x-ray backscatter imaging for aerospace applications - nasa
TRANSCRIPT
Nucsafe and Scatter X-ray Imaging are a trademarks of Nucsafe, Inc. Copyright © 2010 Nucsafe, Inc. All rights reserved. 07/22/2010 | 1
BOEING is a trademark of Boeing Management Company. Copyright © 2010 Boeing. All rights reserved.
X-ray Backscatter Imaging for Aerospace Applications
Gary Georgeson, Talion Edwards, Jim Engel – Boeing Research & Technology Dan Shedlock – Nucsafe Inc.
07/22/2010 | 2 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
X-ray Backscatter vs. Traditional X-ray
Transmission X-ray
Pros • Simple Equipment • High resolution in favorable conditions • Access to small areas
Cons • High radiation field • Requires access to both sides • Large area coverage takes many shots • Images require post processing for most
Backscatter X-ray
Pros • Automated Collection • Fast Data Collection / Real-time imaging • Low radiation field • Single sided process • Large area images
Cons • System cost • Physical size/complexity of system • Resolution dependant on standoff
X-ray Image
Transmission X-ray Detector
Backscatter X-ray Detector
X-ray Tube X-ray Tube
Rotating Collimator
07/22/2010 | 4 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
System Description
• Scanning head consist of • x-ray tube • Illumination beam collimator • Detectors to measure the backscatter signal
• Can be adapted to use any X-ray energy
• Energy required dependant on application • Uses COTS X-ray tubes • Currently systems available from 160-225 kV
• Design of collimator and aperture
• Can be pointed in different directions • Tailoring of aperture size for different applications
• Configurable Detector Arrays
• Different size detectors and detector combination allow for easy customizations to applications
• May use Radiography by Selective Detection (RSD) to enhance image contrast and subsurface resolution
X-ray Backscatter Scanning Head
07/22/2010 | 5 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
System Description (cont)
Mobile System
• The linear rail system is mobile and can be expanded to image different lengths
• Designed to work in different orientations (straight-up,
up-side-down) • Modular to setup and move with 2 people
Robotic System
• X-ray backscatter imaging for any complex motion profile • Allows end user customized motion • Combines state-of-art off the shelf motion with x-ray
backscatter imaging
• Robotic System offers customized motion for each application
07/22/2010 | 6 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Aerospace Operational Considerations - Portability
• Packaging design for use in and around aircraft
Compatibility with Ground Support Equipment Sized for ingress and egress
• Minimize Potential for FOD
• Portability and Setup • Shipping size and Transportability • High Voltage Connections
• Power Service Requirements
07/22/2010 | 7 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Aerospace Operational Considerations - Automation
• Integration into manufacturing area
Availability of Shop Floor Space Compatibility with Ground Support Equipment
• Motion programming
• Multiple DOF require additional safety planning
• Mounting provisions and power service
07/22/2010 | 8 Copyright © 2010 Boeing and Nucsafe. All rights reserved. Copyright © 2010 Boeing and Nucsafe. All rights resrved.
Aerospace Operational Considerations (cont.)
• Safety to aircraft electronics • FCC testing for EMI/EMR shielding • Affect of ionizing radiation on sensitive solid state electronics
• Radiation safety
• Long exposure times required create the need to implement multiple layers of safety into deployable system
• Occupational & nonoccupational exclusion zones • Defeating perception of danger based on experience with
traditional transmission X-ray • Challenge in measuring field strength of highly collimated
moving source with traditional field survey meters
• Other safety considerations • Robotic motion hazards • Ergonomics of handling, assembling and disassembling in
confined areas
07/22/2010 | 9 Copyright © 2010 Boeing and Nucsafe. All rights reserved. 05/5/2010 | 9 Copyright © 2010 Boeing and Nucsafe. All rights resrved.
Application of X-ray Backscatter for Aircraft NDE
• Low z materials typical to aircraft suited to backscatter • Many NDE inspections at known locations and depths • Ability to image through multiple layers • Continuous contact with nested layers not required as
with other NDE techniques
07/22/2010 | 10 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Contributors to Image Quality
• Speed – directly related to image quality by counting statistics (inherence noise in the image)
• Standoff
• Illumination pencil beam diverges from the x-ray source • Backscatter signal decreases with a 1/R2
• Size and Weight – related to image quality at given speeds
• More intense x-ray sources (higher mA) require larger tubes, generators and cooling capacity
• Larger area detectors can increase capture of scatter • Type of detector material
07/22/2010 | 11 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Affects of Standoff on Image Resolution
• Standoff is driver in spatial resolution of images • At reduced standoff, edge definition is significantly improved, contrast has
increased, and much smaller features can be resolved 150 mm Standoff 450 mm Standoff
5 mm/s 5 mm/s
100 mm/s 100 mm/s
07/22/2010 | 12 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Affects of Standoff on Image Resolution (cont.)
SXI image at 150 mm standoff
SXI image at 450 mm standoff
• At 3x the standoff, contrast decrease by about 9% • Resolution falls off with contrast as the standoff is increased. • Statistical noise increased from 1.26% to 1.54% or increased by 20%. • Statistical noise increases with standoff follows Poisson counting statistics
varying with the square root of the contrast intensity value. • Resolution lost by standoff partially recoverable using smaller apertures
• Scan speed must be reduced by a factor proportional to the reduction of the open area of aperture.
• Standoff is critical to application development
40
60
80
100
120
140
160
0 10 20 30 40 50 60 70 80
150 mm, 5 mms450 mm, 5 mm/s150 mm, 20 mm/s
07/22/2010 | 13 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
X-Ray Backscatter NDE Applications
• Corrosion Detection • FOD Detection • Fluid Intrusion • Cracks and Defects
07/22/2010 | 14 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
• Advantages of X-ray Backscatter Imaging • Ability to image large area from with single sided access • Real time imaging allows recursive scanning • Low radiation field allows smaller exclusion zones • No continuous media required for second layer inspection • Image based technique allows for easy interpretation
• Challenges to adoption of technique
• Development of new standards/procedures • High scan speeds require large equipment • Limited available of tailored x-ray sources • Detailed depth information requires longer scans • Site specific radiography requirements
Conclusions
07/22/2010 | 15 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Snakes on a Plane
Gary Georgeson, Joe Hafenrichter, Bill Motzer Boeing Research & Technology
Seattle, WA
NASA In-Space NDI Workshop
February 29- March 1 Houston, TX
07/22/2010 | 16 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
A
A B
B
C
C
Planes have many difficult to access areas.
07/22/2010 | 17 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
B” – B”
Snakes Can Move through Access Holes
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Potential Fuselage Applications
A - A Depaint
Lap Joint & Scribeline Inspection
Inspection for Corrosion
under Galleys and
Lavs
Inspection for Wire
Fault
Inspection of Control
Cables
Inspection of Fasteners for
Lightning Strike Damage
Inspection of Floor Beams
Inspection for Keel
Corrosion
Inspection of
Frame Crack
Inspection Behind
Insulation
Inspection Behind
Lavs and Galleys
Inspection Behind
Equipment
Inspection of Closed Section
Stringers
07/22/2010 | 19 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
B”’ – B”’
Inspection of Bonded
or Co-Cured Joints
Inspection of Bonded Joints
B”’ – B”’
Paired Through
Transmission Inspection of Bonded
Joints
Paired Through
Transmission Inspection of Bonded
Joints
07/22/2010 | 20 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
B - B
Inspection of IML
Sandwich Structure
Inspection of Sandwich Panels
B - B
Paired Through Transmission Inspection of
Sandwich Structure
07/22/2010 | 21 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Potential Wing and Fuel Tank Applications
Corrosion Inhibitor
Application
Landing Gear Bay Corrosion Inspection
Inspection of Side of Body
Joint
Exterior Wash
Inspection under Fuel
Bladder
Limited Access Scarfing
LSP Grid Inspection
Stringer Inspection
Paired Through
Transmission Inspection
(TTU, X-Ray, Other)
C - C
Swimming Snake In-
Tank Inspection
Swimming Snake
inspecting Pipes and Tubes
07/22/2010 | 22 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Inspection of
Landing Gear Bay Cracks
and Corrosion
Inspection of
Landing Gear
Cracks
Inspection of Landing Gear
Doors
Landing Gear and Wheel Wells
07/22/2010 | 23 Copyright © 2010 Boeing and Nucsafe. All rights reserved.
Robotic Snakes are of interest to Boeing