Global-Local Analysis of a Full-scale Composite Riser during Vortex-Induced Vibration

This paper presents a global-local analysis procedure to demonstrate the feasibility of a composite riser and its advantages over the traditional steel counterpart. This procedure starts from the local design of the sandwich tubular structure of riser section. The equivalent material properties of the sandwich tube are obtained using classic composite theory and they are used to parameterize the full-scale riser model in global analysis. The global analysis mainly focuses on the vortex-induced vibration (VIV). The methodology is first verified by comparison with experimental data and results produced by SHEAR 7. Four representative cases are then studied and the results show that the critical loads experienced by the composite riser are much lower than that of the steel one due to its lightweight. The lightweight composite riser requires lower top tension and fewer buoyancy cans, which is economically beneficial. The failure envelopes of both composite and steel riser sections are obtained by performing damage modelling techniques. The results show that composite riser yields larger safety margin. Overall, this paper demonstrates that composite riser is technically feasible and its high performance/weight ratio would make it a promising design for deepwater environment, where self-weight is a big challenge that is hindering the development of traditional steel riser.Copyright © 2013 by ASME