Fretting fatigue of anisotropic materials at elevated temperatures.

摘要

The purpose of this research is to develop an experimental procedure to characterize the contact between blade and disk in aircraft turbo-machinery and to develop a model to predict the life of components based on contact conditions. An experimental setup has been developed to conduct fretting fatigue tests at 610°C. Fretting fatigue lives are characterized for the contacting pair of IN100 and single crystal nickel subjected to a range of loading conditions. A well characterized set of experiments has been conducted to obtain the friction coefficient in the slip zone. Material principal axes and the crystallographic plane of fracture were determined. A robust quasi-analytical approach, based on solution to singular integral equations, has been used to analyze the contact stresses. Different multi-axial fatigue parameters have been investigated for their ability to predict the initiation life of the specimens, after applying a stressed area correction factor using weakest link approach. Multiaxial fatigue parameters also predicted crack nucleation at the edge of contact, consistent with observations of the fractured specimens. Crack propagation lives were evaluated using conventional fracture mechanics, after making certain assumptions to simplify the problem. Total life was estimated as the sum of nucleation life and propagation life. These predicted lives were compared with experimentally observed failure lives. The quality of the comparison provides confidence in the notion that conventional life prediction tools can be used to assess fretting fatigue at elevated temperatures.