Influence of Weld Toe Radii on Fatigue Life Prediction

School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

^* Corresponding author: kstsang@ntu.edu.sg

Abstract

A study was carried out to investigate the influence of the weld toe radii on the fatigue strength of butt welded joints loaded in bending and tension. Fatigue analysis starting from weld toe cracks in marine and offshore welded pipe specimens were conducted using cut-out four-point bend fatigue test specimens. Fatigue life can be enhanced by reducing the local stress concentration generated by weld toe radius effects. This study investigated the effect of different weld toe radii on the stress intensity factor at the region of the weld toe through Finite Element Analysis (FEA). FEA was used to model a butt welded steel plate extracted from a pipe subject to tension and four-point bend loading. Semi-elliptical surface (SESC) cracks were modeled at the weld toe region with different SESC crack depth and surface crack length. Four weld toe radii and two modes of loading were investigated. The stress intensity factors, weald toe magnification factors, or M_kc and M_ka are reported and used for fatigue life prediction.