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压电纳米材料具有机电耦合性强、功耗低和反应灵敏等独特性能,且能满足工程对压电器件微型化的要求,从而在传感、微纳米机电系统和柔性电子器件等领域展现出了广阔的应用前景.高比表面积引起的表面效应是压电纳米材料最重要的结构特征之一,其对材料的整体力学性质起着决定性的作用.表面效应会导致应力和电位移在压电表面的两侧出现间跃,故传统的力电场连续性条件将不再适用.考虑表面为不计厚度却拥有独立材料参数的薄层,采用表面压电模型计及表面弹性、表面压电性、表面介电性和表面密度的影响,本文研究了压电纳米板中SH型导波的传播特性,给出了板边界处的非典型力电平衡条件,得到了频散方程的解析表达,并结合数值算例详细讨论了表面材料参数和结构尺寸对对称和反对称频散模态的影响.结果表明:SH型导波在压电纳米板中的传播具有明显的尺寸相关性,即当板厚很小时,表面效应会显著改变其频散行为,而随着板厚的增大,表面效应的影响会不断减弱直至可忽略不计. 相似文献
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压电纳米材料具有机电耦合性强、功耗低和反应灵敏等独特性能,且能满足工程对压电器件微型化的要求,从而在传感、微纳米机电系统和柔性电子器件等领域展现出了广阔的应用前景. 高比表面积引起的表面效应是压电纳米材料最重要的结构特征之一,其对材料的整体力学性质起着决定性的作用.表面效应会导致应力和电位移在压电表面的两侧出现间跃,故传统的力电场连续性条件将不再适用.考虑表面为不计厚度却拥有独立材料参数的薄层,采用表面压电模型计及表面弹性、表面压电性、表面介电性和表面密度的影响,本文研究了压电纳米板中SH型导波的传播特性,给出了板边界处的非典型力电平衡条件,得到了频散方程的解析表达,并结合数值算例详细讨论了表面材料参数和结构尺寸对对称和反对称频散模态的影响.结果表明:SH型导波在压电纳米板中的传播具有明显的尺寸相关性,即当板厚很小时,表面效应会显著改变其频散行为,而随着板厚的增大,表面效应的影响会不断减弱直至可忽略不计. 相似文献
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纳米科技的快速发展使压电纳米结构在纳米机电系统中得到广泛应用,形成了诸如纳米压电电子学等新的研究方向.与传统的宏观压电材料相比,在纳米尺度下压电材料往往呈现出不同的力学特性,而造成这种差异的原因之一便是表面效应.本文基于Stroh公式、Barnett-Lothe积分矩阵及表面阻抗矩阵,研究计入表面效应的任意各向异性压电半空间中的表面波传播问题,导出了频散方程.针对横观各向同性压电材料,假设矢状平面平行于材料各向同性面,发现Rayleigh表面波和B-G波解耦,并得到各自的显式频散方程.结果表明,Rayleigh表面波的波速小于偏振方向垂直于表面的体波,而B-G波的波速小于偏振方向垂直于矢状平面的体波.以PZT-5H材料为例,用数值方法考察表面残余应力和电学边界条件对表面波频散特性的影响发现:表面残余应力只对第一阶Rayleigh波有明显的影响;电学开路情形的B-G波比电学闭路情形的B-G波传播快.本文工作可为纳米表面声波器件的设计或压电纳米结构的无损检测提供理论依据. 相似文献
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本文利用Chen和Shioya给出的在横观各向同性压电无限体内币形裂纹上下表面作用对称法向点力和点电荷情形下的解,结合压电材料之功的互等定,用初等函数的形式给出了在压电无限体中任意一点作用任意点力和点电荷情形下币形裂纹的张开位移,并对PZT-4压电陶瓷和非压电材料作了计算分析。 相似文献
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研究了双压电材料中广义压电位错与分布于界面的刚性共线线夹杂相互作用问题.基于线性压电理论Stroh框架,相应的混合边值问题,可化为常见的Hilbert问题.求解Hilben问题,得到存在界面刚性线夹杂与位错时,压电体内所有场变量的显式表达.给出了由于界面和刚性线夹杂的存在,作用于广义压电位错上的广义Peach-Koehler镜像力.对均匀压电材料这一特殊情况,给出了数值算例,讨论了位错对刚性线夹杂端部场强度因子的干涉和它们之间的相互作用.结果可作为求解界面刚性线夹杂与微裂纹交互作用问题的Green函数,也可作为边界元方法的核函数. 相似文献
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有限厚压电层表面金属电极脱层的屈曲研究 总被引:1,自引:0,他引:1
基于弹性有限变形理论和压电弹性体偏场理论,对上、下表面有金属电极的压电材料板内存在穿透脱层的屈曲问题进行了分析.采用平面应变模型,远处作用有均匀压应变载荷.用Fourier积分变换,界面连续条件和上、下电极表面的边界条件将问题归为第二类Cauchy型奇异积分方程组.利用Gauss-Chebyshev积分公式将该方程组变为一齐次线性代数方程组,以确定脱层屈曲载荷.算例给出了中间层为PZT-4,上、下电极为Pt的结构在不同脱层长厚比时的临界应变及相应屈曲形状.同时分析了压电层的机电耦合效应对临界应变的影响. 相似文献
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The paper is concerned with the problem of stability of a power transmitting thin-walled shaft made of the active laminate PFC (piezoelectric fiber composite). The shaft rotates with a given operational angular velocity, and is loaded by a static torque. Such a system is known to exhibit divergence or oscillating type of instability. On the one hand presence of internal friction in the material of the shaft leads to loss of stability at a certain critical rotation speed. The static torque can be responsible for spatial deformation of the shaft axis on the other. A method preventing the system from such behavior is discussed in the paper. The method is based on application of a composite material, which contains active piezoelectric fibers. The fibers produce bending moments, and this way affect the dynamics of the entire system. Two control strategies are investigated. Results of numerical simulations are presented graphically. 相似文献
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The plane motion of a rigid body with a discrete mass distribution and a material point under mutual attraction is considered. The stationary configurations of this mechanical system are studied in the case when the mass of the material point can be ignored and the body rotates about its mass center at a nonzero angular velocity and in the general case of mutual interaction between the body and the material point. It is shown that in this mechanical system there always exist at least two different positions of relative equilibrium. 相似文献
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The propagation of Lamb waves in a homogeneous, transversely isotropic (6 mm class), piezothermoelastic plate rotating with uniform angular velocity about normal to its boundary has been investigated. The generalized (non-classical) theories of thermoelasticity in contrast to Sharma and Pal [Sharma, J.N., Pal, M., 2004. Lamb wave propagation in transversely isotropic piezothermoelastic plate. J. Sound Vib. 270, 587–610] have been used to investigate the problem. The surfaces of the plate are subjected to stress free, thermally insulated/isothermal and electrically shorted boundary conditions. Secular equations for wave propagation modes in the plate are derived from a coupled system of governing partial differential equations of linear piezothermoelasticity. After obtaining the complex characteristic roots with the help of Descartes' algorithm, the transcendental secular equations have been solved by functional iteration numerical technique to compute phase velocity and attenuation coefficient. Finally, in order to illustrate the analytical development, numerical solution of secular equations is carried out for PZT-5A piezo-thermoelastic material. The corresponding simulated results of various physical quantities such as phase velocity, attenuation coefficients, specific loss factor of energy dissipation, thermo-mechanical coupling factor and relative frequency shifts have been presented graphically for both rotating and non-rotating plates for comparison purpose. There is a scope for extension of the present work to other classes of piezo/pyroelectric crystals. The study will be useful in design and construction of gyroscope, rotation sensors, temperature sensors and other pyro/piezoelectric surface acoustic wave (SAW) devices. 相似文献
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PROPAGATION OF SURFACE ACOUSTIC WAVES IN PRESTRESSED ANISOTROPIC LAYERED PIEZOELECTRIC STRUCTURES 总被引:1,自引:0,他引:1
Liu Hua Kuang Zhenbang Cai Zhengming 《Acta Mechanica Solida Sinica》2003,16(1):16-23
The propagation of surface acoustic waves in layered piezoelectric structures withinitial stresses is investigated.The phase velocity equations are obtained for electrically free andshorted cases,respectively.Effects of the initial stresses on the phase velocity and the electrome-chanical coupling coefficient for the fundamental mode of the layered piezoelectric structures arediscussed.Numerical results for the c-axis oriented fihn of LiNbO_3 on a sapphire substrate aregiven.It is found that the fractional change in phase velocity is a linear function with the ini-tial stresses,and the electromechanical coupling factor increases with an increase of the absolutevalues of the compressive initial stresses.The results are useful for the design of surface acousticwave devices. 相似文献
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分析了弹性上下半空间和PMN‐PT单晶层组成的夹层结构中SH波的传播性质,PMN‐PT单晶沿[011]c方向极化,宏观上呈mm2对称,且晶体沿角度θ方向切割。基于正交各向异性压电材料和各向同性弹性材料的基本方程,得到了夹层结构中SH波传播时行列式形式的频散方程。通过对数值算例进行分析可以看出,PMN‐PT单晶的切割角度和弹性材料属性对结构中的相速度有很大影响,因此波的某些传播性能可以通过材料的设计以及晶体切割的方向来实现,这些结论为声表面波器件的开发和应用提供了理论依据。 相似文献
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J. S. Yang Z. G. Chen Y. T. Hu S. N. Jiang S. H. Guo 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(10):689-696
We study thickness-twist vibrations and waves in an unbounded, multi-sectioned piezoelectric plate of crystals with 6 mm symmetry
or polarized ceramics. An exact solution from the three-dimensional equations of piezoelectricity is obtained. Basic vibration
and wave propagation characteristics are calculated based on the solution. The results are useful in the understanding and
design of plate resonators, filters and acoustic wave sensors of ZnO, AlN and polarized ceramics. 相似文献
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X. Y. Li Z. K. Wang S. H. Huang 《International Journal of Solids and Structures》2004,41(26):310-7328
To investigate the features of Love waves in a layered functionally graded piezoelectric structure, the mathematical model is established on the basis of the elastic wave theory, and the WKB method is applied to solve the coupled electromechanical field differential equation. The solutions of the mechanical displacement and electrical potential function are obtained for the piezoelectric layer and elastic substrate. The dispersion relations of Love waves are deduced for electric open and short cases on the free surface respectively. The actual piezoelectric layer–elastic substrate systems are taken into account, and some corresponding numerical examples are proposed comparatively. Thus, the effects of the gradient variation about material constants on the phase velocity, the group velocity, the coupled electromechanical factor and the cutoff frequency are discussed in detail. So the propagation behaviors of Love waves in inhomogeneous medium is revealed, and the dispersion and the anti-dispersion are analyzed. The conclusions are significant both theoretically and practically for the surface acoustic wave devices. 相似文献
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The influence of a viscous liquid on acoustic waves propagating in elastic or piezoelectric materials is of particular significance for development of liquid sensors. Bleustein–Gulyaev wave is a shear-type surface acoustic wave and has the advantage of not radiating energy into the adjacent liquid. These features make the B–G wave sensitive to changes in both mechanical and electrical properties of the surrounding environment. The Bleustein–Gulyaev wave has been reported to be a good candidate for liquid sensing application. In this paper, we investigate the potential application of B–G wave in 6 mm crystals for liquid sensing. The explicit dispersion relations for both open circuit and metalized surface boundary conditions are given. A numerical example of PZT-5H piezoelectric ceramic in contact with viscous liquid is calculated and discussed. Numerical results of attenuation and phase velocity versus viscosity, density of the liquid and wave frequency are presented. The paper is intended to provide essential data for liquid senor design and development. 相似文献