Evaluation of the Crack Gage Concept for Monitoring Aircraft Flaw Growth Potential.
Final rept. 1 Jul 77-1 Dec 78,
BOEING WICHITA CO KS
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The results of a test program to evaluate the ability of a bonded-on precracked coupon to monitor the growth of flaws in the basic structure are included. All testing utilized 7075-T651 aluminum from a single plate. Both constant thickness and stepped crack gages were evaluated. Evaluation of a wide range of sensitivity in crack gage crack growth response was made. Structure flaws of 1 corner flaw at a hole, 2 through flaw at a hole, and 3 center notch flaw were evaluated. The cyclic test loading included constant amplitude of two R ratios and three representative aircraft usage flight profiles. Strain gage instrumentation was used to measure structure stresses and load transferred into the crack gages. Author