具有完整约束的复杂转子—轴承耦合系统非线性动力学研究

发布时间：2018-04-06 02:05

本文选题：非线性动力学　切入点：转子—轴承系统　出处：《西安科技大学》2012年硕士论文

【摘要】：在不对中故障转子—轴承系统的动力学分析中，往往忽略了转子间存在的运动约束或耦合关系，而这些约束在某些情况下有可能极大地改变系统的动力学特性。因此深入研究具有不对中约束的复杂转子—轴承耦合系统的非线性动力学行为对系统的动力学设计和故障诊断具有重要的理论及工程意义。本文以转子间具有广义位移约束关系的不对中转子系统为研究对象，基于转子动力学、非线性动力学和流体动压润滑理论，建立了具有完整约束的多转子耦合系统的动力学模型。采用数值分析以及试验方法，重点研究了在非线性轴承力作用下转子间具有定常和非定常完整约束的不对中转子—轴承耦合系统的非线性动力学行为。探讨了具有平行不对中及交角不对中约束的转子系统非线性故障振动机理和特征。主要研究内容和成果如下： 1.以国产某发电机转子为研究对象，建立了具有平行不对中和质量不平衡故障的非对称柔性转子系统力学模型，利用多种分析方法研究了系统的非线性动力学行为，并讨论了转子参数对系统动力学特性的影响。结果显示：在较低转速和微小不对中量时，系统的稳态响应主要呈现出与转速同步的周期运动特性，随着转速的提高，频域内谐波分量增多，振幅也随之增大。另外，转子间不对中量、转轴刚度不对称度以及质量偏心等参数的改变使得系统的运动更加复杂，出现分叉、跳跃以及混沌等非线性动力学现象。 2.研究了一个具有交角不对中约束的转子—轴承系统动力学行为。建立了具有非定常完整约束的柔性多转子系统动力学模型，分析了系统的非线性振动特征和参数变化对系统动力学行为的影响。数值结果表明：在较低转速时，交角不对中量对系统的运动影响较小。随着转速的增加，其轴心轨迹出现明显的“8”字形，特征频率为工频的两倍。在较高转速时，出现倍周期分叉、混沌运动等复杂动力学现象。另外，转子间的交角不对中量，转轴刚度、质量偏心等参数对系统的非线性动力学行为也具有重要影响。 3.建立了在油膜轴承支承下多转子—轴承系统试验平台，，对不对中转子的动力学特性进行了试验研究。重点探讨了平行不对中和交角不对中转子—轴承系统的动态响应，例如，频域特征、轴心轨迹等。试验结果显示：具有不对中故障的转子系统稳态响应中除了存在工频和倍频分量之外，还存在一些组合频率成分，其中工频和2倍频成分占优，这些非线性动力学现象证明了理论模型的合理性。
[Abstract]:In the dynamic analysis of rotor-bearing systems with misalignment faults, the kinematic constraints or coupling relationships between rotors are often ignored, and these constraints may greatly change the dynamic characteristics of the system in some cases.Therefore, it is of great theoretical and engineering significance to study the nonlinear dynamic behavior of a complex rotor-bearing coupling system with misalignment constraints for the dynamic design and fault diagnosis of the system.Based on rotor dynamics, nonlinear dynamics and hydrodynamic lubrication theory, this paper focuses on the misalignment subsystem with generalized displacement-constrained relationship between the rotors, which is based on the rotor dynamics, nonlinear dynamics and hydrodynamic lubrication theory.The dynamic model of multi-rotor coupling system with complete constraints is established.In this paper, numerical analysis and experimental method are used to study the nonlinear dynamic behavior of an unsteady and unsteady rotor-bearing coupling system with steady and unsteady holonomic constraints under the action of nonlinear bearing forces.The mechanism and characteristics of nonlinear fault vibration of rotor system with parallel misalignment and angular misalignment constraints are discussed.The main contents and results of the study are as follows:1.A mechanical model of an asymmetric flexible rotor system with parallel misalignment and mass imbalance is established. The nonlinear dynamic behavior of the system is studied by using a variety of analytical methods.The influence of rotor parameters on the dynamic characteristics of the system is also discussed.The results show that the steady-state response of the system mainly presents periodic motion characteristics synchronizing with the rotational speed when the speed is low or small misalignment. With the increase of the rotational speed, the harmonic component in the frequency domain increases and the amplitude increases with the increase of the rotational speed.In addition, the system motion is more complicated by the change of rotor misalignment, rotation axis stiffness asymmetry, mass eccentricity and other nonlinear dynamic phenomena such as bifurcation, jump and chaos.2.The dynamic behavior of a rotor-bearing system with angular misalignment constraint is studied.A dynamic model of flexible multi-rotor system with unsteady holonomic constraints is established, and the influence of nonlinear vibration characteristics and parameter changes on the dynamic behavior of the system is analyzed.The numerical results show that the angular misalignment has little effect on the motion of the system at lower rotational speed.With the increase of rotational speed, the axis center locus appears obviously "8" zigzag, and the characteristic frequency is twice as high as the power frequency.At higher rotational speed, complex dynamic phenomena such as period doubling bifurcation, chaotic motion and so on appear.In addition, the misalignment of the rotor angle, the stiffness of the shaft and the mass eccentricity also have an important effect on the nonlinear dynamic behavior of the system.3.A multi-rotor-bearing system test platform supported by oil film bearing is established and the dynamic characteristics of the mismatched rotor are experimentally studied.The dynamic response of the rotor-bearing system with parallel misalignment and angular misalignment is discussed, such as the frequency domain characteristics, the axis trajectory, and so on.The experimental results show that there are some combined frequency components in the steady state response of rotor system with misalignment fault, in addition to the power frequency and frequency doubling components, the power frequency and 2 times frequency are dominant.These nonlinear dynamics phenomena prove the rationality of the theoretical model.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH113

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