Numerical Simulation Of The Dynamic Process Of Laser-Arc Hybrid Welding

Laser-arc hybrid welding technology is a welding method that utilizes the interaction of laser and arc to enhance the adaptability, which could avoid the defects of the single welding method and have the advantages of energy increased,penetration augmented,stable welding process,assembly reduced,highly reflective materials welding realized and so on. So it has a wide range of applications such as Shipbuilding, Petroleum, Chemical, Electricity, Metallurgy, Automobiles.The process of the hybrid welding is a complex system including heat and mass transfer,metallurgy,mechanics, showing high speed,multi-dimension and multi-parameter. The hybrid welding is under the influence of multi-parameter, such as laser power,arc power,the welding speed,the distance and coupling mechanism of the two heat sources. To control the stability of welding process and get a high-quality welded joint we have to control these factors. As we all know, purely theoretical research can not solve the practical problem and lots of industrial experiments will sharply increase the cost. However, by using numerical simulation technology with certain experiments and establishing hybrid welding mathematical model, we can predict the welding results, achieve the pre-selection and optimization of welding parameters and reduce the number of experiments.The characters of keyhole,laser-induced plasma and coupling mechanism of laser-arc in hybrid welding are deeply analyzed. Based on that, the appropriate three-dimensional finite element model is established according to Exponential Attenuation body heat-source and Elliptical Gauss surface heat-source model. By using ANSYS, the hybrid welding behaviors are simulated. We analyze the characters of laser-TIG hybrid welding according to the computing research of temperature field and flow field. The results of temperature field shows that welding seam is narrow and deep in depth, which means hybrid welding keeps laser welding superior ability to penetrate and the keyhole is not in the center of the heat source but has a extent along the opposite welding direction. The simulation of the welding pool shows that: the surface and bottom of hybrid welding pool separately has two convection ring named Marangoni flow that are caused by the surface tension, which helps to transfer heat around the center of welding pool. The temperature distribution in different distances of two heat sources shows: the distance of laser and TIG arc is not the closer the better but a reasonable distance that can make the process stable and maximize the penetration. Calculated results from the models are found to agree with the experimental results in same welding parameters for the geometry profile of weld, which has also validated the dependability of the above-mentioned model.