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Gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) have been widely used as a joining method in every industrial sector. Due to the complexity of welding processes, the trial and error method is still used by welding engineers to solve welding problems and find optimal welding parameters. Modeling transport phenomena in welding processes can provide insights to the welding processes and enable welding process parameters optimization.
We have developed several models to simulate the arc plasma, electrode melting, droplet formation and detachment, droplet transfer in the arc, droplet impingement on to the weld pool, weld pool dynamics and solidification. We will continue to develop and improve these models and use the developed models to investigate welding physics, weld defects formation mechanisms, and create innovative methods to control welding processes and improve weld quality.

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Fig. 1 Simulation results of an axisymmetric arc: (a) temperature distribution; (b) velocity distribution; (c) Electrical potential distribution.

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Fig. 2 Simulation results during droplet formation: (a) Temperature; (b) Velocity; (c) Electrical potential; (d) Current density; (e) Electromagnetic force.

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Fig. 3 Arc plasma distortion under the influence of the detached droplet and the deformed weld pool.

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Fig. 4. One droplet per pulse (ODPP) is achieved by optimizing pulsed current parameters.

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Fig. 5 A sequence of temperature distributions in the metal showing droplet generation, detachment, transfer in the arc, impingement onto the weld pool, and weld pool dynamics.

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Fig. 6 Partial view of the three-dimensional mesh system showing ripple formation.

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Fig. 7 Droplet impingement onto weld pool in a three-dimensional welding.