Alternative approach in distortion gradient plasticity theory

This study presents an alternative thermodynamically consistent distortion gradient plasticity theory for polycrystalline materials. The formulation employs the principle of virtual power, laws of thermodynamics, and codirectionality hypothesis for the constructions of macroscopic and microscopic balance laws governing the elastic and plastic responses of the materials. Expressing the plastic distortion tensor in terms of accumulated plastic strain and plastic rotation vector shows that the two quantities are governed by independent plastic flow equations. In addition, it is obtained that the flow equation which governs the accumulated plastic strain interacts with the elastic response of the materials, while the flow equation governing the plastic rotation vector is independent of the elastic response. Finally and among other things, it is shown that the present model is computationally less expensive in the sense that it requires lesser numbers of equations for the prediction of plastic behavior of the materials.