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Advances in Fatigue Test Technology,
LOCKHEED-CALIFORNIA CO BURBANK
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The report summarizes work directed at the verification of currently used compliance relationships for the wedge-open-loading WOL specimen geometry frequently used in fatigue crack propagation testing. An overview is given of compliance curve fitting procedures. A new procedure is proposed which appears to offer significant advantages. Compliance calibration results are presented for Ti-6Al-4VRA and Ti-6Al-4VBeta alloys. Analytical procedures for obtaining the stress intensity calibration function C sub 3 from experimental compliance results were compared and the proposed three parameter fit was found to be superior. The advantages of this proposed data analysis procedure are small numbers of constants, relationship between normalized compliance compliance x modulus x thickness and normalized crack length crack lengthspecimen width is differentiable and invertible, consistency with physical reasoning, and discussion of possible differences in compliance due to material differences can be restricted to a single parameter.
APPROVED FOR PUBLIC RELEASE