Reply To: Why do the stresses increase near the supports?

[peteroznewman]

how can contact (like frictional, frictionless, rough) become a problem for convergence in my analysis? How to identify that the convergence problem is actually because of the contact and how to overcome it?nBelow is a link to a good blog on overcoming convergence difficulties involving contact. One good way to know that contact is causing the problem is to change the nonlinear contact to Bonded contact. If that solves, you have some indication that the problem is in the nonlinear contact.nhttps://www.padtinc.com/blog/overcoming-convergence-difficulties-in-ansys-workbench-mechanical-part-i-using-newton-raphson-residual-information/nAnd also, I am going to make a statement and would like to have your approval on this one.nThe magenta color line (in the Newton-Raphson Force convergence plot) represents the difference in the force vector between the applied force vector (for the global model) and the internal force vector (for all the nodes in the global model). This line need to have a value less than the teal line (which is basically a default value of 0.5% of the applied force vector) so that the system is considered to have converged (i.e. the equilibrium has been reached) and the solution then proceeds for the next time step''nYou have the right idea but are not using the correct terminology. Read this section of the Theory manual.nhttps://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v191/ans_thry/thy_tool10.htmlnThere are so many nodes in the global model (each having an internal force) and on top of that the external force is also a vector, however we just see a single value of the magenta line and teal line on the force convergence plot for a specific iteration of a certain time step; why is that?nBecause the solver needs a simple scalar summary metric to decide on the quality of the solution.nIs it possible if the magenta line starts below the teal line? Can it still cause any convergence difficulties?nYes, it's possible that the Force convergence starts below the teal line and it can still be a problem because of the other convergence metrics such as displacement.nWhy do we always observe the force convergence plot, although we have the availability of the displacement and moment convergence as well? Does all of them need to converge simultaneously in order to achieve an equilibrium within the system?nYes, all the convergence metrics have to converge to advance to the next load increment. Arrayn