【作者】 崔立；

【导师】 王黎钦；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2008， 博士

【摘要】 滚动轴承作为航空发动机转子系统广泛采用的一种支承,其动态力学特性对转子系统的动力特性有重要的影响,随着航空发动机的性能不断提高,这种影响更为显著。因此,为了优化和提升现有发动机的动态性能,满足新一代先进航空发动机的研制需要,进行高速滚动轴承及其转子系统动态性能的研究十分必要。本文围绕航空发动机高速滚动轴承及其支承的转子系统,建立了滚动轴承的拟动力学分析模型、滚动轴承-转子系统的动特性和非线性振动模型,分析了不同工况参数和轴承结构参数对滚动轴承及转子系统动特性的影响,开发了分析程序,在现有的高速轴承台架上进行了高速轴承转子系统的验证实验。本文的研究为高速滚动轴承及其转子系统的分析提供理论基础,为航空发动机的可靠性分析提供技术储备。论文首先对高速滚动轴承的动态性能进行了研究,通过建立滚动轴承的拟动力学分析模型对高速球轴承和高速滚子轴承进行分析,工况和轴承结构参数对轴承动态性能有较大影响:球轴承的径向载荷和弯矩的存在会使滚动体的旋滚比、微区PV值、保持架滑动率等动态性能在数值上和变化规律上都有较大变化,且弯矩的影响更为明显。较小的接触角、较大的沟曲率对于降低球的PV值、降低保持架滑动率都有明显的影响。滚子轴承在高速轻载时,较小的弯矩就使滚子接触载荷峰值和PV值将变得很大,外圈存在椭圆度、具有较小径向游隙的滚子轴承对于降低滚子PV值、降低保持架滑动率都有明显的影响。研究了轴向预载荷对球轴承打滑的影响规律,给出了防止球轴承打滑的临界轴向载荷的定义:承受联合载荷作用或有弯矩存在的球轴承,当承载滚动体不打滑且保持架转速明显趋于平稳时对应的轴向载荷为临界轴向载荷;仅受轴向载荷作用的球轴承,滚动体打滑率为零时对应的轴向载荷为临界轴向载荷。并提供了在给定保持架滑动率下的轴承轴向预载荷。考虑轴承的动刚度用Riccati传递矩阵法分析了转子系统的动特性。与定刚度值计算相比,考虑动刚度对转子系统的临界转速、稳定性、失稳门槛值有较大的影响。转子系统的瞬态响应会影响支承轴承的动态性能,建立了滚动轴承与转子整体计算的模型,用Newmark-β积分法计算并分析了转子的响应和轴承的动态性能之间的耦合规律,发现当转子载荷变化速率较大、突加不平衡力较大时会引起转子的振幅较大,同时引起支承轴承保持架的滑动率也较大。为了揭示滚动轴承支承的转子系统的复杂振动特性,推导了滚动轴承的非线性轴承力,建立了滚动轴承非线性振动的运动微分方程,使用Runge-Kutta积分法求解。研究表明,滚动轴承的非线性轴承力会诱发变刚度振动,使系统响应中存在周期振动和拟周期、混沌非周期振动。选取适当的参数,轴承的接触角、游隙、预紧力、阻尼等,可以改善非线性轴承力引起的非周期振动行为。转子系统中存在不平衡力时,将使非周期振动区域明显增多,产生变刚度振动频率和不平衡力振动频率的组合振动。研究给出了滚动轴承外圈波纹度、内圈波纹度、滚动体波纹度引起的振动频率与轴承结构参数和波纹度阶数的关系。考虑转子的非线性振动发现在非周期振动范围内,滚动轴承的打滑率、刚度有较大变化。编制了滚动轴承设计与分析软件,使用软件集成技术实现了滚动轴承参数化设计、滚动轴承-转子系统性能预测、滚动轴承温度场分析和滚动轴承寿命预测的集成,为滚动轴承的设计与分析提供依据。使用经过实验验证的滚动轴承动力学算例对本文建立的滚动轴承拟动力学模型进行了验证,两者计算结果较为接近,对轴承稳态性能预测较准确,对于轴承瞬态运动学参数预测的误差在5%以内,表明本文建立的拟动力学模型可以较为准确的预测滚动轴承的动态性能。以现有的高速滚动轴承试验台架为基础,进行了高速滚动轴承转子系统动态性能的实验验证,测试了滚动轴承转子系统的临界转速、振动位移、轴心轨迹,与软件计算结果对比:理论计算结果与实验结果比较吻合,并揭示了转子系统中存在的复杂轴心轨迹,表明本文提出和建立的滚动轴承转子系统动态性能分析模型和方法可以较为精确和可靠的预测轴承和转子的动态性能。更多还原

【Abstract】 Rolling bearing is widely used as support in aero-engine rotor system, and its dynamic mechanical performances have important influence on the dynamic performances of the rotor system. The influence becomes more and more prominent with the enhancement of the performance of aero-engine. Therefore, in order to optimize and upgrade the existing aero-engine dynamic performance to meet the development needs of new generation aero-engine, it is necessary to study the dynamic performances of high-speed rolling bearings and rotor system. The objects of the research are high-speed rolling bearings and rotor system of aero-engine. The quasi-dynamic models of rolling bearing, dynamic property models of rolling bearing and rotor system, nonlinear vibration models of rolling bearing and rotor system are established. The influence of operating parameters and structure parameters of rolling bearing to the dynamic performances of rolling bearings and rotor system are analyzed. Computer programs are developed. High-speed rolling bearing and rotor system experiments are performed to validate the theory on an existing small high-speed rolling bearing bench. The research provides theoretical foundation for analysis of high-speed rolling bearings and rotor system, and also provides technical reserves for the reliability of aero-engine.The dynamic performances of high-speed rolling bearing are investigated. Through the analysis of high-speed ball bearing and roller bearing using the quasi-dynamic models, it is found that the operating parameters and structure parameters of rolling bearing have evident influence on the performances of the bearing. For the ball bearing with radial load and bending moment, spin to roll ratio, PV value of balls and sliding ratio of cage are changed greatly in value and rule when compared to axial loaded or radial loaded bearing, and the influences of bending moment are more evident. PV value of balls and sliding ratio of cage are decreased evidently by small contact angle or large groove curvature. For the roller bearing with bending moment, peak of contact load and PV value become large. Bending moments have significant influence on the dynamic performances of high-speed light-loaded roller bearing. PV value of rollers and sliding ratio of cage are decreased evidently by non-circular ring or small radial clearance. The influence rules of the axial pre-load to the skid of ball bearing are studied. The definition of the critical axial load to prevent skid of ball bearing is given. For the ball bearing with axial load and radial load or bending moment, the axial load is the critical axial load when there aren’t skidding in loaded balls and rotational speed of cage becomes stable. For the axial loaded ball bearing, the axial load is the critical axial load when loaded balls don’t skid. The axial load of ball bearing also can be provided when skid ratio of cage is given.The dynamic characteristics of the rotor system are analyzed considering dynamic stiffness of bearing using Riccati transfer matrix method. Compared to certain stiffness computation method, it is found that there are great influences on critical speed, stability, instability threshold of rotor system when dynamic stiffness of bearing are considered. For instantaneous response of rotor system can influence dynamic performances of rolling bearing, the whole computation model of bearing rotor system is established. The couple rules of rotor response and dynamic property of bearing are analyzed using Newmark-βmethod, it is found that amplitude of the rotor and cage sliding rate will becomes great larger when change ratio of load or sudden unbalance force is large.In order to reveal the complex vibration behavior of rotor system supported by rolling bearing, a nonlinear vibration analysis model is established and solved by Runge-Kutta method. The results show that the nonlinear variable stiffness vibration will be induced by nonlinear bearing force, which resulting in periodic vibration and quasi-periodic, chaos vibration in the system. Select appropriate parameters, such as, contact angle, clearance, preload of bearing and damping, etc., can improve the nonlinear vibration behavior caused by nonlinear bearing force. When unbalance force exist in the rotor system, non-periodic vibration regions will increase and combined vibration constitute of variable stiffness vibration frequency and unbalance vibration frequency will occur. The relationship between vibration frequency caused by outer waviness, inner waviness, rolling element waviness of bearing and bearing structure parameters, waviness orders is given. Considering nonlinear vibration of rotor system, it is found that skid ratio and stiffness of bearing are changed greatly.A design and analysis software for rolling bearing has been developed using software integration technology. The software integrates parametric design of bearing, performance prediction of bearing rotor system, temperature field analysis and life prediction of bearing, which provide method for design and analysis of rolling bearing.The quasi-dynamic model of rolling bearing is validated by dynamic example which has been validated by test. The results in this dissertation are very close to the example and the difference is less than 5%, which shows that the model and method put forward in the dissertation to forecast the bearing characteristics is precise.At last, dynamic characteristics test researches of high-speed rolling bearing rotor system have been finished using the rolling bearing bench test. Critical speed, vibration displacement, axis orbit are obtained. The theoretical results in this dissertation are very close to test data and disclose the complex axis orbit of the rotor system, which shows that the model and method put forward in the dissertation to forecast dynamic property of rolling bearing rotor system is precise and credible.更多还原