Numerical simulation onto the preliminary period of Friction Hydro Pillar Processing in Friction Stitch Welding

Numerical simulation technology by Finite Element Method (FEM) based on solid mechanics is adopted to study the contact properties of Friction Hydro Pillar Processing (FHPP) at its preliminary period during the process of Friction Stitch Welding (FSW). The analysis through three dimensional elastoplastic static FEM model indicates that the normal stress on the contact interfaces increases gradually along the radial direction from center to the outside, and the metal stud will become thickening when the applied external load approaches to a certain value. The analysis through three dimensional thermal mechanically coupled FEM model indicates that the temperature on the contact interfaces increases rapidly, but the highest temperature value during the whole process is lower than the melt point of metal involved. As to the normal stress distribution, it is relatively high at the marginal node while relatively low at the central node, and the normal stress will decrease gradually with the elapse of time.