An understanding of very high cycle fatigue of metals

For modern technical applications like cars, trains, and aircrafts, the durability of some components is between 10(8) and 10(10) cycles. However, there are very few experimental results beyond 10(7) cycles, where the standard fatigue limit is predicted using statistical approaches. Generally, it is said that the probability of failure is given with the Gaussian curve, which is not always true. The S-N curves of metallic materials have been assumed by hyperbolic relationships. However, in some cases the asymptote is not really horizontal. That means that the fatigue strength at 10(6) cycles is higher that at 10(8) cycles. Thus, the S-N curve in the gigacycle regime must be determined in order to guarantee the real fatigue strength and safe life of mechanical components. In this paper, the state of the art in this field is summarized through our own results. (C) 2003 Elsevier Ltd. All rights reserved.