• Title, Summary, Keyword: Piezoelectric signals

Search Result 129, Processing Time 0.036 seconds

Developing two Dimensional Film Speaker using Piezoelectric Materials

  • Um, Keehong;Lee, Dong-Soo
    • International Journal of Internet, Broadcasting and Communication
    • /
    • v.4 no.1
    • /
    • pp.1-2
    • /
    • 2012
  • A speaker is a system which produces sound through electromechanical operations. It transforms electronic signals into audible sound signals. Almost all speakers are three dimensional. These days, many mobile electronic devices such as mobile electronic devices have become smaller and thinner. A problem with this miniaturization, however, is that the volume of speakers has also decreased. In contrast to conventional three dimensional speakers, we have invented a new type of two dimensional flexible speaker by utilizing the reverse piezoelectric effect.

Evaluation on the Driving Characteristics of a Precise Actuator Using Piezoelectric Elements (압전소자를 이용한 정밀 액츄에이터의 구동특성 평가)

  • Kim, S.C.;Kim, S.H.;Kwak, Y.K.
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.12 no.12
    • /
    • pp.45-52
    • /
    • 1995
  • A prototype of a linear piezoelectric actuator is developed and its dynamic behaviors are investigated. The actuator consists of a driving tip with two stacked piezoelectric elements and a slider. Dynamic characteristics of slider over various vibration lici of the driving tip and changes of normal force acting on the vibratory tip are examined through experiments. The moving direction of slider can be controlled by changing a phase angle between input signals applied to piezoelectric elements. A change of phase difference between input signals also have a great influence on the vibration locus of driving tip. Changes of slider motion due to different vibration loci are examined by experiments.

  • PDF

Impact Signal Monitoring of a Composite Structure Using Piezoelectric Paint Sensor (압전 페인트 센서를 이용한 복합재 구조물의 충격 신호 감지)

  • Park, Seung-Bok;Han, Dae-Hyun;Kang, Lae-Hyong
    • Composites Research
    • /
    • v.27 no.4
    • /
    • pp.141-145
    • /
    • 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.

Flexible Piezoelectric Nanocomposite Generator Devices based on BaTiO3 Dendrite Nanostructure (티탄산바륨 덴드라이트 나노구조체 기반 플렉서블 압전 나노발전소자)

  • Bae, Soo Bin
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.18 no.2
    • /
    • pp.139-145
    • /
    • 2015
  • In this paper, the flexible piezoelectric nanocomposite generator(NCG) device based on $BaTiO_3$ nanostructures was fabricated via simple and low-cost spin coating method. The $BaTiO_3$ nanostructures synthesized by self-assembly reaction showed dendrite morphologies. To produce the piezoelectric nanocomposite(p-NC layer) which acts as an electric energy source in NCG device, the piezoelectric nanopowders($BaTiO_3$) were dispersed in polydimethylsiloxane(PDMS). Sequently, the p-NC layer was inserted in two dielectric layer of PDMS; these layers enabled the NCG device flexibility as well as durability prohibiting detachment(exfoliation) for significantly mechanical bending motions. The fabricated NCG device shows average maximum open circuit voltage of 6.2 V and average maximum current signals of 300 nA at 20 wt% composition of $BaTiO_3$ nanostructures in p-NC layer. Finally, the flexible energy harvester generates stable output signals at any rate of frequency which were used to operate LCD device without any external energy supply.

Piezoelectric impedance based damage detection in truss bridges based on time frequency ARMA model

  • Fan, Xingyu;Li, Jun;Hao, Hong
    • Smart Structures and Systems
    • /
    • v.18 no.3
    • /
    • pp.501-523
    • /
    • 2016
  • Electromechanical impedance (EMI) based structural health monitoring is performed by measuring the variation in the impedance due to the structural local damage. The impedance signals are acquired from the piezoelectric patches that are bonded on the structural surface. The impedance variation, which is directly related to the mechanical properties of the structure, indicates the presence of local structural damage. Two traditional EMI-based damage detection methods are based on calculating the difference between the measured impedance signals in the frequency domain from the baseline and the current structures. In this paper, a new structural damage detection approach by analyzing the time domain impedance responses is proposed. The measured time domain responses from the piezoelectric transducers will be used for analysis. With the use of the Time Frequency Autoregressive Moving Average (TFARMA) model, a damage index based on Singular Value Decomposition (SVD) is defined to identify the existence of the structural local damage. Experimental studies on a space steel truss bridge model in the laboratory are conducted to verify the proposed approach. Four piezoelectric transducers are attached at different locations and excited by a sweep-frequency signal. The impedance responses at different locations are analyzed with TFARMA model to investigate the effectiveness and performance of the proposed approach. The results demonstrate that the proposed approach is very sensitive and robust in detecting the bolt damage in the gusset plates of steel truss bridges.

Sensing properties of optical fiber sensor to ultrasonic guided waves

  • Zhou, Wensong;Li, Hui;Dong, Yongkang;Wang, Anbang
    • Smart Structures and Systems
    • /
    • v.18 no.3
    • /
    • pp.471-484
    • /
    • 2016
  • Optical fiber sensors have been proven that they have the potential to detect high-frequency ultrasonic signals, in structural health monitoring field which generally refers to acoustic emission signals from active structural damages and guided waves excited by ultrasonic actuators and propagating in waveguide. In this work, the sensing properties of optical fiber sensors based on Mach-Zehnder interferometer were investigated in the metal plate. Analytical formulas were conducted first to explore the parameters affecting its sensing performances. Due to the simple and definable frequency component, the Lamb wave excited by the piezoelectric wafer was employed to study the sensitivity of the proposed optical fiber sensors with respect to the frequency, rather than the acoustic emission signals. In the experiments, according to above investigations, spiral shape optical fiber sensors with different size were selected to increase their sensitivity. Lamb waves were excited by a circular piezoelectric wafer, while another piezoelectric wafer was used to compare their voltage responses. Furthermore, by changing the excitation frequency, the tuning frequency characteristic of the proposed optical fiber sensor was also investigated experimentally.

Delamination Detection at a Bolt Hole Using a Built-in Piezoelectric Active Sensor Array (배열 압전 능동 센서를 이용한 볼트 구멍의 층간분리 탐지)

  • Park, Chan-Yik;Kim, Min-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.36 no.6
    • /
    • pp.550-557
    • /
    • 2008
  • Delamination damage at a bolt hole in a composite stiffened panel was detected using a built-in piezoelectric active sensor array. Various signal processing techniques were used to detect an invisible small scale delamination around a fastener hole due to localized transverse loading. A built-in piezoelectric sensor array was used to generate diagnostic signals and to measure response signals. Then, the response signals were processed to extract damage-sensitive features. Damage indexes were calculated to estimate the severity and location of the damage from the features.

Low Velocity Impact Monitoring for a Composite Sandwich Beam Using Piezo Thin Film Sensors (압전필름센서를 이용한 복합재 샌드위치 보의 저속충격 모니터링)

  • Park, Chan Ik;Lee, Gwan Ho;Kim, In Geol;Lee, Yeong Sin
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.31 no.2
    • /
    • pp.51-56
    • /
    • 2003
  • The piezoelectric thin film(PVDF: polyvinylidene fluoride) sensors having good dynamic sensing charachteristics can be used to monitor low vwlocit impact on composite structures. The impact response function for composite sandwich beam was derved. The impact tests at low energy without inducing damage were performed on the instrumented drop weight impact tester. The measured signals of PVDF sensors attached on the surface of the beam agreed well with the simulated signals. And the inverse technique was applied to reconstruct the impact forces from the PVDF sensor signals. Most of reconstructed impact forces showed good agreement with the measured forces. The comparison results showed that the piezoelectric thin film sensor can be used to monitor the low velocity impact on composite sandwich structures.

A Comparison Study of Output Performance of Organic-Inorganic Piezoelectric Nanocomposite Made of Piezoelectric/Non-piezoelectric Polymers and BaTiO3 Nanoparticles (압전 및 비압전 폴리머와 BaTiO3 나노입자로 제조된 유-무기 압전 나노복합체의 발전성능 비교연구)

  • Hyeon, Dong Yeol;Park, Kwi-Il
    • Journal of Korean Powder Metallurgy Institute
    • /
    • v.26 no.2
    • /
    • pp.119-125
    • /
    • 2019
  • Piezoelectric energy harvesting technology is attracting attention, as it can be used to convert more accessible mechanical energy resources to periodic electricity. Recent developments in the field of piezoelectric energy harvesters (PEHs) are associated with nanocomposites made from inorganic piezoelectric nanomaterials and organic elastomers. Here, we used the $BaTiO_3$ nanoparticles and piezoelectric poly(vinylidene fluoride) (PVDF) polymeric matrix to fabricate the nanocomposites-based PEH to improve the output performance of PEHs. The piezoelectric nanocomposite is produced by dispersing the inorganic piezo-ceramic nanoparticles inside an organic piezo-polymer and subsequently spin-coat it onto a metal plate. The fabricated organic-inorganic piezoelectric nanocomposite-based PEH harvested the output voltage of ~1.5 V and current signals of ~90 nA under repeated mechanical pushings: these values are compared to those of energy devices made from non-piezoelectric polydimethylsiloxane (PDMS) elastomers and supported by a multiphysics simulation software.

Investigation on PVDE & PZT Sensor Signals for the Low-Velocity Impact Damage of Gr/Ep Composite Laminates (복합적층판의 저속충격손상에 따른 PZT 센서와 PVDF 센서의 신호 분석)

  • 이홍영;김진원;최정민;김인걸
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • /
    • pp.125-128
    • /
    • 2003
  • Low-velocity impact damage is a major concern in the design of structures made of composite materials, because impact damage is hidden inside and cannot be detected by visual inspection. The piezoelectric thin film sensor can be used to detect variations in structural and material properties for structural health monitoring. In this paper, the PVDF and PZT sensors were used for monitoring impact damage initiation in Gr/Ep composite panel to illustrate this potential benefit. A series of impact test at various impact energy by changing impact mass and height is performed on the instrumented drop weight impact tester. The wavelet transform(WT) is used to decompose the piezoelectric sensor signals in this study. Test results show that the particular waveform of sensor signals implying the damage initiation and development are detected above the damage initiation impact energy. And it is found that both PZT and PVDF sensors can be used to detect the impact damage.

  • PDF