Using Axisymmetric Smoothed Finite Element Method (S-FEM) to Analyze Pressure Piping with Defect in ABAQUS

Pressure piping is the most productive way for large-volume compressed natural gas (CNG) transportation. In pipeline constructions, the thickness at the point where two pipes join together is often not consistent due to the mismatch in dimensions, and thus stress concentrations can often occur at the pipe joints, causing safety concerns. Therefore, it is important to accurately analyze the key influencing factors of dimensional mismatch defects, providing a theoretical basis for the preliminary design and post-repair of pipelines. This work uses the smoothed finite element method (S-FEM) that has been proven accurate in stress analysis compared with the traditional FEM. Since geometry and load of the pressure piping are axisymmetric, a novel axisymmetric S-FEM element is first developed, coded and integrated in ABAQUS using the User-defined Element Library (UEL). Intensive studies are then carried out. to examine the effects of different. levels of mismatch in the thicknesses of two joined pipes and the effects of the radius of the transitional fillet used to bridge the mismatches. It is found that the maximum hoop stress reduces as the radius of the transitional fillet increases. For the thinner section of the pipe, the maximum hoop stress is only affected by the thickness mismatch.