A fretting crack initiation prediction taking into account the surface roughness and the crack nucleation process volume

摘要

This paper presents an experimental study of the fretting crack nucleationthreshold, expressed in terms of loading conditions, with a cylinder/planecontact. The studied material is a damage tolerant aluminium alloy widely usedin the aerospace application. Since in industrial problems, the surface qualityis often variable, the impact of a unidirectional roughness is investigated viavarying the roughness of the counter body in the fretting experiments. Asexpected, experimental results show a large effect of the contact roughness onthe crack nucleation conditions. Rationalisation of the crack nucleationboundary independently of the studied roughnesses was successfully obtained byintroducing the concept of effective contact area. This does show that thefretting crack nucleation of the studied material can be efficiently describedby the local effective loadings inside the contact. Analytical prediction ofthe crack nucleation is presented with the Smith-Watson-Topper (SWT) parameterand size effect is also studied and discussed.