Fatigue Enhanced Cold-worked Hole FECH - Analyzer Navy SBIR FY2005.2 Sol No.: Navy SBIR FY2005.2 Topic No.: N05-120 Topic Title: Fatigue Enhanced Cold-worked Hole FECH - Analyzer Proposal No.: N052-120-0385 Firm: Resodyn Corporation 130 North Main Street Suite 600 Butte, Montana 59701 Contact: Steve Galbraith Phone: (406) 497-5223 Web Site: www.resodyn.com Abstract: 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. Benefits: A reasonably priced hand held portable device capable of quantifying the effectiveness of the cold hole expansion process will provide a quality assurance tool to manufacturers and field repair depots that does not exist today. Basing the technology solution for a portable quality assurance tool founded on a novel approach of eddy current techniques, manufacturing of a final product and introduction to the market can occur quickly by using existing manufacturers as component suppliers. Eddy current devices today are established as safe, reliable, and portable which meets the requirements set forth by the solicitation. The proposed technology to map out residual compressive stresses using eddy current technology has an additional benefit as eddy currents can detect material flaws. This ability can also be easily implemented into the same portable tool used for determining residual stresses. Return