الفهرس 
Chapter (1): Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Friction stir welding (FSW) is a new joining process of metals in the solid-state, which means that no melting takes place during the process. This joining technique is an environmental green technology. In the aerospace field, this process can be used to make high-strength joints of aluminum, copper alloy, dissimilar materials and a variety of metallic alloys which are difficult to be welded by conventional methods. The main conception of FSW is the utilization of a rigid rotating tool with a pin, which is specially designed, and a shoulder which is inserted into abutting edges of the parts to be joined. This tool moves along the line of the joint. The tool has two main functions: (a) softening the material due to increasing the heat of the work piece, and (b) stirring the material for joint production. The friction between the tool and the workpiece is the main source of heat which is responsible for the complementation of the welding process. Plastic deformation of work piece is also another source of heat. The localized heating makes the material surrounding to the pin softer, and the combination of tool rotation and linear movement stirs the material from the front to the back of the pin. The current thesis presents numerical and experimental studies on friction stir butt-welding of Aluminum alloy (Al6061-T6). The effect of tool geometry on the developed temperature and stress distributions at welding zone has been investigated. Seven tool geometries were simulated. A coupled thermo-mechanical three-dimensional finite element models developed using Coupled Eulerian Lagrangian (CEL) approach with ABAQUS® software V.6.14. The welding process has been simulated in three steps. The first step is the plunge, then dwell step and finally welding step in which the tool was traveled with constant linear speed. The obtained result shows a significance effect of tool geometry on the distribution of temperatures and stresses developed at the welding zone. Moreover, by comparing the results of the developed models and those of the previous studies a good agreement was achieved. The experimental tests were performed to validate the numerical results such as tensile and microstructural test.