Piezoelectric Ring Research Articles

The effect of multidirectional bias magnetic fields on the converse magnetoelectric response of multiferroic concentric composite ring

A composite multiferroic ring was characterized under two orthogonal bias magnetic fields while electrically loaded near resonance to measure the circumferential converse magnetoelectric (CME) response. The composite multiferroic structure consisted of an inner magnetostrictive Terfenol-D ring with an axially aligned preferred magnetocrystalline axis bonded to a radially polarized outer piezoelectric poled lead zirconate titanate ring to form a concentric ring structure. A single uniform bias magnetic field was varied from zero to beyond magnetic saturation while the composite ring's axial alignment was changed from perpendicular to parallel with respect to the bias magnetic field direction. The change in the ring orientation thus subjected the ring to two orthogonal bias magnetic fields, whose strengths were calculated based on the orientation angle. The overall CME behavior was found to be largely correlated with the perpendicular magnetic field strength assisted with the shape anisotropy of the ring structure favoring magnetization along the longest axis. Nonetheless, the parallel magnetic field had a notable contribution to the CME response by enhancing the magnetization in the preferred axial direction and activating other unique magnetocrystalline axes. In all, the CME behavior with respect to two orthogonal bias magnetic fields is characterized by an interplay of magnetocrystalline and shape anisotropies bolstered by the parallel and perpendicular magnetic fields.

Resolution improvement for digital closed loop resonator micro-optic gyro based on tunable resonator

In the resonator micro-optic gyro (RMOG) frequency locking loop, digital-to-analog converter quantization error leads to low-accuracy laser tuning, causing frequency locking and rotation sensing dead zones. This paper proposes a planar waveguide resonator (PWR) frequency locking scheme with a piezoelectric (PZT) ring to tune the PWR resonant frequency to track and lock to the laser frequency. The proposed scheme achieved PZT-PWR Q = 4 × 107 and frequency tuning coefficient = 1.124 MHz / V. Direct comparison on an RMOG device experimentally verified the proposed scheme reduced frequency locking noise to 0.25 deg / s and improved gyro resolution from 1 to <0.05 deg / s.

Development of an Omni-Directional Shear Horizontal Wave Transducer Based on a Radially Poled Piezoelectric Ring

For the inspection of large plate-like structures, the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspection area without blind zones. In comparison with Lamb waves, the shear horizontal (SH) wave is more promising because its fundamental mode is non-dispersive. In this work, we proposed an omni-directional SH wave piezoelectric transducer (OSH-PT) based on a radially poled $$\hbox {d}_{24}$$ -mode PZT ring. Both the finite element simulations and experiments were carried out to demonstrate its performance in generating and receiving $$\hbox {SH}_{0}$$ wave. Results showed that the radially poled OSH-PT could generate single-mode $$\hbox {SH}_{0}$$ wave and receive $$\hbox {SH}_{0}$$ wave only over a wide frequency range from 70 to 200 kHz. The obtained signal-to-noise ratio can reach up to 26 dB in generation and 24 dB in reception. The omni-directivity of this OSH-PT is also very good with the deviation only about 6% in both generation and reception of $$\hbox {SH}_{0}$$ wave. Considering its easy fabrication, low cost and superior performances, this proposed OSH-PT may promote the applications of $$\hbox {SH}_{0}$$ wave-based inspection in structural health monitoring and nondestructive testing.

Study on the broadband piezoelectric ceramic transducer based on radial enhanced composite structure

A new type of broadband piezoelectric ceramic transducer is developed and analyzed. The transducer is composed of two radial enhanced composite vibrators with different resonance frequencies stacked along the axial direction. Each vibrator consists of a piezoelectric ceramic stack polarized in the thickness direction and a metal tube, and they are connected and excited to vibrate in the radial direction. On the basis of the radial vibrations of the piezoelectric ceramic thin ring and the metal tube, the electromechanical equivalent circuit of the transducer is derived and the input impedance of the transducer is obtained. The relationship between the resonance frequency and the geometrical dimensions of the transducer is analyzed. The new type of transducer is simulated using the ANSYS software. The simulated resonance frequencies of the transducer are in good agreement with the theoretical results. The transducer exhibits broadband characteristics because of the double stacking of vibrators with different resonance frequencies, and the transducer can be driven under high power because of its radial enhanced composite structure.

Full simulation of a piezoelectric double nozzle flapper pilot valve coupled with a main stage spool valve

This paper develops a detailed simulation model, realized by the software Simscape, which can be a powerful tool to analyze the performance of a double nozzle flapper valve actuated by a piezoelectric ring bender. The particularity of this valve is that the use of the torque motor and flexure tube is avoided, thus reducing the complexity, manufacturing time and cost of the valve assembly. The model accounts for all the real phenomena present in the valve, such as fluid compressibility and fluid viscosity. The viability of the valve concept is validated by step tests simulated at different valve openings. It is shown that the response time obtained for a supply pressure of 210 bar and necessary to reach 90% of the maximum opening degree (corresponding to a maximum spool position of 1mm and maximum flow rate of 60 l/min) is only 6 ms, which is comparable with typical commercially available double nozzle flapper valves, but with the advantage of having removed critical components such as the torque motor and the flexure tube.

Modified Dual Piezo Configuration for Improved Structural Health Monitoring Using Electro-Mechanical Impedance (EMI) Technique

This paper presents a new variant of the electro-mechanical impedance (EMI) technique encompassing sensor-actuator dual configuration for improved damage assessment. In this arrangement, called as dual piezo configuration (DPC), an outer piezoelectric ring acts as the actuator and an inner piezoelectric disc as the sensor. The configuration yields better results than the conventional EMI configuration employing the same piezo patch as the sensor as well as the actuator. This paper presents a more practical and modified version of DPC entailing a group of normal commercially available PZT patches. The piezo sensor configurations evaluated in the paper are: (a) single piezo configuration (SPC), which is conventionally employed in the EMI technique; (b) dual piezo configuration (DPC), which consists two different patches in ring type configuration; and (c) modified dual piezo configuration (MDPC), which uses four outer piezo patches for the actuation and a centrally located piezo patch for the sensing purpose. The paper first covers the comparison of the three configurations through finite element method (FEM), using an aluminum block of dimensions 48 × 48 × 10 mm as the host structure and lead zirconate titanate (PZT) patches of size 10 × 10 × 0.3 mm, analyzed through coupled field analysis. The simulation study is followed by an experiment on the aluminum block of the same size and finally on a prototype steel plate of dimensions 1200 × 970 × 8 mm. Simulation results and experimental data prove that the proposed MDPC is much more sensitive to the occurrence than the conventional SPC. Also, MDPC ensures much larger zone of influence as compared to the conventional SPC as well as the DPC and it commands higher sensitivity. Hence, it can be employed on the large structures to detect damage, which is not possible by using the SPC which may warrant very large number of sensors. Thus, the proposed MDPC approach can be practically employed to detect the damage in large civil, mechanical and aerospace structures.

Ultrasound liquid crystal lens

A variable-focus lens using a combination of liquid crystals and ultrasound is discussed. The lens uses a technique based on ultrasound vibration to control the molecular orientation of the liquid crystal. The lens structure is simple, with no mechanical moving parts and no transparent electrodes, which is helpful for device downsizing; the structure consists of a liquid crystal layer sandwiched between two glass substrates with a piezoelectric ring. The tens-of-kHz ultrasonic resonance flexural vibration used to excite the lens generates an acoustic radiation force on the liquid crystal layer to induce changes in the molecular orientation of the liquid crystal. The orientations of the liquid crystal molecules and the optical characteristics of the lens were investigated under ultrasound excitation. Clear optical images were observed through the lens, and the focal point could be controlled using the input voltage to the piezoelectric ring to give the lens its variable-focus action.

A multilayered-cylindrical piezoelectric shear actuator operating in shear (d15) mode

In this work, a multilayered-cylindrical piezoelectric shear actuator (MCPSA) operating in the d15 shear mode was presented for precision actuation under a large mechanical load. The actuator was made of Pb(Zr,Ti)O3 (PZT-51) piezoelectric ceramic rings, which were concentrically assembled together in electrically parallel connection with alternately positive and negative polarizations along the axial direction. Experimental results show that the acquired displacement amplitude at the center of the actuator along the axial direction is around 6.5 μm under the 1 Hz applied voltage of 400 Vpp/mm, and it stayed stably under a mechanical load up to 18 N, which is 7 times larger than that of the previously reported d15 shear actuator. The proposed actuator also shows good displacement linearity with a high resolution of 0.1 μm in responding to a step voltage, indicating its great potential for precision actuation under a large mechanical load.

Dynamic stiffness control of piezoelectric ring based on finite difference and hybrid programming simulation

Abstract During the flight of hypersonic aircraft, stiffness of some local annular region needs to be enhanced. For the stiffness control system of the ring laminated with piezoelectric sensor and actuator, an annular multi-modes smart element hybrid programming simulation model has been developed to simulate and analyze the closed-loop stiffness control of independent mode. The dynamic partial differential equations of piezoelectric ring are transformed into ordinary differential equations containing sensing and control effect matrix by finite difference method. To solve the big-matrix calculation and multiple iteration problem, hybrid programming smart element simulation system is developed with C++ and MATLAB. The cosine type sensor/actuator controlling the dynamic stiffness of independent mode with displacement/acceleration feedback is employed to be a simulation example. Simulations and analysis are conducted in different conditions of differential density, integral time step and gain ratio, and relatively satisfying result is obtained. Finally, the experimental verification is carried out. This method provides a new solution to the big-data discrete simulation and analysis of complex rotary surface smart structure system.

A new lumped parameter model for the design of the free-flooded ring transducer

The free-flooded ring (FFR) transducer is the well-known low-frequency sound sources in underwater because of its broad operating frequency bandwidth and relatively small size. Many previous studies have been performed that predict the characteristics of an FFR transducer using an equivalent circuit model (ECM), a type of lumped parameter model (LPM) because an ECM is widely used to understand the properties of such transducers in the design process. However, it is quite difficult to predict the characteristics of an FFR transducer because the acoustic field is generated from its top and bottom openings, connected by the inner fluid, as well as the cylindrical ring surface. In this study, the authors investigated an ECM of an FFR transducer. The ECM consists of three parts: the piezoelectric ring, the cylindrical cavity, and the radiation load. In addition, an LPM which can consider mutual radiation loads was proposed to improve the accuracy of the model. The proposed models were compared and verified using commercial finite element method (COMSOL Multiphysics). We confirmed that LPM can predict characteristics of FFR transducer more accurately than ECM. [This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (Grant No. 2016R1E1A2A02945515).]

Analytical model for the energy harvesting of a spherical sensor from ambient vibrations

In this work an analytical model for the energy harvesting of an acoustic spherical sensor has been developed in the context to make it autonomous. Our spherical sensor is composed of two half-spheres of Plexiglas and a piezoelectric ring of PZ26 that can be used as exciter or sensor. For the analytical model, the piezoelectric ring was modeled using two primary modes of vibration: thickness and radial. For each mode, the ring is described by an equivalent electromechanical model which connects the mechanical part (forces and velocities) to the electrical part (voltage and current). The proposed paper theoretical model enables building a global electromechanical circuit in order to simulate the total harvested voltage response.

Analysis of Piezoelectric Ring Finite Difference Simulation with Dynamic Stiffness Control

Analysis of Piezoelectric Ring Finite Difference Simulation with Dynamic Stiffness Control

Multiphysics topology optimization for piezoelectric acoustic focuser

The application of piezoelectric materials allows many advantages such as reducing the number of parts and manufacturing cost of a mechanical system. Despite these merits, the performance predictions and optimization of piezoelectric-material-based devices are challenging because of the mutual coupling between electricity and mechanics. The analysis and the optimization become more challenging when acoustics are to be coupled with piezoelectric-material-based devices. In the present study, the mutual couplings among electric, mechanics, and acoustics are simulated and its applications for the topology optimization of an acoustic energy focuser are presented. Owing to the local optima issue, some blurred and unsuccessful layouts are obtained. To overcome this issue and impose the manufacturing constraint, a modified morphology density filter is also developed. With the presented approach, it is possible to determine some optimized piezoelectric rings to focus acoustic energy. Compared with the existing design methods, some better designs in terms of objective value can be obtained by the present approach.

Wide band underwater acoustic transducer for stacked 2-2 piezoelectric composite material tube

ABSTRACTA kind of high frequency wideband underwater acoustic transducer is developed, this transducer is formed by 2-2 type piezoelectric composite tube which is composed of double ring stacked along the axial direction. Through the radial cutting piezoelectric ceramic ring, filled with epoxy resin, samples polished, coated electrode and a series of process, the piezoelectric composite ring is prepared, then, the ring with the same outer diameter and different wall thickness is stacked in the axial direction. A double ring stack piezoelectric composite sensor is prepared, after pouring waterproof permeable layer, the transducer is made. Underwater performance test results show that the resonant frequency of transducer is 410 kHz, the maximum transmit voltage response is 150 dB, the -3dB bandwidth reaches 60 kHz, The bandwidth of the transducer is expanded by the method of composite and dual mode coupling.

A study of determination of dynamic viscosity in liquids using radial mode piezo-resonator

ABSTRACTAn investigation on determination of viscosity based on radial mode resonance of a piezoelectric ceramic ring transducer operating at 32.5 kHz is reported. The change in its resonant frequency and in the half peak bandwidth have been measured with the disc vibrating in air, water, pure glycerine and a glycerine-water mixture. An improved configuration of coupling the transducer to the liquid medium has been used so that it has semi-infinite loading of its front face. Also, a correction in the bandwidth eliminating the mechanical loss inherent in the piezoelectric element has been made, which has improved the accuracy of viscosity determination.

A new lumped parameter model for the design of the free-flooded ring transducer

The free-flooded ring (FFR) transducer is the well-known low-frequency sound sources in underwater because its operating frequency bandwidth is broad and relatively small size. Previous researches were preformed to predict the characteristics of FFR transducers using ECM which is a type of LPM because ECM is widely used to understand its characteristics in transducer design process. However, it is hardly to predict the characteristics of an FFR transducer because the acoustic field is generated from its top and bottom openings, connected by the inner fluid, as well as the cylindrical ring surface. Here, the authors investigated an ECM of an FFR transducer consisting of three parts: the piezoelectric ring, the cylindrical cavity, and the radiation load. In addition, an LPM which can consider mutual radiation loads was proposed to improve the accuracy of the model. The proposed models were verified using commercial finite element method (COMSOL Multiphysics). It was confirmed that LPM could predict characteristics of FFR transducer more accurately than ECM. [Work supported by NRF 2016R1E1A2A02945515).]

A uniform-sensitivity omnidirectional shear-horizontal (SH) wave transducer based on a thickness poled, thickness-shear (d15) piezoelectric ring

The fundamental shear horizontal (SH0) wave in plates is of great importance in the field of nondestructive testing (NDT) and structural health monitoring (SHM) since it is the unique non-dispersive guided wave mode. For practical applications, a phased array system based on omnidirectional SH0 wave transducers is most useful as it can cover a wide range of a plate. However, so far very few omnidirectional SH wave transducers have been developed. In this work, we proposed an omnidirectional SH wave piezoelectric transducer (OSH-PT) based on a thickness poled piezoelectric ring. The ring is equally divided into twelve sectors and the electric field is circumferentially applied, resulting in a new thickness-shear (d15) mode. Finite element analysis shows that the proposed OSH-PT can excite single-mode SH0 wave and receive the SH0 wave only. Experiments were then conducted to examine the performance of the proposed OSH-PT. Results indicated that it can generate and receive single-mode SH0 wave in a wide frequency range with nearly uniform sensitivities along all directions. Considering its quite simple configuration, compact size and low cost, the proposed OSH-PT is expected to greatly promote the applications of SH waves in the field of NDT and SHM.

2층 압전 환판 초음파 트랜스듀서의 진동 특성

2층 압전 환판 초음파 트랜스듀서의 진동 특성

A lumped parameter model of the single free-flooded ring transducer.

A free-flooded ring (FFR) transducer can generate low-frequency sound in a small device and has a wide operating frequency bandwidth. Many studies have been performed that can predict the characteristics of an FFR transducer using analytical techniques and an equivalent circuit model (ECM), and methods to predict properties using numerical simulations have recently been developed. However, an ECM, a type of lumped parameter model (LPM), is still widely used to interpret the properties of such transducers in the design process. In this study, the authors investigated an ECM of an FFR transducer. The ECM consists of three parts: the piezoelectric ring, the cylindrical cavity, and the radiation load. Moreover, it can be included readily in a circuit to drive an FFR transducer. Additionally, an LPM was proposed, considering the mutual radiation loads, to improve the accuracy of the model. Each model was tested in comparisons with the finite element method; it was confirmed that an LPM could predict the properties of an FFR transducer with much better accuracy than an ECM. The LPM developed can save much time in designing FFR transducers.

Versatility of Piezoelectric Ring Actuator Technique (P-RAT) for Characterization of Cement Paste and Mortar

Abstract Piezoelectric ring-actuator technique (P-RAT) enables the measurement of shear wave (S-wave) velocity (Vs) of a cement-based material, which is directly related to its elastic shear modulus (G). The P-RAT can produce high quality signals with low energetic primary waves (P-waves), thus resulting in precise measurements of S-wave velocity. This paper checked the reliability of the P-RAT to monitor the setting time using the frequency spectrum of the received signals. A possibility of using the P-RAT to monitor the elastic shear modulus of the cement pastes and mortars starting at an early age was studied. This paper also discussed signal processing techniques, including phase shift correction and the first arrival time that can be used to determine the variation of Vs of cement paste and mortar, which can be interpreted to determine setting time. In total, 16 cement paste and mortar mixtures proportioned with different water-to-cement ratios (w/c), high-range water-reducing admixture dosages, and sand volume fractions were investigated. In addition to Vs measurements, the frequency content of the received signals was shown to offer another alternative to determine setting time of cement paste and mortar. To monitor the elastic shear modulus of cement paste and mortar from 1 up to 56 days, a test setup with two P-RAT sensors mounted on opposite sides of a clamping vice was developed for measuring Vs of different hardened material in shape and thickness.