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1.
压电振子的多维耦合振动(Ⅱ)——复合压电振子   总被引:4,自引:0,他引:4  
本文利用表观弹性法分析了复合压电振子的三维耦合振动的基频本振方式,得到了振子共振频率的很简单的解析表达式并由此计算了频率常数随振子尺寸变化的关系曲线。本文的计算结果同已发表的用有限元法计算的结果满意地符合。由于计算公式十分简单,因此共振频率的计算可以用微型计算器很快计算出来而无需用电子计算机,所以这种方法对工程设计和估算来说要比有限元法简便得多。 此外,还给出了有限长圆柱中“纵波”相速的频散公式,并与无限长圆柱中的公式进行了比较。 本方法也可用来计算其它复合压电振子的共振频率。  相似文献   
2.
In this paper,the fundamental modes of two- and three-dimensional coupled vibrations ofvarious piezoelectric ceramic vibrators,including the rectangular cross-sectional bar,the rectangularplate,the finite solid cylinder and hollow cylinder,are analyzed by using the apparent elasticitymethod,and some quite simple analytic formulae for the resonant frequencies of the above-men-tioned various piezoelectric vibrators are obtained,These formulae have been used to calculatethe variations of frequency constants with the geometric size of the vibrators,and the calculatedresults are in satisfactory agreement with the published experimental results and results calculatedby using various other methods,including the finite difference method,finite element method andRitz variational method.These formulae are quite simple,and the resonant frequencies or the geo-metric size of the vibrators can be rapidly calculated by using a scientific calculator instead of acomputer,so this method is more convenient for engineering  相似文献   
3.
本文介绍一种用于研究大型平面发射阵波束扫描特性的集合式相移开关波束扫描发射系统.这种系统利用的是等距阵相移开关波束扫描原理.它特别适用于研究各种不同尺寸、不同形状的阵元所构成的线阵或平面阵,在大角度扫描时的远场和近场的精细结构.波束扫描指向角,可以通过改变工作频率或阵元间距,控制到任意所需的指向.在不增加通道的情况下,适用于任意多个阵元所构成的等矩阵,包括在周期结构上随机分布所形成的随机阵. 本系统主要由集合式相移开关扫描波束形成器,多路功率放大器和宽频带多档输出匹配变压器组组成. 为了检验整个系统的性能,进行了初步实验.在水池中用脉冲法测量了扫描波束的指向性图.扫描波瓣的峰值位置θ_0的实验值和理论值符合得较好.  相似文献   
4.
A solution of the impedance wedge diffraction problem has been given by Malyuzhinets in Ref.[1].The key to the problem is to seek the solution of Malyuzhinets functional equations.However,how to go about getting the solution of the functional equations is not given in Ref.[1].A detailedprocess to get the solution of the functional equations is provided by using the infinite product theoryin Ref.[2],in which,however,there exist some errors and indistinct places. In this paper,these errors in Ref.[2] are corrected and another simpler method to obtain thesolution of the functional equations is also provided for the purpose of comparison.  相似文献   
5.
In this paper,a method of measuring the mechanical input impedance of the array element(longitudinal vibrating transducer)with square radiation head by using impulse sound tube is proposed.Theresonant frequencies determined from the measured mechanical input impedance are quite in agreementwith those obtained from the electrical admittance cycle diagram of the element.This indirectly shows thatthe proposed method is feasible.  相似文献   
6.
在海洋噪声测量及换能器校准测量中,都需要频率范围宽响应平直的水听器。这种水听器一般是采用劲度控制的压电元件制成的。 图1是我们所作的水听器的结构示意图。它是  相似文献   
7.
In this paper,under Kirchhoff's assumptions,a theory of the thin shell of radially-Polarizedpiezoelectric ceramic cylinder has been developed.Using the methods of Green's function and separa-tion of variables the scattering of a plane wave by the cylinder has been solved.The normal modeseries expressions of the velocity distribution of the surface of the cylinder and of the total soundfield have been obtained and from those an exact analytic expression of the transfer function of thecylinder as a sound receiver has been give.Arbitrary transient response of the cylinder can be cal-culated from the transfer function by using FFT. For PZT-5 piezoelectric ceramic cylinder,the transfer function,impulse response and step responsehave been calculated.The results show that the impulse response displays a typical minmum phasebehaviour and the cylindrical piezoelectric receiver belongs to the minimum phase system.Therefore,the phase spectrum of transfer function of the receiver can be reconstructed from its amplit  相似文献   
8.
In this paper,a simple method deriving the transfer function of a spherical piezoelectric transducerhas been given.Transient responses have been obtained from the analytical expression of transferfunction by using FFT.Calculated results show that the impulse response of the spherical piezoelectrictransducer also exhibits the minimum phase behaviour and so the phase spectrum of its transfer func-tion can be reconstructed from the amplitude spectrum by using the Hilbert transform,the reconstruct-ed phase spectrum is in good agreement with that calculated from the analytical expression of transferfunction directly. Based on above-mentioned results,the phase spectrum of transfer function of a F42-c spherical pic-zoelectric transducer has been reconstructed from the measured values of its amplitude spectrum for thefirst time.The reconstructed phase spectrum is basically consistent with the measured values of phasespectrum. In addition,the impulse response and step response of F42-c spherical piezoelectric tra  相似文献   
9.
This paper presents an analysis of the three-dimensional coupled vibrations of a compositepiezoelectric vibrator by using the apparent elasticity method. A very simple analytic formula for the resonant frequency of the vibrator is obtained and withit the variation of the frequency constant with the geometric size of the vibrator is calculated. A satisfactory agreement is obtained as compared with the published results calculated by thefinite element method. Because the formula is quite simple the resonant frequency of the vibrator can be quickly cal-culated by using a scientific calculator,without having to use a computer,and so this method ismore convenient than the finite element method for engineeing design and estirmation. In addition,a dispersion relation of the phase velocity of "longitudinal"waves in the finiteisotropic solid cylinder is given and a comparison between this relation and those in an infinitecylinder is made. This method may also be used to calculate the resonant frequencies of other  相似文献   
10.
本文提出了一种新的相位重现或信号恢复的迭代方法。在假定系统的传递函数的相位(或信号的傅里叶交换的相位)为非负或非正,系统的脉冲响应或时域信号的支集为有限的条件下,以任意线性相位作为初始估计,借助于FFT算法从已知振幅谱反复迭代得到了满意的相位重现和信号恢复。讨论了控制收敛速度的方法以及本方法在任意形状的轴对称压电接收器相位重现中的应用。  相似文献   
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