Fatigue Life Prediction in Aluminium Welds for Thin-sheet Structures

Abstract

Current codes and recommendations used for fatigue analysis of welded joints are mainly developed for the civil and maritime sectors where the material thickness used is typically more than 5 mm. This is a problem when studying welded components in the automotive industry where the general structure is thinner. This thesis aims to propose and compare two methods with different level of modelling detail developed for thin-walled structures with a material thickness of less than 5 mm. The methods proposed are found from a study of relevant research and are implemented on two different joints. A series of different load cases were simulated and a comparison of the results was made with the aim of finding any discrepancies between the methods, both concerning fatigue resistance data and stress extraction. The findings suggests that the major deviation between the methods is related to the fatigue resistance data which is determined from different experimental sources. More interesting was the difference between the methods related to the stress extraction where the deviation in the results depends on the ratio between membrane and bending stresses in the welded joints.