Propagation of Fatigue Cracks in Parallel with the Interfaces of Metal Composites

Abstract

Push-pull fatigue tests were conducted on butt-bonded three layer composite plates composed of iron and copper, to study the effect of the difference in elastic moduli between the constituent materials on the behavior of the fatigue crack propagating in parallel with the interfaces. It was observed that, when a crack propagated in the core iron which was flanked with copper plates having a lower elastic modulus than iron, the growth rate was higher than that of a crack propagating in the monolithic iron plate, and that, for the crack propagating in the core copper which was flanked with iron plates, the growth rate was lower than that of the crack propagating in the monolithic copper plate. These observations agreed with the trends of k_I-value in each composite plate obtained by numerical computations based on F. Erdogan's analytical method and on the finite element method.