Bending capacity of sandwich pipes

A sandwich pipe (SP) is an effective design alternative, providing effective load carrying capacity and thermal insulation to pipelines, especially when the pipe is going to be utilized in deep and ultra-deep water applications. However, the design and development of a reliable SP requires an in-depth understanding of the behavior of such a system under various loading conditions. In this paper, the behavior of SPs subject to pure bending, which is one of the governing loading conditions for offshore pipelines, is investigated.In order to perform this investigation, a series of numerical parametric models, using the finite element (FE) method, was developed. The linear eigenvalue buckling analysis and the nonlinear post-buckling analysis were conducted to explore the systems' response. The influence of several significant structural parameters on the pre-buckling, buckling and post-buckling responses of SPs was investigated. The parameters investigated included various combinations of several geometrical and material properties, as well as the consideration of various possible intra-layer adhesion mechanisms. Moreover, the recent high strength steels used in formation of oil and pipes exhibit certain degree of yield anisotropy; it is therefore crucial to understand the effect of material's yield anisotropy on such system's response. This issue has also been considered in this research.