Cumulation of Effects in Calculating the Deterioration of Fatigue Loaded Structures

Abstract

It has been introduced and analyzed on literature-based relations that calculating the deterioration produced by cyclic loading with normal stresses can be actually calculated. Based on the principle of critical energy, deterioration has been expressed as a power function. The deteriorations thus calculated can be summed up in order to obtain the cumulated effect of the external loadings. There have been established expressions for the deterioration produced by the action of: a single cyclic stress, several blocks of cyclic stresses with normal and/or shear stresses by taking into consideration the cumulated effect of vibrations and/or corrosion, cracked or crack free structures. The relations refer to both samples as well as to actual structures with stress concentrations. One suggested a procedure as to apply the obtained results to the case of random loading of a structure. The calculation examples show how the article makes use of the relations proposed.