On the growth of cracks at the fatigue threshold following compression overloads : Role of load ratio

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Original languageEnglish
Pages (from-to)11-17
Journal / PublicationMaterials Science and Engineering
Issue number1
Publication statusPublished - Sep 1985
Externally publishedYes


Studies have been performed on the effect of single compression overload cycles on the role of crack closure during near-threshold fatigue crack growth in ingot metallurgy aluminum alloy 7150-T7, specifically with respect to the role of mean stress or load ratio R (= Kmin/Kmax). It was found that large compression or simple unloading cycles, applied to cracks arrested at the fatigue threshold at R = 0.75, had no detectable effect on crack closure or crack growth behavior. This is in contrast with previous studies at R = 0.10 where arrested threshold cracks subjected to such compression cycles (of magnitude five times the maximum tensile load) were seen to recommence growth immediately, consistent with a measured reduction in closure. Such results are discussed in terms of the major origins of crack closure in this alloy. © 1985.