Influence of interface on fatigue threshold values in elastic bimaterials

This paper describes a study of the behavior of a fatigue crack growing in one elastic material and penetrating through the interface into a second material. The study aims especially to quantify the influence of the elastic mismatch of both materials on the threshold value of a fatigue crack propagating perpendicularly to the interface. Special attention is devoted to the case of a crack touching the interface. It is shown that the corresponding threshold value is strongly influenced by the existence of an interface between the two materials. A tentative procedure suggested in the paper makes it possible to quantify the effect and determine the dependence of the threshold value of a fatigue crack growing through the interface on the Dundurs parameters α and β. sults are applied to a body with a protective layer, and the corresponding fatigue threshold value for a crack with its tip at the interface is estimated. This makes it possible to decide whether the crack will stop at the interface or continue growing into the second material. sults generally contribute to a better understanding of the failure of bi-material bodies and of structures with protective layers.