Learning Forum

[Ji-Hyun Jeon]

I did a crash simulation in Explicit and saw the difference in results based on Failure properties. 

 

1. What is the difference in the physical properties of Tense pressure failure so that the crack seems to have progressed? 

 

2. Tense pressure failure is a physical property that is not applicable to the shell. Is it impossible to get a result of cracking the entire thin film in Shell?

[Chris Quan]

Explicit Dynamics system uses Autodyn solver. In Autodyn, stresses tensor is the sum of hydrostatic stress or volumetric stress plus deviatoric stress. 

Principal stress failure is calculated from the deviatoric stress tensor while tensile pressure failure is calculated from the hydrostatic stress tensor. 

Shell elements do not have volume. Thus hydrostatic stress is not available. That's why Tensile Pressure Failure is not available to shell elements.

If shell elements must be used, you may consider to add Stochasetic Failure to the Principal Stress Failure. Stochastic Failure will randomize the failure parameters from element to element. Each element could have different failure parameter (for example, maximum principal stress), with the 50% possibility on the nominal value defined in Principal Stress Failure. See the picture below.

This will help you to create more realistic crack pattern from simulations.  

 

 

[Ji-Hyun Jeon]

Hello.

Do I usually use the same value for the Stochastic Failure model?

Thank you for your resply.