DESIGN AND CONTROL OF A TUNABLE VIBRATION NEUTRALISER Mike Brennan Institute of Sound and Vibration

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DESIGN AND CONTROL OF A TUNABLE VIBRATION
NEUTRALISERMike Brennan Institute of Sound
and Vibration ResearchUniversity of Southampton,
UK
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Tunable Vibration Absorbers
The Vibration Absorber What does it do?
frequency
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Tunable Vibration Absorbers
what are they used for?

• Absorber Tuned to suppress the
• response at a
• troublesome resonance
• frequency

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Tunable Vibration Neutralisers
Change damping
frequency
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Research Objective

• How to change stiffness in real-time?

• Review

• Description of two mechanisms
• Shape memory alloy
• Shape change

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Tunable Devices (vary stiffness)
M.A. Franchek, M.W. Ryan and R.J. Bernhard 1995.
Journal of Sound and Vibration, 189(5), 565-585.
Adaptive Passive Vibration Control
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Tunable Devices (vary mass)
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Tunable Devices (vary stiffness)
D.P. Hong and Y.S. Ryu 1985. US Patent No.
4935651. Automatically Controlled Vibration
Absorber
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Tunable Devices (vary stiffness)
A.K. Abu-Akeel 1967, Journal of Engineering for
Industry, 741-748. The Electrodynamic Vibration
Absorber
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Pneumatically Controlled Vibration Neutraliser
(50-100Hz)
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Beam-Type Neutraliser
m
k
excitation
L
effective mass of the beam
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Beam-Type Neutraliser
hdistance between beams dthickness of one beam
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Beam-Type Neutraliser
Servo motor
35 change in natural frequency
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Shape Memory Alloy Beam-Like Neutraliser
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Change in Stiffness shape memory alloys

• Elastic modulus changes from 40 to 59 MPa
• Hysteresis of about 10C

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Shape Memory Alloy Beam-Like Neutraliser

63.9 Hz
77.6 Hz
17.5
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Shape Memory Alloy Beam-Like Neutraliser
temperature (ºC)
increasing temperature
natural frequency
frequency (Hz)
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Shape Memory Alloy Beam-Like Neutraliser
temperature (ºC)
decreasing temperature
natural frequency
frequency (Hz)
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Control
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Control
Measure phase angle ? and set
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Control Algorithm

• The controller updates the output current every
  Tn seconds
• en is the evaluation of cosF at the nth time step
• The current at the (n1)th time step
• P Constant of the non-linear proportional part
• D Constant of the derivative part

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Performance

• Good performance also with the real ATVN
• No oscillation around the equilibrium point
• Constant excitation frequency 59Hz from qamb

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Adaptive Neutraliser using Shape Change

• Two designs

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Variable stiffness using shape control- varying
geometry of a hinged arch
F
B
L
L
y0
y
C
A
rigid links
cantilevers stiffness k
2b
(b) deformed
(a) undeformed
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Hinged Arch ATVN
adjustable distance 2b
absorber mass
4 cm
L
L
rigid links
cantilevers
mechanism
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Tuning characteristic
40
predicted
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measurment
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10
0
increase in tuned frequency
-10
-20
-30
-40
-50
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
increase in b / L
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Variable stiffness using shape control - change
in curvature
mass
Curved beams
Host structure
Low natural frequency
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Variable stiffness using shape control - change
in curvature
u
s
p
h
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Adaptive Neutraliser using shape change
natural frequency 38 Hz - 46 Hz
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Adaptive Neutraliser using shape control
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Frequency sweep test NO CONTROL vs P-D CONTROL
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Summary

• Variable stiffness devices reviewed
• Shape memory alloy vibration neutraliser
  described
• Adaptive vibration neutralisers using shape
  change described