Fatigue Crack Initiation Behavior under Biaxial Loading

摘要

Many engineering components and structures in service have been found to be damaged by multiaxial cyclic loads. It may not be easy to predict and analyses this fatigue damage because the various combinations of the applied loads shown in multiaxial loading make the local stress states and the damage significantly complex. Therefore, knowledge on fatigue behavior under multiaxial loading may be necessary for prediction and assessment of the fatigue damage. The fatigue initiation behavior under the multiaxial fatigue loading, including proportional and non-proportional loading, has been studied using a smooth specimen [1 ～ 5]. In general, the behavior, including the direction and the fatigue life, under the proportional loading is governed by the maximum shear stress (or strain) even though some other parameters are suggested. Under the non-proportional loading, the loading type and phase difference can influence on the fatigue crack initiation behavior [7 ～ 9]. Zhang and Akid [5] showed that the crack initiation direction varied with the biaxial mean stress under cyclic tensile and torsion loading and the direction was along the plane of the maximum shear strain.