A critical investigation of techniques for stress determination and equivalent static analysis in fatigue life estimation

Abstract

This study entails the fatigue analysis of a complex plate-like structure subjected to random loading. The stress and fatigue life assessment is performed by means of experimental strain gauge measurements, finite element analysis and a quasi-static fatigue assessment procedure known as the fatigue equivalent static load (FESL) methodology. Firstly, the integrity of shell elements for accurately capturing the stiffness properties and stress distribution in the vicinity of welds is investigated. Furthermore, the stress response of the structure to random dynamic loading is investigated and validated in terms of its suitability for assessment by the FESL methodology. Nominal stress and hot-spot stress fatigue life predictions are made, based on measurements as well as the FESL procedure. The viability and integrity of the FESL methodology is critically assessed after which the actual fatigue life of the structure under particular loading conditions is determined for comparison.