Analytical vs Numerical Calculation of Fatigue Life for Different Welded Joint Regions

Abstract

This research will show the analytical way of determining the remaining life of a welded joint with a fatigue crack initiated in its heat affected zone. The calculation will be divided into two stages, since the fatigue crack propagated through the heat affected zone, and then through the parent material. The analysis will be related to specimens with different fatigue properties taken into account for both regions. These calculations included a number of models, since different crack lengths were used for the heat affected zone and the parent material. There were three pairs of different HAZ vs PM fatigue crack lengths, always with the assumption that the total crack length is 5 mm, due to measuring range of the used measuring foils. The aim of this analysis was to apply method typically used in fracture mechanics in order to determine the number of cycles in a welded joint with an initiated fatigue crack, depending on a number of parameters. Obtained results were then compared to the results from the numerical analysis for the same cases. While the total number of cycles was mostly unaffected by these changes, some noticeable differences were observed between individual welded joint regions in question, the heat affected zone and the parent material.