• 센서학회지
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• 제8권3호
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• pp.211-218
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• 1999

This paper describes the application of a coupled finite element-boundary element method (FE-BEM) to obtain the steady-state response of a piezoelectric transducer. The particular structure considered is a PZT4 disc-typed projector. The projector is three-dimensionally simulated to transduce applied electric charge on axial surfaces of the piezoelectric disc to acoustic pressure in air or in water. The directivity pattern of the acoustic field formed from the projected sound pressure is also simulated. And the displacement of the disc caused by the externally applied electric charge is shown in temporal motion. The coupled FE-BE method is described in detail.

• 한국생산제조학회지
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• 제21권3호
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• pp.362-367
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• 2012

Though a micro pump is a crucial element in miniaturized bio-fluidic systems or drug delivery systems, most of the conventional micro pumps still have some limitations to miniaturize their controller system and to obtain the sufficient back pressure which can rise over the inner pressure of human body or experimental animals. In this paper, to overcome these limitation, a new PZT disc and its controller were designed and fabricated to get the sufficient flowrate and the back pressure with guaranteeing embeddability of the controller into pumping body. The amplitudes of the disc deflections were as large as 40 ${\mu}m$ at 200 V - 100 Hz condition. As results of experiments, the flow rate and the back pressure increase when the frequency increases. The obtainable maximum flow rate and back pressure are 5.2 ml/min at 95 Hz and 13.14 kPa at 90 Hz respectively.

• 한국음향학회지
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• 제11권2호
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• pp.28-37
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• 1992

본 연구에서는 압전 특성이 우수한 PZT계 압전세라믹스를 원판상으로 박판화하여 금속 진동판에 부착시킨 PZT/Metal음향변환기를 제작하였다. 이 때 압전 세라믹스를 박판화하기 위해 'tape casting 방법‘을 사용했으며, 제작된 PZT/Metal 음향 변환기를 압전 부자, 압전 스피커등의 소자에 응용 시키기 위해 음향특성을 연구하였다. 연구 결과, 세라믹스의 압전 계수($d_{31}$)이 증가함에 따라 레벨(dB)이 -6dB에서 - 14dB로 증가된다. 음향 변환기의 직경비 ${\eta}$가 0.7-08이고, 두꺼비 (${\beta}$)가 1일 때 최적 음압 특성을 나타냈으며, 음압은 -15~-16dB정도이었다.

• 한국생산제조학회지
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• 제21권3호
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• pp.355-361
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• 2012

Though a micro pump is a crucial element in miniaturized bio-fluidic systems or drug delivery systems, it has some intrinsic disadvantages such as backward flow, pulsation of flow, low repeatability and producibility, and high cost. To overcome these limitation, a PZT disc actuated micro pump including a novel ring-shaped multi-flap check valve is introduced. To enhance the performance of the micro pump, the static behaviour of flap valve module and the micro fluidic behavior of fluids are numerically modelled and analyzed. As results of the numerical analysis, the optimal dimension and configuration of the ring-shaped multi flap valve are $1{\times}0.05$ mm and 2 (inlet side)${\times}1$ (outlet side) type. The obtained maximum flow rates and flow resolution are about 90 ml/min and 30 ${\mu}l$/stroke respectively.

• Smart Structures and Systems
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• 제22권3호
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• pp.259-276
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• 2018

This paper studies the energies and energy release rate (ERR) for the initially rotationally symmetric compressed (or stretched) in the inward (outward) radial direction of the PZT/Elastic/PZT sandwich circular plate with interface penny-shaped cracks. The investigations are made by utilizing the so-called three-dimensional linearized field equations and relations of electro-elasticity for piezoelectric materials. The quantities related to the initial stress state are determined within the scope of the classical linear theory of piezoelectricity. Mathematical formulation of the corresponding problem and determination of the quantities related to the stress-strain state which appear as a result of the action of the uniformly normal additional opening forces acting on the penny-shaped crack's edges are made within the scope of the aforementioned three-dimensional linearized field equations solution which is obtained with the use of the FEM modelling. Numerical results of the energies and ERR and the influence of the problem parameters on these quantities are presented and discussed for the PZT- 5H/Al/PZT-5H, PZT-4/Al/PZT-4, $BaTiO_3/Al/BaTiO_3$ and PZT-5H/StPZT-5H sandwich plates. In particular, it is established that the magnitude of the influence of the piezoelectricity and initial loading on the ERR increases with crack radius length.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.283-286
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• 2000

In this study, the acoustic transducer of a thin circular disc-type with PZT/Metal was manufactured. The piezoelectric transducer with 200kHz resonance frequency was designed by considering the sharp directivity and the sound pressure. The dielectric and piezoelectric properties of 0.5 weight percent $MnO_2$ and NiO doped $0.1Pb(Mg_{1/3}Nb_{2/3})O_3-0.45PbTiO_3-0.42PbZrO_3$ ceramics were investigated aiming at acoustic transducer applications. Also, the acoustic characteristics of a thin circular disc-type with metal-piezoceramics have been Investigated.

• International Journal of Concrete Structures and Materials
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• 제9권3호
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• pp.307-321
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• 2015

The primary objective of this study is to investigate the feasibility of an innovative surface-mount sensor, made of a piezoelectric disc (PZT sensor), as a consistent source for surface wave velocity and transmission measurements in concrete structures. To this end, one concrete slab with lateral dimensions of 1500 by 1500 mm and a thickness of 200 mm was prepared in the laboratory. The concrete slab had a notch-type, surface-breaking crack at its center, with depths increasing from 0 to 100 mm at stepwise intervals of 10 mm. A PZT sensor was attached to the concrete surface and used to generate incident surface waves for surface wave measurements. Two accelerometers were used to measure the surface waves. Signals generated by the PZT sensors show a broad bandwidth with a center frequency around 40 kHz, and very good signal consistency in the frequency range from 0 to 100 kHz. Furthermore, repeatability of the surface wave velocity and transmission measurements is significantly improved compared to that obtained using manual impact sources. In addition, the PZT sensors are demonstrated to be effective for monitoring an actual surface-breaking crack in a concrete beam specimen subjected to various external loadings (compressive and flexural loading with stepwise increases). The findings in this study demonstrate that the surface mount sensor has great potential as a consistent source for surface wave velocity and transmission measurements for automated health monitoring of concrete structures.

• 한국세라믹학회지
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• 제20권3호
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• pp.227-235
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• 1983

The dielectric and piezoelectic properties in which $(Zr_{0.52} Ti_{0.48})^{+4}$ ions of $Pb(Zr_{0.52} Ti_{0.48})O_3$ are partially substituted for $W^{+6}$ ions were studied. $ZrTiO_4$ was made by coprecipitation. The specimens of disc shape were sintered respectively at 1180$^{\circ}$to 130$0^{\circ}C$ at an intervals of 2$0^{\circ}C$ for 1 hour. The optimum sintering temperature were found to be between 126$0^{\circ}C$ and 128$0^{\circ}C$. PZT solid solutions sintered had the tetragonal structure with c/a=1.025$\pm$0.005 and theoretical densities incre-ased from 8.02 to 8.17g/cm3 with increasing the amount of the partial substitution of $(Zr_{0.52} Ti_{0.48})^{+4}$ ion for $W^{+6}$ ion The grain size and curie temperature decreased with increasing the amount of $WO_3$ while the dielectric constant increased. When $(Zr_{0.52} Ti_{0.48})^{+4}$ ion was substituted for 1 mole% of $W{+6 ]$ion the planar coupling coefficient$(K_P)$ was as high as 0.58 But as the amount of $WO_3$ increased the mechanical quality factor(Qm) decreased considerably.

• 비파괴검사학회지
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• 제18권3호
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• pp.163-171
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• 1998

터빈 디스크에서 발생하는 결함에 대한 초음파탐상기술을 확립하기 위하여 초음파탐촉자의 근/원거리 음장 및 지향성에 대하여 연구하였다. 영광원자력 LP터빈 No. 6 디스크와 동일하게 대비시험편을 제작하였고 터빈로타 디스크의 초음파탐상에 사용된 5MHz PZT 압전탐촉자의 직경에 따른 근/원거리 음장 및 지향성을 계산하고 실험을 통하여 확인하였다. 쐐기와 디스크로 구성된 실험계에서 bore면에 깊이 2mm 및 4mm 인공결함을 지닌 시편과 직경이 0.5inch이고 중심 주파수 5MHz인 초음파탐촉자를 이용하여 계산 및 실험을 수행하였고 그 결과를 비교, 분석하였다. Keyway 영역에 발생한 결함의 탐상능력을 평가하기 위하여 내부의 53mm 및 75mm 지점에 초음파탐촉자를 두고서 $45^{\circ}$ 및 $90^{\circ}$ 경사각 초음파탐촉자를 설치한 경우를 가정하여 결함의 탐상영역을 결정하였다.

• Smart Structures and Systems
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• 제19권2호
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• pp.163-179
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• 2017

The axisymmetric buckling delamination of the Piezoelectric/Metal/Piezoelectric (PZT/Metal/PZT) sandwich circular plate with interface penny-shaped cracks is investigated. The case is considered where open-circuit conditions with respect to the electrical displacement on the upper and lower surfaces, and short-circuit conditions with respect to the electrical potential on the lateral surface of the face layers are satisfied. It is assumed that the edge surfaces of the cracks have an infinitesimal rotationally symmetric initial imperfection and the development of this imperfection with rotationally symmetric compressive forces acting on the lateral surface of the plate is studied by employing the exact geometrically non-linear field equations and relations of electro-elasticity for piezoelectric materials. The sought values are presented in the power series form with respect to the small parameter which characterizes the degree of the initial imperfection. The zeroth and first approximations are used for investigation of stability loss and buckling delamination problems. It is established that the equations and relations related to the first approximation coincide with the corresponding ones of the three-dimensional linearized theory of stability of electro-elasticity for piezoelectric materials. The quantities related to the zeroth approximation are determined analytically, however the quantities related to the first approximation are determined numerically by employing Finite Element Method (FEM). Numerical results on the critical radial stresses acting in the layers of the plate are presented and discussed. In particular, it is established that the piezoelectricity of the face layer material causes an increase (a decrease) in the values of the critical compressive stress acting in the face (core) layer.