| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 101 === The present study was to investigate the friction stir spot welding (FSSW) process, material flow and temperature behavior without probe,using Finite Difference Method to simulate and analyze the material flow and temperature changes and compare with experiment in the welding process. Use cylindrical coordinates to create a three-dimensional steady-state friction stir welding process model. The theoretical simulation of fluid dynamics based model, while solving the continuity equation, momentum conservation, and energy balance equations.
The speed of surface close to the workpiece are assumed to be known in past studies. This study is divided into two parts, Where in pure sliding portion, assuming that the surface speed of the material is zero, partial sticking is assumed that the surface speed is unknown,
The calculation of surface speed on workpiece let the shear stress of the tool equal to viscous shear stress of material. Finally, we discuss the temperature rise and the effect of sticking ratio by pressure or plunge force on the workpiece.
The study found that start generating the material flow of the workpiece is not always occur by high temperature point, but with the friction coefficient and pressure. The study also found that the sticking occurs in the direction from the center of the workpiece to the shoulder edge. In the experiment ,the state to achieve full sticking in the shoulder edge, is almost impossible happen.
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