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Fretting Fatigue Under Block Loading Conditions

出版	ASTM International, 2003
URL	http://books.google.com.hk/books?id=Rrp8zgEACAAJ&hl=&source=gbs_api

註釋The effect on fretting fatigue life of applying periodic overloads and two-level block loading has been investigated, and the applicability of Miners damage accumulation under fretting fatigue loading conditions has been tested. The application of single 150% overloads at given intervals had a considerable effect on life, with life extensions on the order of two being observed for overload application intervals of 102 to 104 cycles. Miner's law was unable to predict the life extensions found. Two-level block loading spectra were applied in which the single overloads were made equivalent to a high-level loading block consisting of a single cycle. The effect of increasing the number of overloads in a high-level block was investigated. It was observed that as the proportion of cycles in the high-level block was increased, the damage accumulation became dominated by the high-level loading. The effect of lower-level constant amplitude loading was to extend life and delay the damage process. A hypothesis based on the contact stress analysis and tangential force hysteresis loops has been proposed and successfully explains all of the variations in fretting fatigue life observed. Miner's law cannot be confidently applied for the loading conditions tested.