Stability and post-buckling response of sandwich pipes under hydrostatic external pressure

Sandwich pipe systems can be considered as potentially optimum design configurations for overcoming the shortfalls of single-walled pipes for deep-water applications. This potential design alternative has gained considerable attention in recent years. In this paper the stability of these systems is investigated. The possible equilibrium paths are evaluated and the effect of the various significant parameters on the characteristic behavior of the system is discussed. The Finite Element (FE) software package ABAQUS is used to construct more than 3000 FE models of the sandwich pipes with practical configurations. Four design configurations are considered for the sandwich pipes with respect to the adhesion among the interfaces. The post-buckling behavior of each of these configurations is determined, with emphasis on a wide practical range of parameters. The behavior of these configurations is examined and the efficiency of each system is discussed. Finally, a simplified and fairly accurate equation is developed and recommended for calculating the pressure capacity of sandwich pipes. The parameters of the proposed equation are also fully defined.

► The stability of sandwich pipes (SP) in deep water is investigated.
► 3000 FE models of SP with practical configurations were constructed and analyzed.
► The possible equilibrium paths are evaluated and the effect of the various significant parameters is discussed.
► The interface core/pipe adhesion is also investigated and shown to have significant impact on the stability.
► Finally, a simplified and fairly accurate equation is developed for calculating the pressure capacity of SP.