CRACK PROPAGATION IN LOW-CYCLE FATIGUE OF MILD STEEL

An investigation was made of crack propagation in low-cycle fatigue of mild-steel plate specimens and has indicated that during crack propagation the type of loading cycle will affect markedly the fatigue behavior. Several types of reversed loading cycles have been included in the investi gation, namely constant load, reduced loads and constant stress. In the constant-load tests the stress increases throughout the test as the crack propagates, and the rate of crack propagation continuously increases. If the load range is reduced throughout a test (reduced-load test) so as to produce constant net-section stresses, the rate of crack growth will decrease throughout the test. (Author)