Metal Core Piezoelectric Fiber Research Articles

Research on Impact Load Localization Based on Piezoelectric Fibers with Metal Cores

Using a metal core piezoelectric fiber (MPF) as a sensing element and utilizing its directional characteristics, a shock load localization method based on the MPF flower structure is proposed. This method does not need to know the propagation speed of stress waves in the structure. At the same time, experimental research on impact load positioning of plate structures was conducted using this method. The research results showed that the method based on MPF flower shaped composite structure can be used for impact load positioning, and the positioning accuracy is high.

Double-layer electrowetting-aided spinning for fabrication of metal-core piezoelectric-piezoresistive composite fiber

ABSTRACT Metal core piezoelectric fiber (MPF) with excellent dynamic force response performance is a promising coaxial fiber, but its application in numerous occasions requiring simultaneous detecting of static and dynamic forces is limited due to its inability to detect static forces. To overcome this problem, this paper proposes a novel double-layer electrowetting-aided spinning to produce a metal-core piezoelectric piezoresistive composite fiber (MPPCF). The MPPCF is composed of seven layers from inside to outside including a metal core, a polyimide (PI) layer, a poly(vinylidene-trifluoro-ethylene) (P(VDF-TrFE)) layer, a poly(chloro-p-xylylene) (Parylene C) layer, a middle sliver paste layer, a multi-walled carbon nanotubes (MWCNT)-polyurethane (PU) layer and an outside silver paste layer. The results show that MPPCF with good coaxial structure and surface morphology can be prepared by this technology. After testing, the MPCCF is sensitive to the dynamic force excited by vibration and the static force caused by bending.

Viscosity sensor with temperature measurement function based on multifunctional metal matrix composite

A temperature-compensated viscosity sensor was developed. The sensor consisted of a multifunctional metal matrix composite incorporating a metal-core piezoelectric fiber and a surface-oxidized metal fiber. This viscosity sensor was developed as a sensor that can withstand harsh environments, such as engine oil monitoring. In this case, viscosity is affected by oil deterioration, sludge mixing, and temperature changes. Therefore, a multifunctional metal matrix composite was fabricated using two metal-core piezoelectric fibers for viscosity measurements, and a surface-oxidized metal fiber for temperature. The metal oxide surface has a notch made by removing the oxide film, which forms a thermocouple when it comes into contact with the metal matrix. After evaluating the device's characteristics in standard room temperature, the viscosity was measured using glycerine solutions with different concentrations and varying temperatures. The temperature dependence of the sensor was measured and used for calibrating the results. This temperature dependence was present due to changes in dimensions due to thermal expansion of the matrix, and Young's modulus, piezoelectric constant, and relative dielectric constant of the piezoelectric ceramic fibers. A correction formula was calculated based on temperature dependence to demonstrate that temperature compensation was possible at range of from 2 to 25 Pa s kgm3.

A biomimetic vibration sensor using a symmetric electrodes metal core piezoelectric fiber

A biomimetic vibration sensor to sense external vibrations was designed based on the hair receptor of insects similar to the water strider. Platinum core piezoelectric ceramic fiber body was prepared by squeeze and press method. This was followed by high-temperature sintering, surface electrode coating, and polarizing to fabricate the symmetric coated metal core piezoelectric fiber vibration sensor. A cantilever beam structure with two surface electrodes was designed as the theoretical sensor model. The fiber was fixed on a matrix structure. Experiments were performed to verify sensing characteristics under impact vibration and simple harmonic excitation. Results showed that the symmetric coated metal core piezoelectric fiber was able to sense amplitude and direction of impact vibration along with frequency, amplitude, and direction under simple harmonic excitation. Such a biomimetic vibration sensor can be effectively used to sense vibration amplitude and direction for a wide range of applications.

Development of novel symmetrical electrode metal-core piezoelectric fibers for an application as airflow sensors

Development of novel symmetrical electrode metal-core piezoelectric fibers for an application as airflow sensors

Damage detection based on sparse virtual element boundary measurement using metal-core piezoelectric fiber

Pseudo-excitation approach is a recently developed vibration-based damage detection method, exhibiting some appealing features for structural health monitoring applications. However, two main bottlenecking problems, that is, dense measurement points and venerable noise immunity, hamper its use in practical applications. This article tackles these problems by proposing a novel method based on sparse virtual element boundary measurement using metal-core piezoelectric fiber sensors. Different from the local “point-by-point” interrogation modality used in the original pseudo-excitation approach, the proposed method divides the entire structure into several virtual elements to construct a damage location index, describing the damage-induced dynamic perturbation in the corresponding virtual element. To avoid the high-order derivative calculation, which is mainly responsible to the low noise robustness of the original pseudo-excitation approach, metal-core piezoelectric fiber sensors are used to directly measure the surface strains, but only at the virtual element boundaries, leading to a significantly reduced number of measurement points. Experiment is designed and carried out using a cantilever beam, in which a 10-metal-core piezoelectric fiber sensor array is embedded in the structure. Along with the sparse laser Doppler vibrometer measurement, a normalized damage location index is constructed. Results demonstrate that the proposed method not only enhances the noise robustness but also allows a significant reduction in the number of measurement points.

Design and Fabrication of a Multi-electrode Metal-core Piezoelectric Fiber and Its Application as an Airflow Sensor

Crickets, similar to some other insects, have highly sensitive filiform hairs on their cerci that can detect miniscule changes in airflow. This study imitates the perception mechanism of these filiform sensory hairs of crickets by designing and fabricating a Multi-electrode Metal Core Piezoelectric Fiber (MMPF)-based airflow sensor. Four longitudinal conductive sheets were coated symmetrically on their surfaces with Metal-core Piezoceramic Fibers (MPF). The four fan-shaped piezoelectric ceramics with surface electrode covers were polarized. After successful polarization, the cantilevered MMPF could be used as an airflow sensor. The four electrodes on the surface were symmetrically divided into two groups. Therefore, two signals can be produced by a single fiber sensor. The theoretical model of an MMPF airflow sensor has been established. The model indicates that the ratio of the two signals is equivalent to the tangent of the airflow angle. Furthermore, the sum of the squares of the two signals is not dependent on the angle, but reflects the velocity of the airflow. Therefore, a single MMPF can be used to measure both the direction and amplitude for a given airflow. The theoretical model has been confirmed via experimental measurements.

Fabrication of a polyvinylidene difluoride fiber with a metal core and its application as directional air flow sensor

We fabricated a sensitive air flow detector that mimic the sensing mechanism found at the tail of some insects. [see Y. Yang, A. Klein, H. Bleckmann and C. Liu, Appl. Phys. Lett. 99(2) (2011); J. J. Heys, T. Gedeon, B. C. Knott and Y. Kim, J. Biomech. 41(5), 977 (2008); J. Tao and X. Yu, Smart Mat. Struct. 21(11) (2012)]. Our bionic airflow sensor uses a polyvinylidene difluoride (PVDF) microfiber with a molybdenum core which we produced with the hot extrusion tensile method. The surface of the fiber is partially coated with conductive silver adhesive that serve as surface electrodes. A third electrode, the metal core is used to polarize polyvinylidene difluoride (PVDF) under the surface electrodes. The cantilever beam structure of the prepared symmetric electrodes of metal core piezoelectric fiber (SMPF) is used as the artificial hair airflow sensor. The surface electrodes are used to measure output voltage. Our theoretical and experimental results show that the SMPF responds fast to air flow changes, the output charge has an exponential correlation with airflow velocity and a cosine relation with the direction of airflow. Our bionic airflow sensor with directional sensing ability can also measure air flow amplitude. [see H. Droogendijk, R. G. P. Sanders and G. J. M. Krijnen, New J. Phys. 15 (2013)]. By using two surface electrodes, our sensing circuit further improves sensitivity.

J0440102 昇面層形成・接合法によリアルミニウムに埋込まれた金属コア圧電ファイバの結晶方位解析

In this study, crystal orientation analysis of metal-core piezoelectric fiber that embedded in aluminum matrix was investigated. Piezoelectric ceramics are widely used due to their piezoelectric effect as excellent transducers. In other hands, there is a problem that the piezoelectric ceramics very brittle. In order to solve this problem, it was successful that embedding a metal-core piezoelectric ceramics fiber in an aluminum matrix without fracture by using the Interphase Forming/Bonding method that proposed by Asanuma. While this process, compression residual stress is applied to the metal-core piezoelectric ceramics fiber due to difference of coefficients of thermal expansion between the fiber and the matrix. The purpose of this study is evaluation of the polarization of the fiber under the residual stress by EBSD (Electron Back Scatter Diffraction patterns) analysis. According to the results, orientation of (001) that is axis of the polarization into poling direction was disturbed by the residual stress. This means that movement of off-center ion in perovskite structure was obstructed by the residual stress.

Detection of Impact Location by Using Anisotropy of Output Voltage of Metal-Core Piezoelectric Fiber/Aluminum Composites

This paper describes the detection of an impact location by using anisotropy of the output voltage of a metal-core piezoelectric ceramic fiber/aluminum composite. Metal-core piezoelectric ceramic fibers are very fragile. The mechanical properties of metal-core piezoelectric ceramic fibers can be improved by embedding the fibers into the metals that have excellent reliability and strength. Therefore, metal-core piezoelectric ceramic fiber/aluminum composites were developed by using the Interphase Forming/Bonding method. Furthermore, the output voltage characteristics of fabricated a composite were evaluated, and the anisotropy of the output voltage was observed. In this study, the impact location detection system was developed by using the anisotropy of the output voltage of the composite. It is expected to reduce the number of sensors compared with conventional systems while maintaining the accuracy. As a result, the impact location detection was successfully developed by using the model of the output voltage of the composites that were disposed in two different positions to obtain the signals.

Micromechanics modeling of electro-viscoelastic–plastic response of metal core piezoelectric fiber polymer composites

A micromechanics model was developed to predict the effective time-dependent and non-linear multiphysics responses of metal core piezoelectric fiber reinforced polymer matrix composites. The present model is established on the basis of variational asymptotic method and implemented using finite element method. In light of the time-dependent and non-linear characteristics of composites, an incremental procedure in conjunction with an instantaneous electromechanical matrix of composites was established. The proposed model can be readily used to simulate the effects of multiphysics loadings on the behavior of metal core piezoelectric fiber reinforced polymer matrix composites.

An imaging method for impact localization using metal-core piezoelectric fiber rosettes

As a novel piezoelectric device, metal-core piezoelectric fiber has great potential to be a structurally integrated transducer for guided-wave structural health monitoring. Compared with common piezoelectric ceramics with in-plane isotropic characteristic, metal-core piezoelectric fiber exhibits unique directivity in Lamb wave sensing which can locate the direction of the impact without any information about time of flight or speed of propagation. This article introduces a metal-core piezoelectric fiber rosette that contains three metal-core piezoelectric fibers with an angle of 120° between adjacent metal-core piezoelectric fibers. To simplify the process of placing three metal-core piezoelectric fibers onto the structure and improve the performance of metal-core piezoelectric fiber rosettes, a method for packaging metal-core piezoelectric fiber rosette is presented. By coupling the piezoelectric effect to the wave strain field, the directivity of metal-core piezoelectric fiber is derived. In order to determine the direction of an incoming wave, previous work measures the amplitudes of metal-core piezoelectric fibers and calculates the wave direction by the rosette principles. However, the calculated wave direction is very sensitive to the measurement error, which comes from unavoidable sensor noise and complex dispersive effect in actual application. To improve the accuracy, a new method that combines an imaging method with the rosette approach is proposed. Its accuracy is validated by experiments, and the phenomena in experiments are also discussed.

Fabrication and Characterization of Piezoelectric Ceramic Fiber/Aluminum Alloy Composites

This paper describes the fabrication and characterization of a piezoelectric ceramic fiber/aluminum alloy composite using the Interphase Forming/Bonding (IF/B) method. A metal-core piezoelectric ceramic fiber is very fragile and reacts with molten aluminum; therefore, general fabrication processes such as diffusion bonding and casting are difficult to apply. In this study, hot pressing conditions were examined in order to embed a metal-core piezoelectric ceramic fiber, without mechanical damage and loss of piezoelectricity, in an aluminum alloy matrix instead of the pure aluminum matrix used in previous studies. As the results, the proper hot pressing conditions, that is, pressure and temperature of 2.2 MPa and 873 K, respectively, enable the removal of the coarse and fragile eutectic alloy phase from the composite. In addition, the output voltage characteristics of the piezoelectric ceramic fiber/aluminum composite were evaluated by impact testing. The results show that the output voltage generated from the composite is proportional to the square root of impact energy.

J0450303 金属コア圧電ファイバ/アルミニウム複合材料の出力電圧異方性を利用した衝撃検知の検討([J045-03]知的材料・構造システム(3),機械材料・材料加工部門)

This paper describes development of an impact detection system by using the anisotropy of output voltage of metal-core piezoelectric fiber/aluminum composite. A metal-core piezoelectric ceramic fiber is very fragile and reactive with molten aluminum. Therefore general fabrication processes such as dimision bonding and casting are hard to be applied. However, embedding the metal-core piezoelectric fiber into an aluminum matrix was succeeded by using IF/B method. Furthermore, output voltage characteristics of fabricated composite were evaluated, and anisotropy of the output voltage was observed. In this study, impact location and energy detection system was developed by using anisotropy of output voltage of the composite. It is expected to reduce the number of sensors compared to conventional systems and keep accuracy by using this anisotropy. As the results, the impact energy and impact location detection was successfully by using the model of the output voltage of the composites and signals that were obtained from composites disposed in two different positions. In addition, the error of impact location was 8.88 mm at the maximum, and this result is caused by the anisotropy of output voltage of metal-core piezoelectric fiber/aluminum composite.

Origin of the low piezoelectric coefficient of metal core 0.3Pb(Zn1/3Nb2/3)O3–0.7Pb(Zr,Ti)O3 piezoelectric fibers

The piezoelectric properties of 0.3Pb(Zn1/3Nb2/3)O3–0.7Pb(Zr,Ti)O3 metal-core piezoelectric fibers (0.3PZN–0.7PZT MPFs) (k31=0.253, d31=−120pC/N) are lower than those of bulk ceramic counterpart (k31=0.375, d31=−195pC/N). In order to investigate the origin of this discrepancy, geometrical shape effect and polarization were studied. The effect of geometrical shape is a main cause of the decreased piezoelectric properties of the MPF. However, even though the effect of geometrical shape being considered, the piezoelectric properties of the MPF are much lower than expected. After considering the polarization effect, there is excellent agreement between the expected and experimental measurements. The effect of geometrical shape and polarization are the cause of the decreased properties of the MPFs.

J045074 圧電ファイバ/アルミニウム合金複合材料の創製([J045-07]知的材料・構造システム(7))

This paper describes fabrication of a piezoelectric ceramic fiber/aluminum alloy composite using the Interphase Forming/Bonding(IF/B) method. A metal-core piezoelectric ceramic fiber is very fragile and reactive with molten aluminum, therefore general fabrication processes such as diffusion bonding and casting are hard to be applied. In this study, hot pressing condition was examined in order to embed the metal-core piezoelectric ceramic fiber without mechanical damage and loosing piezoelectricity to an aluminum alloy matrix instead of the pure aluminum matrix used in the previous studies. As the results, the proper hot pressing conditions such as temperature, pressure and period have been determined, and the piezoelectricity of the embedded fiber was confirmed by the measurement of P-E hysteresis loop. The proper hot pressing condition, that is, pressure and temperature are 2.2 MPa and 873 K, respectively enables to remove the coarse and fragile eutectic alloy phase from the composite.

Temperature stability and fabrication of Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 fibers with Pt core

In order to improve the electrical properties of metal-core piezoelectric ceramic fibers at high temperature, Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 piezoelectric ceramics with high Curie temperature were selected. The Pb(Zn1/3Nb2/3) O3–Pb(Zr,Ti)O3 metal-core piezoelectric ceramic fibers were successfully fabricated by extrusion Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 powder around a platinum wire. The microstructure and electrical properties of Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 ceramics with different calcining and sintering temperatures were investigated. Compared with the previous metal-core piezoelectric ceramic fibers, the Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 fibers showed lower piezoelectric and dielectric properties ([Formula: see text], k31 = 0.253, and d31 = −120 pC N−1). However, the Curie temperature of Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 ceramics is about 295°C, much higher than that of 0.55Pb(Ni1/3Nb2/3)O3–0.45Pb(Zr0.3Ti0.7)O3 ceramics (110°C). The Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 fibers can be used at the highest temperature of 150°C, and the temperature stability of Pb(Zn1/3Nb2/3)O3–Pb(Zr,Ti)O3 fibers is much better than that of 0.55Pb(Ni1/3Nb2/3)O3–0.45Pb(Zr0.3Ti0.7)O3 fibers.

213 金属基圧電複合材料の各種応用のための特性評価

This paper describes output voltage characteristic and output power characteristic of the metal-core piezoelectric ceramic fiber/aluminum composite. As the metal-core piezoelectric fiber is very fragile, the interphase forming/bonding (IF/B) method proposed by Asanuma was used for embedding it in an aluminum matrix without fracturing it. In this study, thin patch type devices developed by using the IF/B method were evaluated with the oscillation test equipment. As the results, 1) the output voltages from the device were found to be proportional to their strains, 2) the output power generated by the specimen increases with increasing the square of its strain.

Metal core piezoelectric ceramic fiber rosettes for acousto-ultrasonic source localization in plate structures

This paper presents an approach for acousto-ultrasonic source (passive damage or impact) localization based on metal core piezoelectric fiber (MPF) rosettes. MPF is a new ty pe piezoelectric ceramic device with small size and has high directivity to sense Lamb waves. The response of surface-bonded MPF sensors to Lamb-wave fields is explored theoretical ly and experimentally. The good directional properties of MPF are used to determine the direction of propagation of the acoustic waves by mounting three MPF sensors in a rosette configuratio n. Two suitably spaced rosettes are used to locate the source of the ultrasound by taking the intersection of the directio n given by each rosette. The performance of the rosettes for source location is validated on an aluminum plate.

RESPONSE OF METAL CORE PIEZOELECTRIC FIBERS TO UNSTEADY AIRFLOWS

In the previous study, possible applications of metal core piezoelectric fibers with a diameter of 200 to 250 µm as bionic airflow sensors mimicking the flow sensitive receptor hairs of crickets have been proposed. This study aims to investigate the dynamic responses of the metal core piezoelectric fibers to unsteady airflow. The metal core piezoelectric fiber is half coated on the outer surface and is used in the bending mode. Wind tunnel tests were carried out and the output voltage of the fiber under the excitation of the unsteady aerodynamic force during flow acceleration and deceleration was measured when the wind tunnel was suddenly closed or opened by a shutter. The relationship between the maximum voltage and the steady-state velocity and that between the voltage and the acceleration of flow were also obtained.