考虑深海聚酯尼龙系泊缆的拉伸和弯曲变形,取正交坐标和切向量描述任意结点的6个广义位移,缆变形的几何非线性,基于细长杆理论推导缆索单元的刚度矩阵和质量矩阵,得到12×12的非线性单元特性矩阵,利用有限元软件计算系泊系统的动张力。针对水深1 800 m由12根缆定位的Spar平台,考虑水流对系泊系统的作用,计算了不同外激励下的系缆动张力,讨论了激励频率对系缆张力的影响。结果表明,建立的缆索单元特性矩阵可以较好模拟深海聚酯缆的力学性能,并且得到的深海系泊缆动张力变化规律和力学特性是合理的。
Based on the slender rod theory, the stiffness matrix and mass matrix of polyester cable dement in the deep seas are derived. In consideration of the extension and bending deformation of polyester cable, the 6 generalized displacements of the node are described in rectangular coordinate and its tangent vectors and a 12 × 12 nonlinear characteristic matrix are obtained by considering the geometric nonlinearity of the mooring hnes. Linking calculation program of user defined element and commercial software are developed, and the slender rod element can be called by general finite element software to calculate the dynamic tension of mooring system. The effects of fluid on mooring system are considered, the tensions of cable under different excitations are calculated, the effect of excitation frequency on cable tension is discussed for a spar platform with 12 mooring cables in 1800m water depth. The results show that the mechanical characteristics of polyester cable in deep seas can be well modeled by the characteristic matrix of cable, and the changing law and mechanical properties of dynamics tension reflected from the numerical result are reasonable for mooring cable in deep sea.