Cumulative Fatigue Damage by Block Loading with p-Distribution (2 nd Report)

Abstract

In view of non-conservative prediction of cumulative fatigue life calculated by Miner's and Haibach's methods, the authors proposed in a previous paper a new model providing better and conservative prediction, although it was limited in application to only the bi-linear fatigue diagram in high cycle fatigue regime. If a fatigue diagram will be required to be expressed for a wide range of fatigue life from very low cycle to high cycle regimes, it is a convenient way to express the diagram by Stromeyer's expression.The previously proposed model is developed in the present paper so as to be applicable to Stromeyer's as well as hi-linear expressions of a basic fatigue diagram in undamaged condition. The newly proposed model in this paper is based on a concept consisting of two assumptions ; (i) Fatigue damage will be accumulated as a power function of cycle ratio, and (ii) Fatigue strength at infinite fatigue life or at 107 cycles will decrease functionally according as accumulation of fatigue damage.