The fundamental physics of the deformation process in metals is controlled by crystal plasticity, a type of non-recoverable strain whose evolution depends on the deformation history of the material (as in all plastic processes), and the relative orientation of the applied load and the crystalline grains of the metal.
Sheet metal, having been rolled into sheet form, typically has a microstructure that is strongly influenced by the rolling operation, consisting of a characteristic orientation distribution for the grains. These grains interact with each other and with the applied forming loads to control the behavior of the material as a whole.
Our goal is to capture this structure-dependence with very high fidelity, and to be able to predict the material response from the structure.
The project involves close collaboration between model builders and implementers, and experimentalists. The major tools are, firstly, the OOF object-oriented finite element code, as a platform for the implementation of model microstructures and candidate behavioral rules, and secondly, the experimental facilities of the NIST Center for Automotive Lightweighting, for characterization of the response of experimental samples on multiple strain paths.