THERMAL'WAVE'IMAGING

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Progress in Thermosonic Crack Detection for
Nondestructive Evaluation Xiaoyan Han, L.D.
Favro, R.L. Thomas and G.M. Newaz Dept. of
Electrical and Computer Engineering, School of
Science and Institute of Manufacturing
Research Wayne State University
313-577-2970
xhan_at_ece.eng.wayne. edu robert.thomas_at_wayne.edu sk
ip_at_wayne.edu gnewaz_at_eng.wayne.edu
ACKNOWLEDGMENTS The work described in this
presentation was sponsored in part by the DOT/FAA
William J. Hughes Technical Center's
Airworthiness Assurance Center of Excellence
(AACE), under Contract Number DTFA0398D-00008,
Award Number DTFA0300PIA037, in part by the U.S.
Navy, NSWC, under P.O. Number N00167-00-M0498, by
the Office of Naval Research under Award Number
N00014-02-1-0259, in part by Universal Technology
Corporation, under Contract Number
F33615-97-D-5271, Task Order 0002-030,
Subcontract Agreement 01-S437-002-30-C1, in part
by SAIC under Subcontract Number 4400056105, and
in part by the Institute for Manufacturing
Research, Wayne State University.
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Principle of Thermosonic Imaging
Thermal Radiation Detected by IR Camera
Friction in Crack Converts Sound to Heat
Ultrasonic Power In
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Next slide contains a picture of a setup showing
an aircraft engine disk, the ultrasonic gun and
an IR camera
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Experimental Arrangement
Ultrasonic Gun
IR Camera
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In the next slide, click on the dark photo area
to observe the thermal response of a crack from
the root of the simulated anti-rotation tang that
was excited using an ultrasonic pulse of
20KHz. On other slides with dark areas, please
click to check similar thermal response due to
frictional heating of the crack surfaces.
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40kHztang3lock.avi
Thermosonic Detection of a crack in a simulated
"anti-rotation tang"
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20_21Twin.avi
Cracks in Two Adjacent Slots in a F-110 Fan Disc
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Navy_gearC1.avi
Navy_gearC2.avi
Thermosonic Detection of a subsurface crack in
a bevel gear from a helicopter William J.
Hardman (NAVAIR)
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Hand-held ultrasonic source with Tripod
design Inspecting for cracks and corrosion near
rear cargo door of B737 Testbed at AANC
Ultrasonic Source
Hand-held ultrasonic source with Tripod design
IR Camera for wide-area inspection
PORTABLE SYSTEM FOR ON-AIRCRAFT FIELD INSPECTIONS
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737carocrssion1s.avi
Corrosion Near Rear Cargo Door of B737 Testbed at
AANC
Hidden corrosion also can be detected by
thermosonics
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737BLYA_lock3.avi
TwoRevietsTwoCracks
Two Adjacent Fasteners with Cracks Caused by
Corrosion Near Rear Cargo Door of B737 at AANC
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Graphite Fiber Reinforced Composite Fatigue
Specimen with Center Hole
N4F2300_RIGHT1Rev.avi
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Boron Fiber Reinforced Composite Aircraft Repair
Patch (Simulated Disbonds)
boronpatch2.avi
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Experimental Arrangement
40kHz Ultrasonic Gun
Laser Vibrometer
IR Camera
20kHz Ultrasonic Gun
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In the next few slides, the input frequency and
its Fourier transform are shown for various
cases to assess the role of chaos on thermal
response from the cracks.
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FFT of the WaveformPure 20kHz Frequency
Waveform of the Uncoupled 20kHz Ultrasonic
Transducer
60
30
20
10
0
50
40
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FFT of the WaveformPure 40kHz Frequency
Waveform of the Uncoupled 40kHz Ultrasonic
Transducer
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Titanium Anti-rotation Tang
Velocity Waveforms
Temperature-time Curves
20KHz
(1000W)
40KHz
(800W)
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In the next few slides, one can observe the
production of higher harmonics in the material
from 20 and 40 KHz excitation in a simulated
Titanium anti-rotation tang from different
regimes of the excitation profile.
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Sevenths
5.7kHz (1/7)x(40kHz) 17.1kHz
(3/7)x(40kHz), 51.5kHz (9/7)x(40kHz), 69kHz
(12/7)x(40kHz), 109kHz (19/7)x(40kHz), ETC.
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Elevenths
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Recent Publication on New and Unusual Frequency
Behavior Acoustic Chaos
"Acoustic Chaos and Sonic Infrared Imaging",
Xiaoyan Han, Wei Li, Zhi Zeng, L.D. Favro, and
R.L. Thomas, published in Applied Physics
Letters, Vol. 81, No. 17, October 21, 2002, pp.
3188-3190.
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What is acoustic chaos?
Acoustic chaos, like mathematical chaos, is a
state of a nonlinear system in which the future
behavior of the system is so strongly dependent
on the initial conditions, that it is effectively
unpredictable. In our situation, the nonlinearity
is introduced through the coupling of the
transducer to the sample. It results in an
acoustic frequency spectrum that is one or more
sequences of rational fractions of the driving
frequency. For reasons which are not yet
understood, the chaotic behavior causes a large
increase in the IR signal from the crack.
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Summary

• Though it is a new technique, Sonic IR imaging
  (Sound in/IR out) is an excellent crack detection
  method that is sensitive, fast (lt 1 second), and
  is applicable to wide-area inspection.
• The method shows good promise for inspection of
  engine components and other structures.
• The method is applicable to a variety of
  materials, including composites.
• The discovery of acoustic chaos promises to make
  the method even more effective.