Why when the thickness increases a convergence failure occures?
I need an urgent help to wrap my simulation up as much as fast. The problem with my FE analysis is as following:
The steel bar (SOLID ELEMENT 186) with outer tube (SHELL ELEMENT) are used for this knee brace. Cyclic loading is applied in the tip of the cantilever beam. Nonlinear FE is assumed here. On the other hand, material and geometry NLs are considered.
- When the initial thickness of outer tube is 2 mm the convergence have done without any error. As illustrated below.
- If the thickness of outer tube increases to 4 mm or 6 mm etc, convergence failure occurs with high distorted element in the knee brace (inside bar/outside tube). The error with number of 99999 is pop up as well.
I did make more fine mesh for both tube and bar, decrease the initial loading step, change the normal stiffness 0.1-1, and changed the contact formulation between tube and bar. By the way a frictionless contact is used here. Unfortunately, I have still been faced with convergence failure. help me please.