A coupled element modeling method is proposed for global dynamic analyses of unbonded flexible risers.
Owing to the multi-layer structure of unbonded flexible risers, the global-dynamic-analysis method applied to the
steel rigid risers is insufficient for flexible risers. The main challenges lie in the enormous difference between the
anti-tension and anti-binding capacity of unbonded flexible risers which results in serious ill-conditional calculation
in global dynamic analysis. In order to solve this problem, the coupled element modeling approach was proposed
in this study. A time domain fatigue analysis was applied to illustrate the necessity of the proposed approach.
A dynamic benchmark case is used to demonstrate the accuracy of the coupled element method respectively.
Subsequently the validated coupling element method is employed to conduct the global dynamic analyses for a
free hanging flexible riser. The results demonstrate that the proposed approach can give the accurate global
dynamic response under the guidance of the fatigue failure mode for unbonded flexible riser. The parametric
influence analyses also provide a practical and effective way for predicting the global dynamic response.
YANG He-zhen*(杨和振), JIANG Hao (姜豪), YANG Qi (杨启), DING Jin-hong (丁金鸿)
. Coupled Element Modeling Scheme for the Global Dynamic Analysis of Unbonded Flexible Risers[J]. Journal of Shanghai Jiaotong University(Science), 2015
, 20(2)
: 234
-242
.
DOI: 10.1007/s12204-015-1613-z
[1] Neto A G, Martins C A. A comparative wet collapse buckling study for the carcass layer of flexible pipes [J].Journal of Offshore Mechanics and Arctic Engineering of ASME, 2012, 134(3): 031701-031709.
[2] Nogueira V P P, Netto T A. A simple alternative method to estimate the collapse pressure of flexible pipes [C]//Proceedings of the 29th International Conference on Offshore Mechanics and Arctic Engineering.Shanghai, China: OMAE, 2010.
[3] Vaz M A, Rizzo N A S. A finite element model for flexible pipe armor wire instability [J]. Marine Structures,2011, 24(3): 275-291.
[4] Jiang Hao, Yang He-zhen, Liu Hao. Experimental and numerical analysis of a new simplified model for the deepwater unbonded flexible riser [J]. Chinese Journal of Ship Research, 2013, 8(1): 64-72 (in Chinese).
[5] Yang H Z, Li H J. Sensitivity analysis of fatigue life prediction for deepwater steel lazy wave catenary risers[J]. Science China Technological Sciences, 2011, 54(7):1881-1887.
[6] Ghadimi R. A simple and efficient algorithm for the static and dynamic analysis of flexible marine risers[J]. Computers & Structures, 1988, 29(4): 541-555.
[7] Chai Y T, Varyani K S, Barltrop N D P. Threedimensional lump-mass formulation of a catenary riser with bending, torsion and irregular seabed interaction effect [J]. Ocean Engineering, 2002, 29(12): 1503-1525.
[8] Chatjigeorgiou I K. A finite differences formulation for the linear and nonlinear dynamics of 2D catenary risers [J]. Ocean Engineering, 2008, 35(7): 616-636.
[9] McNamara J F, O’Brien P J, Gilroy S G. Nonlinear analysis of flexible risers using hybrid finite elements[J]. Journal of Offshore Mechanics and Arctic Engineering of ASME, 1988, 110(3): 197-204.
[10] Hosseini Kordkehili S A, Bahai H, Mirtaheri M. An updated Lagrangian finite element formulation for large displacement dynamic analysis of threedimensional flexible riser structures [J]. Ocean Engineering,2011, 38(5-6): 793-803.
[11] Saevik S, Berge S. Fatigue testing and theoretical studies of two 4 in flexible pipes [J]. Engineering Structures,1995, 17(4): 276-292.
[12] Yang H Z, Wang A J. Fatigue reliability based design optimization of bending stiffener [J]. Journal of Ship Research, 2012, 56(2): 120-128.
[13] Clarke T, Jacques R, Bisognin A, et al. Monitoring the structural integrity of a flexible riser during a full-scale fatigue test [J]. Engineering Structures, 2011,33(4): 1181-1186.
[14] Grealish F, Smith R, Zimmerman J. New industry guidelines for fatigue analysis of unbonded flexible risers [C]//Proceedings of the Offshore Technology Conference. Houston, USA: OTC, 2006.
[15] DNV-RP-C203, Fatigue design of offshore steel structures[S].
[16] Riggs H R, Leraand T. Efficient static analysis and design of flexible risers [J]. Journal of Offshore Mechanics and Arctic Engineering of ASME, 1991,113(3): 235-240.
[17] Yazdchi M, Crisfield M A. Non-linear dynamic behaviour of flexible marine pipes and risers [J]. International Journal for Numerical Methods in Engineering,2002, 54(9): 1265-1308.
[18] Larsen C M. Flexible riser analysis — Comparison of results from computer programs [J]. Marine Structures,1992, 5(2-3): 103-119.
[19] Wang A J, Yang H Z. Parametric influence analyses for umbilical installation in deepwater [J]. Journal of Ship Mechanics, 2012, 16(3): 226-235.
