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INFRARED
THERMOGRAPHYON AIRCRAFT
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Basic kit for the IRT control
Measurement chain
COMPAQ
V70
V70
(4)
(1)
(3)
(2)
Calibrationpieceheating 1- IR camera
2 – control panel of the camera
3 – Direct view on the screen
4 – Signal processing of the acquisition
INSTRUMENTATION
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Instrumentation used in IRT
Choice of the camera :
• Multiple use of the detector : IR night vision,thermal control of active sources, militaryapplication, ….
• Thermal sensitivity : (0,1 ° till 0,01 ° C)
• Acquisition frequency (25 till 300image/s)
• Line acquisition mode or Focal Plane Array (FPA)
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Instrumentation used in IRT
Heating choices :
• Different techniques : hot air blower, tubes, flashlamps, hot water, pulsed heating, laser, sun for
space shuttle, heating blanckets
• Surface heating or linear heating
• Homogeneity, reproductibility, calibration,characterization
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IRT CONTROL ON COMPOSITE
transmission technique :
14 mm
carbon
rubber
AppliedHeat
TransmittedHeat
Wi t h o u t d e f e c t With defect
T
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IRT CONTROL ON COMPOSITE
Reflexion technique :
EmittedHeat
ReflectedHeat
AbsorbedHeat
T
With defectWith out defect
14 mm
carbon
rubber
THERMOGRAM
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Temperature variation in a point
Reflexion technique :
Transmission technique :
heating
T°
time
heating
T°
time
Without defect
With defect(isolation)
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Thermographic Inspection
Advantages of the method :
• Global examination of part• Only ONE SIDE access is required for the examination• Real Time inspection• Apply for all composite structure and materials even porous
• not very sensitive to part geometry, well suited for large surfaces
Disavantages :• Sensitive to heating mode (type,duration,position)
• Response time must be studied
• Exact composition of the pieces and the thicknesses must be known
• Less definition than Ultrasonic C-Scan and Radiography
• Inhomogeneous heating on complex part
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DEFECTS ENCOUNTERED
• Lack of adhesion of cohesion, bubbles
• Delamination
• Defects on surface coatings
• Inclusions of foreign materials
• Liquid ingress
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Pulse heating method
Detection of defects inside ahoneycomb composite part
Reflexion method Heating pulse : 0.1 sec
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Pulse method – reflexion inspection on part M88
• 7 defects visible
• Contrast isdecreasing afteroptimum image
Picture of part First image Heated part at T0
Optimum image 5 Sec after10 sec after
1 2
3 4 5
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• 7 defects are detected
Transmission face 1Defects seen as dark spots
Reflexion face 1
Reflexion face 2
Transmission Vs Reflexion method
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Modulated thermography
440 mm
370 mm
carbon
14 mm
Test sample, composite bonding Carbon/Elastomer
rubber
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Phase Image Amplitude image
Method : reflexion heating, rubber sideFrequency : 0.006 HzModulation : 1000 images
Modulated thermography
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Method : transmission heating, rubber sideFrequency : 0.003 HzModulation : 1000 images
Phase imageAmplitude image
Modulated thermography
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Disbonded area
A A
Cross section AA
rubber
aluminium
kevlar
bonding
Modulated thermography
Test sample, composite bonding Metal/Elastomer/Kevlar
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Phase imageAmplitude Image
Modulated thermography
Method : transmission heating, kevlar sideFrequency : 0.006 HzModulation : 3000 images
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Conclusions
• Global method, quick, well suited for detection on composite
and complex shaped surface, and for large areas• Easy to set up on site (maintenance, expertise, productioncontrol)• Quick evolution of the technology, lower price of detectors,
new powerfull software for analysis tools will increase :• maximum inspected thickness• spatial and thermal resolution•
velocity of inspection