Product Code: ICAL05_1006

Numerical Modeling of Molten Pool Formation During an Interaction of a Pulse Laser (Nd:YAG) with an Aluminum Sheet
Authors:
Nicolas Pierron, LTm - IUT Le Creusot; Le Creusot France
Presented at ICALEO 2005

In this paper a numerical modeling of molten pool during laser processing is presented. A 2D model is implemented in the finite element software Femlab. This study presents the first results obtained for aluminum sheets. Because of the laser power density and localized laser heating, high temperature gradients are produced. Consequently, a numerical approach in order to establish a model for such phenomena is often complicated but useful. A very fine mesh is realized in the interaction zone between laser beam and work piece. The variations of thermo physical characteristics with temperature induce several no-linearities. The latent fusion heat is introduced like a source in the Fourier equation. An additional term in momentum equation represents the resistance to the flow of liquid through the mushy region. It is derived from Darcy relation. Marangoni flow, which is induced by the surface tension gradients along the melted pool surface, has effects on the shape of the molten pool. This flow dominates the transport of thermal energy in the liquid. A recoil pressure, caused by aluminum evaporation, deforms the free surface. This one is depressed at the centre and convex near the edge of molten pool. The free surface deformation is controlled by an ALE formulation which allows realizing an adaptation of calculated mesh at different interface positions. Simultaneously, observations by SEM were used to characterize and to compare the theoretical melting pool geometry with the experimental values.