压电弹性层合梁-板结构中SH波的传播

建立了压电层合梁-板结构的压电-弹性动力学基本方程式，在给定压电层合梁-板结构形式和波传播方向的情况下，对基本方程式进行了简化；利用连续性条件和边界条件，建立了波传播的特征方程式，并对波动方程式进行求解；得到了前三阶频散关系曲线。通过实例数值计算，讨论了弹性层、压电层的厚度比与频散关系的影响，得出了SH波在压电层合梁-板结构中传播的基本特性。     

功能梯度压电层/压磁半空间结构中SH波传播

分析功能梯度压电层/压磁半空间结构中SH波传播特性。功能梯度压电材料沿x2方向按指数形式变化,电学边界条件分为电学短路及开路,基于推导的频散方程数值分析功能梯度压电材料的梯度系数、覆层厚度及边界条件对频散关系影响。研究成果可为研制、设计高性能声波器件提供理论参考。     

压电空心圆柱体中的周向SH波

基于三维线性压电弹性理论,采用一种正交多项式级数方法研究了轴向极化、电开路时正交各向异性压电空心圆柱中的周向SH波。把位移和电势展开成勒让德多项式级数,引入点确定的材料常数以解决边界条件,最后把问题的解简化为一个特征值问题。计算了不同径厚比下FZT-4管道周向SH的波频散曲线和电势分布。讨论了压电的影响。     

压电拼接电磁复合材料中裂纹对SH波的散射

利用积分变换及奇异积分方程技术研究电磁复合材料底层处裂纹对SH波散射问题。假定裂纹面的边界条件为电渗透性,通过Fourier余弦变化将问题转化为对偶积分方程,并利用Copson方法将对偶积分方程转化为第二类Fredholm积分方程求解。给出标准动应力强度因子表达式;通过数值计算分析裂纹长度、裂纹到界面距离、入射波频率及入射角对标准动应力强度因子影响。     

压电功能梯度材料中的SH表面波

为了提高声表面波器件的性能,压电功能梯度材料(FGPM)被广泛应用在声表面波(SAW)技术上,因此,压电功能梯度材料中表面波的传播特性研究变得十分重要.研究了压电功能梯度材料中SH(Shear Horizontal)波的传播特性.对于材料特性沿厚度方向为线性函数、二次函数和三次函数变化的三种形式,基于压电-弹性理论,得...     

各向异性弹性层中SH波传播的边界元方法

本文利用坐标变换下的映象法求出了底部为刚性边界的各向异性弹性层中SH波传播问题的格林函数,并由此建立了求解分层介质问题的边界元方法。文中给出了在稳态线荷载作用下带有圆孔的弹性层中反应的计算实例。     

Love波在电磁弹性多层结构中的频散特性

在电磁弹性多层结构模型的基础上, 通过本构方程和场方程推导出Love 波在电磁弹性介质中的波动方程。利用传递矩阵方法, 给出了一定边界条件下Love 波在该结构中的频散方程。通过对算例进行分析, 得出了Love 波在电磁弹性多层结构中传播的一些特性。      

非理想界面功能梯度压电/压磁双材料中的SH界面波

研究了非理想界面功能梯度压电/压磁双材料中SH界面波的传播特性,这里假定上、下半空间材料性能在垂直于界面的方向是按指数函数变化的。界面的机械条件由"弹簧"模型表征,即应力是连续的而位移是间断的;界面电磁学条件考虑电位移、电势、磁感、磁势连续和电学短路、磁学开路两种情况。推导了界面波显函形式的频散方程,通过数值计算表明了材料组合形式、界面非理想程度以及材料梯度变化对界面波相速度的影响。     

结构吸波复合材料透波层的研究

采用弓形法测试反射率,研究透波层的厚度、材质对结构吸波复合材料电磁性能的影响。结果显示,在4~18GHz范围内,厚度对其吸波性能具有显著影响,厚度分别为0.25、0.50和1.25mm的透波层,其结构吸波复合材料的最大吸收峰分别为-37.03,-33.45和-33.22dB;随厚度的增加,吸收峰的位置随向低频段显著漂移,-10dB的有效吸收带宽也显著变窄,分别为11.5,11和6.5GHz;与厚度相比,材质对结构吸波复合材料电磁性能影响较小。     

结构—介质单侧接触SH波散射动力相互作用的边界元分析

本文探讨了瞬态ＳＨ波作用下单侧接触的结构－介质动相互作用问题。给出了瞬态边界元列式，利用迭代技术计算了接触面上的响应。计算表明接触摩擦对动力呼应有很大的影响。     

SH wave propagation in a cylindrically layered piezoelectric structure with initial stress

Summary SH wave propagation in a cylindrically layered piezoelectric structure with initial stress is investigated analytically. By means of transformation, the governing equations of the coupled waves are reduced to Bessel and Laplace equations. The boundary conditions imply that the displacements, shear stresses, electric potential, and electric displacements are continuous across the interface between the layer and the substrate. The electrically open and short conditions at the cylindrical surface are applied to solve the problem. The phase velocity is numerically calculated for the electrically open and short cases, respectively, for different wavenumber and thickness of the layer. The effect of the initial stress on the phase velocity and the electromechanical coupling factor are discussed in detail for piezoelectric ceramics PZT-5H. We find that the initial stress has an important effect on the SH wave propagation in the cylindrically layered piezoelectric structures. The results also show that the ratio of the layer thickness to the wavelength has a remarkable effect on the SH wave phase velocity and electromechanical coupling factor.     

正交各向异性空心圆柱体的周向SH波

基于线性三维弹性理论,得到了正交各向异性管道中位移表示的周向波控制方程.波动方程中的轴向位移独立于其它两个方向.即波的传播可以分解为SH波和类Lamb波.通过贝塞尔函数求得了这个周向SH波频散方程.方程中决定周向SH波特性的弹性常数有两个,一个决定了波的频率,另一个决定了波速.最后分别讨论了两个弹性常数和波数变化对周向SH波位移模式的影响.     

Transference of SH waves through irregular interface between corrugated piezoelectric layer and prestressed viscoelastic substrate

An exact approach is used to investigate the horizontally polarized shear wave in an irregular piezoelectric layer with corrugated surface lying over prestressed viscoelastic substrate. Perturbation technique is used to solve the problem. Dispersion relations are obtained in closed form for electrically open and short cases. The main feature of the present work is its ability to investigate the effect of irregularity, corrugation, dielectric constant, piezoelectric constant, initial stress and viscoelastic parameter on the phase velocity of SH wave. Numerical example has been carried out to observe the profound effect of these affecting parameters on phase velocity of SH wave.     

Propagtion of SH wave in laminated elastic composite materials effect of frequency and of number of layers

This study is devoted to propagation of SH Waves (Shear Horizontal) in laminated elastic composite materials. Layers of material are perfectly bonded and reflection and transmission coefficients are given by transfer matrix method. Numerical results are pointed out through curves in which reflection and transmission coefficients are plotted versus incident angle. Composite materials with 3 and 10 layers are analysed at large and low wave-numbers compared with thickness of layers. We point out effects of frequency (or wave number) and of number of layers. Intending objective is to predict the quality of bonding by introducing elastic slip at interface between layers.     

基于机械品质因数的全波压电超声换能器设计

针对全波压电超声换能器常规设计方法存在的尺寸参数较多、计算较复杂等问题,研究了一种利用机械品质因数设计全波压电超声换能器的方法.基于压电超声理论推导了全波压电超声换能器的频率方程,利用电学理论推导了全波压电超声换能器各组成部分的等效电路,利用等效电路求取了在任意等效截面处的等效机械阻抗,进而推导出全波压电超声换能器各部...     

粘弹正交各向异性空心圆柱体周向SH波

基于Kelvin-Voight模型,推导了粘弹正交各向异性空心圆柱体周向SH波控制方程,得出了SH波特性受两个弹性常数与粘性系数的影响。通过第一类和第二类Bessel函数,求出频散方程。计算了四种不同径厚比下的相速度频散曲线和衰减曲线,分析了径厚比的变化对频散和衰减曲线的影响。为了与正交各向异性相比较,计算了粘弹各向同性空心圆柱体中周向SH波,并讨论了两个弹性常数和粘性系数对频散曲线和衰减曲线的影响。     

SH导波在钢板缺陷检测中的传播特性

水平剪切(Shear Horizontal,SH)导波在传播的过程中有对称模式和反对称模式,其相速度和群速度主要取决于试件的厚度和频率之积(频厚积)。利用COMSOL有限元分析软件,建立了钢板缺陷的3-D模型,仿真分析了SH0导波在钢板中的传播特性。仿真结果表明SH波在传播过程中很少发生波束方向的改变,无频散和模式转换,信噪比高。利用电磁超声方法激励SH波,对钢板中的裂纹和焊缝缺陷进行了实验,验证了仿真结果的正确性及可行性,为超声导波在板材缺陷检测中的应用提供基础。     

Bulk wave propagation in layered piezomagnetic/piezoelectric plates with initial stresses or interface imperfections

Bulk wave propagation in laminated piezomagnetic/piezoelectric plates with initial stresses and imperfect interface is investigated using the state space approach. Either electrically and magnetically open or shorted conditions on the top and bottom surfaces are considered. The phase velocity and frequency spectra of the wave are numerically calculated for various electric and magnetic conditions, and normalized modes are also analyzed. Although numerical results do indicate that the initial compressive stress can reduce the phase velocity of the wave propagating in a layered multiferroic structure, the effect is not as obvious as that reported in literature where the initial stresses were taken far beyond the strength of real materials. While the imperfect interface affect the frequency spectra much greater than initial stresses, because imperfection decreases the structural stiffness.