基于波分析法油膜刚度对轴系扭转振动影响的研究

为确保带减速齿轮箱主推进系统的可靠性，文章对船舶轴系的扭转振动进行了研究。首先根据各组成部件的特点将轴系分解为连续和离散的两个子系统，分别利用波分析法和多自由度系统分析法列出连续子系统的波动形式及离散子系统的振动微分方程，同时考虑了减速齿轮箱油膜刚度的影响。然后根据两子系统连接处的动态平衡和连续条件，建立整个轴系在扭转振动模式下总运动方程，通过求解总方程得到系统的位移响应。该扭转振动分析被应用到某LNG船带减速齿轮箱的轴系振动计算中，通过考虑轴系减速齿轮箱啮合齿面间油膜刚度使轴系扭转振动模型更接近轴系实际运转工况。计算结果显示：随着减速齿轮箱啮合齿面间油膜刚度的增加，最大轴系扭转应力向低转速区域偏移。这对船舶轴系转速禁区的划分产生极大的影响。有助于防止因不良轴系振动计算引起轴系事故的发生。

Research of Oil Film Stiffness Influence on Shafting Torsional Vibration Based on Wave Approach

Shafting vibration calculation is put out to ensure better reliability of main propulsion sys-tem with gearbox. The shafting system is modeled into continuous and discrete sub-systems, taking oil film stiffness of gearbox into consideration simultaneously. Wave approach and transit matrix method are used to investigate the displacement and stress fields in continuous and discrete sub-system re-spectively. And vibrations in different modes in both sub-systems are coupled by using dynamic e-quilibrium and continuity condition to deduce the global equations governing the motion of shafting. The torsional vibration calculation is then applied to research a certain LNG vessel with gearbox. It is shown that the vibration model with considered oil film stiffness is more reliable for the shaft-ing system with gearbox. The calculated results show that the max torsional stress appears in lower speed with oil film stiffness of gearbox ascending, and the barred-speed range is influenced greatly. This is helpful to prevent ship shafting accidents due to some poor shafting vibration calculation.