Examine the state variable outputs from Helius PFA that are stored in the results file.
Unfortunately, the current release of Patran does not allow for viewing of cohesive state variables. It may be possible to view results of cohesive state variables with another post-processing tool.
Important state variables to consider when examining results from an analysis with cohesive user materials are SV2, SV3, and SV7.
- SV2 represents the damage state at each integration point in cohesive elements that use Helius PFA cohesive materials. This value is an integer between 0 and 26. A value of 0 means damage has not initiated and a value of 26 means damage has fully evolved at the integration point and its stiffness has been reduced to zero. Intermediate values, say a value of 10, mean that damage has initiated and the stiffness of the element has been partially reduced.
- SV3 represents the failure index at each integration point. It is a continuous variable that can have a value between 0 and 1. A value of 0 indicates there are no stresses (or only normal compressive stresses) at the integration point. A value of 1 indicates that the failure initiation criterion has been satisfied and the process of damage evolution (stiffness reduction) has begun at the integration point. Intermediate values, for example 0.50 mean that 50% of the failure initiation criterion has been satisfied.
- SV7 is referred to as the damage variable (D). SV7 is a continuous real variable between 0 and 1 that indicates how much damage has occurred at the integration point. A value of 0 corresponds to an undamaged integration point that has its original (full) stiffness. A value of 1 corresponds to a fully degraded (zero stiffness) integration point.
In summary, SV3 can be thought of as a 'pre-failure' measure of how close the integration point is to failure initiation and SV7 can be thought of as a 'post-failure' measure of how close the integration point is to complete stiffness reduction after failure initiation.
Please consult Appendix D of the User's Guide for further details on Helius PFA state variables for cohesive materials.