Mesoscale Modeling of Failure in Partially Sintered Metals and Homogenization to Macroscale

In this paper, we present a methodology for the multiscale analysis of deformation and failure of partially sintered metals. This methodology is based on experimental investigations, mesoscale modeling with the finite element method (FEM), and transfer of relationships derived at the mesoscale to the macroscale using a homogenization process. It can be used to investigate structure-properties relationships and is illustrated for a specific type of copper. The material is produced from cold-pressed spherical powder sintered at 700° C. Based on the statistical analysis of micrographs, three-dimensional voxel-based representative volume elements were generated. From these RVE’s, finite element models were built. The material data for these mesoscopic models was derived partly from literature and partly from fitting simulated homogenized stress-strain response to experimental tensile tests. LS-Dyna’s node-split feature was used to model failure within the RVE. Using homogenized stress-strain relationships obtained from RVE simulations with different loading types, a macroscale material model which includes non-linear plastic hardening and the dependence of failure strain on stress triaxiality was derived. This model is used in a macroscopic compression simulation and compared with a corresponding experimental result. Finally, an application of the mesoscopic model for fragmentation analysis illustrates possible future applications.

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