A generalized plasticity model incorporating stress state, strain rate and temperature effects

Abstract

Due to the difficulties in decoupling of the strain rate and stress state effects at high strain rates, very few constitutive models can account for the both effects simultaneously. Based on a novel method in the determination of the shear behaviors and constitutive modeling of materials (J. Mech. Phys. Solids 129 (2019): 184–204)), this work aims to propose a plasticity model that considers not only the stress state effect, but also the effects of strain, strain rate, and temperature on the flow stress. A series of experimental work has been conducted on the Ti-6Al-4V alloy to determine its plastic behaviors and micromechanism under different stress states (uni-axial tension, compression, and simple shear) over a large range of temperatures (93 K–1073 K) and strain rates (10−3 s − 1–6.5 × 103 s−1). Then a stress triaxiality and Lode parameter dependent plasticity model is proposed to describe the experimental results, with its performance compared systematically with the Johnson-Cook (JC) model. A much higher accuracy is shown by the present model in the characterization of the tension and compression tests. The applicability of this model is also checked by implementing it in the commercial finite element program ABAQUS/Explicit via the user material subroutine coded as VUMAT. Compared to the JC model, an obvious improvement is observed for the present model in the simulation results of both the stress waves and the flow stress curves.