• 센서학회지
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• 제27권4호
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• pp.269-274
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• 2018

High-sensitivity signal-to-noise ratio (SNR) microphones are essentially required for a broad range of automatic speech recognition applications. Piezoelectric microphones have several advantages compared to conventional capacitor microphones including high stiffness and high SNR. In this study, we designed a new piezoelectric membrane structure by using the finite elements method (FEM) and an optimization technique to improve the sensitivity of the transducer, which has a high-quality AlN piezoelectric thin film. The simulation demonstrated that the sensitivity critically depends on the inner radius of the top electrode, the outer radius of the membrane, and the thickness of the piezoelectric film in the microphone. The optimized piezoelectric transducer structure showed a much higher sensitivity than that of the conventional piezoelectric transducer structure. This study provides a visible path to realize micro-scale high-sensitivity piezoelectric microphones that have a simple manufacturing process, wide range of frequency and low DC bias voltage.

• 한국세라믹학회지
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• 제32권8호
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• pp.945-949
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• 1995

In order to investigate the performance of compression-type accelerometer on piezoelectric properties, PZT materials have been studied. The ring-shaped piezoelectric elements were prepared using commercial PZT powders by conventional ceramic process. Their estimated relative dielectric constant, piezoelectric charge constant (d33) and voltage constant (g33) values showed 390∼3400, (90∼593)×10-12 C/N and (19.5∼40.5)×10-3 V-m/N, respectively. The charge sensitivity of accelerometer is proportional to the piezoelectric charge constant value (d33) of PZT, but its voltage sensitivity is related with the piezoelectric voltage constant (g33). Since the mounted resonance frequency and sensitivity are dependent on the seismic mass as well as physical charateristics and size of PZT elements, the suitable considerations between two components are required for accelerometer's design.

• 제어로봇시스템학회논문지
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• 제6권4호
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• pp.239-246
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• 2000

This paper investigates optimal locations of piezoelectric actuators and sensors on a thin plate. To locate actuators and sensors properly is important in controlling modal vibrations well. A piezoelectric sensitivity index is introduced to select optimal locations for vibration control of each mode. The sensitivity expresses the efficiency of actuating and sensing modal forces according to locations of a piezoelectric material on a plate. The piezoelectric sensitivities for two types of plate, an all-clamped plate, and a free-free plate, are derived theoretically and are verified experimentally. Also, its usefulness Is experimentally shown to control vibration of the all-clamped plate with piezoelectric materials.

• 소음진동
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• 제8권2호
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• pp.267-273
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• 1998

This study aims at performing sensitivity analysis of piezoelectric smart structure for minimizing radiated noise from the structure, The structure consists of a flat plate on which disk shaped piezoelectric actuator is mounted, and finite element modeling is used for the structure. The finite element modeling uses a combination of three dimensional piezoelectric, flat shell and transition elements so thus it can take into account the coupling effects of the piezoelectric device precisely and it can also reduce the degrees of freedom of the finite element model. Electric potential on the piezoelectric actuator is taken as a design variable and total radiated power of the structure is chosen as an objective function. The objective function can be represented as Rayleigh's integral equation and is a function of normal displacements of the structure. For the convenience of computation, all degrees of freedom of the finite element equation is condensed out except the normal displacements of the structure. To perform the design sensitivity analysis, the derivative of the objective function with respect to the normal displacements is found, and the derivative of the norma displacements with respect to the design variable is calculated from the finite element equation by using so called the adjoint variable method. The analysis results are compared with those of the finite difference method, and shows a good agreement. This sensitivity analysis is faster and more accurate than the finite difference method. Once the sensitivity analysis program is used for gradient-based optimizations, one could achieve a better convergence rate than non-derivative methods for optimal design of piezoelectric smart structures.

• 센서학회지
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• 제29권1호
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• pp.45-50
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• 2020

Magnetoelectric (ME) composites were designed using the PMN-PZT single crystal and Ni foils; the properties and magnetic-field sensitivities of ME composites with different piezoelectric vibration modes (i.e., 31, 32, and 36 modes that depend on the crystal orientation of the single crystal) were compared. In the off-resonance condition, the ME coupling properties of the ME composites with the 32 and 36 piezoelectric vibration modes were better than those of the ME composites with the 31 piezoelectric vibration mode. However, in the resonance condition, the ME coupling properties of the ME composites were almost similar, irrespective of the piezoelectric vibration mode. Additionally, in the off-resonance condition (at 1 kHz), the magnetic-field sensitivity of the ME composites with the 36 piezoelectric vibration mode was up to 2 nT and those of the ME composites with the 31 and 32 piezoelectric vibration modes were up to 5 nT. These magnetic-field sensitivities are similar to those offered by conventional high-sensitivity magnetic-field sensors; the potential of the proposed sensor to replace costly and bulky high-sensitivity magnetic field sensors is significant.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1627-1632
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• 2000

Recently, piezoelectric materials have attracted considerable attention because of its self-sensing and actuating properties. To model smart structures, numerical modeling of structures with piezoelectric devices is essential. As many factors affect the performance of smart structures, optimization of these parameters is necessary. In this paper, the shape design sensitivity analysis of the 3D piezoelectric and structural elements is developed and shape optimization is performed. For the evaluation of the sensitivity, the finite element method is used. For the shape sensitivity, the domain velocity field is calculated. An acoustic cavity model is presented as a numerical example to study the feasibility of the formulation. The continuum sensitivity is compared with the results of the finite difference method by ANSYS. And the sequential linear programming (SLP) algorithm is used as the optimization algorithm.

• 소음진동
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• 제7권3호
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• pp.377-386
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• 1997

A cantilever type piezoceramic vibration sensor was developed that could make up for the short-comings of current vibration sensors, such as high price, low sensitivity, and complex structure. For the design, in conjunction with piezoelectric constitutive equations, we derived full analytic response equations of the piezoelectric bimorph sensor to external forces. The external forces were supposed to take the form of either step or sinusoidal force. Based on the results, actual piezoelectric vibration sensors were fabricated and tested for verification of the theoretical results. Further, comparison of the performance of the developed sensor was made with that of a commercially available representative vibration sensor so that quantitative evaluation of its sensitivity could be made. The sensor developed in this work showed excellent sensitivity and thermal stability in addition to the merits of simple structure and low fabrication cost in comparison with conventional mass-loaded piezoelectric sensors.

• Transactions on Electrical and Electronic Materials
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• 제18권2호
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• pp.78-88
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• 2017

Cantilever beam MEMS piezoelectric accelerometers are the simplest and most widely used accelerometer structure. This paper discusses the design of a piezoelectric accelerometer exclusively for SHM applications. While such accelerometers need to operate at a lower frequency range, they also need to possess high sensitivity and low noise floor. The availability of a simple model for deflection, charge, and voltage sensitivities will make the accelerometer design procedure less cumbersome. However, a review of the open literature suggests that such a model has not yet been proposed. In addition, previous works either depended on FEM analysis or only reported on the fabrication and characterization of piezoelectric accelerometers. Hence, this paper presents, for the first time, a simple analytical model developed for the deflection, induced voltage, and charge sensitivity of a cantilever beam piezoelectric accelerometer.The model is then verified using FEM analysis for a range of different cases. Further, the model was validated by comparing the induced voltages of an accelerometer estimated using this model with experimental voltages measured in the accelerometer after fabrication. Subsequently, the design of an accelerometer is demonstrated for SHM applications using the analytical model developed in this work. The designed accelerometer has 60 mV/g voltage sensitivity and 2.4 pC/g charge sensitivity, which are relatively high values compared to those of the piezoresistive and capacitive accelerometers for SHM applications reported earlier.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.211-216
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• 1995

In this study, the piezoelectric ceramics/polymer composite transducers with 1-3 connectivity have been studied. A piezoelectric ceramics PZT prepared by Wet-Dry Combination method was used as a filler in polymer matrix Eccogel. We've got the pulse-echo response for 1-3 type piezc-electric composite transducers in water. It was shown that the transmitting and receiving sensitivity of 1-3 type piezoelectric composite transducers could be improved in comparison with that- of solid PZT transducers. The reason is for that 1-3 type Piezoelectric composites have low dielectric constant and density. There was in a good agreement between the resonant frequencies calculated from one period and observed results on the Ultrasonic Transducer Analyzer. According to these results we could be figured out the distance in water by virture of the pulse-echo response.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.335-342
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• 2005

Using higher order Mindlin plates and piezoelectric materials, eigenvalue problems are considered. Since piezoelectric crystal resonators produce a proper amount of electric signal for a thickness-shear frequency, the objective is to decouple the thickness-shear mode from the others. Design variables are the bulk material densities corresponding to the mass of masking plates for electrodes. The design sensitivity expressions for the thickness-shear frequency and mode shape vector are derived using direct differentiation method(DDM). Using the developed design sensitivity analysis (DSA) method, we formulate a topology optimization problem whose objective function is to maximize the thickness-shear component of strain energy density at the thickness-shear mode. Constraints are the allowable volume and area of masking plate. Numerical examples show that the optimal design yields an improved mode shape and thickness-shear energy.