Experimental investigation of the effect of lead errors on helical gear and bearing vibration transmission characteristics

The characteristics of gear meshing vibration undesgo change as the vibration is transmitted from the gear to the housing. Therefore, vibration transmission characteristics of helical gear systems must be understood before the effective methods of reducing gear noise can be found. In this work, using a helical gear with different lead errors, the gear vibration in the rotational direction and the bearing vibration are measured. The frequency characteristics of gear and bearing vibration are investigated and a comparson is also provided.     

车用发动机凸轮轴轴承松脱的故障特征提取

车用发动机凸轮轴轴承松脱故障使得凸轮轴受力不均而引起冲击力,导致凸轮轴附近机体表面出现异常振动和显著噪声。通过对某发动机凸轮轴轴承松脱故障的试验测试,提取缸盖振动加速度信号进行时域分析,发现有明显的周期性冲击;利用小波包分解至较高频段并做解调分析,解调谱的故障激励频率非常显著。分析结果表明,凸轮轴轴承松脱故障有中高频调制现象,可综合利用时域分析、频谱分析和小波包分解与解调分析进行相应的故障特征提取。     

电磁轴承系统中的辅助轴承与振动影响

出于安全性考虑,实验或应用中的电磁轴承系统通常需要考虑安装辅助轴承。由于辅助轴承并非具有实质性的支承作用,因此一般情况下,在电磁轴承系统设计时,对辅助轴承的振动情况及其对整个磁悬浮系统的影响考虑是极少的。通过一台磁悬浮铣床电主轴样机的实验结果表明,辅助轴承的振动影响有时不仅不能忽略,甚至它对系统的安全运行的影响是至关重要的。     

列车用橡胶堆旁承的两种本构模型振动特性研究

对列车用橡胶堆旁承以Mooney-Rivlin模型和Yeoh模型进行建模,利用ABAQUS计算分析软件计算出两种模型在相同载荷下的载荷位移曲线,分别计算出其非线性刚度特性;对橡胶堆旁承建立振动微分方程,将求得的两种本构模型的非线性刚度代入微分方程中,通过求解微分方程求得两种本构模型的相频和幅频特性,得出两种本构模型的振动传递特性。该研究结果在橡胶元件设计中有一定的意义。     

The effect of vibration on the hemorheological characteristics of non-aggregated blood

The present study investigates the hemorheological characteristics of blood flow with applying vibration to a non-aggregating red blood cell suspension. In order to obtain the non-aggregating RBC suspension, blood samples were treated with vibration at a specified condition, which viscosities were taken before and after the treatment, respectively. The viscosity of the blood samples after treatment was higher than before treatment. These treated blood samples were forced to flow through a capillary tube that was vibrated perpendicularly to the direction of the flow. The experimental results showed that vibration caused a reduction of the flow resistance of the non-aggregated blood. The reduction of the flow resistance was strongly dependent on both frequency and amplitude of vibration. These results show potential in treating various diseases in the microcirculation associated with blood cell aggregation.     

The effect of variable permeability on the performance characteristics of porous bearing

An analytical solution for the performance characteristics of a short bearing having an axial and radial permeability of $\text{k}{}_{\mathrm{z}}\text{[1 + cos(}\text{πz}\text{L}\text{)]}$ and $\text{k}{}_{\mathrm{z}}\text{[1 + (}\text{2}\text{π}\text{)]}$, respectively, is obtained. Results are presented which relate the eccentricity ratio and coefficient of friction as functions of load number for various design variables. These results are compared to the results obtained for an isotropic bearing having a permeability of $\text{k}{}_{\mathrm{z}}\text{[1 + (}\text{2}\text{π}\text{)]}$.     

内部裂纹对轧辊振动特性影响的研究

建立了含内部裂纹轧辊的有限元模型,计算了轧辊的固有频率,分析了轧辊内部裂纹对轧辊固有频率的影响规律,为探索通过振动特性识别轧辊的裂纹损伤提供了依据.     

轴承振动的测量

通过分析轴承振动的产生原因,找出解决办法并加以检测,使轴承的振动得到了有效控制。     

柴油机供油提前角对曲轴主轴承动载荷的影响

针对柴油机曲柄连杆机构整体模型,采用多体动力学方法建立柴油机曲轴动力学模型,分析了不同供油提前角下曲轴主轴承动载荷的变化,仿真过程中对曲轴进行柔性处理,同时计入油膜的动力润滑作用,将不同提前角下曲轴主轴承载荷进行比较,得出供油提前角对柴油机的影响规律。     

滚动轴承振动的模拟及试验研究

根据目前最新的理论研究成果,建立了滚动轴承的振动模型;通过同一轴承振动加速度频谱的理论模拟结果与试验结果的比较,得出符合性的结论。     

铁路轴承振动质量对可靠性的影响

通过对内滚道几何精度引起的轴承振动进行评估,理论上分析这些振动加速度对铁路轴承可靠性的影响趋势,承振动质量验收提供依据。得出这些几何精度所能产生的振动加速度,并从为铁路轴承生产过程中的质量控制及成品铁路轴     

轴承零件波纹度和轴承振动测量的关系

详细地分析了轴承零件波纹度和反映轴承振动的速度、加速度这两个物理量的关系，得出利用速度这个物理量来分析轴承性能更科学的结论。     

The effect of humidity on dry bearing torque

Indentation-recovery experiments have been performed on a polytetrafluoroethylene-glass fibre composite which is used as liner material in unlubricated bearings. A high humidity (relative humidity, 80%) is associated with greater resilience and also with a reduced relaxation of the bearing liner material. Bearings using this liner material exhibit a greater torque on increasing the humidity or lowering the temperature. These changes are reversible and at constant humidity and temperature stable torque values are attained after about 20 h. It is argued that variations in torque arising from small temperature changes are primarily caused by the associated change in relative humidity rather than by modulus or friction effects.     

Load effect on the vibration characteristics of a stage with rolling guides

This paper aims to investigate the dynamic characteristics of a loading stage with a rolling guide. In practice, the rolling guide is designed with different contact geometries to withstand various loads in service; it forms a rolling interface with contact stiffness varying with the applied loads. To model the rolling contact mode realistically, different contact modes were assumed at the interfaces between the ball and raceway and simulated by using spring elements with stiffness calculated by using the Hertzian contact theorem. The vibration characteristics of the rolling guide were determined by the proposed method and successfully verified by experimental vibration tests. As validation of the proposed method, a loading stage with rolling guides was also demonstrated to have different dynamic characteristics as various loads were applied, with the results from the experiments correlating to the finite element simulations. This paper was recommended for publication in revised form by Associate Editor Jeong Sam Han Jui-Pin Hung received the B.S. and M.S. degrees in Mechanical Engineering from National Chiao Tung University, Hsinchu, Taiwan in 1981 and 1983, respectively, and his Ph.D. degree from National Chung Hsing University in 2002. Dr. Hung is currently an associate professor at the Department of Mechanical Engineering at Chin Yi University of Technology in Taichung County, Taiwan. His research interests are in the area of machine tool design, failure analysis of mechanical components and orthopedic biomechanics.     

基于神经网络的滚动轴承振动预测

以神经网络与MATLAB实现理论为依据,提出了一种新的滚动轴承振动预测方法。这种方法根据轴承的加工质量试验数据,建立轴承振动预测的BP网络试验模型,在MATLAB开发环境下输入训练样本数据矩阵和目标矩阵。经过训练后,网络误差达到要求,预报结果的最大相对误差小于10％。     

The nonlinear and ball pass effects of a ball bearing on rotor vibration

A ball bearing is generally assumed as a linear spring in rotor dynamic analysis. In real case, the force equilibrium of the bearing is changed as the relative position, of each ball with respect to the direction of radial force. So, the stiffness of the bearing is also changed and is a function of time and position. In this study, the nonlinear characteristics of a ball bearing are considered in analyzing the vibration response of a rotating shaft due to an unbalance force. A finite element method is used to analyze the vibration characteristics of a rotor-bearing system and a direct numerical integration is performed to calculate the transient response of the rotor system. The responses are converted to the frequency domain and the effects of the parametric excitation due to a ball bearing are examined. The test rig for the investigation of the effect of a ball bearing on the rotor vibration is set up and the results are compared with those of numerical calculation. The calculation results show that the amplitudes of the nonlinear model are larger than those of the linear one. The frequencies of the calculations can be matched to the measured frequencies.     

重型轴承偏斜角对其寿命的影响

以轧钢机用四列圆锥滚子轴承为研究对象,通过计算轴承在不同偏斜角状况下的疲劳寿命,并分析了在偏斜角状况下轴承疲劳寿命的变化趋势,总结出轧钢机用四列圆锥滚子轴承偏斜角对其疲劳寿命的影响,为长寿命重型轴承的设计提供一个技术依据。     

Float characteristics of a squeeze-film air bearing for a linear motion guide using ultrasonic vibration

The float characteristics of a square squeeze-film air bearing using piezoelectric actuators as a vibrator are discussed. In this type of bearing, piezoelectric actuators are adhered to a flat bearing plate and vibrate the bearing plate at ultrasonic resonant frequency. The influence of various design parameters on the float characteristics of the proposed bearing, such as the vibration frequency, input voltage to the piezoelectric actuator, and imposed load were investigated theoretically and experimentally. Our proposed squeeze-film air bearing was found to be quiet, because this type of bearing uses ultrasonic vibration to generate the squeeze-film. An average film thickness of 5 μm could support an imposed load of 10 N.     

滚动轴承的结构振动问题

讨论了由轴承本身的结构性质引起的振动 ,即弯曲振动 (或称结构振动 ) ,利用虚位移原理推导出该振动频率及量级与轴承结构参数大小之间的数学表达式 ,并用实例说明 :对低噪声轴承设计而言 ,该因素是不容忽略的。附图 1幅 ,表 1个。     

轴承振动测量仪器的改进

介绍了轴承振动测量仪器速度型及加速度型的工作原理及现状,对原有的老旧轴承加速度型振动测量仪器进行了改造,使仪器重量减轻,维修方便,润滑不漏油;通过示波器显示图形获得的测量数据更有针对性地分析出影响轴承产品质量的具体原因,对高效、准确地测量轴承振动值具有重要意义。