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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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Feasibility of using earth bounded ndt techniques for the space environment

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


Feasibility of using earth bounded ndt techniques for the space environment

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


Feasibility of using earth bounded ndt techniques for the space environment

MIT

Summary

  • Space Environment

  • Review of available NDT methods

  • Evaluation of NDT methods

  • Recommendations

What is this?


Feasibility of using earth bounded ndt techniques for the space environment

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?


Feasibility of using earth bounded ndt techniques for the space environment

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)


Feasibility of using earth bounded ndt techniques for the space environment

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


Feasibility of using earth bounded ndt techniques for the space environment

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)


Feasibility of using earth bounded ndt techniques for the space environment

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?


Feasibility of using earth bounded ndt techniques for the space environment

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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