基于弹性支承的磁悬浮轴承转子系统振动控制

为寻找抑制磁悬浮轴承转子系统振动的有效方法,基于有限元分析软件ANSYS对转子系统附加外弹性支承前后的动态特性进行仿真对比分析,同时搭建磁悬浮轴承转子试验台进行试验验证。仿真及试验均表明,通过引入合适的外弹性支承结构,可以有效抑制系统振幅。     

球面螺旋槽动静压气体轴承试验台的研制及试验分析

为研究气体轴承的工作机理和静动态特性、设计了球面螺旋槽动静压气体轴承试验台,通过转子升降速试验分析转速-时间、碰磨电压-时间曲线,得到转子的起飞转速为15 762 r/min;通过轴承轨迹、频谱试验研究轴承-转子系统稳定运行到失稳过程的振动变化特性,进一步使用MATLAB,MYSQL数据库及数据处理系统对试验数据进行在线和离线处理,求得气体轴承刚度、阻尼等静动态特性与供气压力、转速的变化关系;通过电磁激振系统对转子进行加载试验,研究刚度、阻尼与激振频率变化关系。试验表明:试验台可测量气体轴承的转子转速、振动位移、轨迹、频谱、起飞转速及刚度、阻尼等静动态特性系数,研究气体轴承稳定运行及失稳过程静动态特性变化和运行参数对轴承静动态特性的影响。     

含轴承间隙的转子非对称支承等效力学特性模拟分析方法

轴承间隙与支承非对称广泛存在于旋转机械系统中，是转子振动跳跃、偏移、反进动等复杂振动特性产生的主要影响因素。工程中对两者耦合影响下的复杂振动机理阐释不清，相关的等效力学模拟方法也各有局限。为此提出一种含轴承间隙的非对称支承结构等效力学特性模拟分析方法。通过支承结构的周向分解，解决了现有等效力学模拟方法难以同时模拟轴承间隙与支承非对称的问题。通过对典型发动机转子系统的分析对所提方法有效性进行了验证。结果显示轴承间隙与支承非对称共存时，系统会同时表现频率分离，振动跳跃与偏移现象，并且轴承间隙与支承非对称的影响相互耦合。所提模拟方法为工程中此类复杂振动问题产生机理的深入分析奠定了基础。     

轴承安装配合方式对电主轴轴承-转子系统振动的影响

轴承-转子系统是决定电主轴单元工作性能的核心部件,而轴承的安装配合关系会直接影响系统的运行精度。考虑热膨胀和轴承内、外圈配合方式,建立了电主轴轴承-转子系统动力学模型,分析了内圈过盈配合和外圈间隙配合对转子振动特性的影响,并通过试验验证了模型的正确性。结果表明：转子振幅随内圈配合过盈量增大而减小,随外圈配合间隙量增大而增大,且外圈配合间隙量对转子振动影响更大;考虑热膨胀时的转子振幅小于不考虑热膨胀时的转子振幅。     

多间隙耦合齿轮转子系统动力学与试验研究

为了研究多间隙对齿轮转子系统动力学特性的影响,提出一种考虑多间隙耦合的齿轮转子系统动力学建模方法,并利用相应的动力学试验验证了建模方法的准确性。在动力学模型中,考虑了轴承径向间隙、动态齿侧间隙以及时变啮合刚度。分析转速和间隙大小对系统振动特性的影响规律。结果表明:从动轮加速度振动频谱主要包含径向振动频率和啮合振动频率。随着转速的提高,径向振动幅值增大,啮合振动也更为剧烈。径向间隙增大导致径向振动与啮合振动幅值升高,而齿侧间隙增大会导致机构回差增大。通过动力学验证试验,从频率和幅值上验证了理论计算和分析结果的正确性,但试验数据与理论计算之间仍存在一定误差,尤其是幅值误差较大,这些误差的主要来源是模型参数误差和测量误差。     

航空发动机轴承内环松动理论研究

研究了轴承内环松动的航空发动机转子系统的振动特性。结合内环间隙的轴承组件的结构和几何特点,研究轴承内环和锁紧螺母之间的相对运动关系。在此基础上提出了轴承内环和锁紧螺母之间滑动摩擦载荷的计算方法。建立了带有轴承内环间隙的竖式转子的动力学方程。该方程考虑了内环间隙带来的刚度非线性以及内环和锁紧螺母之间的摩擦载荷带来的阻尼非线性。数值求解动力学方程,得到转子系统的振动响应如波形、频谱和轴心轨迹等。定量研究转子结构参数,如转子的不平衡量、内环间隙尺寸和锁紧螺母拧紧力矩等对转子振动特性的影响。结果表明:内环端面和锁紧螺母之间的内摩擦取决于它们的相对运动关系,正比于锁紧螺母拧紧力矩,并可能促进转子同步正进动,进而导致转子失稳;转子失稳时,振动响应包含系统固有频率、工频及固有频率和工频的差频3种等频率成分;转子不平衡量、内环间隙大小和锁紧螺母拧紧力矩等均对转子的失稳产生影响;合理控制这些参数可以避免因内环松动导致的转子失稳。     

轴承结合面间隙对转子支承系统动态特性影响

针对目前工程中凭经验通过人为调节滑动轴承结合面间隙来抑制汽轮机转子振动,缺少理论依据的现状,建立考虑滑动轴承瓦壳顶隙、水平侧隙影响的转子支承系统动力学模型,分别采用有限差分法和有限元法分析调节结合面间隙对滑动轴承动特性参数和转子系统振动特性的影响。分析结果表明,随结合面间隙增大轴承的偏心率、各向支承刚度及交叉阻尼分量(c_(yx))呈非线性减小,偏位角呈非线性增加,转子系统前6阶固有频率略微减小,对由转子质量偏心激励引起的振动响应有明显抑制作用,轴承结合面间隙对系统动态特性的影响不可忽略。     

大间隙环流中复杂轴承-转子系统振动特性研究

基于Myklestad传递矩阵法建立了大间隙环流中动压滑动轴承-转子系统的运动方程，用迭代方法确定了轴承．转子系统的静态平衡工作点，采用数值方法分析轴承-转子系统的振动特性。数值计算结果表明：大间隙环流使轴承-转子系统的固有频率、阻尼临界转速和稳定性均发生了不同程度的变化。大间隙环流不仅与轴承．转子系统发生了动态固耦合，而且也发生了静态固耦合。     

滚动轴承转子系统的非线性动力学特性分析

接触非线性和间隙非线性耦合导致滚动轴承 转子系统表现出复杂的动力学特性 ,在工作转速范围内系统会产生分岔混沌振动 ,从而影响系统工作的稳定性和可靠性 ;在计及轴承接触非线性和径向间隙的条件下 ,建立了滚动轴承支承的水平刚性转子系统的非线性动力学模型 ,用数值积分方法得到系统在不同参数域中的相图、轴心轨迹、频谱图及Poincar啨映射图 ,研究了系统响应随转子转速的变化趋势。结果表明 :轴承的径向间隙是决定轴承 转子系统动态响应的一个重要参数。随着间隙的增大 ,混沌响应区变宽 ,轴承的动态刚度减小 ,故在设计滚动轴承 转子系统时 ,应对径向间隙进行优选。     

主动电磁轴承失效后转子坠落在备用轴承过程中的非线性动力学

用有限元法建立了任意个由滚动轴承组成的固定间隙备用轴承-主动电磁轴承-多盘多质量转子系统在主动电磁轴承失效前后的动力学方程,以一个多盘转子系统为例分析了主动电磁轴承失效后转子坠落在备用轴承过程中的瞬态非线性动力学特性,讨论了柔性备用轴承的支撑刚度、支撑阻尼和间隙对转子在坠落过程中动力特性的影响。结果表明采用具有较大阻尼柔性结构的备用轴承能够显著地改善转子坠落在备用轴承上的瞬态动力特性,抑制转子在坠落过程中可能出现具有较大振动和冲击力的全间隙区的涡动运动,减小转子坠落对备用轴承寿命和可靠性的影响。柔性结构备用轴承的支撑阻尼越大,支撑刚度越小,间隙越大,转子坠落后出现全间隙区涡动运动的可能性越小。     

Effects of Floating Ring Bearing Manufacturing Tolerance Clearances on the Dynamic Characteristics for Turbocharger

The inner and outer oil film dynamic characteristic coefficients of floating ring bearings(FRBs) change due to the manufacturing tolerance of the floating ring, journal and intermediate, which leads to...     

浮环轴向长度对高速轻载涡轮增压器转子系统振动特性影响研究

浮环轴承内外轴向长度结构参数会影响油膜压力分布与偏心率,产生显著分频振动而引发高速轻载涡轮增压器转子非线性振动故障。基于流体润滑理论和浮环力矩平衡方程,推导了含浮环轴承的涡轮增压器转子系统动力学方程,揭示浮环轴承轴向长度与转子系统振动响应之间的关系。以某型汽油机用涡轮增压器转子系统为例,分析浮环内、外轴向长度对轴承油膜压力、偏心率等动力特性的影响,构建转子系统动力学有限元模型,通过三维振动瀑布图研究不同浮环轴向长度下转子系统频域瞬态振动响应,结果表明：浮环内轴向长度从2.6增加到4.6 mm,导致浮环转速升高,最大内油膜压力减小,轴颈偏心率降低,分频幅值增加且出现分频的轴颈转速由142 kr/min降至76 kr/min,更易产生明显的非线性涡动现象;浮环外轴向长度从3.6增加到6.15 mm,使浮环转速降低,最大外油膜压力变小,浮环偏心率及轴颈相对浮环的偏心率减小,低转速下分频幅值减少且出现分频的轴颈转速由10 kr/min升至22 kr/min,可抑制转子系统过早发生非线性涡动,为浮环轴承结构参数设计与试验提供理论支撑。     

油孔数量对浮环轴承润滑特性的影响

不同油孔数量会改变浮环轴承油膜润滑特性,从而影响转子的振动特性及稳定性。基于流动连续性方程与轴承润滑理论,推导浮环轴承油膜控制方程,揭示油孔数量与浮环轴承润滑特性之间的关系。以某型汽油机用涡轮增压器浮环轴承为例,构建浮环轴承有限元模型,基于计算流体力学方法分析油膜润滑特性,研究不同油孔数量对浮环轴承最大压力、油膜承载力及动力学特性系数的影响。结果表明：浮环油孔数量从2增长到8,内外油膜最大压力、外油膜承载力及油膜动力学特性系数下降,内油膜承载力上升;内油膜承载力在油孔数量为2时随着转速的上升而逐渐下降,在油孔数量为4时无明显变化,在油孔数量为6、8时随着转速的上升而上升;随着转速的上升,油孔对承载力的影响逐渐上升,而对最大压力及动力学特性系数的影响逐渐减小。     

Characteristics analysis of aero-engine whole vibration response with rolling bearing radial clearance

For the influence of rolling bearing radial clearance on the whole vibration in the aero-engine whole system, a real engine rotorbearing- casing whole model is established. The rotor and casing systems are modeled by means of FEM; the support systems are modeled by lumped-mass model; rolling bearing radial clearance and strong-nonlinearity of Hertz contact force at four different supports are considered. The coupled system response is obtained by the numerical integral method. The characteristics of the whole vibration response are analyzed. For rolling bearing at a typical support, the rotor, outer ring of rolling bearing and casing response characteristics at different rotating speeds are analyzed. The changing law of contact forces for each ball and the global contact forces at different speeds are analyzed. The influence of the radical clearance on the contact forces on the whole vibration is analyzed. The results show that the contact forces will be larger and the acceleration amplitude jumps obviously when the radial clearance is increased, and due to the variable stiffness of the rolling bearing, the natural frequency will appear when the stiffness changes fiercely, that is frequency-locked phenomenon. When the radical clearance is larger and the rotating speed is between two critical speeds, the rotor squeezes the outer ring now and then. Reducing the radical clearance can reduce the whole vibration and increase the rotor’s stability.     

Effects of semi-floating ring bearing outer clearance on the subsynchronous oscillation of turbocharger rotor

Semi-floating ring bearing(SFRB) is developed to control the vibration of turbocharger rotor. The outer clearance of SFRB affects the magnitude and frequency of nonlinear whirl motion, which is significant for the design of turbocharger. In order to explore the effects of outer clearance, a transient finite element analysis program for rotor and oil film bearing is built and validated by a published experimental case. The nonlinear dynamic behaviors of rotor-SFRB system are simulated. According to the simulation results,two representative subsynchronous oscillations excited by the two bearings respectively are discovered. As the outer clearance of SFRB increases from 24 μm to 60 μm, the low-frequency subsynchronous oscillation experiences three steps, including a strong start, a gradual recession and a combination with the other one. At the same time, the high-frequency subsynchronous oscillation starts to appear gradually, then strengthens, and finally combines. If gravity and unbalance are neglected, the combination will start starts from high rotor speed and extents to low rotor speed, just like a "zipper". It is found from the quantitative analysis that when the outer clearance increases, the vibration amplitude experiences large value firstly, then reduction, and suddenly increasing after combination. A useful design principle of SFRB outer clearance for minimum vibration amplitude is proposed: the outer clearance value should be chosen to keep the frequency of two subsynchronous oscillations clearly separated and their amplitudes close.     

含柔性转子的齿轮-轴承系统动态特性分析

为了分析齿轮系统动力学中的全耦合振动,提出采用虚拟样机建模的方法,将柔性转子引入到啮合耦合系统中,考虑齿轮时变啮合刚度、齿侧间隙和轴承间隙的影响,建立齿轮-柔性转子-轴承系统虚拟样机模型,通过求解模型的动力学方程得到系统的非线性动力学响应。仿真结果表明:考虑柔性转子的耦合系统,啮合冲击峰值下降明显;转子柔性增加,齿轮低频扭转振动出现"拍"现象;高速轻载时啮合振动非线性特性增强;轴承间隙增大使啮合力振动幅值显著增大。     

基于显式有限元的转子不平衡与轴承故障耦合分析

为分析转子不平衡与轴承故障耦合振动特征及产生机理,在对转子不平衡与轴承故障耦合状态下受力分析的基础上,基于虚位移原理的增广拉格朗日法建立轴承运动控制方程,运用LS-DYNA建立转子-轴承系统二维显式动力学有限元模型,分析了故障耦合状态下轴承振动加速度、转子轴心运动轨迹,探明了转子不平衡-轴承缺陷耦合故障冲击响应特征及转子轴心运动轨迹突变机理,并通过试验进行了验证。结果表明:转子不平衡与轴承外圈故障耦合状态下,轴承座测点位置故障特征频率被转频调制,冲击幅值随转频变化;转子轴心轨迹呈椭圆形,且缺陷位于轴承承载区时,转子轴心轨迹存在突变。     

Dynamic characteristics of spindle with water-lubricated hydrostatic bearings for ultra-precision machine tools

A key component of ultra-precision machine tools is the spindle. The motivation for this study was to improve machining accuracies in precision cutting and grinding by pursuing improvements in the spindle characteristics by designing a sophisticated spindle with water-lubricated hydrostatic bearings. The static bearing stiffness of the developed spindle was investigated in previous studies. In addition to the static bearing stiffness, the dynamic characteristics regarding bearing stiffness also affect significantly on the machining results. In this study, dynamic characteristics of the developed spindle with water-lubricated hydrostatic bearings were investigated via simulations and experiments. Not only bearing dynamics but also rotor dynamics were considered in this study.In the simulation studies, the spindle dynamic characteristics were analysed based on the transfer matrix method. A spindle rotor supported with hydrostatic bearings was represented by discrete sections of the rotor. The mathematical model of transverse linear vibrations of the spindle rotor was derived with distributed parameters for these discretized rotor sections. As a result of the analysis on the amplitude-frequency characteristic, radial displacements of the rotor due to bearing displacement and bending deformation were defined. Then, the frequency characteristics were represented with Nyquist plots. Resonant frequencies and amplitudes formation in the transverse vibration of the rotor were determined. The influence of rotor bending deformations on spindle compliance was assessed. Furthermore, the study examined the influences of the supply pressure of the lubricating fluid, radial clearance and journal diameter of the hydrostatic bearings on the amplitude of the rotor vibration, and the resonance frequency of the system.Furthermore, the dynamic characteristics of the spindle were examined experimentally. The simulation results were in good agreement with the actual spindle dynamics obtained experimentally. The influence of the structural parameters of the rotor and the operating parameters of the bearings on the spindle dynamic characteristics was also determined. It was verified that the amplitude of the vibration of the rotor overhang part was dominantly affected not by bearing stiffness but by bending stiffness of the bearing journal of the front bearing and the length of the rotor overhang.Then it was verified that the resultant displacement of the rotor in the radial direction due to the influence of the bearing characteristics and the structural effect of the rotor is significantly small. Practical recommendations to improve the spindle design in terms of the dynamic characteristics of the spindle with water-lubricated hydrostatic bearings were also derived.     

改进PCA算法及其在转子特征提取中的应用

为探索航空发动机轴承装配条件对支承刚度的影响，支撑发动机转子系统的动力学设计和整机振动控制，在动力学方程的基础上，建立了振动测试和理论计算相结合的支承刚度辨识方法，并以某型航空发动机的五号支点轴承为对象，试验研究了圆柱滚子轴承内、外环配合参数、锁紧螺母拧紧力矩等参数对支承刚度的影响规律。结果表明：建立的支承刚度辨识方法准确可行；轴承内、外环为过盈配合时，过盈量增大，支承刚度增大，支承刚度对锁紧螺母拧紧力矩不敏感；轴承内、外环为间隙配合时，转子出现非线性共振，支承刚度大幅度地随机跳动，不符合线性条件假设。设计时应合理考虑轴承内、外环配合参数，避免导致转子系统振动特性恶化。     

Vibration response of rigid rotor in unloaded rolling element bearing

Rolling element bearings appear in nearly 90% of all rotating machinery. Their dynamic performance is often the limiting factor in the performance of the machines that use them. The specific construction of a bearing has a decisive influence on its dynamic behaviour. The paper defines a new vibration model of a rigid rotor supported by rolling element bearings. By application of the defined model, the parametric analysis of the influence of internal radial clearance value and number of rolling elements influence on rigid rotor vibrations in unloaded rolling element bearing was performed. The defined vibration model and parametric analysis were verified experimentally. The results of experimental analysis are also presented in this paper.