Fatigue Crack Propagation Behavior of Specimens with Multiple Parallel Edge Notches at Regular Intervals

Abstract

Fatigue crack propagation tests were performed using specimens with multiple parallel edge notches at regular intervals. Fatigue pre-cracks of uniform length were successfully introduced by eccentric tension-compression loading at ten odd notches located in central part of the specimen. After pre-cracking, fatigue crack propagation tests were carried out under 4-points bending loading. Central eleven cracks of the specimen were located within the inner span of bending in which the bending stress was kept constant. These eleven cracks propagated at almost the same rate when the cracks were relatively short. After the cracks grew a few milli-meters, however, the propagation rate of some cracks was selectively accelerated while that of the other cracks decelerated. In addition, a series of finite element analyses, were performed for multiple edge cracks whose lengths were different alternately. Stress intensity factor solution for these cracks was developed and utilized to simulate experimental results. As a result, the developed solution could successfully simulate the complex propagation behavior of the multiple cracks.