Study on the effect of loading conditions on the fracture behavior of pipeline with girth weld

Abstract

There is increasing attention on the fracture of pipelines with girth weld, as a result of the accidents caused by additional loads occurring occasionally. However, there is little research on the dynamic cracking behavior of girth welds under different load forms. To further understand the fracture process of girth weld, the crack initiation and dynamic fracture behavior of welded pipe under pure bending load are firstly analyzed by numerical simulation method based on Gurson-Tvergaard-Needleman (GTN) model. It is found that the bearing capacity of the pipeline is reduced due to the existence of the weld. Subsequently, the distribution of the axial stress and strain and the fracture morphology are analyzed, which indicates that the softening of HAZ donated to the brittle fracture of the pipe. The opening angle and displacement are studied respectively, from which can be obtained that WOD is linearly related to the deflection change, and the fracture resistance of the pipe girth weld can be characterized by the slope. Finally, the bearing capacity and fracture toughness of the pipe in different loading conditions are analyzed. The results show that the bearing capacity of pipeline girth weld is greatly reduced due to shearing.