Cavitation Peening to Enhance Turbine Engine Component High Cycle Fatigue Life

Cavitation peening is a novel method of inducing deep residual compressive stresses in components by sweeping an ultra-high pressure waterjet across the surface. The process is fast, very inexpensive and can be readily applied to a wide variety ofgeometries, including difficult to access surfaces such as intregrally bladed rotors (Blisks) and impellers. It is estimated that this new process will be less than 2% the cost of laser shock peening while achieving residual stress profiles twice as deepas conventional shot peening. It is also expected to achieve high fatigue life improvements of 3X and damage tolerance improvement of 15X. The proposed work will demonstrate the ability of cavitation peening to impart residual compressive stresses ontitanium and other alloys for small engine components. A peening work station will be built in Phase II for peening small engine components and fatigue benefits will be quantified and an economic analysis conducted to demonstrate benefits over alternateprocesses. In addition to greatly enhancing fatigue life and damage tolerance of turbine engine components, the process can also be applied to automotive gears, bearing races, engine components, airframes, springs, railroad tracks, and other fatiguecritical components. The market is expected to be as least as large as the $200M conventional peening business. Longer fatigue life and greater damage tolerance will result in fewer aircraft lost from engine failure and reduced maintenance costs and longercomponent life. Because the beneficial induced stresses are ten times deeper than conventional shot peening, the benefits to fatigue life will be dramatically improved. This feasibility of this process has been demonstrated in a nuclear power applicationand the proposed work will broaden the applications to turbine engines and power train components.