Design Environment to Improve Fatigue Resistance Through Engineered Residual Stresses

The Air Force has identified a need for the development of predictive design tools that can be used to accurately determine the fatigue life of components containing both applied and engineered residual stresses and determine the optimal location and processing parameters for residual stress introduction. Impact Technologies proposes to develop an integrated analysis tool that will achieve this objective. The technical approach is based on integrating design capabilities for modeling for residual stress prediction, computational fracture mechanics based damage progression, and life prediction calculations. The approach will also take into consideration statistical variants due to modeling accuracy, loading conditions, and material behavior. This integrated approach will allow for the identification of component high stress/life-limiting regions, determination of engineered residual stress process application regions, and the computation of damage tolerance effects due to different residual stress inducing processes. BENEFIT: The development of this system would be attractive to the military as well as industry. The technology will be generic enough to be applied to any metallic structural component that contains material processing-induced stresses and documented material properties. Advanced tools that can accurately predict fatigue life of structural components subjected to residual stress while reducing experimental testing requirements can contribute to F-22 ASIP goals. In addition to F-22, this technology would be applicable to all metallic airframe structural components and could include critical drive and propulsion system components that utilize residual stress-inducing material processing. The introduction of residual stresses to increase fatigue life is used extensively in commercial aircraft structures, automotive applications, propulsion system turbines and mechanical drive components, and power generation turbines and drive components. This represents significant commercial potential for a fully developed successful Phase III product transition.