Numerical modelling and localized failure analysis in metal powder forming processes

A general framework for the finite element simulation of powder forming processes is presented. The research is focused on two different operations: the compaction process of powder and the process of localization. In the process of compaction, powders exhibit strain or work hardening, the volume reduces and the material becomes harder. A model is adopted to represent this physical process by employing an updated Lagrangian formulation for large deformation, a hardening cap model for the compressible behaviour of powder material and an interface element formulation for frictional behaviour of the contact surface. An adaptive analysis based on error estimates and automatic remeshing techniques is also applied to simulate the compaction process. In the process of localization, the ultimate capacity of the new materials is evaluated using the analysis of failure. A method for dealing with incompressible material is presented for capturing the strain localization and displacement discontinuity. An adaptive procedure is also introduced for elongating elements with suitable error measures, which will indicate and capture effectively the localization regions.