Detecting Cracks under Bushings Detecting Cracks under Bushings in - - PowerPoint PPT Presentation

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Detecting Cracks under Bushings Detecting Cracks under Bushings in Aircraft Structures in Aircraft Structures Using FG RFEC & SSEC Technique Using FG RFEC & SSEC Technique

Yushi Sun, Harry Zh Yushi Sun, Harry Zhu Innovative Materials Testing Technologies, Inc. Tom Mora Tom Moran, John C. Brau n, John C. Brausch, Ke sch, Kenne nneth J. LaC th J. LaCivita vita AFRL/ML Anderson Danny, Th Anderson Danny, Thomsen Mark

• msen Mark

HILL AFB Lisa Brasche Lisa Brasche CNDE, ISU Michael Harper Michael Harper Ames Lab, DoE

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

• 1. A challenge to detect cracks in cross-

bolt holes when the cracks are located beneath repair bushings. 2.Removal of a bushing is costly and may bring new damage to the holes. 3.There has been a demand for techniques that is capable of detecting cracks in cross-bolt holes through a bushing.

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

FWD AFT

Holes 3, 4 Holes 1, 2 Holes 3, 4 Holes 1, 2 Holes 1 & 2: 7 Layers Holes 3 & 4: 5 Layers

Target Aircraft Component: Wing Attach Fitting Inspection through bushing.

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

0.300” 2024-T3511 0.094” SHIM 0.344” 2024-T3511 0.320” 4340 C(A) d E F(H)

Φ 0.50” Fastener Holes

INCONEL 718 Bushings

50”×50” EDM #1 100”×100” EDM #2

Test Standard

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Probe Developed: RF BSH0.5 Test Frequency: 10 kHz - 80 kHz

180 360 90 270 Unwrapped surface of probe head [ º] Drive Coil Pickup Coil Z

Rotation Guide with ball-bearing Part for Z-Position Slip Ring Connectors Rotation Handle Permanent Magnet Probe Holder Probe head

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Simulated Reflection Differential Mode with step = 5 points Digital LPF, cutoff frequency = 1.0 Hz

SSEC Settings – A Screen Copy

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Probe Position 1 Z = 0.885”

Real, X [25 mv per grid] Real, X Imaginary, Y [25 mv per grid] Imaginary, Y Sample Points Data Buffer Steel Z Coil EDM #1 EDM #2 EDM #1: 50”×50” EDM #2: 100”×100”

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Position 2 Z = 0.715” EDM #2 can be detected from Z=0.685” to Z=0.760”

Real, X [25 mv per grid] Real, X Imaginary, Y [25 mv per grid] Imaginary, Y Sample Points Data Buffer Steel Z Coil EDM #1 EDM #2 EDM #1: 50”×50” EDM #2: 100”×100”

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Probe Position 1 Z = 0.565”

Real, X [25 mv per grid] Real, X Imaginary, Y [25 mv per grid] Imaginary, Y Sample Points Data Buffer Steel Z Coil EDM #1 EDM #2 EDM #1: 50”×50” EDM #2: 100”×100”

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Position 2 Z = 0.395” EDM #1 can be detected from Z=0.395” to Z=0.415”

Real, X [25 mv per grid] Real, X Imaginary, Y [25 mv per grid] Imaginary, Y Sample Points Data Buffer Steel Z Coil EDM #1 EDM #2 EDM #1: 50”×50” EDM #2: 100”×100”

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Conclusions

• 1. The two EDM Notches made on layer E are detected with

high S/N ratios.

• 2. The permanent magnet probe holder and the ball-bearing

rotation guide help with noise reduction and ease of

• peration.
• 3. Comparing the signal responses of the two notches the

0.100”×0.100” EDM Notch, Notch #2, can be detected in a large range of probe position Z, see Page 8.

• 4. The 4340 steel layer enhances the signal response from

the 0.050 ”×0.050” EDM notch, Notch #1. However, it moves the location for optimal detection towards steel side, see Page 10.

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Inno Innovative Materials tive Materials Testin Testing T Tech chnologies, es, I Inc. c.

Air Force Research Laboratory Center for Nondestructive Evaluation

Future Work

• 1. Motorize probe rotation
• 2. Automatic C-Scan and Real-Time Imaging
• 3. Consider thickness variation of bushing
• 4. Try detection of bore-hole crack with and

without an installed bushing.

• 5. Commercialization
• 6. Field testing and POD study