The effect of nonlinear material viscosity on the energy harvesting performance of dielectric elastomer generators

2020 ◽  
Vol 31 (7) ◽  
pp. 1029-1038
Author(s):  
Yuanping Li ◽  
Jianyou Zhou ◽  
Liying Jiang
Keyword(s):  
Energy Harvesting ◽  
Conversion Efficiency ◽  
Electromechanical Coupling ◽  
Failure Modes ◽  
Mechanical Energy ◽  
Theoretical Perspective ◽  
Dielectric Elastomer ◽  
Viscosity Model ◽  
Nonlinear Material ◽  
Simulation Results

Dielectric elastomer generators are capable of converting mechanical energy from a variety of sources into electrical energy. The energy harvesting performance depends on the interplay between electromechanical coupling, material viscosity, and multiple failure modes. Experiments also suggest that the material viscosity of dielectric elastomers is deformation-dependent, which makes the prediction of the performance of dielectric elastomer generators more challenging. By adopting the coupled field theory, finite-deformation viscoelasticity theory, and the theory for polymer dynamics, this work investigates the harvested energy and conversion efficiency of dielectric elastomer generators from theoretical perspective. By comparing the simulation results from the nonlinear viscosity model to the experimental data and the simulation results from the linear viscosity model, we further examine the possible factors that may strongly influence the performance of dielectric elastomer generators. It is found that dielectric elastomer generators exhibit higher harvested energy when nonlinear material viscosity is considered. Moreover, by selecting a higher voltage of the power supply for the generator, the conversion efficiency of dielectric elastomer generators can be greatly improved. The theoretical framework in this study is expected to offer some new insights into optimizing the design of dielectric elastomer generators and thus improving their performance.

scholarly journals Optimizing the Energy Harvesting Cycle of a Dissipative Dielectric Elastomer Generator for Performance Improvement

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1341 ◽  
Author(s):  
Peng Fan ◽  
Hualing Chen
Keyword(s):  
Energy Density ◽  
Energy Harvesting ◽  
Time Constant ◽  
Conversion Efficiency ◽  
Dielectric Elastomer ◽  
Enhancement Effect ◽  
The Novel ◽  
Optimal Transfer ◽  
Conversion Performance ◽  
Good Agreement

This paper optimizes the energy harvesting cycle of dissipative dielectric elastomer generators (DEGs) to explore possible approaches for improving the energy harvesting performance. By utilizing the developed theoretical framework, the dissipative performance of the DEG with a constant voltage cycle is analyzed, which shows good agreement with the existing experimental data. On this basis, we design a novel energy harvesting cycle and a corresponding energy harvesting circuit in which a transfer capacitor is utilized to store the charge transferred from the DEG. Then, the energy conversion performance of the DEG with the novel energy harvesting cycle is investigated. The results indicate that both the energy density and conversion efficiency are improved by choosing a high voltage during the discharging process and that as the R-C time constant increases, the enhancement effect of the voltage increases and then approaches to the saturation. In addition, there is an optimal transfer capacitor that can maximize energy density or conversion efficiency, and the optimal transfer capacitor increases with the increase in the R-C time constant. These results and methods are expected to guide the optimal design and assessment of DEGs.

Dielectric Elastomer Energy Harvesting and its Application to Human Walking

2011 ◽  
Author(s):  
Heather Lai ◽  
Chin An Tan ◽  
Yong Xu
Keyword(s):  
Energy Harvesting ◽  
Knee Joint ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Metabolic Energy ◽  
High Energy Density ◽  
Human Walking ◽  
Wide Range

Human walking requires sophisticated coordination of muscles, tendons, and ligaments working together to provide a constantly changing combination of force, stiffness and damping. In particular, the human knee joint acts as a variable damper, dissipating greater amounts of energy when the knee undergoes large rotational displacements during walking, running or hopping. Typically, this damping results from the dissipation, or loss, of metabolic energy. It has been proven to be possible however; to collect this otherwise wasted energy through the use of electromechanical transducers of several different types which convert mechanical energy to electrical energy. When properly controlled, this type of device not only provides desirable structural damping effects, but the energy generated can be stored for use in a wide range of applications. A novel approach to an energy harvesting knee joint damper is presented using a dielectric elastomer (DE) smart material based electromechanical transducer. Dielectric elastomers are extremely elastic materials with high electrical permittivity which operate based on electrostatic effects. By placing compliant electrodes on either side of a dielectric elastomer film, a specialized capacitor is created, which couples mechanical and electrical energy using induced electrostatic stresses. Dielectric elastomer energy harvesting devices not only have a high energy density, but the material properties are similar to that of human tissue, making it highly suitable for wearable applications. A theoretical framework for dielectric elastomer energy harvesting is presented along with a mapping of the active phases of the energy harvesting to the appropriate phases of the walking stride. Experimental results demonstrating the energy harvesting capability of a DE generator undergoing strains similar to those experienced during walking are provided for the purpose of verifying the theoretical results. The work presented here can be applied to devices for use in rehabilitation of patients with muscular dysfunction and transfemoral prosthesis as well as energy generation for able-bodied wearers.

scholarly journals A High-Efficiency Energy Harvesting By Using Hydraulic Electromagnetic Regenerative Shock Absorber

2020 ◽  
Author(s):  
Muhammad Yousaf Iqbal ◽  
Zhifei Wu ◽  
Khalid Mahmood
Keyword(s):  
Mathematical Model ◽  
Energy Harvesting ◽  
Shock Absorber ◽  
Mechanical Energy ◽  
Excitation Frequency ◽  
National Standard ◽  
Damping Force ◽  
Damping Characteristics ◽  
Simulation Results ◽  
Regenerative Shock Absorber

Abstract This article intends a hybrid energy harvesting shock absorber design which comprehends energy harvesting of automobile suspension vibration dissipation. A mathematical model of the energy harvesting prototype is established, and simulation results show that the dissipation energy can be recovered by varying the feed module, thereby got the damping forces ratio at different compression and extension stroke. The energy conversion from hydraulic energy to mechanical energy mainly then mechanical energy converted into electrical energy furthermore we can rechange our battery from this recovered energy. The advanced mathematical model and prototype proposed maximum ride comfort meanwhile recovered the suspension energy and fuel saving. This article shows the simulation results verifying it with prototype test results. The damping force of expansion stroke is higher than the damping force of compression stroke. The damping characteristics curves and speed characteristics curves verify the validity by simulation and prototyping damper at different amplitudes of off-road vehicles. The Hydraulic Electromagnetic Regenerative Shock Absorber (HESA) prototype characteristic is tested in which 65 watts recovered energy at 1.67 Hz excitation frequency. So, 14.65% maximum energy recovery efficiency got at 20 mm rod diameter and 8 cc/rev motor displacement. The damping characteristics of the HESA prototype examined and it has ideal performance as the standard requirements of the National Standard QC/T 491–1999.

Thermodynamic Analysis of a Direct Mechanical to Electrical Energy Harvesting Cycle in Ferroelectric Crystals

2017 ◽  
Author(s):  
John A. Gallagher
Keyword(s):  
Phase Transformation ◽  
Energy Harvesting ◽  
Numerical Integration ◽  
Electromechanical Coupling ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Ferroelectric Crystals ◽  
Mechanical Cycling

Field induced phase transformations in ferroelectric crystals occur when the applied electrical or mechanical load exceeds a certain threshold. Mechanical cycling about these transformation field thresholds under varying open and closed circuit conditions has been shown to yield a near ideal mechanical to electrical energy harvesting technique. Numerical integration of experimentally measured stress – strain and electric field – electric displacement data has shown mechanical to electrical energy conversion efficiency near 60% for 0.24PIN-0.44PMN-0.32PT. In this work, the total irreversible energy is determined by the offset between the forward and reverse loading paths, equivalent to the hysteresis in the phase transformation behavior. This is equal to the available mechanical energy for conversion to electrical energy for harvesting. Following the ideal mechanical to electrical energy harvesting procedure, the total possible energy harvested is a direct function of the hysteresis area in the phase transformation and the electromechanical coupling factor. Efficiency is predicted to be equal to the electromechanical coupling factor, 0.596 (59.6%). Predicted results agree with experimental data from numerical integration. Energy densities are calculated up to 5 kJ/m3 with potential power densities of 102–103 kW/m3.

Investigation on the dynamic performance of viscoelastic dielectric elastomer oscillators considering nonlinear material viscosity

2019 ◽  
Vol 30 (20) ◽  
pp. 3190-3199 ◽  
Author(s):  
Yuanping Li ◽  
Jianyou Zhou ◽  
Liying Jiang
Keyword(s):  
Electromechanical Coupling ◽  
Frequency Tuning ◽  
Dynamic Performance ◽  
Transient State ◽  
Dielectric Elastomer ◽  
Nonlinear Material ◽  
Dielectric Elastomers ◽  
Modeling Framework ◽  
Practical Applications ◽  
External Stimuli

As a typical kind of soft electroactive materials, dielectric elastomers are capable of producing large deformation under external stimuli, which makes them desirable materials for many practical applications in transduction technology, including tunable oscillators and resonators. The dynamic performance of such dielectric elastomer–based vibrational devices is strongly affected by material viscosity as well as electromechanical coupling. Moreover, as suggested by experiments and theoretical studies, dielectric elastomers exhibit deformation-dependent relaxation process, which makes the modeling of the dynamic performance of dielectric elastomer–based devices more challenging. In this work, by adopting the state-of-art modeling framework of finite-deformation viscoelasticity, the effect of the nonlinear material viscosity on the in-plane oscillation and the frequency tuning of dielectric elastomer membrane oscillators is investigated. From the simulation results, it is found that the nonlinear viscosity only affects the transient state of the frequency tuning process. The modeling framework developed in this work is expected to provide useful guidelines for predicting the dynamic performance of dielectric elastomer–based vibrational devices as well as their optimal design.

scholarly journals Geometrical Investigation of Piezoelectric Patches for Broadband Energy Harvesting in Non-Deterministic Composite Plates

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7370
Author(s):  
Asan G. A. Muthalif ◽  
Abdelrahman Ali ◽  
Jamil Renno ◽  
Azni N. Wahid ◽  
Khairul A. M. Nor ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Fiber Orientation ◽  
Electromechanical Coupling ◽  
Mechanical Energy ◽  
Electrical Power ◽  
Electrical Potential ◽  
Composite Plates ◽  
Maximum Energy ◽  
Fe Model ◽  
Piezoelectric Energy

Mechanical energy is the most ubiquitous form of energy that can be harvested and converted into useful electrical power. For this reason, the piezoelectric energy harvesters (PEHs), with their inherent electromechanical coupling and high-power density, have been widely incorporated in many applications to generate power from ambient mechanical vibrations. However, one of the main challenges to the wider adoption of PEHs is how to optimize their design for maximum energy harvesting. In this paper, an investigation was conducted on the energy harvesting from seven piezoelectric patch shapes (differing in the number of edges) when attached to a non-deterministic laminated composite (single/double lamina) plate subjected to change in fiber orientation. The performance of the PEHs was examined through a coupled-field finite element (FE) model. The plate was simply supported, and its dynamics were randomized by attaching randomly distributed point masses on the plate surface in addition to applying randomly located time-harmonic point forces. The randomization of point masses and point force location on a thin plate produce non-deterministic response. The design optimization was performed by employing the ensemble-responses of the electrical potential developed across the electrodes of the piezoelectric patches. The results present the optimal fiber orientation and patch shape for maximum energy harvesting in the case of single and double lamina composite plates. The results show that the performance is optimal at 0° or 90° fiber orientation for single-lamina, and at 0°/0° and 0°/90° fiber orientations for double-lamina composites. For frequencies below 25 Hz, patches with a low number of edges exhibited a higher harvesting performance (triangular for single-lamina/quadrilateral for double-lamina). As for the broadband frequencies (above 25 Hz), the performance was optimal for the patches with a higher number of edges (dodecagonal for single-lamina/octagonal for double-lamina).

scholarly journals Deep Insight into the Influences of the Intrinsic Properties of Dielectric Elastomer on the Energy-Harvesting Performance of the Dielectric Elastomer Generator

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4202
Author(s):  
Yingjie Jiang ◽  
Yujia Li ◽  
Haibo Yang ◽  
Nanying Ning ◽  
Ming Tian ◽  
...  
Keyword(s):  
Energy Density ◽  
Energy Harvesting ◽  
Conversion Efficiency ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Breakdown Field ◽  
Intrinsic Properties ◽  
High Permittivity ◽  
The Relationship

The dielectric elastomer (DE) generator (DEG), which can convert mechanical energy to electrical energy, has attracted considerable attention in the last decade. Currently, the energy-harvesting performances of the DEG still require improvement. One major reason is that the mechanical and electrical properties of DE materials are not well coordinated. To provide guidance for producing high-performance DE materials for the DEG, the relationship between the intrinsic properties of DE materials and the energy-harvesting performances of the DEG must be revealed. In this study, a simplified but validated electromechanical model based on an actual circuit is developed to study the relationship between the intrinsic properties of DE materials and the energy-harvesting performance. Experimental verification of the model is performed, and the results indicate the validity of the proposed model, which can well predict the energy-harvesting performances. The influences of six intrinsic properties of DE materials on energy-harvesting performances is systematically studied. The results indicate that a high breakdown field strength, low conductivity and high elasticity of DE materials are the prerequisites for obtaining high energy density and conversion efficiency. DE materials with high elongation at break, high permittivity and moderate modulus can further improve the energy density and conversion efficiency of the DEG. The ratio of permittivity and the modulus of the DE should be tailored to be moderate to optimize conversion efficiency (η) of the DEG because using DE with high permittivity but extremely low modulus may lead to a reduction in η due to the occurrence of premature “loss of tension”.

An Investigation of Energy Harvesting Using Electrostrictive Polymers

2005 ◽  
Vol 889 ◽  
Author(s):  
Kailiang Ren ◽  
Yiming Liu ◽  
Heath F Hofmann ◽  
Qiming Zhang
Keyword(s):  
Energy Density ◽  
Energy Harvesting ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Electromechanical Coupling ◽  
Electrical Energy ◽  
Energy Conversion Efficiency ◽  
Unique Property ◽  
Elastic Energy Density ◽  
Ac Field

ABSTRACTOwing to their low acoustic impedance, high elastic energy density, and relatively high electromechanical conversion efficiency, the electroactive polymers have begun to show the potential for energy harvesting or mechanical to electrical energy conversion. In addition, due to the electromechanical coupling in these materials the electric and mechanical properties of these polymers will depend on the imposed electrical and mechanical conditions. This paper discusses how to utilizing this unique property to maximum the energy conversion efficiency and the harvested electrical energy density in the electrostrictive polymers. As an example, we demonstrate that when a properly phased and externally applied electric AC field is superimposed on the mechanical cycle, an output electrical energy density of 39mJ/cm3 and mechanical-to-electrical conversion efficiency of about 10% can be obtained from the electrostrictive P(VDF-TrFE) based polymers.

scholarly journals Electromechanical conversion efficiency for dielectric elastomer generator in different energy harvesting cycles

AIP Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 115117 ◽  
Author(s):  
Jian-Bo Cao ◽  
Shi-Ju E ◽  
Zhuang Guo ◽  
Zhao Gao ◽  
Han-Pin Luo
Keyword(s):  
Energy Harvesting ◽  
Conversion Efficiency ◽  
Dielectric Elastomer ◽  
Electromechanical Conversion

scholarly journals Methods to Improve Energy Conversion Efficiency of Dielectric Elastomer Generators

2019 ◽  
Vol 804 ◽  
pp. 63-67
Author(s):  
Heng Tong Cheng ◽  
Zhen Qiang Song ◽  
Shijie Zhu ◽  
Kazuhiro Ohyama
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Input Voltage ◽  
Energy Conversion Efficiency ◽  
Stretch Ratio ◽  
Dielectric Elastomer ◽  
Conversion Performance ◽  
Ratio Range

Dielectric elastomer generators (DEGs) are based on the electromechanical response of the dielectric elastomer film sandwiched between the compliant electrodes on each side, which are capable of converting mechanical energy from diverse sources (e.g, ocean wave) into electrical energy. In essence, DEG is a voltage up-converter using mechanical energy to increase the electrical energy of the charge on a soft capacitor. We evaluated the effect of input voltage and the pre-stretch ratios on energy conversion efficiency of DEG. With a power supply of 2.2kV and pre-stretch ratio of 2, the maximum net electrical energy density and energy conversion efficiency in a single harvesting cycle were measured to be 413 J/kg and 15.8%, respectively. The experimental results showed that, with the higher input voltage and the larger stretch ratio range, higher the energy conversion performance of DEG can be achieved.

Sign in / Sign up

Export Citation Format

Share Document