Influence of Ambient Air on Nucleation in Fretting Fatigue
SourceFretting damage often participates in failures caused by multiple site damage (MSD) as a nucleation process. Fretting itself is an extremely complex degradation process consisting of a combination of mechanical and chemical attacks. In order to avoid damage it is essential to understand which dominating parameter influences the crack nucleation.
The topography of the fracture surface, as well as changes in microstructure provide information about the dominant damage mechanism. An exact differentiation of the predominant damage mechanism can be established by microscopic and metallographic investigations.
Two service failures in axles for ski lifts, which suffered from fretting fatigue, are discussed. Though the macroscopic findings are very similar, the microscopic investigation indicates a completely different crack nucleation mechanism.