Estimating the fatigue behavior of welded joints in the VHCF regime

Abstract

Purpose

The present work aims to deal with a very high cycle fatigue (n=10⁹ cycles) of gas metal arc welded joints, subjected to a multiaxial and non‐proportional loading. Different design codes and recommendations can greatly reduce the analysis effort in the design of welded structures providing a suitable balance between computational accuracy and ease of use for many industrial applications. However, various assumptions have to be made in a conservative way making this approach less accurate. This paper deals with a refined fatigue assessment, which considers the most important aspects for welded joints and provides an accurate lifetime prediction of welded structures.

Design/methodology/approach

For an accurate prediction of the total lifetime of welded components the information about the material state and the welding induced residual stresses on weld toes is essential. If the surface condition after welding is poor in this area, which is usually the case, the presence of defects can be assumed and the fatigue crack nucleation process can be neglected. The microstructural threshold for initial crack propagation can be therefore used as a lower bound for the fatigue limit prediction.

Findings

Based on the results from the simulation of a welding process and a post‐weld heat treatment in combination with a fracture mechanics approach, this work successfully attempts to reproduce a fatigue behavior, which was observed at the fatigue tests of the multi‐pass single bevel butt weld.

Originality/value

The proposed approach is able to predict accurately the fatigue strength of welded structures and to achieve the full cost and weight optimization potential for industrial applications.

Citation

Krasovskyy, A. and Bachmann, D. (2012), "Estimating the fatigue behavior of welded joints in the VHCF regime", International Journal of Structural Integrity, Vol. 3 No. 4, pp. 326-343. https://doi.org/10.1108/17579861211281164