Measurement of Residual Stresses in Difficult Locations

The Air Force identified measuring stresses in hard-to-access locations as a major concern. Detrimental stresses in these locations lead to expensive loss of use, inspection and repair costs, and potential loss of aircraft and personnel.X-Ray diffraction--a proven technique for measuring stresses--has been taken from the laboratory to field use on large structures. However, current systems do not permit measurements in hard-to-access locations.TEC has successfully reduced the measurement head to fit inside a 6-inch diameter hole and obtain the correct stresses in aluminum. TEC proposes to reduce the measurement head to approximately 4 inches and measure stresses in aluminum, ferritic/martensiticsteels, and titanium alloys. Elements are in place for successfully measuring austenitic steels and nickel, provided a miniature manganese x-ray tube is obtainable.The ultimate goal is to produce a hand-carried, rugged, low-power consumption instrument that can correctly measure stresses in difficult-to-access locations. Emphasis will be on power requirements, personnel safety, measurement speed, data availability,ease of use and data interpretation.The proposed instrument should result in significant maintenance savings and has commercial applications to virtually all industries relying on common engineering alloys for safety-related functions.