Recent advances in computational and experimental capabilities have provided the opportunity to model accurately fatigue damage at multiple length scales, ranging from microns to meters. This presentation is part of a larger project where the ultimate goal is to develop such computational capabilities for metallic air and space vehicle components. Specifically, this project is developing a multiscale, mechanistic approach encompassed within a geometrical, probabilistic, hierarchical procedure. Statistically accurate geometries and physics are being represented at two length scales: the microstructural scale, on the order of 10-6 to 10-3 meters, and the component scale, on the order of 10-3 meters and larger.
The main thrust of the work presented here is toward the creation of a computational framework that explicitly models fatigue crack formation at the microstructure scale, with the test-proof material being aluminum alloy 7075-T651. Computational methods are presented that generate and discretize statistically accurate microstructure geometry models, and explicitly simulate fatigue crack formation using physics-based criteria. These methods are validated through direct comparisons to experimental observations.