Research progress on dynamic crack propagation and crack arrest models of supercritical and dense-phase CO2 pipelines

In the past decade, research on the propagation and arrest of CO 2 pipeline fractures has achieved some results. This paper comprehensively reviews and evaluates the full-scale burst test, theoretical model of arrest toughness, and numerical simulation, and systematically analyzes the remaining problems. Among them, the brittle-ductile transition process during the fracture process of the pipeline is still unclear, and the relationship between the crack tip pressure and the saturation pressure is still debatable. Both of these points need to be further studied through experiments. Furthermore, the scarcity of existing experimental data has limited the applicability of current arrest models. The prediction of low toughness or saturation pressure is overly conservative, and the experimental-based arrest theory model requires further refinement and optimization. In terms of numerical models, finite element simulation's accuracy in predicting the fracture process requires improvement, while the fluid-solid coupling model improves calculation accuracy. However, due to the limitations of existing commercial software for calculating the FSI problem, there is a need to develop a commercial FSI strategy for CO 2 pipeline crack propagation. In addition, the majority of existing models describe fluid behavior using homogeneous flow models, and there have been few studies on decompression models that account for delayed phase changes, limiting the model's prediction accuracy. The three-dimensional pipe-fluid-soil coupling is the most complete model for calculating fracture processes, and it should be the primary focus and challenge of numerical simulation.