Hello Altair, I am formulating a problem for my college project. In the problem there is plastic deformation for the energy absorption. I used Law 36 and provide curve for true stress and plastic strain. The problem is that how we define failure cr

Aviral Mishra

Hello Altair, I am formulating a problem for my college project. In the problem, there is plastic deformation for the energy absorption. I used Law 36 and provided a curve for true stress and plastic strain. In the problem, plastic deformation is desired to absorb the energy, so I am a little bit confused to identify the failure limit. Kindly help me out to understand the failure criteria in law 36 material model.

Guilherme_Brandao

Hello Aviral Mishra,

LAW36 incorporates built-in failure criteria with the following definitions:

-Epmax: Maximum plastic strain at which an element is deleted. Importantly, this criterion is applicable under any loading (tensile, compression, shear..)

In case of tension, damage criteria can be applied as follows:

-Et = Initiation of tensile damage, where the stress value is reduced by the factor:

E1 is the maximum principal strain.

-Em: End of tensile damage. The stress value is null, but the element is not deleted.

-Ef: Tensile failure strain value for element deletion.

For more detailed information, you can refer to Radioss Manual: /MAT/ LAW36

If you would like to introduce tri-axiality, one can use /FAIL/BIQUAD, /FAIL/TAB1 etc. You can refer to: Radioss Failure Models

I hope this helps.

Kind regards,

Guilherme.