Finite-element simulation of flexible pipe mechanical response: challenges and solutions

• Published in: Journal of pipeline engineering 2015-12, Vol.14 (4)
• Main Authors: Ebrahimi, Alireza, Kenny, Shawn, Hussein, Amgad
• Format: Article
• Language: English
• Subjects: Buckling; Finite element method; Mathematical analysis; Mathematical models; Mechanical analysis; Petroleum pipelines; Pipe; Public domain
• ISSN: 1753-2116

FLEXIBLE PIPELINES HAVE FOUND application in the offshore oil and gas industry due to inherent characteristics that includes low bending stiffness (i.e., flexibility), high axial strength, and resistance to collapse, fatigue, and abrasion. These performance attributes are related to the unique features of the flexible pipe manufacturing processes that produce a composite pipe section through the integration of various material components including steel and polymeric layers. Each layer has a specific role to meet a functional design requirement and the composite section can be tailored to meet project-specific needs. The composite section may exhibit a complex mechanical response with respect to deformation mechanisms and local instability (such as radial or lateral buckling), fatigue, and material degradation or creep. There are a limited number of analytical solutions and numerical models addressing the mechanical behaviour of flexible pipe. These studies were constrained by idealizations and simplifications in order to attain tractable solutions. Even fewer experimental modelling tests are available in the public domain to support these studies. Consequently, the development of a more-robust computational model examining the mechanical response of flexible pipe was conducted. In this study, continuum- finite-element modelling procedures were verified, using the limited available public-domain information and data, for a flexible pipe subject to combined loading of axial compression with external and internal hydrostatic pressure. The potential for local, radial buckling instability (i.e. the 'birdcaging' failure mechanism) was also examined. The challenges, constraints, uncertainties, and proposed solutions to successfully model the complex interaction between multiple composite layers are discussed. The outcomes from this study also provide guidance on the development and verification of these numerical simulation procedures where there limited guidance presently exists in the public domain.