Objective Pipelines serve as the primary transportation means for Carbon Capture, Utilization and Storage (CCUS) technology, so it is vital to study their dynamic fracture propagation laws. However, the prolonged preparation periods, technical complexities, substantial financial investments, and numerous uncertain factors associated with full-scale fracture experiments significantly impede progress in studying pipeline fracture and the internal decompression laws during CO₂ transmission pipeline fracture propagation.

Methods Leveraging bidirectional Fluid-Structure-Interaction (FSI) technology, a user-defined subprogram was developed with Frotran to delineate fluid decompression characteristics. A Gurson-Tvergarrd-Needleman (GTN) constitutive equation for pipes was established through an experiment focusing on material properties. Moreover, a fluid-structure interaction numerical model was constructed in ABAQUS/Explicit software to simulate supercritical dynamic crack propagation and internal decompression of CO₂ transmission pipelines. This model was subsequently used for a collaborative analysis of pipeline crack propagation characteristics and internal medium decompression laws. The simulation results were further processed in batches through Python scripts.

Results The pipeline fracture morphology from numerical simulation closely mirrored the experimental results. The crack propagation velocity showed an initial rapid increase after medium spillage, followed by gradual stabilization, and finally reaching approximately 225 m/s. The crack tip opening angles initially decreased, then increased before stabilizing at around 7.22°.CO₂ remained under high pressure near the crack propagation tip, while saturated steam formed through decompressional expansion at the crack tip worked against crack arrest.

Conclusion This study demonstrates the accurate replication of full-scale fracture experiments by simulation and showcases the advantages of simulation in revealing many parameters that can hardly be captured through experiments, such as crack tip opening angles, as well as pressure evolution at crack tips and fracture zones during pipeline fractures. The constructed numerical model of CO₂ fluid-structure interactions facilitates an in-depth analysis of CO₂ transmission pipeline fracture qualities. The simulation results can serve as references for safety control assessments of CO₂ pipelines with varying dimensions and gas parameters.