Effect of wrought product thickness and stress ratio on fatigue crack growth behavior

Effect of thickness on fatigue crack growth (FCG) behavior has been investigated at varying stress ratio in a quaternary Al-Li alloys. The thickness has been observed to influence FCG behavior in two opposite ways, depending on stress ratio. The crack closure concept has been invoked to rationalize the observed behavior. The roughness-induced crack closure is the main governing mechanism in the alloy under investigation. Factors such as fracture surface asperity size and severity of plane strain condition have been argued to affect the extent of crack closure, and consequently, fatigue crack growth behavior.