故障转子弯曲及其弯—扭耦合振动特性的研究

发布时间：2018-12-07 19:24

【摘要】：现代生产中,旋转机械日益高速化、重载化、自动化以及功能多样化,转子系统作为旋转机械的关键部件,时常会出现许多问题。运行环境的恶劣以及设备安装过程中存在的误差都将激发起各种复杂非线性因素作用,引发旋转机械激烈的振动。比如,因运动部件与静止部件发生碰摩故障而产生的振动。碰摩故障通常为其它故障的间接结果。振动原因可能是由转子质量不平衡、轴系失稳、机组中心不对中或者热膨胀等引起。系统一旦发生碰摩,转子零部件很可能会由于扭转疲劳或者其他过多的弯曲运动引起破坏。轻则影响工作效率,重则机毁人亡。而不平衡故障常常潜伏在机组中,其极易引发恶性的振动事故。这些事故所造成的人员伤亡、社会危害和经济损失都是不可估量的。较为复杂的机组振动特性研究是不适宜采用简单的模型。因此,应用现代数值分析理论和转子动力学理论来研究复合故障的转子系统建模、求解以及弯-扭耦合振动特性,已成为当今国内外的热门研究课题之一。本文通过对单故障和复合故障的转子系统弯-扭耦合振动特性逐步进行了研究,并建立了4个转子系统模型。第一步,考虑滚动轴承的滚动体与内外圈之间的非线性赫兹接触力,建立了一个基于滚动轴承支承的质量不平衡转子动力学模型；第二步,针对两端刚性支承的单圆盘转子,建立了碰摩转子模型；第三步,将不平衡转子系统置于两种工况下,即一种在外激励力作用下,另一种在外激励扭矩作用下,分别建立相应的转子系统弯-扭耦合振动模型；第四步,建立了一个不平衡故障和碰摩故障复合作用下的转子系统有限元模型。对于这4个模型,本文采用了两种数值分析法来求解系统的响应,他们分别是四阶龙格库塔法和纽马克-β法。利用位移图(振动波形图)、瞬时频率图、包络图、载波图、相图、轴心轨迹图、庞加莱映射图分析了各个转子系统在特定参数下的运动特征,通过上面的相关图形分析了转子系统随若干参数(转速、转子质量、轴承等效质量、偏心距、转轴等效刚度等)变化时系统的响应,以及耦合故障下的振动特性。为不同工况下的故障诊断奠定了一定的理论基础。
[Abstract]:In modern production, rotating machinery is becoming more and more high speed, heavy load, automation and diversified functions. As a key component of rotating machinery, many problems often arise. The bad running environment and the errors in the installation of the equipment will excite all kinds of complex nonlinear factors and cause the violent vibration of the rotating machinery. For example, vibration caused by rub-impact failure of moving parts and stationary parts. Rub-impact faults are usually indirect results of other faults. Vibration may be caused by rotor mass imbalance, shafting instability, unit center misalignment or thermal expansion. Once the system is rubbed, rotor parts may be damaged by torsional fatigue or other excessive bending motion. Light will affect the efficiency of work, heavy damage to the machine death. But the unbalanced fault often lurks in the unit, it is easy to cause the malignant vibration accident. The casualties, social harm and economic losses caused by these accidents are incalculable. It is not suitable to use a simple model to study the vibration characteristics of complex units. Therefore, the application of modern numerical analysis theory and rotor dynamics theory to study the rotor system modeling, solving and bending torsional coupling vibration characteristics of complex faults has become one of the hot research topics at home and abroad. In this paper, the bending-torsional coupling vibration characteristics of rotor system with single and complex faults are studied step by step, and four rotor system models are established. In the first step, considering the nonlinear Hertz contact force between the rolling body and the inner and outer ring of the rolling bearing, a mass unbalance rotor dynamic model based on the rolling bearing support is established. In the second step, the rub-impact rotor model is established for the single-disk rotor with rigid supports at both ends. In the third step, the unbalance rotor system is put into two working conditions, that is, under one kind of external excitation force and the other kind of external excitation torque, the corresponding bending-torsional coupling vibration model of the rotor system is established respectively. In the fourth step, a finite element model of rotor system under the combined action of unbalanced fault and rub-impact fault is established. For these four models, two kinds of numerical analysis methods are used to solve the response of the system. They are the fourth order Runge-Kutta method and the Newmark-尾 method. The motion characteristics of each rotor system under certain parameters are analyzed by means of displacement diagram (vibration waveform), instantaneous frequency diagram, envelope diagram, carrier chart, phase diagram, axis locus diagram and Poincare map. The response of the rotor system with some parameters (rotational speed, rotor mass, bearing equivalent mass, eccentricity, equivalent stiffness of the shaft, etc.) and the vibration characteristics of the rotor system under coupling faults are analyzed by using the above related graphs. It lays a certain theoretical foundation for fault diagnosis under different working conditions.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH113.1

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