A FE Model to Predict the Stress Concentration Factors in the Tensile Armor Wires of Flexible Pipes Inside End Fittings

Abstract

In this work, a bidimensional finite element (FE) approach is proposed to estimate the stresses induced in the tensile armor wires inside end fittings (EF) of flexible pipes. This approach accounts for the residual stresses caused by the mounting procedure and the deformed configuration of the wire. The resin and its interaction with the wires are also addressed. A parametric study was performed aiming at investigating the influence of three parameters on the stress state along the wire, i. e., the contact conditions between the resin and the wire inside the EF, the stress levels induced during the factory acceptance test (FAT) or the offshore leak test (OLT) and the resin elastic properties. The study pointed that high stress concentration is induced in the transition between the flexible pipe’s body and the EF and the stress distribution along the wire may be significantly affected by these parameters. Moreover, the apparent axial stiffness of the wire is also modified by its anchoring conditions, which may lead to non-uniform stress distributions among the wires of the tensile armor layers.