I am studying a 2D model for ideal plastic case.I am confused why different element size gives different results,I know that more elements give better results but at least the results should be close.In my case I am interesting about PEEQ and for different meshes i have different results.Can anyone help?
You have to refine mesh until the results in a specific location converges i.e., does not change significantly (say no more than 2%).
Different mesh size will give different results. You have to do grit independence test for mesh optimization
Hello Spyros
Meshing in FEM has many tips. choosing correct element type is very important to reach good result. choosing element is different in every problem. as a
obviously, you should increase number of elements until the results be independent of mesh sizing (results converge to almost constant values)
close to critical areas ( for example about holes ), try to use finer mesh.
Regards
Depending on the model, if it is ideally plastic, it may happen that there is a plastification zone forming that consists only of a few elements. If you reduce the mesh size, this zone may shrink accordingly.
I agree with Martin Baeker but the problem may become even more serious. In plane strain (and axisymmetry) the problem becomes hyperbolic and slip-lines develop representing jump discontinuities of velocity and stress. This is best known for the fully plastic beam with 2 constant stresses (+/- yield stress). The slip- lines represent the vanishing elastic domain. This happens across a line (a point). Therefore, if the mesh size changes so does the solution because you smear the jump discontinuity over few elements.
Dear Spyros Asrva
Take a look to the following link, it will be helpful to understand how to choose a accurate mesh size.
Mesh Size Does Matter: FEA Errors from Mesh Sizes :
https://youtu.be/EDs7uqDRHDE
Best regard !!
This is due to refine mesh. when your mesh is very refine it will converge easily and will give high results
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