Paper

Paper Name    Overload induced retardation of the fatigue crack growth of polycarbonate
Author    Qin-Zhi Fang, T.J. Wang, Hui-Min Li
Publication/Completion Time    2007-09-05
Magazine Name    International Journal of Fatigue
Vol   
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Paper description    The effect of single overload within an otherwise constant amplitude loading sequence on the retardation of fatigue crack propagation (FCP) behavior of polycarbonate (PC) was experimentally investigated in this paper. An improved compliance method was employed to measure the length of a fatigue crack, and optical and scanning electron microscopes (SEM) were used to observe the features of crack surface and crack tip deformation. It was shown that there was a small crack increment during the application of overload. After that, the crack growth rate reduced to a low level quickly, and then increased gradually until it reached the normal level of crack growth rate. The waveform and overload ratio of the single overload had different effects on the FCP of PC, with the former having slight effect, and the latter larger effect. The overload-induced retardation of fatigue crack growth was mainly due to the formation of crack tip craze zone. The relationship between overload retardation ratio Rr and overload ratio Ro had been obtained in the form of Rr ¼ 0:95 þ 0:056 R2:72 o .  2007 Elsevier Ltd. All rights reserved.