Supercritical CO2 pipeline is the main way to transport carbon dioxide. However, due to the decompression wave characteristics of supercritical CO2, once the pipeline cracked, it will lead to the continuous propagation of cracks, which threatens the safety of pipeline operation. To study the crack propagation mechanism of supercritical CO2 pipeline, the instrumented impact test is carried out, and the parameters of Cohesive Zone Model are calibrated by inversion the test results. By comparing the trapezoidal traction separation law and linear traction separation law, it is found that the simulation results of the trapezoidal constitutive are in good agreement with the experimental results, and a more accurate material model of the crack propagation region is obtained. Based on the Cohesive Zone Model, the finite element model of crack propagation in supercritical CO2 pipeline is established to analyze the effects of pressure, wall thickness, pipe diameter on the crack propagation velocity. The results show that for supercritical CO2 pipeline, under the given gas composition, pressure and temperature conditions, with the increase of internal pressure, the decrease of wall thickness and the increase of pipe diameter, the crack arrest pressure of pipeline decreases. It is necessary to improve the crack arrest toughness of pipeline to ensure that the pipeline can achieve crack arrest within a limited length. The research results can provide a theoretical basis for crack propagation of supercritical CO2 pipeline and have practical engineering reference significance.
Keywords Supercritical CO2 pipeline, instrumented impact test, Cohesive Zone Model, crack propagation velocity