feasibility of using earth-bounded ndt techniques for the space environment
DESCRIPTION
MIT. Feasibility of using Earth-Bounded NDT Techniques for the Space Environment. Explain the presentation is about NDT of welds done in space. V. Nikou, P.F. Mendez, K. Masubuchi & T.W. Eagar Massachusetts Institute of Technology, Cambridge, USA. MIT. Inspecting things in space is difficult. - PowerPoint PPT PresentationTRANSCRIPT
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Feasibility of using Earth-Bounded NDT Techniques for the Space Environment
MIT
V. Nikou, P.F. Mendez, K. Masubuchi & T.W. EagarMassachusetts Institute of Technology, Cambridge, USA
Explain the presentation is about NDT of welds done in space
![Page 2: Feasibility of using Earth-Bounded NDT Techniques for the Space Environment](https://reader035.vdocuments.mx/reader035/viewer/2022070404/56813a42550346895da2307f/html5/thumbnails/2.jpg)
MIT
February 1st, 2003
Inspecting things in space is difficult
Space Shuttle Columbia
The Need for Non Destructive Testing in Space
General NDT in space: NASA 1980?
NDT of welding in space: this work
Welding in space is at an advanced stage:Russians did it in spaceJapanese and Americans did it on planesNASA has a prototype design
Weld requirements: especially strict in spaceSpace structures: sufficient life to make economic
senseNDT in space only considered for monitoring
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Summary MIT
1) Space Environment
2) Review of available NDT methods
3) Evaluation of NDT methods
4) Recommendations
What is this?
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MIT
The Space Environment
1. Zero Gravity:• Low Gravity condition (g/g0=10-5 to 10-7)• Physics change (density, convection, surface tension)
2. Space Vacuum:• Mean pressure @ 250-500Km in the order of 10-9 Atm• Thickness of residual atmosphere is very small• Local pressure gradients instantaneously equalized
3. Space Radiation:• Vacuum Ultraviolet radiation (VUV)• Wide temperature variations on structures (–1100C to 1500C)
4. Composition of space environment:• Atomic Oxygen (very corrosive)• Atomic Hydrogen• Space Debris• Meteoroids
What is this?
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NDT Methods ReviewedMIT
1. Visual (easy, less accurate)
2. Radiographic (very sensitive, portable, radiation hazard)
3. Ultrasonic (space-graded compounds needed as couplants)
4. Magnetic (surface defects, dry method OK)
5. Penetrant (can operate only up to 10-5 Atm)
6. Electrical-Eddy Current (surface and shallow crack detection)
7. Acoustic Emission (has to be detected in real time, better for
monitoring)
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NDT Methods ReviewedMIT
1. Visual
2. Radiographic
3. Ultrasonic
4. Magnetic
5. Penetrant
6. Electrical (Eddy Current)
7. Acoustic Emission
1. Radiographic
2. Magnetic
3. Ultrasonic
4. Eddy Current
Use a consistent order for sorting them.
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MIT
NDT (Welding - Monitoring)
Flaw detection
WeldgeometryMaterials
Safety Versatility
NDT Techniques Performance Factors
Flaw Detection: Minimum detectable flaw size Maximum detectable flaw depth
Materials: Al Ti Metal Matrix Composites (MMC) Austenitic Stainless Steel Martensitic Stainless Steel
Geometry of welds:
Brazing (B) Electron Beam Welding (EBW) Laser Beam Welding (LBW) Arc Welding (AW) Resistance Welding (RW)
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Methods Radiographic Ultrasonic Magnetic Eddy current
Size 2% of thickness > 1-5 mm depending on
frequency
> 0.5 mm > 0.1 mm
Fla
w
Det
ecti
on
Depth 25mm SS
80mm Al
<500 mm Surface or near surface cracks
<13 mm SS
<3.5 mm Al
Al Y Y N Y
Ti Y Y N Y
MMC Y Y N N
SS1 Y N N Y M
ater
ials
SS2 Y Y Y Y
B Y N N N
EBW Y Y N Y
LW Y Y N Y
AW Y Y N Y
Geo
met
ry o
f w
eld
s
RW N N N Y
Ease of operation
Good Good Good Good
User’s Safety Radiation None None None
NDT Methods Evaluation
• Eddy Current: most suitable
•Why?
• Ultrasonic: maybe for MMC
•Why?
• Radiographic:
•heavy
• Magnetic: less suitable
•Why?
MIT
Explain why in little bullets
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Conclusions
No welding in space without NDT of welds
Review of NDT methods for welds made in space
Earth-bounded NDT processes could be used in space
Eddy-Current most all-around suitable technique
Ultrasonic suitable for MMC
Future work involves examining the defect generation of specific
welding methods