Piezoelectric Macro Fiber Composite Research Articles

Shape optimization of a non-uniform piezoelectric bending beam for human knee energy harvester

Abstract Scavenging energy from the human body to provide a sustainable source for electronic devices has gained significant attention. Recently, scientists have focused on harnessing biomechanical energy from human motion. This study was dedicated to developing and optimizing a non-uniform piezoelectric bending beam-based human knee energy harvester. The bimorph non-uniform piezoelectric bending beam consisted of a non-uniform carbon fiber substrate and piezoelectric macro fiber composites. Compared to the uniform piezoelectric bending beam, the non-uniform piezoelectric beam can optimize the shape to improve the average strain, thus improving the energy harvesting efficiency. In this study, eight shape functions, including ellipse, sin, tanh, exponential function, parabola, trigonometric line, and bell curves, were investigated and optimized. The bell curve bending beam was selected and fabricated due to its good performance. Then, a benchmark platform was developed to test the deflection curve and reaction force when the nonuniform bending beam was compressed. Finally, to validate the design, experimental testing on three subjects was conducted when they were equipped with the harvester and walked on a treadmill. Testing results indicated that the non-uniform bending beam-based energy harvester can improve the energy harvesting efficiency by 28.57% compared to the uniform beam-based energy harvester. The output power can reach 18.94 mW when walking at 7.0 km h−1.

An improved active damping of fan blade using piezoelectric MFC actuators and PSO optimization

This study introduces piezoelectric actuators for blade vibration control and aims to establish both experimental and numerical benchmarks for active vibration control with macro fiber composite (MFC) piezoelectric actuators on engine blades. It also involves optimizing the placement of MFC actuators. Experimental and numerical assessments were conducted on a 3D-printed fan model with integrated piezoelectric MFC actuators. The results confirm the effectiveness of the proposed approach, aided by a PID controller, in significantly reducing and damping blade vibrations. This comprehensive study offers a promising solution to enhance aviation engine performance and longevity.

Simulation and Experiment of Active Vibration Control Based on Flexible Piezoelectric MFC Composed of PZT and PI Layer.

In order to improve the vibration suppression effect of the flexible beam system, active control based on soft piezoelectric macro-fiber composites (MFCs) consisting of polyimide (PI) sheet and lead zirconate titanate (PZT) is used to reduce the vibration. The vibration control system is composed of a flexible beam, a sensing piezoelectric MFC plate, and an actuated piezoelectric MFC plate. The dynamic coupling model of the flexible beam system is established according to the theory of structural mechanics and the piezoelectric stress equation. A linear quadratic optimal controller (LQR) is designed based on the optimal control theory. An optimization method, designed based on a differential evolution algorithm, is utilized for the selection of weighted matrix Q. Additionally, according to theoretical research, an experimental platform is built, and vibration active control experiments are carried out on piezoelectric flexible beams under conditions of instantaneous disturbance and continuous disturbance. The results show that the vibration of flexible beams is effectively suppressed under different disturbances. The amplitudes of the piezoelectric flexible beams are reduced by 94.4% and 65.4% under the conditions of instantaneous and continuous disturbances with LQR control.

Dynamic analysis of graphene-reinforced sandwich plates with piezoelectric macro fiber composite face sheets

Graphene is considered as an ideal candidate for composite materials owing to the outstanding physical characteristics. However, existing higher-order shear deformation theories in the literature may meet severe challenges for the accurate prediction of natural frequencies of graphene-reinforced sandwich plates with piezoelectric macro fiber composite (MFC) face sheets. If transverse shear deformations cannot be described accurately, the dynamic behaviors of piezoelectric sandwich plates with graphene reinforcements will be significantly impacted by the large differences of material properties at interfaces of adjacent layers and electro-mechanical coupling characteristic. Thereby, a novel electro-mechanical coupling theory is to be proposed for the free vibration of graphene-reinforced sandwich plates with MFC face sheets. Based on the Reissner mixed variational theorem (RMVT), the precision of the interlaminar shear stresses including the electro-mechanical coupling effect can be improved. The modified interlaminar shear stress field is absorbed in the strain energy, which can enhance the accuracy of the free vibration response of piezoelectric sandwich plates. Additionally, the second-order derivatives of in-plane displacements have been eliminated from the interlaminar shear stress components, which can substantially simplify the finite element implementation. Thus, a simple C0-type finite element formulation is developed for the free vibration of piezoelectric sandwich plates with graphene reinforcements. The 3D elasticity solutions and the results obtained from other theories are used to evaluate the performance of the proposed theory. In comparison with the existing higher-order theories, the proposed theory can produce more accurate results. In addition, a comprehensive parametric study is conducted to explore the impacts of significant parameters on the free vibration behaviors of piezoelectric graphene-reinforced sandwich plates.

Selection of piezoeloectric material and fiber volume fraction to maximize the electrical power produced by macro-fiber composite energy harvesters

A piezoelectric Macro fiber composite (MFC) materials developed in the last decade found widespread applications such as vibration sensing, actuation and structural health monitoring. Unlike conventional ceramic piezoelectric materials (PZT), these composites show many advantages such as flexibility, reliability and high actuation capacity. However, increasing their energy harvesting capabilities still remains a challenge. Modeling and simulation of electrical energy harvesters using MFC patches provide a mean for geometrical optimization and appropriate choice of the MFC composite. This paper proposes a linear analytical model for prediction of the electro-mechanical response of bimorph harvesters using MFC patches. Homogenization technique is used to describe the equivalent piezoelectric properties of the composite structure of the MFC patch. This paper investigates the effect of the volume fraction of the fibers and the material choice of the piezoelectric fibers and epoxy matrix on the generated electrical power. It has been found that an increased fiber volume fraction causes a decrease of the voltage, the power and the velocity amplitudes for a range of load resistance. However, an increase in the fiber volume fraction FVF is achieved by an increase of the current amplitude for a range of load resistance. Maximum amount of power is generated by the bimorph MFC harvester for an FVF of 86% which corresponds to the reference configuration. The piezoelectric fiber material has a significant influence on the output power. In fact, the SONOX-P502 generated the greatest electrical power. However, the material of the matrix has a negligible effect on the generated power.

Ultrasonic-based tensile force estimation for cylindrical rod at various temperature conditions

This study presents the development of a tensile force estimation technique based on the ultrasonic bulk wave for cylindrical rod in a suspension bridge anchor system. Three piezoelectric macro fiber composites (MFC) transducers are installed on the surface of a cylindrical rod specimen for the generation and sensing of ultrasonic bulk waves. Ultrasonic responses are obtained at various tensile force levels and temperature conditions, and the relationship between the time lag of the ultrasonic response and the tensile force is established. In particular, the temperature effect on the tensile force estimation is theoretically derived and compensated for field applications. The originality of this study includes (1) theoretical derivation and investigation of the relationship between an applied tensile force level and the time lag of an ultrasonic response considering the variations of temperature, density, and elastic modulus, (2) development of a tensile force estimation and temperature compensation technique without temperature measurement, and (3) application to the tensile force estimation of the rod structure commonly used in a suspension bridge anchor system. The performance of the developed tensile force estimation technique was examined based on mock-up experiments of the rod structure of a real suspension bridge anchor system.

Lightweight Piezoelectric Bending Beam-Based Energy Harvester for Capturing Energy From Human Knee Motion

Harvesting energy from the human body has attracted substantial attention from industries and academics as it is a promising solution to address the battery life issue. In this article, we developed a bimorph piezoelectric bending beam-based energy harvester to scavenge energy from the human knee motion for powering body-worn electronics such as smartwatches and health monitors. During walking, the human knee will flex and extend to periodically deform piezoelectric macro fiber composites (MFC) bounded to the bending beam, thus generating electricity. The mathematical models of the whole system including the model of the large deflection of the bending beam, movement analysis of the end of the bending beam (slider-crank mechanism), the model of piezoelectric transducers, and measurement of the human knee angle are developed to comprehensively study the harvester. To validate the presented mathematical models, experimental testing on a human body when the subject walks on a treadmill at three different walking speeds is conducted here. The experimental results show good agreement with the simulation results, which indicates that the developed models can characterize the harvester. In addition, the performance of the harvester walking in different contexts is also evaluated. The average power can reach 12.79 mW for level-ground walking, 9.91 mW for stair descending, and 7.70 mW for stair ascending, when walking at a self-selected speed.

A Hybrid Structure of Piezoelectric Fibers and Soft Materials as a Smart Floatable Open-Water Wave Energy Converter.

An open-water wave energy converter (OWEC) made of a new soft platform has been developed by combining piezoelectric macro-fiber composites (MFCs) and a low-cost elastomer. In the past decades, numerous types of water wave energy conversion platform have been developed and investigated, from buoys to overtopping devices. These harvesters mainly use electromagnetic-based generators, and they have faced challenges such as their enormous size, high deployment and maintenance costs, and negative effects on the environment. These problems hinder their practicality and competitiveness. In this paper, a soft open-water wave energy converter is introduced which integrates piezoelectric MFCs and bubble wrap into an elastomer sheet. The performance of the OWEC was investigated in a wave flume as a floatable structure. The maximum 29.7 µW energy harvested from the small OWEC represents a promising energy conversion performance at low frequencies (<2 Hz). The elastomer was able to protect the MFCs and internal electrical connections without any degradation during the experiment. In addition, the OWEC is a foldable structure, which can reduce the deployment costs in real-world applications. The combination of no maintenance, low fabrication cost, low deployment cost, and moderate energy harvesting capability may advance the OWEC platform to its real-world applications.

A Micro-Power Generator Based on Two Piezoelectric MFC Films

In order to realize the collection of micro or small vibration energy, a micro-power generator based on two piezoelectric Macro Fiber Composite (MFC) films is proposed. The piezoelectric generator consists of a double piezoelectric MFCs type vibrator and a displacement amplifying mechanism, which can achieve the output of high energy density. The design process of this kind of piezoelectric generator is presented. Based on LabVIEW platform and NI Data Acquisition (DAQ) card, the output voltage acquisition system of the generator is built, and the output voltage and power are collected and calculated. Experimental results show that the maximum output power is 6.2 mW under transient excitation. Under continuous excitation with a load resistance of 10 kΩ and an excitation frequency of 26 Hz, the maximum output of the generator is up to 11.9 mW. The research results lay a foundation for the application of the proposed micro-power piezoelectric generator.

Uncertainty quantification and global sensitivity analysis of piezoelectric energy harvesting using macro fiber composites

Piezoelectric macro fiber composites (MFCs) are widely used for energy harvesting due to their flexibility and high electromechanical conversion efficiency. In previous research studies, numerical and analytical models have been developed for MFC-harvesters using homogenized electromechanical properties. In this paper, an analytical electroelastic coupled model, based on the mixing rules, is used to predict the output responses of an MFC-harvester coupled in 33-mode of the PZT fibers. The predicted responses exhibit variation because of the uncertainty of the parameters used in the proposed model. The research reported in this paper aims to estimate the effect of the uncertainty in the physical properties of both piezoelectric fibers and epoxy matrix on the model responses and to identify the parameters which cause large output variability. The uncertainties of the parameters are defined as the variability bounds based on the tolerances reported by the manufacturers. Global sensitivity analysis (GSA) is an appropriate method to study the effect of the uncertainty of parameters on the electromechanical response of the harvester. Two GSA are applied in this paper: (i) the Morris method based on the elementary effects measures and (ii) the variance method which consists in computing the Sobol’ indices, whose goal is to identify systems parameters which have significant impact on the voltage and the power outputs of a bimorph MFC-harvester. This study leads to a qualitative comparison between the two methods which are strategically different. Both methods indicate that the elastic modulus and the density of the piezoelectric fibers, the length and the thickness of the representative volume element of the MFC-patch are the most influential parameters that affect the output voltage. It has also been shown that the order of importance of the parameters can change from the short-circuit to the open-circuit condition. Furthermore, Monte Carlo simulations are used to propagate the uncertainties of the parameters in order to determine the envelope of the variability of the responses. This study reveals the importance of considering model parameter uncertainties in the development of robust prediction tools for piezoelectric energy harvesting devices.

Bio-inspired bi-stable piezoelectric harvester for broadband vibration energy harvesting

Inspired by the rapid shape transition of the Venus flytrap, a novel low-cost, bi-stable piezoelectric energy harvester is proposed, analyzed, and experimentally tested for the purpose of broadband energy harvesting. The harvester consists of a piezoelectric macro fiber composite (MFC) transducer, a tip mass, and two sub-beams with bending and twisting deformations created by pre-displacement constraints at the free ends using rigid tip-mass blocks. Different from bi-stable harvesters realized by nonlinear magnetic forces or residual stresses in laminate composites, the bio-inspired bi-stable piezoelectric energy harvester stores the potential energy induced by the mutual self-constraint of the sub-beams and harvests the large energy released during the rapid shape transition. Detailed design steps and principles are introduced and a prototype is fabricated to demonstrate and validate the concept. The experimentally measured nonlinear force–displacement curve of the harvester exhibits a discontinuous feature as the harvester jumps between the stable states. The dynamics of the proposed bio-inspired bi-stable piezoelectric energy harvester is investigated under sweeping frequency and harmonic excitations. The results show that the sub-beams of the harvester experience local vibrations including broadband high-frequency oscillations during the snap-through. The energy harvesting performance of the harvester is evaluated at different excitation levels over the frequency range of 9.0–14.0 Hz. Broadband energy harvesting is attained at relatively high excitation levels. An average power output of 0.193 mW for a load resistance of 8.2 kΩ is harvested at the excitation frequency of 10 Hz and amplitude of 4.0 g.

Self-sensing piezoelectric bistable laminates for morphing structures

Bistable laminates offer opportunities for shape morphing, energy harvesting, and flow control devices. Smart materials such as piezoelectric macrofiber composites and shape memory alloys have been embedded in bistable laminates to actuate or harvest energy. However, sensor systems capable of measuring bistable shapes and snap-through events are lacking. In this paper, we present curved bistable laminates layered with piezoelectric PVDF films that can sense smooth shape changes as well as abrupt snap-through transitions. Near-static measurement is facilitated by a drift compensated charge amplifier with a large time constant that converts the sensor’s charge output into a measurable voltage with minimal drift error. The sensing function is demonstrated on mechanically-prestressed bistable laminates. The laminated composites include two sensor layers such that one measures the changes in curvature and the other measures snap-through events. An analytical model is presented in which strains and curvatures calculated using a laminated-plate model are fed into a linear piezoelectric model to calculate voltage. Shapes measured by the sensors correlate well with shapes measured using a 3D motion capture system. A model-based analysis is performed to understand the laminates’ design space.

Wind energy harvesting using piezoelectric macro fiber composites based on flutter mode

Mechanical energy such as the wind flow widely exists in nature as renewable and sustainable energy source. It could be converted into electrical energy throughout piezoelectricity which has capability for converting mechanical energy into electrical energy. In this paper, an innovation piezoelectric energy harvesting (PEH) system is proposed by using the piezoelectric macro fiber composites (MFC) based on flutter mode. It is demonstrated that this PEH-MFC system exhibits the excellent characteristic of flexibility on large deformation and reliability in energy harvesters and effectively captures power from wind energy. The PEH-MFC system is composed of a soft substrate linked with a polymer triangular leaf by a copper hinge. The active MFC is attached at the bottom of the soft substrate as the core component of system. A series of experiments on energy harvesting systems for various substrate materials and various types of MFC are performed in wind tunnel. The flutter mode is obtained under the critical flutter wind speed in order to acquire the excellent behavior of extracting power through this innovation PEH-MFC system. The experimental results show that the thickness and stiffness of PEH substrate have significant effects on the performance of energy harvesting. The maximum peak-to-peak open circuit voltage of 82 V is obtained using the MFC-2807 with Al substrate at the wind speed of 7.5 m/s. The resulting direct voltage and electric power are 25.8 V and 0.54 mW with a load resistance of 680 kΩ, respectively. It is concluded that the proposed energy harvesting system using MFC based on flutter mode can generate a power efficiency of 9.18 mW/cm3 which can meet the requirement of conventional MEMS.

Active vibration control analysis in smart composite structures using ANSYS

Piezoelectric Macro-Fiber Composite (MFC) utilization is increasing in engineering fields due to its strong actuation forces and high flexibility. In this paper, piezoelectric ( ) type (M8528-P1) patches are applied for active control of a cantilever composite beam. A linear coupled finite element model for piezoelectric MFC actuation of the composite beam was developed based on the APDL-ANSYS codes by using linear piezoelectric constitutive equations to study smart composite beam behavior in open and closed-loop cases. Active vibration control response of laminated composite beams with various stacking sequence configurations was examined, and the results were compared. In this, the proportional type (kp) of control algorithms is utilized, and in the summary of work refined two sets of finite element models. The first set their laminates to have an orientation (0 with 90), and others have an orientation (0 with 45). When the control signal applied with the gain (kp) to a system increases, the rise time generally decreases, the actuator voltages for different control gain for all cases are observed with the increase in the proportional constant. The findings of this study indicate that the composite beams composed from (0/90) stacking sequence sets had reached stability state faster than the composite beams composed from (0/45) stacking sequence sets.

Applications of piezoelectric MFC type transducers in mechatronic measurement systems - the impact of a mechanical subsystem damage on a system operation

The work include a report of research works concerning applications of non-classical piezoelectric transducers in mechatronic measuring systems. Composite piezoelectric transducers called Macro Fiber Composite (MFC) are considered. Characteristics of considered transducers were made, indicating their advantages and disadvantages, as well as the results of carried out laboratory tests are presented, in which MFC transducers were used as sensors for mechatronic measurement systems. A series of laboratory tests was carried out on the created laboratory stand to determine the impact on the measured values of damage of the mechanical subsystem on which the MFC-type piezoelectric transducer was glued. Results of measurements are presented and analysed in relation to different applications of the piezoelectric MFC sensors.

Improved analytical homogenization of the piezoelectric macro-fiber composite: active layer embedded among passive layers

Predicting the effective electromechanical properties for piezoelectric fiber composite patches is crucial for analysis of smart structures equipped with such patches. In particular, analytical homogenization models are attractive but are limited by the complexity of the microstructure and the multiphysics involved. The macro-fiber composite (MFC) has emerged as the most popular piezoelectric fiber composite. But typical reports of its effective properties provide layerwise homogenization with low-order mechanical plate theories. This approach discards most of the out-of-plane properties and may introduce significant error from the assumptions about the plate kinematics. Moreover, the effective permittivities of the transducer are not available analytically. In an attempt to overcome these limitations, a new analytical scheme for homogenizing all layers in the MFC patch is proposed. Based on the newly discovered mechanics of structure genome, we avoid all kinematical assumptions and obtain an exact analytical solution for a periodic, multi-layered, linear-piezoelectric material. In doing so, we prove that in any such multi-layered composite, the in-plane strains and the transverse stresses are equal in each layer and the in-plane electric fields and transverse electric displacement are constant between the electrodes. Using this knowledge, a hybrid rule of mixtures is developed to homogenize all the MFC layers to obtain the complete set of properties of the full MFC. In doing the new analytical framework can homogenize any layered piezoelectric medium. Finally, since we were able to avoid the plate-kinematics assumptions, we present studies on their effect on the properties they obtain. We find that the in-plane elastic properties are not affected but the transverse shear moduli are overpredicted from 100% to 300%. What is more, studies are presented on how using the ubiquitous plane-stress-like assumptions to homogenize the fiber layers causes an 8% underprediction of the lateral elastic modulus of the MFC.

Stacked PZT Discs Generate Necessary Power for Bone Healing through Electrical Stimulation in a Composite Spinal Fusion Implant.

Electrical stimulation devices can be used as adjunct therapy to lumbar spinal fusion to promote bone healing, but their adoption has been hindered by the large battery packs necessary to provide power. Piezoelectric composite materials within a spinal interbody cage to produce power in response to physiological lumbar loads have recently been investigated. A piezoelectric macro-fiber composite spinal interbody generated sufficient power to stimulate bone growth in a pilot ovine study, despite fabrication challenges. The objective of the present study was to electromechanically evaluate three new piezoelectric disc composites, 15-disc insert, seven-disc insert, and seven-disc Compliant Layer Adaptive Composite Stack (CLACS) insert, within a spinal interbody, and validate their use for electrical stimulation and promoting bone growth. All implants were electromechanically assessed under cyclic loads of 1000 N at 2 Hz, representing physiological lumbar loading. All three configurations produced at least as much power as the piezoelectric macro-fiber composites, validating the use of piezoelectric discs for this application. Future work is needed to characterize the electromechanical performance of commercially manufactured piezoelectric stacks under physiological lumbar loads, and mechanically assess the composite implants according to FDA guidelines for lumbar interbody fusion devices.

High Power Magnetic Field Energy Harvesting through Amplified Magneto‐Mechanical Vibration

AbstractInternet of Things (IoT) is driving the development of new generation of sensors, communication components, and power sources. Ideally, IoT sensors and communication components are expected to be powered by sustainable energy source freely available in the environment. Here, a breakthrough in this direction is provided by demonstrating high output power energy harvesting from very low amplitude stray magnetic fields, which exist everywhere, through magnetoelectric (ME) coupled magneto‐mechano‐electric (MME) energy conversion. ME coupled MME harvester comprised of multiple layers of amorphous magnetostrictive material, piezoelectric macrofiber composite, and magnetic tip mass, interacts with an external magnetic field to generate electrical energy. Comprehensive experimental investigation and a theoretical model reveal that both the magnetic torque generated through magnetic loading and amplification of magneto‐mechanical vibration by ME coupling contributes toward the generation of high electrical power from the stray magnetic field around power cables of common home appliances. The generated electrical power from the harvester is sufficient for operating microsensors (gyro, temperature, and humidity sensing) and wireless data transmission systems. These results will facilitate the deployment of IoT devices in emerging intelligent infrastructures.

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.

Implementation of a Hybrid Electro-Active Actuated Morphing Wing in Wind Tunnel

Amongst current aircraft research topics, morphing wing is of great interest for improving the aerodynamic performance. A morphing wing prototype has been designed for wind tunnel experiments. The rear part of the wing - corresponding to the retracted flap - is actuated via a hybrid actuation system using both low frequency camber control and a high frequency vibrating trailing edge. The camber is modified via surface embedded shape memory alloys. The trailing edge vibrates thanks to piezoelectric macro-fiber composites. The actuated camber, amplitude and frequency ranges are characterized. To accurately control the camber, six independent shape memory alloy wires are controlled through nested closed-loops. A significant reduction in power consumption is possible via this control strategy. The effects on flow via morphing have been measured during wind tunnel experiments. This low scale mock-up aims to demonstrate the hybrid morphing concept, according to actuator capabilities point of view as well as aerodynamic performance.