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21.
Based on the thermo-electro-elastic coupling theory, the mathematical model for a surface heated piezoelectric semiconductor (PS) plate is developed in the time domain. Applying the direct and inverse Laplace transformations to the established model, the mechanical and electrical responses are investigated. The comparison between the analytical solution and the finite element method (FEM) is conducted, which illustrates the validity of the derivation. The calculated results show that the maximum values of the mechanical and electrical fields appear at the heating surface. Importantly, the perturbation carriers tend to concentrate in the zone near the heating surface under the given boundary conditions. It can also be observed that the heating induced elastic wave leads to jumps for the electric potential and perturbation carrier density at the wavefront. When the thermal relaxation time is introduced, all the field quantities become smaller because of the thermal lagging effect. Meanwhile, it can be found that the thermal relaxation time can describe the smooth variation at the jump position. Besides, for a plate with P-N junction, the effect of the interface position on the electrical response is studied. The effects of the initial carrier density on the electrical properties are discussed in detail. The conclusions in this article can be the guidance for the design of PS devices serving in thermal environment. 相似文献
22.
This paper studies the problem of a functionally graded piezoelectric circular plate subjected to a uniform electric potential
difference between the upper and lower surfaces. By assuming the generalized displacements in appropriate forms, five differential
equations governing the generalized displacement functions are derived from the equilibrium equations. These displacement
functions are then obtained in an explicit form, which still involve four undetermined integral constants, through a step-by-step
integration which properly incorporates the boundary conditions at the upper and lower surfaces. The boundary conditions at
the cylindrical surface are then used to determine the integral constants. Hence, three-dimensional analytical solutions for
electrically loaded functionally graded piezoelectric circular plates with free or simply-supported edge are completely determined.
These solutions can account for an arbitrary material variation along the thickness, and thus can be readily degenerated into
those for a homogenous plate. A numerical example is finally given to show the validity of the analysis, and the effect of
material inhomogeneity on the elastic and electric fields is discussed.
Supported by the National Natural Science Foundation of China (Grant Nos. 10472102 and 10432030) and the Specialized Research
Fund for the Doctoral Program of Higher Education of China (Grant No. 20060335107) 相似文献
23.
讨论了低压微位移驱动电路及控制方法在光电轮廓仪上的运用。采用低压驱动电路驱动压电陶瓷相移器对参考光束进行相移,从而使仪器质量减轻、体积缩小、成本降低。在运用该电路时,为了解决压电陶瓷低电压区非线性误差大的问题,用PC计算机控制压电陶瓷上所加电压的电压值,由摄像头摄取图像并计算出干涉条纹的间隔,然后由PC计算机修改压电陶瓷上所加的电压值,直至干涉条纹相位差达到要求值。该方法的优点是:可消除压电陶瓷低压区的非线性误差,使得开环电路得到闭环的效果;可降低机械零部件的装配难度。 相似文献
24.
25.
A novel design method for high Q piezoelectric resonators was presented and proposed using the 3-D equations of linear piezoelectricity with quasi-electrostatic
approximation which include losses attributed to mechanical damping in solid and resistance in current conduction. There is
currently no finite element sofware for estimating the Q of a resonator without apriori assumptions of the resonator impedance or damping. There is a necessity for better and more
realistic modeling of resonators and filters due to miniaturization and the rapid advances in frequency ranges in telecommunication.
We presented new three-dimensional finite element models of quartz and barium titanate resonators with mechanical damping
and resistance in current conduction. Lee, Liu and Ballato’s 3-D equations of linear piezoelectricity with quasi-electrostatic
approximation which include losses attributed to mechanical damping in solid and resistance in current conduction were formulated
in a weak form and implemented in COMSOL. The resulting finite element model could predict the Q and other electrical parameters for any piezoelectric resonator without apriori assumptions of damping or resistance. Forced
and free vibration analyses were performed and the results for the Q and other electrical parameters were obtained. Comparisons of the Q and other electrical parameters obtained from the free vibration analysis with their corresponding values from the forced
vibration analysis were found to be in excellent agreement. Hence, the frequency spectra obtained from the free vibration
analysis could be used for designing high Q resonators. Results for quartz thickness shear AT-cut and SC-cut resonators and thickness stretch poled barium titanate resonators
were presented. An unexpected benefit of the model was the prediction of resonator Q with energy losses via the mounting supports. 相似文献
26.
In this letter, we investigate the influence of the stress on magnetoelectric (ME) effect in a magnetostrictive-PZT bilayer.
ME voltage coefficient α*E = δE / δH, where δE is the induced electric field for an applied alternating current (ac) magnetic field δH, is obtained by solving the stress-related piezoelectric constitutive equation and the conventional magnetostrictive equation
with appropriate boundary condition. Based on the free-energy density function of the PZT film in stress state, we get the
stress-related piezoelectric charge coefficient p
d*31 and dielectric permittivity pε*33. After taking the cobalt ferrite (CFO) as magnetostrictive phase, it is found that α*E increases with decreasing 2-d compressive stress for CFO-PZT, which not only is qualitatively consistent with previous experimental
measurements, but also provides a possible route to improve the ME effect.
相似文献
27.
28.
W.-Q. Chen 《Archive of Applied Mechanics (Ingenieur Archiv)》1999,69(7):455-464
Summary Utilizing the general solution of transversely isotropic piezoelectricity, the paper analyzes the problem of an inclined
rigid circular flat punch indenting a transversely isotropic piezoelectric half-space. The potential theory method is employed
and generalized to take into account the effect of the electric field in piezoelectric materials. Assuming that the punch
is maintained at a constant electric potential, exact expressions for the elastoelectric field are derived in terms of elementary
functions. It is noted that the solution corresponding to a flat circular punch centrally loaded by a concentrated force can
be obtained as a special case.
Received 15 December 1998; accepted for publication 9 March 1999 相似文献
29.
This paper is concerned with the optimum design and sensitivity analysis methods of piezoelectric intelligent trusses on the
structural stiffness and free-vibration frequency. On the basis of the finite element method and taking into account the mechanical-electric
coupling effect under electric load and mechanical load, the computational formula of sensitivities of structural displacement
and free-vibration frequency with respect to the size and shape design variables are proposed. A new kind of design variable
of the electric voltage and the calculating method of displacement sensitivity with respect to the electric voltage variable
is presented. The new method for structural deformation control by optimizing the voltages of piezoelectric active bars is
given. The numerical methods of optimum design and sensitivity analysis for piezoelectric truss structures are implemented
in JIFEX software. Numerical examples demonstrate the effectiveness of the methods and the program.
Project supported by the Special Funds for National Key Basic Research of China (No. G1999032805) and the Foundation for University
Key Teachers by the Ministry of Education of China. 相似文献
30.
Hairui Xia Jiyang Wang Lixia Li Zhigiang Zou 《Progress in Crystal Growth and Characterization of Materials》2000,40(1-4):253-261
A new series of non-ferroelectric crystals, the piezoelectric solid solution aluminium gallium orthophosphate Al1-xGaxPO4 (AGP, 0 < x < 1) system has been successfully developed by a hydrothermal method. The AGP crystal with X = 0.10 shows a phase transition temperature T−β = 587 ± 3 °C with a cell parameters A = b = 0.49386(3) and C = 1.09563(2) nm. Raman spectra including directional dispersion in AGP are similar to those from -AIPO4 and -quartz crystals, indicating all of them belong to an isomorphic family, the short-range interaction being dominant in AGP. Comparison with -AIPO4 crystals, there exists an apparent red shift of the mode frequency and a smaller TO/LO mode splitting of the E species in the AGP crystals. 相似文献