Stochastic Modeling for Structural Materials Properties

High-strength gear steels used in helicopter transmission components require a long service lifetime and enhanced fatigue resistance. As the current design approach of these materials uses empirical test data for stress/life predictions, these methods do not capture the scatter in the test data nor do they isolate the dominant microstructural mechanisms that govern fatigue crack initiation. Thus, for these and many other high-performance materials, developing a set of predictive computational tools that accurately characterize fatigue resistance with its associated scatter would greatly benefit integrated computational materials engineering (ICME). QuesTek Innovations LLC proposes to develop a physics-based probabilistic fatigue crack initiation tool for high-performance helicopter gear steels. This tool will be developed and implemented within QuesTek"s Materials by Design approach, and will be sufficiently generic to be extended to a wide range of material systems. The feasibility of incorporating this physics-based probabilistic fatigue crack initiation tool by leveraging proprietary materials models and databases of high strength gear steel performance will be shown in the Phase I program. In Phase II, QuesTek will extend the physics-based probabilistic fatigue initiation model to various idealizations of inclusion arrays including realistic 3D reconstructions.