Zengtao Yang

Transmitting electric energy through a closed elastic wall by acoustic waves and piezoelectric transducers

Transmission of electric energy through a closed elastic wall by piezoelectric transducers and acoustic waves is studied based on the linear theory of piezoelectricity and elasticity. A theoretical analysis is performed. For the structure and motion considered, the 3D equations of linear piezoelectricity reduce to a 1D mathematical problem. An exact solution is obtained. Transmitted voltage, current, power, efficiency and stress distribution are obtained. Their dependence on various parameters is examined. The model and results of this paper are closer to real situations compared with those in a previous analysis.

A thickness mode acoustic wave sensor for measuring interface stiffness between two elastic materials

We studied thickness vibration of 2 elastic layers with an elastic interface mounted on a plate piezoelectric resonator. The effect of the interface elasticity on resonant frequencies was examined. The result obtained suggests an acoustic wave sensor for measuring the elastic property of an interface between 2 materials.

Energy trapping in power transmission through a circular cylindrical elastic shell by finite piezoelectric transducers

We study the transmission of electric energy through a circular cylindrical elastic shell by acoustic wave propagation and piezoelectric transducers. Our mechanics model consists of a circular cylindrical elastic shell with finite piezoelectric patches on both sides of the shell. A theoretical analysis using the equations of elasticity and piezoelectricity is performed. A trigonometric series solution is obtained. Output voltage and transmitted power are calculated. Confinement and localization of the vibration energy (energy trapping) is studied which can only be understood from analyzing finite transducers. It is shown that when thickness-twist mode is used the structure shows energy trapping with which the vibration can be confined to the transducer region. It is also shown that energy trapping is sensitive to the geometric and physical parameters of the structure.

Effect of mass layer stiffness on propagation of thickness-twist waves in rotated Y-cut quartz crystal plates

We analyze the effect of mass layer stiffness on thickness-twist waves propagating in a rotated Y-cut quartz crystal plate with thin mass layers on its surfaces. An equation that determines the dispersion relation of the waves is given and is solved numerically. Quantitative results of the effect of the mass layer stiffness on wave frequencies are presented. These results are important to the understanding and design of resonators and mass sensors.

Optimal electrode shape and size of a few singly rotated quartz and langasite resonators

Based on Mindlins early work, we calculate and plot optimal electrode shape and size of Y-cut quartz, At-cut quartz, and Y-cut langasite plate thickness-shear resonators. The electrodes obtained are optimal in that they satisfy Bechmanns number in every direction. The results are useful in the design optimization of these resonators.

Energy trapping in power transmission through an elastic plate by finite piezoelectric transducers

We study transmission of electric energy through an elastic plate by acoustic wave propagation and piezoelectric transducers. Our mechanics model consists of an elastic plate with finite piezoelectric patches on both sides of the plate. A theoretical analysis using the equations of elasticity and piezoelectricity is performed. Energy trapping that describes the confinement and localization of the vibration energy is examined.

Thickness-shear vibration of rotated Y -cut quartz plates with unattached electrodes and asymmetric air gaps

Thickness-shear vibration modes of rotated Y-cut quartz plates with unattached electrodes and asymmetric air gaps are analyzed. An exact solution is obtained from the equations of piezoelectricity. Numerical results calculated from the solution show that the resonant frequencies are sensitive to the dimensions of the air gaps. This offers new design parameters for better resonator performance.

Nonlinear coupling between thickness- shear and thickness-stretch modes in a rotated y-cut quartz resonator

We point out an implication of the Poynting effect in nonlinear elasticity. It is shown that, due to the Poynting effect, thickness-stretch vibration can be induced in a plate thickness-shear mode resonator of rotated Y-cut quartz when the thickness-shear deformation is no longer infinitesimal. This nonlinear coupling is particularly strong when the frequency of the thickness-stretch mode is twice the frequency of the thickness-shear mode. The induced thickness-stretch vibration affects the operating thickness-shear mode through Mathieus equation.We point out an implication of the Poynting effect in nonlinear elasticity. It is shown that, due to the Poynting effect, thickness-stretch vibration can be induced in a plate thickness-shear mode resonator of rotated Y-cut quartz when the thickness-shear deformation is no longer infinitesimal. This nonlinear coupling is particularly strong when the frequency of the thickness-stretch mode is twice the frequency of the thickness-shear mode. The induced thickness-stretch vibration affects the operating thickness-shear mode through Mathieus equation.

Nonlinear behavior of electric power transmission through an elastic wall by acoustic waves and piezoelectric transducers

Weakly nonlinear behavior of electric power transmission through an elastic wall by piezoelectric transducers and acoustic waves near resonance is studied based on the cubic theory of nonlinear electroelasticity. An approximate analytical solution is obtained. Output voltage is calculated and plotted. Basic nonlinear behaviors of the power transmission structure are examined. It is found that near nonlinear resonance the electrical input-output relation loses its linearity, becomes multi-valued, and experiences jumps due to large mechanical deformations. The behavior below and above resonance is qualitatively different and is qualitatively material dependent.

Modeling of power transmission through an elastic wall by piezoelectric transducers and acoustic waves

We present our recent modeling results on power transmission through an elastic wall by piezoelectric transducers and acoustic waves. This includes the case of finite piezoelectric transducers on plates, power transmission through circular cylindrical shells, and mechanical nonlinearity due to large deformations near resonance.