element distorted under frictional contact

[totosay]

Hi, All:
I am trying to simulate a metal ball traped between two plates. Firstly I applied downward displacement on the upper plate and the ball started to deform. Then I applied a horizontal displacement (parralle to the contact surface) on the upper plate. Ansys reported the elents consisting the ball became highly distorted and the simulation was disconvergent. Could anybody tell me how to solve it? Thanks in advance!
Toto

 

[maxPE]

Contact is a serious analysis. I suggest that the problem lies either in the load application or that the elements are distorting beyond ansys's capability. If the latter is true you need to use a explicit analysis code for the solution as abaqus or use ansys's explicit code. If the former is the problem I would apply the load as a displacement of the top plate just to touch slightly the ball. (first load step) I would then remove the displacement load and apply a small pressure to the top plate. This pressure should be so small that the problem will converge easily. Next increase the pressure incrementally till you reach your final requireed load. If the problem diverges before you reach your goal it is likely that the element distortion is too great for standard ansys implicit formulation.