Fatigue Enhanced Cold-worked Hole FECH - Analyzer

The Navy routinely uses a structural strengthening technique called cold hole expansion for increasing the fatigue life of primary aircraft structures that are fastened together. This process creates beneficial compressive stresses around the hole. However, variances in the process produce inconsistent results and no means exist to nondestructively quantify the process effectiveness. Resodyn Corporation proposes the development of technology based on a novel eddy current circuit and coil array that will map stress contours around the hole. Fundamentally, the circuit and coil arrangement is designed to be sensitive enough to measure changes in conductivity across the stress field resulting from various stress states around the hole and correlate the conductivity measurements to stress values. This approach has advantages over contemporary methods because it can be readily implemented into a small hand held probe that can provide either quantitative or go / no-go metrics in the field. The team assembled to research this technology includes a scientific consultant who has previously demonstrated feasibility of the proposed approach on a different application, the developer and major supplier of hole expansion tooling, a manufacturer of eddy current equipment, and product development engineers with demonstrated product to market success.