Abaqus Non-Linear Material Analysis

[jetmaker]

I am looking for some help in running a non-linear material model in ABAQUS. For some reason, my plastic constituative model does not seem to be working as the stresses I am getting far exceed what should be seen on the stress/strain relationship.

I am using Patran as the Pre-/Post-processor, and define all the model requirements within Patran.

The model is a simple problem, a tension specimen with a centrally located hole. Material properties are 2024-T3 aluminum, 0.063" thick. A pressure load of 40000 psi is applied to one edge, and the other edge is restrained.

I have an Elastic Constituative model defined, and also the Plastic Constituative model defined. For the Plastic model, I use a Misses/Hill yield criteria and an isotropic hardening rule. Plastic properties are defined in a material field and relate true plastic strain vs. true stress. This material field is referenced by the Plastic model.

If anyone has some suggestions on why I might not be getting this problem to work, please let me know.

Thank you,
jetmaker

 

[brad]

What kind of "error" do you mean, and where are you examining these values? Definitely, if one is using a plastic constitutive model, the plastic strain MUST be consistent with stress (at least for a monotonic loading). Note, however, that this value is calculated at the element integration points. If you are looking at extrapolated nodal values, it is entirely conceivable that the extrapolation algorithm is leading to errant results being displayed (i.e. the calculated result is correct, but you are looking at something other than the first-order calculation).

Please further explain what you are evaluating, what the values of concern are, and what software you use to post-process. With that, I could further assist (if this post doesn't sort it out).

Brad