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51.
Based on Timoshenko beam model, a theoretical model of radially polarized piezoelectric ceramic tubes is investigated. In the model, the piezoelectric effects are considered, and the shear correction factor is introduced which reveals effects of the size of the cross-section and Poisson’s ratio. Based on the model, the particular attentions are devoted to effects of the boundary conditions at two ends on flexural resonance frequencies of the piezoelectric ceramic tubes. Changing the sizes of the tubes and the mass loads at both free ends, the variations of the flexural resonance frequencies of free–free piezoelectric ceramic tubes are calculated theoretically. Besides, the flexural resonance frequencies of the piezoelectric ceramic tube cantilevers with mass loads at one free end are also investigated theoretically. To verify accuracy of the theoretical mode, the flexural resonance frequencies for different lengths of the piezoelectric ceramic tubes and different loaded masses are measured experimentally. The theoretical results agree well with the experimental measurement, which demonstrates that the model is accurate for analyzing the flexural resonance frequencies of the piezoelectric ceramic tubes with mass loads. 相似文献
52.
为了提高镀层的表面质量,提出了一种超声辅助电镀的方法。超声的空化与搅拌作用可以影响电镀的电沉积过程。设计了合理的换能器结构,并搭建了超声辅助电镀装置。通过对模型进行压电声学场与电镀场耦合仿真分析,结果表明:在硫酸铜电解液,镀铜时间60s,电压300V条件下,进行超声辅助电镀,镀层厚度分布均匀,镀层中部电流密度分布均匀,边缘最大电流密度是未加超声的2倍左右 。基于仿真结果,进行相同的实验测试,结果表明:超声辅助电镀可以提高镀层的均匀性,减少铜颗粒表面的杂质,提高表面的光洁度。阴极样品距离换能器头部位置在60mm左右,镀层质量良好。 相似文献
53.
54.
This work designed and prepared a novel heterojunction composite NiO/BaTiO3 through a method of photodeposition and used it in piezocatalytic dye removal for the first time. Results of the piezocatalytic test indicated that the NiO/BaTiO3 composite presented superior efficiency and stability in the RhB degradation under the vibration of ultrasonic waves. The best NiO/BaTiO3 sample synthesized under light irradiation for 2 h displayed an RhB degradation rate of 2.41 h−1, which was 6.3 times faster than that of pure BaTiO3. By optimizing the piezocatalytic reaction conditions, the degradation rate constant of NiO/BaTiO3 can further reach 4.14 h−1 A variety of systematic characterizations were executed to determine the reason for the excellent piezocatalytic performance of NiO/BaTiO3. The band potentials of NiO and BaTiO3 are found to coincide, and at their contact interface, they may create a type-II p-n heterojunction structure. Driven by the potential difference and the built-in electric field, piezoelectrically enriched charge carriers can migrate between NiO and BaTiO3, resulting in improved efficiency in charge separation and an increase in the piezoelectric catalytic performance. This study may provide a potential composite catalyst and a promising idea for the design of highly efficient catalysts in the field of piezoelectric catalysis. 相似文献
55.
56.
Both the mechanical and the electrical damages are introduced to study fracture mechanics of piezoelectric ceramics in this paper. Two kinds of piezoelectric fracture criteria are proposed by using the damage theory combined with the well-known piezoelectric fracture experiments of Park and Sun [Fracture criteria of piezoelectric ceramics, J. Am. Ceram. Soc. 78 (1995) 1475-1480]. One is based on a critical state of the mechanical damage and the other on a critical value of a proper linear combination of both the mechanical and the electrical damage variables. It is found that the fracture load predicted, which takes the mechanical damage into account only (mode 1), has greater deviation than predicted result by considering a proper linear combination of the mechanical and the electrical damages (mode 2). And the fracture criterion corresponding to mode 2 presented is shown to be superior to mode 1. It is also demonstrated that the mechanical damage has greater effect on fracture than the electrical damage. 相似文献
57.
Qing-Hua Qin Jian-Shan Wang Yi-Lan Kang 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,75(8-9):527-540
A theoretical model is presented to study the elastic deformation process and frictional sliding behavior in single piezoelectric
fibre push-out tests. Based on the theoretical model and some necessary simplifications, stress and electric fields are obtained
for push-out tests of a circular piezoelectric fibre embedded in an elastic matrix. Numerical results of a piezoelectric fibre/expoxy
matrix system are presented to verify the proposed formulation. The study shows that there is a significant effect of the
piezoelectric parameter and embedded fibre length on stress transfer, electric field distribution and load-displacement curve
of the frictional sliding process. This study also indicates that the piezoelectric effect has a distinct influence on the
mechanical behavior and properties of the interface in a fibre/matrix system. 相似文献
58.
T.-H. Chen C.-H. Chue H.-T. Lee 《Archive of Applied Mechanics (Ingenieur Archiv)》2004,74(3-4):248-261
Summary In this paper, the stress singularities for a cylindrically polarized piezoelectric wedge are investigated. The characteristic
equations are derived analytically by using the extended Lekhnitskii formulation. The piezoelectric material (PZT-4) is polarized
in the radial, circular or axial direction, respectively. Similar to the rectilinearly polarized piezoelectric problem, the
inplane and antiplane stress fields are uncoupled. The results show the variations of the singularity orders with the changes
of the wedge angle, material constants, polarized direction, and the boundary conditions. 相似文献
59.
Discussion of Antiplane Singularities of Piezoelectric–Dielectric and Piezoelectric–Conductor Wedges
T. J. C. Liu C. D. Chen C. H. Chue 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,76(3-4):245-248
This technical note deals with two special topics from our previous paper (Chue and Chen in Arch Appl Mech 72 673–685, 2003) in Archive of Applied Mechanics: the effects of electrical conditions imposed on the edges and bonded interfaces of piezoelectric–dielectric and piezoelectric–conductor wedges on antiplane problems. After employing relatively realistic electrical conditions, we found that stress and electric displacement singularities are altered when boundary conditions and/or continuity conditions are changed, and we compared the results with those of previous studies. 相似文献
60.
X.-F. Li 《Archive of Applied Mechanics (Ingenieur Archiv)》2003,72(10):745-758
Summary The dynamic problem of an impermeable crack of constant length 2a propagating along a piezoelectric ceramic strip is considered under the action of uniform anti-plane shear stress and uniform
electric field. The integral transform technique is employed to reduce the mixed-boundary-value problem to a singular integral
equation. For the case of a crack moving in the mid-plane, explicit analytic expressions for the electroelastic field and
the field intensity factors are obtained, while for an eccentric crack moving along a piezoelectric strip, numerical results
are determined via the Lobatto–Chebyshev collocation method for solving a resulting singular integral equation. The results
reveal that the electric-displacement intensity factor is independent of the crack velocity, while other field intensity factors
depend on the crack velocity when referred to the moving coordinate system. If the crack velocity vanishes, the present results
reduce to those for a stationary crack in a piezoelectric strip. In contrast to the results for a stationary crack, applied
stress gives rise to a singular electric field and applied electric field results in a singular stress for a moving crack
in a piezoelectric strip.
Received 14 August 2001; accepted for publication 24 September 2002
The author is indebted to the AAM Reviewers for their helpful suggestions for improving this paper. The work was supported
by the National Natural Science Foundation of China under Grant 70272043. 相似文献