Stress strain curve beyond yield point

[john84]

Hello,

I have a composite material, I want to obtain its stress strain curve beyond the elastic region, how do I do that?

Thanks.

 

[john84]

Do I have to use deformation plasticity for that?

 

[portliner]

You must use a material model involving the material sub-option *Plastic. The applied load should be large enough to take the stress/strains into the plastic region.

 

[john84]

Thanks Portliner for your comments. I am defining the equivalent stress and the plastic strain of one of the material (since the other material is brittle) under plasticity option. While postprocessing, since the model is 3D, the sum of reaction forces divided by the cross sectional area would give me stress, whereas the displacement divided by the original length would give me strain.
I am still not getting a curve beyond the yield point. Do I have to use any other option?

Thanks in Advance.

 

[portliner]

mmm.. try to apply a given displacement by usíng *Boundary in the *Step, Nlgeom. Use. the sub-option "Nlgeom" on the *Step, should not be needed but it does not hurt.

 

[portliner]

Example, stress in Pa, plastic strain(elastic part disregarded)
the strain is dimensionless!!

*Plastic
450E6, 0.00
500E6, 0.002
530E6, 0.01