A modification of distorion - energy strength theory at static-periodic loading conditions

The aim of this paper is to present the analytical procedure capable of dealing with complex stress patterns in the high-cycle fatigue regime formed simultaneously by static fatigue regime formed simultaneously by static and periodic loads. It consists in modelling the actual multiaxial stress by means of the equivalent in-phase stress, transforming the equivalent stress into the reduced stress, and in using the reduced stress to fatigue assessment of the structural element by means of the formulae accepted in the case of simple sinusoidal stress. The reduced stress is determined with the aid of the average-distortion-energy strength hypothesis based on the distortion-energy strength theory. Thereby the mean stress is taken into account and the cycle counting is avoided.