Modelling of the bead formation during multi pass hybrid laser/gas metal arc welding

Abstract : A three dimensional finite element model has been developed to simulate weld bead formation in multi pass hybrid laser/gas metal arc welding. The model considers both a gas metal arc welding (GMAW) electrode and a laser beam moving along a workpiece. A Eulerian approach is used in which the interface between the metal and the surrounding gas or plasma is defined by a level set function. Therefore heat transfer boundary conditions are applied through a "Continuum Surface Force" model. An original method has been settled to model material supply. A volume expansion source term is added to the right hand side of the mass conservation equation for certain liquid finite elements in the fusion zone. A compressible Navier Stokes equation is then solved. The new obtained velocity field is used to solve the transport of the level set function for the updating of the gas/metal interface. A new topological reinitialization method has been developed to hold the Eikonal property in the compressible framework of the level set transport. The efficiency of this global model enables to simulate industrial multi pass hybrid welding processes.