Wei Cui
Wei Cui, Northeast Petroleum University, China
Title: Numerical simulation of the interference effect of double cracks in X80 pipeline weld
Biography
Biography: Wei Cui
Abstract
A multi-field coupling method based on virtual crack closure is proposed to detect weld crack propagation in X80 pipeline by magnetic flux leakage method, in order to analyze the interference effect of double cracks. Under the dynamic application of fluid pressure, crack initiation and propagation cause the change of weld structure of pipeline, and then affect the distribution of magnetic field in the surrounding computational domain. Every time the fluid pressure load is increased, the crack increment is completed, the crack geometry is updated, the grid is reconstructed, and the crack growth calculation and magnetic field analysis are carried out circularly. Taking the collinear double crack growth in the heat affected zone as a numerical simulation example, the finite element models of the single crack propagation in the outer wall of the pipe weld and the single crack propagation in the inner weld of the pipe are established respectively for comparative analysis. The results show that according to the characteristic values of fluid pressure, crack tip energy release rate, crack growth length, and peak value of magnetic induction intensity component, which are needed to describe crack growth in the propagation results, the process of crack growth is accelerated due to the interference effect of collinear double cracks. The realization of this method can provide technical reference for the fracture analysis of multi-crack long-distance oil and gas pipeline weld, and also provide a theoretical basis for the safety assessment of the weld seam with multiple cracks in oil and gas pipeline.