Time Incerement Effect in Abaqus

Hi,

I have written a user material for Abaqus to simulate the behavior of trabecular bone in large strain compression. The model undergoes elastic and plastic deformation. In the plastic regime, hardening and damage are growing depending on cumulated plastic strain.

I realized that the convergence of the model dependens on the max. time increment, given in the input file. For instance, when I use 0.001 as the max deformation allowed in each time increment the simulation stops almost at the beginning; however, when I use a max. time increment greater or equal to 0.003 the simulation undergoes large deformation (around 80 %). I would be thankful if someone can shed some light and help me through it to understand why smaller time increment may sometimes stop the simulation like this at the beginning! While based on my knowledge to keep the convergence it would be better to have smaller increments.

Best regards,

Hadi