The relevance of crack closure and crack initiation evaluation techniques to small fatigue crack behaviour

摘要

Interest in small fatigue cracks has waned somewhat over the last few years, at least partly because of a perceived lack of relevance to life prediction in general structural engineering. However, cross-overs in fatigue performance of aluminium weldments, as life increases from around 10{sup}5 cycles to 10{sup}7 cycles, indicate that crack initiation and early crack growth are important to the overall life. Significant work therefore remains to be done in understanding small crack behaviour, particularly under multi-mode variable amplitude loading. Progress is hindered by certain experimental difficulties related to monitoring growth, measuring and interpreting closure phenomena, and the effect of certain crack generation techniques on observed phenomena. The paper briefly reviews some of these issues.