Experimental study of fatigue crack propagation under programmed spectrum loading

Abstract Fatigue crack propagation behavior under programmed spectrum loading is significantly influenced by load history. There are partial arrest phenomena in the propagation during overload ratios 1.4 through 2.2, so the retarded zone is divided into two parts: the partial arrest zone and the propagation-regained zone. A formula for partial arrest cycles number is proposed. On the basis of the crack closure concept, an experimental formula is proposed to calculate the fatigue life. The result is compared with other predicted and experimental data. It offers a good prediction.