A Mixed Experimental-numerical Energy-based Approach for Fatigue Life Assessment in Notched Samples under Multiaxial Loading

Abstract

This paper presents a methodology to predict the fatigue lifetime in notched geometries subjected to multiaxial loading on the basis of the cumulated strain energy density. The modus operandi consists of defining an energy-based fatigue master curve that relates the cumulated strain energy density with the number of cycles to failure using standard cylindrical specimens tested under low-cycle fatigue conditions. After that, an elastic-plastic finite-element model representative of the material behaviour, notched geometry and multiaxial loading scenario is developed and used to account for the strain energy density at the crack initiation site. This energy is then averaged using the Theory of Critical Distances and inserted into the energy- based fatigue master curve to estimate the lifetime expectancy. Overall, the comparison between the experimental and predicted fatigue lives has shown a very good agreement. Keywords: Multiaxial fatigue, Fatigue life prediction, Strain energy density