Learning Forum

[biomeriel]

Hello all,

Below i'm showing the Force and displacement convergence plots. I 'm running a 3D model with 1 force and 3 moments (in the x, y and z axis) and i set the force convergence minimum reference to 0.2 as i was struggling to solve and i read that this can help that.

[Erik Kostson]

Merielnn3D models thus using 3D elements like a solid186 or 185 element which are used for 3D models do not have rotational degrees of freedom in their formulation, hence no moments, and thus no moment convergence is applicable to these (so that is why we do not see anything).Shell elements like shell181 do have both translational and rotational and then we would have a moment convergence graph.nnHope this clarifies things.nnThank younnekostsonn

[biomeriel]

Hello Ekostson,I believe im using element solid187, quadratic tetrahedron. And does it not matter that i have moments applied?? that's really interesting thank you for the quick response!Also do you have any insight then into why my model hasn't solved yet when both graphs have been below the convergence criterion ??? Thank you ,nnMeriel n

[peteroznewman]

Meriel,nYour model is making good progress and you just have to wait longer for it to finish.nThis solution wasted time calculating 26 iterations before starting over with a smaller Initial Time Step.nIf you have to solve it again, you should set the Auto Time Stepping to On and set the Initial Substeps to 20. This will save some time over the one you show above.n

[Erik Kostson]

MerielnnYes, solid 187 tet elements are also 3D with translational dof only and no rotations/moments in their FE formulation (just like solid186 and 185), so it does not matter that we have moments applied to it, because they simply do not have rotation inbuilt in their FE formulation (they have translations and hence forces, so that is what we need to monitor for convergence).All the bestnnErik Kostsonn

[biomeriel]

Hi peter and Erik,Thank you very much for the insight and advice! i'm running a new model with the new knowledge nAll the very best, nMerielnn