【作者】 刘静；

【导师】 邵毅敏； WeiDong Zhu；

【作者基本信息】 重庆大学 ， 机械设计及理论， 2014， 博士

【摘要】 据统计，旋转机械30%的故障和大型异步电机44%的故障是由故障轴承引起的。滚动体在通过缺陷位置时会产生冲击脉冲，其冲击脉冲的幅度和波形与缺陷的形状和尺寸直接相关，对缺陷形状和尺寸与其冲击脉冲波形之间的关系和冲击脉冲响应特征的认识程度将直接影响轴承运行状态判定的正确性与可靠性。因此，要准确预测和识别轴承早期故障，防止因轴承突发故障造成的重大经济损失和人员伤亡，需要解决滚动轴承内部早期缺陷故障诱发的非线性激励机理及其振动响应特征这个基础性关键科学问题。然而，轴承内部接触的非线性、轴和轴承座的耦合作用等因素的存在，以及滚动轴承经常处于变速和变载工况等因素的影响，对滚动轴承故障，尤其是早期局部缺陷故障的形状和尺寸与其冲击响应特征之间的关系尚未解明，制约了早期故障诊断的准确性和可靠性。因此，开展滚动轴承早期缺陷故障非线性激励机理及建模方法的研究，具有重要的理论意义和实际工程应用价值。针对滚动轴承缺陷非线性激励机理与建模问题，开展波纹度和局部缺陷激励机理，时变位移激励和时变接触刚度激励耦合的滚动轴承缺陷动力学建模，滚动轴承缺陷边缘形貌特征演变的内部激励机理及动力学建模，轴-滚动轴承-轴承座系统内部激励的振动传递与动力学建模，以及台架实验验证等研究工作。论文的主要研究内容：①针对目前时变位移激励均匀波纹度模型难以准确描述均匀和非均匀波纹度诱发的滚动体与波纹度滚道之间时变接触刚度激励的问题，提出了时变位移激励和时变接触刚度激励耦合的滚动轴承波纹度动力学模型，分析了波纹度波数、幅值和非均匀分布形式对滚动体与内、外圈滚道波纹度表面之间的接触刚度和振动响应特征的影响规律，揭示了波纹度与滚动轴承通过频率及边频之间的关系。②针对目前基于单一函数的时变位移激励局部缺陷动力学模型不能准确描述实际局部缺陷表面轮廓诱发的振动响应特征问题，基于局部缺陷的实际表面轮廓形态特征，提出了滚动轴承滚道表面局部缺陷表面轮廓特征的简化表征模型，查明了不同轮廓特征局部缺陷的内部激励机理及其冲击响应特征，提出了不同轮廓形貌局部缺陷诱发冲击波形的基本表征模型，并通过台架实验验证了模型的正确性。③基于分段函数提出了时变位移激励和时变接触刚度激励耦合的滚动轴承局部缺陷动力学模型，克服了基于单一函数的时不变和时变位移激励局部缺陷模型无法描述局部缺陷边缘的弹性变形与局部缺陷深度对轴承振动响应特征影响的不足，创新了目前基于单一函数的局部缺陷模型，经与台架实验测试结果进行对比分析，验证了模型及其计算结果的正确性，解决了不同类型局部缺陷的内部激励表征与动力学建模难题。④基于滚动体与局部缺陷形貌特征及接触内在关系表征的思想，构建了局部缺陷边缘形貌特征演变诱发时变位移激励、时变接触刚度激励与局部缺陷尺寸之间关系的表达式，并基于Hertz接触理论建立了滚动轴承局部缺陷边缘形貌特征演变动力学模型，克服了基于尖锐边缘假设的滚动轴承局部缺陷动力学模型无法准确描述缺陷边缘形貌特征演变对滚动体与缺陷边缘之间的接触刚度及振动响应特征的缺点，创新了滚动轴承局部缺陷动力学模型，为滚动轴承局部缺陷边缘形貌特征随机演变动力学的建模奠定了基础。⑤考虑滚动体与滚道之间、轴承外圈与轴承座之间弹性界面的影响，提出了弹性界面的轴-滚动轴承-轴承座系统内部激励的振动传递动力学模型，克服了目前刚性界面的轴-滚动轴承-轴承座系统内部激励振动传递动力学模型，无法准确描述轴承内部激励引起的轴承外圈与轴承座振动响应特征之间的差异，以及不能解释轴承内部激励振动与轴承座振动之间的传递机理的缺点，研究了轴承内部激励沿轴-滚动轴承-轴承座系统弹性界面的振动传递规律，经与台架实验结果进行对比分析，验证了模型的正确性。更多还原

【Abstract】 30%and44%present of the total number of failures in rotating machinery andlarge induction motors are caused by bearing failures. When a rolling element passesover the defect, an unacceptable impulse will be generated. The amplitude andwaveform of the impulse is determined by the shape and sizes of the defect. Theunderstanding of the relationships between the shape of the defect, the sizes of thedefect, and the waveform of the impulse, and as well as the vibration characteristics ofthe impulse is very useful for the accuracy and reliability of the determination of theoperation status of the rolling element bearing. Therefore, it is an important theoreticaland practical task to investigate the nonlinear vibration mechanism of the defect andthe vibration characteristics of the impulse cause by the defect for the accuracy of thedetection and diagnosis of the early bearing faults, and the prevention of the severeeconomic, personal and equipment losses cause by the bearing failures.However, the relationships between the shape of the early localized defect, thesizes of the early localized defect, and the characteristics of the impulse caused by thedefect in the rolling element bearing are not completely understood due to the effectsof the nonlinear contacts in the bearing, the coupling with the shaft and housing, thetime-varying rotating speed, and the time-varying loads on the vibration characteristicsof the bearing. Therefore, it is of great theory value and engineering significance toinvestigate the nonlinear vibration mechanism and the dynamic modeling method ofthe rolling element bearings with early defects.This thesis is focused on the nonlinear vibration mechanism and the dynamicmodeling method of the defects in the rolling element bearings, including the vibrationmechanism of the waviness and the localized defect, the dynamic modeling of therolling element bearings considering the time-varying displacement excitation and thetime-varying contact stiffness excitation, the dynamic modeling of the rolling elementbearings due to a localized defect with edge topography progress, the dynamicmodeling of the impulse vibration transmissibility characteristics in a rotor-rollingelement bearing-housing system, and the corresponding experimental validation. Themain works done in this study are as follows:①The time-varying contact stiffness excitations between the rolling element andthe races for the uniform and nonuniform waviness cannot be accurately described by the current waviness model considering the time-varying displacement excitation. Toovercome this problem, a new dynamic model coupling the time-varying displacementexcitation and the time-varying contact stiffness excitation for a rolling elementbearing with waviness is proposed. The effects of the wave numbers and the amplitudeof the waviness on the contact stiffness between the rolling element and the races ofthe bearing, and the vibrations of the bearing are investigated. The relationshipsbetween the waviness and the rolling element passing frequencies are investigated, aswell as the sidebands around the maximum peak frequency of the rolling elementpassing frequencies.②The complex practical topography of the localized defect cannot be accuratelydescribed by the time-varying displacement excitation localized defect models basedon single functions. To overcome this problem, a simplified model for describing thetopography of the defect is proposed according to the practical topography of thedefect. The impulse mechanism of the defect with different topographies and thevibration characteristics caused by the defects are investigated. A main function modelfor the waveform of the impulse generated by the defect is also presented. In addition,an experimental investigation is performed to validate the proposed model.③The effects of the elastic deformations at the edges of the localized defect andthe defect depth on the vibration characteristics of the rolling element bearings cannotbe described by the current localized defect models considering the time-invariant andthe time-varying displacement excitation based on single functions. To overcome thisproblem, the current localized defect models based on single functions are extended,and a new dynamic model based on the piecewise response function for the rollingelement bearings with a localized defect coupling the time-varying displacementexcitation and the time-varying contact stiffness excitation is proposed. Anexperimental investigation is also developed to verify the proposed model. Itovercomes the problems of dynamic modeling methods for the different localizeddefects in the rolling element bearings.④The effects of the topographies progresses at the defect edges on the contactstiffness between the rolling element and the defect edge, and the vibrationcharacteristics of the bearing caused by the defect cannot be accurately described bythe current localized defect models considering sharp defect edges. To overcome thisproblem, the relationship expressions for the time-varying displacement excitation andthe time-varying contact stiffness excitation caused by the localized defect with the topographies progresses at the defect edges are derived according to the ratio of therolling element diameter to the minimum defect size and the ratio of defect length to itswidth. Based on Hertzian contact theory, a dynamic model of a rolling element bearingwith a localized defect on its races considering the topographies progresses at thedefect edges is proposed. The current defect models considering the sharp defect edgesare extended. It provides the theoretical bases for the accurate dynamic modelingmethod of the rolling element bearings with a localized defect considering thetopographies progresses at the defect edges.⑤The dynamic model of the rotor-rolling element bearing-housing systemconsidering rigid connection between the outer race and the housing cannot accuratelyexplain the differences of the vibrations between the outer race and the housing.Moreover, it cannot represent the vibratory motion transmitted from the outer race intothe housing and other connecting components. To overcome this problem, a newvibration transmissibility dynamic model of the rotor-rolling element bearing-housingsystem considering elastic interfaces between the rolling element and the races, andbetween the outer race and the housing is proposed. The dynamic model of therotor-rolling element bearing-housing system considering the rigid connection betweenthe outer race and the housing is extended. The vibration transmission characteristicsthrough the rotor-rolling element bearing-housing system are studied. An experimentalvalidation is applied and shows agreement with the numerical results from theproposed model.更多还原