A Study of Hardening Behavior Based on a Finite-Deformation Gradient Crystal-Plasticity Model

TL;DR

This paper systematically analyzes a finite-deformation gradient crystal-plasticity model to predict diverse hardening behaviors, rate effects, and size-dependent responses in single crystals using numerical simulations.

Contribution

It introduces a detailed implementation of Gurtin's model in FEM and explores its ability to capture complex hardening and rate-dependent phenomena.

Findings

Gradient-strengthening contributes to isotropic hardening.

Plastic flow and GND accumulation vary with scale and loading.

Model successfully predicts Bauschinger-like responses.

Abstract

A systematic study on the different roles of the governing components of a well-defined finite-deformation gradient crystal-plasticity model proposed by (Gurtin, 2008b) is carried out, in order to visualize the capability of the model in the prediction of a wide range of hardening behaviors as well as rate-dependent, scale-variation and Bauschinger-like responses in a single crystal. A function of accumulation rates of dislocations is employed and viewed as a measure of formation of short-range interactions which impede dislocation movements within a crystal. The model is first represented in the reference configuration for the purpose of numerical implementation, and then implemented in the FEM software ABAQUS via a user-defined subroutine (UEL). Our simulation results reveal that the dissipative gradient-strengthening is also identified as a source of isotropic-hardening behavior, which represents the effect of cold work introduced by (Gurtin and Ohno, 2011). Moreover, plastic flows in predefined slip systems and expansion of accumulation of GNDs are distinctly observed in varying scales and under different loading conditions.