Fatigue Crack Propagation under Random Loading

Abstract

Fatigue damage caused by random loading has since long been a subject of interest both to researchers and engineers. Most work in this field deals with the problem of fatigue crack initiation while theories for crack propagation under random loading have not reached the same level of development. During the recent years, however, several authors have addressed this problem and now different approaches exist. In most cases a deterministic relation between the stress-intensity factor and the crack growth rate is assumed and the random nature of the problem enters by permitting some quantities to be stochastic variables. This type of approach is used e.g. by Miller [1] and Nilsson [2]. A different method has been proposed by Kozin and Bogdanoff [3] who employed a Markoff chain model.