The installation of a subsea production tree based on a variable-length cable finite element model

The current paper applies a variable-length cable FEM based on the absolute nodal coordinate formulation with the arbitrary Lagrangian-Eulerian description to simulate the installation process of a subsea production tree (SPT). The material coordinate is employed together with the global position and position gradients as the state variable. In addition, the movingmesh technology is applied to simulate the deployment of the cable. Two types of elements, including the constant-length and variable-length elements, are defined based on the variation of the material coordinates of the elements. Firstly, the equations of motion of the variable-length cable subjected to the complex environmental loads are derived based on the generalized D'Alembert principle. Second, the obtained differential-algebraic equations are numerically solved by the Backward Euler scheme and a Newton-Raphson iteration solver. Third, the implemented model is validated for both the static and dynamic simulation by comparing the results of the commercial software ProteusDS. Finally, a detailed parametric study is conducted to investigate the deployment behaviour of the subsea production tree under complex environmental loads.