A multi-physics level set approach for the simulation of the hybrid Laser/GMAW process

Olivier Desmaison (1) , Gildas Guillemot (1) , Michel Bellet (1)

1 CEMEF - Centre de Mise en Forme des Matériaux

A new hybrid welding technique has recently been developed in order to answer to the industry needs to gather high thickness steel sheets. The combination of a laser beam and a gas metal arc enables to develop welds with a high added metal rate and low porosity. Moreover lower deformation and residual stresses are observed after cooling. Nevertheless the mastery of this technique is still in development due to the various physical phenomena which occur and interact during the welding process. A three dimensional finite element model has been developed to simulate this welding process. Metal and air gas domains are both meshed. A Eulerian-Lagrangian approach is used in which the interface between the metal and the surrounding air or plasma is defined by a level set function. Fluid flow phenomena and temperature evolution in the weld pool are simulated. Two moving heat sources are considered at the surface of the metal. As the arc plasma and laser beam are not modeled in the level set framework, the 'Continuum Surface Force' approach is used: a volumetric heat source distribution is applied to the immediate neighbourhood of the interface. The added metal represents an additional heat source. The Navier-Stokes equations are solved in the weld pool regarding the surface Marangoni force, the volumetric buoyancy. After solving the momentum conservation equation, metal / air interface is tracked through the resolution of a convection equation with the calculated velocity field as input. As the hybrid welding technique is usually a multi-pass process applied on high thickness piece with high chamfer, it is of primary importance to develop a correct modeling of solid / solid contact interfaces. It is shown that the present level set approach coupled with an adaptative remeshing tool enables to follow these interfaces to simulate the entire process steps. Weld geometry on a specific steel alloy is shown and compared to the expected result.

Domaines: Matériaux

Olivier Desmaison, Gildas Guillemot, Michel Bellet. A multi-physics level set approach for the simulation of the hybrid Laser/GMAW process. GMAW process, 10th International Seminar on Numerical Analysis of Weldability, Sep 2012, Seggau, Austria. pp.725-736. ⟨hal-00983373⟩