Hardening parameters in law36 is not positive

Beginner93
Beginner93 Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

can anyone tell me if it´s possible to use a non monotonously rising curve for the material definition in a nonlinear static and implicit analysis with Radioss? The modell is built with solid elements (brick8) and m36 material definition.

I know with Optistruct it is not possible to use a falling curve. 

A picture of the curve is in the attachement.

 

Thanks a lot and greetings,

Luca

<?xml version="1.0" encoding="UTF-8"?>Curve.JPG

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Answers

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited December 2019

    Hi,

     

    the stress-strain slope should be positive (the data points must be in ascending order). Convert the engineering stress-strain to true stress-strain. The first point of yield stress functions (plastic strain vs stress) should have a plastic strain value of zero. The curve should be nearly flat (slightly increasing) after the ultimate strength. To model failure use εt,εm, and εf parameters or dedicated failure models. 

    <?xml version="1.0" encoding="UTF-8"?>s-s curve.jpg

    <?xml version="1.0" encoding="UTF-8"?>failure.jpg

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