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
