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PowerPoint Presentation
A Displacement Dependent Damper for a Vibration Based Energy HarvesterAsil A. AksekiliYeditepe University
19 December 2012, Atasehir- Istanbul Hello everyone.Welcome to my presentation.I am Asil Aksekili form Yeditepe University ,Mechanical Engineering Department.Now, I am going to present you one of our current study,which is named as A Displacement Dependent Damper for a Vib. Based Energy Harvester
1OutlineWhat is energy harvesting?
Conventional energy harvesters and problem definition
Proposed system: Nonlinear damping
Simulations
Results and discussion
Experimental Study
Conclusions2Here is the outline of my speech.Before getting into the more detailed stuff, I will make a breef introduction to energy harvesteringAnd than, I will talk about conventional, vibration based, energy harvesters and the design problems associated to them.The most common solutions deals with these problems are also going to be mentioned at that part.Following that, our proposition of using nonlinear damping in these systems will be introduced.The simulations and the results of the system wil be covered.And at the end i will make a conclusion and talk about future works.2Energy Harvesting
Definition: Energy harvesting is the process to convert ambient energy source into electrical energy
Ambient Energy SourcesSolarWindThermalVibrationalEtc..Usage AreasWireless sensorsStructural health monitoring Biomechanic applicationsEtc..
33Vibration Energy HarvestingUses vibration as ambient energy sourcePractically advantageous when solar energy is not available 4
4Challenges in design stageVariable frequency and amplitude characteristics of the ambient source Small dimensions restricts the movement of the proof massVibration Energy HarvestingLinear Model5
5Hardening mechanism
Bistable mechanism
6
[1] M. Ferrari, Improved energy harvesting from wideband vibrations by nonlinear piezoelectric converters, Sensors and Actuators A 162: 425-431 (2010)
Nonlinear Springs
[1]
6Nonlinear SpringsHardening mechanism [2]Works with relatively slow frequenciesRequires proper frequency range
Bistable mechanism [2]The level of vibration should be above the threshold value of the designed mechanism
7[1] M. Ferrari, Improved energy harvesting from wideband vibrations by nonlinear piezoelectric converters, Sensors and Actuators A 162: 425-431 (2010)[2] L. Tang, Y. Yang and C. K. Soh, Toward Broadband Vibration-based Energy Harvesting, Journal of Intelligent Material Systems and Structures 21: pp. 1867 (2010)
[1]
7Nonlinear Damping
BoundaryBoundaryProposed SystemIncrease damping of the system as the proof mass approaches to the boundaries and keep it minimum while the proof mass passes through the mid point of its travel spanGoalsIncrease average velocity of the proof massPrevent collision with boundariesIncrease the optimum working frequency and amplitude region of the device
Increase Efficiency
88Nonlinear DampingLinear ModelNonlinear Model
9n: nonlinearity termLinear dampingNon-linear dampingNon-linear damping
9SimulationsParameterValuem [kg]0.02 [rad/s]7.75 - 155k [N/m]120Zl [m]0.01Y0 [m]0.01 0.1Dn?How to determine DnDn is optimized for each data point (i.e. / n and Zl / Y0 value) based on the following algorithm.Simulations are made for n=0 linear damping case and n=1,n=2 nonlinear damping cases1010SimulationsFor each data pointDn is optimized for maximizing the harvested power.It is checked whether the proof mass collides with the boundaries or not.If there is collision, Dn is increased (reoptimized) until the collision is prevented
11SimulationsSolve differential equation numerically by using MATLAB ODE45Find equivalent powerFind normalized power12
Optimize Dn Calculation flow
12Results and Discussion
= 50 rad/s
13z(t) (mm)Time (s)13Results and discussionNormalized power for n = 0
14Results and discussionNormalized power for n = 1
15Results and discussionNormalized power for n = 2
16Results and Discussion
17Percentage Differences in Normalized Power
N. Topaloglu, A. A. Aksekili and B. Yegin, 2011, A Displacement Dependent Damper For A Vibration Based Energy Harvester,SET 11,10th International Conference on Sustainable Energy Technologies, Sep. 4-7, 2011, Istanbul, Turkey.
N. Topaloglu, A. A. Aksekili and B. Yegin, 2011, An Optimized Damping Model for Vibration Based Energy Harvesters with Constrained Proof Mass Motion, IWPMA 2011 and the6thAnnual Energy Harvesting Workshop, Aug. 7-11, 2011, Roanoke, VA, USA.
N. Topaloglu, A. A. Aksekili, An Optimized Damping Model for Vibration Based Energy Harvesters with Constrained Proof Mass Motion",Journal of Intellegent Material Systems and Structures(Submited).
17Results and Discussion
18Percentage Differences in Normalized Power
N. Topaloglu, A. A. Aksekili and B. Yegin, 2011, A Displacement Dependent Damper For A Vibration Based Energy Harvester,SET 11,10th International Conference on Sustainable Energy Technologies, Sep. 4-7, 2011, Istanbul, Turkey.
N. Topaloglu, A. A. Aksekili and B. Yegin, 2011, An Optimized Damping Model for Vibration Based Energy Harvesters with Constrained Proof Mass Motion, IWPMA 2011 and the6thAnnual Energy Harvesting Workshop, Aug. 7-11, 2011, Roanoke, VA, USA.
N. Topaloglu, A. A. Aksekili, An Optimized Damping Model for Vibration Based Energy Harvesters with Constrained Proof Mass Motion",Journal of Intellegent Material Systems and Structures(Submited).
18Results and Discussion
1919Results and Discussion20Comparison of numeric results with analytical model (Harmonic Balance Method)
Nonlinear Equation:Assumptions:Harmonic motion2-term analytical solution4-term analytical solutionResults
for n=2Max Difference (%)Average Difference (%)2-term Assumption9.824.114-term Assumption4.991.6520Experimental Study
CoilsSymmetry AxisMagnets
Harvester design
21Experimental Study
CoilsSymmetry AxisMagnetsSpring HoldersCross section of the harvester
22Experimental Study
ComputerControllerShakerOscilloscopeHARVESTER23Experimental Study
MagnetsCoilsServoPulley24AIM: Determinig damping on the proof mass (magnet) as a function of coil turn numbers.
ConclusionNonlinear damping system is proposed as an alternative to the current solutions for vibration based energy harvesters.
The linear and nonlinear systems are simulated and results are compared for a given dataset values.
It is found that the efficiency of the system can be improved by adopting nonlinear damping however, the performance increase depends on the design parameters.
Nonlinear dampers can be a potential for energy harvesters.
Finishing up the experimental validation of the theory. (ongoing)
2525Thank you for listening
Asil A. Aksekili
[email protected] University, Department of Mechanical Engineering
Istanbul, Dec. 20122626