• Proceedings of the KSME Conference
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• 2005.11a
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• pp.149.1-149.1
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• 2005

• Journal of KSNVE
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• v.6 no.1
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• pp.11-19
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• 1996

지금까지의 항공기 날개에 공력 탄성학적 제어를 위해 압전재료를 작동기로 사용하는 연구는 아직은 완전하지 못하지만 실용화 가능성을 조사하기 위해 집중적인 투자가 행해지고 있다. 본 글에서 언급한 예 외에도 압전재를 이용 날개의 익형을 능동적으로 조절함으로써 천음속에서의 저항을 줄이기 위한 연구(transonic drag reduction with piezos), 압전재로 작동하는 제어면을 부착하여 헬리쿱터 블레이드 의 진동을 제어하기 위한 실험적 연구, 항공기 외부 장착물에 의해 발생되는 불안정 성을 제어하기 위한 압전작동기를 사용한 pylon decoupler 설계 등 다양한 분에에서 연구가 되고 있다. 하지만 아직까지는 제어에 필요한 충분한 제어력을 얻는 문제, 주 구조물과 압전재료의 강성도의 차이, 가용한 압전재의 실용화, 내구성 문제 등 항공 기에의 응용을 위한 새로운 재료의 개발이 요구되고 있다. 그리고 사용에 필요한 전력을 공급하는 문제는 지상에서 작동되는 시스템과는 달리 항공기에서는 해결해야 될 큰 문제점이며, 이에 대한 연구가 요구되고 있으며, 실용 가능성이 보일 경우 재료의 내구성, 제어 성능, 번개 등 외력에 대한 손상 예측 등 광범위한 연구가 이어 질 것으로 예측된다.

• Composites Research
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• v.15 no.3
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• pp.52-61
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• 2002

For the aerothermoelastic analysis of cylindrical piezolaminated shells, geometrically nonlinear finite elements based on the multi-field layerwise theory hale been developed. Applying a Han Krumhaar's supersonic piston theory, supersonic flutter analyses are performed for the cylindrical piezolaminted shells subject to thermal stresses and deformations. The possibility to increase flutter boundary and reduce thermoelastic deformations of piezolaminated panels is examined using piezoelectric actuations. Results show that active piezoelectric actuations can effectively increase the critical aerodynamic pressure by retarding the coalescence of flutter modes and compensating thermal stresses.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.37-44
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• 2004

This paper deals with the performance analysis of LIPCA(Light-weight Piezo-Composite actuator) including the material nun-linearity of the embedded 3203HD PZT wafer. For this analysis, we used a piezo-shell element code based on a nine-node assumed strain shell element formulation. The material non-linearity was implemented in the formulation due to a large observed discrepancy between the measured displacement and the computed actuation displacement based on the linear analysis. An experimentally extracted piezo-strain function of the PZT wafer and incremental formulation were incorporated into the linear finite element code to improve the accuracy of the estimated actuation displacement of the LIPCA. The non-linear piezo-shell program was used to predict the non-linear performance of the LIPCA. The simulated actuation displacement from the non-linear code showed much better agreement with the measured data.

• Composites Research
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• v.15 no.5
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• pp.7-13
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• 2002

The piezoelectric thin film sensor has good characteristics to observe the impact responses of composite structures. The capabilities for monitoring impact behavior of Gr/Ep laminates subjected to damage-induced impact using the PVDF(polyvinylidene fluoride) film sensor were examined. For a series of low-velocity impact tests from low energy to damage-induced energy, simulated sensor signals were compared with measured signals and the PVDF film sensor. Local impact damages(matrix cracking and delamination) were found at three impact tests, but the measured signals agreed well with the simulated sensor signals based on the linear relationship between the impact forces and the PVDF film sensor signals. And the inverse technique was applied to reconstruct the impact forces using the PVDF film sensor signals. Most of reconstructed impact forces had good agreement with the measured forces. The comparison results showed that the local damage due. to low-velocity impact didn't disturb the global impact responses of composite laminates and the reconstruction of impact forces from PVDF sensor signals wasn't affected by the local damage.

• Composites Research
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• v.13 no.6
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• pp.47-54
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• 2000

One promising method for impact detection of composite structures is based on the use of piezopolymer thin fim (PVDf) sensor. In this paper, the relationship between the contact force and the signals of the attached strain gage and PVDF sensor to the composite plate subjected to low-velocity impact were derived. The relation for the open circuit and short circuit voltage of PVDF sensor was derived based on the equivalent circuit model of the piezoelectric sensor. The work was then extended to include experimental investigation into the use of short circuit voltage of PVDF sensor without using charge amplifier to detect low-velocity impact. The natural frequencies and damping ratio of the composite plate obtained from the vibration test were used to modify the analytical model and therefore the differences between measured and simulated signal of the modified analytical model in both forward and backward problem were considerably reduced. The reconstructed contact force and simulated sensor signals agreed well with the measured contact force, strain gage signal, and PVDF sensor singanl.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.150-159
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• 2002

The possibility of a broadband noise reduction of piezoelectric smart panels is experimentally studied. Piezoelectric smart panel is basically a plate structure on which piezoelectric patch with shunt circuits is mounted and sound absorbing material is bonded on the surface of the structure. Sound absorbing materials can absorb the sound transmitted at mid frequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. To be able to tune the piezoelectric shunt circuit, the measured electrical impedance model is adopted. Resonant shunt circuit composed of register and inductor in stories is considered and the circuit parameters are determined based on maximizing the dissipated energy through the circuit. The transmitted noise reduction performance of smart panels is investigated using an acoustic tunnel. The tunnel is a square crosses sectional tunnel and a loud speaker is mounted at one side of the tunnel as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across the panels is measured. Noise reduction performance of a double smart panel possessing absorbing material and air gap shows a good result at mid frequency region except the first resonance frequency. By enabling the piezoelectric shunt damping, noise reduction is achieved at the resonance frequency as well. Piezoelectric smart panels incorporating passive method and piezoelectric shunt damping are a promising technology for noise reduction in a broadband frequency.

• Composites Research
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• v.27 no.4
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• pp.141-145
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• 2014

This paper presents a structural health monitoring method using piezoelectric paint sensor designed for an impact sensor. The piezoelectric paint sensor can be flexibly deposited onto most structural surfaces in a thin form of the paint, and measure impact signals without any external device such as a power amplifier. In this study, a composite plate having four zones coated with piezoelectric paint was used for impact monitoring test. The sensitivity of the piezoelectric paint sensor was obtained by measuring the output voltages against the impact force. In addition to the sensitivity measurement, the impact position has been also estimated by comparing the output signals of the paint sensors when the impact occurs on the specimen.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.1
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• pp.49-57
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• 2002

The possibility of a transmission noise reduction of piezoelectric smart panels using piezoelectric shunt damping is experimentally studied. Piezoelectric smart panel is basically a plate structure on which piezoelectric patch with shunt circuits is mounted and sound absorbing materials are bonded on the surface of the structure. Sound absorbing materials can absorb the sound transmitted at mid frequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. To be able to reduce the sound transmission at low panel resonances, piezoelectric damping using the measured electrical impedance model is adopted. Resonant shunt circuit for piezoelectric shunt damping is composed of register and inductor in series, and they are determined by maximizing the dissipated energy throughout the circuit. The transmitted noise reduction performance of smart panels is investigated using an acoustic tunnel. The tunnel is a tube with square crosses section and a loud-speaker is mounted at one side of the tube as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across panels is measured. Noise reduction performance of a smart panels possessing absorbing material and/or air gap shows a good result at mid frequency region but little effect in the resonance frequency. By enabling the piezoelectric shunt damping, noise reduction of 10dB, 8dB is achieved at the resonance frequencise as well. Piezoelectric smart panels incorporating passive method and piezoelectric shunt damping are a promising technology for noise reduction in a broadband frequency.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.372-377
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• 2001

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model of a piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate the effective properties of fiber composites are extended to apply to the PFPMIDE model. The new model is validated comparing with available experimental data and other analytical results.