Coupled fluid–structure simulations for evaluating a performance of full-scale deepwater composite riser. (15th January 2015)

• Record Type: Journal Article
• Authors: Tan, L.B.; Chen, Y.; Jaiman, Rajeev K.; Sun, X.; Tan, V.B.C.; Tay, T.E.
• Is Part Of: Ocean engineering. Volume 94(2015)
• Page Start: 19
• Page End: 35
• Publication Date: 2015-01-15
• Subjects: Carbon fiber reinforced polymer (CFRP) -- Vortex-induced vibration (VIV) -- Global–local analysis -- Composite riser -- Fluid–structure interaction (FSI) -- Failure envelopes; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2014.11.007
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: A global–local analysis methodology based on fluid–structure coupling is used to investigate the mechanical responses of both composite and steel risers. Since the design of the riser system can be a daunting task, involving hundreds of load cases for global analysis, semi-empirical fluid load models are considered for the reduced order computations of full-scale riser models. The structural performance of composite risers under real sea current conditions is investigated systematically and discussed with regard to the practical concerns in full-scale settings. The failure envelops of internal liners are found to be within that of the composite layers, which reveals that the liner is the weakest link for composite riser design. Results show that the composite risers can be more prone to vortex-induced vibration (VIV) due to their lower structural frequencies. In the present study, the composite riser yields 25.5% higher RMS strains than the steel riser. Placement of buoyancy modules along the riser may be critical for the design against VIV, and our results show that the modules are not recommended at the top region of the riser, especially if a top-sheared current is expected. Instead, it is preferable to implement them at the bottom-half portion of the riser and as a continuously buoyed region rather than short discrete buoys separated with gap spaces. Composite risers with different metallic liners are studied, and the titanium liner riser is found to be favourable over the steel and aluminum liner risers. Highlights: Global–local analysis is utilized to study steel and composite riser performances. The CFRP riser yielded 25.5% higher RMS strains than the steel riser. CFRP riser is more vulnerable to VIV due to lower structural frequencies. Buoys are not recommended at top of the riser if a top-sheared current is expected. Titanium is a good riser liner material candidate compared to steel and aluminum.