微超声振动细胞切割系统中变幅杆的分析与设计

针对细胞微超声振动切割系统对超声变幅杆的要求,将等截面圆柱形阶梯变幅杆的一端替换成圆锥形变幅杆构成一种复合圆锥阶梯形变幅杆。由任意变截面杆纵向振动的波动方程出发,推导了复合圆锥阶梯形变幅杆的基本理论参量,设计了超声变幅杆的基本结构,给出其制造尺寸。并应用有限元法对变幅杆进行了模态分析,得到了共振频率和位移节点等重要参数。     

纵—扭复合振动模式超声变幅杆研究

本文对窄端带有均匀截面直棒的指数型纵-扭复合振动模式超声变幅杆进行了理论及实验研究,推出了该复合模式变幅杆纵向振动及扭转振动的共振频率方程。为了克服同一变幅杆纵向与扭转振动很难实现同频共振的问题,提出了一种通过改变指数型变幅杆的截面变化规律而实现改变纵向及扭转振动传播速度的方法。通过合理选择指数变幅杆的截面半径减缩系数(即参数β),实现了纵-扭复合变幅杆纵向振动与扭转振动的同频共振。实测结果表明,共振频率的理论值与测试值基本一致,变幅杆纵向及扭转振动共振频率的测试值也比较符合。该变幅杆具有比较高的位移放大系数。可望应用于超声加工、超声疲劳实验及超声焊接等功率超声技术中。     

新型齿轮超声加工纵向振动系统的设计

在传统的齿轮纵向振动系统中,齿轮与变幅杆耦合处振幅较小,导致齿轮端面输出振幅偏小,满足不了齿轮超声加工的要求.基于非谐振设计理论和全谐设计理论,设计了一种新型齿轮纵向振动系统,该振动系统由齿轮与圆柱杆耦合振动单元、换能器、半波长圆锥形变幅杆组成,齿轮与变幅杆耦合处振幅较大,增大了齿轮端面的输出振幅.圆锥变幅杆形状参数固定时,齿轮分度圆直径和圆柱杆直径对齿轮端面的输出振幅没有影响,减小圆锥变幅杆小端直径可以增大齿轮端面的输出振幅.通过有限元分析和谐振特性实验验证这种新设计方法的可行性.研究结果为齿轮振动系统提供了一种新的设计方法,对齿轮超声加工工艺的工程应用具有重要意义.     

B8 几种扭振复合超声变幅杆的研究

Ｂ８几种扭振复合超声变幅杆的研究阮世勋（佛山大学广东佛山·５２８０００）本文从扭振方程出发，导出两端是圆柱形段中间为变截面段的复合型扭振超声变幅杆的频率方程和参数计算通式。这些通式适用于（Ⅰ）ｌ１＝ｌ２≠０；（Ⅱ）ｌ１＝０，ｌ３≠０；（Ⅲ）ｌ１≠０，...     

阶梯形变幅杆的频率特性分析

计算了圆柱截面阶梯形变幅杆的一阶到六阶纵振动模式的谐振频率,较系统地分析研究了带与不带过渡段的阶梯杆之谐振频率随其粗细段长度比和直径比的变化规律,得到了一些新结果。用两种方法计算谐振频率:一种是求解一维近似解析频率方程,计算程序用MATLAB编制。另一种是用有限元仿真数值计算,利用ANSYS软件,且适合对于任意材料和几何参数的圆截面阶梯杆的任意阶谐振频率的计算。有限元计算与一维近似理论计算得到的频率的变化趋势基本一致。所给频率变化趋势对于变幅杆的设计和加工都能提供参考。在相当大的阶梯杆几何参数空间内,一阶谐振频率随变幅杆粗段与过渡段长度而相应减小。对于实测频率比所期望值高的变幅杆进行频率调整时可以利用上述性质。     

抗性负载超声复合变幅杆振动特性研究

在抗性负载情况下,利用纵振型变幅杆等效四端网络,对频率方程和放大系数进行了研究,并推导出圆锥过渡段和指数过渡段阶梯形复合变幅杆频率方程和放大系数的一般公式;并通过MATLAB编程,分别绘制了共振频率及放大系数随负载变化的曲线图。这将对超声复合变幅杆的设计和应用提供一定的理论依据。     

内柱孔和内锥孔圆柱形变幅杆

激光和水射流是对陶瓷等易碎材料进行辅助打孔的传统方法,其设备存在大而复杂等缺点。加工陶瓷等易碎材料时,利用超声振动的带孔变幅杆的设备比起传统的利用激光和水射流的的设备更简易和小型化,因此,超声加工受到了人们的重视。文章对中心孔分别为柱形和锥形、外形为圆柱形的超声杆件,基于解析法推导了这两种孔型变幅杆的频率方程及性能参数表达式,分析了不同参量对其性能参数的影响,并利用有限元法计算了在谐振状态下这两种变幅杆的应力及振动位移沿轴向分布的规律。结果表明,在相同谐振频率及面积系数下,带孔变幅杆的放大系数大于实心圆柱杆的放大系数;锥形孔变幅杆的放大系数小于柱形孔变幅杆的放大系数,但前者应力曲线光滑且应力极大值较小。     

抛物线型超声变幅杆的探讨

提出了一种新型的变幅杆-抛物线型变幅杆。根据变截面杆纵向振动的波动方程,推导出抛物线型变幅杆的频率方程、节点位置方程、放大系数、形状因数等参数,并用有限元软件ANSYS分析了几个半波长抛物线型变幅杆,得出共振频率。结果表明:抛物线型变幅杆在保持圆锥变幅杆形状因数较大的优点上,放大系数有所提高;有限元分析结果与理论值符合的较好。     

一端带有圆柱杆的复合纵振超声变幅杆的简明设计理论

对一端带有圆柱杆的各种复合型纵振超声变幅杆，用“替代法”（在变幅杆的两端面处，利用机械阻抗相等的办法），求出其谐振频率方程，使设计简单化。为便于应用，本文求出了此种类型的多种复合型变幅杆的谐振频率方程。     

大尺寸矩形截面幂函数复合变幅杆的研究

利用传输矩阵法,计算得到了幂函数复合变幅杆一维纵振动的频率方程,并在此基础上运用表观弹性法分析了大尺寸矩形截面幂函数复合变幅杆,得到了考虑横向耦合振动后的谐振频率方程,最后利用有限元软件ANSYS对三组变幅杆进行了模态分析。结果表明：变幅杆谐振频率的计算值与模拟值符合得很好,与一维理论相比,考虑横向耦合振动的二维理论具有更高的精确度。     

大功率超声清洗机研制中的一些技术问题

本文介绍了微机控制的大功率超声清洗机研制的一些技术问题，探索了单片机在功率超声中的应用，提出了大功率超声振动子的一种新的设计方法，解决了一些影响振动子性能的关键问题，对于楔形工具头的超声振动子平均振幅的测量以及与同类机型的比较成为可能，文中还给出了部分比较曲线，实际测量证明，本文所述的系统比同类进口机平均振幅提高一倍以上，对工件的清效果明显优于进口机。     

FATIGUE CRACK GROWTH UNDER ULTRASONIC FATIGUE LOADING

Abstract— In this paper, a stress and modal analysis of an ultrasonic vibration system consisting of a notched specimen and one or two amplifying horns have been performed by using 3D finite element calculations. The stress intensity factors in ultrasonic fatigue crack propagation are evaluated by means of displacement and energy approaches. The particular advantages as well as limitations of the two approaches are briefly discussed. Two types of ultrasonic fatigue loading, with a different stress ratio, are exerted on the specimen. From a comparison of the results a conclusion is formed that the energy approach is more accurate; it also has a wide range of practicality in engineering industries.     

High-frequency, silicon-based ultrasonic nozzles using multiple Fourier horns

This paper presents the design, simulation, and characterization of microfabricated 0.5 MHz, silicon-based, ultrasonic nozzles. Each nozzle is made of a piezoelectric drive section and a silicon resonator consisting of multiple Fourier horns, each with half wavelength design and twice amplitude magnification. Results of finite element three-dimensional (3-D) simulation using a commercial program predicted existence of one resonant frequency of pure longitudinal vibration. Both impedance analysis and measurement of longitudinal vibration confirmed the simulation results with one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical values of 2(n). Using this design, very high vibration amplitude gain at the nozzle tip can be achieved with no reduction in the tip cross-sectional area for contact of liquid to be atomized. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.     

A note on finite dynamic deformation of concentric cylinders

This paper considers the finite amplitude wave propagation which results when a compound cylinder consisting of two concentric, isotropic compressible cylinders is subjected to a sudden spatially uniform application of pressure at the inner cylinder's surface. The two cylinders each have different constitutive equations and are bonded together at the interfacial radius. Plane strain deformation is assumed and results are presented here for the Gaussian strain-energy function.     

带过渡段阶梯形变幅杆的有限元分析

对几组不同变幅比带不同过渡段的阶梯形变幅杆进行了有限元分析,获得了阶梯形变幅杆特性随过渡段形状和尺寸变化的一些规律。利用有限元软件ANSYS算出了每个变幅杆的纵振动模式谐振频率。并用其后处理功能得出了粗细端面的相对位移,由此计算振幅放大系数,得到的结果与已有的关于阶梯形变幅杆的理论以及实验结果符合得较好,计算出的谐振频率与实际测量值也较好地相符。文中还利用该软件计算了变幅杆粗细端分界面上的应力及其分布,数据表明过渡段可以显著改善粗细分界面上的应力集中。最后对导波理论和有限元分析方法的结果做了初步比较,两者亦符合较好。     

Design of highly uniform spool and bar horns for ultrasonic bonding

Although the groove and slot have been widely utilized for horn design to achieve high uniformity, their effects on uniformity have not been analyzed thoroughly. In this work, spool and bar horns for ultrasonic bonding are designed in a systematic way using the design of experiments (DOE) to achieve high amplitude uniformity of the horn. Three-dimensional modal analysis is conducted to predict the natural frequency, amplitude, and stress of the horns, and the DOE is employed to analyze the effects of the groove and slot on the amplitude uniformity. The design equations are formulated to determine the optimum dimensions of the groove and slot, and the uniformity is found to be influenced most significantly by the groove depth and slot width. Displacements of the spool and bar horns were measured using a laser Doppler vibrometer (LDV), and the predicted results are in good agreement with the experimental data.     

阻性负载超声变幅杆振动特性研究

在纵振型变幅杆等效电路的基础上,研究了三类负载超声变幅杆的共振频率与放大系数。得到了阻性负载时,变幅杆频率方程与放大系数的计算式;分别绘制了共振频率及放大系数随负载变化的曲线图,并给出了分析。这将有助于超声变幅杆的研究和设计。