Piezoelectric Equivalent Circuit Research Articles

Experimental and numerical study of underwater piezoelectric generator based on Vortex-induced Vibration

Efficient energy use to be transformed into electricity for small power devices has drawn increasing attention. A piezoelectric energy harvester is proposed to convert flow energy underwater to electrical energy. The harvester consists of the connecting device, springs, base, bluff body, piezoelectric cantilever beam and displacement sensor. The output voltage is derived from the flow-solid-electric coupling equations, including a nonlinear van der Pol equation, a linear equation of structural vibration and a piezoelectric equivalent circuit. Vibration response and output performance are obtained based on the finite central difference method. The theoretical results show that the vibration frequency, amplitude and average power increase with the limited water velocity. Furthermore, it is demonstrated that a proper selection of structure mass and load resistance can improve average harvested power for the available water velocity. Finally, the experimental prototype is fabricated to test piezoelectric generator performance at different water speeds, which shows good agreement with the theoretical results. This work provides a significant guide for the underwater use of piezoelectric energy harvesters.

Optimization Design of Ultrasonic Transducer With Multimatching Layer.

An optimization design strategy is developed for ultrasonic transducer (UT) with multimatching layer to improve its performance. The piezoelectric equivalent circuit model is used to determine the optimization interval of matching layer, and the PiezoCAD software is used to simulate the performance of UT with multimatching layer. The neural network (NN) models are trained by the simulation data to characterize the relationship between the thickness of matching layer and performance of UT. Then, the multiobjective optimality criteria for UT is established based on its performance parameters, including center frequency (CF), -6 dB bandwidth (BW) and pulsewidth (PW). The thickness of matching layer is optimized by particle swarm optimization (PSO) algorithm. According to the designed performance, the optimized copper thickness and parylene thickness are about 17.76 and [Formula: see text], respectively. The simulation results of UT with the optimized multimatching layer well agree with the designed targets. Also, CF, -6 dB BW, and PW of the fabricated UT with the optimized multimatching layer are 5.672 MHz, 50.08%, and [Formula: see text], respectively, which nearly achieve the designed performance. In addition, the performance of UT with the optimized multimatching layer is much better than that of UT without matching layer. Moreover, compared with UT with single or double matching layers determined by the quarter wavelength theory, the UT with the optimized multimatching layer has better comprehensive performance. Finally, the fabricated UT with the optimized multimatching layer is used to measure the thickness of testing block, and the relative errors are all less than 1.0%, which implies that the optimized UT has excellent performance.

Analysis of ultrasonic vibro-impact systems with equivalent circuits and the harmonic balance method

Vibro-impacts are essential for many ultrasonic applications like ultrasonic welding or ultrasonic motors. These systems are described with a piezoelectric equivalent circuit, that is extended by an impact and a static deflection. As long as the movement of the system is mainly sinusoidal, the method of harmonic balance gives a good approximation of the vibration behaviour. It is known, that the mounting situation has a great influence on the characteristic of a vibro impact system. Therefore the analytical solution of the equivalent circuit is given and discussed for a constant pressing force, a constant gap and an arbitrary foundation stiffness. It turns out that, the dependency of static and harmonic deflection gives a good explanation and deeper understanding of vibro-impact systems. Finally the model is compared to measurements with a constant pressing force.

Piezoelectric Properties of Aluminum Nitride for Thin Film Bulk Acoustic Wave Resonator

A film bulk acoustic wave resonator (FBAR) was fabricated by using RF-sputtered aluminum nitride (AlN) between 400 nm-thick molybdenum (Mo) bottom and top electrodes. To reduce the acoustic loss of FBARs, an air gap cavity is fabricated below the membrane by a silicon deep-etch process. The sputtered 950 nm-thick AlN film was oriented in the (002) direction. The FBARs were measured by using a HP 8510C vector network analyzer in a wide frequency range of 0.5 ∼ 10.5 GHz. A resonance frequency was observed near 2 GHz as well as another, a third mode about 7 GHz. The minimum insertion loss was 0.056 dB at 1858 MHz. An equivalent circuit modeling regarding this FBAR was performed with modified Butterworth Van-Dyke (MBVD) models, wellknown piezoelectric equivalent circuit models. The calculated effective electromechanical coupling coefficient (keff ) was greater than 6.59 %.

Dielectric and piezoelectric properties of neodymium oxide doped lead zirconate titanate ceramics

The dielectric and electromechanical properties of lead zirconate titanate [Pb(Zr, Ti)O3] ceramic added with neodymium oxide have been systematically studied employing the vector impedance spectroscopic (VIS) technique. The specimens were prepared using the mixed oxide route by adding different mol% of Nd2O3 (01 to 7mol%) in [Pb(Zr, Ti)O3] near morphotropic phase boundary. Piezoelectric equivalent circuit parameters R, L, Ca in series and Cb in parallel have been determined by simulating /Z/ and Θ plots. Electromechanical coupling coefficients and strain constants for the radial modes show a peak at about 3 mol%, the dielectric constant peaks at about 1 mol% and voltage constants peak at about 0–75 mol% of Nd2O3.

The analysis of degradation phenomena in piezoelectric ceramics by equivalent circuit analysis method

The piezoelectric degradation phenomena of poled PZT ceramics were investigated relating to piezoelectric equivalent circuit elements. As a result, in the case of impressing mechanical shock on poled PZT degradation phenomena were explained by domain rearrangement, and in case of aging at room temperature, degradation phenomena were explained by space charge diffusion.

Dielectric and piezoelectric properties of lead zirconate titanate doped with chromium oxide

Vector impedance measurements of radial modes of thin disks (diameter 13 mm and thickness 1 mm) of Pb(Zr0.515Ti0.485)O3 doped with Cr2O3 have been carried out using an impedance analyzer. Piezoelectric equivalent circuit parameters R, L, Ca in series, and Cb in parallel have been measured by simulating ‖Z‖ and θ plots. Piezoelectric parameters for the first four radial modes have been obtained and it is found they peak at about 0.32 mol % of Cr2O3. The piezoelectric coupling coefficient Kp has been correlated with the dielectric constant. The dielectric quality factor Qe and mechanical quality factor Qm have been measured and (Qe/Qm)<1. ac conductivity follows a frequency power law with exponent p<1, suggesting that the hopping mechanism may be responsible for the dielectric loss.