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1.
扭转压电复合材料及其应用   总被引:4,自引:1,他引:3       下载免费PDF全文
本文描述了轴向-切向连通的圆柱2-2型压电复合材料。用PZT/环氧树脂制作的普通2-2型压电复合材料可拼接成一种具有扭转振动的压电复合材料。这种压电复合材料和为圆柱2-2型压电复合材料的近似。本文还给出两组这种拼接型压电材料晶片的参数,用这种压电材料制作了产生扭转振动的换能器,测试了换能器的波形,频谱特性和偏振特性,指出了使用适当的高通滤波器可以抑制横波中的径向模,分析了接收波列中纵波抑制较强的原  相似文献   

2.
1-3型压电复合材料   总被引:9,自引:2,他引:7       下载免费PDF全文
1-3型压电复合材料是目前研究和应用得比较广泛的一种压电材料.本文简述了这种压电复合材料的理论模型、制作方法和实验结果;指出除了圆形PZT压电材料所具有的径向模和厚度模以外,1-3型压电复合材料还具有横向结构模.本文介绍了这种压电复合材料的特点,如低声阻抗、低介电常数、高静水压压电常数以及PZT相分布的可控制性等.这些特点有利于改善压电复合材料换能器的时间响应和空间响应.  相似文献   

3.
本文通过控制压电相在压电复合材料中的分布形式,把四块完全相同的等腰直角王角形2-2型压电复合材料拼接起来,四个直角顶点位于晶片的中心,相邻块压电相的极化方向相对.这种新型材料可产生面切变振动,其换能器可辐射面切变波.波列中的纵波具有伴随性且其首波位相与面切变波首波位相相反  相似文献   

4.
面切变压电复合材料及其换能器   总被引:1,自引:1,他引:0       下载免费PDF全文
本文通过控制压电相在压复合材料中的分布工,把四块完全相同的等腰直角三角形2-2型压电复合拼材料拼接起来,四个直角顶点位于晶片的中心,  相似文献   

5.
本文利用1-3压电复合材料作为换能元件,通过特殊工艺制备成一面是平面,一面是球面的非均匀厚度压电振子,这种压电晶片加上激励电压后,不同厚度处以不同的共振频率振动,从而使压电晶片的振动频带加宽,本文介绍了这种压电晶片的机电特性,以及用这种压电晶片制成的宽带聚焦超声换能器的脉冲回波特性,此外,文中还对这种换能器与均匀厚度压电晶片换能器的脉冲回波特性进行了比较。  相似文献   

6.
在固体测量中,横波换能器所产生的波列中常伴随有纵波,认识纵波产生的原因可以解释横波测试中出现的现象,以及抑制纵波提供有效的方法,本文利用实验研究的方法,用一对纵波偶极子换能器的对比实验,分析了2-2型压电复合材料厚度切变换能器产生纵波的机理,发现这是一种伴随着晶片厚度切变振动而产生的“偶极子”纵波,并由此解释了这种纵波的伴随性,频率特性及其首波与横波首波位相相反等问题。  相似文献   

7.
压电复合材料宽带横波换能器的实验研究   总被引:13,自引:4,他引:9       下载免费PDF全文
本文用实验方法研究了2-2压电复合材料的厚度切变特性,定性地给出了2-2压电复合材料的性能与PZT相体积百分比,以及与共振频率牟关系。并用这种材料作为换能元件,制作出高灵敏度窄脉冲横波换能器。  相似文献   

8.
本文介绍了一种2-2型压电复合材料,使其中的极化方向和所加电场方向相同,并垂直于该方向而辐射声波。  相似文献   

9.
万奕  李智 《应用声学》1997,16(4):27-31
本文介绍了一种具有2-2结构特征的三相压电复合材料的结构及其制备方法,并与一种二相压电复合材料的类似结构对对比,进行了横向耦合,频率特性,声阻抗和介电性能等方面的测试和讨论,同时介绍了这种三相复合成功地应用于线阵换能器的结果。  相似文献   

10.
刘殿锋  李明轩 《应用声学》1998,17(1):11-14,42
通过调整1-3型压电复合材料换能器中压电相的分布,可以控制换能器辐射面上振动幅度和相位的分布,从而获得具有特殊性能的声场。  相似文献   

11.
Sound radiation from shear deformable stiffened laminated plates   总被引:1,自引:0,他引:1  
Sound radiation from shear deformable stiffened laminated plates is studied theoretically. The equations of motion for the composite laminated plate are derived on the basis of the first-order shear deformation plate theory. Two sets of parallel stiffeners interact with the laminated plate only through the normal line forces. By using the Fourier wavenumber transform and the stationary phase method, the far-field sound pressure is described analytically. Sound pressure given by the first-order shear deformation plate theory and the classical thin plate theory is compared, and the differences of sound pressure are shown in the high frequency range for an isotropic plate. Sound pressure and the transverse displacement spectra are presented to illustrate the effects of force location, stiffeners and angle-ply layers. Sound radiation from symmetric and antisymmetric composite plates with multiple loadings is also investigated.  相似文献   

12.
The governing equation for the finite element analysis of the panel flutter of composite plates including structural damping is derived from Hamilton's principle. The first order shear deformable plate theory has been applied to structural modelling so as to obtain the finite element eigenvalue equation. The unsteady aerodynamic load in a supersonic flow is computed by using the linear piston theory. The critical dynamic pressures for composite plates have been calculated to investigate the effects of structural damping on flutter boundaries. The effects are dependent on fiber orientation because flutter mode can be weak or strong in the fiber orientation of composite plates. Structural damping plays an important role in flutter stability with low aerodynamic damping but would not affect the flutter boundary with high aerodynamic damping.  相似文献   

13.
In this paper, the dynamic instability of a shear deformable composite plate subjected to periodic non-uniform in-plane loading is studied for four sets of boundary conditions. The static component and the dynamic component of the applied periodic in-plane loading are assumed to vary according to either parabolic or linear distributions. Initially, the plate membrane problem is solved using the Ritz method to evaluate the plate in-plane stress distributions within the prebuckling range due to the applied non-uniform in-plane edge loading. Subsequently using the evaluated stress distribution within the plate, the equations governing the plate instability boundaries are formulated via Hamilton's variational principle. Employing Galerkin's method, these partial differential equations are reduced into a set of ordinary differential equations (Mathieu type of equations) describing the plate dynamic instability behaviour. Following Bolotin's method, the instability regions are determined from the boundaries of instability, which represents the periodic solution of the differential equations with period T and 2T to the Mathieu equations. The instability regions are determined for uniform, linear and parabolic dynamic in-plane loads using first-order and second-order approximations. Numerical results are also presented to bring out the effects of span to thickness ratio, shear deformation, aspect ratio, boundary conditions and static load factor on the instability regions.  相似文献   

14.
为了获得大负载平行砂轮复合变幅器的设计方法,将复合变幅器简化为复合变幅杆与多阶环盘组成。利用Mindlin中厚板理论,求解了各振动环盘的位移、转角、弯矩和剪力解析表达式,并通过复合变幅杆各振动单元间的力、位移的边界条件和连续条件,以及复合变幅杆和环盘两者结构间力与位移的耦合条件,建立了复合变幅器的数学模型和频率方程。针对频率方程进行编程求解 ,设计了平行砂轮复合变幅器。通过有限元仿真分析、实物阻抗特性试验、谐振试验验证。试验结果表明:平行砂轮复合变幅器的试际谐振频率、节圆位置与理论设计的误差小于5%,验证了其理论设计方法的正确性。为研制大负载平行砂轮复合变幅器提供了一种有效的设计方法。  相似文献   

15.
The nonlinear free vibration of carbon nanotubes/fiber/polymer composite (CNTFPC) multi-scale plates with surface-bonded piezoelectric actuators is studied in this paper. The governing equations of the piezoelectric nanotubes/fiber/polymer multiscale laminated composite plates are derived based on first-order shear deformation plate theory (FSDT) and von Kármán geometrical nonlinearity. Halpin–Tsai equations and fiber micromechanics are used in hierarchy to predict the bulk material properties of the multiscale composite. The carbon nanotubes are assumed to be uniformly distributed and randomly oriented through the epoxy resin matrix. A perturbation scheme of multiple time scales is employed to determine the nonlinear vibration response and the nonlinear natural frequencies of the plates with immovable simply supported boundary conditions. The effects of the applied constant voltage, plate geometry, volume fraction of fibers and weight percentage of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) on the linear and nonlinear natural frequencies of the piezoelectric nanotubes/fiber/polymer multiscale composite plate are investigated through a detailed parametric study.  相似文献   

16.
提出了一种计算上下面板非对称的三明治夹芯板隔声性能的方法。通过对非对称夹芯梁表观抗弯曲刚度的计算,得到对应夹芯板随频率变化的表观抗弯刚度,代入4阶的控制方程,应用模态展开法可以方便地计算简支非对称夹芯板的隔声量。对4种定制的3层非对称碳纤维夹芯板进行了理论计算和实验测试对比,在频率范围100~3150 Hz内,计权隔声量误差在3 dB以内。着重分析了面板对称性、芯层剪切模量对隔声性能的影响,发现在夹芯板面密度一定时,芯层剪切模量对夹芯板的隔声性能影响最为显著。当芯层剪切模量较小时,上下面板非对称分布导致吻合频率显著降低,对夹芯板的整体隔声亦不利。   相似文献   

17.
《Composite Interfaces》2013,20(4):283-300
This paper deals with the influence of adhesive properties on the interlaminar stress in externally FRP plated steel beams. The analysis provides efficient calculations for both shear and normal interfacial stresses in steel beams strengthened with composite plates, and accounts for various effects of Poisson's ratio and Young's modulus of adhesive. Such interfacial stresses play a fundamental role in the mechanics of plated beams, because they can produce a sudden and premature failure. The analysis is based on equilibrium and deformations compatibility approach developed by Tounsi [1]. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the steel beam and bonded plate. The paper concludes with a summary and recommendations for the design of the strengthened beam.  相似文献   

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