This project aims to improve models linking the microscale, grain-level deformation properties, and the macroscopic, continuum deformation properties. The motivating application is automotive lightweighting -- a better understanding of the forming process will allow manufacturers to minimize the time to implement a wider range of economical alternative materials. Ideally, we would like to be able to predict complex formation paths from the smallest practical set of easily-measured features of the input material. The expected benefits of high-quality forming models should extend to many other applications.
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.