Energy Harvesting Using a Torsional Mode L-Shaped Unimorph Structure: Modeling and Experimental Investigations

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Haisheng Li ◽  
Donghuan Liu ◽  
Jianjun Wang ◽  
Xinchun Shang
Keyword(s):  
Energy Harvesting ◽  
Electromechanical Coupling ◽  
Mechanical Vibration ◽  
Beam Theory ◽  
Experimental Investigations ◽  
Base Excitation ◽  
Torsional Mode ◽  
Plane Base ◽  
Bending Mode ◽  
Out Of Plane

Abstract Previous studies have proved that the piezoelectric L-shaped beam-mass structure is a good candidate to harvest energy from ambient mechanical vibration. However, most researches merely focused on bending mode of the structure, which only can capture energy from in-plane base excitation. To fully exert the advantages of L-shaped harvesters, this paper will explore their energy harvesting performance on torsional mode with out-of-plane base excitation. The electromechanical coupling governing equation of the L-shaped harvester in torsional mode is derived by applying Gauss's law and the Euler–Bernoulli beam theory with linear assumption, and the analytical results are also validated with experimental results. In addition, the influences of key geometric parameters on the resonance frequency and output voltage of the harvester are also presented. This work demonstrates the feasibility of utilizing torsional mode of the L-shaped unimorph structure to harvest energy from out-of-plane mechanical vibration, which shows the potential of designing multi-directional and multi-frequency L-shaped harvesters.

scholarly journals Piezoelectric Particulate Composite for Energy Harvesting from Mechanical Vibration

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4925
Author(s):  
Dariusz Grzybek ◽  
Dariusz Kata ◽  
Wojciech Sikora ◽  
Bogdan Sapiński ◽  
Piotr Micek ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Rectangular Cross Section ◽  
Mechanical Vibration ◽  
Electric Energy ◽  
Particulate Composite ◽  
Piezoelectric Composite ◽  
Main Element ◽  
Beam Structure ◽  
Bending Mode ◽  
The Subject

Energy harvesting from mechanical vibration of buildings is usually realized by the use of devices, in which the main element is a prismatic beam with a rectangular cross-section. The beam has been the subject of scientific research; it is usually constructed with a carrying substrate that does not have piezoelectric characteristics and from piezoelectric material. In contrast, this investigation sought to create a beam structure with a piezoelectric composite only. The entire beam structure was made of a prototype piezoelectric particulate composite. Based on courses of voltage obtained in laboratory experiments and known geometry of the specimens, a series of finite element method (FEM) simulations was performed, aiming to estimate the piezoelectric coefficient d31 value at which the mentioned voltage could be achieved. In each specimen, sedimentation caused the formation of two distinct layers: top and bottom. The experiments revealed that the presented prototype piezoelectric particulate composite converts mechanical stress to electric energy in bending mode, which is used in energy harvesting from mechanical vibration. It is self-supporting and thus a carrying substrate is not required in the harvester structure.

scholarly journals Theoretical and Experimental Investigations of a Pseudo-Magnetic Levitation System for Energy Harvesting

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1623
Author(s):  
Krzysztof Kecik ◽  
Andrzej Mitura
Keyword(s):  
Energy Harvesting ◽  
Electromechanical Coupling ◽  
Magnetic Levitation ◽  
Continuation Method ◽  
Harmonic Balance Method ◽  
Path Following ◽  
Experimental Investigations ◽  
System Response ◽  
Electrical Systems ◽  
Magnetic Levitation System

The paper presents an analytical, numerical and experimental analysis of the special designed system for energy harvesting. The harvester system consists of two identical magnets rigidly mounted to the tube’s end. Between them, a third magnet is free to magnetically levitate (pseudo-levitate) due to the proper magnet polarity. The behaviour of the harvester is significantly complicated by a electromechanical coupling. It causes resonance curves to have a distorted shape and a new solution from which the recovered energy is higher is observed. The Harmonic Balance Method (HBM) is used to approximately describe the response and stability of the mechanical and electrical systems. The analytical results are verified by a numerical path following (continuation) method and experiment test with use of a shaker. The influence of harvester parameters on the system response and energy recovery near a main resonance is studied in detail.

scholarly journals The conformational changes accompanying the triplet–singlet electronic excitation of acetaldehyde, CH3CHO

1985 ◽  
Vol 63 (7) ◽  
pp. 1378-1381 ◽  
Author(s):  
D. C. Moule ◽  
K. H. K. Ng
Keyword(s):  
Conformational Changes ◽  
Room Temperature ◽  
Electronic Excitation ◽  
Vapour Phase ◽  
Torsional Mode ◽  
Methyl Group ◽  
Bending Mode ◽  
Out Of Plane ◽  
The Many ◽  
Franck Condon

The first electronic absorption system of acetaldehyde was recorded in the vapour phase at room temperature. The many-banded spectrum proved to be very complex and it was only at the extreme red edge of the absorption that the pattern became simple enough to analyze. The major experimental requirement was a high pressure × path length (500 Torr × 168 m). Spectra were interpreted in terms of the torsional mode ν′15 and ν″15 attached to the ν′14 out-of-plane bending mode. Both modes were highly Franck–Condon active and the [Formula: see text] band at 27240.4 cm−1 was not directly observed. The barrier to rotation of the methyl group was 618.5 cm−1. More surprising was the observation that the methyl group undergoes a rotation from a [Formula: see text] eclipsed configuration to a staggered configuration. The intensity of the ν′14 quantum addition and its position in the spectrum suggest that the aldehydic hydrogen is nonplanar in the ã state.

Vibration Modeling of Arc-Based Cantilevers for Energy Harvesting Applications

2014 ◽  
Vol 1 (1-2) ◽  
Author(s):  
Daniel J. Apo ◽  
Mohan Sanghadasa ◽  
Shashank Priya
Keyword(s):  
Energy Harvesting ◽  
Low Frequency ◽  
Substrate Thickness ◽  
Cantilever Beams ◽  
Vibration Energy Harvesting ◽  
Low Frequency Vibration ◽  
Vibration Model ◽  
Bending Mode ◽  
Out Of Plane ◽  
Tip Mass

AbstractCantilever beams are widely used for designing transducers for low-frequency vibration energy harvesting. However, in order to keep the dimensions within reasonable constraints, a large tip mass is generally required for reducing the resonance frequency below 100 Hz which has adverse effect on the reliability. This study provides a breakthrough toward realizing low-frequency micro-scale transduction structures. An analytical out-of-plane vibration model for standalone arc-based cantilever beams was developed that includes provisions for shear and rotary inertia, multidirectional arcs, and multiple layers. The model was applied to a multilayered cantilever beam (10-mm wide and 0.1-mm thick) composed of three arcs, and the results indicate that the fundamental bending mode of the beam was 38 Hz for a silicon substrate thickness of 100 μm. The model was validated with modal experimental results from an arc-based cantilever made out of aluminum.

Flexoelectric energy harvesters based on Timoshenko laminated beam theory

2017 ◽  
Vol 28 (15) ◽  
pp. 2064-2073 ◽  
Author(s):  
Xu Liang ◽  
Runzhi Zhang ◽  
Shuling Hu ◽  
Shengping Shen
Keyword(s):  
Resonance Frequency ◽  
Energy Conversion ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Mechanical Energy ◽  
Mechanical Vibration ◽  
Beam Theory ◽  
Electrical Energy ◽  
Laminated Beam ◽  
Energy Harvesters

Different from piezoelectricity which is restricted to certain materials, flexoelectricity is a universal electromechanical coupling in all dielectrics. In this work, mechanical energy harvester models were developed based on Timoshenko laminated beam theory, in which the flexoelectric and piezoelectric mechanisms were discussed. For a three-layered energy harvester in parallel configuration, the mechanical vibration energy can be converted into electrical energy due to flexoelectricity, and for the three-layered energy harvester in series configuration, the energy conversion is enhanced by the flexoelectricity. Resonance frequency shifts were observed in the calculations due to flexoelectricity and external circuit resistance. It is found that the electromechanical coupling displayed from the electrical responses versus resonance frequency and resistance. The energy conversion for the three-layered energy harvester system was found to be increased with the decrease in the laminated beam thickness. The energy conversion calculated for different numbers of layers also indicates that laminated energy harvester systems excel single-layered energy harvesters. This work therefore might help in designing flexoelectricity-based energy harvesters.

Numerical analysis of nonlinear functionally graded piezoelectric energy harvester subjected to multi moving oscillators

2021 ◽  
pp. 095440622110036
Author(s):  
P Fatehi ◽  
M Mahzoon ◽  
M Farid
Keyword(s):  
Energy Harvesting ◽  
Nonlinear Vibration ◽  
Electromechanical Coupling ◽  
Damping Ratio ◽  
Beam Theory ◽  
Functionally Graded ◽  
Integration Scheme ◽  
Functionally Graded Beam ◽  
Piezoelectric Patch ◽  
Piezoelectric Energy

In this paper, energy harvesting from nonlinear vibration of a functionally graded beam covered by a piezoelectric patch under multi-moving oscillators is studied. The material of both the substructure and the piezoelectric patch is assumed to be functionally graded in the thickness direction. A coupled system of equations considering Euler-Bernoulli beam theory and von-Karman nonlinearity as well as electromechanical coupling are derived using the generalized Hamilton’s principle. Finite element method as well as Newmark time integration scheme are used to solve the coupled nonlinear time dependent problem. The effects of different parameters including material distribution, velocity of the moving oscillators, piezoelectric patch thickness and load resistance on the output voltage and harvested power are investigated. Moreover, the effects of oscillator characteristics such as damping ratio and stiffness on the nonlinear behavior of the beam and harvested power are also studied. Results indicate that the aforementioned parameters have considerable effects on the harvested power. It is also shown that ignoring nonlinear effects may lead to erroneous and unacceptable results. To the best of authors’ knowledge, there is no study about energy harvesting from nonlinear vibration of beams under moving oscillators.

scholarly journals Microcrack Detection Using Spectral Response Data Alone

2021 ◽  
Vol 11 (8) ◽  
pp. 3655
Author(s):  
Gee-Soo Lee ◽  
Chan-Jung Kim
Keyword(s):  
Spectral Response ◽  
Coherence Function ◽  
Cold Forming ◽  
Response Data ◽  
Highly Sensitive ◽  
Bending Mode ◽  
Out Of Plane ◽  
Rectangular Specimen ◽  
Microcrack Detection ◽  
Impulse Force

Microcracks of depth less than 200 μm in mechanical components are difficult to detect because conventional methods such as X-ray or eddy current measurements are less sensitive to such depths. Nonetheless, an efficient microcrack detection method is required urgently in the mechanical industry because microcracks are produced frequently during cold-forming. The frequency response function (FRF) is known to be highly sensitive even to microcracks, and it can be obtained using both the input data of an impact hammer and the response data of an accelerometer. Under the assumption of an impulse force with a similar spectral impulse pattern, spectral response data alone could be used as a crack indicator because the dynamic characteristics of a microcrack may be dependent solely on these measured data. This study investigates the feasibility of microcrack detection using the response data alone through impact tests with a simple rectangular specimen. A simple rectangular specimen with a 200 μm microcrack at one face was prepared. The experimental modal analysis was conducted for the normal (uncracked) specimen and found-first bending mode about 1090 Hz at the X-Y plane (in-plane). Response accelerations were obtained in both at in-plane locations as well as X-Z plane (out-of-plane), and the crack was detected using the coherence function between a normal and a cracked specimen. A comparison of the crack inspection results obtained using the response data and the FRF data indicated the validity of the proposed method.

Enhanced frequency synchronization for concurrent aeroelastic and base vibratory energy harvesting using a softening nonlinear galloping energy harvester

2021 ◽  
pp. 1045389X2110263
Author(s):  
Shun Chen ◽  
David Eager ◽  
Liya Zhao
Keyword(s):  
Energy Harvesting ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Poor Performance ◽  
Effective Bandwidth ◽  
Frequency Synchronization ◽  
Periodic Oscillations ◽  
Energy Harvesters ◽  
Paper Form ◽  
Excited Oscillation

This paper proposes a softening nonlinear aeroelastic galloping energy harvester for enhanced energy harvesting from concurrent wind flow and base vibration. Traditional linear aeroelastic energy harvesters have poor performance with quasi-periodic oscillations when the base vibration frequency deviates from the aeroelastic frequency. The softening nonlinearity in the proposed harvester alters the self-excited galloping frequency and simultaneously extends the large-amplitude base-excited oscillation to a wider frequency range, achieving frequency synchronization over a remarkably broadened bandwidth with periodic oscillations for efficient energy conversion from dual sources. A fully coupled aero-electro-mechanical model is built and validated with measurements on a devised prototype. At a wind speed of 5.5 m/s and base acceleration of 0.1 g, the proposed harvester improves the performance by widening the effective bandwidth by 300% compared to the linear counterpart without sacrificing the voltage level. The influences of nonlinearity configuration, excitation magnitude, and electromechanical coupling strength on the mechanical and electrical behavior are examined. The results of this paper form a baseline for future efficiency enhancement of energy harvesting from concurrent wind and base vibration utilizing monostable stiffness nonlinearities.

scholarly journals Parametric Instability of a Traveling Plate Partially Supported by a Laterally Moving Elastic Foundation

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
V. Kartik ◽  
J. A. Wickert
Keyword(s):  
Data Storage ◽  
Parametric Instability ◽  
Primary Resonance ◽  
Free Edge ◽  
Moving Plate ◽  
Torsional Mode ◽  
Plane Vibration ◽  
Out Of Plane ◽  
Axially Moving ◽  
The Stability

The parametric excitation of an axially moving plate is examined in an application where a partial foundation moves in the plane of the plate and in a direction orthogonal to the plate’s transport. The stability of the plate’s out-of-plane vibration is of interest in a magnetic tape data storage application where the read/write head is substantially narrower than the tape’s width and is repositioned during track-following maneuvers. In this case, the model’s equation of motion has time-dependent coefficients, and vibration is excited both parametrically and by direct forcing. The parametric instability of out-of-plane vibration is analyzed by using the Floquet theory for finite values of the foundation’s range of motion. For a relatively soft foundation, vibration is excited preferentially at the primary resonance of the plate’s fundamental torsional mode. As the foundation’s stiffness increases, multiple primary and combination resonances occur, and they dominate the plate’s stability; small islands, however, do exist within unstable zones of the frequency-amplitude parameter space for which vibration is marginally stable. The plate’s and foundation’s geometry, the foundation’s stiffness, and the excitation’s amplitude and frequency can be selected in order to reduce undesirable vibration that occurs along the plate’s free edge.

Modeling and Experimental Validations of a Piezoelectric Energy Harvester Under Combined Galloping and Base Excitations

2014 ◽  
Author(s):  
Amin Bibo ◽  
Abdessattar Abdelkefi ◽  
Mohammed F. Daqaq
Keyword(s):  
Bluff Body ◽  
Energy Harvester ◽  
Constitutive Relations ◽  
Excitation Frequency ◽  
Primary Resonance ◽  
Beam Theory ◽  
Excitation Amplitude ◽  
The Body ◽  
Base Excitation ◽  
Piezoelectric Energy

This paper develops an experimentally validated model of a piezoelectric energy harvester under combined aeroelastic-galloping and base excitations. To that end, an energy harvester consisting of a thin piezoelectric cantilever beam subjected to vibratory base excitation is considered. To permit galloping excitation, a bluff body is rigidly attached at the free end such that a net aerodynamic lift is generated as the incoming airflow separates on both sides of the body giving rise to limit cycle oscillations when the flow velocity exceeds a critical value. A nonlinear electromechanical distributed-parameter model of the harvester under the combined excitation is derived using the energy approach and by adopting the nonlinear Euler-Bernoulli beam theory, linear constitutive relations for the piezoelectric transduction, and the quasi-steady assumption for the aerodynamic loading. The partial differential equations of the system are discretized and a reduced-order-model is obtained. The mathematical model is validated by conducting a series of experiments with different loading conditions represented by wind speed, base excitation amplitude, and excitation frequency around the primary resonance.

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