friction stir welding simulation in ansys tutorial pdf
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Agitating friction welding (FSW) is a solid state welding technique involving the attachment of metals without fillers. A cylindrical rotary tool is immersed in a rigidly fixed workpiece and moves along the joint to be welded. As the tool moves along the joint, heat is generated by friction between the tool shoulder and the workpiece. The additional heat is generated by plastic deformation of the workpiece material. The heat generated produces a thermal softening of the material of the workpiece. The translation of the tool causes the material of the softened part to flow from the front to the back of the tool where it is consolidated. As cooling occurs, a solid solid joint is formed between the two plates. No melting occurs during the process, and the resulting temperature remains below the solidus temperature of the metals that are bound. FSW offers many advantages over conventional welding techniques and has been successfully applied in the aerospace, automotive and shipbuilding industries.
Thermal and mechanical behavior are mutually dependent during the FSW process. Because the temperature field affects the voltage distribution, this example uses a fully thermally-coupled model. The model consists of a solid field element coupled with structural and thermal degrees of freedom. The model has two rectangular steel plates and a cylindrical tool. In the model all the necessary mechanical and thermal limit conditions apply. The simulation takes place during three stages of loading, representing the phases of immersion, permanence and process travel.
The temperature increases at the contact interface due to the frictional contact between the tool and the workpiece. FSW generally occurs when the temperature in the region of the weld line reaches 70 to 90 percent of the melting temperature of the workpiece material. The temperature obtained around the region of the weld line in this example is within the range indicated by Zhu and Chao and Prasanna and Rao, while the resulting maximum temperature is well below the melting temperature of the workpiece. Calculated friction heat generation and plastic heat generation show that friction between the tool flange and the workpiece is responsible for generating most of the heat. A bonding temperature is specified at the contact interface of the plates for modeling the weld behind the tool. When the temperature at the contact surface exceeds this bonding temperature, the contact changes to bonded.
It can be understood in the following video: