Hi everybody,

have any one used so far the 2-layer non-unified viscoplasticity material model of Abaqus. if yes, I am trying to simulate a relaxation test: a specimen (1 cubic element) is compressed to a certain strain which is then fixed  for a certain amount of time (180 sec). During the fixation relaxation of the stress should occur. I expect in this model to have a stress relaxation in the elastic-viscous network, while the stress in the elastic-plastic  network should remain constant. Unfortunately, I am obtaining a relaxation in the elastic-plastic network, even though when no yielding has occured.

 Does this make sense? any opinions?

 regards

An intensive metal plasticity/viscoplasticity literature review is needed, with drawbacks and capabilities of different models. Any found previous work?