Numerical Investigation of High-Speed Dynamic Fractures and Crack Arresting of High-Grade Gas Pipelines

The fracture speed of a high-grade gas pipeline subjected to high gas pressure is usually very high, such that the gas pressure near the crack-tip could not decompress rapidly. It is difficult for a high-grade pipeline to arrest crack propagation by itself; hence, an arrestor should be installed to prevent the pipeline from fracturing continuously. Because the optimization of the geometric size of the arrestor has not been well-recognized at present, it is of interest to study the dependence of crack arresting ability on arrestor size and obtain a satisfactory method to design the geometric size of the arrestor. Based on Hill’s yield theory and a plastic strain–dependent damage evolution law, a transversely isotropic elastic-plastic damage model is established. The mechanical responses of X80 pipeline material under static and dynamic loadings were successfully simulated by the proposed constitutive law. Using the cohesive zone model, the high-speed dynamic fracture and crack arresting ability of the X80 gas pipeline were simulated. The dependences of crack arresting ability on the thickness and length of the arrestor were numerically investigated. The simulation results showed that the crack arresting performance increases significantly with the thickness of the arrestor. The satisfactory geometrical size of an arrestor is economically suggested.