Parametric equation to predict the SIF of cracked tubular T/Y-joints

Abstract

Accurate prediction of the Stress Intensity Factors (SIFs) along the crack front plays an important role in the fatigue life estimation of steel structures. As far as the authors know, all of the SIF parametric equations presented in literature ignore the influence of the crack propagation angle in their equations. Therefore, this paper focuses on deducing a new parametric SIF equation for circular hollow section T/Y-joint with semi-elliptical surface crack, with the consideration of the effect of the crack propagation angle (θcr) on the stresses along the crack front for the first time. The location of the hot spot stress along the weld toe of T/Y-joints under axial loading is firstly determined. Then, a robust finite element (FE) mesh generator is created, calibrated and employed in analysis procedures of 21,600 tubular T/Y-joints. Meanwhile, nonlinear regression analyses are carried out to develop SIF parametric equation of welded tubular T/Y-joints. The proposed parametric equation is found to agree well with the FE results and the experimental results presented in literatures. Additionally, it gives more accurate prediction of the SIF than the existing parametric equations. The error analysis of the proposed equation proves that 90% of the results have errors less than15% and 99.7% of the results have errors <30%.