钢管脐带缆扭转平衡设计

钢管脐带缆包含多种螺旋缠绕的功能单元，其在外力载荷下会发生相对运动，而且钢管的刚度较大对扭转平衡有重要影响，因此，相对于普通电缆，钢管脐带缆在扭转平衡设计时更加困难。根据扭转平衡理论公式，采用控制变量法，以第二层铠装钢丝的绞合角度为变量进行扭转平衡设计。首先建立脐带缆缆芯有限元模型，对其施加拉伸载荷，结果显示缆芯出现了扭转，这证明不能将脐带缆缆芯视为一实心圆柱。其次建立不同绞合角度的脐带缆有限元模型，设置各功能单元的材料属性和摩擦系数，分析模型在拉伸载荷下的扭转角度，并将相同拉伸载荷下的扭转角度拟合为直线，从而得到钢管脐带缆在扭转平衡状态时的最优绞合角度。最后，采用试验方法对实物钢管脐带缆进行扭转平衡测试，测试结果显示在拉伸载荷下脐带缆单位长度扭转角度十分微小，这表明缆是扭转平衡的。因此验证了使用的有限元方法在钢管脐带缆扭转平衡设计中的有效性。

Torque balance design of steel tube umbilical cable

The steel tube umbilical cable consists of various helical stranded functional elements that will move relatively under external load, meanwhile, the rigidity of the steel tubes that have an important effect on torque balance is high, therefore the torque balance design of the steel tube umbilical cable is difficult compared with that of ordinary power cable. Based on the torque balance theoretical formula, the control variable method that the strand angles of second armor wires are selected as the variable is applied in the torque balance design. First, a umbilical core FE model is built, and the model rotates when tension load is applied. The result indicates that the umbilical core can not be treated as a solid core. Secondly, umbilical cable FE models with different stranded angles are built, and detailed material properties and friction factors of functional elements are considered to analyze the models'' rotation angle under tension load. The rotation angles under the same tension load are fitted to a straight line, so that the optimum stranded angle is determined when umbilical cable is in torque balance condition. Finally, experimental tests are performed on the steel tube umbilical cable. The test result shows the rotation angles per unit length of umbilical cable are negligible under tension load, proving the umbilical cable is torque-balanced. The test result verifies the validity of the introduced FE method in the torque balance design of steel tube umbilical cable.