SEDL / STP / STP1220-EB / STP14610S

Shear Fatigue Crack Growth in Large Grain Polycrystals

Chen, Q
Solid State Science and Technology, Syracuse University, Syracuse, NY

Liu, HW
Solid State Science and Technology, Syracuse University, Syracuse, NY

Pages: 17    Published: Jan 1995

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Abstract

Fatigue cracks are often nucleated as small shear cracks. The propagation of such a crack often results in a crack plane that is inclined to the loading axis in such a manner to induce a mixed Mode I, Mode II, and Mode III crack-tip field. In this study, crack growth rates of Mode II and Mode III shear cracks as well as Mode I cracks in large-grain Al 7029 aluminum alloy were measured. The crack-tip resolved shear stress intensity factor, K^RSS, was defined and calculated for each slip system in a crystal. The result of the study shows that K^RSS is capable of characterizing the shear decohesion mechanism of crack growth, explaining the morphological features of a crack surface, and correlating with shear crack growth rate.