舰船科学技术  2019, Vol. 41 Issue (10): 120-123 PDF

Multiple degrees of freedom motion characteristics analysis for tower soft yoke single mooring system based on ADAMS
HU Yong, LI Hui, ZHU Gang, LI Lei, LI Guang
Wuhan Second Ship Design and Research Institute, Wuhan 430064, China
Abstract: This paper makes a research on the coupled motion between Tower Soft Yoke Single Mooring System and ship, predictive analysis on multiple degrees of freedom motion characteristics for Soft Yoke Mooring System based on ADAMS. The results revealed that when ship moved transverse, the variation trend of Soft Yoke System stiffness is similar with lengthwise. The magnitude of stiffness is smaller than lengthwise under the same displacement. The attitude of two pendants is different as the increase of ship motion displacement. The left pendant gradually turned up after Yoke revolved on its own axis. The tension of pendant was larger than right one. Yoke collided with ship from the ship collision analysis when ship is 8.19 m near jacket. The collision force reached 8 251 N. This is beneficial for Single Mooring System optimization.
Key words: single mooring system     soft yoke     pendant     stiffness     collision
0 引　言

1 软刚臂系泊系统

 图 1 软刚臂单点系泊系统示意图 Fig. 1 Schematic diagram of the soft-arm single-point mooring system

2 纵向运动时软刚臂系统刚度理论计算

 图 2 软刚臂单点系泊系统的几何关系与受力 Fig. 2 Geometric relationship and force of the soft-arm single-point mooring system

 ${F_{AX}} = {F_{CX}}\text{，}$ (1)

 ${F_{AZ}} + {F_{CZ}} = {W_1} + {W_2} + {W_3}\text{，}$ (2)

 $\begin{gathered} {F_{CZ}} \times {L_3} \times \sin \beta = {F_{CX}} \times {L_3} \times \cos \beta+ \\ {W_3} \times \frac{{{L_3}}}{2} \times \sin \beta \text{，} \\ \end{gathered}$ (3)

 $\begin{split} {W_1} \times {L_1} \times \cos (\alpha + \beta ) + {W_2} \times {L_2} \times \cos (\alpha + \beta ) + \\ {W_3}\left(\sqrt {L_4^2 + L_5^2} cos\alpha + \frac{{{L_3}}}{2}sin\beta \right) =\quad\quad\\ {F_{CZ}}\left(\sqrt {L_4^2 + L_5^2} cos\alpha + {L_3} \times \sin \beta \right) - {F_{CX}}({H_2} - {H_1}) \text{。} \\ \end{split}$ (4)

 ${F_{CX}} = \left({F_{CZ}} - \frac{{{W_3}}}{2}\right){\rm{tan}}\beta \text{，}$ (5)

 ${L_0} = \sqrt {L_4^2 + L_5^2 - {{({L_3} - H)}^2}} \text{，}$ (6)

 $X = \sqrt {L_4^2 + L_5^2} \cos \theta + {L_3}\sin \beta - {L_0}\text{。}$ (7)

 ${F_{CX}} = \frac{{({W_1}{L_1} + {W_2}{L_2})cos(\beta + \theta ) + \frac{{{W_3}}}{2}\sqrt {L_4^2 + L_5^2} \cos \theta }}{{\frac{{\sqrt {L_4^2 + L_5^2} \cos \theta }}{{\tan \beta }} + {L_3}\cos \beta - H}}\text{。}$ (8)

 $K = \frac{{{F_{CX}}}}{X}\text{。}$ (9)
3 纵向运动时软刚臂系统刚度验证

 图 4 船体纵向运动刚度曲线 Fig. 4 Longitudinal motion stiffness curve of hull

 图 5 船体纵向运动时塔台作用力及系泊腿张力 Fig. 5 Tower force and mooring leg tension during longitudinal movement of the hull
4 船体横向运动时软刚臂系统分析 4.1 横向运动刚度曲线

 图 6 船体横向运动刚度曲线 Fig. 6 Hull lateral motion stiffness curve
4.2 横向运动系泊腿张力和塔台作用力

 图 7 船体横向运动时塔台作用力及系泊腿张力 Fig. 7 Tower force and mooring leg tension when the hull is moving laterally
4.3 软刚臂系统角度变化

 图 8 船体横向运动时软刚臂角度变化 Fig. 8 Angle change of soft rigid arm when the hull moves laterally
4.4 软刚臂系统与船体甲板的碰撞

 图 9 船体纵向运动靠近导管架时与软刚臂碰撞分析 Fig. 9 Collision analysis between the soft rigid arm and the jacket when the longitudinal movement of the hull

5 结　语

1）船体横向运动时，软刚臂系统的刚度呈递增的趋势，和纵向运动时一致，当横向运动Y=10 m时，FY=81.17 t，数值上小于相同位移的纵向运动刚度。2条系泊腿的恢复力也不相同，沿正方向运动时，左系泊腿的恢复力接近为右系泊腿恢复力的2倍。

2）横向运动系泊腿张力和塔台作用力与纵向运动时也不相同，主要由于随着船体正向运动位移的增加，2条系泊腿的姿态逐渐不相同，左系泊腿随着软刚臂自转，出现向上翘起，张力大于右系泊腿。

3）当船体横向运动时，软刚臂系统绕导管架中心轴线的转角变化、横摇角和纵摇角度也发生一定的变化，软刚臂自转角度变大，增大至22.3°后趋于稳定，说明船体运动接近极限位置，纵摇角度值较小，最大为1.5°。

4）通过碰撞分析发现，当船体靠近导管架8.19 m时，软刚臂与船首甲板发生碰撞，其碰撞力达到8 251 N，当碰撞造成材料塑性变形或者破坏时，其碰撞力会逐渐变小，这有利于单点系泊系统前期设计的优化。

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