Numerical Simulation of Damage and Repair Resulting from a Lateral Denting in a Pipe Caused by a Indenter
This paper describes the initial stage of a tool project, designed for structural repairs of pipes that have been dented by an external contact. The objective of this study is to qualify a numerical procedure for damage assessment of smooth plain denting in pipes through comparisons with experimental results, and to allow a simulation of its behavior while subjected to a diameter restoration tool. In this work three pipeline geometries, under “plain” dents, are considered. The applied loads consisted of a prescribing the radial displacement of an indenter, having a maximum value of 15% of the pipe nominal diameter. Afterwards a restoring of the pipe cross-section shape was simulated leaving a residual indentation, equivalent to 5% of the pipe initial diameter. Material and geometric nonlinearity capabilities were activated in the finite element analyses using ANSYS, version 6.1, finite element program. Due to symmetry only one half of the structure needed to be modeled. The considered pipe, with 5m in length, was classified as an API 5L-B and API X-65 and was simulated using three element formulations: SHELL 43, TARGE 174 and CONTA 170. The last two were used to represent contact conditions between the indenter and the pipe surface. The analyses were set to include the following kinematics and material phenomena: large displacements, large strains, plasticity, stress-stiffening, and contact. From this study it was possible to assist the experiments in the specification of the necessary loading paths to indent the pipes and to restore its cross-section roundness as well as to define the right parameters for an accurate evaluation of the pipe behavior.