Fluid-structure-fracture coupling 1D model for unstable ductile fracture in high-pressure gas pipelines -development of model (1st report)-

Abstract

Prevention of unstable ductile crack propagation is one of crucial issues in pipeline industry. Unstable ductile crack propagation in pipelines is complex coupling phenomenon among gas decompression inside pipelines, pipe deformation and crack propagation. Therefore, numerical methods are highly valuable for safety design against unstable ductile crack propagation. In this study, uid-structure-fracture coupling 1D model for unstable ductile fracture in high-pressure gas pipelines was developed. The model describes gas decompression and pipe deformation by 1D partial differential equations, and judges whether or not a crack propagates using dynamic energy balance. Effect of soil backfill which constrains pipe deformation is formulated as added mass on a pipe wall. Because 1D partial differential equations in the model is solved by finite difference method, the model consumes lower CPU cost as compared to 3D finite element based model. Therefore, the model has a potential as a tool of pipeline design.