Radial return extension for the numerical simulation of visco-plastic processes

This paper deals with unified elastoplastic and elastic-viscoplastic constitutive equations for metals at high temperature submitted to large deformations. We present here a newly developed time integration algorithm which is an extension to the viscoplastic range of the classical radial return algorithm for plasticity. The resulting implicit algorithm is both efficient and very inexpensive. Moreover, if there is no viscosity effect (rate-independent material) the presented algorithm degenerates exactly into the classical radial return algorithm for plasticity.