Equivalent life distribution and fatigue failure probability prediction

Equivalent fatigue life distributions under two-level cyclic stress are ana lyzed experimentally, and a model of describing equivalent life distributio n is presented. Based on the equivalent life distribution model, an "equiva lent damage-equivalent life distribution" method is developed to predict fa tigue failure probability under variable amplitude loading. The underlying principles are fatigue damage accumulation rule and "load cycles-fatigue li fe" interference theorem. In the equivalent damage-equivalent life distribu tion method, two parameters, i.e. mean and standard deviation of the (equiv alent) life distribution are used to describe cumulative fatigue damage eff ect. A basic feature of the equivalent damage-equivalent life distribution method is its capability of reflecting the loading history dependent change of the equivalent life distribution. Tests under multi-level stress show a good agreement between predicted fatigue failure probability and the test results. (C) 1999 Elsevier Science Ltd. All rights reserved.