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Feasibility of using Earth-Bounded NDT Techniques for the Space Environment PowerPoint PPT Presentation


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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.

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Feasibility of using Earth-Bounded NDT Techniques for the Space Environment

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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

February 1st, 2003

Space Shuttle Columbia

General NDT in space: NASA 1980?

NDT of welding in space: this work

The Need for Non Destructive Testing in Space

  • Welding in space is at an advanced stage:

    • Russians did it in space

    • Japanese and Americans did it on planes

    • NASA has a prototype design

  • Weld requirements: especially strict in space

  • Space structures: sufficient life to make economic sense

  • NDT in space only considered for monitoring


MIT

Summary

  • Space Environment

  • Review of available NDT methods

  • Evaluation of NDT methods

  • Recommendations

What is this?


MIT

The Space Environment

  • Zero Gravity:

    • Low Gravity condition (g/g0=10-5 to 10-7)

    • Physics change (density, convection, surface tension)

  • 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

  • Space Radiation:

    • Vacuum Ultraviolet radiation (VUV)

    • Wide temperature variations on structures (–1100C to 1500C)

  • Composition of space environment:

    • Atomic Oxygen (very corrosive)

    • Atomic Hydrogen

    • Space Debris

    • Meteoroids

What is this?


MIT

NDT Methods Reviewed

  • Visual (easy, less accurate)

  • Radiographic (very sensitive, portable, radiation hazard)

  • Ultrasonic (space-graded compounds needed as couplants)

  • Magnetic (surface defects, dry method OK)

  • Penetrant (can operate only up to 10-5 Atm)

  • Electrical-Eddy Current (surface and shallow crack detection)

  • Acoustic Emission (has to be detected in real time, better for monitoring)


MIT

NDT Methods Reviewed

Use a consistent order for sorting them.

  • Visual

  • Radiographic

  • Ultrasonic

  • Magnetic

  • Penetrant

  • Electrical (Eddy Current)

  • Acoustic Emission

  • Radiographic

  • Magnetic

  • Ultrasonic

  • Eddy Current


MIT

Flaw

detection

Weld

geometry

Materials

NDT

(Welding - Monitoring)

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)


MIT

NDT Methods Evaluation

Explain why in little bullets

  • Eddy Current: most suitable

    • Why?

  • Ultrasonic: maybe for MMC

    • Why?

  • Radiographic:

    • heavy

  • Magnetic: less suitable

    • Why?


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


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