轴承不对中与轴承摩擦激励耦合作用下轴系的振动特性分析

Analysis of the Coupled Effect of Bearing Misalignment and Bearing Friction on Vibration Property of Shaft Systems

以船舶推进轴系为例,受低速、重载工作状态的影响,水润滑橡胶轴承可能处于边界或者混合润滑状态,相对较大的轴承摩擦激励力会对轴系的振动特性产生影响,甚至可能诱导异常振动和噪声。轴承基础沉降等因素会引起轴承标高变化,也会影响水润滑橡胶轴承支承界面摩擦激励力的分布,进而对推进轴系的横向、扭转振动特性产生影响。为了模拟边界或者混合润滑状态下橡胶轴承的刚度特性,将其简化成分布弹簧支承。在简化的基础上,建立推进轴系耦合振动动力学模型,利用模态叠加法对动力学方程进行降阶,并利用四阶Runge-Kutta方法进行动力响应分析,分析轴承标高变化对橡胶轴承摩擦力作用下轴系振动特性的影响。研究成果可为调节轴承标高以及识别轴系异常振动提供参考。

The water-lubricated rubber bearings of the propulsion shifting system of ships may work in the status of boundary lubrication or mixed lubrication especially under low-speed and high-load conditions,which will lead to non-negligible friction and induce abnormal noise and vibration and even squealing.The bearing foundation settlement can cause bearing misalignment and further influence the distribution of rubber bearing friction.As a result,these changes will take effect in transverse and torsional vibration properties of the propulsion shafting system.In this study,the stiffness characteristic of the rubber bearing under the mixed and boundary lubrication status is simulated.First of all,the rubber bearing is simplified to a set of distributed springs.Then,the dynamic model of the propulsion shafting system is built and the order-descent of the corresponding governing equation is carried out by means of the modal superposition method.The fourth order Runge-Kutta method is used to solve the differential equation for analyzing the dynamic responses of the shifting system.The influence of bearing misalignment on vibration property of the shifting system is analyzed.This study may provide a reference for regulating bearing elevation and identifying abnormal vibration of shifting systems.