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Compared with piezoelectric ceramics such as lead zirconate titanate (PZT) ceramics, the low density and high compliance of the PVDF films make them a more suitable choice in modal testing, especially for detecting high-frequency modes in flexible or inflatable structures. In this work, dynamic sensing performances of PVDF films for flexible struct...
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... that the first 26 resonant frequencies are all clearly indicated in . To see how the impact locations and sensing loca- tions affect the responses of the PVdF film and the re- sults of modal testing for resonant frequencies, some of the mode shapes of the cantilever plate (i.e., symmetric modes 7 to 12) provided by FEM computations are shown in Fig. 5. In Fig. 5, the contour lines and the bold lines depict the displacements and the nodal lines of the cantilever plate, respectively. compared with the mode shapes, we can see that mode s9 in the spectrum shown in Fig. 4(b) is hardly detected because the sensing location (P1) is on the nodal line of mode s9 (similar to modes s10 and ...
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... that the first 26 resonant frequencies are all clearly indicated in . To see how the impact locations and sensing loca- tions affect the responses of the PVdF film and the re- sults of modal testing for resonant frequencies, some of the mode shapes of the cantilever plate (i.e., symmetric modes 7 to 12) provided by FEM computations are shown in Fig. 5. In Fig. 5, the contour lines and the bold lines depict the displacements and the nodal lines of the cantilever plate, respectively. compared with the mode shapes, we can see that mode s9 in the spectrum shown in Fig. 4(b) is hardly detected because the sensing location (P1) is on the nodal line of mode s9 (similar to modes s10 and s11). ...
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... sensing locations, comparing Figs. 6(a) and 6(b) (i.e., impact at l2) with Figs. 4(a) to 4(c) (i.e., impact at l1), we can see , results at location P2), we can see that sym- metric mode s11 are both hardly detected from the two sensing locations. although the two sensing locations (i.e., P1 and P2) are not on the nodal lines of s11 (as shown in Fig. 5), from the mode shapes of s11, we can see that it results from the fact that the impact location l2 is very close to the nodal line. as for antisymmetric modes, there are 9 antisymmetric modes [i.e., a2, a4, a5, a6, a8, a9, a11, a13, and a23 shown in Figs. 6(a) and 6(b)] detected in the transient responses obtained at sensing location ...
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Citations
... Kapuria et al. [21] used a laser optical displacement sensor to measure the static load-deflection and dynamic response behavior of FGM beams with simply supported and cantilever boundary conditions. In another research, Chuang et al. [22] experimentally investigated transient responses and frequency spectra of thin and thick plates with different boundary conditions by using polyvinylidene fluoride (PVDF) films as sensing devices. Although many publications have used the Mindlin plate theory to analyze the flexural type vibration, most of them considered isotropic material structures. ...
... Tables 3, 4 flexural type vibration (from mode 1 to mode 75) obtained theoretically by modified FSDT and experimentally from strain gauges (i.e., at sensing locations S1 and S2). Chuang et al. [22] also utilized the same experimental setup to demonstrate the performances of the PVDF sensor in detecting the dynamic behavior for a thick plate specimen. In Tables 3, 4 and S2) and different impact locations (e.g., H1 and H2), and all the discrepancy with FEM is smaller than 1.38%. ...
The theoretical analysis of thick plate vibration behavior has been investigated in the literature, but most of the studies were focused on flexural dynamic characteristics and lack experimental verification. In this study, the analytical solutions based on the superposition method for both the flexural and extensional vibrations are presented to obtain resonant frequencies and associated mode shapes for a transversely isotropic thick rectangular plate. The displacement equilibrium equations and boundary conditions of the modified first-order shear deformation theory (FSDT) are derived by utilizing Hamilton’s principle and the variation method. To verify the validity of the theoretical model, the finite-element method (FEM) and impact experiment results for thick plates are employed in this work. Excellent agreement of resonant frequencies and associated mode shapes is obtained for FEM calculation and theoretical analysis. To excite vibrations of a thick rectangular plate, a steel ball controlled by an electromagnet is utilized. A steel ball is dropped freely from a height of 231 mm on the top of the plate surface, and a transient wave will be generated after the ball impact on the specimen. The frequency spectrum of the thick rectangular plate is constructed by using the fast Fourier transform of the time-domain transient response. The excited resonant frequencies obtained from experimental measurement are compared with theoretical results. The comparisons show that the modified FSDT provides an excellent prediction of the resonant frequencies and mode shapes for the dynamic characteristics of thick rectangular plates.
... Excitation of vibrations and measurement of the signal must be implemented using actuators and special measurement devices (sensors). The capabilities of using piezoelements for registration of high frequency vibrations are described in [11]. The Authors of this research capture vibrations of the plate up to 40 kHz with the help of a piezoelectric sensor which proves the possibility of using such devices for measuring high frequency vibrations. ...
The purpose of this work is to study three different models of delamination in composite plate (the free mode model, the constrained model and the contact model) and applicability of this models to the vibrational method of damage detection based on frequency shifts. The results of numerical simulation have shown that the free mode model leads to abrupt changes in natural frequencies due to non-physical condition of mutual penetration of adjacent volumes in the defect zone. The constrained and the contact models yield qualitative agreement in shifts of natural frequencies with a change of the defect size. All models have shown the necessity of analyzing shifts of high frequencies to detect small size delamination. Citation: Serovaev, G.S., Matveenko, V. P., Numerical study of the response of dynamic parameters to defects in composite structures, Frattura ed Integrità Strutturale, 38 (2016) 392-398.
... The in plane piezoelectric charge constant (d 31 ) for EAPap has been measured in the range of 8-28.2 pC/N [Kim et al., 2008c], which can increase when the wet drawing method is applied or by using an electrically aligned cellulose film Yun et al., 2009]. PVDF is a prominent piezoelectric polymer, and it has the ability to measure dynamic strain, and obtaining good results for high-frequency vibration modes of structures [Chuang et al., 2012[Chuang et al., , 2014. PVDF has also been characterized for use in pressure sensors, ultrasonic sensors, and for monitoring cardiorespiratory signals [Shirinov and Schomburg, 2008;Rathod et al., 2010]. ...
We characterized a vibration sensor made of piezoelectric paper by measuring the frequency response function of an aluminum cantilever that was subjected to impulse loading and random excitation. The dynamic characteristics of the device were measured by recording the transient response of the smart cantilever beam with a pair of electro-active paper (EAPap) and polyvinylidene fluoride (PVDF) sensors located at a 5 mm distance from the clamped end as well as from a second pair of piezoelectric sensors located at a distance of 140 mm. The responses were measured by impacting the cantilever at its tip and at its mid-point. A fast Fourier transform was applied on the time domain data to measure the resonant frequencies of the vibrating structure. Both the EAPap and the PVDF sensors were observed to be very sensitive to varying levels of dynamic strain. The EAPap sensor showed a low strain sensitivity that was found to be desirable due to the inherent piezoelectricity and eco-friendly behavior of the material. The results revealed that the dynamic sensing ability of the EAPap at a low frequency range was quite comparable to that of PVDF when monitoring structural vibrations. The frequency response function was also measured via random excitation, piezoelectricity of the EAPap sensor shows potential for sensing vibrations with a dynamic response.
Recently, ultrahigh-frequency (UHF) ultrasonic transducers (> 100 MHz) have been widely applied in research fields such as medical diagnostics, nondestructive testing, energy harvesting, and so on, due to their capability of creating high-resolution ultrasonic images and detecting micro-scale defects. To accomplish this, in this study, ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (i.e., PIN-PMN-PT) polycrystalline single-phase thin film was fabricated for UHF ultrasonic transducers due to their extraordinary piezoelectric properties and electromechanical coupling coefficients. A tri-layered structure (of 1) aluminum substrate, 2) the PIN-PMN-PT thin film, and 3) a silver electrode) was used to create a PIN-PMN-PT thin film compatible with intense thermal treatment and having low cost. To analyze the performance of the newly developed PIN-PMN-PT thin film, data were collected on its crystallographic and piezoelectric characteristics, fabrication process, analysis of piezoelectric constants, and ultrasonic pulse-echo response waveforms according to different design conditions (various front matching layers, backing materials, and media). These data were provided by X-ray diffraction, X-ray fluorescence, X-ray reflectometry, field emission scanning electron microscopy, and polarization-electric field hysteresis curves. Moreover, pulse-echo simulation was conducted using PiezoCAD software based on the Krimholtz-Leedom-Matthaei model. The results showed that the proposed PIN-PMN-PT thin film exhibited ultrahigh-resonance frequencies of ~ 500 MHz. Ultimately, it was concluded that the new high-frequency PIN-PMN-PT thin film could be applied in a variety of fields because its performance has been verified.
This paper reports the result of an investigation into the nonlinear viscoelastic dynamic characteristics of bi-graphene sheets/piezoelectric (BGP) laminated films subjected to moving particles (gas molecules, lithium ion, catalyst molecules, etc.). Based on the nonlocal elasticity theory and the von Kármán nonlinear geometric relation, and considering a rigorous van der Waals force between any two layers and the viscoelastic behavior of piezoelectric, the nonlinear viscoelastic dynamic equations of BGP laminated films is found by utilizing Hamilton's principles and Galerkin method. A reformulated differential quadrature method (DQM) is used to solve the nonlinear viscoelastic dynamic equation. Results show that the applied voltage and the mass of moving particles appear in larger effect on the nonlinear dynamic characteristics of BGP laminated films; the viscoelastic behavior of piezoelectric layer decreases the nonlinear dynamic amplitude of BGP laminated films only in free vibration part; the difference between linear and nonlinear solutions depends on the speed of moving particles. The obtained new features and interesting results about the nonlinear viscoelastic dynamic responses of bi-graphene/piezoelectric laminated films under moving particles in this paper are helpful for the design of chemical, physical and biomechanical sensors for the possible applications in sensing mass, force and charge, in which graphene/piezoelectric films act as basic elements, and will trigger a wave of research on the graphene/piezoelectric films based electrical elements or devises in the near future.
Information about vibrating objects can be obtained by vibration measurements. Piezoelectric sensors made by piezoelectric ceramics, quartz, or organic piezoelectric materials, e. g. polyvinylidene fluoride (PVDF) have been adopted by many researchers to measure vibrations. Among these piezoelectric materials, PVDF has attracted much attention for its excellent properties such as outstanding chemical resistance, high thermal stability, low permitivities, low acoustic impedances, flexibility and membrane forming properties. In this paper, PVDF is introduced in brief. In addition, this paper briefly reviews the use of PVDF films as sensors for vibration measurement in the areas of portable medical detections, structural health monitoring, mechanical equipment vibration measurements and other applications. Meanwhile, some cases which have good low-frequency performances or novel features in structures will be especially introduced to provide helpful experiences for future applications. In the end, a spiral-shaped PVDF cantilever and a double-clamped PVDF beam of two piezoelectric energy harvesters are mentioned to provide ideas for reducing the resonant frequencies and enhancing the output signals of PVDF vibration sensors respectively. The idea of how to enhance the output signals of PVDF sensors for low frequency vibration measurements may be helpful to the development of geophone.
New approach for preparation of active plasmonic component with capability to switch on/off localized surface plasmon resonance (LSPR) by piezoelectric effect is described. Polyvinylidenefluoride (PVDF) was patterned by polarized KrF excimer laser beam. The polarization was perpendicular to polymer orientation introduced during poling procedure. Consequently the silver nanoclusters were sputtered onto polymer surface. Application of an external electric field leads to polymer stretching and surface smoothening. Simultaneously, silver clusters are elongated and interconnected, this process leads to dramatic decrease of surface resistance and complete quenching of plasmon related absorption.
