基于超声微驱动的超声波振动减摩机理

将超声电动机定子和转子接触区定子表面一点的超声波振动分解成水平振动和垂直振动 ,并分析了两个方向振动对超声电动机驱动作用的影响。提出水平振动产生摩擦驱动力 ,垂直振动影响水平驱动的效果 ,将垂直方向超声波振动的作用等效为普通滑动试验中引入垂直滑动方向超声波振动的作用研究 ,揭示了垂直方向超声波振动是导致超声驱动动摩擦因数降低的原因     

GPS天线相位中心偏差对GPS高程的影响及改正研究

本文采用室外测定GPS天线相位中心垂直分量偏差的差值实验,对同种类型同种型号、同种类型不同型号以及不同类型的天线组合,进行实际测定,并对观测数据进行了详尽的处理和数值分析。研究了天线相位中心垂直分量偏差影响GPS高程精度的规律,提出并讨论了减弱或消除GPS天线相位中心垂直分量偏差影响的方法。实际算例表明,采用相位中心变化的模型函数改正GPS天线相位中心的偏差值,虽然在水平方向效果不明显,但有助于垂直方向偏差分量的改善。     

电磁阻尼器在线消除转子不平衡振动实验

研究了利用电磁阻尼器在线消除旋转机械运行过程中产生的不平衡振动问题.在分析电磁阻尼器的在线平衡原理基础上,建立了一套电磁阻尼器-转子系统实验台.通过控制两对磁极增益电流的大小及相位,实现了在转子上施加同频的电磁平衡力,达到了消除转子本身不平衡力的目的.研究结果表明,通过对电磁力的相位和大小进行优化控制,可以使2号轴承的水平和垂直方向振动分别降低了69%和55.6%,平衡后两个测量平面的同频振动分量均未超过10μm.实验结果证明,所采用的电磁阻尼器可以在不停机的情况下,对转子进行有效在线平衡,有助于延长转子的稳定运行周期.     

基于全矢谱的旋转机械回转相位及应用研究

研究了旋转机械故障诊断中转子截面相互垂直两个同频信号的相位差信息,揭示了相互垂直两个信号的不同相位差对应不同的合成运动轨迹图形,推导出全矢谱分析理论中初相位的角度大小,并由初相位绘制出双截面、多截面转子的空间振形,最后通过实例将全矢谱理论结合转子空间振形和初始相位差信息应用到旋转机械不平衡故障分类中。结果表明:由初相位绘制的空间振形图可以有效地区分旋转机械不平衡故障中发生的具体形式,提高了故障诊断的准确性。     

一种两轴限位的一维转台设计及应用

为了实现测量功能,需要天线在水平、垂直两个方向进行高频运动,模拟振动的信号源,采集天线在振动峰值的信号。文中设计为一维转台,用平面旋转运动代替水平、垂直方向的直线运动,从而避免两向运动的耦合问题以及高频运动的驱动问题。     

物料由于阻尼和质量结合对振动槽运行状态的影响(续)

结合系数的计算如果用槽体的垂直加速度来除通过谐波分析得到的惯性力,便可得出在垂直方向上结合在槽体上的等效质量m_(ψY)。在水平方向上的也可以类似地由摩擦力的惯性力分量及水平方向的槽体加速度求得。这两个等效质量一般是不相等的。     

新型并联冗余驱动地震模拟台

提出一种新型冗余驱动并联模拟平台。水平方向分别有二个驱动接口模块和一个驱动接口模块,垂直方向有三个驱动接口模块。垂直方向的三个驱动接口模块附加配重。每个驱动接口模块均可由一根或两根滚珠丝杠驱动。双丝杠驱动时,输入单元局部并联,经均力机构转化为系统的单一输入。利用该平台构造了一个8输入6输出的地震模拟台,将垂直方向和水平方向的丝杠寿命分别提高18倍和8倍,为地震模拟台使用电气机械系统驱动提供了可行的途径。     

四足爬壁机器人的航向偏差感知及步态调整

针对GIS管道内部故障缺陷检测，研究设计了一种四足爬壁机器人，可完成在水平和垂直管道内壁的整周爬行和轴线方向爬行。为解决管道四足爬壁机器人长时间运动产生的严重偏航问题，提出了一种不依赖外部传感器的姿态自感知与调整算法，实现了机器人姿态的自调整，保证运动的准确性。通过使用所研究的爬壁机器人在管道内进行爬行实验，包括姿态调整与爬壁运动两项运动验证，机器人实现了在水平和垂直管道内的整周爬行和轴线方向的爬壁运动，爬行运动过程中稳定性高，且在出现偏航超过设置状态时，可自发进行调整，验证了所规划的基本运动步态和姿态感知与调整算法的有效性。     

汽车自适应车灯控制系统数学模型的研究

研究了汽车自适应车灯控制系统中车灯光轴沿水平和垂直两个方向上的偏转角度与车辆参数及外界环境的关系,建立了其水平和垂直两个方向上的数学模型及车灯自动变光、开关、延时关闭模型。     

汽车排气系统的模态实验分析

汽车排气系统的振动是影响汽车振动噪声和舒适度的主要因素之一,掌握其动态特性对优化汽车的NVH性能十分重要.针对某国产轿车的排气系统进行研究,利用B&K数据采集与分析系统对排气系统进行了自由状态下水平和垂直两个方向的测试和工况状态下的垂直方向的测试,得到了排气系统的主要固有频率和振型,为整车减振降噪水平的改善提供了的有效依据.     

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.     

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.     

磁悬浮轴承-转子系统的机电耦合动力学模型

对磁悬浮轴承 -刚性转子系统建立了完整的机电耦合动力学模型 ,其中除了人们通常所考虑的陀螺效应外 ,着重考虑和增加了推力磁轴承对转子横向振动的耦合效应和由于轴颈倾斜所引起的径向磁轴承之间的耦合效应 ,以及控制系统的电学微分方程和传感器与磁轴承非共点安装对系统性能所带来的耦合影响。该模型可用于五自由度磁悬浮轴承 -刚性转子系统的机电耦合动力学性能研究     

FDY型绕线机转子有限元分析及优化设计

利用大型有限元商用程序ANSYS对FDY型绕线机转子部分进行有限元建模,根据FDY型绕线机转子的工作转速范围及其基本动力特性,计算出其工作范围内所对应的振动频率.并利用转子支承都具有一定弹性的特点,通过改变转子支承刚度达到调整转子临界转速和振动形态的目的.     

非接触压电微马达的仿真与实验研究

提出了一种基于四区和八区2种激振方式的新型非接触压电微马达,并进行了振动模态的有限元数值模拟。利用ANSYS有限元软件对定子进行模态分析,并用激光测振仪对四区和八区2种激振方式下的定子进行位移扫频和振型测试,得出:最优驱动频率分别为34.4 kHz和46.3 kHz,相应的模态分别为B₂₁和B₂₂,二者结果吻合较好。对微马达的输出性能进行了实验研究,结果表明:三叶片和六叶片转子在八区最优模态激振下转子的转速约是四区的2倍。说明了增加定子的分区数不仅改变了定子的最优驱动频率而且能够明显提高转子的转速。而且当A-B间相位差从90°调谐到270°时,行波的传播方向发生了改变,从而实现了转子的换向。实验还表明,转子的正反转的转速基本一致。     

Dynamic Characteristics of Rotor System with a Slant Crack Based on Fractional Damping

The traditional modeling method of rotor system with a slant crack considers only integer-order calculus.However,the model of rotor system based on integer-order calculus can merely describe local characteristics,not historical dependent process.The occur of fractional order calculus just makes up for the deficiency in integer-order calculus.Therefore,a new dynamic model with a slant crack based on fractional damping is proposed.Here,the stiffness of rotor system with a slant crack is solved by zero stress intensity factor method.The proposed model is simulated by Runge-Kutta method and continued fraction Euler method.The influence of the fractional order,rotating speed,and crack depth on the dynamic characteristics of rotor system is discussed.The simulation results show that the ampli-tude of torsional excitation frequency increases significantly with the increase of the fractional order.With the increase of the rotating speed,the amplitude of first harmonic component becomes gradually larger,the amplitude of the second harmonic becomes smaller,while the amplitude of the other frequency components is almost invariant.The shaft orbit changes gradually from an internal 8-type shape to an ellipse-type shape without overlapping.With the increase of the slant crack depth,the amplitude of the transverse response frequency in the rotor system with a slant crack increases,and the amplitude in the second harmonic component also increases significantly.In addition,the torsional excitation frequency and other coupling frequency components also occur.The proposed model is further verified by the experiment.The valuable conclusion can provide an important guideline for the fault diagnosis of rotor system with a slant crack.     

基于混合优化算法的直升机旋翼转速优化控制

为了实现直升机巡航飞行时最经济运行,基于某型常规布局直升机,建立巡航阶段需用功率目标函数,以飞行稳定性与操纵安全性指标作为约束条件,利用遗传 序列二次规划( GA-SQP )混合优化算法,对直升机巡航阶段实现最低需用功率的最优旋翼转速进行优化求解。实验结果表明,该方法得到的最优旋翼转速能够有效降低整机需用功率,优化算法得出的最优转速曲线对巡航状态下旋翼转速的变化方向具有一定参考意义。     

Discussion on back-to-back two-stage centrifugal compressor compact design techniques

Design a small flow back-to-back two-stage centrifugal compressor in the aviation turbocharger, the compressor is compact structure, small axial length, light weighted. Stationary parts have a great influence on their overall performance decline. Therefore, the stationary part of the back-to-back two-stage centrifugal compressor should pay full attention to the diffuser, bend, return vane and volute design. Volute also impact downstream return vane, making the flow in circumferential direction is not uniformed, and several blade angle of attack is drastically changed in downstream of the volute with the airflow can not be rotated to required angle. Loading of high-pressure rotor blades change due to non-uniformed of flow in circumferential direction, which makes individual blade load distribution changed, and affected blade passage load decreased to reduce the capability of work, the tip low speed range increases.     

两自由度可控连杆机构系统机电耦联动态方程及其响应

针对控制电动机转子偏心时不均匀气隙磁场,分析其实际运行状态的机电耦合关系,建立以电机横振、扭振为节点位移的伺服电机单元,应用有限单元法建立含电机电磁参数和弹性连杆机构结构参数的系统非线性机电耦合动力学模型.通过对算例的数值计算,得出系统弹性振动固有频率和弹性位移响应随时间的变化曲线.结果表明,电机对机构弹性位移的影响不可忽视.文中的工作为此类系统进行动态优化设计提供一定理论依据,也为研究此系统动态特性打下一定的基础.     

基于实测冲击响应的转子碰摩力方向识别方法

提出了基于实测冲击响应的转子碰摩故障诊断特征提取方法.实验表明,该方法能够克服已有方法的缺点,可以准确提取信号中的冲击响应成分,且易于实际应用.在此基础上,提出了确定转子碰摩方向即静子碰摩位置的方法,该方法将转子轴心轨迹中的冲击响应成分投影到各初始相位不同的旋转坐标系中,进而以初始相位为参数,以投影能量最大化为目标进行寻优,从而确定碰摩力方向.并通过实验验证了方法的可行性.