca planes

KF Bulk Modulus of failed material (NOT used)







bl1, bl2, bl3 Blank Fields

Ai Components of Vector a, for AOPT=2

MANGLE Material Angle (Degrees), for AOPT=3

Vi Components of Vector v, for AOPT=3


DFAILM Maximum Strain for matrix straining in tension/compression

DFAILS Maximum shear strain

TFAIL Timestep size criteria for element deletion

ALPH Shear Stress Parameter for NonLinear Term

SOFT Softening Reduction Factor

FBRT Softening of fiber Tensile Strength

YCFAC Reduction Factor for compressive fiber strength, after matrix failure

DFAILT Maximum Strain for fiber in tension

DFAILC Maximum Strain for fiber in compression

EFS Effective Failure Strain

XC Longitudinal Compression Strength

XT Longitudinal Tensile Strength

YC Transverse Compression Strength

YT Transverse Tensile Strength


Field Comments

Materials98


CRIT Failure Criteria (Material Number)

54: Chang matrix failure criterion

55: Tsai-Wu matrix failure criterion

BETA Weight Factor for Shear term in tensile fiber mode

Field Comments



MAT_LAMINATED_COMPOSITE_FABRIC

Defines a composite material with unidirectional layers, complete laminates and woven fabrics (for shell elements only).

Field Comments








EC Young’s Modulus, Normal Direction (NOT used)

PRBA Poisson’s Ratio in BA direction

Materials100

TAU1 Stress limit of first slightly nonlinear part of Shear Stress vs. Shear Strain curve

GAMMA1 Strain limit of first slightly nonlinear part of Shear Stress vs. Shear Strain curve

SLIMT1 Factor to determine the minimum Stress Limit after Stress Maximum (fiber Tension)

SLIMC1 Factor to determine the minimum Stress Limit after Stress Maximum (fiber Compression)

SLIMS Factor to determine the minimum Stress Limit after Stress Maximum (Shear)






TSIZE Time step size for Automatic Element Deletion

ERODS Maximum Element Strain for Element Layer Failure

SOFT Softening Reduction Factor in Crash front

FS Failure Surface Type

1: Smooth surface Failure with Quadratic criteria for both fiber and transverse directions

0: Smooth surface Failure with Quadratic criteria for transverse direction, with a limiting value in the fiber direction

-1: Faceted Failure surface



Field Comments








E11C Strain at Longitudinal Compression Strength, a-axis

E11T Strain at Longitudinal Tensile Strength, a-axis

E22C Strain at Transverse Compression Strength, b-axis

E22T Strain at Transverse Tensile Strength, b-axis

GMS Strain at Shear Strength, ab plane






Field Comments


Materials102

MAT_COMPOSITE_FAILURE_SHELL_MODEL

Defines the properties of a composite material with failure properties (for shell elements only).

Field Comments









PRBA, PRCA< PRCB Poisson’s Ratio in ba, ca and cb directions

GAB, GBC, GCA Shear Moduli in ab, bc and ca directions




AOPT 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.)




MAFLAG Material Axes Flag (NOT active for shells)

XP X-coordinate of point p for AOPT=1 and 4

YP Y-coordinate of point p for AOPT=1 and 4

ZP Z-coordinate of point p for AOPT=1and 4


Vi Component of Vector v, for AOPT=3, and 4



TSIZE Time step size for Automatic Element Deletion

ALP Nonlinear stress parameter

SOFT Softening Reduction Factor in Crashfront

FBRT Softening of fiber Tensile Strength

SR Reduction Factor

SF Softening Factor






Field Comments


Materials104

MAT_COMPOSITE_FAILURE_SOLID_MODEL

Defines the properties of a composite material with failure properties (for solid elements only).

Field Comments









PRBA, PRCA< PRCB Poisson’s Ratio in ba, ca and cb directions

GAB, GBC, GCA Shear Moduli in ab, bc and ca directions









MAFLAG Material Axes Change Flag

1: Default

2: Switch Axes a and b

3: Switch Axes a and c

XP X-coordinate of point p for AOPT=1 and 4

YP Y-coordinate of point p for AOPT=1 and 4

ZP Z-coordinate of point p for AOPT=1and 4


Vi Component of Vector v, for AOPT=3, and 4



SBA In Plane Shear Strength

SCA Transverse Shear Strength

SCB Transverse Shear Strength

XXC Longitudinal Compression Strength, x-axis

YYC Transverse Compression Strength, b-axis

Field Comments

Materials106


MAT_ELASTIC_WITH_VISCOSITY

Simulates the forming of glass products at high temperatures.

ZZC Normal Compression Strength, c-axis

XXT Longitudinal Tensile Strength, x-axis

YYT Transverse Tensile Strength, b-axis

ZZT Normal Tensile Strength, c-axis

Field Comments





Field Comments




MAT_ELASTIC_WITH_VISCOSITY_CURVE

Simulates the forming of glass products at high temperatures.Load curves are used to represent the temperature dependence of Poisson’s ratio, Young’s modulus, the coefficient of thermal expansion, and the viscosity.


V0

A, B, C Viscosity coefficients

LCID Load Curve Id defining factor for viscosity vs. temperature

PRi

Ti Temperatures

Vi Corresponding Viscosity coefficients

Ei Corresponding Young’s moduli coefficients

ALPHAi Corresponding thermal expansion coefficients

Field Comments






V0

Field Comments


Materials108


MAT_KELVIN-MAXWELL_VISCOELASTIC

A classic Kelvin-Maxwell material model for modeling viscoelastic bodies, like foams.

A, B, C Viscosity coefficients

LCID Load Curve Id defining factor for viscosity vs. temperature

PR_LC Load curve defining Poisson’s ratio as a function of temperature

YM_LC Load curve defining Young’s modulus as a function of temperature

A_LC Load curve defining the coefficient of thermal expansion as a function of temperature

V_LC Load curve defining the viscosity as a function of temperature

V_LOG Falg for the form of V_LC. If V_LOg =1, the value specified in V_LC is the natural logarithm of the viscosity. If V_LOg =0, the value is the viscosity.

Field Comments






BULK Bulk Modulus (elastic)

GO Short time Shear Modulus

GI Long time Shear Modulus

DC Maxwell decay constant or Kelvin relaxation constant

Field Comments




MAT_VISCOUS_FOAM

A material to represent the Confor Foam on the ribs of EuroSID side impact dummy (valid only for solid elements under compressive load).

FO Formulation option

0: Maxwell

1: Kelvin

SO Strain output option

0: Maximum principal Strain occurring during the calculation

1: Maximum magnitude of principal Strain occurring during the calculation

2: Maximum Effective Strain occurring during the calculation

Field Comments






E1 Initial Young’s Modulus

N1 Exponent in power law for Young’s Modulus

V2 Viscous Coefficient

E2 Elastic Modulus for viscosity

Field Comments


Materials110


MAT_CRUSHABLE_FOAM

A material model for modeling crushable foam with optional damping and tension cutoff.


N2 Exponent in power law for viscosity


Field Comments






E Young’s Modulus


LCID Load Curve Id defining Yield Stress vs. Volumetric Strain

TSC Tensile Stress Cutoff

DAMP Rate sensitivity via damping coefficient

Field Comments




MAT_RATE_SENSITIVE_POWERLAW_PLASTICITY

A strain rate sensitive elasto-plastic material model with a power law hardening.

Field Comments






E Young’s Modulus


K Material Constant

M Strain Hardening Coefficient

N Strain Rate Sensitivity Coefficient

E0 Initial Strain Rate




EPSO Factor to Normalize Strain (Time Units)

1: Seconds

1e-006 : Milliseconds

1e-006 : Microseconds

Materials112


MAT_MODIFIED_ZERILLI_ARMSTRONG

A rate and temperature sensitive plasticity material model, sometimes used in ordinance design calculations.

LCID_K Load Curve Id defining material constant K vs. Effective Plastic Strain

LCID_M Load Curve Id defining material constant M vs. Effective Plastic Strain

LCID_N Load Curve Id defining material constant N vs. Effective Plastic Strain

Field Comments






G Shear Modulus

E0 Factor to normalize strain rate

N Exponent for bcc metal

TROOM Room Temperature

PC Pressure Cutoff

Field Comments




SPALL Spall Type

1: Minimum Pressure Limit

2: Maximum Principal Stress

3: Minimum Pressure Cutoff

Ci Coefficients for flow stress

EFAIL Failure Strain for Erosion




Bi Coefficients for polynomial representation of temperature dependency of flow stress yield

Gi Coefficient for defining Heat Capacity and temperature dependency of Heat Capacity

BULK Bulk Modulus (for shell elements only)

Field Comments


Materials114

MAT_LINEAR_ELASTIC_DISCRETE_BEAM

A material model for linear elastic beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam.


Field Comments






TKR, TKS, TKT Translational Stiffness along local ar-, s-, and t- axes respectively

RKR, RKS, RKT Rotational Stiffness about local r-, s-, and t- axes respectively

TDR, TDS, TDT Translational viscous damping along local r-, s-, and t- axes respectively

RDR, RDS, RDT Rotational viscous damping about local r-, s-, and t- axes respectively

FOR, FOS, FOT Pre-load forces in r-, s- and t-directions repectively (optional)

MOR, MOS, MOT Pre-load moments in r-, s- and t-directions repectively (optional)



MAT_NONLINEAR_ELASTIC_DISCRETE_BEAM

A material model for nonlinear elastic and nonlinear viscous beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam.


Field Comments






LCIDTR, LCIDTS, LCIDTT

Load Curve Id defining Translational Force along the r-, s-, and t- axes vs. Translational Displacement

LCIDRR, LCIDRS, LCIDRT

Load Curve Id defining Rotational Moment about the r-, s-, and t- axes vs. Rotational Displacement

LCIDTDR, LCIDTDS, LCIDTDT

Load Curve Id defining Translational Damping Force along the r-, s-, and t- axes vs. Translational Velocity

LCIDRDR, LCIDRDS, LCIDRDT

Load Curve Id defining Rotational Damping Force the r-, s-, and t- axes axis vs. Rotational Velocity




Materials116

MAT_NONLINEAR_PLASTIC_DISCRETE_BEAM

A a material model for nonlinear elastoplastic, linear viscous behavior of beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam.

Field Comments






TKR, TKS, TKT Translational Stiffness along local r-, s-, and t- axes respectively

RKR, RKS, RKT Rotational Stiffness about local r-, s-, and t- axes respectively

TDR, TDS, TDT Translational viscous damping along local r-, s-, and t- axes respectively

RDR, RDS, RDT Rotational viscous damping about local r-, s-, and t- axes respectively

LCPDR, LCPDS, LCPDT

Load Curve Id for Yield Force vs. Plastic Displacement along local r-, s-, and t- axes respectively

LCPMR, LCPMS, LCPMT

Load Curve Id for Yield Moment vs. Plastic Rotation about local r-, s-, and t- axes respectively



MAT_SID_DAMPER_DISCRETE_BEAM

A material model for side impact dummy, using a damper that is not adequately taken care of by the nonlinear force versus relative velocity curves.

FFAILR, FAILS, FAILT Failure Parameters corresponding to Force Fr, Fs, Ft

MFAILR, MFAILS, MFAILT

Failure Parameters corresponding to Moment Mr, Ms, Mt

UFAILR, UFAILS, UFAILT

Failure Parameters corresponding to Displacement Ur, Us, Ut

TFAILR, TFAILS, TFAILT

Failure Parameters corresponding to Rotation θr, θs, θt



Field Comments





Field Comments


Materials118



ST Piston Stroke

D Piston Diameter

R Orifice Radius

H Orifice Controller Position

K Damping Constant

C Discharge Coefficient

C3 Coefficient for fluid inertia term

STF Stiffness Coefficient (piston bottom out)

RHOF Fluid Density

C1 Coefficient of linear velocity term

C2 Coefficient of quadratic velocity term

LCIDF Load Curve Id defining Force vs. Piston Displacement

LCIDD Load Curve Id defining Damping Coefficient vs. Piston Displacement

S0 Initial Displacement

NUM_RFS Number of Orifice Location

ORFLOCi Orifice Location of the i-th orifice, relative to the fix end

ORFRADi Orifice Radius of the i-th orifice

SFi Scale factor on calculated force for the i-th orifice

DCi Linear viscous damping coefficient (after damper bottoms out in tension or compression) for the i-th orifice

Field Comments



MAT_HYDRAULIC_GAS_DAMPER_DISCRETE_BEAM

A special element that represents a combined hydraulic and gas-filled damper with a variable orifice coefficient. This material can only be used as a discrete beam element.


Field Comments






C0 Length of Gas Column

N Adiabatic constant

P0 Initial gas Pressure

PA Atmospheric Pressure

AP Piston Cross-Section Area

KH Hydraulic Constant

LCID Load Curve Id Defining Orifice Area vs. Element Deletion

FR Return factor on orifice force

SCLF Scale factor on Force

CLEAR Clearance


Materials120

MAT_CONCRETE_DAMAGE

A material model for analyzing buried steel reinforced concrete structure with impulsive loading.

Field Comments






E Young’s Modulus


SIGF Maximum principal Stress at Failure

A0, A0Y Cohesion and Cohesion for Yield



A1, A2 Pressure Hardening Coefficients

A1Y, A2Y Pressure Hardening Coefficients for yield limit

A1F, A2F Pressure Hardening Coefficients Failed Material)

B1 Damage Scaling Factor

B2 Damage Scaling Facto for uniaxial tensile path

B3 Damage Scaling Facto for triaxial tensile path

PER Percent Reinforcement

ER Young’s Modulus for Reinforcement

PRR Poisson’s Ration for Reinforcement


ETAN Tangent Modulus/Plastic hardening Modulus

LCP Load Curve Id giving rate sensitivity for principal material

LCR Load Curve Id giving rate sensitivity for reinforcement

LAMBDAi Tabulated Damage functions

ETAi Tabulated Scale Factors

Field Comments


Materials122

MAT_LOW_DENSITY_VISCOUS_FOAM

A material model for low density urethane foam with high compressibility, and with rate sensitivity characterized by a relaxation curve.

Field Comments






E Young’s Modulus

LCID Load Curve Id for nominal Stress vs. Strain

TC Tension Cutoff Stress

HU Hysteretic Unloading Factor between 0 to 1

BETA Decay constant to model creep in unloading

DAMP Viscous coefficient

SHAPE Shape factor for unloading

FAIL Failure Option after Cutoff Stress

1: Tensile stress remains at cutoff value

2: Tensile stress is reset to zero



MAT_ELASTIC_SPRING_DISCRETE_BEAM

A model for elastic springs with damping to be combined and represented with a discrete beam element.

BVFLAG Bulk Viscosity activation Flag

0: No

1: Active

KCON Stiffness coefficient for contact interface stiffness

LCID2 Load Curve Id of relaxation curve

BSTART Fit Parameter

TRAMP Optional ramp time for loading

NV Number of terms in fit

NUM_RFS Number of viscoelastic constants

GI1 Optional relaxation modulus for rate effect

BETAI1 Optional decay constant


0: Off

1: On

Field Comments



Field Comments


Materials124


MAT_BILKHU/DUBOIS_FOAM

A material model to simulate isotropic crushable foams using uniaxial and triaxial test data.




E Young’s Modulus

K Elastic loading and unloading stiffness

F0 Optional initial force

D Optional viscous damping coefficient

CDF Compressive displacement at failure

TDF Tensile displacement at failure

FLCID Load Curve Id defining Yield Force vs. Deflection for nonlinear behavior

HLCID Load Curve Id defining Force vs. Relative Velocity for nonlinear behavior

Ci Damping Coefficients

DLE Scale factor for time unit

GLCID Load Curve Id defining Scale Factor vs. Deflection for Load Curve Id (HLCID)

Field Comments



Field Comments







YM Young’s Modulus

LCPY Load Curve Id defining Yield Pressure vs. Volumetric Strain

LCUYS Load Curve Id defining uniaxial Yield Stress vs. Volumetric Strain

VC Viscous Damping Coefficient

PC Pressure Cutoff

VPC Variable Pressure Cutoff as a fraction of pressure yield value

TC Tension Cutoff for uniaxial tensile stress

VTC Variable Tension Cutoff as a fraction of uniaxial compressive yield strength

LCRATE Load Curve Id defining Scale Factor for the previous yield curves, dependent upon the volumetric strain vs. Volumetric plastic Strain

PR Poisson coefficient applying to both elastic and plastic deformations

KCON Stiffness coefficient for contact interface stiffness. If undefined, one third of Young’s Modulus (YM) is used..

ISFLG Tensile response flag (active only if negative abscissa are present in the load curve LCUYS).

.EQ. 0: load curve abscissa in tensile region correspond to volumetric strain.

.EQ. 1: load curve abscissa in tensile region correspond to effective strain.

Field Comments


Materials126

MAT_GENERAL_VISCOELASTIC

A general viscoelastic Maxwell model used for modeling dense continuum rubber and solid explosives.

Field Comments






BULK Elastic Bulk Modulus

PCF Tensile Pressure elimination flag (for solid elements only)

1: yes (Tensile Pressure reset to zero)

0: no (Tensile Pressure NOT reset to zero)

EF Elastic Flag

1: Elastic layer

0: Viscoelastic layer

LCID Load Curve Id for deviatoric behavior

NT Number of terms in shear fit

BSTART Parameter for resetting the exponents in the Relaxation Curve

TRAMP Optional Time ramp for loading

LCIDK Load Curve ID defining the bulk behavior



MAT_HYPERELASTIC_RUBBER

A general hyperelastic rubber material model, combined optionally with linear viscoelasticity.

NTK Number of terms in bulk

BSTARTK Fit Parameter for bulk

TRAMPK Optional ramp time for bulk loading

NUM_RFS number of viscoelastic constants

GIi Optional shear relaxation modulus for the i-th term

BETAIi Optional shear Decay Constant for the i-th term

KIi Optional bulk Relaxation Modulus for the i-th term

BETAKIi Optional bulk Decay Constant for the i-th term

Field Comments




Field Comments


Materials128





N Constants to solve for

1: Solve for C10, C01

2: Solve for C10, C01, C11, C20, C02

3: Solve for All constants (C10, C01, C11, C20, C02, and C30)

NV Number of Prony series terms in fit

G Shear Modulus

SIGF Limit stress for frequency independent, frictional, Damping

SGL Specimen gauge length

SW Specimen Width


LCID1 Load Curve Id defining Force vs. Actual Change in gauge Length

DATA Type of experimental data

0:Uniaxial




Ci Material Constants


GIi Optional Shear Relaxation Modulus for the i-th term

BETAIi Optional Decay Constants for the i-th term

Field Comments



MAT_OGDEN_RUBBER

An Ogden rubber material model, combined optionally with linear viscoelasticity.

Field Comments







N Order to fit the Ogden model

NV Number of Prony series terms in fit

G Shear Modulus

SIGF Limit stress for frequency independent, frictional, Damping

SGL Specimen gauge length

SW Specimen Width


Materials130


MAT_SOIL_CONCRETE

An efficient soil and concrete material model.

LCID1 Load Curve Id defining Force vs. Actual Change in Length

DATA Type of experimental data

1:Uniaxial

2:Biaxial




MUi i-th Shear Modulus

ALPHAi i-th Exponent


GIi i-th Optional Shear Relaxation Modulus

BETAIi i-th Optional Decay Constant

Field Comments






G Shear Modulus

Field Comments




K Bulk Modulus

LCPV Load Curve Id defining Pressure vs. Volumetric Strain

LCYP Load Curve Id defining von Mises Stress vs. Pressure

LCFP Load Curve Id defining Plastic Strain at which fracture starts vs. Pressure

LCRP Load Curve Id defining Plastic Strain at which residual strength is released vs. Pressure

PC Pressure Cutoff

OUT Output option for plastic strain

0: Volumetric

1: Deviatoric

B Residual strength factor after cracking

FAIL Failure flag

0: No

1: Element Erodes when Pressure reached failure pressure

2: No tension in element when Pressure reached failure pressure

Field Comments


Materials132

MAT_HYSTERETIC_SOIL

A nested surface material model with five superimposed layers of elasto-perfectly plastic material, each with its own elastic moduli and yield values.

Field Comments






K0 Bulk Modulus

P0 Pressure Cutoff

B Exponent for pressure sensitive moduli

A0, A1, A2 Yield Function Constants

DF Damping Factor

RP Reference Pressure

LCID Load Curve Id defining Shear Stress vs. Shear Strain

SCLF Scale Factor o apply on shear stress in LCID

DIL_A Dilation Parameter A

DIL_B Dilation Parameter B

DIL_C Dilation Parameter C

DIL_D Dilation Parameter D



MAT_RAMBERG_OSGOOD

A simple material model of shear behavior, and can be used for seismic analysis.

GAMi Shear Strains (if LCID is zero)

PINIT Pressure sensitivity flag:

.EQ. 0: Use current pressure

.EQ. 1: Use pressure from initial stress state

.EQ. 2: Use initial “plane stress”pressure

.EQ. 3: Use compressive initial vertical stress

TAUi Shear Stresses (if LCID is zero)

Field Comments






GAMY Reference Shear Strain

TAUY Reference Shear Stress

ALPHA Stress coefficient

R Stress exponent

BULK Elastic Bulk Modulus

Field Comments


Materials134


MAT_PLASTICITY_WITH_DAMAGE

An elasto-visco-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. Damage, in this model, is considered before rupture occurs.

Field Comments






E Young’s Modulus


SIGY Yield Stress


EPPF Plastic Strain, at which material softening begins

TDEL Minimum time step size for Automatic Element Deletion

C, P Strain Rate Parameters

LCSS Load Curve Id defining Effective Stress vs. Effective Plastic Strain

LCSR Load Curve Id defining Strain Rate Scaling Effect on Yield Stress

EPPFR Plastic Strain at which material ruptures







MAT_PLASTICITY_WITH DAMAGE_ORTHO_RCDC

An elasto-visco-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. This includes an orthotropic damage model (only for shell elements).

LCDM Load Curve Id defining nonlinear damage curve

NUMINT No. of through thickness integration points which must fail before the element is deleted

Field Comments






E Young’s Modulus


SIGY Yield Stress


EPPF Plastic Strain, at which material softening begins

TDEL Minimum time step size for Automatic Element Deletion

Field Comments


Materials136


C, P Strain Rate Parameter

LCSS Load Curve Id defining Effective Stress vs. Effective Plastic Strain


EPPFR Plastic Strain at which material ruptures




NUMINT No. of through thickness integration points which must fail before the element is deleted


ALPHA Parameter αBETA Parameter βGAMMA Parameter γD0 Parameter D0

B Parameter b

LAMDA Parameter λDS Parameter Ds

L Optional characteristic element length for this material.

Field Comments



MAT_FU_CHANG_FOAM

A material such as low and medium density foams, for hysteric unloading behaviors. Rate effects can be included in this material model.

Field Comments






E Young’s Modulus

ED Young’s Relaxation Modulus for rate effect


FAIL Failure option after Cutoff Stress is reached

0: Tensile Stress Remains at cutoff

1: Tensile Stress Resets to Zero

DAMP Viscous Coefficient

TBID Table Id for nominal Stress vs. Strain

Materials138

BVFLAG Bulk Viscosity activation Flag

0: No

1: Active

SFLAG Strain Rate Flag

0: True strain

1: Engineering strain

RFLAG Strain Rate evaluation flag

0 : First principal direction

1 : Principal strain rates for each principal direction

2: Volumetric strain rate

TFLAG Tensile Stress Evaluation Flag

0: Linear

1: Input via Load Curves with the tensile response corresponding to negative values of stress and strain

PVID Load Curve Id defining Pressure vs. Volumetric Strain

SRAF Strain Rate averaging flag

0: Weighted running average

1: Average of the last twelve values

REF User reference geometry to initialize the stress tensor.:

.EQ. 0: OFF

.EQ. 1: ON

HU Hysteric unloading factor between 0 and 1 (default = 1, i.e. no energy dissipation).

D0, N0, C0, Ni, Ci Material Constants

AIJ, SIJ Material Constants

MINR Minimum strain rate of interest

MAXR Maximum strain rate of interest

SHAPE Shape factor for unloading. Active for nonzero values of the hysteric unloading factor HU.

Field Comments



MAT_WINFRITH_CONCRETE

A smeared crack, smeared rebar, material model (only for the 8-noded single integration point continuum element).

Field Comments






TM Tangent Modulus of Concrete


UCS Uniaxial Compression Strength

UTS Uniaxial Tensile Strength

FE Depends on value for RATE

If RATE = 0, FE is Fracture Energy per unit area in opening crack

If RATE = 1, FE is crack width at which crack-normal tensile stress becomes zero

ASIZE Aggregate size (radius)

E Young’s Modulus for rebar

YS Yield Stress for rebar


Materials140


EH Hardening Modulus for rebar

UELONG Ultimate elongation before rebar fails

RATE Rate effects Flag

0: Included (MAT_0 84)

1: Turned off (MAT_0 85)

CONM Factor to convert model mass units to kg

CONL Factor to convert model length units to meters (if CONM .GT. 0)

CONT Factor to convert model time units to seconds

LCID Defining Pressure vs. Volumetric Strain

Field Comments



MAT_WINFRITH_CONCRETE_REINFORCEMENT

A rebar reinforcement material model (material type 84). Reinforcement quantity is defined as the ratio of the cross-sectional area of steel, relative to the cross-sectioanl area of concrete in the element (or layer).

Field Comments






TM Tangent Modulus of Concrete


UCS Uniaxial Compression Strength

UTS Uniaxial Tensile Strength

FE Depends on value for RATE

If RATE = 0, FE is Fracture Energy per unit area in opening crack

If RATE = 1, FE is crack width at which crack-normal tensile stress becomes zero

Materials142

ASIZE Aggregate size (radius)

E Young’s Modulus for rebar

YS Yield Stress for rebar

EH Hardening Modulus for rebar

UELONG Ultimate elongation before rebar fails

RATE Rate effects Flag

0: Included (MAT_0 84)

1: Turned off (MAT_0 85)

CONM Factor to convert model mass units to kg

CONL Factor to convert model length units to meters (if CONM .GT. 0)

CONT Factor to convert model time units to seconds

LCID Defining Pressure vs. Volumetric Strain

EID1 First element Id in group

EID2 Last element Id in group

INC Element increment for genaration

XR X-reinforcement quantity (for bars running parallel to global x-axis)

YR Y-reinforcement quantity (for bars running parallel to global y-axis)

ZR Z-reinforcement quantity (for bars running parallel to global z-axis)

PID Part Id of reinforced elements

AXIS Axis normal to layer:

.EQ. 1: A and B are parallel to global Y and Z, respectively

.EQ. 2 A and B are parallel to global X and Z, respectively

.EQ. 3: A and B are parallel to global X and Y, respectively

COOR Coordinate location of layer (X-coordinate if AXIS = 1, Y-Coordinate if AXIS = 2, Z-Coordinate if AXIS = 3)

RQA Reinforcement quantity (A)

RQB Reinforcement quantity (B)

Field Comments



MAT_ORTHOTROPIC_VISCOELASTIC

A viscoelastic material model (only for shell elements).

Field Comments






EA Young’s Modulus in Longitudinal Direction

EB Young’s Modulus in Transverse Direction

EC Young’s Modulus in Normal Direction

VF Volume fraction for viscoelastic material

K Elastic Bulk Modulus

G0 Short time Shear Modulus

GINF Long time Shear Modulus

BETA Decay Constant


Materials144









MANGLE Material Angle (Degrees), for AOPT=3





Field Comments



MAT_CELLULAR_RUBBER

A material model for a cellular rubber with confined air pressure, combined with linear viscoelasticity.

Field Comments







N Order or fit


SW Specimen Width


LCID Load Curve Id defining the Force vs. Actual Change in gauge Length

C10, C01, C11, C20, C02

Material Constants

P0 Initial Air Pressure

PHI Ratio of cellular rubber to rubber density

IVS Initial Volumetric Strain

G Optional shear relaxation modulus, G, for rate effects

BETA Optional Decay Constant

Materials146


MAT_MTS

This MTS material model, developed by Maudlin, Davidson, and Henninger [1990], is used for applications involving high pressures, large strains, and high strain rates. This model uses dislocation mechanics and provides an understanding of the plastic deformation process in ductile materials.

Field Comments






SIGA Dislocation interaction with long-range barriers

SIGI Dislocation interaction with interstitial atoms

SIGS Dislocation interaction with solute atoms

SIG0 NOT used

BULK Bulk Modulus (for shell elements)

HF0, HF1, HF2 Dislocation generation material constants

SIGSO Saturation Threshold stress at 0 degrees K




MAT_PLASTICITY_POLYMER

An elasto-plastic material model with arbitrary stress versus strain curve, and arbitrary strain rate dependency.

EDOTSO, EDOTO, EDOTI, EDOTS

Reference Strain rates

BURG Magnitude of Burgers vector

CAPA Material Constant, A

BOLTZ Boltzmann’s constant, k

SM0, SM1, SM2 Shear Modulus Constants

G0, GOI, GOS Normalized activation energies

PINV, QINV, PINVI, QINVI, PINVS., QINVS., ALPHA

Material Constants

RHOCPR Product of density and specific heat

TEMPRF Initial Element Temperature

EPSO Factor to normalize strain rate

Field Comments




Field Comments


Materials148


MAT_ACOUSTIC

Defines the properties of materials used to track low pressure waves in acoustic media, like air or water (only for acoustic pressure elements).





LCSS Load Curve Id defining Effective Stress vs. Total Effective Strain

LCSR Load Curve Id defining Strain Rate Scaling effect on Yield Stress

EFTX Failure Flag

0: Failure determined by Maximum tensile strain

1: Failure determined only by tensile strain in local x direction

2: Failure determined only by tensile strain in local y direction

DAMP Stiffness proportional damping ratio

RATEFAC Filtering factor for strain rate effect

LCFAIL Load Curve Id defining variation of Failure strain with Strain rate

Field Comments




Field Comments






C Sound Speed

BETA Damping Factor

CF Cavitation Flag

0: Off

1: On

ATMOS Atmospheric Pressure

GRAV Gravitational Acceleration constant

XP, YP, ZP Coordinates of free surface point

XN, YN, ZN Direction cosines of free surface normal vector

Field Comments


Materials150

MAT_SOFT_TISSUE

Defines a transversely isotropic hyperelastic material that represents biological soft tissue such as ligaments, tendons, and fascia.

Field Comments






Ci Hyperelastic Coefficients

XK Bulk Modulus

XLAM Stretch ratio at which fibers are straightened

FANG Fiber angle in local shell coordinate system (shell elements only)

XLAMO Initial fiber stretch

FAILSF stretch ratio for ligament fibers at failure (shell elements only). If zero, failure is not considered.

FAILSM stretch ratio for surrounding matrix material at failure (shell elements only). If zero, failure is not considered.



FAILSHR Shear strain at failure of a material point (shell elements only). If zero, failure is not considered. This failure value is independent of FAILSF and FAILSM.




AX, AY, AZ Components of first material axis point/vector

BX, BY, BZ Components of second material axis point/vector

LAX, LAY, LAZ Component of fiber orientation vector (Brick elements only)




Field Comments


Materials152

MAT_SOFT_TISSUE_VISCO

A transversely isotropic hyperelastic material model that represents biological soft tissue such as ligaments, tendons, and fascia. This model has a viscoelastic option activating a six-term Prony series kernel for the relaxation function.

Field Comments






Ci Hyperelastic Coefficients

XK Bulk Modulus

XLAM Stretch ratio at which fibers are straightened

FANG Fiber angle in local shell coordinate system (shell elements only)

XLAMO Initial fiber stretch



MAT_ELASTIC_6DOF_SPRING_DISCRETE_BEAM

A material model for simulating the effects of nonlinear elastic and nonlinear viscous beams using six springs each acting along one of it six degrees-of-freedom.




AX, AY, AZ Components of first material axis point/vector

BX, BY, BZ Components of second material axis point/vector

LAX, LAY, LAZ Component of fiber orientation vector (Brick elements only)

Si Spectral strengths for prony series relaxation kernel

Ti Characteristic time for prony series relaxation kernel

Field Comments






TPIDR Part Id governing the Translational motion in the local r direction (If zero, no force is computed in this direction)

Field Comments


Materials154


MAT_INELASTIC_SPRING_DISCRETE_BEAM

A material model for elastoplastic springs, with damping to be represented with discrete beam elements. A yield force versus deflection is used which can vary in tension and compression.

TPIDS Part Id governing the Translational motion in the local s direction (If zero, no force is computed in this direction)

TPIDT Part Id governing the Translational motion in the local t direction (If zero, no force is computed in this direction)

RPIDR Part Id governing the Rotational motion about the local r direction (If zero, no moment is computed in this direction)

RPIDS Part Id governing the Rotational motion about the local s direction (If zero, no moment is computed in this direction)

RPIDT Part Id governing the Rotational motion about the local t direction (If zero, no moment is computed in this direction)

Field Comments






K Elastic Loading/Unloading Stiffness

F0 Optional initial force

D Optional viscous damping coefficient

Field Comments




MAT_INELASTIC_6DOF_SPRING_DISCRETE_BEAM

A material model for nonlinear inelastic and nonlinear viscous beams using six springs each acting along one of it six degrees-of-freedom.

CDF Compressive displacement at failure

TDF Tensile Displacement at failure

FLCID Load Curve Id defining Yield Force vs. Plastic Displacement

HLCID Load Curve Id defining Force vs. Relative Velocity

C1, C2 Damping Coefficients

DLE Scale Factor for time unit

GLCID Load Curve Id defining a Scale Factor vs. Deflection for Load Curve Id, HLCID

Field Comments






TPIDR Part Id governing the Translational motion in the local r direction (If zero, no force is computed in this direction)

TPIDS Part Id governing the Translational motion in the local s direction (If zero, no force is computed in this direction)

TPIDT Part Id governing the Translational motion in the local t direction (If zero, no force is computed in this direction)

Field Comments


Materials156


MAT_BRITTLE_DAMAGE

A material model with anisotropic brittle damage characteristics, used mainly for concrete but can be applied for a variety of brittle materials.

RPIDR Part Id governing the Rotational motion about the local r direction (If zero, no moment is computed in this direction)

RPIDS Part Id governing the Rotational motion about the local s direction (If zero, no moment is computed in this direction)

RPIDT Part Id governing the Rotational motion about the local t direction (If zero, no moment is computed in this direction)

Field Comments






E Young’s Modulus


TLIMIT Tensile Limit

SLIMIT Shear Limit

FTOUGH Fracture Toughness

SRETEN Shear Retention

VISC Viscosity

Field Comments




MAT_GENERAL_JOINT_DISCRETE_BEAM

Defines the properties of a general joint constraining any combination of degrees of freedom between two nodes.

FRA_RF Fraction of reinforcement in section

E_RF Young’s Modulus of Reinforcement

YS_RF Yield Stress of Reinforcement

EH_RF Hardening Modulus of Reinforcement

FS_RF Failure Strain of Reinforcement

SIGY Compressive Yield Stress

Field Comments






TR Translational Constraint Code along r-axis

0: Free

1:Fixed

Field Comments


Materials158


TS Translational Constraint Code along s-axis

0: Free

1:Fixed

TT Translational Constraint Code along t-axis

0: Free

1:Fixed

RR Rotational Constraint Code about r-axis

0: Free

1:Fixed

RS Rotational Constraint Code about s-axis

0: Free

1:Fixed

RT Rotational Constraint Code about t-axis

0: Free

1:Fixed

RPST Penalty stiffness scale factor for translational constraints

RPSR Penalty stiffness scale factor for rotational constraints

Field Comments



MAT_SIMPLIFIED_JOHNSON_COOK

A material model used for problems where the strain rates vary over a large range. In this model, thermal effect and damage are ignored and maximum stress is directly limited since thermal softening is not available.


Field Comments






E Young’s Modulus





A, B, N, C Parameters used in the Johnson-Cook flow stress equation

PSFAIL Effective Plastic Strain at Failure

SIGMAX Maximum Stress obtained from Work Hardening before rate effects are added

SIGSAT Saturation Stress

EPSO Effective Plastic Strain rate


Materials160

MAT_SIMPLIFIED_JOHNSON_COOK_ORTHO_DAMAGE

Defines the properties of a material used for problems where the strain rates vary over a large range. Orthotropic damage is included as a means for treating failure in aluminum panels (only for shell elements with multiple through thickness integration points).

Field Comments






E Young’s Modulus





EPPFR Plastic Strain at which the material ruptures


NUMINT No. of through thickness integration points which must fail before element is deleted

A, B, N, C Parameters used in the Johnson-Cook flow stress equation

PSFAIL Effective Plastic Strain at Failure

SIGMAX Maximum Stress obtained from Work Hardening before rate effects are added

SIGSAT Saturation Stress

EPSO Effective Plastic Strain rate



MAT_SPOTWELD

A material model for spotweld modeled with beam element type 9, and solid element type 1.

Field Comments






E Young’s Modulus



ET Hardening Modulus

DT Time Step Size for Mass Scaling

TFAIL Failure Time (Ignored if value is zero)

EFAIL Effective Plastic Strain at Failure

NRR Axial force resultant NrrF (or Maximum Axial Stress σrrF) at failure

NRS Force resultant NrsF (or Maximum Shear Stress τF) at failure

NRT Force resultant NrtF at failure

MRR Torsional moment resultant MrrF at failure

MSS Moment resultant MssF at failure

MTT Moment resultant MttF at failure

NF No. of force vectors stored for filtering


Materials162


MAT_SPOTWELD_DAMAGE-FAILURE

A material model used in spotweld, modeled with beam element type 9, and solid element type 1. Damage parameters are also included in this model.

Field Comments






E Young’s Modulus



ET Hardening Modulus




NRR Axial force resultant NrrF (or Maximum Axial Stress σrrF) at failure

NRS Force resultant NrsF (or Maximum Shear Stress τF) at failure

NRT Force resultant NrtF at failure

MRR Torsional moment resultant MrrF at failure




MAT_SPOTWELD_DAIMLERCHRYSLER

A material model used in spotweld, modeled with solid element type 1, with type 6 hour glass control. Special Damage parameters are used in this model.

MSS Moment resultant MssF at failure

MTT Moment resultant MttF at failure

NF No. of force vectors stored for filtering

RS Rupture Strain

OPT Failure Option

0: Resultant based failure

1: Stress based failure computed from resultant (Toyota)

2: User subroutine to determine failure

3: Notch stress based failure (beam weld only)

4: Stress intensity factor at failure (beam weld only)

5: Structural stress at failure (beam weld only)

FVAL Failure parameter:

.EQ. 3: Notch stress value at failure (σKF)

.EQ. 4: Stress intensity factor value at failure (KeqF)

.EQ. 5: Structural stress value at failure (σSF)

.EQ. 6: Number of cycles that that failure condition must be met to trigger beam deletion.

.EQ. 9: Number of cycles that that failure condition must be met to trigger beam deletion.

Note: Values of -2, -1, 0, 1, 2, 7 - Not used

TRUE_T True weld thickness. This optional value is available for solid element failure by OPT = 0, 1, 7, or -2.

BETA Damage model decay rate.

Field Comments


Materials164


Field Comments






E Young’s Modulus





NF Number of failure function evaluations stored for filtering by time averaging.

RS Rupture Strain

TRUE_T True weld thickness for hexahedron solid weld element.

CON_ID Connection Id of *DEFINE_CONNECTION



MAT_GEPLASTIC_SRATE_2000a

Defines properties for the General Electric’s commercially available thermoplastics subjected to high strain rates. This model features variation of yield stress dependent upon strain rate, cavitation effects of rubber modified material, and automatic element deletion for either ductile or brittle materials.


Field Comments






E Young’s Modulus


RATESF Constant in plastic strain rate equation

EDOTO Reference Strain Rate

ALPHA Pressure Sensitive Factor

LCSS Load Curve Id (or Table Id) for post Yield Stress behavior vs. Strain

LCFEPS Load Curve Id for Plastic failure Strain vs. Strain Rate

LCFSIG Load Curve Id for Maximum principal failure Stress vs. Strain Rate

LCE Load Curve Id for Unloading Moduli vs. Plastic Strain


Materials166

MAT_HYPERBOLIC_SIN

Defines properties for modeling materials with temperature and rate dependent plasticity.


Field Comments






E Young’s Modulus







ALPHA, N, A, Q, G Material constitutive constants

EPSO Effective plastic strain rate



MAT_ANISOTROPIC_VISCOPLASTIC

Defines an anisotropic viscoplastic material that is applied to either shell or brick elements. The material constants may be input directly, or by stress-strain data. If stress-strain data is provided, a least squares fit will be performed to determine the constants.

Field Comments






E Young’s Modulus



FLAG Flag for material parameters

LCSS Load Curve Id for Effective Stress vs. Effective Plastic Strain

Materials168

ALPHA α distribution hardening:

=0: Kinematic hardening

= 1: Isotropic hardening

QRi, CRi Isotropic Hardening Parameters

QXi, CXi Kinematic Hardening Parameters

VK, VM Viscous Material Parameters

R00/F R00 for shell, or F for solid

R45/G R45 for shell, or G for solid

R90/H R90 for shell, or H for solid

L, M, N Parameters (for solid elements only







FAIL Failure flag:

.LT. 0: user defined failure subroutine to determine failure.

.EQ. 0: failure is not considered

.GT. 0: Plastic strain to failure. When the plastic strain reaches this value, the element is deleted from calculation.

Field Comments



NUMINT Number of integration point which must fail before element is deleted.. If zero, all points must fail. This option applies to shell elements only.

MACF Material axes change flag:



XP, YP, ZPP Coordinates of point p, for AOPT=1





Field Comments


Materials170

MAT_ANISOTROPIC_PLASTIC

This anisotropic plastic material model is a simplified version of the MAT_ANISOTROPIC_VISCOPLASTIC model. This model applies to shell elements only.

Field Comments






E Young’s Modulus



LCSS Load Curve Id for effective Stress vs. effective plastic Strain



R00/F R00 for shell or F for solid

R45/G R45 for shell or G for solid

R90/H R90 for shell or H for solid



S11, S22, S33, S12 Yield Stress in the x, y, z and xy direction, respectively







XP, YP, ZP Coordinates of point p, for AOPT=1

Ai Components of Vector a, for AOPT=2

Vi Components of Vector v, for AOPT=3

Di Components of Vector d, for AOPT=2


Field Comments


Materials172

MAT_DAMAGE_1

Defines properties for a continuum damage mechanics material model which includes anisotropy and viscoplasticity. This model is applied to shell, thick shell and brick elements.

Field Comments






E Young’s Modulus




LCDM Load Curve Id defining nonlinear damage (for FLAG = -1)

Qi, Ci Isotropic Hardening Parameters

EPSD Damage Threshold, rd


S Damage Material Constant

EPSR Plastic strain at which material ruptures

DC Critical Damage valueDc

FLAG Flag for Localization

-1: Anisotropic damage

0: No calculation of localization due to damage

1: Flag those elements where local stabilization occurs

VK, VM Viscous Material Parameter

R00/F R00 for shell or F for solid

R45/G R45 for shell or G for solid

R90/H R90 for shell or H for solid

L, M, N Parameters (for solid elements only







XP, YP, ZP Coordinates of point p, for AOPT=1



Field Comments

Materials174


MAT_DAMAGE_2

Defines properties for an elastic viscoplastic material model combined with the continuum damage mechanics. This model is applied to shell, thick shell and brick elements.



Field Comments






E Young’s Modulus


SIGY Yield Stress


FAIL Failure flag

=0: Failure due to plastic strain not considered

> 0: Plastic strain to failure considered. When the plastic strain reaches this value, the element is deleted from calculation.

Field Comments




MAT_ELASTIC_VISCOPLASTIC_THERMAL

Defines properties for an elastic viscoplastic material with thermal effects.

TDEL Minimum time step for Automatic Element Deletion


LCSS Load Curve Id defining effective Stress vs. effective plastic Strain


EPSD Damage Threshold, rd

S Damage Material Constant

DC Critical Damage valueDc

Field Comments






E Young’s Modulus


Field Comments


Materials176



ALPHA Coefficient of thermal expansion




C, P Viscous Material Parameters

LCE Load Curve Id defining Young’s Modulus vs. Temperature

LCPR Load Curve Id defining Poisson’s Ratio vs. Temperature

LCSIGY Load Curve Id defining Initial Yield Stress vs. Temperature

LCR Load Curve Id defining for Parameters QR1 and QR2 vs. Temperature

LCX Load Curve Id defining for Parameters QX1 and QX2 vs. Temperature

LCALPH Load Curve Id defining Coefficient of thermal expansion vs. Temperature

LCC Load Curve Id defining scaling Viscous material parameter C vs. Temperature

LCP Load Curve Id defining scaling Viscous material parameter P vs. Temperature

Field Comments



MAT_JOHNSON_HOLMQUIST_CERAMICS

Defines properties for a material used to model ceramics, glass and other brittle materials.

Field Comments






G Shear Modulus

A Intact normalized strength parameter

B Fractured normalized strength parameter

C Strength Parameter (for strain rate dependence)

M Fracture strength parameter (Pressure exponent)

N Intact strength parameter (Pressure exponent)

EPSI Reference Strain Rate

T Maximum Tensile Strength

SFMAX Maximum normalized Fractured Strength

HEL Hugoniot elastic limit

PHEL Pressure component at the at Hugoniot elastic limit

BETA Fraction of elastic energy loss converted to hydrostatic energy

Di Parameters for plastic strain to fracture

K1, K2 First and Second pressure coefficients

Materials178


MAT_JOHNSON_HOLMQUIST_CONCRETE

This material model is used for concrete under high strain rates, large strains and high pressure.

K3 Elastic Constant (Note that K1 is the bulk modulus)

FS Failure Criteria

<0: Fails if (p* + t*) is negative (tensile failure)

0: No failure

>0: Fails if strain exceeds FS

Field Comments






G Shear Modulus

A Normalized Cohesive Strength

B Normalized Pressure Hardening

C Strain rate coefficient

N Pressure Hardening Exponent

Field Comments




MAT_FINITE_ELASTIC_STRAIN_PLASTICITY

An elasto-plastic material model with arbitrary stress-strain curve and arbitrary strain rate dependency. This material model uses a finite strain formulation allowing large elastic strains before yielding.

FC Quasi-static uniaxial compressive strength

T Maximum Tensile hydrostatic pressure

EPSO Reference Strain Rate

EFMIN Plastic strain before fracture

SFMAX Maximum Fractured Strength

PC Crushing Pressure

UC Crushing Volumetric Strain

PL Locking Pressure

UL Locking Volumetric Strain

D1, D2 Damage Constants

K1, K2, K3 Pressure Constants

FS Failure Type

Field Comments






Field Comments


Materials180


MAT_LAYERED_LINEAR_PLASTICITY

Defines a layered elastoplastic material with an arbitrary stress-strain curve and arbitrary strain rate dependency.

E Young’s Modulus


SIGY Yield Stress


FAIL Failure Flag

<0: User defined failure subroutine is called to determine failure

=0: Failure is not considered.

>0: Plastic strain to failure. When plastic strain reaches this value, the element is deleted from calculation.




LCSR Load Curve Id defining Strain Rate Effect on Yield Stress

Field Comments



Field Comments




MAT_UNIFIED_CREEP

Defines properties of a material for elastic creep behavior.




E Young’s Modulus


SIGY Yield Stress


FAIL Failure Flag

<0: User defined failure subroutine is called to determine failure

=0: Failure is not considered.

>0: Plastic strain to failure. When plastic strain reaches this value, the element is deleted from calculation.




LCSR Load Curve Id defining Strain Rate Effect on Yield Stress

Field Comments




Field Comments


Materials182


MAT_COMPOSITE_LAYUP

Defines the elastic response of composite layups that have an arbitrary number of layers through the shell thickness.



E Young’s Modulus


A Stress Coefficient

N Stress Exponent

M Time Exponent

Field Comments






EA Young’s Modulus, a Direction

Field Comments




EB Young’s Modulus, b Direction

EC Young’s Modulus, c Direction









XP, YP, ZP Coordinates of point p for AOPT=1 and 4


Vi Component of Vector v, for AOPT=3 and 4



Field Comments


Materials184

MAT_COMPOSITE_MATRIX

Defines the properties of materials used for the elastic response of composites where pre-integration is used to compute the extensional, bending, and coupling stiffness coefficients (available only for Belytschko-Tsay resultant shell formulation).

Field Comments






Cij Coefficient of Stiffness Matrix














Field Comments


Materials186

MAT_COMPOSITE_DIRECT

Defines properties for a material used for the elastic response of composites where pre-integration is used to compute the extensional, bending, and coupling stiffness coefficients (available only for Belytschko-Tsay resultant shell formulation).


Field Comments






Cij Coefficient of Stiffness Matrix



MAT_GENERAL_NONLINEAR_6DOF_DISCRETE_BEAM

Defines the properties of a very general spring and damper. The beam is based on MAT_SPRING_GENERAL_NONLINEAR option. This model includes additional unloading options.

Field Comments






KT Translational stiffness for unloading option 2.0

KR Rotational Stiffness for unloading option 2.0

UNLDOPT Unloading Option

OFFSET Offset Factor (between 0 and 1)

Materials188


DAMPF Damping factor for stability

LCIDTR, LCIDTS, LCIDTT

Load Curve Id defining Translational Force resultant along r, s, t axes respectively vs. Translational Displacement.

LCIDRR, LCIDRS, LCIDRT

Load Curve Id defining Rotational Moment about r, s, t axes vs. Rotational Displacement.

LCIDTUR, LCIDTUS, LCIDTUT

Load Curve Id defining Translational Force resultant along r, s, t axes vs. Translational Displacement during unloading

LCIDRUR, LCIDRUS, LCIDRUT

Load Curve Id defining Rotational Moment about r, s, t axes vs. Rotational Displacement during unloading.

LCIDTDR, LCIDTDS, LCIDTDT

Load Curve Id defining Translational Damping Force along r, s, t axes vs. relative Translational Velocity.

LCIDRDR, LCIDRDS, LCIDRDT

Load Curve Id defining Rotational Damping Moment about r, s, t axes vs. relative Rotational Velocity.

LCIDTER, LCIDTES, LCIDTET

Load Curve Id defining Translational Damping Force scale factor vs. relative Displacement along r, s, t axes

LCIDRER, LCIDRES, LCIDRER

Load Curve Id defining Rotational Damping Moment scale factor vs. relative Displacement along r, s, t axes

UTFAILR, UTFAILS, UTFAILT

Translational Displacement along r, s, t at failure in Tension

WTFAILR, WTFAILS, WTFAILT

Rotational Displacement about r, s, t at failure in Tension

UCFAILR, UCFAILS, UCFAILT

Translational Displacement along r, s, t at failure in Compression

WCFAILR, WCFAILS, WCFAILT

Rotational Displacement about r, s, t at failure in Compression

IUR, IUS< IUT Initial Translational Displacement along r, s, t directions

IWR, IWS, IWT Initial Rotational Displacement about r, s, t axes

Field Comments



MAT_GURSON

Defines the material properties for the Gurson dilational plastic material model (available only for shell elements).

Field Comments






E Young’s Modulus


SIGY Yield Stress

N Exponent in power law

Q1, Q2 Parameters

FC Critical void volume fraction

F0 Initial void volume fraction

EN Mean nucleation strain

SN Standard deviation SN of the normal distribution of εN

FN Void Volume Fraction of nucleating particles

ETAN Hardening Modulus

Materials190


ATYP Hardening Type

1: Power Law

2: Linear

3: 8 points curve

FF0 Failure void volume fraction

Li Element Length Value

FFi Corresponding failure void volume fraction

LCSS Load Curve id defining effective Stress vs. effective plastic Strain

LCLF Load Curve Id defining Failure Void Volume Fraction vs. Element Length

NUMINT No of through thickness integration points which must fail before element is deleted

LCF0 Lod curve Id defining initial void volume fraction f0 vs. element length.

LCFC Lod curve Id defining initial void volume fraction fN vs. element length.

LCFN Lod curve Id defining initial void volume fraction f0 vs. element length.

VGTYP Type of void growth behavior:

.EQ. 0: void growth in tension, and void contraction in compression, but never below f0 (default).

.EQ. 1: void growth in tension only.

.EQ. 2: void growth in tension, and void contraction in compression, even below f0.

Field Comments



MAT_GURSON_RCDC

Defines the material properties for the Gurson model with Wilkins Rc-Dc (for shell elements only).

Field Comments






E Young’s Modulus


SIGY Yield Stress

N Exponent in power law

Q1, Q2 Parameters

FC Critical void volume fraction

F0 Initial void volume fraction

EN Mean nucleation strain

SN Standard deviation SN of the normal distribution of εN

FN Void Volume Fraction of nucleating particles

Materials192


ETAN Hardening Modulus

ATYP Hardening Type

1: Power Law

2: Linear

3: 8 points curve

FF0 Failure void volume fraction

Li Element Length Value

FFi Corresponding failure void volume fraction

LCSS Load Curve id defining effective Stress vs. effective plastic Strain

LCLF Load Curve Id defining Failure Void Volume Fraction vs. Element Length

NUMINT No of through thickness integration points which must fail before element is deleted

ALPHA Parameter α for Rc-Dc Model

BETA Parameter β for Rc-Dc Model

GAMMA Parameter γ for Rc-Dc Model

D0 Parameter D0 for Rc-Dc Model

B Parameter b for Rc-Dc Model

LAMBDA Parameter λ for Rc-Dc Model

DS Parameter ds for Rc-Dc Model

L Characteristic element length for Rc-Dc Material

Field Comments



MAT_GENERAL_NONLINEAR_1DOF_DISCRETE_BEAM

Defines the material properties for a very general spring and damper. The beam is based on MAT_SPRING_GENERAL_NONLINEAR option and is a one dimensional version of 6DOF_DESCRETE_BEAM. This model includes additional unloading options.

Field Comments






K Translational stiffness for unloading option 2

UNLDOPT Unloading option

OFFSET Offset to determine permanent set upon unloading if the UNLDOPT equals to 3.

DAMPF Damping factor for stability

LCIDT Load Curve Id defining Translational Force along the axis vs. relative Translational Displacement.

LCIDTU Load Curve Id defining Translational Force along the axis vs. relative Translational Displacement, during unloading

LCIDTD Load Curve Id defining Translational Damping Force along the local axis vs. relative Translational Velocity.

LCIDTE Load Curve Id defining Translational Damping Force scale factor along the local axis vs. relative Displacement.

UTFAIL Translational displacement at failure in tension

Materials194


MAT_HILL_3R

Defines the properties for the Hill’s planar anisotropic material model with 3 R values.

UCFAIL Translational displacement at failure in compression

IU Initial translational displacement along the axis

Field Comments






E Young’s Modulus


Field Comments




HR Hardening Rule

1: Linear

2: Exponential

3: Load Curve

P1, P2 Material Parameters

R00, R45, R90 Lankford parameters

LCID Load Curve Id for the hardening rule

Epsilon_0 ε0 for determining initial yield stress for exponential hardening

SPI Parameter to redefine ε0











Field Comments


Materials196

MAT_MODIFIED_PIECEWISE_LINEAR_PLASTICITY

Defines an elasto-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency (available only for shell elements).


Field Comments






E Young’s Modulus


SIGY Yield Stress


FAIL Failure flag



LCSS Load Curve Id defining effective Stress vs. effective plastic Strain

LCSR Load Curve Id defining Strain Rate scaling effect on Yield Stress


EPSTHIN Thinning Plastic Strain at Failure

EPSMAJ Major Plastic Strain at Failure

NUMINT No. of through thickness integration points that must fail before element is deleted



MAT_PLASTICITY_COMPRESSION_TENSION

Defines an isotropic elastic-plastic material allowing different yield stress versus plastic strain curves in compression and tension.

Field Comments






E Young’s Modulus



FAIL Failure Flag


LCIDC Load Curve Id defining Yield Stress vs. effective Plastic Strain in compression

LCIDT Load Curve Id defining Yield Stress vs. effective Plastic Strain in tension

Materials198


LCSRC Optional load curve Id defining strain rate scaling effect on yield stress when the material is in compression

LCSRT Optional load curve Id defining strain rate scaling effect on yield stress when the material is in tension

SRFLAG Formulation for rate effects:

.EQ. 0: Total strain rate ; .EQ. 1: Deviatoric strain rate

LCFAIL Load curve Id defining failure strain vs. strain rate

PC Compressive mean stress (pressure) at which the yield stress follows the Load Curve ID, LCIDC

PT Tensile mean stress (pressure) at which the yield stress follows the Load Curve ID, LCIDT

PCUTC Pressure cut-off in compression

PCUTT Pressure cut-off in tension

PCUTF Pressure cut-off flag:

0 = inactive ; 1 = active

K (optional) bulk modulus for the viscoelastic material. If nonzero, a Kelvin type will be used.

NUM_RFS Number of terms used for shear relaxationmodulus/shear decay constant

GI1 (optional) shear relaxation modulus for the i-th term

BETAI1 (optional) shear decay constant for the i-th term

Field Comments



MAT_MODIFIED_HONEYCOMB

Defines the properties for aluminum honeycomb crushable foam materials with anisotropic behavior.

Field Comments






E Young’s Modulus


SIGY Yield Stress

VF Relative volume at which honeycomb is fully compacted

MU Material viscosity coefficient

BULK Bulk Viscosity Flag

0: Not used

1: Active and MU=0

Materials200

LCA Load Curve ID, defining:

>0: Stress along a- axis vs. strain along a-axis

<0: Yield stress vs. the angle off the material axis is degrees

LCB Load Curve ID, defining:

>0: Stress along b- axis vs. strain along b-axis

<0: the strong axis stress vs. volumetric strain

LCC Load Curve ID, defining:

>0: Stress along c- axis vs. strain along c-axis

<0: the wreak axis stress vs. volumetric strain

LCS Load Curve ID, defining:

>0: Shear Stress vs. shear strain

<0: the damage curve defining the shear stress multiplier as a function of the shear strain component

LCAB Load Curve ID, defining:

>0: Shear Stress-ab vs. shear strain-ab

<0: the damage curve defining the shear stress-ab multiplier as a function of the shear strain-ab

LCBC Load Curve ID, defining:

>0: Shear Stress-bc vs. shear strain-bc

<0: the damage curve defining the shear stress-bc multiplier as a function of the shear strain-bc

LCCA Load Curve ID, defining:

>0: Shear Stress-ca vs. shear strain-ca

<0: the damage curve defining the shear stress-ca multiplier as a function of the shear strain-ca

LCSR Load Curve ID of Strain Rate effect scale factor vs. Strain Rate

EAAU, EBBU, ECCU Elastic Moduli in the a-, b-, and c- directions, in uncompressed configuration

GABU, GBCU, GCAU Shear Moduli in the ab, bc, ca planes in uncompressed configuration

Field Comments








MSCF Material axes change flag:

1 = no change (default) ; 2 = switch material axes a and b

3 = switch material axes a and c ; 4 = switch material axes b and c






TSEF Tensile Strain at Element Failure

SSEF Shear Strain at Element Failure

VREF Relative volume at which the reference geometry is stored (for solid elements 1, 2, 3, 4, 10)

Field Comments

Materials202


MAT_ARRIBA_BOYCE_RUBBER

Defines the material properties for hyperelastic rubber combined optionally with linear viscoelasticity.

TREF Element timestep size at which the reference geometry is stored

SHDFLG Flag defining treatment of damage from curves LCS, LCAB, LCBC, and LCBC (relevant only if LCA < 0):

.EQ. 0: damage reduces shear stress every time step

.EQ. 1: damage = (shear stress)/(undamaged shear stress)

Field Comments






K Bulk Modulus

G Shear Modulus

N Number of statistical links

Field Comments




MAT_HEART_TISSUE

Defines the material properties for heart tissue as described in the paper by Guccione, McCulloch and Waldman [1991]. This model is transversely anisotropic.

LCID Load Curve id defining Relaxation curve for shear


NT Number of Prony series terms in fit


GIi Optional i-th shear Relaxation Modulus i

BETAIi Optional i-th shear Decay Constant

Field Comments






C, B1, B2, B3 Material Coefficients

Field Comments


Materials204


P Pressure in muscle tissue














BETA Material Angle (Degrees), for AOPT = 3

Field Comments



MAT_LUNG_TISSUE

Defines the material properties for a hyperelastic material model for heart tissue combined optionally with linear viscoelasticity.


Field Comments






K Bulk Modulus

C, DELTA, ALPHA, BETA, C1, C2

Material Coefficients

LCID Relaxation curve for shear


NT Number of Prony series terms in fit


GIi Optional i-th shear Relaxation Modulus

BETAIi Optional i-th shear Decay Constant


Materials206

MAT_SPECIAL_ORTHOTROPIC

This material model defines the properties for a material model developed for the Belytschko-Tsay and the C0 triangle shell elements. It is based on a resultant stress formulation. In plane behavior is treated separately from bending in order to model perforated materials such as television shadow masks.

Field Comments






YS Yield Stress

EP Plastic Hardening Modulus

EiiP Young’s Modulus (in-plane) in i- direction

NUijP Poisson’s Ratio in plane ij

GijP Shear Modulus in Plane ij

EiiB Young’s Modulus (Bending) in i-direction

NUijB Poisson’s Ratio (Bending) in ij plane

G12B Shear Modulus (Bending) in 12 plane








blank i Blank Field




BETA Material angle (degrees), for AOPT = 3

Field Comments


Materials208

MAT_MODIFIED_FORCE_LIMITED

This material model is an extension of MAT_FORCE_LIMITED (MAT_029). In addition to plastic hinge and collapse mechanisms, yield moments may be defined as a function of axial force. The moment transmitted by the hinge is defined by a moment-plastic rotation relationship.


Materials210

Field Comments






E Young’s Modulus



DF Damping Factor

AOPT Axial load curve option

0: Force vs. Strain

1: Force vs. change in length

YTFLAG Flag to allow beam to yield

ASOFT Axial elastic softening factor

M1, M2, ..., M8 Applied End Moments

LC1, LC2, ..., LC8 Load Curve Ids corresponding to applied end moments

LPSi Load Curve Id for plastic moment vs. rotation about s-axis at node i

SFSi Scale factor, plastic moment vs. rotation about s- axis at node i

YMSi Yield moment about s- axis at node i for interaction calculations

LPTi Load Curve Id for plastic moment vs. rotation about t-axis at node i

SFTi Scale factor, plastic moment vs. rotation about t- axis at node i

YMTi Yield moment about t- axis at node i for interaction calculations

LPR Load Curve Id for plastic torsional moment vs. rotation

SFR Load Curve Id for Scale factor vs. rotation

YMR Torsional Yield moment for interaction calculation

LYSi Load Curve Id for yield moment vs. axial force along axis s at node i

SYSi Load Curve Id for Scale factor applied to corresponding load curve LYSi

LYTi Load Curve Id for yield moment vs. axial force along axis t at node i

SYTi Load Curve Id for Scale factor applied to corresponding load curve LYTi

LYR Load Curve Id for yield moment vs. axial force for the torsional axis

LYS Load Curve Id for the Scale factor applying to LYR

HMS1_i Hinge moments for s axis at node 1 for hinge i

LPMS1_i Load Curve Id for plastic moment vs. plastic rotation for HMS1_i

HMS2_i Hinge moments for s axis at node 2 for hinge i

LPMS2_i Load Curve Id for plastic moment vs. rotation for HMS2_i

HMT1_i Hinge moments for t axis at node 1 for hinge i

LPMT1_i Load Curve Id for plastic moment vs. rotation for HMT1_i

HMT2_i Hinge moments for t axis at node 2 for hinge i

LPMT2_i Load Curve Id for plastic moment vs. rotation for HMT2_i

Field Comments

Materials212


MAT_VACUUM

Defines the properties for a dummy material representing a vacuum in a multi-material Euler/ALE model.


HMR_i Hinge moment for the torsional axis for hinge i

LPMR_i Load Curve Id for plastic moment vs. plastic rotation for HMR_i

Field Comments





KW_OPTION Title optional keywords

Field Comments




MAT_RATE_SENSITIVE_POLYMER

Defines the properties for simulating an isotropic ductile polymer with strain rate effects. It uses uniaxial test data.


Field Comments






E Young’s Modulus


D0 Reference Strain Rate (D0)

N Exponent for inelastic strain rate

Z0 Initial hardness of material (Z0)

q Parameter used in the constitutive equation

Omega Maximum internal stress


Materials214

MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM

Defines the properties for extruded foam material that is transversely anisotropic, crushable, and of low density with no significant Poisson effect.

Field Comments






E11, E22 Elastic Moduli in the 1(axial) and 2 (transverse) direction

E12 Elastic shear Modulus in the axial-transverse plane (E12 = E13)

G Shear Modulus

K Bulk Modulus for Contact Stiffness

I11 Load Curve Id for Nominal Axial Stress vs. Volumetric Strain

I22 Load Curve Id for Nominal Transverse Stress vs. Volumetric Strain (I22= I33)

I12 Load Curve Id for Shear Stress components 12 and 31 vs. Volumetric Strain (I22= I31)

I23 Load Curve Id for Shear Stress components 23 vs. Volumetric Strain



IAA Load Curve Id for Nominal stress vs. Volumetric strain at angle, ANG, relative to the material axis

NY Flag for symmetric yield surface

ANG Angle corresponding to Load Curve Id, IAA

MU Damping factor





ISCL Load Curve Id for the strain rate scale factor vs. volumetric strain rate. The yield rate is scaled by the value specified by the load curve.

MSCF Material axes change flag:







Vi Components of vector v (for AOPT = 3 or 4)


Field Comments


Materials216

MAT_WOOD

Defines the material properties for a transversely isotropic material (available only for solid elements).

Field Comments







NPLOT Plotting Option

1: Parallel damage

2: Perpendicular damage

ITER Number of plasticity algorithm iterations

IRATE Rate effects option

0: Turn off

1: Turn on

HARD Perfect plasticity override

IFAIL Erosion perpendicular to the ground

0: No

1: Yes

IVOL Erode on negative volume or strain increments greater than 0.01

=0 No (default) ; =1 Yes

EL Parallel Normal Modulus

ET Perpendicular Normal Modulus

GLT Parallel Shear Modulus (GLT=GLR)

GTR Perpendicular Shear Modulus


XT Parallel Tensile Strength

XC Parallel Compressive Strength

YT Perpendicular Tensile Strength

YC Perpendicular Compressive Strength

SXY Parallel Shear Strength

SYZ Perpendicular Shear Strength

GF1_I Parallel Fracture Energy in Tension

GF2_I Parallel Fracture Energy in Shear

BFIT Parallel softening Parameter

DMAX_I Parallel Maximum Damage

GF1_r Perpendicular Fracture Energy in Tension

GF2_r Perpendicular Fracture Energy in Shear

Field Comments

Materials218

DFIT Perpendicular Softening Parameter

DMAX_r Perpendicular Maximum Damage

FLPAR Parallel Fluidity Parameter for Tension and Shear

FLPARC Parallel Fluidity Parameter for Compression

POWPAR Parallel Power

FLPER Perpendicular Fluidity Parameter for Tension and Shear

FLPERC Perpendicular Fluidity Parameter for Compression

POWPER Perpendicular Power

NPAR Parallel Hardening initiation

CPAR Parallel Hardening Rate

NPER Perpendicular Hardening initiation

CPER Perpendicular Hardening Rate








BETA Material angle in degrees (for AOP = 3)






Vi Components of vector v( for AOP = 3 and 4)

Field Comments



MAT_WOOD_PINE

Defines the material properties for a transversely isotropic material (available only for solid elements). This model has default material properties for yellow pine.

Field Comments







1: Parallel damage




Materials220


0: Turn off

1: Turn on



0: No

1: Yes



MOIS Percentage moisture content

TEMP Temperature

QUAL_T Quality Factor Option in Tension

QUAL_C Quality Factor Option in Compression

UNITS Units Option

0: GPa, mm, msec, Kg/mm3, KN

1: MPa, mm, msec, g/mm3, N

2: MPa, mm, sec, Mg/mm3, N

3:Psi, inch, sec, lb-sec2/inch4, lb.

IQUAL Apply quality factors perpendicular to grain

0: Yes

1: No

Field Comments

















Field Comments


Materials222

MAT_WOOD_FIR

Defines the material properties for a transversely isotropic material (available only for solid elements). This model has default material properties for Douglas Fir.

Field Comments







1: Parallel damage




0: Turn off

1: Turn on




0: No

1: Yes



MOIS Percentage moisture content

TEMP Temperature

QUAL_T Quality Factor Option in Tension

QUAL_C Quality Factor Option in Compression

UNITS Units Option

0: GPa, mm, msec, Kg/mm3, KN

1: MPa, mm, msec, g/mm3, N

2: MPa, mm, sec, Mg/mm3, N

3:Psi, inch, sec, lb-sec2/inch4, lb.

IQUAL Apply quality factors perpendicular to grain

0: Yes

1: No








Field Comments

Materials224


MAT_PITZER_CRUSHABLE_FOAM

Defines the properties for a material model that simulates isotropic crushable foams with strain rate effects. It uses uniaxial and triaxial data.








Field Comments






K Bulk Modulus

G Shear Modulus


TY Tension Yield

SRTV Young’s Modulus

LCPY Load Curve Id defining pressure vs. volumetric strain

Field Comments




LCUYS Load Curve Id defining uniaxial stress vs. volumetric strain

LCRS Load Curve Id defining Strain rate Scale Factor vs. Volumetric Strain rate

VC Viscous Damping Coefficient

DFLG Density Flag

0:Use Initial Density value

1: Use Current Density value

Field Comments


Materials226

MAT_SCHWER_MURRAY_CAP_MODEL

Defines the material properties for a three invariant extension of MAT_GEOLOGIC_CAP_MODEL (MAT_025) that also includes viscoplasticity for rate effects and damage mechanics to model strain softening.

Field Comments






SHEAR Shear Modulus

BULK Bulk Modulus

GRUN Gruneisen Ratio

SHOCK Shock Velocity Parameter

PORE Flag for Pore Collapse

0: Yes

1: Constant Bulk Modulus



ALPHA, THETA, GAMMA, BETA

Shear Failure Parameters

EFIT, FFIT Dilitation damage mechanics parameters

ALPHAN, CALPHA Kinematic strain hardening parameters

R0 Initial Gap Surface ellipticity, R

X0 Initial Gap Surface J1 (mean stress) axis intercept

IROCK Material Flag

0: Soils (cap can contact)

1: Rock/Concrete

SECP Shear Enhanced Compaction

AFIT, BFIT, RDAM0 Ductile damage mechanics parameters

W, D1, D2 Plastic volume strain parameters

NPLOT History variable post-processed as effective plastic strain

EPSMAX Maximum permitted strain increment

CFIT, DFIT Brittle damage parameters

TFAIL Tensile Failure Stress

FAILFL Failure Flag (failed element)

DBETA, DDELTA Rounded Vertices Parameters

VPTAU Viscoplastic Relaxation time Parameter

ALPHA1 THETA1, GAMMA1, BETA1

Torsional scaling parameters

ALPHA2 THETA2, GAMMA2, BETA2

Triaxial extension scaling parameters

Field Comments


Materials228

MAT_1DOF_GENERALIZED_SPRING

Defines the properties for a linear spring or damper that allows different degrees-of-freedom at two nodes to be coupled with linear spring and/or damper.


Field Comments






K Spring Stiffness

C Damping Constant

SCLNi Scale Factor on force at node i

DOFNi Active dof at node i

CIDi Local coordinate system Id at node 1 and node 2 respectively



MAT_FHWA_SOIL

Defines the material properties for an isotropic material with damage for solid elements. The model has a modified Mohr-Coulomb surface for determining pressure dependent peak shear strength.

Field Comments






NPLOT Plotting option

SPGRAV Specific gravity of soil

RHOWAT Density of water

VN, GAMMAR Viscoplastic parameters

ITERMAX Maximum number of plastic iterations

K Bulk Modulus

G Shear Modulus

PHIMAX Peak Shear strength (friction) angle (degrees)

AHYP Coefficient A for modified Drucker-Prager surface

COH Cohesion shear strength at zero confinement (overburden)

ECCEN Eccentricity parameter

AN Strain hardening percent of PHIMAX where nonlinear effects start

ET Strain hardening amount of nonlinear effects

Materials230


MAT_FHWA_SOIL_NEBRASKA

Defines the material properties for a soil model with default property values for soils used at the University of Nebraska. Default units are in millimeter, milliseconds and kilograms.


MCONT Moisture content in soil

PWD1 Parameter for pore water effects on Bulk Modulus

PWSK Skeleton Bulk Modulus

PWD2 Parameter for pore water effects on the effective pressure

PHIRES Minimum internal frictional angle (radians)

DINT Volumetric strain at initial threshold damage

VDFM Void formation energy

DAMLEV Level of damage that will cause element deletion

EPSMAX Maximum principal failure strain

Field Comments





FCTIM Factor to multiply milliseconds by to get desired time unit

FCTMAS Factor to multiply Kg by to get desired mass unit

FCTLEN Factor to multiply mm by to get desired length unit

Field Comments




MAT_GAS_MIXTURE

Defines the material properties for a material model that simulates gas mixture and works in conjunction with the multi-material ALE formulation.

Field Comments





IADIAB Flag for turning adiabatic compression logic ON/OFF

0 = ON ; 1 = OFF

RUNIV Universal gas constant in per-mole unit

CVi Heat Capacity at constant volume for upto eight different gases in per-mass unit gas (If RUNIV = 0 or blank)

MOLi Molecular weight of each ideal gas in the mixture (mass-unit/molde) (if RUNIV is nonzero)

CPi Heat Capacity at constant pressure for upto eight different gases in per-mass unit gas (If RUNIV = 0 or blank)

Materials232


MAT_CFD

Defines the material properties for a material model that allows constant, isotropic fluid properties to be defined for the incompressible/low-Mach CFD solver.

Bi First order coefficient for a temperature dependent heat capacity at constant pressure for up to eight different gases (If RUNIV = 0 or blank)

Ci Second order coefficient for a temperature dependent heat capacity at constant pressure for up to eight different gases (If RUNIV = 0 or blank)

Field Comments





RHO Fluid Density

MU Fluid Viscosity

K Thermal Conductivity

CP Heat Capacity

BETA Coefficient of expansion

TREF Reference Temperature

Field Comments




MAT_CFD_CONSTANT

Defines the material properties for a material model that allows constant, isotropic fluid properties to be defined for the incompressible/low-Mach CFD solver.

GX, GY, GZ Gravitational acceleration in the X, Y, Z direction

DIFFi Diffusivity for Species i

Field Comments





RHO Fluid Density

MU Fluid Viscosity

K Thermal Conductivity

CP Heat Capacity

BETA Coefficient of expansion

TREF Reference Temperature

GX, GY, GZ Gravitational acceleration in the X, Y, Z direction

DIFFi Diffusivity for Species i

Field Comments


Materials234


MAT_DESHPANDE_FLECK_FOAM

Defines the material properties for aluminum foam, used as a filler material in aluminum extrusions to enhance the energy absorbing capability of the extrusion.


Field Comments






E Young’s Modulus


ALPHA Parameter to Control Shape of yield surface

GAMMA, ALPHA2, BETA, SIGP

Equation parameters

EPSD Densification strain

DERFI Type of derivation in Material subroutine

0: Numerical

1: Analytical

CFAIL Failure Strain




MAT_COMPOSITE_MSC

Defines the material properties for a material model to simulate the progressive failure analysis for composite materials consisting of unidirectional and woven fabric layers.

Field Comments






EA Young’s Modulus - longitudinal direction

EB Young’s Modulus - transverse direction

EC Young’s Modulus - through thickness direction


GAB, GBC, GCA Shear Stress in ab bc, and ca directions

Materials236





MACF Material Axes change flag:

= 1 no change (default)

= 2, switch material axes a and b

= 3, switch material axes a and c

= 4, switch material axes b and c







BETA Layer in-plane rotational Angle (degrees)

SAT Longitudinal Tensile Strength

SAC Longitudinal Compressive Strength

SBT Transverse Tensile Strength

SBC Transverse Compressive Strength

SCT Through thickness Tensile Strength

SFC Crush Strength

SFS Fiber mode shear strength

SAB, SBC, SCA Matrix mode Shear Strength in ab bc, and ca planes

SFFC Scale factor for residual compressive strength

Field Comments



AMODEL Material Model

1: Unidirectional layer model

2: Fabric layer model

PHIC Coulomb friction angle

E_LIMT Element eroding axial strain

S_DELM Scale factor for delamination criteria

OMGMX Limit damage parameter for elastic modulus

ECRSH Limit compressive volume strain for element eroding

EEXPN Limit tensile volume strain for element eroding

CERATE1 Coefficient for strain rate dependent strength properties

AM1 Coefficient for strain rate softening property for fiber in a direction

Field Comments


Materials238

MAT_COMPOSITE_MSC_DMG

Defines the material properties for a material model to simulate the progressive failure analysis for composite materials consisting of unidirectional and woven fabric layers.

Field Comments






EA Young’s Modulus - longitudinal direction

EB Young’s Modulus - transverse direction

EC Young’s Modulus - through thickness direction


GAB, GBC, GCA Shear Stress in ab bc, and ca directions






MACF Material Axes change flag:

= 1 no change (default)

= 2, switch material axes a and b

= 3, switch material axes a and c

= 4, switch material axes b and c







BETA Layer in-plane rotational Angle (degrees)

SAT Longitudinal Tensile Strength

SAC Longitudinal Compressive Strength

SBT Transverse Tensile Strength

SBC Transverse Compressive Strength

SCT Through thickness Tessile Strength

SFC Crush Strength

SFS Fiber mode shear strength

Sij Transverse Shear Strength ij

SFFC Scale factor for residual compressive strength

Field Comments

Materials240


MAT_MODIFIED_CRUSHABLE_FOAM

Defines the material properties for a material model to simulate crushable foam with optional damping, tension cutoff and strain rate effects. Unloading is fully elastic. Tension is treated as elastic-perfectly-plastic at the tension cutoff value.

AMODEL Material Model

1: Unidirectional

2: Fabric

PHIC Coulomb friction angle

E_LIMT Element eroding axial strain

S_DELM Scale factor for delamination criteria

OMGMX Limit damage parameter for elastic modulus

ECRSH Limit compressive volume strain

EEXPN Limit tensile volume strain

CERATEi Coefficient for strain rate dependent strength parameter, axial moduli, shear moduli, transverse moduli

Field Comments






Field Comments




MAT_QUASILINEAR_VISCOELASTIC

Defines the properties for a material model to simulate a quasi-linear, isotropic, viscoelastic material which represents biological soft tissue such as brain, kidney, etc.

E Young’s Modulus


TID Load Curve Id defining Yield Stress vs. Volumetric Strain

TSC Tensile Stress Cutoff

DAMP Rate sensitivity via damping coefficient

NCYCLE Number of cycles to determine volumetric strain rate

SRCLMT Strain rate change limit

Field Comments






K Bulk Modulus

LC1 Load Curve Id for the Relaxation function in shear

Field Comments


Materials242


LC2 Load Curve Id for the instantaneous Elastic response in shear

N No. of Prony series terms in fit

GSTART Starting value for least square fit

M No. of terms used to determine the instantaneous elastic response

S0 Strain output option to be plotted as component 7 in LS-TAURUS

0: Maximum principal strain

1: Maximum Magnitude of principal strain

2: Maximum Effective strain

E_MIN Minimum strain rate used to generate the load curve fron Ci

E_MAX Maximum strain rate used to generate the load curve fron Ci

GAMA1, GAMA2 Material failure parameters

KF Material failure parameter that controls the enclosed by the failure surface.

.LE 0, ignore failure criterion.

.GE. 0, use actual K value for failure criterion.

EH Damage parameter

FORM Formulation of Model.

=0 original model by Fung which relaxes to a zero stress state as time approaches to infinity.

= 1 Alternative model which relaxes to the quasistatice elastic response

C1 to C6 Coefficients of the instanteneous elastic response in compression and tension

Field Comments



MAT_HILL_FOAM

Defines the properties for a material model to simulate a highly compressible foam based on strain energy function, proposed by Hill. This model takes Poisson’s ratio effects into account.


Field Comments






K Bulk Modulus

N Material constant

MU Damping coefficient

LCID Load Curve Id defining Force per unit area vs. Stretch Ratio

FITTYPE Type of fit

1: Uniaxial

2: Biaxial

LCSR Load Curve Id defining uniaxial (or biaxial, depending on FITTYPE) Stress ratio vs. Transverse Stretch Ratio

R Mullinus effect model r coefficient

M Mullinus effect model m coefficient


Materials244

MAT_VISCOELASTIC_HILL_FOAM

Defines the properties for a material model to simulate a highly compressible foam based on strain energy function, proposed by Hill. with extensions to include large strain viscoelasticity proposed by Feng and Hallquist [2002].


Field Comments






K Bulk Modulus

N Material constant


LCID Load Curve Id defining Force per unit area vs. Stretch Ratio

FITTYPE Type of fit

1: Uniaxial

2: Biaxial

LCSR Load Curve Id defining uniaxial (or biaxial, depending on FITTYPE) Stress ratio vs. Transverse Stretch Ratio

LCVE Load Curve Id defining the Relaxation function in shear

NT No. of Prony series terms in fit

GSTART Starting value for least square fit



MAT_LOW_DENSITY_SYNTHETIC_FOAM

Defines the properties of rate independent low density foams exhibiting considerably reduced properties in the loading-unloading curve after the first loading cycle.

Field Comments






E Young’s Modulus

LCID1 Load Curve Id defining nominal Stress vs. Strain for the first loading cycle

LCID2 Load Curve Id defining nominal Stress vs. Strain for loading cycles after the first loading cycle is completed

HU Hysteric unloading factor between 0 and 1




FAIL Failure option after cutoff stress

0: Tensile Stress remains at cutoff

1: Tensile Stress resets to zero

Materials246


MAT_LOW_DENSITY_SYNTHETIC_FOAM_ORTHO

Defines the properties of rate independent low density foams exhibiting considerably reduced properties in the loading-unloading curve after the first loading cycle. This material model considers any orthotropic behavior after the first loading and unloading cycle of the material in the orthogonal directions.


0: No

1: Active

ED Optional Young’s relaxation modulus for rate effects

BETA1 Optional decay constant


REF Use reference geometry to initialize stress tensor

0: Off

1: On


RFLAG Rate type for input:

= 0, LCID1 and LCID2 should be input as functions of true strain rate

= 1, LCID1 and LCID2 should be functions of engineering strain rate

DIRT Strain rate averaging flag:

= 0, use weighted running average

.LE. 0, average the last eleven values

.GT. 0, average over the last DIRT time units

K


EH Damage parameter

Field Comments



Field Comments






E Young’s Modulus

LCID1 Load Curve Id defining nominal Stress vs. Strain for the first loading cycle

LCID2 Load Curve Id defining nominal Stress vs. Strain for loading cycles after the first loading cycle is completed

HU Hysteric unloading factor between 0 and 1




FAIL Failure option after cutoff stress

0: Tensile Stress remains at cutoff

1: Tensile Stress resets to zero

Materials248



0: No

1: Active

ED Optional Young’s relaxation modulus for rate effects

BETA1 Optional decay constant


REF Use reference geometry to initialize stress tensor

0: Off

1: On


RFLAG Rate type for input:

= 0, LCID1 and LCID2 should be input as functions of true strain rate

= 1, LCID1 and LCID2 should be functions of engineering strain rate

DIRT Strain rate averaging flag:

= 0, use weighted running average

.LE. 0, average the last eleven values

.GT. 0, average over the last DIRT time units

K


EH Damage parameter

Field Comments



MAT_SIMPLIFIED_RUBBER/FOAM

Defines the properties of a rubber amd foam model defined by a single uniaxial load curve or by a family of curves at discrete strain rates.

Field Comments






KM Linear Bulk Modulus


G Shear Modulus

SIGF Limit stress for frequency independent, frictional, damping

REF Use Reference Geometry (defined in *INITIAL_FOAM_REFERENCE_GEOMETRY) to initialize the stress tensor. 0 = ON ; 1 = OFF

PRTEN Tensile Poisson’s ratio.

= 0 indicates that PR/BETA will serve as Poisoon’s ratio for both tension and compression in shells. Otherwise, PR/BETA will serve as Poisoon’s ratio for compression in shells.


SW Specimen Width


Materials250


LCID Load Curve Id defining Force vs. Actual change in gauge length

TENSION Parameter to control rate effect

-1: Rate effects are treated for loading either in tension or in compression (but not for unloading)

0: Rate effects are treated for loading compressive loading only

1:Rate effects are treated identically for tension and compressive loading only

RTYPE Strain rate type

0: True

1: Engineering

AVGOPT Averaging option to determine strain rate (to reduce numerical noise)

0: Simple average of twelve time steps

1: Running 12-point average

PR/BETA If value is between 0.0 and 0.5 (exclusive), the value give here is taken as Poisson’s ratio. If value is exactly 0.0 (zero), an incompressible rubber like behavior is assumed, and a value of 0.495 is used inside the software. If zero Poisson’s ratio is desired, use a small value such as 0.001 for PR.

K Material failure parameter that controls the enclosed by the failure surface.

.LE 0, ignore failure criterion.

.GE. 0, use actual K value for failure criterion.


EH Damage parameter

Field Comments



MAT_SEISMIC_BEAM

Defines the properties of a material characterized by lumped plasticity to be developed at the ‘node 2’ end of Belytschko-Schwer beams. The plastic yield surface allows interaction between the two moments and the axial force.

Field Comments






E Young’s Modulus


AOPT Axial force option

0: Axial Load Curves are Collapse Load vs. Strain

NE. 0: Axial Load Curves are Collapse Load vs. Change in Length

Materials252

FTYPE Formulation type for interaction

1: Parabolic coefficients

2: Japanese Code, axial force and major axis bending

DEGRADE Flag for degrading moment behavior

0 = behavior as in previous versions

1 = Fatigue-type moment-rotation behavior

2 = FEMA-type moment-rotation behavior

IFEMA Flag for input of FEMA thresholds

= 0 No inputs ; 1 = Input of rotation thresholds only

=2 Input of rotation and axial strain thresholds

LCPMS Load Curve Id for Plastic Moment vs. Rotation about s at node 2

SFS Scale factor on s -moment at node 2

LCPMT Load Curve Id for Plastic Moment vs. Rotation about t at node 2

SFT Scale factor on t -moment at node 2

LCAT Load Curve Id for axial tensile yield force vs. total tensile strain (or elongation, see AOPT option)

SFAT Scale factor for axial tensile force

LCAC Load Curve Id for axial compressive force vs. strain/elongation

SFAC Scale factor for axial compressive force

ALPHA, BETA, GAMMA, DELTA, A, B

Parameters to define yield surface

FOFFS Force offset for Yield Surface

SIGY Yield Stress

D Depth of section used for interaction curve

W Width of section used for interaction curve

TF Flange Thickness of section used for interaction curve

TW Web Thickness of section used for interaction curve

PR1 - PR4 Plastic rotation thresholds 1 to 4

TS1 - TS4 Tensile axial strain hresholds 1 to 4

CS1 - CS4 Compressive axial strain hresholds 1 to 4

Field Comments



MAT_SOIL_BRICK

Defines the properties of clay like soils accurately.

Field Comments






RLAMDA, RKAPPA, RIOTA, RBETAi

Material coefficient

RMU Shape factor coefficient

RNU Poisson’s ratio

RLCID Load Curve Id referring to a curve defining up to ten pairs of ‘string-length’ vs. G/Gmax points.up to 10 points of string-length vs. Gmax

TOL User defined tolerance for convergence checking

PGCL Pre consolidation ground level

SUB-INC User defined strain increment size

BLK Elastic bulk stiffness of the soil

GRAV Gravitational acceleration


Materials254


MAT_DRUCKER_PRAGER

Defines the properties of materials such as soils modeled with the modified Drucker-Prager yield surface.

THEORY Version of material subroutine used

0 (default) = 1995 version (vectorized) ; 4 = 1995 version (unvectorized)

RVHNH Anisotropy parameter

XSICRIT, ALPHA Anisotropy parameters

RVH Anisotropy ratio (Ev/Eh)

RNU21 Anisotropy ratio (ν2/ν1)

ANISO_4 Anisotropy parameter

Field Comments






GMOD Elastic Shear Modulus


RKF Failure surface shape parameter

Field Comments




PHI Angle of friction (radians)

CVAL Cohesive Value

PSI Dilation angle (radians)

STR_LIM Factor for calculating minimum shear strength of material which is calculated as STR_LIM*CVAL

GMODDP Depth at which shear modulus is correct

PHIDP Depth at which friction angle is correct

CVALDP Depth at which cohesive value is correct

PSIDP Depth at which dilation angle is correct

GMODGR Gradient at which shear modulus increases with depth

PHIGR Gradient at which friction angle increases with depth

CVALGR Gradient at which cohesive value increases with depth

PSIGR Gradient at which dilation angle increases with depth

Field Comments


Materials256

MAT_RC_SHEAR_WALL

Defines the properties of materials to model cyclic shear loading of reinforced concrete walls (available only for shell elements).

Field Comments






E Young’s Modulus


TMAX Ultimate shear stress



Fc Unconfirmed compressive strength of Concrete

PREF Percent reinforcement

FYIELD Yield stress of reinforcement

SIG0 Overburden stress

UNCONV Unit conversion factor, to compute ultimate tensile stress of Concrete

ALPHA Shear span factor

FT Cracking stress in direct tension

ERIENF Young’s Modulus for reinforcement

A, B, C, D, E Hysteresis constants to determine shape of the hysteresis loops

F Strength gradient factor

Yi Shear strain points on stress vs. strain curve

Ti Shear stress points on stress vs. strain curve











BETA Layer in-plane rotational Angle

Field Comments


Materials258

MAT_CONCRETE_BEAM

Defines an elasto-plastic material with an arbitrary stress-strain curve and arbitrary strain rate dependency. Also, failure based on plastic strain or a minimum time step can be defined.

Field Comments






E Young’s Modulus


SIGY Yield Stress



FAIL Failure Flag


LCSS Load Curve Id defining Effective Stress vs. Effective Plastic Strain in compression

LCSR Load Curve Id defining Strain rate effects on Yield Stress



MAT_GENERAL_SPRING_DISCRETE_BEAM

Defines the properties of materials with elastic and elastoplastic springs with damping to be represented by discrete beam elements using six springs, each acting along one of the six local degrees-of-freedom.

NOTEN No-tension flag

0: Takes tension

1: Does not take Tension

2: Takes tension upto value given by TENCUT (Tension cutoff)

TENCUT Tension cutoff stress

SDR Stiffness degradation factor

Field Comments


Materials260

For elastic behavior, use a load curve of yield force or moment versus displacement or rotation. For inelastic case, use a load curve of yield force or moment versus plastic deflection or rotation.


Materials262


Field Comments






DOFi Active degree-of-freedom

TYPEi Behavior

0: Elastic

1: Inelastic

Ki Elastic loading/unloading stiffness

Di Optional viscous damping coefficient

CDFi Compressive displacement at failure

TDFi Tensile displacement at failure

FLCIDi Load Curve Id defining Force (or Moment) vs. Displacement for nonlinear elastic (TYPE1 = 0). For inelastic behavior, this curve defines the yield force vs. plastic deflection.

HLCIDi Load Curve Id defining Force vs. Relative Velocity

C1_i, C2_i Damping coefficients

DLEi Scale factor for time unit

GLCIDi Load Curve Id defining scale factor vs. deflection for HLCIDi



MAT_SEISMIC_ISOLATOR

Defines the properties of materials used as sliding and elastometric seismic isolation bearings. This material model uses a bi-directional coupled plasticity theory (available only for discrete beam elements).

Field Comments






A, GAMMA, BETA Non dimensional variable

DISPY Yield displacement

STIFFV Vertical stiffness

ITYPE Type

0: Sliding

1: Elastomeric

PRELOAD Vertical preload

DAMP Damping ratio

MXi Moment factor at end i in local x direction

MYi Moment factor at end i in local y direction

FMAX Maximum dynamic friction coefficient

Materials264


DELF Difference between maximum and Static Friction coefficient

AFRIC Velocity multiplier in sliding friction equation

RADX Radius for sliding in local x direction

RADY Radius for sliding in local y direction

RADB Radius of retaining ring

STIFFL Stiffness for lateral contact against retaining ring

STIFFTS Stiffness for tensile vertical response (sliding)

FORCEY Yield force

ALPHA Ratio of post and pre yielding stiffness

STIFFT Stiffness for tensile vertical response (elastomeric)

DFAIL Lateral displacement at which isolator fails

FMAXYC Maximum dynamic friction coefficient in compression in local y-direction

FMAXXT Maximum dynamic friction coefficient in tension in local x-direction

FMAXYT Maximum dynamic friction coefficient in tension in local y-direction

YLOCK Stiffness locking the local y- displacement (optional in single axis sliding)

Field Comments



MAT_JOINTED_ROCK

Defines the properties of jointed rocks.

Field Comments






GMOD Elastic Shear Modulus


RKF Failure surface shape parameter

PHI Angle of friction (radians)

CVAL Cohesive Value

PSI Dilation angle (radians)

STR_LIM Factor for calculating minimum shear strength of material which is calculated as STR_LIM*CVAL

NPLANES No of joint planes

Materials266


ELASTIC Flag for Elastic Behavior

0: Non elastic

1: Elastic

LCCPDR Load Curve Id for extra cohesion for parent material (dynamic relaxation)

LCCPT Load Curve Id for extra cohesion for parent material (transient)

LCCJDR Load Curve Id for extra cohesion for joints (dynamic relaxation)

LCCJT Load Curve Id for extra cohesion for joint material (transient)

LCSFAC Load Curve Id giving factor on Strength vs. Time

GMODDP Depth at which shear modulus is correct

PHIDP Depth at which friction angle is correct

CVALDP Depth at which cohesive value is correct

PSIDP Depth at which dilation angle is correct

GMODGR Gradient at which shear modulus increases with depth

PHIGR Gradient at which friction angle increases with depth

CVALGR Gradient at which cohesive value increases with depth

PSIGR Gradient at which dilation angle increases with depth

DIPi Angle (degrees) of plane below the horizontal

STRIKEi Plan view angle (degrees) of downhill vector drawn on the plane

CPLANEi Cohesion for shear behavior on plane i

FRPLANEi Friction angle for shear behavior on plane i

TPLANEi Tensile strength across plane i

SHRMAXi Maximum shear stress on plane i

LOCALi DIP and STRIKE Coordinate System flag

0: with respect to Global axes

1: with respect to element local axes

Field Comments



MAT_SPRING_ELASTIC

Defines the properties of a translational or rotational elastic spring placed between two nodes. Only one degree of freedom is connected.


MAT_DAMPER_VISCOUS

Defines the properties of translational and rotational dampers located between two nodes. Only one degree of freedom is connected.

Field Comments





K Elastic Stiffness (Translational or Rotational)

Field Comments





DC Damping Constant (Force/Displacement rate or Moment/Rotation rate)


Materials268


MAT_SPRING_ELASTOPLASTIC

Defines the properties of discrete springs providing an elastoplastic translational or rotational spring with isotropic hardening located between two nodes. Only one degree of freedom is connected.


Field Comments





K Elastic Stiffness (Translational or Rotational)

KT Tangent Stiffness

FY Yield Force or Moment




MAT_SPRING_NONLINEAR_ELASTIC

Defines the properties of discrete springs providing a nonlinear elastic translational or rotational spring with arbitrary force versus displacement and moment versus rotation data. Only one degree of freedom is connected.


Field Comments





LCD Load Curve Id defining Force vs. Displacement or Moment vs. Rotation

LCR Load Curve Id defining Scale factor on Force or Moment as a function of relative velocity, or rotational velocity respectively


Materials270

MAT_DAMPER_NONLINEAR_VISCOUS

Defines the properties of discrete dampers providing a viscous translational or rotational damper with arbitrary force versus velocity or a moment versus rotational velocity data. Only one degree of freedom is connected.


MAT_SPRING_GENERAL_NONLINEAR

Defines the properties of discrete springs providing a general nonlinear translational or rotational spring with arbitrary loading and unloading data. It also considers hardening or softening. Only one degree of freedom is connected.

Field Comments





LCDR Load Curve Id defining the Force vs. rate of Displacement or Moment vs. rate of Rotation relationship

Field Comments







MAT_SPRING_MAXWELL

Defines the properties of discrete springs providing a three Parameter Maxwell Viscoelastic translational or rotational spring. Only one degree of freedom is connected.


LCDL Loading Curve Id for Force vs. Displacement or Moment vs. Rotation

LCDU Unloading Load Curve Id for Force vs. Displacement or Moment vs. Rotation

BETA Hardening parameter

TYI Initial Yield force in tension

CYI Initial Yield force in compression

Field Comments





K0 Short term stiffness

KI Long term stiffness

BETA Decay constant

TC Cutoff time. After this time a constant force/moment transmitted

Field Comments


Materials272


MAT_SPRING_INELASTIC

Defines the properties of discrete springs and dampers providing an inelastic tension or compression only, translational or rotational spring.


FC Force/Moment after cutoff time

COPT Time implementation option

0: Incremental time change

1: Continuous time change

Field Comments





LCFD Load Curve Id defining the Force/Torque vs. Displacement/Twist relationship

KU Unloading Stiffness

CTF Flag for compression/tension

-1: Tension only

1: Compression only (Default CTF value is 0, which is same as 1)

Field Comments




MAT_SPRING_TRILINEAR_DEGRADING

Defines the properties of concrete shear walls under seismic loading modelled as discrete elements. It represents cracking of the concrete, yield of the reinforcement, and overall failure.


Field Comments





DEFL1 Deflection at point where concrete cracks

F1 Force corresponding to DEFL1

DEFL2 Deflection at reinforcement yield


DEFL3 Deflection at complete failure


FFLAG Failure Flag


Materials274

MAT_SPRING_SQUAT_SHEARWALL

Defines the properties of squat shear walls modelled as discrete elements. This material model allows concrete cracking, reinforcement yield, and ultimate strength, followed by degradation of strength, leading finally to collapse.


Field Comments





A14, B14, C14, D14, E14

Material coefficient

LCID Load Curve Id referencing the maximum strength envelope curve

FSD Sustained strength reduction factor



MAT_SPRING_MUSCLE

Defines the properties for discrete springs and dampers. This is a Hill-type muscle model with activation.


Field Comments





L0 Initial muscle length

VMAX Maximum CE shortening velocity

SV Scale factor for Vmax vs. Active State

A Scale factor for Activation Level vs. Time function

FMAX Peak isometric force

TL Scale factor for Active tension vs. length function

TV Scale factor for Active tension vs. velocity function

FPE Scale factor for Force vs. length function, for parallel elastic element

LMAX Relative length at FPE=FMAX

KSH Constant governing the exponential rise of FPE

LCID_SV Load Curve Id defining Vmax vs. active state

LCID_A Load Curve Id defining Active level vs. Time function

LCID_TL Load Curve Id defining Active tension vs. Length function

LCID_TV Load Curve Id defining Active tension vs. velocity function

LCID_FPE Load Curve Id defining Force vs. Length function


Materials276

MAT_THERMAL_ISOTROPIC

Defines isotropic thermal properties of materials in coupled structural/thermal and thermal only analyses.


MAT_THERMAL_ORTHOTROPIC

Defines orthotropic thermal properties in coupled structural/thermal and thermal only analyses.

Field Comments





TRO Thermal Density

TGRLC Thermal generation rate value

TGMULT Thermal generation rate multiplier

TLAT Phase chnage temperature

HLAT Latent heat

HC Heat capacity

TC Thermal conductivity



Field Comments





TRO Thermal Density








HLAT Latent heat

Materials278


MAT_THERMAL_ISOTROPIC_TD

Defines temperature dependent isotropic thermal properties in coupled structural/thermal and thermal only analyses.

K1, K2, K3 Thermal conductivity in local x, y and z, respectively






Field Comments





TRO Thermal Density


Field Comments




MAT_ORTHOTROPIC_TD

Defines temperature dependent orthotropic thermal properties in coupled structural/thermal and thermal only analyses.



HLAT Latent heat

LC_C Load Curve defining Heat capacity (C) Vs. Temperature

LC_K Load Curve defining Thermal Conductivity (K) Vs. Temperature

Field Comments


Materials280


Field Comments





TRO Thermal Density






2: Globally orthotropic with material axis determined by vectors below.

LC_C Load Curve defining Heat capacity Vs. Time

LC_KX Load Curve defining Thermal conductivity in local X Vs. Time

LC_KY Load Curve defining Thermal conductivity in local Y Vs. Time

LC_KZ Load Curve defining Thermal conductivity in local Z Vs. Time








MAT_THERMAL_ISOTROPIC_PHASE_CHANGE

Defines temperature dependent isotropic properties with phase changes in coupled structural/thermal and thermal only analyses.

Field Comments





TRO Thermal Density



LC_C Load Curve defining Heat capacity Vs. Temperature

LC_K Load Curve defining Thermal conductivity Vs. Temperature

SOLT Solid Temperature

LIQT Liquid Temperature

LH Latent Heat

Materials282


MAT_THERMAL_ISOTROPIC_TD_LC

Defines temperature dependent isotropic thermal properties by specifying a load curve in coupled structural/thermal and thermal only analyses.


Field Comments





TRO Thermal Density



HCLC Load Curve Id specifying Heat capacity vs. Temperature

TCLC Load Curve Id specifying Thermal conductivity vs. Temperature

TGRLCID Load Curve Id specifying Thermal generation rate curve number



273Properties

Properties

Properties274

Properties

OverviewTypical properties include cross-sectional properties of beam elements, thicknesses of plate and shell elements, element integration rules, and hourglass controls. Properties are assigned to the elements of a specified part or element type, either directly to the elements, or indirectly through the part to which the elements belong.

Element Types and Associated Properties

Thin Shell Elements

Two-dimensional elements, commonly referred to as plate and shell elements, are used to represent areas in your model where one of the dimensions is small in comparison to the other two. As shown Figure 1 the thickness is substantially less than dimensions a or b.

Figure 1 Typical Plate Element

ELEMENT_SHELL - General-purpose plate elements (4-noded) capable of carrying in plane force, bending forces, and transverse shear force. The triangular element is defined by repeating the third for the fourth node. This family of elements are the most commonly used shell elements in the SimXpert crash element library. These are the element types generated by the Automesher.

275PropertiesProperties

*SECTION_SHELL - The thin shell elements are commonly referred to as the plate and shell elements within SimXpert. Their properties, are defined using the *SECTION_SHELL entry. The format of the *SECTION_SHELL entry is as follows:

Properties276

Field Contents

SECID Section ID, to be referred by parts

ELFORM Element formulation options

= 1: Hughes-Liu

= 2: Belytscho-Tsay

= 3: BCIZ triangular shell

= 4: C0 triangular shell

= 5: Belytscho-Tsay membrane

= 6: S/R Hughes-Liu

= 8: Belytscho-Leviathan shell

= 9: Fully integrated Belytscho-Tsay membrane

= 10: Belytscho-Wong-Chiang

= 11: Plane stress (x-y plane)

= 12: Fast (co-rotational) Hughes-Liu

= 13: Plane strain (x-y plane)

= 14: Axisymmetric solid (y-axis of symmetry) - area weighted

= 15: Axisymmetric solid (y-axis of symmetry) - volume weighted

= 16: Fully integrated shell element

= 17: Fully integrated DKT triangular shell element

= 18: Fully integrated DK quadrilateral/triangular shell element

= 20: Fully integrated linear assumed strain C0 shell

= 21: Fully integrated linear assumed strain (5 DOF per node) C0 shell

= 22: Linear shear panel element (3 DOF per node)

SHRF Shear correction factor (value of 5/6 is recommended for solid plate)

NIP Number of through thickness integration points


PROPT Printout options

= 0: Average resultants and fiber lengths

= 1: resultants at plan points and fiber lengths

= 3: Resultants, stresses at all points, fiber lengths

QR Quadrature rule

LT 0.: Absolute value is used as the Quadrature rule

EQ. 0.: Gauss Rule (up to five points permitted)

EQ. 1.: Trapezoidal Rule

ICOMP Flag for orthotropic/anisotropic layered composite material model

= 0: Homogeneous

=1: Composite

SETYP 2D solid element type (defined for ELFORM 13, 14, and 15)

= 1: Lagrangian

= 2: Eulerian (single material with voids)

= 3: ALE

T1 Shell thickness at node 1

T2, T3, T4 Shell thickness at nodes 2, 3, and 4 respectively

NLOC Location of reference surface normal to s axis (Hughes-Liu elements: ELFORM = 1 or 6)

MAREA Nonstructural mass per unit area

IDOF Applies to shell element types 25 and 26.

.EQ. 1(default): The thickness field is continuous across the element edges for metal-forming applications.

.EQ. 2: The thickness field is discontinuous across the element edges. This is necessary for applications such as crashworthiness where shell intersections, sharp included angles, and non-smooth deformations exist.

EDGSET Edge node set, required for shell type seatbelts.

AFAC Smoothing weight factor - simple average (No smoothing if value is -1.)

BFAC Smoothing weight factor - volume weighting

Field Contents

Properties278

The element coordinate systems for the shell element is shown in Figure 2. The orientation of the element coordinate system is determined by the order of the connectivity for the nodes. The element z-axis, often referred to as the positive normal, is determined using the right-hand rule. Therefore, if you change the order of the nodal connectivity, the direction of this positive normal also reverses. This rule is important to remember when applying pressure loads or viewing the untransformed element forces or stresses. Untransformed directional element stress plots may appear strange when they are displayed by the postprocessor in SimXpert because the normals of the adjacent elements may be inconsistent. Remember that components of forces, moments, and element stresses are always output in the element coordinate system.

Figure 2 Thin Shell Element Geometry and Coordinate Systems


CFAC Smoothing weight factor - isoparametric

DFAC Smoothing weight factor - equipotential

EFAC Smoothing weight factor - equilibrium

START Start time for smoothing

END End time for smoothing

AAFAC ALE advection factor

DX, DY Normalized dilatation parameters of the kernel function in X and Y directions respectively

ISPLINE Replaces choice for the EFG kernel functions definition in *CONTROL_EFG.

IDILA Replaces choice for the normalized dilation parameter definition in *CONTROL_EFG.

IRID Integration Rule Id (User defined)

Field Contents


Thick Shell Elements

If the thickness dimension of your component is small, but not too small, in comparison to the other two, dimensions, you can model it with thick shell elements.

Figure 3 Typical Plate Element

*ELEMENT_TSHELL - Eight noded thick shell element useful for modeling thick plated components. Unlike the thin shell element, *ELEMENT_SHELL which represents the plate through the middle surface, and thickness, the 8-noded thick shell element represents plate as a hexahedron, the first four nodes representing the bottom surface, and the last four nodes representing the top surface. The thick

Properties280

shell wedge element is defined by repeating the third for the fourth node, and repeating the seventh for the eighth node.

Figure 4 Thick Shell Element Connectivity


SECTION_TSHELL

The properties of the thick shell elements are defined using the *SECTION_TSHELL entry. The format of the *SECTION_TSHELL entry is as follows:

Field Contents



= 1: 1point reduced integration (Default)

= 2: Selective reduced 2X2 in plane integration

= 3: Assumed strain 2X2 in plane integration

SHRF Shear correction factor (a value of 5/6 recommended for solid section plate)

NIP Number of through thickness integration points. (If NIP = 0, the Default value of 2 is used)

PROPT Printout options

= 0: Average resultants and fiber lengths

= 1: resultants at plan points and fiber lengths

= 3: Resultants, stresses at all points, fiber lengths

Properties282

The orientation of the element coordinate system is determined by the order of the connectivity for the nodes. The element z-axis (the thickness direction) often referred to as the positive normal to the face connected by nodes n1, n2, n3, and is determined using the right-hand rule (cross product of edge vectors n1-n2 and n1-n3). Therefore, if you change the order of the nodal connectivity, the direction of this positive normal also reverses. This rule is important to remember when applying pressure loads or viewing the untransformed element forces or stresses. Untransformed directional element stress plots may appear strange when they are displayed by the postprocessor in SimXpert because the normals of the adjacent elements may be inconsistent. Remember that components of forces, moments, and element stresses are always output in the element coordinate system.


Three-Dimensional Elements

Whenever you need to model a structure that does not behave as a bar or plate structure under the applied loads, you need to use one or more of the three-dimensional elements. The three-dimensional elements are commonly referred to as solid elements. Typical engineering applications of solid elements include engine blocks, brackets, and gears.

The Solid Elements in the Crash Workspace Include the Following:1. 8 noded hexahedron

2. 6 noded pentahedron (degenerated from the 8-node hexahedron, by repeating node 4 for the last four nodes (n1, n2, n3, n4, n4, n4, n4, n4, n4)

3. 4 noded tetrahedron (degenerated from the 8-node hexahedron, by repeating node 5 for the sixth node, and repeating node 7 for the eighth node (n1, n2, n3, n4, n5, n5, n6, n4, n6)

QR Quadrature rule

LT 0.: Absolute value is used as the Quadrature rule

EQ. 0.: Gauss Rule (up to five points permitted)

EQ. 1.: Trapezoidal Rule

ICOMP Flag for orthotropic/anisotropic layered composite material model

= 0: Homogeneous

=1: Composite


B1 Material angle (β1) at first integration point. This angle is measured with respect to the element edge n1-n2.

Field Contents


4. 10 noded tetrahedron

Figure 5 Solid Elements

Properties284

SECTION_SOLID

The properties of the solid elements are entered on the *SECTION_SOLID form shown below:

Field Contents

Title Unique name identifying the section.




= 0: 1 point co-rotational for *MAT_MODIFIED_HONEYCOMB

= 1: Constant stress solid element (Default)

= 2: Fully integrated S/R solid

= 3: Fully integrated quadratic 8 node element with nodal rotations

= 4: S/R quadratic tetrahedron with nodal rotations

= 5: 1 point ALE

= 6: 1 point Eulerian

= 7: 1 point Eulerian ambient

= 8: acoustic

= 9: 1 point co-rotational for *MAT_MODIFIED_HONEYCOMB

= 10: 1 point tetrahedron

= 11: 1 point ALE multi-material element

= 12: 1 point integration with single material and void

= 13: 1 point nodal sure tetrahedron for bulk forming

= 14: 8 point acoustic

= 15: 2 point pentahedron element

= 16: 5 point 10 noded tetrahedron

= 18: 8 point enhanced strain solid element for linear statics only

AET Ambient element type (foe ELFORM = 7, 11 or 12)

= 3: pressure outflow

= 4: pressure inflow (Default for ELFORM = 7)

AFAC Smoothing weight factor - simple average (if value is -1, smoothing turned off)

BFAC Smoothing weight factor - volume weighting

CFAC Smoothing weight factor - isoparametric

Field Contents

Properties286

DFAC Smoothing weight factor - equipotential

START End time for smoothing

END Start time for smoothing

AAFAC ALE advection factor

DX, DY, DZ Normalized dilatation parameters of the kernel function in X, Y, and Z directions respectively

ISPLINE Replaces choice for the EFG kernel functions definition in *CONTROL_EFG..

.EQ. 0: Cubic spline function (default)

.EQ. 1: Quadratic spline function

.EQ. 2: Cubic spline function with cubic shape

IDILA Replaces choice for the normalized dilation parameter definition in *CONTROL_EFG..

.EQ. 0: Maximum distance based on the background elements

.EQ. 1: Maximum distance based on the sourounding nodes

IEBT Essential boundary condition treatment:

.EQ. 1: Full transformation method

.EQ. -1: w/o transformation

.EQ. 2: Mixed transformation method

.EQ. 3: Coupled FEM/EFG method

.EQ. 4: Fast transformation method

.EQ. -4: w/o transformation

.EQ. 5: Fluid particle method for E.O.S and *MAT_ELASTIC_FLUID materials

Field Contents



One-Dimensional Elements

A one-dimensional element is one in which the properties of the element are defined along a line or curve. Typical applications for the one-dimensional element include trusses, beams, and stiffeners. One-

IDIM Domain integration method:

.EQ. 1: Local boundary integration (default)

.EQ. 2: Two-point gauss integration

.EQ. 3: Improved gauss integration for IEBT = 4 or -4

TOLDEF Deformation tolerance for the activation of adaptive EFG Semi-Lagrangian and Eulerian kernel.

= 0.0: Lagrangian kernel

> 0.0: Semi-Lagrangian

<0.0: Eulerian kernel.

Field Contents

Properties288

dimensional elements discussed in this chapter include 3D beams, trusses, 2D axisymmetric shells, and 2D plane strain beam elements.

Figure 6 Beam Elements

SECTION_BEAM


The properties of the one dimensional elements are entered on the *SECTION_BEAM form shown below:

Field Contents



= 1: Hughes-Liu with cross section integration (Default)

= 2: Belytscho-Schwer resultant beam

= 3: Truss resultant

= 4: Belytscho-Schwer full cross-section integration

= 5: Belytscho-Schwer tubular beam full cross-section integration

= 6: Discrete beam/cable

= 7: 2D plane strain shell element (xy plane)

SHRF Shear factor (5/6 recommended for rectangular section beam)

Properties290


QR Quadrature rule or rule number for user defined integration rule

= 1: 1 point integration

= 2: 2X2 Gauss quadrature (default beam)

= 3: 3X3 Gauss quadrature

= 4: 3X3 Lobatto quadrature

= 5: 4X4 Gauss quadrature

= -n: where the absolute value of n is the number of the user defined rule.

CST Cross section type (Not needed for truss, resultant beam, discrete beam, and cable elements)

= 0: rectangular

= 1 Tubular (circular only)

= 2 Arbitrary (User defined integration rule)

SCOOR Location for triad for tracking the rotation of the discrete beam element

NSM Nonstructural mass per unit length

TS1 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in s direction at node 1

TS2 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in s direction at node 2

TT1 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in t direction at node 1

TT2 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in t direction at node 2

NSLOC Location of reference surface normal to s axis (for Hughes-Liu beam elements only)

NTLOC Location of reference surface normal to t axis (for Hughes-Liu beam elements only)


Field Contents


Discrete Elements

Discrete elements in SimXpert Crash comprise of spring and damper elements used between two nodes, or a node and ground.

SECTION_DISCRETE

The properties of the discrete elements are entered on the *SECTION_DISCRETE form shown below:


Seatbelt Elements

Seat belt elements are elements with single degree of freedom, connecting two nodes.

Field Contents


DRO Displacement/Rotation Option:

=0 for translational spring or damper

=1 for torsional spring or damper

KD Dynamic magnification vector

V0 Test velocity

CL Clearance

FD Failure deflection (twist, for DRO = 1. Negative for compression, positive for tension

CDL Deflection (twist, for DRO = 1) limit in compression

TDL Deflection (twist, for DRO = 1) limit in tension

Properties292

SECTION_SEATBELT

The properties of the seat belt elements are entered on the *SECTION_SEATBELT form shown below:


Mass Elements

Mass elements are used to defined lumped masses to nodes. In SimXpert crash workspace, the mass associated with the mass elements are assigned directly to the mass element, and hence no properties are needed to be created.


Element IntegrationSimXpert crash Workspace normally uses the recommended integration through thickness of beams and shell elements. However, you can use other through-thickness integration rules using

• *INTEGRATION_BEAM for defining through thickness integration rules for the beam elements

• *INTEGRATION_SHELL for defining through thickness integration rules for both the thin and thick shell elements.


Field Contents



HourglassingThe advantage of the reduced integration elements is that the strains and stresses are calculated at the location that provide optimal accuracy, the so-called Barlow points. The reduced integration elements also tend to underestimate the stiffness of the element which often gives better results in a typically overly-stiff finite element analysis displacement method. An additional advantage is that the reduced number of integration points decreases CPU time and storage requirements. The disadvantage is that the reduced integration procedure may admit deformation modes that cause no straining at the integration points. These zero-energy modes cause a phenomenon called “hourglassing,” where the zero energy mode starts propagating through the mesh, leading to inaccurate solutions. This problem is particularly severe in first-order quadrilaterals and hexahedrals. To prevent these excessive deformations, an additional artificial stiffness is added to these elements. In this so-called hourglass control procedure, a small artificial stiffness is associated with the zero-energy modes. This procedure is used in many of the solid and shell elements in SimXpert crash Workspace Use the *HOURGLASS keyword data to define hourglass and bulk viscosity properties which are referenced via the HGID in the *part command..

Figure 7 Hourglassing


Properties294

293Meshing and Element Creation

Meshing and Element Creation

Meshing and Element Creation294

Meshing and Element Creation

Modeling GuidelinesFinite element modeling in many ways is more like an art than a science since the quality of the results is dependent upon the quality of your model. One of the more common errors that a beginning finite element analyst makes in modeling is to simply simulate the geometry rather than to simulate both the geometry and the physical behavior of the real structure. The following modeling guidelines are provided to put a little more science back into the art of finite element modeling:

• Choosing the right element.

• Mesh transitions.

The above guidelines are by no means complete; however, they do serve as a good starting point. There is no better substitute for good modeling than experience. It is also good modeling practice to simulate and validate a new capability or a feature that you have not used before with a small prototype model before applying this feature to your production model. Model verification techniques are covered in Quality Checks, 297.

SimXpert contains a large library of structural elements. In many situations several elements are capable of modeling the same structural effects. The criteria for the selection of an element may include its capabilities (for example, whether it supports anisotropic material properties), the amount of time required to run an analysis (in general, the more DOF an element has, the longer it runs), and/or its accuracy.

In many cases the choice of the best element for a particular application may not be obvious. For example, in the model of a space frame, you may choose to use truss elements if bending or torsional stiffness is unimportant or to use the beam elements with axial, bending and torsional stiffness. You may even choose to represent the members with built-up assemblies of plate or solid elements. The choice of which type and number of elements to use depends primarily on your assessment of the effects that are important to represent in your model and on the speed and accuracy you are willing to accept.

In this context, it is critical that you have a fairly good idea of how the structure will behave prior to generating your finite element model. The best source of such insight is usually experience with similar structures or components. In other words, understanding the load path is crucial in the selection of the appropriate element. In addition, a few hand calculations can usually provide a rough estimate of stress intensities. Such calculations are always recommended. If you do not have a fairly good idea of how the structure will behave, you may be misled by incorrect results due to errors or incorrect assumptions in your input data preparation.

The following guidelines are provided to help you in selecting the “right” element for your task.

295Meshing and Element CreationMeshing and Element Creation

Avoid highly skewed elements (see Figure 1). The angle should be as close to 90 degrees as possible.

Figure 1 Highly Skewed Element

Aspect ratio is defined as (length/width). Very high aspect ratio (see Figure 2) should also be avoided in areas where there is a high stress gradient.

Figure 2 Element with High Aspect Ratio

Warping is a measure of the amount the element deviates from being planar (see Figure 3). Element warping should be minimized.

Figure 3 Highly Warped Element

Mesh Transitions

Mesh transition can be a complicated subject. It may simply be used to refine the mesh in a particular area, connect different element types (for example, a CBAR element to a solid element), or provide transitions required to model the geometry of the structure. Two guidelines for mesh transitions are as follows:

1. Never place a mesh transition in an area of interest or in an area where there is a large variation in stress.

2. Mesh transitions should be located away from the areas of interest in a region.

α

α

l ω⁄

l

ω

Element Mid-Plane


Due to incompatibilities between finite element types, any transition between different element types (even a transition from quadrilateral to a triangular elements) can result in local stress anomalies. Normally, these stress anomalies are localized and dissipate quickly as you move away from the transition. However, a problem arises when the transition occurs in an area of interest. In this case, the local stress rises (or decreases) due to the effect of the transition; in other words, the results may be conservative (or non-conservative) in an area near a transition. However, if this localized stress variation occurs away from areas of interest, the increase (or decrease) in stress caused by the transition should cause no concern.

• Transition from a Coarse Mesh to a Fine Mesh

The transition from a coarse mesh to a fine mesh, or vice versa, may not always be an easy task. One common method of performing a transition is to use an intermediate belt of triangular elements as shown in Figure 4.

Figure 4 Mesh Transition

Mesh ControlBefore you create elements, you should first specify a default mesh size by selecting Element Options from the Elements menu. Mesh sizes can also be set interactively using Mesh Size from the Elements menu. In addition you can also define hard points on curves or surfaces to ensure that a node is placed at that location. You do this using Create Hard Points from the Geometry menu. Mesh should have high density in areas of large stress gradients.

Meshing

Automeshing

You can use the selections under Automeshing to create multiple elements on geometry.

• Automesh - Used to create quadrilateral and triangular plate/shell elements on surfaces.

• Solid Mesher - Used to create a tetrahedral mesh inside bounding surfaces

• Interactive Mesh Size - Interactively modifies the number of elements along a selected curve

Q4 Q4

Q4 Q4

Q4 Q4

Q4 Q4

Q4

Q4

T3

T3

T3

T3

T3

T3


Manual Meshing

You can use the selections under Manual Meshing to create mesh without having surfaces.

• 2-3-4 Line Mesh - Creates a mapped mesh by selecting 2,3, or 4 bounding curves. User can modify the number of elements to be created on each curve. Set or modify the mesh elements parameters using Params button from the pick menu.

• 3-4 Point Mesh - Creates mesh between the 3 or 4 selected points. You can specify the number of elements to be created between each pair of selected points. Points should be selected in a circular manner.

• Drag Mesh - Creates a solid or shell mesh by dragging elements or nodes along a specified vector or curve.

• Flange Creation - Creates a flange by dragging selected nodes through a specified width and angle.

• Linear Solid Mesh - Creates solid elements between two groups of shell elements.

• Refine Mesh - Refines the selected mesh region to specified edge length, while maintaining element connectivity with congruent elements.

• Spin Mesh - Creates solid or shell elements by rotating shell elements or nodes through a specified angle about a vector.

Merge Coincident NodesNodes along common edges of adjoining geometry entities need to match. If these nodes are not coincident, your model will have free edges or faces at these points. Always merge coincident nodes before analyzing your model using Merge Coincident Nodes from the Node menu.

Quality Checks

Free Edges

You can check that your model has completed merging coincident nodes by displaying free edges in your model. In Figure 5 the model is shown with free edges displayed by selecting Highlight FE Boundary from the View menu.The picture on the left shows the model with a solid horizontal line running through the middle. This indicates that a free edge exists there and the top and bottom are not connected. The


picture on the right shows the model after the coincident nodes have been merged. The model is now one continuos piece.I

Figure 5 Free Edge Check - Before and After Merge Coincident Nodes

Consistent Plate Normals

You can check the orientation of your plate elements using the Normals selection from the Element menu. When the pick box appears, in the Mode list, click Show Normal then click All. In Figure 6 you can see that these elements do not have consistent normals.

Figure 6 Inconsistent Normals

Free (unconnected) edge

Before After


You can enforce consistent normals by now clicking Fix Normal in the Mode list and then selecting a reference element with the desired normal direction. You could also click Rev. Normal and then select the elements on which to reverse normals.

Figure 7 Consistent Normals

To turn off the display of normal vectors click Hide Normal in the Mode list then click All.

Element Shape Checks

The types of quality checks that SimXpert can perform on shell elements can be seen on the following form. It is accessed by selecting Quality/Quality from the Elements menu.

• Warp check: Evaluates how far out of plane the element ‘bends’. Warp is computed by determining the angle between the normals of 2 triangular regions superimposed on the element. This check is also applicable to quad faces of solid elements.

• Taper check: Compares the ratios of the lengths of opposite edges of an element.

• Skew check: Compares the maximum angles between the element diagonals.


• Interior Angle check: Evaluates the interior angles measured at each of the four (or 3) corner nodes.

If any element exceeds minimum or maximum tolerance levels specified for an element check, it is considered to have failed that test.

SimXpert can compute a Quality Index which is a weighted composite of all the selected quality checks. You can toggle the display of the Quality Index from the Bottom Block by selecting Fringes On/Off from the FE-Grafix menu.

Elements that violate any of the activated quality criteria will be displayed in magenta.

Those elements color-coded red to orange have marginal quality. You can further investigate which specific tests your elements may be failing by selecting the individual quality measure from the FE-Qual


menu and your display will update accordingly. The following image shows the model now color-coded based on Warpage.

Once again, failed elements are shown in magenta. Elements with a high value that does not exceed the threshold are color-coded red or orange.

Tools to Help Fix Poorly Shaped Elements• Manual - Element / Quality / Manual Fix - allows you to select a node and drag it to a new

location. Element color coding will change in real time to feed back how the element’s quality is changing. Click the middle mouse button to finalize the new nodal location.


• Mesh Quality - Element / Quality / Quick Quality - allows you to select elements for mesh quality enhancement then select desired parameters as shown below:

• Fast Shell Enhancing attempts to fix failed elements only. Once they pass all selected criteria, no further enhancement is attempted.

• Slow Shell Enhancing attempts to fix failed elements and also to further improve all selected elements.

• All passes except Warp Enhancing will maintain nodes on the FE-Surface.

Warp Enhancing will move the node (within the specified tolerance) normal to the surface to decrease the warping.

303Loads and Boundary Conditions

Loads and Boundary Conditions

Loads and Boundary Conditions304

Loads and Boundary ConditionsThis chapter describes the loads and boundary conditions available when performing analysis with the SimXpert crash workspace. Each of the load types discussed may be applied to your model individually, or in any combination.

Supported Load and Constraint TypesMost often, boundary conditions are imposed in the form of constraints on selected degrees of freedom on the model. Typically, several degrees of freedom are constrained to ground, using Single Point Constraints (SPC) boundary conditions.

Besides single-point constraints, crash workspace provides a method of creating linear constraint relationships between several degrees of freedom.

A third type of boundary conditions is the contact boundary condition for specifying that certain regions of the structure might be touching or separating during the simulation process. Contact boundary condition is an important feature of the crash workspace.

This section discusses the single-point and multiple-point constraints. The rigid elements are discussed under Meshing, and the Contact is discussed under the section on contact.

Single-Point Constraints

A Single-Point Constraint (SPC) is a constraint that is applied to a single degree of freedom, which may be either a component of motion at a node or the displacement of a scalar point.

The primary applications for single-point constraints are:

1. To tie a structure to ground.

2. To apply symmetric or anti symmetric boundary conditions by restraining the degrees of freedom that must have a zero value to satisfy symmetry or anti symmetry. Symmetry is discussed in the Modeling Guide.

3. To remove degrees of freedom that are not used in the structural analysis (that is, are not connected to any structural elements or otherwise joined to the structure).

SPC BC• *BOUNDARY_SPC constraints usually specified at model boundaries to define rigid support

points. These can also be used to apply an enforced nonzero displacement. Directions are in the applicable nodal coordinate system.

305Loads and Boundary ConditionsLoads and Boundary Conditions

• *CONSTRAINED_LINEAR_OPTION defines linear constraint equation between displacements and rotations defined in global (OPTION =GLOBAL), or local (OPTION =LOCAL) coordinate system. The constraint equation is generally of the form:

where uk are the displacements/rotations, and Ck are the user defined coefficients.

Nodal BC• FORCE and MOMENT -- Concentrated forces and moments, which are applied directly to

nodes. The magnitude is entered directly. The direction is defined by selecting an appropriate degree-of-freedom (DOF) code. The node or nodes to which forces or moments are to be applied, can be selected directly or via node set. Follower forces and moments can also be applied. The temporal variation of the force or moment can be defined by using a load versus time curve (LCID).

• Boundary Sliding Plane -- Boundary conditions at nodes on symmetry planes defined by creating the symmetry plane.

• Boundary Temperature -- Temperature Boundary Conditions at nodes for thermal loading, or temperature dependent materials.

• Initial Temperature -- Defines initial nodal temperatures. These can be applied either directly to the nodes, or via node set.

• Initial Foam Reference Geometry -- Defines reference configuration for the geometry of the foam material for initialization of stresses in the foam.

• Boundary Prescribed Motion -- Defines imposed (nonzero) nodal motion (velocity, acceleration, or displacement) on nodes, node sets, or rigid bodies.

Element BC• Load Shell -- Distributed pressure load applied to shell or thick shell elements, or element set.

• Load Beam -- Distributed traction load along any local axis of beam elements or a set of beams.

• Initial Strain Shell -- Applies initial strains to shell elements.

• Initial Stress Shell -- Applies initial stresses to shell elements.

• Initial Stress Beam-- Applies initial stresses to beam elements.

• Initial Stress Solid -- Applies initial stresses to solid elements.

• Initial Volume Fraction -- Defines initial volume fraction for different materials in multi-material ALE, or in single material and void models.

• Initial Momentum -- Defines initial momentum for depositing in solid elements, to simulate impulse loading.

01

CuC k

n

kk =

=


Load Segment • Applies distributed pressure load over a triangular or quadrilateral segment defined by four

nodes, over each segment in a segment set.

Global BC• BOUNDARY_CYCLIC -- Defines nodes in boundary planes for cyclic symmetry

• BOUNDARY_PRESCRIBED_MOTION -- Defines imposed (nonzero) nodal motion (velocity, acceleration, or displacement) on nodes, node sets, or rigid bodies.

• CONSTRAINED_ADAPTIVITY -- Defines adaptive constraints to constrain nodes to the midpoint along edges of shell elements.

• CONSTRAINED_GENERALIZED_WELD_BUTT -- Defines butt welds. Weld failures include both plastic and brittle failures. Coincident nodes are permitted, provided local coordinates are defined.

• CONSTRAINED_EULER_IN_EULER -- Defines coupling between materials in two overlapping, and geometrically identical multi-materials Eulerian mesh sets. It also allows frictional contact between two or more Eulerian materials.

• CONSTRAINED_GLOBAL -- Defines a global boundary constraint plane

• CONSTRAINED_INTERPOLATION -- Defines an interpolation constraint whereby the motion of a single dependent node is interpolated from the motion of a set of independent nodes.

• CONSTRAINED_POINTS -- Defines constraint between two points with the specified coordinates connecting two shell elements at locations other than nodal points.

• CONSTRAINED_RIGID_BODIES -- Defines rigid body stoppers, to conveniently control the motion of rigid tooling in metal forming applications.

• CONSTRAINED_RIGID_BODY_STOPPERS -- Defines the merger of two rigid bodies

• CONSTRAINED_SHELL_TO_SOLID -- Defines a tie (constraint) between the edge of a shell and solid elements.

• CONSTRAINED_TIE_BREAK -- Defines a tie (constraint) between the edge of a shell and solid elements enabling local release as a function of plastic strain at the shell elements surrounding the interface nodes.

• CONSTRAINED_TIED_NODES_FAILURE -- Defines a tied (constrained) node set with failure based on plastic strains.

• CONSTRAINED_JOINT_STIFFNESS -- Defines translational and rotational joint stiffness. Options include FLEXION-TORSION, GENERALIZED, and, TRANSLATIONAL.

• INITIAL_DETONATION -- Defines points to initiate high explosive detonations in parts

• INITIAL_GAS_MIXTURE -- Defines initial temperature and density of different gas species in *MAT_GAS_MIXTURE for the simulation of gas mixtures.

• INITIAL_VELOCITY -- Defines initial nodal velocities using node set IDs.

• INITIAL_VEHICLE_KINEMATICS -- Defines initial kinematical information such as orientation, yaw, pitch, and roll axes for a vehicle.

307Loads and Boundary ConditionsLoads and Boundary Conditions

• INITIAL_VELOCITY_RIGID_BODY -- Defines the initial translational and rotational velocities at the center of gravity for a rigid body. This input overrides all other velocity input for the rigid body and the nodes which define the rigid body.

• INITIAL_VELOCITY_GENERATION -- Defines initial velocity for rotating and translating bodies.

• INITIAL_VOID -- Defines initial voided part set or part numbers.

• INITIAL_VOLUME_FRAC_GEOMETRY-- Defines initial volume fraction of different materials in multi-material ALE, or in single material and void models.

• Load Blast-- Defines an airblast function for the application of pressure loads due to explosives in conventional weapons.

• Load Body-- Defines body force loads due to prescribed base acceleration or angular velocity using global axes definition. This load applies to all nodes in the model unless a part subset is specified via the *LOAD_BODY_PARTS keyword.

• Load Body Generalized-- Defines body force loads due to prescribed base acceleration, or a prescribed angular velocity over a subset of the model. The subset is defined by using nodes.

• Load Body Parts-- Defines body force loads for nodes belonging to selected parts.

• Load Brode-- Defines brode function for application of pressure loads due to explosives.

• Load Density Depth -- Defines density versus depth for gravity loading for analyzing submerged and underground structures.

• Load Mask-- Defines distributed pressure load over a three dimensional shell part. The pressure is applied to a subset of elements that lie within a fixed global box and lie either outside or inside of a closed curve in space which is projected onto the surface.

• Load Rigid Body-- Defines concentrated nodal force to a rigid body. The force is applied at the center of mass, or a moment is applied around a global or local axis.

• Load SSA-- Defines a simple way of loading the structure to account for the effects of primary explosion and the subsequent bubble oscillations.

• Load SuperPlastic Form -- Defines loads for superplastic forming analysis.

• Load Thermal Constant-- Defines nodal temperatures that remains constant (during the duration of the analysis) or thermally loading a structure for structural analysis.

• Load Thermal Load Curve -- Defines uniform (throughout the model) nodal temperatures that can vary (in time) according to a load curve.

• Load Thermal Variable -- Defines nodal sets giving the temperature that varies during the duration of the analysis.

• Airbag - Defines an airbag or control volume, providing a way of defining the thermodynamic behavior of the gas flow into the airbag, and a reference configuration for the fully inflated bag. The available thermodynamic relationships include: Simple Pressure Volume, Simple Airbag Model, Adiabatic Gas Model, Wang Nefske, Wang Nefske Jetting, Wang Nefske Multiple Jetting, Load Curve, Linear Fluid, Hybrid, Hybrid Jetting, and Hybrid Chemkin.

• Airbag Interaction -- Defines two connected airbags which vent into each other.


• Airbag Reference Geometry -- Defines airbag reference geometry

LBC SetsLoads and boundary conditions can be grouped into sets. The applied loads can be applied independently or in combination.

To group your applied loads into load sets select Create LBC Set from the BC menu.

Supply a name for your LBC set, then select the desired loads and boundary conditions.

309Contact

Contact

Contact310

Contact

OverviewThe simulation of many physical problems requires the ability to model the contact phenomena. This includes analysis of interference fits, rubber seals, tires, crash, and manufacturing processes among others. The analysis of contact behavior is complex because of the requirement to accurately track the motion of multiple geometric bodies, and the motion due to the interaction of these bodies after contact occurs or breaks. This includes representing the friction between surfaces and heat transfer between the bodies if required. The numerical objective is to detect the motion of the bodies, apply a constraint to avoid penetration, and apply appropriate boundary conditions to simulate the frictional behavior and heat transfer. This section gives an overview of the methods used in the SimXpert crash Workspace for handling contact.

Contact problems can be classified as one of the following types of contact.

• Deformable-Deformable contact between single (self-contact), or multiple two- and three-dimensional deformable bodies.

• Rigid - Deformable contact between a deformable body and a rigid body, for two- or three-dimensional cases.

• Tied contact in two and three dimensions. This is a general capability for tying (bonding) two deformable bodies, or a deformable body and a rigid body, to each other.

Contact problems involve a variety of different geometric and kinematic situations. Some contact problems involve small relative sliding between the contacting surfaces, while others involve large sliding. Some contact problems involve contact over large areas, while others involve contact between discrete points. The approach adopted by SimXpert crash Workspace to model contact can be used to handle most contact problems.

Contact MethodologyThis section gives an overview of the methods used in the SimXpert crash Workspace for handling contact.

Constraint Method

One side of the contact interface is called the slave side, and the other is designated as the master side. Nodes lying in those surfaces are respectively referred to as the slave nodes and the master nodes. Constraints are imposed on the global equations by a transformation of the displacement components of the slave nodes along the contact interface. To keep the efficiency of the explicit time integration scheme, the mass is lumped to the extent that only the global degrees of freedom of each master node are lumped. Impact and release conditions are imposed to ensure the conservation of momentum.

If the mesh in the master surface zone is finer than the slave surface zone, master nodes can penetrate through the slave surface without resistance, and create incorrect solution, especially if the interface pressures are too high. Better choice of master and slave zoning would minimize such errors in some

311ContactContact

cases. However, in some modeling situations (e.g. modeling of airbags in automotive crash applications) good zoning in the initial configuration may be poor zoning later as the deformation progresses.

Penalty Method

The penalty method places normal interface springs between all penetrating nodes and the contact surface. Momentum is conserved exactly without the necessity of imposing impact and release conditions. Currently there are three formulations of the penalty algorithm.

Standard Penalty Formulation: In this formulation, the interface stiffness is chosen to be approximately of the same order of magnitude as the stiffness of the interface element normal to the interface. If interface pressures become large, unacceptable penetration may occur. The usual remedy of scaling up the penalty stiffness, and scaling down the time step size increase the cost of the simulation.

Soft Constraint Penalty Formulation: In this formulation, in addition to the master and slave contact stiffness, an additional stiffness (called the stability contact stiffness) which is based on the stability (Courant’s criterion) of the local system comprised of two masses (segments) connected by a spring is added. The stability contact stiffness kcs is calculated as:

kcs = 0.5. SOFSCL. m*. (1/(Δtc(t))

where, SOFSCL is the Soft Constraint Penalty Scale factor, m* is a function of the mass of the slave node and the master nodes, and Δtc is set to the initial solution time step.

Segment-based Penalty Formulation: This formulation uses a slave segment-master segment approach instead of the slave node-master segment approach. It is especially very efficient for airbag self-contact during inflation and complex contact conditions.

Accounting for Shell Thickness

Shell thickness effects as well as change in thicknesses are accounted for in the crash Workspace.

Contact Damping

Viscous contact damping can be added to all contact options including single surface contact. It allows to damp out oscillations normal to the contact surfaces during metal forming operations, and it also works effectively in removing high frequency noise in problems involving impact.

Friction

Friction in crash Workspace is based on a Coulomb formulation

See “LS-DYNA Theory Manual” for a complete description of the friction formulation.

Contact312

Tied Contact

Tied contact or tied interfaces provides a convenient way of modeling with dissimilar (non congruent) meshes across an interface. This can often decrease the amount of effort required to generate meshes since it eliminates the need to match nodes across common faces of parts.

Contact Types

Different types of contact may be defined in SimXpert crash. Some of the most common contact types are listed here. Refer to the “LS-DYNA Keyword User’s Manual” for a more complete and detailed description.

• Automatic Nodes to Surface

• Automatic Single Surface

• Automatic One way Surface to Surface

• Automatic Surface to Surface

• Nodes to Surface

• Surface to Surface

• Tied Nodes to Surface

313ContactContact

• Tied Shell Edge to Surface

• Tied Surface to Surface

• Airbag Single Surface

• Rigidwall Geometric Flat

• Rigidwall Geometric Cylinder

• Rigidwall Geometric Sphere

Contact Parameters

A list of the most common contact parameters are described here. Refer to the “LS-DYNA Keyword User’s Manual” for a more complete and detailed description.

Variable Description

FS Static coefficient of friction

FD Dynamic coefficient of friction

DC Exponential decay coefficient

VC Coefficient for viscous friction

VDC Viscous damping coefficient in percent critical

PENCHK Small penetration option in contact search.

BT Birth time of contact (contact surface becomes active at this time)

DT Death time of contact (contact surface is deactivated at this time)

SFS Scale factor on default slave penalty stiffness.

SFM Scale factor on default master penalty stiffness

SST Optional thickness for slave surface (overrides true thickness)

MST Optional thickness for master surface (overrides true thickness)

SFST Scale factor for slave thickness (scales true thickness)

SFMT Scale factor for master thickness (scales true thickness)

FSF Coulomb friction scale factor

vs.F Viscous friction scale factor

CF Thermal conductivity of fluid between the slide surfaces

FRAD Radiation factor between the slide surfaces

HTC Heat Transfer conductance for close gaps

GCRIT Critical gap. Use Heat Transfer conductance defined (HTC) for gap thickness less than the value of GCRIT

GMAX No thermal contact if gap is greater than GMAX

Contact314

CD_FAC A multiplier used on the element characteristic distance for the search algorithm.

SOFSCL Scale factor for constraint forces of soft constraint option

LCIDAB Load Curve Id defining thickness of airbag (used in airbag contacts)

MAXPAR Maximum parametric coordinate in segment search.

EDGE Edge to edge penetration check

DEPTH Option to search depth in automatic contact

BSORT Number of cycles between bucket sorts

FRCFRQ Number of cycles between contact force updates for penalty contact formulations

PENMAX Maximum penetration distance

THKOPT Thickness option

SHLTHK Shell thickness option

SNLOG Option to enable/disable shooting node logic in thickness offset contact

ISYMB Symmetric plane option (set to 1, to retain the correct boundary conditions in models with symmetry.)

I2D3D Segment searching option

SLDTHK Solid element thickness (a nonzero positive value activates the contact thickness offsets in the contact algorithm where offsets apply)

SLDSTF Solid element stiffness (a nonzero positive value overrides the bulk modulus taken from the material model referenced by the solid element)

IGAP Flag to improve implicit convergence behavior at the expense of creating some sticking, if parts attempt to separate

IGNORE Option to allow/ignore initial penetrations

trackpen Flag for initial penetration compensation

bucket Bucket sorting frequency

lcbucket Load Curve Id defining bucket sorting frequency vs. time

nseg2trac Number of segments to track for each slave node

initiator Number of iterations for initial penetration checking

Variable Description

315Simulation

Simulation

Time Step Control316

Time Step ControlDuring the solution a new time step is estimated by taking the minimum value over all the elements in the model:

where, N is the number of elements, and a is the scale factor.

For stability reasons the scale factor a is typically set to a value of 0.90 (default) or smaller.

Time Step for Solid Elements

A critical time step size, Δte, is computed for solid elements from:

where, c is the adiabatic speed of sound, Q is a function of the bulk viscosity coefficients C0 and C1.

For elastic materials with a constant bulk modulus c can be computed as:

where, E, ν, and ρ are respectively the Young’s modulus, Poisson’s ratio, and density.

where, Le is a characteristic length calculated as the minimum altitude (for 4-node tetrahedrons), or the

ratio of the element volume to the area of the largest face (for 8-node hexahedra)

Time Step for Shell Elements

For the shell elements, the time step size is given by:

{ }11 2 3min , , ,...,n

Nt a t t t t+Δ = ⋅ Δ Δ Δ Δ

( ){ }1/ 22 2

ee

Lt

Q Q cΔ =

+ +

( )( )( )

1

1 1 2

Ec

υυ υ ρ

−=

+ −

1 0 0

0 0e kk kk

kk

C c C L forQ

for

ε εε

+ <= ≥

se

Lt

cΔ =

317SimulationTime Step Control

where, Ls is the characteristic length, and c is the speed of sound:

Three user options exist for selecting the characteristic length Ls.

In the first (default) option, Ls is given by:

e

where, β = 0 for quadrilateral, and 1 for triangular shell elements, As is the area, and Li (i = 1, 2, 3, 4) is the length of the sides defining the shell elements.

In the second option, the following more conservative value is used for Ls:

where, Di (i = 1, 2) is the length of the diagonals.

The third option, which provides the largest time step size, and is often used for triangular shell elements with very small altitudes uses the following expression for Ls:

Time Step for Beam and Truss Elements

For the Hughes-Liu beam and truss elements, the time step size is given by:

( )21

Ec

ρ ν=

−

( )( )1 2 3 4

1

max( , , , 1 )s

s

AL

L L L L

ββ

+=

−

( )1 2

1

max( , )s

s

AL

D D

β+=

( ) 201 2 3 4

1 2 3 4

1max , min( , , , 10 )

max( , , , (1 ) )s

s

AL L L L L

L L L L

ββ

β+

= + −

e

Lt

cΔ =

Time Step Control318

where, L is the length of the element, an c is the speed of sound calculated as:

The Belytscho beam also uses smaller of the values given by:

and

where, I and A are the maximum value of the moment of inertia, and the area of the beam cross section respectively.

Time Step for Discrete Elements

For spring elements there is no wave propagation speed c to calculate the critical time step size.

However, based on the maximum eigenvalue of the spring with the nodal masses M1, M2 attached to the nodes connected to the spring, the critical time step size can be computed as:

Ec

ρ=

e

Lt

cΔ =

2 2

.5

3 13

12

e

Lt

c II AL AL

Δ = + +

( )1 2

1 2

22e

M Mt

k M MΔ =

+

319SimulationOutput Control

Output ControlThe Control and the database options are used to set solution and output options for the analysis.

Control320

ControlThe Control options are used to set solution options such as analysis duration (*CONTROL_TERMINATION), adaptive meshing (*CONTROL_ADAPTIVE), parallel processing (*CONTROL_PARALLEL), and output options such as energy (*CONTROL_ENERGY), output interval (*CONTROL_OUTPUT). Refer to the LS-DYNA Keyword user’s Manual for a complete list of the Control cards and options. These control options can be set, and or changed from the SimXpert crash Workspace. Many of these options have default settings which work pretty well in most situations. However, a set of standard or user selected control options can be imported from an existing LS-DYNA keyword file, for use either on an as-is basis, or to be selectively modified in the crash workspace GUI.

DatabaseThe LS-DYNA Database options define options for output files containing results information for post processing. For example, the use of the *DATABASE_BINARY_D3_PLOT card lets you select the time interval (DT) between output for the d3plot files. Refer to the “LS-DYNA Keyword User’s Manual” for a complete list of the database cards and options. These database options can be set, and or changed from the SimXpert crash Workspace. Many of these options have default settings which work pretty well in most situations. However, a set of standard or user selected control options can be imported from an existing LS-DYNA keyword file, for use either on an as-is basis, or to be selectively modified in the crash workspace GUI.

321SimulationPerform the Simulation

Perform the SimulationTo perform the analysis, export an LS-DYNA keyword file (File -> Export -> Dyna Model). This will create a keyword input file which can then be used to perform the simulation with LS-DYNA on a computer where it is installed.

Manually Invoking LS-DYNAAs a part of SimXpert Installation, the LS-DYNA Analysis Code solver is installed in a subdirectory under the main installation directory and can be invoked directly. Should you need to manually invoke LS-DYNA, run the executable found under the SimXpert installation directory.

To invoke LS-DYNA from Linux32:

<INSTALLROOT>/Nastran/md2009/dyna/linux32/run_dytran jid=jobid.key iam=simxcr

From Linux64:

<INSTALLROOT>/Nastran/md2009/dyna/linux64/run_dytran jid=jobid.key iam=simxcr

From Windows32:

<INSTALLROOT>/Nastran/md2009/dyna/win32/run_dytran jid=jobid.key iam=simxcr

From Windows64:

<INSTALLROOT>/Nastran/md2009/dyna/win64/run_dytran jid=jobid.key iam=simxcr

where jobid.key is a LSDYNA input deck.

For Linux32, the default INSTALLROOT Path for SimXpert R4 is /msc/SimXpert/R4

For Linux64, the default INSTALLROOT Path for SimXpert R4 is /msc/SimXpert_x64/R4

For Windows32/64, the default INSTALLROOT Path for SimXpert R4 is C:\MSC.Software\SimXpert\R4

Perform the Simulation322

323Example - Crushing of a Thin Square Tube

Example - Crushing of a Thin Square Tube

Crushing of a Thin Square Tube324

Crushing of a Thin Square TubeProblem Description

A square cross section thin tube is to be simulated for crushing by a rigid wall moving with an initial velocity toward one end of the tube, while the other end is fixed. The basic FEA model containing the nodes and the elements is imported from a Nastran input file. Complete the crush model with materials, sections, boundary conditions, loads, and analysis and output options for performing the crush simulation.

Some Key Data:

Cross-section of the tube: 69.954 mm X 69.954 mm

Length of the tube: 320 mm

Thickness of the tube: 1.2 mm

Weight of the rigid wall: 0.4 ton

Initial velocity of the rigid wall: 5646 mm/sec

Steps:

Following are the steps to complete the crush model.

1. Launch SimXpert

Select Structures as the Workspace

2. Select the Solver Card as the GUI Options

Tools -> Options -> GUI Options

Select Solver Card

Click Apply

3. Set the Units for the model

Click Units Manager

Click Standard Units

Select mm, t, s as the units for Length, Mass, and Time respectively

Click OK

Click OK

325Example - Crushing of a Thin Square TubeCrushing of a Thin Square Tube

4. Import the FEA mesh from a MSC.Nastran input file

File -> Input -> Nastran ...

Select the file, square_tube_nast.bdf

Hint: You can find the above file in the PartFiles folder under the help folder in the SimXpert installation directory.

Click Open

Close the (pop-up) Notepad window (nastran.err - Notepad)

The imported FEA mesh represents a quarter model of the thin square tube.

Figure 1 Quarter model of a square section tube

5. Switch the workspace to crash:

Set workspace to crash

6. Create the material:

Materials and Properties-> MAT [1 to 20] -> [003]MAT_PLASTIC_KINEMATIC

Enter steel as the Title for the material

Enter value for RO: 7.85E-9


Enter value for E: 1.994E5

Enter value for PR: 0.30

Enter value for SIGY: 3.366E2

Enter value for ETAN: 1

Enter value for BETA: 1

Click OK

7. Create properties for the shell elements:

Materials and Properties-> Section -> SECTION_SHELL

Select 2 for ELFORM

Enter value for SHRF: 1.

Enter value for NIP: 3

Note: Hit the Enter key, after typing 3 for NIP. Otherwise, the change will not be made.

Enter value for T1: 1.2




Click OK

8. Assign property and material to the part:

Right click on the (part) PSHELL... in the Model Browser

Click Properties on the pop-up window

Double click on the SECID data box, and click Select

Select SECTION_SHELL_1 from the Select a PSECTION form

Click OK

Double click on the cell below MID, and click Select

Select steel from the Select a Material form

Click OK

Set the value for ADPOPT to 1

Click Modify

Click Exit

9. Create the boundary conditions for the tube:


LBCs -> LBC -> SPC -> Boundary SPC

Make sure all six DOFs are checked-in (selected)

Click Store

Click Exit

Pick all the nodes on the bottom of the tube

Click Done on the Pick panel

This fixes the bottom edge of the tube against all translations and rotations.


Figure 2 Boundary conditions for the tube model

Top edge

Bottom edge (fixed)

z-symmetry edge

x-symmetryedge



Check in DOFX, DOFRY, DOFRZ

Click Store

Click Exit

Pick all the nodes on the x-symmetry edge, except the node on the bottom edge.


This imposes the symmetric boundary condition on the x-symmetry edge.


Check in DOFZ, DOFRX, DOFRY

Click Store

Click Exit

Pick all the nodes on the z-symmetry edge, except the node on the bottom edge.


This imposes the symmetric boundary condition on the z-symmetry edge.

10. Create a constrained node set on all the nodes on the top edge:

Nodes/Elements ->Elements -> Create -> Rigid -> Constrained Node Set

Set DOF to 2

Click Store

Click Exit

Pick all the nodes on the top edge


11. Create mass elements to represent the rigid wall:

Elements -> Create -> 1 Noded -> Element Mass

Enter value for MASS: 0.01

Click Store

Click Exit

Pick all the nodes on the top edge, except two nodes where the symmetry edges meet the top edge.



Elements -> Create -> 1 Noded -> Element Mass

Enter value for MASS: 0.005

Click Store

Click Exit

Pick the two nodes where the symmetry edges meet the top edge


12. Create the initial velocity on the top nodes:

LBCs -> LBC -> Nodal BC-> Initial Velocity

Enter value for VY: -5646

Click on Define App Region

Pick all the nodes on the top edge

Click Create

13. Create an auto single surface contact:

LBCs -> Contact-> Automatic -> Auto Single Surface

Click OK on the Auto Single Surface form

14. Select the dyna control options:

Parameters -> Control -> [A to C] -> CONTROL ADAPTIVE

Enter value for ADPFREQ: 1.E-4

Enter value for ADPTOL: 5

Select value for ADPOPT: 2

Enter value for MAXLVL: 2

Enter value for ADPSIZE: 0

Click OK

Control -> [N to Z] -> CONTROL TERMINATION

Enter value for ENDTIME: 3.E-3

Click OK

Control -> [D to H] -> CONTROL ENERGY

Select value for HGEN: 2

Select value for RWEN: 2

Select value for SLNTEN: 2

Select value for RYLEN: 1


Click OK

Control -> [N to Z] -> CONTROL OUTPUT

Select value for NPOPT: 1

Select value for NEECHO: 3

Click OK

Control -> Title ->TITLE

Enter value for Title: Crushing of a thin square tube

Click OK

15. Select the dyna database options:

Database -> OPC -> DATABASE BINARY option

Enter valuEnter value for DT_D3PLOT: 1.E-4

Check in the IOPT select box, and set its value to 1

Click OK

Database -> OPC -> DATABASE option

Enter value for DT_GLSTAT: 2.E-5

Enter value for DT_MATSUM: 2.E-5

Click OK

16. Save the SimXpert database:

File -> Save As

Enter name for the file: square_tube_crush

Click Save

17. Run the Simulation:

Rght-click on Simulations

Enter name for Fle name: square_tube_crush

Click Save

18. Exit from SimXpert:

File -> Exit

19. Post-process the Results in ls-prepost


Figure 3 Von Mises Stress at Time = 0.003

Documents

SimXpert R3.2 Crash Workspace Guide