I'm fairly new to nonlinear simulations in solidworks. I'm trying to find the stresses (especially concentrations) on a steel shaft undergoing torsion. Using linear static studies was obviously incorrect because of the radial deformation of the coupling and shaft. I can't get the nonlinear simulation to completely solve and would appreciate any advice available. The error I keep giving either tells me to change te singularity elimination factor either up or down, which has not worked. As the simulation runs it keeps deciding that the current iteration step is too big and goes towards smaller and smaller iterations and eventually fails.

The warnings given are:

PCGLSS0204:Negative or zero pivot 4.474550e-011 at row 64865 

Max. allowable iterations is increased by 5 for this step:

Thanks for any help