c-scan imaging for bond testing inspection
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C-Scan Imaging for Bond Testing Inspection
R. Sicard, H. Serhan
TecScan Systems Inc. www.tecscan.ca
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
Presentation Plan
• Introduction • Background on Bond Testing
• Resonance • MIA • Pitch-and-catch
• Experimental setup • Experiments:
• Sample 1: Delaminations in carbon composite plate • Sample 2: Defects in aluminum honeycomb /carbon
composite structure • Conclusion
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
•Adhesive bonded components are widely used in aerospace industry •Bond testing has typically been done with
ultrasounds • Pulse-echo UT: Echo of interface • Through-transmission: Loss of echo •Guided Waves (TT): Loss/modification of echo
Introduction
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
Specialized instruments are commercially available
Introduction
•Objective
•Combine C-Scan and Bond testing technologies
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Add intuitive image analysis offered by C-Scan • Increase data analysis possibilities • Provide better sizing capabilities
• Specialized bond testing is typically done in three modes • Resonance • MIA (Mechanical impedance analysis) • Pitch-and-catch
Background: Bond Testing
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Principle of operation • Narrowband transducer • Ultrasonically coupled to the tested part • Excitation: monochromatic wave (typically)
Bond Testing: Resonance
Ceramic
Matching layer
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Frequency is selected to optimize conditions of standing wave • Presence of disbond modify acoustic impedance and hence
resonance frequency is affected
Bond Testing: Resonance
Disbond
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
Resonance frequency is damped differently by material and is monitored as amplitude and phase changes
• Principle of operation • Dual transducer with single tip contact • Excitation: Audible waves (monochromatic) • Nulling is performed on a good bond
• Driving and receiving element are in phase
Bond Testing: MIA
Driving element
Receiving element
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
•Disbond: Change of Material Stiffness • Affects loading of the receiving element
• Receiving element no longer in phase with driving element
Bond Testing: MIA
Decrease in stiffness
Disbond
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
Difference in amplitude and phase between driving and receiving elements reveals the presence of disbonds
• Principle of operation • Separate emitter and receiver • No couplant required • Three modes of operation
• RF • Impulse (tone burst) • Frequency sweep
Bond Testing: Pitch-and-Catch
Emitter element Receiving element
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
•Waves travel from transmitter to receiver •Disbond or delamination: thin plate section
• Guided (Lamb) waves
Bond Testing: Pitch-and-Catch
Disbond
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Predominance of flexural waves A0 mode •Amplitude and phase shifts are function of
changes of thickness, i.e. presence of disbond
Bond Testing: Pitch-and-Catch
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
Experimental Setup
• BondMaster 1000e+
• 14 bit waveform digitizer
• ARMANDA: Portable XY Scanner
• TecView™ BT software
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Sample 1: Carbon/Epoxy composite with Teflon® inserts • 8 plies, 0°/90°, thickness = 1.9 mm
• Reference: 10 MHz C-Scan inspection (PE)
Depth: ~1 mm
(0.039’’)
Depth: ~1.25 mm
(0.049’’)
Experiments: Sample 1
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Resonance probe (250 kHz) • Scanning Resolution: 1 mm x 1 mm (0.025’’ x 0.025’’) • Scanning velocity: 50 mm/s (2 ’’/s)
UT (10 MHz)
BT - C-Scan of Amplitude
Experiments: Sample 1
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Phase: Variations indicate different depths • Display similar to time-of-flight or thickness C-Scan
BT - C-Scan of Phase
UT (10 MHz) - TOF
Experiments: Sample 1
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Alarms: • C-Scans based on alarm detection can provide
information about defects
BT - C-Scan of Phase
UT (10 MHz) - TOF
Experiments: Sample 1
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Sizing comparisons (-6 dB drop):
• Sizing of BT @ 250 kHz is comparable to UT @ 10 MHz
Insert 1 X
Insert 1 Y
Insert 2 X
Insert 2 Y
UT – 10 MHz 13 ± 1 mm 12 ± 1 mm 6 ± 1 mm 7 ± 1 mm
BT – 250 kHz 11 ± 1 mm 11 ± 1 mm 6 ± 1 mm 6 ± 1 mm
Insert 1
Insert 2
Experiments: Sample 1
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Sample 2: Aerospace standard for bond defects • Honeycomb cores (Aluminum)
• 0.187’’ and 0.250’’ • Composite plates (carbon/epoxy) • Typical defects
• Delaminations • Core unbonds • Excessive adhesive • Crushed cores
Experiments: Sample 2
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Resonance probe (110 kHz): • Amplitude C-Scan
Experiments: Sample 2
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Resonance probe (110 kHz) • Phase C-Scan
Experiments: Sample 2
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Null can be adjusted in post-processing • Null performed prior to inspection
Experiments: Sample 2
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Null can be adjusted in post-processing • Point Null performed in post-processing
Experiments: Sample 2
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
• Null can be adjusted in post-processing • Line Null performed in post-processing
Experiments: Sample 2
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
Conclusion
• Specialized Bond Testing benefits from C-Scan imaging • Image provides intuitive display of results • Alarm based results still apply • Sizing capabilities are improved and comparable to
conventional UT • Commercial units possess the analog outputs for
impedance-type display (Resonance & MIA) • Trigger options would be required for RF and Swept
frequency techniques (Pitch-and-Catch)
2010 ATA NDT Forum, Sheraton Uptown Hotel/Albuquerque, NM, September 20-23, 2010
TecScan Systems Inc.
75, De Mortagne Blvd., Suite 122 Boucherville (Québec)
Canada, J4B 6Y4
www.tecscan.ca
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