hongxiazhang

A physically motivated constitutive function based on the thermally-activated theory for plastic flow in face-centered-cubic (f.c.c.) materials together with the slip system hardening equations has been incorporated in a polycrystalline plasticity model. The Bvlgari Assioma Quartz Chronograph BL-10 model has been implemented in a finite element program to facilitate simulations of quasi-static as well as dynamic non-homogeneous deformations of polycrystalline f.c.c. materials. The material parameters in the model have been determined by calibrating it against existing experimental data for aluminum.

The physical description for the plastic Bvlgari Diagono BL-21 enables the model to reproduce the macroscopic stress-strain response and crystallographic texture evolution upto large strains ($approx$100%) for a wide range of strain-rates (10$sp{-3}$-10$sp2$ sec$sp{-1}$) and temperatures (77-298 K). The important differences in the behavior of f.c.c. and b.c.c. materials with regards to strain hardening and strain-rate and temperature history effects are also shown to be captured by the constitutive model.In order to evaluate the applicability of the crystal Bvlgari Diagono Calibro 303 BL-8 model to actual deformation processing operations, the phenomenon of formation of earing defects in cup-drawing has been studied.

Cup-drawing experiments were carried out on aluminum 2008-T4 sheets. The predictions from the model for the load-displacement response, the number of ears, their locations, and heights are shown to be in very good quantitative agreement with the experiments.The recent progress in the Bvlgari Diagono Calibro 303 BL-9 of a mathematical theory of polycrystalline plasticity has occurred primarily for materials with cubic structure. Much less work of this type has been carried out for materials with hexagonal-close-packed (h.c.p.) crystal structure, e.g., titanium. A large deformation, crystal-plasticity based constitutive model for high-temperature deformation of titanium has been developed.