This comes up a lot. FEA cannot interpret stress at a sharp interior corner, because the correct stress is proportional to 1/r^n. I don't really kow what n is, it depends on other geometry. In your model, r is zero, so, the solution converges to infinity. The good news is, there is always some non-zero radius, even the corner of an end mill has a radius of around .0002in. The bad news is, the actual radius may be impractically small to model, like .0002 in. In your case, the effective radius has to do with the weld leg, I'm guessing.
- Some solutions are
- Modelling the welds--remember, the welds don't go under the stiffeners, only around them.
- Ignoring the local stress and looking at deformation--this requires some intuition about what is acceptable.
- Verifying the stress is not real by using mesh controls to make the mesh around the stress very small. You can trust stress values that converge, i.e., stop getting bigger as the mesh gets smaller. you can effectively drie the stress into the corner and ignore it, as you see that the convergent stress very close to the corner is acceptable.
There is a lot more to this, but you can google it if you want a more detailed explanation.
Serhey, check the forum. There have been a lot of discussions about this. Use the search parameter concentration or singularity. This is a topic we discuss with our customers in our mentoring service but this is also covered in the standard simulation training class.
Thank you gentelmen, I will dig more about it
Have a nice time