Fatigue crack propagation behavior in four-points bending specimens with multiple parallel edge notches at regular intervals

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. Fatigue crack propagation tests were carried out under four-points bending loading. Obtained crack propagation behavior was simulated by using newly developed stress intensity factor equations for multiple parallel edge cracks with alternately different lengths. Simulated results showed a good agreement with the experiment for specimens with relatively broad crack intervals, while for specimens with narrow crack intervals showed a different tendency from the experiment when crack lengths became long.