This paper presents a numerical method to predict the behavior of unbonded flexible risers under symmetrical loads, and takes an eight-layer unbonded flexible riser for the case study. In order to accurately simulate geometric properties of the riser and contact interaction between layers, carcass and zeta layers are modeled as the actual complicated cross-sections, and all layers are modeled by solid element, both contact and friction between layers are taken into consideration. ABAQUS/Explicit is adopted to avoid convergence problem caused by geometric and contact nonlinearities, mass scaling is adopted to avoid long computational time caused by the very detailed finite element model of carcass and zeta layers. Load cases considered in this paper are external pressure coupled with axial tension, axial compression under different lay angles of helical strips and boundary conditions. The results show that numerical results agree well with theoretical results, lay angles of tensile armor layers have a great impact on the axial displacement, but boundary conditions have little effect on the axial displacement.

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