Mixed-Mode Fatigue Crack Growth in Stainless Steels Under Biaxial Loading

Abstract

Mixed-Mode fatigue crack propagation tests were carried out in stainless-steel cruciform specimens in which a center initial crack oriented at 45 deg was loaded biaxially. When the loadings were in-phase, the crack was deflected with the initial crack growth angles less than 50 deg and when they were out-of-phase, it was branched with the initial crack growth angles larger than 50 deg. In all the cases, the deflected or branched cracks propagated in Mode I, namely ΔKII was almost always zero along the crack paths. The relationship between deflected or branched cracks during propagation was also analyzed.

The minimum shear stress range criterion and its application to crack orientation prediction in incomplete contact fretting problems

“…However, the criterion of max(∆k * I ) predicted better results in a 35NCD16 steel. Other authors have pointed out that, under non-proportional conditions, a crack follows a trajectory minimizing ∆K II [12][13][14][15][16]. For example, Kitagawa et al [12] and Qian et al [15] found that ∆K II was almost zero along the crack paths in cruciform specimens under biaxial out-of-phase loading.…”

Experimental study of I + III mixed mode fatigue crack transformation propagation

“…Tong et al 12 studied fatigue threshold behaviour under Mode III and in‐phase mixed Mode III and Mode I loading conditions in a 3.5%NiCrMoV steel, using V‐notched and pre‐cracked cylindrical bar specimens at load ratios R = 0.1 and −1. Qian et al 13,14 tested mixed mode fatigue crack growth in stainless steels under biaxial loading and found the crack was deflected or branched depending on the initial crack growth angle.…”

Cruciform specimens used for determination of the influence of T-stress on fatigue crack growth with overloads on aluminum alloy Al 6061 T651

“…A phase shift of 180° in time between them theoretically induces a pure mode II loading. Practical tests show mainly a kink or branch in mode I direction [9]. Several incipient cracks outside the center of the specimen can be used, for example, for simulating loads on rivet holes [10].…”