I have a structure made out of steel consisting of many thin rods and some of them are welded to each other. I conducted a simple FEA static structural analysis to determine if the structure would fail under the critical loading conditions or not. For simplicity of the analysis, I did not model the welds between the rods and treated the whole as a single structure (which means that the connection between the rods were sharp with no welds and no fillets whatsoever). While examining the results, it was observed that the structure overall was safe from undergoing any plastic failure but the sharp connections between the rod (which are supposed to be welded) were experiencing plastic failure.
Now my question is, what should I do? Should I just believe that the weld will be strong enough in reality so that we can safely ignore and disregard the stress accumulation at the rod connections, or should I be concerned of that highly stressed region and do some geometric modifications to overcome that apparent local plastic deformation?
P.S. : If I increase the thickness and external diameter then these stress concentrations decreases and the structure is no longer failing at these connections, but I could not tolerate more mass into my structure. Plus, in FEA results, it didn't come out as a singularity either according to my interpretation.