SEDL / STP / STP677-EB / STP34934S

Single-Edge-Cracked Crack Growth Gage

Ori, JA
Major, USAFSan Antonio Air Logistics Center, Kelly Air Force Base, Tex.

Grandt, AF
Materials research engineer, Air Force Materials Laboratory, Wright-Patterson Air Force Base, Ohio

Pages: 17    Published: Jan 1979

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Abstract

This paper considers single-edge-cracked coupons for use with the “crack growth gage” technique for monitoring the service loading of structures that could contain preexistent cracks. Single-edge-cracked gages are bonded adhesively to larger plates which contain radially cracked holes. The bonded specimens then are subjected to various constant amplitude and one block cyclic load histories, with crack extension in both the gage and simulated structural member recorded as a function of load cycles. Cross plots of the gage and structural crack lengths at the same cyclic life are prepared and shown to agree well with predictions by a mathematical model which requires no knowledge of the actual load history.