Solid Mechanics Based Finite Element Simulation of FSW Process

Friction stir welding (FSW) is a fairly new solid-state joining process with many advantages over traditional fusion welding. In FSW, as shown in Fig.1 for a butt weld, the pin of a rotating tool is plunged into the seam between two plates and is made to move along the seam while it is rotating, forcing the workpiece material to flow around the pin. Together with the tool shoulder, the pin creates a hydrostatic pressure in the workpiece material, which, when coupled with heating generated by friction between the workpiece and the pin and shoulder and by plastic deformation in the workpiece, consolidates the workpiece material from the two plates and joins the plates together.

The objective of this research is to understand and characterize the Friction Stir Welding process though solid mechanics based finite element simulations. These simulations take the following points of consideration:
Given here is a brief summary of our current effort at modeling and simulating the material flow pattern in FSW process using solid mechanics based finite element tools. Several modeling approaches are being developed for characterizing material flow around the rotating tool pin. Material flow patterns predicted by the 2-D simulations (e.g. see Fig. 2) are found to compare favorably with experimental observations (see. e.g. Fig. 3). Simulation results also reveal that material particles tend to pass and get behind the rotating pin from the trailing side, rather than from both sides, of the pin. Possible variations in the material flow pattern due to variations in process parameters are also being investigated.

Student: Shaowen Xu
Advisor: Dr. Xiaomin Deng