Roughness-induced stress shielding effect in fatigue crack propagation under Mode II loading

•Roughness-induced stress shielding effect is evaluated quantitatively.•Cyclic Mode II loading fatigue test is performed on a small textured material.•Fatigue crack failure surface morphologies are used for the evaluation.•Results obtained by specimen side surface observation are confirmed by fractography.•Fatigue crack propagation mechanism under cyclic Mode II loading is discussed. Roughness-induced stress shielding effect under cyclic Mode II loading caused by fracture surface roughness, i.e., the effect of decreasing loading stress intensity factor K, is investigated. A fatigue crack propagation test by applying cyclic Mode II loading on a small textured material is performed. The decrease in K is a few percent quantitatively, and the decrease is sufficiently small to ignore. Using the failure surface observation results, we discuss the mechanism of the fatigue crack propagation during cyclic Mode II loading on the textured material and validate the repeated crack propagation mechanism of damage accumulation, void formation, and coalescence.