https://forums.autodesk.com/t5/robot-structural-analysis-forum/solver-for-non-linear-analysis/m-p/5568178#M66824 The reasons can be different.<BR />This is my assumption: in case of nonlinear buckling critical load is exceeded in this case. Thu, 02 Apr 2015 08:21:48 GMT Rafal.Gaweda 2015-04-02T08:21:48Z