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

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

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  1. 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

  2. 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

  3. MIT Summary • Space Environment • Review of available NDT methods • Evaluation of NDT methods • Recommendations What is this?

  4. 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?

  5. 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)

  6. 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

  7. 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)

  8. 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?

  9. 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