Piezoelectric Composite Transducers Research Articles

Evaluation of multiple transducers implementation in a magnetoelectric vibration energy harvester

Abstract A novel magnetoelectric (ME) vibration energy harvester employing magnetostrictive and piezoelectric laminate composite transducers is presented for potentially powering wireless sensor systems. The harvester consists of two four-layered Terfenol-D/PZT laminate composite and a magnetic circuit composed by two parallel magnetic springs and two rectangular magnets. The repulsive forces are realized by a magnetic spring for more robustness. In order to realize a high power density, a multiple transducer design with a lateral configuration is proposed. The magnetic flux density and the induced displacement in the magnetostrictive layers are investigated by finite element analysis to determine the optimal relative position of the twin transducers at the static equilibrium. Furthermore, the output characteristics of the harvester are experimentally studied and compared to the case when only a single transducer is used. The experimental results show that the twin lateral converter can provide a higher power outcome especially if operated at resonance. In addition, doubling the amplitude of vibration from 0.5 mm to 1 mm leads to a voltage output which is four times higher at resonance.

Estimation of the power of a MFC type piezoelectric used for electric energy recovery from vibrations

One of the possibilities of piezoelectric transducers applications are systems for electric energy recovering from mechanical vibrations. The obtained amount of electric energy is not big but sometimes it is enough for power supply some elements such us microcontrollers or other electronic devices with low energy consumptions. The main advantage of piezoelectric transducers used as power supply elements is that there is no necessary to replace batteries or use wires. In this paper results of laboratory tests of Macro Fiber Composite piezoelectric transducer that is used for electric energy recovering from mechanical vibrations are presented. The aim of the presented work was to estimate the maximum power of the MFC transducer that can be used as power supply for some electronic device. To do that a series of laboratory tests was done. The MFC transducer was glued on the cantilever beam surface. The beam’s vibrations were excited using the second one MFC transducer. The tested MFC transducer was electrically loaded with a voltage divider of various resistances. The generated electric voltage was measured and electric current was calculated to estimate the maximum power of the piezoelectric MFC transducer.

Performance comparison of 2-1-3, 1-3 and 1-3-2 piezoelectric composite transducers by finite element method

1-3 type, 1-3-2 type and 2-1-3 type piezoelectric composites are three proper smart materials for the design and manufacture of ultrasonic transducers. They have been proposed in different stages but possess similar properties. Compared with the initial 1-3 type composite, 1-3-2 composite is of higher mechanical stability. Compared with 1-3-2 composite, 2-1-3 composite has lower manufacturing difficulty. In this paper, a comparative study on these three composites in terms of receiving transducer material properties is presented. Finite element method (FEM) has been adopted to calculate longitudinal velocity, thickness electromechanical coupling coefficient and voltage receiving sensitivity. It is concluded that for a large aspect ratio $\alpha=1$, the performance of 2-1-3 composite transducer is much better than that of 1-3 and 1-3-2 composite transducers. The thickness electromechanical coupling coefficient of 2-1-3 composite transducer is about 5.58 times that of 1-3 composite transducer and 7.42 times that of 1-3-2 composite transducer. The voltage receiving sensitivity at 2 kHz of 2-1-3 composite transducer is 13.1 dB higher than that of 1-3-2 composite transducer and 12.3 dB higher than that of 1-3 composite transducer.

Novel piezoelectric composite spherical cap broadband transducer

ABSTRACTTo expand the beam-width and bandwidth of high-frequency transducer, a novel piezoelectric composite spherical cap vibrator was developed. The feasibility of expanding bandwidth was verified via finite element simulation. The vibrator was prepared by cutting the piezoelectric ceramic spherical cap and filling it with polymers. The piezoelectric composite spherical cap transducer was fabricated using the prepared vibrator. Test results show that the bandwidth of the transducer is 30 kHz and the −3 dB beam width is 40°. The novel piezoelectric composite spherical cap transducer realized the goal of high-frequency broadband wide–beam transmission.

Analysis on the three-dimensional coupled vibration of composite cylindrical piezoelectric transducers.

Three-dimensional coupled vibration of the composite cylindrical piezoelectric transducer is analyzed. The composite cylindrical piezoelectric transducer consists of an inner axially polarized piezoelectric ceramic cylinder and an outer metal cylinder with the same height. Coupled vibration of the composite cylindrical piezoelectric transducer is analyzed by equivalent elasticity method, which is an approximate analytical approach. According to this method, coupled vibration of the cylindrical transducer is regarded as an interaction between a plane radial vibration and a longitudinal vibration. The radial and longitudinal electromechanical equivalent circuits of the piezoelectric transducer are acquired. Input impedances as functions of the resonance frequency and the mechanical coupling coefficient are derived to obtain resonance frequency equations. The analytical results are supported by experimental and numerical simulated results of two prototypes of the piezoelectric transducer. The composite cylindrical piezoelectric transducer presented in this paper is superior to single cylindrical piezoelectric transducers, composite ring-type, and tube-type transducers in the field of high output power and efficiency.

Single Piezoelectric Transducer as Strain Sensor and Energy Harvester Using Time-Multiplexing Operation

This paper presents the implementation of a single piece of macro fiber composite (MFC) piezoelectric transducer as a multifunctional device for both strain sensing and energy harvesting for the first time in the context of an energy harvesting powered wireless sensing system. The multifunction device is achieved via time-multiplexing operation for alternating dynamic strain sensing and energy harvesting functions at different time slots associated with different energy levels, that is, when there is insufficient energy harvested in the energy storage for powering the system, the MFC is used as an energy harvester for charging up the storage capacitor; otherwise, the harvested energy is used for powering the system and the MFC is used as a strain sensor for measuring dynamic structural strain. A circuit is designed and implemented to manage the single piece of MFC as the multifunctional device in a time-multiplexing manner, and the operation is validated by the experimental results. The dynamic strains measured by the MFC in the implemented system match a commercial strain sensor of extensometer by 95.5 to 99.99%, and thus the studied method can be used for autonomous structural health monitoring of dynamic strain.

Transit Time Difference Flowmeter for Intravenous Flow Rate Measurement Using 1–3 Piezoelectric Composite Transducers

The flow rate of injected medication implemented by intravenous (IV) systems must be accurately monitored and meticulously controlled to prevent medical accidents. In this paper, an ultrasonic flowmeter (UF) with 1-3 piezoelectric composite transducers was designed, fabricated, and tested on a variety of flow rates of mimic medical injections. The transducer wedge for the angled beam propagation and an acoustic impedance matching layer were included in the design for transmission enhancement. To ensure an accurate measurement of flow rate, the effect of the flow distributions inside the IV tube was taken into account. The developed UF exhibited the capability of detecting low flow rates (<;0.005 m/s), with 1%-2% discrepancy compared with the reference rate of infusion.

Structural Tests of Freight Wagons on the Basis of Signals Generated By Piezoelectric Macro Fiber Composites

AbstractPaper presents a report of a research work that concerns possibilities of freight wagons modernization using new composite materials. The main aim of presented work was to verify the possibility of inference from the dynamic response of the wagon about the changes in its technical condition. During the presented works tests on real objects were carried out using Macro Fiber Composite (MFC) piezoelectric transducers glued to the freight wagon’s frame. The dynamical response of the wagon was measured while the object was driving. On the next stage the measured signal was generated on a laboratory stand using electrodynamic modal shaker and vibrations of the laboratory model were measured. Measured signals were juxtaposed on charts and analysed. The aim of this work was to verify if it is possible to detect the change in the system using measurements of vibrations that are being generated during exploitation of the freight wagon.

Equivalent force modeling of macro fiber composite actuators integrated into non-homogeneous composite plates for dynamic applications

Smart structures with integrated macro fiber composite (MFC) piezoelectric transducers have been increasingly investigated in engineering. A simple but elaborate system model of such smart structure not only can predict system dynamics, but also can reduce challenges in application. Therefore, the equivalent force (EF) modeling approach is presented to model the plate-type structures with integrated piezoelectric actuators in a semi-analytical fashion: analytical EF is applied to finite element (FE) structural models. The EF is derived from the bending effort balance between the equivalent loads, and the equivalent loads are developed by introducing the spatial distribution into a generalized Hamilton’s principle. The proposed approach is validated by cantilever aluminum beams with integrated MFC actuators and it is consistent with existing alternative approaches from literature. Then, it is validated on a non-homogeneous composite plate for dynamic applications: a laminated composite plate with integrated MFC actuators was manufactured and both an impact test and MFC drive test were elaborately carried out. The modal validation shows the high fidelity of the EF model and the predicted velocity frequency responds functions (FRFs) agree well with experimental measurement. Being applicable to both numerical and analytical modeling approaches, the EF is actually assigned to the out-plane displacement on the structure and distributed along the edges of the actuators. Therefore, it is convenient to use in EF models. The rotational degrees of freedom could also be eliminated in the EF models without losing structure complexity, since they neither link to the electromechanical coupling nor have a significant kinetic contribution to the system.

Comparison of vibration damping of standard and PDCPD housing of the electric power steering system

A comparison of two different types of electric power steering system housing is presented. The first considered type of the housing was a standard one that is made of an aluminium alloy. The second one is made of polydicyclopentadiene polymer (PDCPD) and was produced using the RIM technology. Considered elements were analysed in order to verify their properties of vibrations damping. This property is very important taking into account noise generated by elements of a car’s power steering system. During the carried out tests vibrations of analysed power steering housings were measured using Marco Fiber Composite (MFC) piezoelectric transducers. Results obtained for both considered power steering housings in case of the same parameters of vibrations excitations were measured and juxtaposed. Obtained results were analysed in order to verify if the housing made of PDCPD polymer has better properties of vibration damping than the standard one.

Study on tangentially polarized composite cylindrical piezoelectric transducer with high electro-mechanical coupling coefficient

In this work, we proposed an effective way to fabricate a tangentially polarized composite cylindrical transducer with high electro-mechanical coupling coefficient (EMCC) by radially connecting an inner tangential polarized piezoelectric tube with an outer metal ring. The resonance frequency and EMCC of the proposed transducer are calculated according to frequency equations, which are obtained from the equivalent circuit of the transducer, and the results indicate that EMCC of the tangentially polarized cylindrical transducer is much higher than that of the cylindrical transducer polarized in radial direction. Furthermore, the Finite Element Method (FEM) model of the transducer is established and used for numerical simulation of the vibration models and the optimum configuration parameters. On the basis of those theoretical results, serials of prototype transducers are manufactured with an inner tangential polarized piezoelectric tube connecting with different outer metal cylindrical shells. The admittance characteristics of the fabricated transducers measured by Impedance Analyzer clearly demonstrate that the resonance frequencies of the transducers are in good agreement with those of simulation results, and the effective EMCC of transducers varies with the material of metal cylindrical shell, in which aluminum metal shell possesses the highest EMCC.

Enhancing the bandwidth of piezoelectric composite transducers for air-coupled non-destructive evaluation

This paper details the development of a novel method for increasing the operational bandwidth of piezocomposites without the need for lossy backing material, the aim being to increase fractional bandwith by geometrical design. Removing the need for lossy backing materials, should in turn increase the transmit efficiency in the desired direction of propagation. Finite element analysis has been employed to determine the mode of operation of the new piezocomposite devices and shows good correlation with that derived experimentally. Through a series of practical and analytical methods it has been shown that additional thickness mode resonances can be introduced into the structure by a simple machining process. The shaped composites described in this paper offer increased operational bandwidth. A simple example of a two step thickness design is described to validate and illustrate the principle. A more complex conical design is presented that illustrates a possible tenfold increase in bandwidth from 30kHz to 300kHz, operating in air without backing. An illustration of the applicability of this type of transducer technology for frequency agile guided mode non-destructive evaluation is then presented.

Long-term fatigue behavior of a cantilever piezoelectric energy harvester

Piezoelectric energy harvesting has attracted extensive research in the advancement of new designs and techniques over the last decade. The cantilever shaped piezoelectric energy harvesting beam is one of the most employed designs, due to its simplicity and flexibility for further performance enhancement. The strain distribution along the cantilever piezoelectric energy harvesting beam is nonuniform, which would induce fatigue damage at the root of the cantilever on the long run. This particular issue has seldom been addressed in the literature. This article presents an experimental investigation on the fatigue behavior of a cantilever piezoelectric energy harvesting beam at different base excitation levels. The experimental study is augmented with analytical formulation to examine the strain levels and with finite element analysis formulation to model the piezoelectric energy harvesting beam with a macro fiber composite piezoelectric transducer. A two-dimensional model is developed based on the three-dimensional model to investigate crack propagation in the piezoelectric energy harvesting beam. Furthermore, the electromechanical impedance technique is employed to monitor the progression of damage in the experimental specimens. The root mean square deviation and relative root mean square deviation of the impedance values and voltage obtained from the macro fiber composite transducer provide a profound introspection into the damage propagation in the piezoelectric energy harvesting beam. This study provides an insight into the behavior of the piezoelectric energy harvesting beam undergoing fatigue loading due to a uniform sinusoidal base excitation by analyzing the output voltage, resonant frequency, tip displacement, tip velocity, and impedance variations. It will pave the way for future studies on the fatigue-based design guides for piezoelectric energy harvesting beams.

Wireless Power Transmission Based on Sandwiched Composite Piezoelectric Transducers in Length Extensional Vibration

A new type of wireless power transmission system is proposed. It is composed of two sandwiched composite piezoelectric transducers in length extensional vibration, which are connected together by an intermediate metal transmission cylinder. When the dielectric and mechanical losses are considered, the resonance/antiresonance frequency equations are obtained. The effect of the mechanical and the dielectric loss, the geometrical dimension and the load electric impedance on the effective electromechanical coupling coefficient, the voltage gain, and the power ratio is analyzed. It is shown that the mechanical and the dielectric losses almost have no effect on the resonance/antiresonance frequency. The geometrical dimension has obvious effect on the resonance/antiresonance frequency, the voltage gain, the effective electromechanical coupling coefficient and the power ratio. Corresponding to definite geometrical dimensions, the effective electromechanical coupling coefficient and the voltage gain have maximum values. There is optimum load electric impedance at which the power ratio reaches the maximum value. Two wireless power transmission systems are designed and manufactured; the resonance/antiresonance frequencies, the voltage gain, and the power ratio are measured. It is shown the measured frequencies are in good agreement with the theoretical results.

Conception of the system for traffic measurements based on piezoelectric foils

A concept of mechatronic system for traffic measurements based on the piezoelectric transducers used as sensors is presented. The aim of the work project is to theoretically and experimentally analyse the dynamic response of road infrastructure forced by vehicles motion. The subject of the project is therefore on the borderline of civil engineering and mechanical and covers a wide range of issues in both these areas. To measure the dynamic response of the tested pieces of road infrastructure application of piezoelectric, in particular piezoelectric transducers in the form of piezoelectric films (MFC - Macro Fiber Composite) is proposed. The purpose is to verify the possibility to use composite piezoelectric transducers as sensors used in traffic surveillance systems - innovative methods of controlling the road infrastructure and traffic. Presented paper reports works that were done in order to receive the basic information about analysed systems and their behaviour under excitation by passing vehicles. It is very important to verify if such kind of systems can be controlled by the analysis of the dynamic response of road infrastructure measured using piezoelectric transducers. Obtained results show that it could be possible.

Design of an Orthotropic Piezoelectric Composite Material Phased Array Transducer for Damage Detection in a Concrete Structure

ABSTRACTIn order to verify the feasibility and effectiveness of the sensor used in complex concrete materials, an innovative application of ultrasonic phased array detection for a concrete structure was investigated. Comparing with the traditional piezoelectric composites, orthotropic piezoelectric composite material (OPCM) can be used as transducers in damage detection show clear advantages because of their high sensitivity and directivity along the polarization direction. A low frequency ultrasonic phased array transducer consisting of 16 OPCM elements is studied. The optimal array parameters, such as the phased array element interval, the array element width, and number of elements, are obtained by studying the total displacement changes as various parameters change at the focus point in the concrete structure. This configuration allowed the variation and control of the wave field directivity in the concrete structure during the measurements. The measurements were taken on concrete specimens using a precise time-delay device. The experimental measurements were compared to theoretical calculations to investigate the influence of different array element parameters. The results show that an OPCM phased array transducer can be used to detect damage in a concrete block.

Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer for Air-Coupled Ultrasonic Applications

The air-based 1-3 piezoelectric composite transducers are designed and fabricated in order to solve the acoustic impedance matching problem. Firstly, a finite element model using honeycomb structure as the piezoelectric composite matrix is built to reduce the acoustic impedance of the sensitive element. Three important factors, volume fraction of piezoelectric materialsφ, the thicknessh, and the sizesof the square cross section of piezoelectric column, are examined and verified in simulation. Then, according to the result of simulation, the piezoelectric composites and the air-coupled transducers are fabricated. The honeycomb structures of resin are produced by the method of 3D printing technology, with the volume fraction of air being 30%. The impedance characteristics and the excitation/reception performance of the air-coupled transducers are measured and optimized. Meanwhile, a scanning experiment is carried out to demonstrate the crack detection process in monocrystalline silicon.A0mode of Lamb waves is excited and collected. The location and size of the defect will be determined by calculating the correlation coefficients of the received signals and reference signals. Finally, a 15 mm × 0.5 mm × 0.5 mm scratch is clearly distinguished.

Radial Vibration of a Regular Polygon Composite Piezoelectric Ultrasonic Transducer

Radial Vibration of a Regular Polygon Composite Piezoelectric Ultrasonic Transducer

Optimum Operating Conditions of (PbxX1−x)(ZryTizY1−y−z) Piezoelectric Transducer for Vibrational Energy Harvesting Applications

The electrical energy production capability of bimorph (PbxX1-x)(ZryTizY1-y-z) fiber composite piezoelectric transducer has been investigated for energy harvesting applications. The material has been analyzed under different frequencies, bending amounts, and temperatures. The operating conditions for maximum electrical energy outcome have been determined. The natural frequencies of oscillations in the macro dimensions have been found to be inversely proportional to the length of the material. On the other hand, the voltage output with respect to the oscillation frequency exhibits an interesting behavior such that the characteristic curve shifts to higher frequencies as the bending radius is decreased. This behavior has been interpreted as a result of possible overtone transitions of the oscillations to a stiffer mode. The increasing temperature has been observed to have a negative effect on the piezoelectric energy harvesting property. When the determined optimum conditions were utilized, the amount of electrical energy stored in 6300 s by an energy harvester circuitry has been found to be 0.8 J.

Influence of the excitation parameters of the mechanical subsystem on effectiveness of energy harvesting system

Piezoelectric transducers are used more and more often in modern technical devices. The wide range of their possible applications is a result of the possibility to use both direct and reverse piezoelectric effect. Nowadays, application of piezoelectric transducers in energy harvesting systems is getting more and more popular. It is caused by the easy way to convert energy of mechanical vibration to the electric voltage using piezoelectric transducers. This paper presents results of influence analysis of the vibrating mechanical subsystem's excitation parameters on the effectiveness of the system designed for energy harvesting. The considered vibrating system is a composite plate with piezoelectric transducer bonded to its surface. Vibrations of the system are excited by means of an actuator with possibility to change the excitation amplitude and frequency. Recovering of electrical energy from mechanical vibrations is possible by using the direct piezoelectric effect - generation of the electric voltage while the transducer is mechanically deformed. In carried out test Macro Fiber Composite (MFC) piezoelectric transducers were used. It was proved that the time that is necessary for switch on the output voltage in analyzed system depends on the frequency of the excitation.