Tuesday, 12 October 2004 - 10:30 AM

This presentation is part of : Graduate Student Competition

Multi-scale Finite Element Simulation on nanoindentation of Single-Crystal Copper

Yang Liu1, M. Yoshino2, Samit Roy1, Bo Wang1, Hongbing Lu1, and Ranga Komanduri1. (1) Oklahoma State University, 218 Engineering North, Stillwater, OK 74078, (2) Tokyo Institute of Technology, Tokyo, Japan

Scaling laws governing the mechanical behavior of materials from atomistic (nano), to continuum (macro) via mesoplastic (micro) scales are very important for various industrial applications. In this paper, finite element analysis of the nanoindentation of single-crystal copper is reported using multiscale simulation technique encompassing meso-plasticity and elasticity. Meso-plasticity theory was employed to investigate the local nanoindentation region where the dislocations are formed and emitted and the orthotropic constitutive model was used in the remaining region of the model. Based on the finite deformation theory, the mesoplasticity theory was implemented in FEM using ABAQUS/Explicit because of its capability to capture the dynamic effects during material deformation. The coordinate transformation was considered between the local crystal coordinates and the global Cartesian frame for the formulation of the stress-strain relation in this subroutine. The co-rotational stress rate and the rate dependent power-law expression for the shear strain rate were employed. The nanoindentation tests were conducted on a single crystal copper in an MTS NanoXP indentation system. The computational results were compared with nanoindentation experimental load displacement curves and the mechanical behavior of crystalline structures was investigated. Reasonably good agreements were observed between the computational and experimental data for both loading and unloading portion of the load displacement curves. Hence the 3D explicit FEA algorithm using mesoplasticity theory was validated. The shear strain, which results from the dislocation motion, is concentrated directly underneath the indenter and the distribution presents the symmetric and asymmetric patterns depending on the orientation of the crystal.

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