A fracture mechanics approach to high cycle fretting fatigue based on the worst case fret concept: II. Experimental evaluation


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Abstract

This is Part II of a series of two papers that describe the development and evaluation of a fracture-mechanics based life-prediction methodology for treating fretting fatigue in structural alloys. In Part I, the development of a life-prediction methodology based on the worst case fret (WCF) concept is presented with parametric calculations to illustrate the capability of the method. In this paper, the results of an experimental program designed to evaluate the applicability of the WCF model to treating high-cycle fretting fatigue in Ti-6Al-4V are described. High-cycle fretting fatigue tests were performed on Ti-6Al-4V at ambient temperature and at 2100 Hz. A flat pad with rounded edges or a cylindrical pad on rectangular specimens was fretted using either single or multiple cyclic load steps. Each load step was conducted for 107 cycles before the cyclic load range was increased. This process repeated until fretting fatigue specimen failed. The existence of nonpropagating cracks was identified using metallography and fractography. The experimental results were used to assess the accuracy of the WCF methodology.

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