Fatigue Enhanced Cold-worked Hole FECH – Analyzer

The U.S. Navy uses a cold-hole expansion method for increasing the fatigue life of primary aircraft structures at fastener locations. The derived benefit results from compressive stresses concentrated in the metal near the perimeter of the cold worked hole. The objective of this Phase II proposal is to develop portable, light weight, quality assurance tools, based upon Eddy Current technology, that can be used to determine if a hole has been properly cold worked. The proposed products will be hand held, easy to use, and fast. (Analysis time per hole will be approximately 10 seconds) The proposed product will be very cost effective when compared to alternative inspection approaches, e.g., X-Ray Diffraction. The Phase II work will be staged to develop a hole-inspection technology that has increasing levels of quality assessment capabilities: Product 1: Provides a definitive test establishing if a hole has been cold worked. Product 2: Determines if a cold worked hole is within specifications. Prototype Product 3: Maps and images the relative values of stress or strain around a cold worked hole. Products 1 and 2 (one each) will be the deliverables for the proposed Phase II work.