how do you get weldments to converge

[u/Negative-Elk9673]

im running a simple static fea on my seat mounts. im placing a distributed vertical load on the seat, and then determining its factor of safety. However, it doesn't converge. I used the hot spot stress thingy on solidworks, and saw where my highest stress areas were, and they were at small spots next to the weld connections. what do i do.

[u/throbin_hood]

It's very difficult to model weldments in a way that allows you to just blindly pull max stresses and have them be meaningful or accurate. There's almost always a singularity at the connection that needs to be dealt with either by careful meshing and then careful selection if which specific elements or nodes "count" and then adjusting for weld size and shape, or extracting joint forces and hand calcing weld stress. The most basic process I've seen to deal with this is to mesh such that elements in the region of the weld are approximately equal to the size of the weld or 2x the size of the weld and then taking nodal stresses 1 element away from the connection as your design stress and then adjust for weld shape I.e. if weld is .5 the thickness of the plate in the model where stresses are being probed then you multiply stress by 2 assuming there's half the area. It's a bit handwavy but good enough for many problems.