Abstract:
|
Friction Stir Welding (FSW) is a relatively new developed solid state joining technique. FSW
process was invented by Wayne Thomas at The Welding Institute (TWI) in December 1991,
and since its invention, it has shown to be viable for joining many kinds of materials of
various thicknesses, including hard-to-weld materials. The main feature of FSW is that the
weld takes place in a solid phase below the melting point of the material to be joined.
In the present study a finite element model of the FSW process is built and a FSW butt weld
of two aluminium alloy 2024-T3 plates is simulated using a fully coupled thermo-mechanical
analysis. Besides the welded panels, the model includes the backing plate and the welding
tool as physical bodies, which makes the simulations more realistic. The model also includes
conductive heat transfer between the contact surfaces of the FSW tool, the aluminium
plates and the backing plates, heat generation due to friction between the tool and the
welded plates and heat loss to the ambient air due to convection.
The simulated model makes it possible to analyse and check several aspects of this welding
technique. It is proved that tool geometry has a vital importance in the FSW process. The
influence of using instantaneous or ramped velocity at the beginning of the simulations is
also studied. Moreover, it is seen that the mesh used in the finite element analysis and the
adjustment of the inelastic heat fraction have a great influence on the obtained results. |