A virtual crystal plasticity simulation tool for micro-forming

Abstract

The trend of increasing miniaturization of varied products and devices with a wide range of applications necessitates the forming of metallic parts with dimensions at the micron scale. In micro-forming, the stress and deformation are highly anisotropic. Hence, conventional macro-mechanics models fail to capture the important features, such as necking and bending resulting from strain localization. In this paper, a virtual integrated micro-mechanics simulation tool is presented, that was developed within the framework of Crystal Plasticity (CP) theory. With this tool, a polycrystalline Finite Element (FE) model was produced by introducing grain size, orientations and distribution patterns using VGRAIN software. ABAQUS software was used and the CP constitutive equations were implemented through a user-defined material subroutine, VUMAT. Typical micro-forming processes simulated include tension, extrusion and hydro-forming to demonstrate the effectiveness of the integrated simulation system. Finally, a map is proposed that establishes bounds of appropriate usage for different modeling techniques, namely a macromechanics plasticity model and a micro-mechanics crystal plasticity model, which will be useful to engineers in the metal forming industry in choosing suitable simulation tools.