New strategy of solid/fluid coupling during numerical simulation of thermo-mechanical processes

Abstract

In this study, numerical methods are developed to simulate thermomechanical processes, taking into account both the fluid flows in the molten pool and the deformations of the solid parts. The methods are based on a new strategy of solid/fluid coupling. They allow to simulate the formation of the molten pool by taking into account the fluid flows through both effects of the surface tension ("curvature effect" and "Marangoni effect") and the buoyancy. An ALE approach is used to follow the evolution of the free surface. The effects of the deformations in the base metal on the fluid flows in the molten pool (solid/fluid interaction) is ensured by imposing the velocities of the solid nodes during the thermo-fluid simulation. As an application, a thermo-fluid-mechanical simulation of laser welding is carried out. It is found that the solid/fluid interaction has a minor effect on simulation results.

Numerical Simulation of the Molten Pool of a Powder Bed

“…In the powder bed as well as the substrate, the element size is 45 µm. An equivalent ellipsoidal heat source [3] [9] is applied in the melt direction to carry out a single track with a building speed of 500 mm.s −1 . The laser power density of 6500 MW.m −3 is applied (with a maximal front source intensity of 1600 and a maximal rear source intensity of 1500).…”

“…These fluid flows are generally taken into account during the microscopic and mesoscopic simulations. Indeed, the aim of these two simulations is to consider the physical phenomena involved by the process itself [2], [3]. However, the complexity of the modeling of these phenomena makes the computation time very important especially for the microscopic simulation [4], [5], [6].…”

A Temperature-Dependent Heat Source for Simulating Deep Penetration in Selective Laser Melting Process

“…The multi-physical models aim to compute more accurately the thermal and velocity fields by couplings of different scales of physics interactions, such as interactions between an electron or laser beam and powders [3], couplings between fluid and solid [4], etc. Numerous high-fidelity multi-physical models [5][6][7][8][9] have been proposed to model the realistic melting surface of the powder layer by tracking the solid-gas interface.…”