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Dear Abaqus Users,
I'm running a simulation of the unloading process of a circular hole (=Tunnel excavation). I'm using linear elastic perfectly plastic material behavior and CPE8 Elements. The problem itself is perfectly axissymmetric. I investigated two different ways of unloading: (i) stepwise unloading with steps, where the load is held constant for a certain time and (ii) linear unloading. In case (ii) I get the expected axissymmetric results. In case (i) strange oscillations of the results occur around the circular hole.
In my opinion, the way of unloading shouldn't lead to unsymmetric results in my case. Although I observed that Abaqus has problems with "idle" steps. Has anyone observed similar problems with stepwise unloading? I'm very happy for every comment! Thanks in advance.