Learning Forum

[Sumaya061]

For one of my model solving process I have gotten this force convergence graph attached as the 1st snapshot below till now. The analysis settings were as the 2nd snapshot below. As you can see from the force convergence graph initially the substep converged for less no of iteration and the force convergence was way below the force criterion line. But later on the substep convergence are occurring after way more no of iterations. And also the force convergence points are all over the place specially after the 1st bisection occurred.

[John Doyle]

Sometimes it helps to study the solver output txt file to get more information as to the reason for bisections. Perhaps a contact pair just changed status and that is effecting the load path. Also, from your force convergence graph, it looks like there is something else that the code is trying to resolve besides just force imbalance. I say this because the force residual is already below the criteria, but the code continues to iterate. The solver output text file will also help interpret what remains to be solved. It is not necessarily a bad convergence pattern unless a contact pair has failed or is inadequate to deal with the full load path. Sometimes it also helps to use results tracking (under Solution Information) to keep track of critical results (I.e. contact status or displacements) to confirm that you will eventually converge to a good solution.n