Elastic correction of fatigue crack growth laws

Abstract

Fatigue crack growth (FCG) is usually studied assuming that ΔK is the driving parameter. An effective ΔK is considered in the presence of crack closure. However, after crack opening, there is an elastic regime that does not contribute to FCG. The objective here is to quantify this elastic range of ΔK, ΔKel, for different loading conditions and material properties. The yield stress was found to be the most important material parameter, followed by the hardening exponent. A linear decrease of ΔKel with ΔK was found for the 7050‐T6, 6082‐T6, and 6016‐T4 aluminium alloys, while the 304L stainless steel presented a slight increase. On the other hand, the increase of Kmax was found to increase the elastic fatigue range. Relatively high values of elastic range were obtained for the plane strain state, compared with the plane stress state.