Elastic - Plastic deformation in ABAQUS/CAE

[clarkea1]

Hi everyone,

I'm modelling what should be a relatively simple problem in ABAQUS/CAE - a 2d plane strain body with a pressure loading applied to one edge (representing hertzian contact). It works fine as an elastic problem, and gives results which are in very good agreement with the analytical solution to the problem. However, I'm interested in modelling plastic deformation due to the pressure loading. I've set the material to have elastic-perfectly-plastic properties, and again the job runs fine for loads which take the material only just above yield.

When I set the load to be higher (but the loads are still realistic real world loads), the solver hits problems. It gives messages like "the strain increment exceeded 50 times the strain for first yield", and "Didn't attempt the plasticity calculation for N nodes", and then fails as the solver tries to select increment times smaller than the default smallest increment.

I'm sure it's just a setting or two I've got wrong somewhere, but has anyone got any ideas? I'm quite new to this ABAQUS game, and my previous FEA experience has been limited to elastic modelling in Patran/Nastran, so any advice would be much appreciated.

Cheers

Alastair

 

[mrgoldthorpe]

You're using a dead load with a non-hardening material: sure to give problems once you start exceeding yield, particularly if plasticity is widespread rather than contained. Try using prescrbed displacement loading instead. You can get the nodal reactions (RFn) to see the loads applied. Otherwise, use the Riks solver with force loading.

 

[pilsung42]

Yes. I agree with mrgoldthorpe. Displacement-controlled type of loading is more stable for this particular problem.