Journal of Shanghai Jiaotong University ›› 2018, Vol. 52 ›› Issue (9): 1017-1022.doi: 10.16183/j.cnki.jsjtu.2018.09.002

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Lateral Failure Analysis of Unbonded Flexible Risers Under Axial Compression Force

LIU Xiaoyuan,XUE Hongxiang,TANG Wenyong   

  1. State Key Laboratory of Ocean Engineering; Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai Jiao Tong University, Shanghai 200240, China

Abstract: Nonlinear finite element method is used to study the failure characters of flexible riser under axial compression force. The tensile armor layer, structural tape and outer sheath are modeled by solid elements. Material nonlinearity, geometrical large deformation, complex contact and friction are considered in this article. The effects of number of helix bands in armor layer, friction coefficient, thickness of outer sheath on the failure modes and axial compression force of flexible risers are studied. The results show that the failure process of all steel helix bands model is more complex than the simplified model which only contains partial helix bands. And the axial compression force exhibits a multiple peak phenomenon. Friction coefficient has a great influence on failure mode. It’s a lateral failure when the friction coefficient is small, otherwise a radial failure when the friction coefficient is large. The thickness of the outer sheath has limited influence on the maximum axial compression force of lateral failure.

Key words: unbonded flexible risers, axial compression force, lateral failure, nonlinear finite element method

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