基于非线性度的滑动轴承-转子系统支承松动状态评估

Method for evaluating the pedestal looseness of the sliding bearingrotor system based on the non-linearity degree

基于振动信号非线性度建立了滑动轴承-转子系统支承松动状态评估方法。针对滑动轴承-转子系统支承松动故障,运用转子动力学、机械振动等理论分别建立转子系统存在支承松动故障与无故障时的非线性动力学模型,其中松动间隙产生垂直方向弹性力采用非线性项进行描述。根据非线性度的定义,对支承松动系统动力学模型中滑动轴承油膜力采用8个系数动态特性线性化,松动故障弹性力部分采用泰勒展开进行近似,得到线性近似系统动力学模型。比较存在支承松动转子系统动力学模型与线性近似动力学模型的动力学行为差异,结合MATLAB数值积分方法,计算在不同松动间隙大小情况下滑动轴承-转子系统动力学行为非线性度,建立非线性度与松动程度之间的关系,直观地反映出支承松动故障对滑动轴承-转子系统动力学行为的影响程度,为转子轴承系统的支承松动状态评估提供一种新的思路。

In this paper, an evaluation method based on the non-linearity degree of vibrating signals is proposed for the pedestal looseness of the sliding bearing-rotor system. The non-linear models for the sliding bearing - rotor system with and without pedestal looseness are established by means of such theories as rotor dynamics, mechanical vibration, and so on. The elastic force in the position of looseness fault is described by a non-linear term. In order to obtain the linear model for calculating the non-linear degree, the oil film force of sliding bearing in the non-linear dynamic model with pedestal looseness is linearized by means of eight dynamic coefficients, while the elastic force in the position of looseness fault is approximated by Taylor ex- pansion. The difference of dynamic behavior is compared between the non-linear models for the sliding beating-rotor system with and without pedestal looseness. The dynamic behavior non-linearity degree of the sliding bearing-rotor system under different loosening clearances is calculated by means of MATLAB numerical integration. The relationship between the non-linearity degree and the pedestal looseness is established, which will reflect the influence of pedestal looseness exerted on the dynamic behavior of the sliding bearing-rotor system and provide a new method for evaluating the pedestal looseness of the system.