While performing FEM analysis , I got the error that ''4 elements are distorted. Either the isoparametric angles are out of the suggested limits or the triangular or tetrahedral quality measure is bad. The elements have been identified in element set WarnElemDistorted.
Displacement increment for contact is too big.'' The mesh I was using was a tet mesh. So I want to know that how do I unmesh these 4 elements so that my model runs?? or is there any other way so that I can make my model run????
Generally, the excessive distortion occurs in elements which play an important role determination of the model response; so, their exclusion may not be considered as a priority. You may use another element shape e.g. hexahedral or the modified version of tetrahedral elements which the Abaqus Documentation recommends using. Also, finer meshes works in many cases. As another option, you may define a "very small" amount of artificial damping in the material of those elements; in dynamic explicit method, this also works well for this error.
If this is a one-time thing, an easy way to do this would be:
Find out which nodes you want to shift.
Use the Job manager to write an inp-file
Edit the node coordinates in the inp-file directly and run it from a command line.
Usually as long as distortion doesn't generate an error, the warning itself is not a problem. It is more likely that there is some issue with the contact you defined, than those 4 elements, so no need to delete them. Or if you want, you can comment out the element line from the .inp file, but I don't think that's a solution to the problem.
To improve contact convergence you can try the following:
-Switch to linear elements
-Turn on contact stabilization
-Use adjustment
-Change it to a tie and check if the model solves. It might be some other issue with the model that causes non-convergence.
I hope this helps,
Best regards,
David
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