Numerical Analysis Of The Forced Vibration At A Pulsed Twin-Wire Gmaw Weld Pool’s Free Surface

In order to study the forced vibration phenomena at a Pulsed Twin-wire GasMetal Arc Welding (Twin-wire GMAW) weld pool, a two-dimensional transientnumerical model is established to describe the wave behavior of the weld pool’s freesurface, and then a detailed analysis of the dynamic behavior of the Pulsed twin-wireGMAW weld pool’s free surface is carried out.Based on the analysis of the impingement on weld pool surface by periodicallytransferred droplets, a transient mathematical model is presented to investigate theforced vibration and its resulted wave behavior at the weld pool’s free surface inaccordance with the two-dimensional wave theory. The governing differentialequations are built and their corresponding initial conditions and boundary conditionsare given. Furthermore, the governing equations are discretized, and calculationsoftware is developed in FORTRAN.By using the two-dimensional transient model, numerical analysis of the dynamicwave behavior of the weld pool’s free surface are performed. The vibration and waveat the weld pool’s free surface that caused by he periodically transferred droplets arepredicted, and then transient profiles of weld pool’s free surface are obtained. First, thephenomena of the forced vibration resulted by transferred droplet only from the frontwire at a Pulsed twin-wire GMAW weld pool’s free surface are studied, and theexisting time of wave at weld pool’s free surface by the transferred droplet during adroplet transfer period is predicted, which agrees well with the measured result. Then,wave behavior of free surface in a Pulsed Twin-wire GMAW weld pool are calculated,and the transient distribution of displacement and moving velocity of weld pool’s freesurface are achieved. While the spreading velocity and period of wave are predicted,the interference phenomenon between the two wave sources on weld pool surface is studied. Finally, the dynamic behaviors of weld pool’s free surface in Pulsed Twin-wireGMAW under conditions of different droplet diameter and different droplet transferfrequency are obtained, therefore the transient wave pattern and variation tendency ofdisplacement and velocity of weld pool’s free surface are reconstructed.This study aims to provide basic data and theoretical instruction for theindustrialization production of the Pulsed twin-wire GMAW and the optimization ofwelding parameters.