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Simulation of Laser Welding with SPH and a Ray-Tracing Scheme

Simulation of Laser Welding with SPH and a Ray-Tracing Scheme

Datum: 14. Dezember 2017 16:00

Ort: Allmandring 3, Seminarraum 1.079

Veranstalter: ICP

Simulation of Laser Welding with SPH and a Ray-Tracing Scheme

Peter Eberhard, Institut für Technische und Numerische Mechanik, Universität Stuttgart

Laser welding is an established joining technique, but not all physical phenomena that occur during the welding process are completely understood. Multi-physics SPH simulations are a helpful tool to gain insight into this complex process. The main challenge is the coupling of the thermo-mechanical problem with the fluid flow in the transient weld pool or even the gas flow of the evaporated material.

The SPH method is applied for modeling both solid and liquid phases of the workpiece. The solid material is considered to be thermoelastic with thermal expansion. For the liquid phase, temperature-dependent surface tension has a major contribution. All phase transitions occur adapted from the enthalpy values of the particles. At high intensities of the laser beam, the laser radiation causes instantaneous evaporation of the material such that a capillary is formed in the so-called deep penetration welding. The gas phase is only included through recoil pressure on the melt flow. Depending on the chosen laser power and absorbed intensity, the laser-material interaction is either modeled with heat source particles at the surface or by applying a ray-tracing scheme that tracks the laser beam inside the capillary based on geometrical optics. The latter approach allows to track the formation and evolution of the capillary during deep penetration laser welding.

By comparing simulation results to experimental data, we observe that the model is able to capture main characteristics of the welding process.

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