*DAMAGE INITIATION

Specify material and contact properties to define the initiation of damage.

This option is used to provide material properties that define the initiation of damage. It can also be used in conjunction with the SURFACE INTERACTION option to define a contact property model that allows definition of damage initiation for cohesive surfaces.

This page discusses:

See Also
In Other Guides
Damage Initiation for Ductile Metals
Damage Initiation for Fiber-Reinforced Composites
Damage Initiation for Ductile Materials in Low-Cycle Fatigue
Defining the Constitutive Response of Cohesive Elements Using a Traction-Separation Description
Modeling Discontinuities as an Enriched Feature Using the Extended Finite Element Method
Contact Cohesive Behavior
UDMGINI

ProductsAbaqus/StandardAbaqus/Explicit

TypeModel data

LevelModel

Defining damage initiation as a material property

Required parameters

CRITERION

Set CRITERION=DUCTILE to specify a damage initiation criterion based on the ductile failure strain.

Set CRITERION=FLD to specify a damage initiation criterion based on a forming limit diagram.

Set CRITERION=FLSD to specify a damage initiation criterion based on a forming limit stress diagram.

Set CRITERION=HASHIN to specify damage initiation criteria based on the Hashin analysis.

Set CRITERION=HC to specify the Hosford-Coulomb damage initiation criterion.

Set CRITERION=HYSTERESIS ENERGY to specify damage initiation criteria based on the inelastic hysteresis energy density dissipated per stabilized cycle in a low-cycle fatigue analysis.

Set CRITERION=JOHNSON COOK to specify a damage initiation criterion based on the Johnson-Cook failure strain.

Set CRITERION=LARC05 to specify a damage initiation criterion based on the LaRC05 criterion.

Set CRITERION=MAXE to specify a damage initiation criterion based on the maximum nominal strain for cohesive elements or enriched elements.

Set CRITERION=MAXS to specify a damage initiation criterion based on the maximum nominal stress criterion for cohesive elements or enriched elements.

Set CRITERION=MAXPE to specify a damage initiation criterion based on the maximum principal strain for enriched elements.

Set CRITERION=MAXPS to specify a damage initiation criterion based on the maximum principal stress criterion for enriched elements.

Set CRITERION=MK to specify a damage initiation criterion based on a Marciniak-Kuczynski analysis.

Set CRITERION=MSFLD to specify a damage initiation criterion based on the Müschenborn and Sonne forming limit diagram.

Set CRITERION=PLY FABRIC to specify a damage initiation criterion for a bidirectional fabric-reinforced material.

Set CRITERION=QUADE to specify a damage initiation based on the quadratic separation-interaction criterion for cohesive elements or enriched elements.

Set CRITERION=QUADS to specify a damage initiation based on the quadratic traction-interaction criterion for cohesive elements or enriched elements.

Set CRITERION=SHEAR to specify a damage initiation criterion based on the shear failure strain.

Set CRITERION=USER to specify a user-defined damage initiation criterion for enriched elements.

Optional parameters

ALPHA

This parameter can be used only in conjunction with CRITERION=HASHIN.

Set this parameter equal to the value of the coefficient that will multiply the shear contribution to the Hashin's fiber initiation criterion. The default value is α=0.0.

ACCUMULATION POWER
This parameter can be used only with CRITERION=DUCTILE, CRITERION=HC, CRITERION=SHEAR, and, in Abaqus/Explicit, with CRITERION=JOHNSON COOK.

Set this parameter equal to the value of the power coefficient, N .

ANGLEMAX

This parameter is relevant only for CRITERION=MAXPE, CRITERION=MAXPS, or CRITERION=USER in enriched elements.

Set this parameter equal to the maximum allowed change in the crack propagation angle (in degrees) between the new crack propagation direction and the previous crack propagation direction. The default is 85°.

ANGSMOOTH

This parameter can be used only in conjunction with POSITION=NONLOCAL in enriched elements.

Set this parameter equal to the maximum allowed difference (in degrees) below which the normals of the crack facets are included in the moving least-squares approximation to smooth out the crack normals to obtain the crack propagation direction along the crack front. The default is 70°.

DEFINITION

This parameter can be used only in conjunction with CRITERION=MSFLD.

Set DEFINITION=MSFLD (default) to specify the MSFLD damage initiation criterion by providing the limit equivalent plastic strain as a tabular function of α .

Set DEFINITION=FLD to specify the MSFLD damage initiation criterion by providing the limit major strain as a tabular function of minor strain.

DEPENDENCIES

Set this parameter equal to the number of field variables included in the definition of the damage initiation properties. If this parameter is omitted, it is assumed that the damage initiation properties are constant or depend only on temperature. This parameter cannot be used with CRITERION=JOHNSON COOK.

FAILURE MECHANISMS

This parameter can be used only in conjunction with CRITERION=USER.

Set this parameter equal to the total number of failure mechanisms to be specified in a user-defined damage initiation criterion. This parameter value must be a nonzero.

FEQ

This parameter can be used only in conjunction with CRITERION=MK.

Set this parameter equal to the critical value of the deformation severity index for equivalent plastic strains, fe⁢qcrit. The default value is fe⁢qcrit=10.

Set this parameter equal to zero if the deformation severity factor for equivalent plastic strains should not be considered for the evaluation of the Marciniak-Kuczynski criterion.

FNN

This parameter can be used only in conjunction with CRITERION=MK.

Set this parameter equal to the critical value of the deformation severity index for strains normal to the groove direction, fn⁢ncrit. The default value is fn⁢ncrit=10.

Set this parameter equal to zero if the deformation severity factor for strains normal to the groove should not be considered for the evaluation of the Marciniak-Kuczynski criterion.

FNT

This parameter can be used only in conjunction with CRITERION=MK.

Set this parameter equal to the critical value of the deformation severity index for shear strains, fn⁢tcrit. The default value is fn⁢tcrit=10.

Set this parameter equal to zero if the deformation severity factor for shear strains should not be considered for the evaluation of the Marciniak-Kuczynski criterion.

FREQUENCY

This parameter can be used only in conjunction with CRITERION=MK.

Set this parameter equal to the frequency, in increments, at which the Marciniak-Kuczynski analysis is going to be performed. By default, the M-K analysis is performed every increment; that is, FREQUENCY=1.

GROWTH TOLERANCE

This parameter can be used only in conjunction with CRITERION=MAXPE, CRITERION=MAXPS, CRITERION=MAXE, CRITERION=MAXS, CRITERION=QUADE, CRITERION=QUADS, or CRITERION=USER for enriched elements in Abaqus/Standard.

Include this parameter to define a separate tolerance used for crack growth.

Set this parameter equal to the tolerance within which the damage initiation criterion in enriched elements with an existing crack must be satisfied. If this parameter is included but no value is specified, the value is set by the TOLERANCE parameter.

INISMOOTH

This parameter can be used only in conjunction with POSITION=NONLOCAL in enriched elements.

Set INISMOOTH=YES (default) to indicate the normals of pre-existing crack facets in elements are included in the moving least-squares approximation to smooth out the crack normals to obtain the crack propagation direction along the crack front.

Set INISMOOTH=NO to indicate the normals of pre-existing crack facets in elements are excluded from the moving least-squares approximation to smooth out the crack normals to obtain the crack propagation direction along the crack front.

KS

This parameter can be used only in conjunction with CRITERION=SHEAR.

Set this parameter equal to the value of ks. The default value is ks=0.

LODE DEPENDENT

Include this parameter to define a ductile damage initiation criterion that depends on the Lode angle.

NORMAL DIRECTION

This parameter can be used only in conjunction with CRITERION=MAXE, CRITERION=MAXS, CRITERION=QUADE, or CRITERION=QUADS for enriched elements in Abaqus/Standard.

Set NORMAL DIRECTION=1 (default) to specify that a new crack orthogonal to the element local 1-direction will be introduced when the damage initiation criterion is satisfied.

Set NORMAL DIRECTION=2 to specify that a new crack orthogonal to the element local 2-direction will be introduced when the damage initiation criterion is satisfied.

NPOLY

This parameter can be used only in conjunction with POSITION=NONLOCAL in enriched elements.

This parameter is used to specify the number of terms in the polynomial used for the moving least-squares approximation to smooth out the crack normals.

Set NPOLY=4 to use a linear polynomial approximation.

Set NPOLY=7 (default) to use a quadratic polynomial approximation.

Set NPOLY=10 to use a cubic polynomial approximation.

Set NPOLY=0 to suppress the moving least-squares approximation.

NUMBER IMPERFECTIONS

This parameter can be used only in conjunction with CRITERION=MK.

Set this parameter equal to the number of imperfections to be considered for the evaluation of the Marciniak-Kuczynski analysis. These imperfections are assumed to be equally spaced in the angular direction. By default, four imperfections are used.

OMEGA

This parameter can be used only in conjunction with CRITERION=MSFLD in Abaqus/Explicit.

Set this parameter equal to the factor ω used for filtering the ratio of principal strain rates used for the evaluation of the MSFLD damage initiation criterion. The default value is ω=1.0.

PEINC

This parameter can be used only in conjunction with CRITERION=MSFLD in Abaqus/Explicit.

Set this parameter equal to the accumulated increment in equivalent plastic strain used to trigger the evaluation of the MSFLD damage initiation criterion. The default value is 0.002 (0.2 %).

POSITION

This parameter can be used only in conjunction with CRITERION=MAXPE, CRITERION=MAXPS, CRITERION=MAXE, CRITERION=MAXS, CRITERION=QUADE, CRITERION=QUADS, or CRITERION=USER for enriched elements in Abaqus/Standard.

Set POSITION=CENTROID (default) to use the stress/strain at the element centroid ahead of the crack tip to determine if the damage initiation criterion is satisfied and to determine the crack propagation direction (if needed).

Set POSITION=COMBINED to use the stress/strain extrapolated to the crack tip to determine if the damage initiation criterion is satisfied and to use the stress/strain at the element centroid to determine the crack propagation direction (if needed).

Set POSITION=CRACKTIP to use the stress/strain extrapolated to the crack tip to determine if the damage initiation criterion is satisfied and to determine the crack propagation direction (if needed).

Set POSITION=NONLOCAL to use the stress/strain extrapolated to the crack tip to determine if the damage initiation criterion is satisfied and to use the stress/strain averaged over a group of elements around the crack tip in the enriched region to determine the crack propagation direction (if needed). By default, a moving least-squares approximation by polynomials is used to further smooth out the normals of the individual crack facets in elements that satisfy the damage initiation criterion to obtain the crack propagation direction along the crack front. Set NPOLY=0 to suppress this behavior. This option can be used only in conjunction with CRITERION=MAXPE or CRITERION=MAXPS.

PROPERTIES

This parameter can be used only in conjunction with CRITERION=USER.

Set this parameter equal to the number of material constants being specified for a user-defined damage initiation criterion. The parameter value must be a nonzero value.

RATE DEPENDENT

This parameter can be used only in conjunction with CRITERION=MAXE, CRITERION=MAXS, CRITERION=QUADE, or CRITERION=QUADS for either cohesive elements with traction separation behavior or cohesive contact in Abaqus/Explicit.

Include this parameter to define the damage initiation criterion as a function of the effective rate of separation.

R CRACK DIRECTION

This parameter can be used only in conjunction with POSITION=NONLOCAL.

Set this parameter equal to the radius around the crack tip within which the elements are included for calculating the averaged stress/strain and for smoothing out the normals of the individual crack facets along the crack front used to obtain the crack propagation direction. The default value is three times the typical element characteristic length in the enriched region.

REF ENERGY

This parameter can be used only in conjunction with CRITERION=HYSTERESIS ENERGY.

Set this parameter equal to a reference value of the accumulated inelastic hysteresis energy density per cycle. The default is 1.0.

SMOOTHING

This parameter can be used only in conjunction with POSITION=NONLOCAL.

Set SMOOTHING=NONE (default) to use the stress/strain at the integration points directly for averaging.

Set SMOOTHING=NODAL to assemble the stress/strain to element nodes and then interpolate to the integration points for averaging.

TOLERANCE

This parameter can be used only in conjunction with CRITERION=MAXPE, CRITERION=MAXPS, CRITERION=MAXE, CRITERION=MAXS, CRITERION=QUADE, CRITERION=QUADS, or CRITERION=USER for enriched elements in Abaqus/Standard.

Set this parameter equal to the tolerance within which the damage initiation criterion must be satisfied. The default is 0.05.

UNSTABLE GROWTH TOLERANCE

This parameter can be used only in conjunction with CRITERION=MAXPE, CRITERION=MAXPS, CRITERION=MAXE, CRITERION=MAXS, CRITERION=QUADE, CRITERION=QUADS, or CRITERION=USER for enriched elements in Abaqus/Standard.

Include this parameter to define a separate tolerance used for unstable crack growth.

Set this parameter equal to the tolerance within which the damage initiation criterion in enriched elements with an existing crack must be satisfied for multiple elements to be allowed to crack without excessively cutting back the increment size in an unstable crack growth analysis. If this parameter is included but no value is specified, the default value is infinity.

WEIGHTING METHOD

This parameter can be used only in conjunction with POSITION=NONLOCAL.

Set WEIGHTING METHOD=UNIFORM (default) to average the stress/strain with a uniform weight function.

Set WEIGHTING METHOD=GAUSS to average the stress/strain with a Gaussian weight function.

Set WEIGHTING METHOD=CUBIC SPLINE to average the stress/strain with a cubic spline weight function.

Set WEIGHTING METHOD=USER to average the stress/strain with a user-defined weight function.

Data lines to specify damage initiation for CRITERION=DUCTILE without the LODE DEPENDENT parameter

First line

  1. Equivalent plastic strain at damage initiation.

  2. Stress triaxiality, (-p/q).

  3. Strain rate.

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the equivalent plastic strain at damage initiation as a function of triaxiality, strain rate, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=DUCTILE, LODE DEPENDENT

First line

  1. Equivalent plastic strain at damage initiation.

  2. Stress triaxiality, η=-p/q.

  3. Lode angle term, ξ=cos⁡(3⁢Θ).

  4. Strain rate.

  5. Temperature, if temperature dependent.

  6. First field variable.

  7. Second field variable.

  8. Third field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than three)

  1. Fourth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the equivalent plastic strain at damage initiation as a function of triaxiality, Lode angle, strain rate, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=FLD

First line

  1. Major principal strain at damage initiation.

  2. Minor principal strain.

  3. Temperature, if temperature dependent.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the major principal strain at damage initiation as a function of minor principal strain, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=FLSD

First line

  1. Major principal stress at damage initiation.

  2. Minor principal stress.

  3. Temperature, if temperature dependent.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the major principal stress at damage initiation as a function of minor principal stress, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=HASHIN

First line

  1. Longitudinal tensile strength of the lamina.

  2. Longitudinal compressive strength of the lamina.

  3. Transverse tensile strength of the lamina.

  4. Transverse compressive strength of the lamina.

  5. Longitudinal shear strength of the lamina.

  6. Transverse shear strength of the lamina.

  7. Temperature, if temperature dependent.

  8. First field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than one)

  1. Second field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the strengths on temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=HC

First line

  1. a .

  2. b .

  3. c .

  4. n .

  5. d .

  6. ε ˙ 0 .

  7. Temperature, if temperature dependent.

  8. First field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than one)

  1. Second field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=HYSTERESIS ENERGY

First line

  1. Material constant, c 1 . (Units of C Y C L E .)

  2. Material constant, c 2 .

  3. Temperature, if temperature dependent.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables per line.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of material constants on temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=JOHNSON COOK

First (and only) line

  1. Johnson-Cook failure parameter, d1.

  2. Johnson-Cook failure parameter, d2.

  3. Johnson-Cook failure parameter, d3.

  4. Johnson-Cook failure parameter, d4.

  5. Johnson-Cook failure parameter, d5.

  6. Melting temperature, θmelt.

  7. Transition temperature, θtransition.

  8. Reference strain rate, ε˙0.

Data lines to specify damage initiation for CRITERION=LARC05

First line

  1. Longitudinal tensile strength, X T .

  2. Longitudinal compressive strength, X C .

  3. Transverse tensile strength, Y T .

  4. Transverse compressive strength, Y C .

  5. In plane shear strength, S L .

  6. Fracture plane angle for pure compression, α 0 (default=53°).

  7. Misalignment angle at failure for pure compression, φ 0 .

  8. Transverse shear strength, S T .

Second line

  1. Longitudinal shear friction coefficient, η L .

  2. Transverse shear friction coefficient, η T .

  3. Temperature, if temperature dependent.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables per line.
Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the strengths on temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=MK

First line

  1. Groove size relative to nominal thickness of the section, f0.

  2. Angle (in degrees) with respect to the 1-direction of the local material orientation.

  3. Temperature, if temperature dependent.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the groove size as a function of angular distance, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=MSFLD, DEFINITION=MSFLD

First line

  1. Equivalent plastic strain at initiation of localized necking.

  2. Ratio of minor to major principal strains, α .

  3. Equivalent plastic strain rate.

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the equivalent plastic strain at damage initiation as a function of α , equivalent plastic strain rate, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=MSFLD, DEFINITION=FLD

First line

  1. Major principal strain at initiation of localized necking.

  2. Minor principal strain.

  3. Equivalent plastic strain rate.

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the major principal strain at damage initiation as a function of minor principal strain, equivalent plastic strain rate, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=QUADE or CRITERION=MAXE without the RATE DEPENDENT parameter

First line

  1. Nominal strain at damage initiation in a normal-only mode.

  2. Nominal strain at damage initiation in a shear-only mode that involves separation only along the first shear direction.

  3. Nominal strain at damage initiation in a shear-only mode that involves separation only along the second shear direction.

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum normal and shear tractions at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=QUADE, RATE DEPENDENT or CRITERION=MAXE, RATE DEPENDENT

First line

  1. Nominal strain at damage initiation in a normal-only mode.

  2. Nominal strain at damage initiation in a shear-only mode that involves separation only along the first shear direction.

  3. Nominal strain at damage initiation in a shear-only mode that involves separation only along the second shear direction.

  4. Effective rate of separation.

  5. Temperature, if temperature dependent.

  6. First field variable.

  7. Second field variable.

  8. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum normal and shear tractions at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=QUADS or CRITERION=MAXS without the RATE DEPENDENT parameter

First line

  1. Maximum nominal stress in the normal-only mode.

  2. Maximum nominal stress in the first shear direction (for a mode that involves separation only in this direction).

  3. Maximum nominal stress in the second shear direction (for a mode that involves separation only in this direction).

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum normal and shear tractions at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=QUADS, RATE DEPENDENT or CRITERION=MAXS, RATE DEPENDENT

First line

  1. Maximum nominal stress in the normal-only mode.

  2. Maximum nominal stress in the first shear direction (for a mode that involves separation only in this direction).

  3. Maximum nominal stress in the second shear direction (for a mode that involves separation only in this direction).

  4. Effective rate of separation.

  5. Temperature, if temperature dependent.

  6. First field variable.

  7. Second field variable.

  8. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum normal and shear tractions at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=MAXPE

First line

  1. Maximum principal strain at damage initiation.

  2. Temperature, if temperature dependent.

  3. First field variable.

  4. Second field variable.

  5. Etc., up to six field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than six)

  1. Seventh field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum principal strain at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=MAXPS

First line

  1. Maximum principal stress at damage initiation.

  2. Temperature, if temperature dependent.

  3. First field variable.

  4. Second field variable.

  5. Etc., up to six field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than six)

  1. Seventh field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum principal stress at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=PLY FABRIC

First line

  1. Tensile strength along fiber direction 1, X 1 + .

  2. Compressive strength along fiber direction 1, X 1 − .

  3. Tensile strength along fiber direction 2, X 2 + .

  4. Compressive strength along fiber direction 2, X 2 − .

  5. Shear strength, S .

  6. Temperature, if temperature dependent.

  7. First field variable.

  8. Second field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than two)

  1. Third field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the strengths on temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=SHEAR

First line

  1. Equivalent plastic strain at damage initiation.

  2. Shear stress ratio, θs=(q+ks⁢p)/τmax.

  3. Strain rate.

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the equivalent plastic strain at damage initiation as a function of the shear stress ratio, strain rate, temperature, and other predefined field variables.

Data lines to specify damage initiation for CRITERION=USER

First line

  1. Give the material constants, eight per line.

Repeat this data line as often as necessary to define all material constants.

Defining damage initiation as part of a contact property model

Required parameters

CRITERION

Set CRITERION=MAXS to specify a damage initiation criterion based on the maximum nominal stress criterion for cohesive surfaces.

Set CRITERION=MAXU to specify a damage initiation criterion based on the maximum separation criterion for cohesive surfaces.

Set CRITERION=QUADS to specify a damage initiation based on the quadratic traction-interaction criterion for cohesive surfaces.

Set CRITERION=QUADU to specify a damage initiation based on the quadratic separation-interaction criterion for cohesive surfaces.

Optional parameters

DEPENDENCIES

Set this parameter equal to the number of field variables included in the definition of the damage initiation properties. If this parameter is omitted, it is assumed that the damage initiation properties are constant or depend only on temperature.

Data lines to specify damage initiation for CRITERION=QUADU or CRITERION=MAXU

First line

  1. Separation at damage initiation in a normal-only mode.

  2. Separation at damage initiation in a shear-only mode that involves separation only along the first shear direction.

  3. Separation at damage initiation in a shear-only mode that involves separation only along the second shear direction.

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum normal and shear separations at damage initiation as a function of temperature and other predefined field variables.

Data lines to specify damage initiation for CRITERION=QUADS or CRITERION=MAXS

First line

  1. Maximum nominal stress in the normal-only mode.

  2. Maximum nominal stress in the first shear direction (for a mode that involves separation only in this direction).

  3. Maximum nominal stress in the second shear direction (for a mode that involves separation only in this direction).

  4. Temperature, if temperature dependent.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the maximum normal and shear tractions at damage initiation as a function of temperature and other predefined field variables.