problem with large strain simulation

[philets]

Dear all,

3D model --> solid186
nonlinearities : BISO and large strain

I have convergence trouble with a large strain simulation. During the simulation, Ansys tell me that "element xxx is turning inside out". I tray to change the mesh density,
reduce the load step, change the element type... but no good results. It is possible to remesh my volume during the simulation??? Somebody know someting to do?

tanks in advance

Philippe Theriault
eng. jr.
Ecole de technologie superieure

 

[corus]

I have seen the same thing in Abaqus. Elements turning inside out are due to excessive strains. The way Abaqus resolves the problem is to apply only a fraction of the load until a converged solution is obtained, and then to gradually increase the load up to the required value. If the reduction in load is too great then it eventually stops. This usually indicates a problem in the way you have loaded the model, or because you have a large stress concentration at a point.
If you are applying an ideal elastic-plastic curve then try making the plastic part of the slope have a slight upward slope rather than it being horizontal, that helps convergence.