Force-penetration curve in indentation test simulation with ABAQUS CAE

Dear All,

I have the following problem. I simulate an indentation in two steps. At first step the indenter penetrate to the material. At the second step it withdraws from it. The problem, at the second step force simply drops. What could be the reason? Incorrect boundary conditions, very soft behaviour of material??? Specialists, please help.

Best regards

ABAgirl