Stress Intensity Factors of Semi-Elliptical Cracks in a Tubular Welded Joint Using Line Springs and 3D Finite Elements

Abstract

A tubular welded T-joint containing a series of semi-elliptical cracks of increasing depth located near the chord-brace intersection, has been analyzed using shell elements with the cracks modeled by the line spring concept of Rice and Levy [1]. The same problem has also been modeled with 20-noded bricks allowing the stress intensity factors to be determined by virtual crack extension. The direction of crack growth has been determined both using off-axis virtual crack extension and solutions for kinked cracks, to determine the orientation which maximize either the strain energy release rate G or K I . The calculated crack path agrees with reported experiments [2]. Finally, the stress intensity factors for straight and curved cracks in single welded joints have been compared in terms of their effective depth.