From Atoms to Autos - A new Design Paradigm Using Microstructure-Property Modeling Part 1: Monotonic Loading Conditions

A multiscale analysis was performed to develop a macroscale microstructure-mechanical property model that includes several types of microstructural inclusions found in an A356-T6 cast aluminum alloy for use in automotive chassis component design. This microstructureproperty model can be used for finite element analysis in which the deformation history, temperature dependence, and strain rate dependence vary. To capture the history effects from the boundary conditions and load histories, the microstructural defects and progression of damage from these defects and microstructural features such as casting porosity, silicon particles, and intermetallics must be reflected in the model. Internal state variables are used in the material model to reflect void/crack nucleation, void growth, and void coalescence from the casting microstructural features under different temperatures, strain rates, and deformation paths. Furthermore, internal state variables are used to reflect the dislocation density evolution that affects the work hardening rate and thus stress state under different temperatures and strain rates. In order to determine the pertinent effects of the microstructural features, several different length scale analyses were performed. Once the pertinent microstructural features were determined and included in the microstructure-mechanical property model, tests were performed on a control arm to validate its precision. Very encouraging results were demonstrated when using the model for optimizing structural components in a predictive fashion.