HILL ENGINEERING LLC — Department of Defense SBIR Phase I: N162-085

Description

In modern military and commercial aircraft turbine engines, high cycle fatigue and foreign object damage are significant contributors to sustainment costs. Foreign object damage is most acute on the thin leading edges of titanium airfoils. Objects inadvertently ingested in the engine include small stones, aircraft fasteners, and birds. When these objects impact the rotating titanium airfoils, damage such as dents, nicks or tears result. Left undetected or uncorrected, this damage provides an ideal initiation site for high cycle fatigue cracks to form and propagate within the airfoil. Once these cracks reach a critical length, the airfoil will fracture resulting in significant secondary damage and a possible in-flight shutdown of the engine. The proposed program will develop an analytical tool for the design and repair of high cycle fatigue resistant integrally bladed disk airfoils. The analytical tool will be able to account for residual stresses while incorporating the probabilistic variability of airfoils. The analytical tool will serve to support airfoil design and will also be applicable to various airfoil repair cases.