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filercaliforniaMechanics

Nov 14, 2013 (3 years and 11 months ago)

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Project 11566:

ITT Magnetic Damper

Tom
Sciotto

(IE), Project Leader

Jacob Norris (ME)

Tiffany
Heyd

(ME)

Ben
Hensel

(ME)

Dampening satellite vibrations


Imagine a satellite in orbit


Rapid, jerky, but small motions (moving
camera parts) on satellite induce vibrations


But satellite is physically isolated; vibrations
can’t dissipate


So: need a dampener!

Satellite Design

Space Environment


Wide temperature range


-
40
°
C to 80
°
C


Too wide for hydraulic dampener


Vacuum and radiation


Rubber or solid
-
state dampener would harden


ITT decided: Electromagnetic dampening

Eddy Current Dampening


Used an induced
emf

to resist a magnet


Train brakes:


Lenz’s Law


“An induced current is always in such a
direction as to oppose the motion or change
causing it



Electromagnetic interpretation or result of
Newton’s Third Law

How Eddy Currents Work


Conductor
-
Magnet relative motion induces
current in conductor


Current creates magnetic field


Induced magnetic field opposes magnet;
strength proportional to flux, or relative speed


Dampening constant, c!

Eddy Currents in Action

Wheel (rotates)

Conductive Plate

Magnet

(but our application
is linear not angular)

Mathematical Model


Damped mass
-
spring system






Equation of Motion

𝑚
𝑥

+
𝑐
𝑥

+
𝑘𝑥
=
0

Mathematical Model

𝑚
𝑥

+
𝑐
𝑥

+
𝑘𝑥
=
0


𝑥

+
2𝜁
𝜔
0
𝑥

+
𝜔
0
2
𝑥
=
0

Where


𝜔
0
=
𝑘
𝑚
,
𝜁
=
𝑐
2𝑚
𝜔
0
=
𝑐
2
𝑚𝑘