Damage Initiation

There are three rupture criteria used by Advanced Material Exchange. By default, the Polynomial Stress rupture criteria is used to predict the initiation of damage. Advanced Material Exchange stores the parameters associated with this criterion in the .sif file. The HIN file can be used to adjust the parameters of the Polynomial Stress rupture criterion, or to switch to the MCT or Maximum Effective Stress rupture criteria. The *DAMAGEINITIATION keyword must be preceded by a valid *MATERIAL or *ENVIRONMENT keyword.

*DAMAGEINITIATION, TYPE=[POLYSTRESS/MCT/MAXEFFSTRESS]

where TYPE=POLYSTRESS is used to modify the coefficients of the Polynomial Stress criterion, TYPE=MCT is used to switch to the MCT rupture criterion, and TYPE=MAXEFFSTRESS is used to switch to the Maximum Effective Stress rupture criterion.

TYPE=POLYSTRESS

If TYPE=POLYSTRESS is used, you have the ability to specify the coefficients A11, A22, A33, A12, A13, and A23 across a range of values for the first eigenvalue of the fiber orientation tensor. The range can span the possible values from 1.0 (perfectly aligned) to 0.333333 (3D random). Each unique set, or bin, of failure coefficients is defined using the *BIN keyword as a child of the *DAMAGEINITIATION keyword.

*DAMAGEINITIATION, TYPE=POLYSTRESS
*BIN, EIG1=EIGENVALUE
A11,A22,A33,A12,A13,A23

where EIGENVALUE identifies the first eigenvalue of the fiber orientation tensor associated with the set of failure coefficients defined on the data line. There is no limit to the number of *BIN keywords within each *DAMAGEINITIATION keyword. For example:

*DAMAGEINITIATION, TYPE=POLYSTRESS
*BIN, EIG1=1.0
A11,A22,A33,A12,A13,A23
*BIN, EIG1=0.99
A11,A22,A33,A12,A13,A23
*BIN, EIG1=0.985
A11,A22,A33,A12,A13,A23

...

*BIN, EIG1=0.362
A11,A22,A33,A12,A13,A23
*BIN, EIG1=0.341
A11,A22,A33,A12,A13,A23
*BIN, EIG1=0.333333
A11,A22,A33,A12,A13,A23

The failure coefficients defined on the data line will override the values stored in the .sif file. Each integration point in the model uses the nearest set of failure coefficients, based on the value of the largest eigenvalue of the fiber orientation tensor.

TYPE=MCT

If TYPE=MCT is used, you must specify the coefficients A1, A2, and A4 on the data line.

*DAMAGEINITIATION, TYPE=MCT
A1,A2,A4

TYPE=MAXEFFSTRESS

If TYPE=MAXEFFSTRESS, you must specify the maximum allowable effective stress on the data line.

*DAMAGEINITIATION, TYPE=MAXEFFSTRESS
maxeffstress

Consider the examples below which demonstrate the use of each option.

Polynomial Stress

*MATERIAL, NAME=CA-PLASTIC-1
*DAMAGEINITIATION, TYPE=POLYSTRESS
*BIN, EIG1=0.712
0.00084398, 0.000249862, 0.000249862, 0.000780995, 0.000780995, 0.000780995
*BIN, EIG1=0.7
0.000865139, 0.000251631, 0.000251631, 0.000770134, 0.000770134, 0.000770134
*BIN, EIG1=0.65
0.000312021, 0.000312021, 0.000312021, 0.00135684, 0.00135684, 0.00135684

MCT

*MATERIAL, NAME=CA-PLASTIC-1
*DAMAGEINITIATION, TYPE=MCT
0.0026, 0.0036, 0.0025

Maximum Effective Stress

*MATERIAL, NAME=CA-PLASTIC-1
*DAMAGEINITIATION, TYPE=MAXEFFSTRESS
150.0