FATIGUE-CRACK INITIATION AND PROPAGATION FROM HOLE DEFECTS

The aim of this study is to investigate the interaction of two hole de fects affecting fatigue crack initiation life and propagation behavior . The location of two hole defects was characterized by an angle of al ignment and the distance between the centers of two hole defects. The fatigue cracking behavior is studied under bending for Al 5086. When d efects are located close to each other, the fatigue crack initiation l ives are varied with their relative locations. In the experiments, the area of local plastic strain strongly played a role in the fatigue cr ack initiation lives. Therefore, the authors introduce a parameter wh ich contains the plastic deformation area at stress concentrations and propose a fatigue crack initiation life prediction curve. in addition , the directions and propagation rates of fatigue cracks initiated at two hole defects were studied experimentally.