三芯光纤复合海底电缆船锚钩挂有限元建模

Finite Element Modeling of Anchor Hooking of Three-Core Optical Fiber Composed Submarine Power Cable

为了利用分布式光纤传感技术测量的光纤应变反映三芯光纤复合海底电缆被船锚钩挂时机械特性失效与否,利用有限元方法建立了钩挂的有限元模型。忽略机械特性差的结构,将聚乙烯护套与填充层合并以增大填充层边缘尺寸,获得均匀的网格;将呈对称分布的光单元简化为一根,得到简化后的海缆模型。选用SOLID164单元作为海缆结构的单元类型,选用BKIN(双线性随动强化)材料作为海缆结构的材料模型,得到海缆的有限元模型。最后通过仿真分析获得铜导体的应力分布情况、光单元的应变情况以及铜导体塑性应变和光单元应变随时间变化的情况。结果表明,海缆与锚接触位置处的铜导体应力值较未接触的位置应力值偏大,并且获得了铜导体发生塑性应变时的光单元应变值,该值可作为海缆导体机械特性失效的判据。

Whether the mechanical characteristics of the three core optical fiber composite submarine cable are still effective or not when the hook is hanged can be reflected by the optical fiber strain measured by using the distributed optical fiber sensing technology. Therefore in this paper, a finite element model for the hook is set up. The structures with little protective effect and poor mechanical properties are ignored for their limited impacts on the anchor. Combining the polyethylene sheath with filling layer to increase the size of the edge of the filling layer, the uniform mesh can be ob- tained. Symmetrically distributed light units are reasonably simplified to one unit. Thus, a simplified submarine cable model is obtained. A SOLID164 unit is chosen as the unit type of submarine cable, and BKIN （ bilinear follower fortifi- cation） material is selected as the material model of sea cable structure. Consequently, the finite element model of sub- marine cable is obtained. Finally, the stress distribution of the copper conductor, strain condition of the light element, plastic strain-time of the normalized copper conductor and the strain-time of thenormalized light element are obtained by simulation. The results show that the stress value of the copper conductor at the contact point between the cable and the anchor is larger than that of the untouched position, and the strain value of the light unit in the plastic strain of the copper conductor is calculated. This value can be considered as a criterion for the failure of the mechanical properties of the cable for the detection of submarine cable.