What is the basic difference between Deformation theory and flow theory of plasticity ?

Dear Suman,

                  This is what abaqus says.. Even I am not sure.. Refer abaqus theory manual for further details.

Deformation plasticity theory is provided in Abaqus/Standard to allow fully plastic analysis of ductile metals, usually under small-displacement conditions, for fracture mechanics applications. The model is based on the Ramberg-Osgood relationship. In this section the detailed constitutive model is defined. The procedure for obtaining fully plastic solutions generally consists of incremental loading until the response is fully plastic.

The model is termed deformation plasticity because the stress is defined by the total mechanical strain with no history dependence. There is no “unloading” criterion (to allow recovery of the initial elastic stiffness immediately after a strain reversal), so that the model is only useful as a plasticity model in cases of continuous flow. It is, in fact, a nonlinear elastic model; but at a limit state when all of a specimen or structure is responding plastically, this model is a useful equivalent representation of the plastic response because it has such a simple form.

Thanks and Regards,

Rohith