Tangent Modulus for PLA

[Aqib_]

Hi everyone,
I am trying to use bilinear isotropic properties for PLA in ansys for a model. I want to know tangent modulus value for PLA that can be used in Ansys. I dont know how to get the tangent modulus value. Is there anyone who can help me in this regard? As the stress-strain curve of PLA is downward in plastic region, even if I take a slope value from any point in plastic region, its negative and I can not use negative value in Ansys, it shows a yellow error. I am really stuck with this problem and can not proceed further. Any kind of advice is welcome. I really need it.

Thank you
Kind Regards
Aqib

 

[rickfischer51]

Estimate the maximum strain you will see. Then use a zero tangent modulus, and pick your yield point so the area under the BISO curve is the same as the area under the stress-strain curve up to that maximum strain estimate. Thats about the best you can do with BISO.

Rick Fischer
Principal Engineer
Argonne National Laboratory