Rain-flow fatigue damage for transformed Gaussian loads

Igor Rychlik and Sayan Gupta

Abstract:: Fatigue damage due to a special class of non-Gaussian broadband loadings is considered. Specifically, the loadings are considered to be non-monotonic transformation of stationary, Gaussian random processes. A linear damage accumulation rule is assumed and the rain-flow cycle counting method is considered. Analytical expressions are developed for estimating the expected rain-flow fatigue damage. Easy to compute approximations, in terms of the upper bounds for the expected rain-flow fatigue damage, have been developed. The proposed method has been demonstrated through a set of illustrative numerical examples. The method developed is of use in estimating the time variant reliability of ageing structures under random dynamic loadings.

Key words:: expected fatigue damage, rain-flow cycle counting, non-Gaussian process, non-monotonic transformations