黏弹性阻尼减振技术及其在梁类结构中的应用

对因结构特点或工作环境所限不能采用主动振动控制的结构,采用阻尼被动振动控制具有简单易行且可靠的优势.在对黏弹性阻尼材料黏弹特性进行分析的基础上,利用其耗能原理,建立约束阻尼层梁的动态有限元模型,并基于小变形线弹性理论对阻尼夹芯梁进行ABAQUS有限元仿真模拟.模拟结果表明,约束阻尼减振比自由阻尼减振更适合于梁类结构,合理设计阻尼层厚度可以在较短时间内消耗掉输入的振动能量,使结构振动减弱甚至趋于静止.所设计的环形夹芯约束层可以解决梁因中间添加较软黏弹阻尼层而造成的层间大变形错位以及刚度的削弱.     

称量轨式不断轨轨道衡的理论、生产与应用

本文结合称量轨式不断轨动、静态电子轨道衡，阐明了重复性好和计量准确两点理论；说明了生产一体化大型称量轨，独立、多通道电路，功能软件包和钢混结构道床的情况；介绍了几个客户的验收数据，理论验证数据和使用情况。     

A pendulum-like tuned vibration absorber and its application to a multi-mode system

This paper presents the design of a pendulum-like adaptive tuned vibration absorber (ATVA) and its application to a multi-mode system. The natural frequency of the pendulum-like ATVA can be adjusted in real time by adjusting its geometric parameters. The principle and the dynamic property of the ATVA are theoretically analyzed. Based on the analysis, a prototype of the ATVA is proposed and developed. Simulations are carried out to predict the effectiveness of the ATVA when applied to the multi-mode system. The simulated results are verified by experimental studies, which are conducted on a multi-mode platform that comprises mass, isolator, and a flexible base. The results indicate that the ATVA installed on an optimized location in the system can effectively reduce vibration over a broad frequency range and can perform better than a tuned vibration absorber.     

并联运动振动筛的筛分运动规律及其轨迹的研究

传统振动筛筛面轨迹为直线、圆、椭圆,由于轨迹单一,会出现堵孔现象,筛分效率不高.文中论证了用并联运动振动筛可实现理想的筛分运动,其筛面轨迹为空间复杂曲线,沿筛面长度方向各点的运动轨迹不断变化,且筛面各点均做异幅运动,物料在筛箱中做空间三维运动,具有良好的透筛环境和筛分效率;还讨论了机构构件尺寸和主动输入相位初始角对筛面运动轨迹的影响,为进行主机构结构优化设计以实现最佳的筛分效果奠定了基础.     

Development of velocity sensor with high frequency band and its application to a vibration isolate table

The vibration sensors are widely used in the field of vibration control and measurement. In applying the modern control theory to anti-vibration controlled objects, the state variables both the velocity and displacement become useful signals. Then, the velocity sensor in comparison with the acceleration sensor, which is in generally used, is very useful. However, its frequency band is limited by high frequency resonance due to the electrical stiffness. If the velocity sensor having flat frequency band is developed, this sensor becomes easy to handle not only in the control field but also in the measurement filed. Then, this paper shows that the inverse notch filter, which is inserted in the closed loop, flattens out the frequency response originally having high frequency resonance. Firstly, the block diagram of the velocity sensor as a closed system is shown. Its sensitivity, the low break point frequency, and the high frequency resonance are formulated. Secondly, the gain and phase margins are calculated and we try to improve the frequency response based on these indices. Finally, the application of improved velocity sensor to an anti-vibration apparatus is shown.     

振动切削技术特点及其应用状况

振动切削加工是先进制造方法的重要组成部分,是一种优于普通切削的新技术;通过普通切削与振动切削的对比,分析了振动切削的特点及工艺效果,工艺效果主要表现为瞬间切削力增大,零件表面质量的提高,最后论述了振动切削加工技术在工业中的具体应用.     

Multi-scale simulation method with coupled finite/discrete element model and its application

The existing research on continuous structure is usually analyzed with finite element method (FEM) and granular medium with discrete element method (DEM), but there are few researches on the coupling interaction between continuous structure and discrete medium. To the issue of this coupling interaction, a multi-scale simulation method with coupled finite/discrete element model is put forward, in their respective domains of discrete and finite elements, the nodes follow force law and motion law of their own method, and on the their interaction interface, the touch type between discrete and finite elements is distinguished as two types: full touch and partial touch, the interaction force between them is calculated with linear elastic model. For full touch, the contact force is proportional to the overlap distance between discrete element and finite element patch. For partial touch, first the finite element patch is extended on all sides indefinitely to be a complete plane, the full contact force can be obtained with the touch type between discrete element and plane being viewed as full touch, then the full overlap area between them and the actual overlap area between discrete element and finite element patch are computed, the actual contact force is obtained by scaling the full contact force with a factor which is determined by the ratio of the actual overlap area to the full overlap area. The contact force is equivalent to the finite element nodes and the force and displacement on the nodes can be computed, so the ideal simulation results can be got. This method has been used to simulate the cutter disk of the earth pressure balance shield machine (EPBSM) made in North Heavy Industry (NHI) with its excavation diameter of 6.28 m cutting and digging the sandy clay layer. The simulation results show that as the gradual increase of excavating depth of the cutter head, the maximum stress occurs at the roots of cutters on the cutter head, while for the soil, the largest stress is distributed at the region which directl     

Instability and vibration of a rotating Timoshenko beam with precone

A rotating blade with a precone angle is usually designed, but little literature has investigated the effect of the precone angle on vibration. This paper investigates divergence instability and vibration of a rotating Timoshenko beam with precone and pitch angles. It uses Hamilton's principle to derive the coupled governing differential equations and boundary conditions for a rotating Timoshenko beam. Analytical solution of an inextensional Timoshenko beam without taking into account the Coriolis force effect can be derived. Some simple relations among the parameters of rotating Timoshenko beams are revealed. Based on these relations, one can predict the natural frequencies and parameters of other systems from those of known systems. Moreover, the mechanism of divergence instability (tension buckling) is investigated. Finally, the effects of the parameters on natural frequencies, and the phenomenon of divergence instability are investigated.     

振动切削技术特点及其应用研究

通过普通切削与振动切削的对比,分析了振动切削的特点及工艺效果,工艺效果主要表现为瞬间切削力增大,零件表面质量的提高;最后阐述了振动切削加工技术在工业中的具体应用。     

A vibration analysis method based on hybrid techniques and its application to rotating machinery

Vibration-based condition monitoring and fault diagnosis technique is a most effective approach to maintain the safe and reliable operation of rotating machinery. Unfortunately, the vibration signal always exhibits non-linear and non-stationary characteristics, which makes vibration signal analysis and fault feature extraction very difficult. To extract the significant fault features, a vibration analysis method based on hybrid techniques is proposed in this paper. Firstly, the raw signals are decomposed into a few product functions (PFs) using local mean decomposition (LMD), and meanwhile instantaneous frequency and instantaneous amplitude also are obtained. Subsequently, Fourier transform is performed on the derived PFs, and then, according to the spectra features, the useful PFs are selected to reconstruct the purified vibration signals. Lastly, several different fault features are fused to illustrate the operating state of the machinery. The experimental results show that the proposed method can accurately extract machine fault features, which proves that the combined application of LMD and other signal processing techniques is a successful scheme for the machine vibration analysis.     

Pro/E环境中的弹簧装配研究及应用

Pro/E环境中进行弹簧装配,弹簧的自由高度和安装高度不同,安装问题一直不能得到很好解决。通过对弹簧模型进行设定和二次开发,装配过程的挠性关系设定,使弹簧长度能够随着安装高度或工作高度的改变而自动改变,完成弹簧适合的装配,为后续的干涉检查、运动仿真、应力分析等工作奠定了基础。     

Nonlinear bending and free vibration analyses of metal-ceramic functionally graded plates by 2-D natural element method

Journal of Mechanical Science and Technology - Metal-ceramic functionally graded materials (FGMs) have attracted much attention in the recent years thanks to their excellent properties. Accordingly...     

基于SVD降噪的机械振动信号经验模式分解及其应用

提出了1种基于奇异值分解降噪的振动信号经验模式分解方法,利用该法对原始振动信号进行相空间重构和奇异值分解,并根据奇异值降噪,再利用经验模式分解法提取降噪后振动信号的基本模式分量,对滤波前和滤波后振动信号进行经验模式分解分析。分析结果表明：奇异值分解能有效地提高信噪比,突出原始振动信号的特征,使降噪后振动信号分解出的基本模式分量具有更明确的物理意义,有利于对柴油机进行精确诊断。     

一种简单高效的有限元网格优化算法及应用

针对三维有限元实体模型中网格形状优化的问题,提出了一种新的网格优化算法,并编制了基于这种算法的网格优化程序。该算法的优点是计算简单、节省机时,且网格优化效率较高,性能较为可靠。     

Modeling and analysis of the vibration behavior of a shape memory alloy beam

Shape memory alloys have a high potential for passive isolation of vibrations as well as capability of being used as an active vibration isolation system for their shape memory behavior, i.e. having hysteresis along with superelastic behavior. Study of this behavior necessitates recognition of distinct specifications of this alloy and also presentation of a suitable and simple mathematical model. In this paper, a mathematical model based on Auricchio model, considering asymmetry in tension and compression and also temperature effects on hysteresis at superelastic conditions has been presented. Finally, dynamical behavior of a NiTi beam under free vibration as well as application of sinusoidal and impulse loads upon free–clamped and also simply supported conditions have been analyzed.     

多模型自适应广义预测控制及其在电厂汽温系统中的应用仿真

针对火电厂变负荷机组汽温系统动态特性的时变大迟延特点,首先给出了广义预测控制律的简化算法,在此基础上提出多模型广义预测控制方案。分析了多固定模型的选取问题,给出了在特定工况下的模型选择依据。仿真结果证实了算法的有效性。     

四边固支矩形薄板固有振动的理论计算和有限元分析

基于理论计算有限元方法分析了四边固支矩形板结构的自由振动问题,求得了四边固支矩形板的振动固有频率和振型。利用双向梁函数构造了四边固支矩形板的振型函数,并根据位移变分原理求得了矩形板的固有振动特性。在板单元理论的基础上,利用有限元法推导了薄板振动的质量矩阵和刚度矩阵。由于工程实际中只关心板结构振动的横向位移幅值,利用静力凝聚法将质量矩阵和刚度矩阵中转动自由度上的质量和刚度凝聚到横向振动自由度上,以达到降低模型阶目的,为板结构振动主动控制奠定基础。     

数字加速度传感器ADXL210在轨检仪中的应用

介绍了一种轨道检测仪及其重要传感器数字加速度传感器ADXL210的工作原理、功能、应用,并给出了ADXL210与MCS－51单片机的接口硬件电路和软件程序。     

主被动隔振法在金刚石刀具研磨压力控制中的应用

主被动隔振能够有效改善系统全频带隔振能力,有助于金刚石刀具研磨过程中稳定控制刀具刃口所受到的研磨压力.在应用主被动隔振法控制刀具研磨压力时,需要根据刀具刃磨机床进给轴的控制能力,合理设计柔性调压平台Z向支承刚度,通过调压平台的支承刚度抑制高频振动,同时还要确保位移控制量的输出频率和调压平台固有频率之间的匹配关系,通过主动控制削弱调压平台的谐振峰,以达到稳定刀具研磨压力的目的.