An eta-approach to evaluate the elastic-plastic energy release rate for weld-toe cracks in tubular K-joints

Abstract

This paper proposes an energy-based η approach to estimate the elastic-plastic energy release rate for shallow surface cracks located at the weld toe at the chord crown point near the tension brace in the circular hollow section (CHS) K-joint. This approach evaluates the elastic-plastic energy release rate using the area under the load versus the load-line displacement curve for large-scale tubular K-joints, similar to the conventional η approach used to calculate the energy release rate for facture specimens described in material testing standards. The present work demonstrates that the value of ηpl equals 1 for the shallow cracks considered in tubular K-joints. The effective width (Beff), via which the remaining ligament area (Alig) is calculated, depends on the geometry of the K-joints. The plastic η approach with the proposed effective width Beff, coupled with a previous development on the nonlinear load-deformation formulation for K-joints, predicts closely the elastic-plastic energy release rate along the crack front for cracked tubular K-joints, compared to the conventional domain-integral method. © 2013 Elsevier Ltd.