共查询到19条相似文献,搜索用时 155 毫秒
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为实现在纵向单激励超声振动输入条件下获得纵扭谐振输出,提出一种基于声波传播理论为基础设计阶梯型变幅杆,并在其小端增加沿中心轴均布6斜槽的圆环传振杆的方案:首先数值计算进行理论设计,然后使用有限元进行分析修正,最后确定变幅杆尺寸。结果表明:理论设计谐振频率20kHz,仿真分析在19457Hz时变幅杆能够实现纵扭谐振;根据仿真结果制作变幅杆,阻抗测试结果谐振频率为19884Hz,与理论值、仿真值误差较小;在输入端加载幅值为5μm的纵向单激励超声振动,测试输出端截面圆周上任意一点,其切向和纵向振幅分别为12.7μm和8.5μm,表明变幅杆实现了纵扭谐振且振幅增强。 相似文献
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用振动激励信号做频率电压变换的倒相触发信号,可以从激光二极管自混合干涉信号还原扬声器谐振时的振动波形,输出信号的振幅与扬声器的振幅成正比. 用正弦波、方波和三角波信号分别激励扬声器,利用自制的激光二极管自混合干涉实验仪观测了的扬声器振动特性,测量了扬声器的谐振曲线. 相似文献
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模式转换型超声塑焊振动系统的设计 总被引:4,自引:0,他引:4
基于弯曲振动理论和耦合振动理论,设计了一种新型大尺寸筒形超声塑焊振动系统。该振动系统由纵向振动换能器及变幅杆、弯曲振动金属圆盘和耦合振动圆筒四部分组成。换能器和变幅杆的纵向振动驱动圆盘的二次弯曲模式振动,圆盘的二次弯曲模式振动激励圆筒的纵向模式振动,实现了工具头在较高频率下谐振。实验结果表明,振动系统的测试频率与计算频率比较符合,在大信号下测试的纵-弯-纵振动模式转换效果很好。研究结果为高频大尺寸超声焊接系统的设计提供了思路。 相似文献
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研究了人体仰卧姿态下,振动的幅值大小和输入方向对人体头部和胸部振动传递率的影响。分别采用频率范围为0.5~20 Hz,振动幅值为0.2~0.8 m/s2 r.m.s.的纵向、横向和垂直单轴随机振动激励,测量了12名男性被试者自振源至头部和胸部的振动传递特性。结果表明,人体头部和胸部振动传递率的共振频率在纵向方向上大约为4 Hz,在横向方向上大约为2.4 Hz,而在垂直方向上头部和胸部传递率的共振频率并不相同。在纵向激励下,仰卧人体各部位振动传递率随振幅变化而表现出的非线性特征最为明显。 相似文献
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用Laplace变换法求解端点系有集中质量的弹性杆的振动问题 总被引:6,自引:2,他引:4
用Laplace变换法求解了一端为齐次边界条件,另一端系有集中质量的弹性杆的纵振动问题,推广了相关文献的结果。 相似文献
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二维振动方向变换器集功率合成和二维超声输出的功能于一体,在功率超声技术中具有重要的应用价值。然而,对于二维振动方向变换器的设计分析只有一种较为复杂的波动方程法。为此,本文研究了二维振动方向变换器的另外一种简明的设计分析方法——等效电路法。通过引入二维机械耦合系数和纵向力转换系数,利用力电类比原理建立了二维振动方向变换器的同相及反相二维耦合振动的统一等效电路模型。利用本文提出的设计方法,计算了两种不同材料的二维振动方向变换器的谐振频率,与有限元计算结果及实验测试结果一致,为该类超声振动系统的工程应用提供了一种简洁直观的设计分析方法。 相似文献
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T. Pritz 《Journal of sound and vibration》1982,85(2):151-167
The dynamic strain of a viscoelastic rod excited into longitudinal simple harmonic vibration, a constant amplitude displacement being maintained by a shaker at one end and a mass terminating the other end, is theoretically investigated in this paper. The general equation of the strain distribution in the rod is derived by solving the one-dimensional wave equation. It is shown that the strain in the rod is the largest at the excited end, at the antiresonant frequencies. Simplified approximate equations are derived for the low loss case to calculate the largest strain in the rod with knowledge of the loss factor. 相似文献
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The stability of the higher output power with high-quality beams is very important parameter in material processing. This paper presents using the S parameter and Gauss beam parameters matching to design efficient resonant cavity of two-rod Nd:YAG. The fundamental mode beam radius in rod, fundamental mode beam radius on the mirror, beam quality factor, and the value of the degree of the symmetry of the TEM00 mode volume as a function of the between neighbor rods distance, laser rod end face to mirror distance, and input power are simulated. The design method of resonant cavity is illustrated and compared with previously published experimental measurements for different pump power and the length of the cavity parameters and a good agreement has been found. 相似文献
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LIN Shuyu ZHANG Fucheng 《声学学报:英文版》1993,(4)
Based on the theory of coupling vibration and flexural vibration of thin rod of rectangular cross section, the fiexural vibration of rectangular thin plate was studied. The frequency equation was derived under the condition of freeboundaries. The normal modes and the relation between the normal modes and the resonant frequency were obtained. Experiments showed that the calculated resonant frequencies agree well with the measured results, and the rectangular thin plate in flexural vibration has abundant resonant frequencies. The radiator of flexural vibration used in ultrasonic cleaning and other techniques has the advantages of large acoustic radiating area, uniform acoustic field and easy adjustment of resonant frequencies, proving that it is a promising ultrasonic source. 相似文献
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I.V. ANDRIANOVV.V. DANISHEVS'KYY 《Journal of sound and vibration》2002,249(3):465-481
An asymptotic approach for determining periodic solutions of non-linear vibration problems of continuous structures (such as rods, beams, plates, etc.) is proposed. Starting with the well-known perturbation technique, the independent displacement and frequency is expanded in a power series of a natural small parameter. It leads to infinite systems of interconnected non-linear algebraic equations governing the relationships between modes, amplitudes and frequencies. A non-trivial asymptotic technique, based on the introduction of an artificial small parameter is used to solve the equations. An advantage of the procedure is the possibility to take into account a number of vibration modes. As examples, free longitudinal vibrations of a rod and lateral vibrations of a beam under cubically non-linear restoring force are considered. Resonance interactions between different modes are investigated and asymptotic formulae for corresponding backbone curves are derived. 相似文献
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G.L. Anderson 《Journal of sound and vibration》1978,57(3):403-412
The derivation of the equations of motion is given for a system consisting of two identical parallel cantilevers joined by a rigid connector at their free ends. Elementary beam theory is employed, and it is observed that the longitudinal and flexural deformations of the system are coupled through the boundary conditions but not through the differential equations. The associated free vibration problem is solved, and it is shown that the frequency determinant can be factored, yielding two independent frequency equations. One of these corresponds to the pure, free longitudinal motion of a pair of rods connected by a rigid body at their tips (both rods being equally stretched or compressed simultaneously), whereas the second and more complicated frequency equation is pertinent for the system undergoing flexural deformations in both rods, stretching in one rod, and compression in the other. This latter frequency equation is solved numerically, and the variations of the first six natural frequencies with connector thickness and length parameters are displayed graphically. Two orthogonality conditions for the eigenfunctions are derived, and a relatively simple form for the normalizing factor is presented. 相似文献
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With the advantages of transmitting energy from multiple directions to one direction and transforming vibration from one source to multiple directions, the two-dimensional vibra?tion direction converter has important applications in power ultrasonic technology. However, for the complexity of using the wave equation to design and analysis the two-dimensional vibration direction converter, a concise equivalent circuit for the converter is investigated. By introducing the two-dimensional mechanical coupling coefficient and the longitudinal force transform coef?ficient, and using the electromechanical analogy principle, the equivalent circuit and resonance frequency equation of the two-dimensional vibration direction converter vibrating in anti-phase and in-phase two-dimensional coupled vibration are deduced. The resonance frequencies of the vibration direction converters of two different materials are calculated by using the proposed frequency equation, which are in agreement with the results from the finite element method and the experimental test. It provides a concise method for the design and applications of such ultrasonic vibration system. 相似文献
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The transverse vibrations of a plane system of rods is considered. The analysis of internal resonance in the system is a primary purpose of the paper. The internal resonance analyzed has an autoparametric nature. The couplings of the elements of the system through internal longitudinal forces, which are transverse forces at the ends of neighbouring rods, are taken into account. The amplitudes of the vibrations in the stationary states of internal resonance are investigated. Non-linear terms appear in the equations of motion. These terms are non-linear damping and non-linear inertia, and have a geometrical nature. The approximate method of calculation gives formulae for the vibration amplitudes of the rods. Plots of the amplitudes against frequency are presented. The stabilizing effect of masses placed at the articulated joints of the system is shown. The influences of the inertia and damping values on the character of the curves is considered. The results obtained are of a qualitative character. 相似文献
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本文理论研究了近红外波段硅基三角晶格光子晶体环形微腔的光场局域特性,通过将微腔在空间周期性排列组成耦合腔光波导,研究了多个导带区域内光束传输时的群速度,最大和最小值分别为0.0028c和0.00028c.将环形微腔在垂直于光传输方向上进行交错排列,通过改变相邻微腔之间的耦合区域,可以大幅降低多频段范围内光束在耦合腔波导中传输时群速度之间的差异,并提高部分频段的透过率数值.在不改变介质柱半径条件下,通过去掉三角晶格光子晶体中距中心介质柱距离分别为2a和√3a的六个介质柱构成了两种微腔,研究了两种微腔所支持的谐振波长之间的差异,在此基础上构造了两种耦合腔波导,进而将这两种耦合腔光波导与W1型输入/输出波导相连,最终实现了在多个不同频率范围内降低群速度的同时实现频段选择和频段分束功能,其导模群速度可降低到0.00047c. 相似文献
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Vibration data are required for condition monitoring in machinery, and can only be collected indirectly after transferring through rods, shells, rotating shafts or other components in many engineering applications. Investigation on the transfer characteristics of vibration in these components is very helpful to guarantee the efficiency of the data collected indirectly. Here, the longitudinal wave propagation in a rod with variable cross-section is investigated. First, the equations of motion are established for the rod based upon the elementary wave theory, the Love theory and the Mindlin–Herrmann theory. Second, the transfer matrix method is employed to explore the propagation characteristics of the rod from the derived equations of motion. Finally, two kinds of rods with the cross-sections varying in the exponential and the polynomial forms are used to illustrate the analytical predictions of the propagation characteristics of the longitudinal wave, which are compared with the results from the finite element analysis (FEA) method. It is shown that Poisson's effect or the shear deformation plays a very important role in the longitudinal wave propagation in the rod and can widen the rod's stop band moderately. Moreover, the cut-off frequency of the rod is unconcerned with the variation form of the cross-section, but dependent on the area ratio between both the ends of the rod, even though Poisson's effect or shear deformation is included. 相似文献