A bimorph piezoelectric beam with periodically variable cross-sections is used for the vibration energy harvesting. The effects of two geometrical parameters on the first band gap of this periodic beam are investigate...A bimorph piezoelectric beam with periodically variable cross-sections is used for the vibration energy harvesting. The effects of two geometrical parameters on the first band gap of this periodic beam are investigated by the generalized differential quadrature rule (GDQR) method. The GDQR method is also used to calculate the forced vibration response of the beam and voltage of each piezoelectric layer when the beam is subject to a sinusoidal base excitation. Results obtained from the analytical method are compared with those obtained from the finite element simulation with ANSYS, and good agreement is found. The voltage output of this periodic beam over its first band gap is calculated and compared with the voltage output of the uniform piezoelectric beam. It is concluded that this periodic beam has three advantages over the uniform piezoelectric beam, i.e., generating more voltage outputs over a wide frequency range, absorbing vibration, and being less weight.展开更多
To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments...To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments are performed to verify theoretical analysis.When the excitation direction is along Y direction,a maximal output power about 0.139 mW can be harvested at a resistive load of 65kΩ and an excitation frequency of 136 Hz.Theoretical analysis agrees well with experimental results.Furthermore,the performance of multi-direction vibration energy harvester is experimentally tested.The results show that the multi-direction vibration energy harvester can harvest perfect energy as the excitation direction changes in XY plane,YZ plane,XZ plane and body diagonal plane of the harvester.展开更多
Vibration energy harvesters(VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applicati...Vibration energy harvesters(VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applications of a micro-electro-mechanical system(MEMS). However, the ambient vibration is always too weak to hinder the high energy conversion efficiency. In this paper, the integrated frame composed of piezoelectric beams and mechanical amplifiers is proposed to improve the energy conversion efficiency of a VEH. First, the initial structures of a piezoelectric frame(PF) and an amplification frame(AF) are designed. The dynamic model is then established to analyze the influence of key structural parameters on the mechanical amplification factor. Finite element simulation is conducted to study the energy harvesting performance, where the stiffness characteristics and power output in the cases of series and parallel load resistance are discussed in detail. Furthermore, piezoelectric beams with variable cross-sections are introduced to optimize and improve the energy harvesting efficiency. Advantages of the PF with the AF are illustrated by comparison with conventional piezoelectric cantilever beams. The results show that the proposed integrated VEH has a good mechanical amplification capability and is more suitable for low-frequency vibration conditions.展开更多
Vibration energy harvesting has emerged as a promising method to harvest energy for small-scale applications.Enhancing the performance of a vibration energy harvester(VEH)incorporating nonlinear techniques,for example...Vibration energy harvesting has emerged as a promising method to harvest energy for small-scale applications.Enhancing the performance of a vibration energy harvester(VEH)incorporating nonlinear techniques,for example,the snap-through VEH with geometric non-linearity,has gained attention in recent years.A conventional snap-through VEH is a bi-stable system with a time-invariant potential function,which was investigated extensively in the past.In this work,a modified snap-through VEH with a time-varying potential function subject to harmonic and random base excitations is investigated.Modified snap-through VEHs,such as the one considered in this study,are used in wave energy harvesters.However,the studies on their dynamics and energy harvesting under harmonic and random excitations are limited.The dynamics of the modified snap-through VEH is represented by a system of differential algebraic equations(DAEs),and the numerical schemes are proposed for its solutions.Under a harmonic excitation,the system exhibits periodic and chaotic motions,and the energy harvesting is superior compared with the conventional counterpart.The dynamics under a random excitation is investigated by the moment differential method and the numerical scheme based on the modified Euler-Maruyama method.The Fokker-Planck equation representing the dynamics is derived,and the marginal and joint probability density functions(PDFs)are obtained by the Monte Carlo simulation.The study shows that the modified snap-through oscillator based VEH performs better under both harmonic and random excitations.The dynamics of the system under stochastic resonance(SR)is investigated,and performance enhancement is observed.The results from this study will help in the development of adaptive VEH techniques in the future.展开更多
We demonstrate a piezoelectric vibration energy harvester with the ZnO piezoelectric film and an improved synchronous electric charge extraction energy harvesting circuit on the basis of the beam-type mechanical struc...We demonstrate a piezoelectric vibration energy harvester with the ZnO piezoelectric film and an improved synchronous electric charge extraction energy harvesting circuit on the basis of the beam-type mechanical structure,especially investigate its output performance in vibration harvesting and ability to generate charges.By establishing the theoretical model for each of vibration and circuit,the numerical results of voltage and power output are obtained.By fabricating the prototype of this harvester,the quality of the sputtered film is explored.Theoretical and experimental analyses are conducted in open-circuit and closed-circuit conditions,where the open-circuit mode refers to the voltage output in relation to the ZnO film and external excitation,and the power output of the closed-circuit mode is relevant to resistance.Experimental findings show good agreement with the theoretical ones,in the output tendency.It is observed that the properties of ZnO film achieve regularly direct proportion to output performance under different excitations.Furthermore,a maximum experimental power output of 4.5 mW in a resistance range of 3 kΩ-8 kΩis achieved by using an improved synchronous electric charge extraction circuit.The result is not only more than three times the power output of classic circuit,but also can broaden the resistance to a large range of 5 kΩunder an identical maximum value of power output.In this study we demonstrate the fundamental mechanism of piezoelectric materials under multiple conditions and take an example to show the methods of fabricating and testing the ZnO film.Furthermore,it may contribute to a novel energy harvesting circuit with high output performance.展开更多
With the rapid development of microelectronics and flexible electronics technology,self-powered sensors have significant application prospects in human-machine interface systems and Internet of Things.However,piezoele...With the rapid development of microelectronics and flexible electronics technology,self-powered sensors have significant application prospects in human-machine interface systems and Internet of Things.However,piezoelectric-and triboelectricbased sensors have low current output and are easily affected,while electromagnetic-based sensors are difficult to miniaturize.This work proposes a high-density stacked microcoil integrated microminiaturized electromagnetic vibration energy harvester(EVEH).The double-layer high-density microcoil is fabricated on both sides of the flexible polyimide substrate interconnected via the central through-hole.Owing to reduced single coil line width,line spacing,and stacked structure,the number of turns can be substantially enhanced.Moreover,the relative position of the coils and magnet has a considerable influence on the performances;due to the huge change rate in magnetic flux when the coil is placed in the radial direction of the magnet than in the axial direction,the open-circuit voltage in the radial direction is 10 times greater.The microcoil can maintain good performance at high,low temperatures and under bending conditions.When the distance between the ends of the coil changes from 2 to 20 mm in 2 mm steps,the bending angle of the coil changes from 45°to 270°in 45°steps;furthermore,when the coil is exposed to-40and 60℃conditions,the coil resistance is maintained at approximately 447Ω.The peak open-circuit voltage of three-piece microcoils reaches 0.41 V at 4 Hz under 2g,and the output voltage and current increase with an increasing number of stacked layers.These excellent properties indicate that EVEH can be used for self-powered acceleration sensing.The sensitivity is measured to be 0.016 V/(m/s^(2))with a correlation coefficient of 0.979 over the acceleration range of 1–18 m/s^(2).Thus,the developed microminiaturized EVEH has enormous potential for self-powered sensing applications in confined spaces and harsh environments.展开更多
Because of the increasing demand for electrical energy,vibration energy harvesters(VEHs)that convert vibratory energy into electrical energy are a promising technology.In order to improve the efficiency of harvesting ...Because of the increasing demand for electrical energy,vibration energy harvesters(VEHs)that convert vibratory energy into electrical energy are a promising technology.In order to improve the efficiency of harvesting energy from environmental vibration,here we investigate a hybrid VEH.Unlike previous studies,this article analyzes the stochastic responses of the hybrid piezoelectric and electromagnetic energy harvesting system with viscoelastic material under narrow-band(colored)noise.Firstly,a mass-spring-damping system model coupled with piezoelectric and electromagnetic circuits under fundamental acceleration excitation is established,and analytical solutions to the dimensionless equations are derived.Then,the formula of the amplitude-frequency responses in the deterministic case and the first-order and secondorder steady-state moments of the amplitude in the stochastic case are obtained by using the multi-scales method.The amplitude-frequency analytical solutions are in good agreement with the numerical solutions obtained by the Monte Carlo method.Furthermore,the stochastic bifurcation diagram is plotted for the first-order steady-state moment of the amplitude with respect to the detuning frequency and viscoelastic parameter.Eventually,the influence of system parameters on mean-square electric voltage,mean-square electric current and mean output power is discussed.Results show that the electromechanical coupling coefficients,random excitation and viscoelastic parameter have a positive effect on the output power of the system.展开更多
In this paper,the approximate Bayesian computation combines the particle swarm optimization and se-quential Monte Carlo methods,which identify the parameters of the Mathieu-van der Pol-Duffing chaotic energy harvester...In this paper,the approximate Bayesian computation combines the particle swarm optimization and se-quential Monte Carlo methods,which identify the parameters of the Mathieu-van der Pol-Duffing chaotic energy harvester system.Then the proposed method is applied to estimate the coefficients of the chaotic model and the response output paths of the identified coefficients compared with the observed,which verifies the effectiveness of the proposed method.Finally,a partial response sample of the regular and chaotic responses,determined by the maximum Lyapunov exponent,is applied to detect whether chaotic motion occurs in them by a 0-1 test.This paper can provide a reference for data-based parameter iden-tification and chaotic prediction of chaotic vibration energy harvester systems.展开更多
Over the past few decades,wireless sensor networks have been widely used in the field of structure health monitoring of civil,mechanical,and aerospace systems.Currently,most wireless sensor networks are battery-powere...Over the past few decades,wireless sensor networks have been widely used in the field of structure health monitoring of civil,mechanical,and aerospace systems.Currently,most wireless sensor networks are battery-powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements.As an attempt to address such issue,this article theoretically and experimentally studies a compression-based piezoelectric energy harvester using a multilayer stack configuration,which is suitable for civil infrastructure system applications where large compressive loads occur,such as heavily vehicular loading acting on pavements.In this article,we firstly present analytical and numerical modeling of the piezoelectric multilayer stack under axial compressive loading,which is based on the linear theory of piezoelectricity.A two-degree-of-freedom electromechanical model,considering both the mechanical and electrical aspects of the proposed harvester,was developed to characterize the harvested electrical power under the external electrical load.Exact closed-form expressions of the electromechanical models have been derived to analyze the mechanical and electrical properties of the proposed harvester.The theoretical analyses are validated through several experiments for a test prototype under harmonic excitations.The test results exhibit very good agreement with the analytical analyses and numerical simulations for a range of resistive loads and input excitation levels.展开更多
An enormous number of wireless sensing nodes(WSNs)are of great significance for the Internet of Things(IoT).It is tremendously prospective to realize the in-situ power supply of WSNs by harvesting unutilized mechanica...An enormous number of wireless sensing nodes(WSNs)are of great significance for the Internet of Things(IoT).It is tremendously prospective to realize the in-situ power supply of WSNs by harvesting unutilized mechanical vibration energy.A harmonic silicone rubber triboelectric nanogenerator(HSR-TENG)is developed focusing on ubiquitous constant working frequency machinery.The unique design of the strip serving as a flexible resonator realizes both soft contact and high and broadband output.The significant factors influencing the 1^(st)-order vibration mode of the strip are developed for realizing the harmonic frequency adaptation to external vibration.The surface treatment of the strip improves the output performance of HSR-TENG by 49.1%as well as eliminates the adhesion effect.The HSR-TENG is able to achieve a voltage output bandwidth of 19 Hz under a vibration strength of 3.0,showing its broadband capability.The peak power density of 153.9 W/m^(3)is achieved and 12×0.5 W light-emitting diodes(LEDs)are successfully illuminated by the HSR-TENG.It can continuously power a temperature sensor by harvesting the actual compressor vibration energy.In brief,the HSR-TENG provides a promising way for constant frequency vibration energy harvesting,so as to achieve in-situ power supply for the WSNs in the vicinity.展开更多
Following the current rapid development of the Internet of Things(IoT)and wireless condition monitoring systems,energy harvesters which use ambient energy have become a key part of achieving an energy-autonomous syste...Following the current rapid development of the Internet of Things(IoT)and wireless condition monitoring systems,energy harvesters which use ambient energy have become a key part of achieving an energy-autonomous system.Miniature wind energy harvesters have attracted widespread attention because of their great potential of power density as well as the rich availability of wind energy in many possible areas of application.This article provides readers with a glimpse into the state-of-the-art of miniature wind energy harvesters.The crucial factors for them to achieve high working efficiency under lower operational wind speed excitation are analyzed.Various potential energy coupling mechanisms are discussed in detail.Design approaches for broadening operational wind-speed-range given a variety of energy coupling mechanisms are also presented,as observed in the literature.Performance enhancement mechanisms including hydrodynamic configuration optimization,and non-linear vibration pick-up structure are reviewed.Conclusions are drawn and the outlook for each coupling mechanisms is presented.展开更多
A vibration-based energy harvester is essentially a resonator working in a limited frequency range.To increase the working frequency range is a challenging problem.This paper reveals a novel possibility for enhancing ...A vibration-based energy harvester is essentially a resonator working in a limited frequency range.To increase the working frequency range is a challenging problem.This paper reveals a novel possibility for enhancing energy harvesting via internal resonance.An internal resonance energy harvester is proposed.The excitation is successively assumed as the Gaussian white noise,the colored noise defined by a second-order filter,the narrow-band noise,and exponentially correlated noise.The corresponding averaged root-meansquare output voltages are computed.Numerical results demonstrate that the internal resonance increases the operating bandwidth and the output voltage.展开更多
Ferrofluids are a type of nanometer-scale functional material with fluidity and superparamagnetism.They are composed of ferromagnetic particles,surfactants,and base liquids.The main characteristics of ferrofluids incl...Ferrofluids are a type of nanometer-scale functional material with fluidity and superparamagnetism.They are composed of ferromagnetic particles,surfactants,and base liquids.The main characteristics of ferrofluids include magnetization,the magnetoviscous effect,and levitation characteristics.There are many mature commercial ferrofluid damping applications based on these characteristics that are widely used in numerous fields.Furthermore,some ferrofluid damping studies such as those related to vibration energy harvesters and biomedical devices are still in the laboratory stage.This review paper summarizes typical ferrofluid dampers and energy harvesting systems from the 1960s to the present,including ferrofluid viscous dampers,ferrofluid inertia dampers,tuned magnetic fluid dampers(TMFDs),and vibration energy harvesters.In particular,it focuses on TMFDs and vibration energy harvesters because they have been the hottest research topics in the ferrofluid damping field in recent years.This review also proposes a novel magnetic fluid damper that achieves energy conversion and improves the efficiency of vibration attenuation.Finally,we discuss the potential challenges and development of ferrofluid damping in future research.展开更多
As two crucial indicators of bistable energy harvesting performance,band width and power amplitude are simultaneously investigated for obtaining the synergy effect.Toward this goal,a nonlinear electromechanical-couple...As two crucial indicators of bistable energy harvesting performance,band width and power amplitude are simultaneously investigated for obtaining the synergy effect.Toward this goal,a nonlinear electromechanical-coupled distributed-parameter model of the bistable piezoelectric energy harvester is established.Based on the electromechanical decoupled method,approximate higher-order analytical solutions of the beam displacement,harvested power and effective bandwidth are derived.The cubic-function discriminant of the analytical solution is introduced to determine the nonlinear excitation-frequency boundaries of multiple solutions and power peak.The stability of the multiple solutions is analyzed through Jacobi matrix of the modulation equation.Superharmonic resonance is notified.Upward and downward sweep experiments and numerical solutions of time history curves,phase portraits and power spectra confirm the analytical findings.To realize optimized broadband energy harvesting,the parametric study on the coefficients of the linear and cubic elastic external forces with the corresponding optimal load resistance is performed.For the nonlinear hardening case,more positive linear coefficient is preferred.For the nonlinear softening case,the cubic coefficient slightly larger than its optimal value is recommended at each given linear coefficient.By tuning the load resistance and linear and cubic coefficients of the external force,broadband bistable energy harvesting with optimized power is realized.展开更多
文摘A bimorph piezoelectric beam with periodically variable cross-sections is used for the vibration energy harvesting. The effects of two geometrical parameters on the first band gap of this periodic beam are investigated by the generalized differential quadrature rule (GDQR) method. The GDQR method is also used to calculate the forced vibration response of the beam and voltage of each piezoelectric layer when the beam is subject to a sinusoidal base excitation. Results obtained from the analytical method are compared with those obtained from the finite element simulation with ANSYS, and good agreement is found. The voltage output of this periodic beam over its first band gap is calculated and compared with the voltage output of the uniform piezoelectric beam. It is concluded that this periodic beam has three advantages over the uniform piezoelectric beam, i.e., generating more voltage outputs over a wide frequency range, absorbing vibration, and being less weight.
基金Supported by the National Natural Science Foundation of China(51305183)the Qing Lan Project of Jiangsu Provincethe Doctoral Start-up Foundation of Jinling Institute of Technology(jit-b-201412)
文摘To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments are performed to verify theoretical analysis.When the excitation direction is along Y direction,a maximal output power about 0.139 mW can be harvested at a resistive load of 65kΩ and an excitation frequency of 136 Hz.Theoretical analysis agrees well with experimental results.Furthermore,the performance of multi-direction vibration energy harvester is experimentally tested.The results show that the multi-direction vibration energy harvester can harvest perfect energy as the excitation direction changes in XY plane,YZ plane,XZ plane and body diagonal plane of the harvester.
基金Project supported by the National Natural Science Foundation of China (Nos. 11972051 and11672008)the Opening Project Foundation of the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures (No. KF-2020-11)。
文摘Vibration energy harvesters(VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applications of a micro-electro-mechanical system(MEMS). However, the ambient vibration is always too weak to hinder the high energy conversion efficiency. In this paper, the integrated frame composed of piezoelectric beams and mechanical amplifiers is proposed to improve the energy conversion efficiency of a VEH. First, the initial structures of a piezoelectric frame(PF) and an amplification frame(AF) are designed. The dynamic model is then established to analyze the influence of key structural parameters on the mechanical amplification factor. Finite element simulation is conducted to study the energy harvesting performance, where the stiffness characteristics and power output in the cases of series and parallel load resistance are discussed in detail. Furthermore, piezoelectric beams with variable cross-sections are introduced to optimize and improve the energy harvesting efficiency. Advantages of the PF with the AF are illustrated by comparison with conventional piezoelectric cantilever beams. The results show that the proposed integrated VEH has a good mechanical amplification capability and is more suitable for low-frequency vibration conditions.
文摘Vibration energy harvesting has emerged as a promising method to harvest energy for small-scale applications.Enhancing the performance of a vibration energy harvester(VEH)incorporating nonlinear techniques,for example,the snap-through VEH with geometric non-linearity,has gained attention in recent years.A conventional snap-through VEH is a bi-stable system with a time-invariant potential function,which was investigated extensively in the past.In this work,a modified snap-through VEH with a time-varying potential function subject to harmonic and random base excitations is investigated.Modified snap-through VEHs,such as the one considered in this study,are used in wave energy harvesters.However,the studies on their dynamics and energy harvesting under harmonic and random excitations are limited.The dynamics of the modified snap-through VEH is represented by a system of differential algebraic equations(DAEs),and the numerical schemes are proposed for its solutions.Under a harmonic excitation,the system exhibits periodic and chaotic motions,and the energy harvesting is superior compared with the conventional counterpart.The dynamics under a random excitation is investigated by the moment differential method and the numerical scheme based on the modified Euler-Maruyama method.The Fokker-Planck equation representing the dynamics is derived,and the marginal and joint probability density functions(PDFs)are obtained by the Monte Carlo simulation.The study shows that the modified snap-through oscillator based VEH performs better under both harmonic and random excitations.The dynamics of the system under stochastic resonance(SR)is investigated,and performance enhancement is observed.The results from this study will help in the development of adaptive VEH techniques in the future.
文摘We demonstrate a piezoelectric vibration energy harvester with the ZnO piezoelectric film and an improved synchronous electric charge extraction energy harvesting circuit on the basis of the beam-type mechanical structure,especially investigate its output performance in vibration harvesting and ability to generate charges.By establishing the theoretical model for each of vibration and circuit,the numerical results of voltage and power output are obtained.By fabricating the prototype of this harvester,the quality of the sputtered film is explored.Theoretical and experimental analyses are conducted in open-circuit and closed-circuit conditions,where the open-circuit mode refers to the voltage output in relation to the ZnO film and external excitation,and the power output of the closed-circuit mode is relevant to resistance.Experimental findings show good agreement with the theoretical ones,in the output tendency.It is observed that the properties of ZnO film achieve regularly direct proportion to output performance under different excitations.Furthermore,a maximum experimental power output of 4.5 mW in a resistance range of 3 kΩ-8 kΩis achieved by using an improved synchronous electric charge extraction circuit.The result is not only more than three times the power output of classic circuit,but also can broaden the resistance to a large range of 5 kΩunder an identical maximum value of power output.In this study we demonstrate the fundamental mechanism of piezoelectric materials under multiple conditions and take an example to show the methods of fabricating and testing the ZnO film.Furthermore,it may contribute to a novel energy harvesting circuit with high output performance.
基金supported in part by the National Key Research and Development Program of China(Grant No.2019YFE0120300)the National Natural Science Foundation of China(Grant Nos.52175554,62171414,52205608)+1 种基金the Fundamental Research Program of Shanxi Province(Grant No.202103021223201)the Young Top Talent Project of Hebei Provincial Department of Education(Grant No.BJK2023116)。
文摘With the rapid development of microelectronics and flexible electronics technology,self-powered sensors have significant application prospects in human-machine interface systems and Internet of Things.However,piezoelectric-and triboelectricbased sensors have low current output and are easily affected,while electromagnetic-based sensors are difficult to miniaturize.This work proposes a high-density stacked microcoil integrated microminiaturized electromagnetic vibration energy harvester(EVEH).The double-layer high-density microcoil is fabricated on both sides of the flexible polyimide substrate interconnected via the central through-hole.Owing to reduced single coil line width,line spacing,and stacked structure,the number of turns can be substantially enhanced.Moreover,the relative position of the coils and magnet has a considerable influence on the performances;due to the huge change rate in magnetic flux when the coil is placed in the radial direction of the magnet than in the axial direction,the open-circuit voltage in the radial direction is 10 times greater.The microcoil can maintain good performance at high,low temperatures and under bending conditions.When the distance between the ends of the coil changes from 2 to 20 mm in 2 mm steps,the bending angle of the coil changes from 45°to 270°in 45°steps;furthermore,when the coil is exposed to-40and 60℃conditions,the coil resistance is maintained at approximately 447Ω.The peak open-circuit voltage of three-piece microcoils reaches 0.41 V at 4 Hz under 2g,and the output voltage and current increase with an increasing number of stacked layers.These excellent properties indicate that EVEH can be used for self-powered acceleration sensing.The sensitivity is measured to be 0.016 V/(m/s^(2))with a correlation coefficient of 0.979 over the acceleration range of 1–18 m/s^(2).Thus,the developed microminiaturized EVEH has enormous potential for self-powered sensing applications in confined spaces and harsh environments.
基金the National Natural Science Foundation of China(Grant Nos.12002089 and 11902081)the Science and Technology Projects in Guangzhou(Grant Nos.202201010326 and 2023A04J1323)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023A1515010833)。
文摘Because of the increasing demand for electrical energy,vibration energy harvesters(VEHs)that convert vibratory energy into electrical energy are a promising technology.In order to improve the efficiency of harvesting energy from environmental vibration,here we investigate a hybrid VEH.Unlike previous studies,this article analyzes the stochastic responses of the hybrid piezoelectric and electromagnetic energy harvesting system with viscoelastic material under narrow-band(colored)noise.Firstly,a mass-spring-damping system model coupled with piezoelectric and electromagnetic circuits under fundamental acceleration excitation is established,and analytical solutions to the dimensionless equations are derived.Then,the formula of the amplitude-frequency responses in the deterministic case and the first-order and secondorder steady-state moments of the amplitude in the stochastic case are obtained by using the multi-scales method.The amplitude-frequency analytical solutions are in good agreement with the numerical solutions obtained by the Monte Carlo method.Furthermore,the stochastic bifurcation diagram is plotted for the first-order steady-state moment of the amplitude with respect to the detuning frequency and viscoelastic parameter.Eventually,the influence of system parameters on mean-square electric voltage,mean-square electric current and mean output power is discussed.Results show that the electromechanical coupling coefficients,random excitation and viscoelastic parameter have a positive effect on the output power of the system.
基金This work is supported by the National Nature Science Founda-tion of China(Nos.11972019 and 12102237).
文摘In this paper,the approximate Bayesian computation combines the particle swarm optimization and se-quential Monte Carlo methods,which identify the parameters of the Mathieu-van der Pol-Duffing chaotic energy harvester system.Then the proposed method is applied to estimate the coefficients of the chaotic model and the response output paths of the identified coefficients compared with the observed,which verifies the effectiveness of the proposed method.Finally,a partial response sample of the regular and chaotic responses,determined by the maximum Lyapunov exponent,is applied to detect whether chaotic motion occurs in them by a 0-1 test.This paper can provide a reference for data-based parameter iden-tification and chaotic prediction of chaotic vibration energy harvester systems.
基金supported by the National Science Foundation of China under Grand 51175265.
文摘Over the past few decades,wireless sensor networks have been widely used in the field of structure health monitoring of civil,mechanical,and aerospace systems.Currently,most wireless sensor networks are battery-powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements.As an attempt to address such issue,this article theoretically and experimentally studies a compression-based piezoelectric energy harvester using a multilayer stack configuration,which is suitable for civil infrastructure system applications where large compressive loads occur,such as heavily vehicular loading acting on pavements.In this article,we firstly present analytical and numerical modeling of the piezoelectric multilayer stack under axial compressive loading,which is based on the linear theory of piezoelectricity.A two-degree-of-freedom electromechanical model,considering both the mechanical and electrical aspects of the proposed harvester,was developed to characterize the harvested electrical power under the external electrical load.Exact closed-form expressions of the electromechanical models have been derived to analyze the mechanical and electrical properties of the proposed harvester.The theoretical analyses are validated through several experiments for a test prototype under harmonic excitations.The test results exhibit very good agreement with the analytical analyses and numerical simulations for a range of resistive loads and input excitation levels.
基金supported by the National Natural Science Foundation of China(Nos.52101345,52101400)the Scientific Research Fund of Liaoning Provincial Education Department(No.LJKZ0055)+1 种基金the Dalian Outstanding Young Scientific and Technological Talents Project(No.2021RJ11)the Open Fund of National Center for International Research of Subsea Engineering Technology and Equipment(No.3132023354).
文摘An enormous number of wireless sensing nodes(WSNs)are of great significance for the Internet of Things(IoT).It is tremendously prospective to realize the in-situ power supply of WSNs by harvesting unutilized mechanical vibration energy.A harmonic silicone rubber triboelectric nanogenerator(HSR-TENG)is developed focusing on ubiquitous constant working frequency machinery.The unique design of the strip serving as a flexible resonator realizes both soft contact and high and broadband output.The significant factors influencing the 1^(st)-order vibration mode of the strip are developed for realizing the harmonic frequency adaptation to external vibration.The surface treatment of the strip improves the output performance of HSR-TENG by 49.1%as well as eliminates the adhesion effect.The HSR-TENG is able to achieve a voltage output bandwidth of 19 Hz under a vibration strength of 3.0,showing its broadband capability.The peak power density of 153.9 W/m^(3)is achieved and 12×0.5 W light-emitting diodes(LEDs)are successfully illuminated by the HSR-TENG.It can continuously power a temperature sensor by harvesting the actual compressor vibration energy.In brief,the HSR-TENG provides a promising way for constant frequency vibration energy harvesting,so as to achieve in-situ power supply for the WSNs in the vicinity.
基金the financial support from National Natural Science Foundation of China Grant No.61604023National Natural Science Foundation of China(Grant No.61804016)。
文摘Following the current rapid development of the Internet of Things(IoT)and wireless condition monitoring systems,energy harvesters which use ambient energy have become a key part of achieving an energy-autonomous system.Miniature wind energy harvesters have attracted widespread attention because of their great potential of power density as well as the rich availability of wind energy in many possible areas of application.This article provides readers with a glimpse into the state-of-the-art of miniature wind energy harvesters.The crucial factors for them to achieve high working efficiency under lower operational wind speed excitation are analyzed.Various potential energy coupling mechanisms are discussed in detail.Design approaches for broadening operational wind-speed-range given a variety of energy coupling mechanisms are also presented,as observed in the literature.Performance enhancement mechanisms including hydrodynamic configuration optimization,and non-linear vibration pick-up structure are reviewed.Conclusions are drawn and the outlook for each coupling mechanisms is presented.
基金supported by the State Key Program of National Natural Science of China(Grant No.11232009)Shanghai Leading Academic Discipline Project(Grant No.S30106)
文摘A vibration-based energy harvester is essentially a resonator working in a limited frequency range.To increase the working frequency range is a challenging problem.This paper reveals a novel possibility for enhancing energy harvesting via internal resonance.An internal resonance energy harvester is proposed.The excitation is successively assumed as the Gaussian white noise,the colored noise defined by a second-order filter,the narrow-band noise,and exponentially correlated noise.The corresponding averaged root-meansquare output voltages are computed.Numerical results demonstrate that the internal resonance increases the operating bandwidth and the output voltage.
基金the National Natural Science Foundation of China(Grant Nos.51735006,51927810,and U1837206)Beijing Municipal Natural Science Foundation(Grant No.3182013)。
文摘Ferrofluids are a type of nanometer-scale functional material with fluidity and superparamagnetism.They are composed of ferromagnetic particles,surfactants,and base liquids.The main characteristics of ferrofluids include magnetization,the magnetoviscous effect,and levitation characteristics.There are many mature commercial ferrofluid damping applications based on these characteristics that are widely used in numerous fields.Furthermore,some ferrofluid damping studies such as those related to vibration energy harvesters and biomedical devices are still in the laboratory stage.This review paper summarizes typical ferrofluid dampers and energy harvesting systems from the 1960s to the present,including ferrofluid viscous dampers,ferrofluid inertia dampers,tuned magnetic fluid dampers(TMFDs),and vibration energy harvesters.In particular,it focuses on TMFDs and vibration energy harvesters because they have been the hottest research topics in the ferrofluid damping field in recent years.This review also proposes a novel magnetic fluid damper that achieves energy conversion and improves the efficiency of vibration attenuation.Finally,we discuss the potential challenges and development of ferrofluid damping in future research.
基金supported by National Natural Science Foundation of China(Grants 11802071,11902193,and 11625208)Natural Science Foundation of Shanghai(Grant 19ZR1424300).
文摘As two crucial indicators of bistable energy harvesting performance,band width and power amplitude are simultaneously investigated for obtaining the synergy effect.Toward this goal,a nonlinear electromechanical-coupled distributed-parameter model of the bistable piezoelectric energy harvester is established.Based on the electromechanical decoupled method,approximate higher-order analytical solutions of the beam displacement,harvested power and effective bandwidth are derived.The cubic-function discriminant of the analytical solution is introduced to determine the nonlinear excitation-frequency boundaries of multiple solutions and power peak.The stability of the multiple solutions is analyzed through Jacobi matrix of the modulation equation.Superharmonic resonance is notified.Upward and downward sweep experiments and numerical solutions of time history curves,phase portraits and power spectra confirm the analytical findings.To realize optimized broadband energy harvesting,the parametric study on the coefficients of the linear and cubic elastic external forces with the corresponding optimal load resistance is performed.For the nonlinear hardening case,more positive linear coefficient is preferred.For the nonlinear softening case,the cubic coefficient slightly larger than its optimal value is recommended at each given linear coefficient.By tuning the load resistance and linear and cubic coefficients of the external force,broadband bistable energy harvesting with optimized power is realized.