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Umbilical cables are composite structures that consisting of metallic material and polymeric material. Analysing tension behaviour under axial loading is a key requirement to design the structure. A full three-dimensional finite element model is established in which the effect of radial deformation is given more attention. A plane finite element analysis is proposed to predict the radial stiffness of the inner core with several components. The tension behaviour of an umbilical cable is analysed by the proposed models. Tension tests of the umbilical cable were carried out. Compared with the available theoretical models in the literature, the finite element model has a satisfactory agreement with the experimental results. In addition, the finite element model is used for the assessment of the influence of the important parameters on the tension behaviour, which is helpful for the design of umbilical cable.

The flexible cryogenic hose has been a favored alternative for offshore liquefied natural gas (LNG) exploitation recently, of which helical corrugated steel pipe is the crucial component with C shaped corrugation. Parametric finite-element models of LNG cryogenic helical corrugated pipe are presented based on 3D shell element in this paper. Taking account of nonlinearity such as cryogenic material and large geometric structural deformation, mechanical behavior characteristics results are obtained under axial tensional, bending and inner pressure loads. Meanwhile, the design parameters are determined for the shape optimization of structures of the flexible cryogenic hose through sectional dimension analysis, and sensitivity analysis is performed with changing geometric parameters. A multi-objective optimization with the object of minimizing stiffness and strength stress is formulated based on operation condition. Full factorial experiment and radial basis function (RBF) neural network are applied to establish the approximated model for the analysis of the structure. The Pareto optimal solution set and value range of parameters are obtained through NSGA-II GA algorithm under manufacturing and stiffness constraints. It provides a feasible optimal approach for the structural design of LNG cryogenic corrugated hose.