Investigation of the Effect of the Roughness-Induced Crack Closure on the Fatigue Crack Propagation Behavior of Hot-Rolled Steels under Mixed-Mode Loading Conditions

It is reasonable to apply crack closure concepts, i.e. roughness-induced crack closure, to understand the crack propagation behavior under mixed mode loading conditions.In this paper, the characteristics of fatigue crack propagation under mixed-mode loading is studied using the concept of roughness-induced crack closure, and a model of the variation of the crack opening ratio is proposed based on multi-variable statistics.In addition, fracture surfaces are examined by C-scan and classified into four stages to quantify the effect of crack closure.The roughness parameter based on the highest intensity reveals the effect of roughness-induced crack closure on the fatigue crack propagation.