Asegun Henry, Makola Abdullah Ph'D'

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Structural Magnetic Induction Damper

• Asegun Henry, Makola Abdullah Ph.D.
• FAMU-FSU College of Engineering
• Tallahassee Florida

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Outline

• Problem - Proposed Mitigation
• Analysis
• Equation of Motion
• Magnetic Induction
• Device Setup
• Simulation Equations
• Results
• Conclusion
• Future Work

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Problem - Solution

• Earthquakes cause structural damage
• Control system to reduce vibration
• Structural magnetic induction damper (SMID)
• Passive device
• Tuned to resonant frequency of structure
• Harnesses energy

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Simulation Scheme

• Two-dimensional analysis
• Device attached to
• top floor with spring
• Damping via interaction
• of magnetic field and coil

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Equation of Motion
Displacement
M Mass K Stiffness C
Damping
Ground Acceleration
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Magnetic Induction

• Charged particles have electric fields
• Interaction of electric fields creates forces
• Charged particles experience forces parallel to
  the E-field lines

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Magnetic Induction

• Changing magnetic fields induce electric fields
• Force exerted on the charged particles
• due to electric field
• Emf is th sum of the electric
  field around the loop

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Magnetic Induction

• Emf is synonomous to Voltage
• Moving particles are current
• Magnetic flux is magnetic field perpendicular to
  area
• Voltage is change in flux (Faradays Law)

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Device Setup

• Magnetic field generated by two flat permanent
  magnets
• Magnetic poles are oriented to create field
  between
• Flat magnets are mounted to large mass

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Device Setup

• Coil fixed to top floor
• Large mass with magnet connected via spring
• Magnetic field perpendicular to coil loop
• Relative velocity of floor and magnet induces
  voltage
• Coil connected to load

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Simulation Equations

• N Number of coil turns
• Bn Magnetic field strength
• A Flux area in coil loops
• w Width of coil loops

x Length of section exposed V Voltage I
Current R Resistance F Force
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Magnetic Damping

• F Force
• C Damping constant
• v Velocity
• R Resistance

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Simulation Parameters

• One Story Building
• Floor mass 100,000 kg
• Column stiffness constant 100,000 kg/s2
• Column damping ratio 1
• Column Damping constant 2000 kg/s
• El Centro Earthquake (Mag. 7.1)

• Device attached to top floor
• Mass of Magnet 15,000 kg
• Number of coil turns 125
• Width of loops 4 m
• Magnetic field strength 2000 Gauss
• Load Resistance 1 Ohm

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Results
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Results
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Results
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Results
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Conclusion

• SMID can be modeled and function mechanically as
  a TMD
• SMID can reduce structural vibration
• Can harness energy transmitted to structure

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Future Work

• Detailed analysis and modeling of electrical
  output
• Consider modeling and design issues
• Distance between magnets
• Limit to number of coil turns
• Boundary design at peak excitation

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Acknowledgements

• NSF
• Florida A M University
• FAMU-UP UROP
• Dr. Abdullah