Exploiting Nonlinearity to Provide Broadband Energy Harvesting

Author(s):  
Jeff Moehlis ◽  
Barry E. DeMartini ◽  
Jeffrey L. Rogers ◽  
Kimberly L. Turner

Energy harvesters are a promising technology for capturing useful energy from the environment or a machine’s operation. In this paper we highlight ideas that might lead to energy harvesters that more efficiently harvest a portion of the considerable vibrational energy that is present for human-made devices and environments such as automobiles, trains, aircraft, watercraft, machinery, and buildings. Specifically, we consider how to exploit ideas based on properties of nonlinear oscillators with negative linear stiffness driven by periodic and stochastic inputs to design energy harvesters having large amplitude response over a broad range of ambient vibration frequencies. Such harvesters could improve upon proposed harvesters of vibrational energy based on linear mechanical principles, which only give appreciable response if the dominant ambient vibration frequency is close to the resonance frequency of the harvester.

Author(s):  
Virgilio J Caetano ◽  
Marcelo A Savi

Energy harvesting from ambient vibration through piezoelectric devices has received a lot of attention in recent years from both academia and industry. One of the main challenges is to develop devices capable of adapting to diverse sources of environmental excitation, being able to efficiently operate over a broadband frequency spectrum. This work proposes a novel multimodal design of a piezoelectric energy harvesting system to harness energy from a wideband ambient vibration source. Circular-shaped and pizza-shaped designs are employed as candidates for the device, comparing their performance with classical beam-shaped devices. Finite element analysis is employed to model system dynamics using ANSYS Workbench. An optimization procedure is applied to the system aiming to seek a configuration that can extract energy from a broader frequency spectrum and maximize its output power. A comparative analysis with conventional energy harvesting systems is performed. Numerical simulations are carried out to investigate the harvester performances under harmonic and random excitations. Results show that the proposed multimodal harvester has potential to harness energy from broadband ambient vibration sources presenting performance advantages in comparison to conventional single-mode energy harvesters.


Author(s):  
Andres F. Arrieta ◽  
Tommaso Delpero ◽  
Paolo Ermanni

Vibration based energy harvesting has received extensive attention in the engineering community for the past decade thanks to its potential for autonomous powering small electronic devices. For this purpose, linear electromechanical devices converting mechanical to useful electrical energy have been extensively investigated. Such systems operate optimally when excited close to or at resonance, however, for these lightly damped structures small variations in the ambient vibration frequency results in a rapid reduction of performance. The idea to use nonlinearity to obtain large amplitude response in a wider frequency range, has shown the potential for achieving so called broadband energy harvesting. An interesting type of nonlinear structures exhibiting the desired broadband response characteristics are bi-stable composites. The bi-stable nature of these composites allows for designing several ranges of wide band large amplitude oscillations, from which high power can be harvested. In this paper, an analytical electromechanical model of cantilevered piezoelectric bi-stable composites for broadband harvesting is presented. The model allows to calculate the modal characteristics, such as natural frequencies and mode shapes, providing a tool for the design of bi-stable composites as harvesting devices. The generalised coupling coefficient is used to select the positioning of piezoelectric elements on the composites for maximising the conversion energy. The modal response of a test specimen is obtained and compared to theoretical results showing good agreement, thus validating the model.


Author(s):  
Wei Wang ◽  
Junyi Cao ◽  
Shengxi Zhou ◽  
Jing Lin

Recently, the power supply for portable electronic devices using the electricity extracted from human motion and ambient vibrations has received considerable attention from multidiscipline field. Among many energy converting mechanisms, the ease miniaturization of piezoelectric cantilever structure propels many research groups to investigate the potential of efficient energy harvesting from ambient vibration using resonant phenomena. However, the incapability of traditional linear energy harvesting from low frequency or varying frequency vibrations has become an open issue. This paper investigates the feasibility of nonlinear energy harvesters with different bistable potential well functions in harvesting energy from walking and running vibration. The portable nonlinear energy harvesting device and its measurement system has been established to obtain the model parameter and excitation signal from human motion. The electromechanical model for bistable energy harvesters with different nonlinear restoring force is derived from theoretical method and experimental data. Numerical investigation under human walking and running vibrations shows that large amplitude interwell motion are easily achieved to improve energy output while the proper potential well function of bistable oscillators is designed. The comparative experiments for nonlinear energy devices with different potential well function are performed. The history and frequency spectrum of output voltage demonstrate the effectiveness of numerical simulation and the clear potential of bistable energy harvesting from human motion by means of appropriate potential function design.


Author(s):  
Aneesh Koka ◽  
Henry A. Sodano

Piezoelectric nanowires (NWs) have recently attracted immense interest due to their excellent electro-mechanical coupling behavior that can efficiently enable conversion of low-intensity mechanical vibrations for powering or augmenting batteries of biomedical devices and portable consumer electronics. Specifically, nano-electromechanical systems (NEMS) composed of piezoelectric NWs offer an exciting potential for energy harvesting applications due to their enhanced flexibility, light weight, and compact size. Compared to the bulk form, high aspect ratio NWs can exhibit higher deformation to produce an enhanced piezoelectric response at a lower stress level. NEMS made of conventional semiconducting vertically aligned, ZnO NW arrays have been investigated thoroughly for energy harvesting; however, ZnO has a lower piezoelectric coupling coefficient as compared to many ferroelectric ceramics which limits its piezoelectric performance. Amidst lead-free ferroelectric materials, environmentally-friendly barium titanate (BaTiO3) possesses one of the highest piezoelectric strain coefficients and thus can enable greater energy transfer when used in vibrational energy harvesters. In this paper, a novel NEMS energy harvester is fabricated using ultra-long (∼40 μm long), vertically aligned BaTiO3 NW arrays which has a low resonant frequency (below 200 Hz) and its AC power harvesting capacity from low amplitude base vibrations (0.25 g) is demonstrated. The design and fabrication of low resonant frequency vibrational energy harvesters has been challenging in the field of MEMS/NEMS since the high stiffness of the structures results in resonant frequency often greater than 1 kHz. However, ambient mechanical vibrations usually exist in the 1 Hz to 1 kHz range and thus highly complaint ultra-long, NW arrays are beneficial to enable efficient energy conversion. Through the use of this newly developed synthesis process for the growth of highly compliant, ultra-long BaTiO3 NW arrays, it is shown that piezoelectric NWs based NEMS energy harvesters capable of harnessing this low frequency ambient vibrational energy can be conceived.


Author(s):  
S. D. Hu ◽  
H. Li ◽  
H. S. Tzou

Piezoelectric materials can be used as electromechanical conversion mechanisms to transfer ambient vibration into electrical energy to power electronic devices. In this study, an elastic ring laminated with a piezoelectric layer on the inner surface is utilized as the basic structure for energy harvesting. The piezoelectric layer is uniformly segmented into several energy harvesting patches for practical applications. The generated electrical energy resulting from modal voltages is analyzed under the open-circuit condition. Two modal energy generations are evaluated: one is the energy induced by the membrane oscillation and the other is the energy induced by the bending oscillation. For practical design applications, energy generations are evaluated with respect to ring radius, piezoelectric layer thickness, ring thickness and segment size. The maximal energy of all harvester patches on the ring is calculated to determine the optimal patch locations with respect to various ring modes. By summing up energies generated from all harvesters on the ring, the overall energy is also evaluated Based on the normalizations and assumptions of parameters, results indicate that the larger the segment size is, the less the energy can be generated.


2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Daniel Geiyer ◽  
Jeffrey L. Kauffman

Component miniaturization and reduced power requirements in sensors have enabled growth in the field of low-power ambient vibration energy harvesting. This work aims to increase bandwidth and power output beyond current techniques by inducing chaotic nonlinear phenomena and applying a low-power controller based on the method of Ott, Grebogi, and Yorke (OGY) to stabilize a chosen periodic orbit. Previously, researchers used a nonlinear piezomagnetoelastic beam in search of a large amplitude broadband voltage response, but chaos was strictly avoided. These large amplitude responses can deteriorate over time into low energy chaotic oscillations. Including chaos as a desirable property allows small perturbations to alter the behavior of a system dramatically, improving the dynamic response for energy harvesting. The nonlinear piezomagnetoelastic beam element described by a Duffing oscillator is extended to embrace chaotic motion more actively. By driving motion along a chaotic attractor, even single frequency excitation results in a theoretically infinite number of unstable periodic orbits that can be stabilized using small control inputs. The chosen orbit will be accessible from a large range of excitation frequencies and can be dynamically changed in real-time, potentially expanding the bandwidth of operation.


Author(s):  
Zahra Sotoudeh

Aeroelastic instabilities such as flutter, limit cycle oscillation (LCO), and divergence are traditionally considered undesirable. Designers try to avoid these instabilities by adding enough stiffness or damping to structures. A new approach to suppressing these instabilities is to use smart material to harvest energy from airflow. In this way not only are the aeroelastic instabilities avoided, but also some energy will be harvested. The harvested energy can be used for powering sensors, morphing parts of the structure, and ultimately increasing the performance of the aircraft. Energy harvesting from aeroelastic phenomena can also be used in designing small wind energy harvesters for home use. In this paper we will explore both capabilities. Piezoelectric materials are among the attractive smart materials for energy harvesting. Piezoelectric materials generate electric potential as they deform. We will explore the use of these materials in aeroelastic harvesting. Ref. 1 has a general overview of different forms of vibrational energy harvesting, including the use of piezoelectric materials. Harvesting energy from aeroelastic instabilities is a relatively new area; therefore, the body of literature on this subject is relatively young. Most of the analysis is limited to a 2-D cross-sectional analysis with steady or quasi-steady flow. We will use a 2-D model with an unsteady aerodynamic model as the preliminary result. More realistic cases with a beam model will be added to the final version of the paper. For the beam model, we will use fully intrinsic equations.


Author(s):  
Wei Wang ◽  
Junyi Cao ◽  
Ying Zhang ◽  
Chris R. Bowen

In recent decades, the technique of piezoelectric energy harvesting has drawn a great deal of attention since it is a promising method to convert vibrational energy to electrical energy to supply lower-electrical power consumption devices. The most commonly used configuration for energy harvesting is the piezoelectric cantilever beam. Due to the inability of linear energy harvesting to capture broadband vibrations, most researchers have been focusing on broadband performance enhancement by introducing nonlinear phenomena into the harvesting systems. Previous studies have often focused on the symmetric potential harvesters excited in a fixed direction and the influence of the gravity of the oscillators was neglected. However, it is difficult to attain a completely symmetric energy harvester in practice. Furthermore, the gravity of the oscillator due to the change of installation angle will also exert a dramatic influence on the power output. Therefore, this paper experimentally investigates the influence of gravity due to bias angle on the output performance of asymmetric potential energy harvesters under harmonic excitation. An experimental system is developed to measure the output voltages of the harvesters at different bias angles. Experimental results show that the bias angle has little influence on the performance of linear and monostable energy harvesters. However, for an asymmetric potential bistable harvester with sensitive nonlinear restoring forces, the bias angle influences the power output greatly due to the effect of gravity. There exists an optimum bias angle range for the asymmetric potential bistable harvester to generate large output power in a broader frequency range. The reason for this phenomenon is that the influence of gravity due to bias angle will balance the nonlinear asymmetric potential function in a certain range, which could be applied to improve the power output of asymmetric bistable harvesters.


Author(s):  
Reza Madankan ◽  
M. Amin Karami ◽  
Puneet Singla

This paper presents the relation between uncertainty in the excitation and parameters of vibrational energy harvesting systems and their power output. Nonlinear vibrational energy harvesters are very sensitive to the frequency of the base excitation. If the excitation frequency does not match with the resonance frequency of the energy harvester, the power output significantly deteriorates. The mismatch can be due to the inherent changes of the ambient oscillations. The fabrication errors or gradual changes of material properties also result in the mismatch. This paper quantitatively shows the probability density function for the power as a function of the probability densities of the excitation frequency, excitation amplitude, initial deflection of the energy harvester, and design parameters. Recently developed the conjugated unscented transformation methodology is used in conjunction with the principle of maximum entropy to compute the probability distribution for the base response and power. The computed nonlinear density functions are validated against Monte Carlo simulations.


Author(s):  
Dongxu Su ◽  
Kimihiko Nakano ◽  
Honggang Hu ◽  
Matthew P. Cartmell ◽  
Masanori Ohori ◽  
...  

In addition to the wide range of applications of stochastic resonance in the field of signal processing, the phenomenon has also been investigated as an effective tool for enhancing vibrational energy harvesting. This paper proposes a hypothetical method for achieving stochastic resonance and increasing the available energy from external ambient vibration. In order to illustrate this proposal, a bistable mechanical system is proposed to study the feasibility by theoretical analysis. The amount of available energy and the energy consumed to produce the small-scale additional force is analyzed through numerical simulations. It is shown that the proposed method can significantly enhance the harvested vibrational energy.


Sign in / Sign up

Export Citation Format

Share Document