Fatigue assessment of structural elements under complex variable periodic loading

Abstract

The paper deals with the multiaxial states of stress produced by a series of short-term periodic loadings. Making use of the formulae presented in [5], each state is modelled by the equivalent state of stress with in-phase sinusoidal components. Such equivalent states can be treated by means of the classical strength theories. In this paper, Huber-Mises theory is applied to determination of the reduced stress for each equivalent state. Then, using the constant-amplitude stress model [6], the set of the reduced stresses is modelled by the long-term effective stress which enables the fatigue lifetime to be estimated from the S-N curve. Hereby the application of the conventional cycle counting method and fatigue damage cumulation rule is not required.