The feasibility of using earth bounded welding techniques in the space environment has been investigated. A literature survey on welding in space reveals numerous aspects about the work done in different countries. The survey indicates the need of a more detailed focus, since no welding experiments have been performed in space since July 1984 (Salyut-7). Addressing the peculiarities of different welding processes, such as environmental restrictions, helped in evaluating and analyzing the selected processes. In order to study the use of a welding process, one should also analyze the ways to test the welds produced. Consequently, non-destructive testing (NDT) techniques with potential use in the space environment were evaluated. A comparison of the various NDT techniques showed parameters, which had not been previously considered, for instance materials to be welded and type of welding processes to be used. The most probable candidates for use in the space environment were ultrasonic, radiographic and eddy current techniques. Even though mathematical modeling is not the main part of the thesis, an existing model was used in order to examine the impact of gravity on defect formation, and humping in particular, in the welding pool. Different results were generated for the Earth environment as well as the simulated space environment inside a spacecraft...
پروژه تعمیر و نگهداری قطعات جوشی در محیط فضا (Welded Repair and Maintenance in the Space Environment)، توسط آقای Vasilios Nikou از آکادمی دریایی Hellenic یونان در سال 2003 میلادی تهیه شده است. پروژه مشتمل بر 7 فصل، 114 صفحه، به زبان انگلیسی، تایپ شده، به همراه تصاویر، با فرمت pdf به ترتیب زیر گردآوری شده است:
Chapter 1: Introduction
Chapter 2: Background of Welding in Space
- Literature Survey on Welding in Space
- Considerations
- Welding Shop Location
- Automation
Chapter 3: Welding Processes for Application in Space
- Arc Welding
- (Gas Metal Arc Welding (GMAW
- Gas Tungsten Arc Welding (GTAW)
- Gas Hollow Tungsten Arc Welding (GHTAW)
- (Plasma Arc Welding (PAW
- Variable-polarity Plasma Arc Welding (PAW)
- Laser Beam Welding (LBW)
- Electron Beam Welding (EBW)
- Friction Welding Processes
- Friction Welding (FW)
- Friction Stir Welding (FSW)
- Resistance Welding (RW)
- Brazing (B)
Chapter 4: Comparative Analysis of Welding Processes
- IVA (Intravehicular Activity) Capability
- EVA (Extravehicular Activity) Capability
- Efficiency
- Versatility
- Automation
- Heat Source Density
- Radiation (x-rays, optical)
- Equipment weight
- Power Requirements
- Cost
- Advantages
- Disadvanages
- Summary
Chapter 5: Non Destructive Testing (NDT) Analysis
- Effect of the Space Environment on NDT Methods
- Zero Gravity Condition
- Space Vacuum
- Space Radiation
- Composition of the Space Environment
- NDT Method
- Visual
- Radiographic
- Ultrasonic
- Magnetic
- Penetrant
- (Electrical (Eddy current
- Acoustic Emission
- NDT Methods Evaluation
- Flaw Detection
- Materials
- Geometry of Welds
- Ease of Operation
- Safety
- Summary
Chapter 6: Generation of Defects in Micro-gravity
- Description of Possible Weld Defects
- Undercut
- Porosity
- Tunnel Porosity
- Slag inclusions
- Lack of Penetration
- Humping
- Effect of Gravity on Generation of Humping in High Current GTAW
- Geometry of the Weld Pool
- Heat Transfer
- Forces on the Transition Line
- Analysis of the Humping Mechanism Using Experimental Results
Chapter 7: Conclusions
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