Investigation of Preferred Orientations in Planar Polycrystals

More accurate manufacturing process models come from better understanding of texture evolution and preferred orientations. We investigate the texture evolution in the simplified physical framework of a planar polycrystal with two slip systems used by Prantil et al. (1993, J. Mech. Phys. Solids, 41(8), 1357-1382). In the planar polycrystal, the crystal orientations behave in a manner similar to that of a system of coupled oscillators represented by the Kuramoto model. The crystal plasticity finite element method (CPFEM) and the stochastic Taylor model (STM), a stochastic method for mean-field polycrystal plasticity, predict the development of a steady-state texture not shown when employing the Taylor hypothesis. From this analysis, the STM appears to be a useful homogenization method when using representative standard deviations.</p

Simulation of the Portevin-Le Chatelier effect using polycrystal plasticity

A polycrystal plasticity model is used to describe the Portevin-Le Chatelier effect in a velocity controlled tension test. An elastoviscoplastic constitutive model is developed. The resulting fully implicit procedure is introduced into both Taylor (material point) and finite element models. Statistical analysis of the stress drops collected through finite element simulation indicate power law distributions for continuous band propagation, consistent with experimental observations. No “artificial" gradient plasticity formulation is required since spatial gradients exist naturally due to grain incompatibilities