Numerical simulation of laser keyhole welding processes based on control volume methods

The control volume method (CVM) is the basic technique of computational fluid dynamics, a mathematical model for the simulation of keyhole and pool formation during deep penetration laser beam welding. Using CVM is different from using the finite element method. A three-dimensional volumetric heat source model consisting of a rotary Gaussian volumetric heat source and a double ellipsoid heat source is developed. Taking into account buoyancy and gravity, SIMPLE solution and first order upwind discretization under-relaxation iteration are used. The modelling is carried out for Ti-6Al-4V in laser keyhole welding using CVM. The local temperature distribution in the fusion zone is simulated separately with regard to dependence on laser power inputs and welding speeds. The results indicate that eddies occur near the top and bottom surfaces and help heat transfer and bulbous weld pool formation. To assess the accuracy of the developed model, the computed and experimentally determined pool shapes of laser keyhole welding are compared for welds on titanium alloys.