Self-consistent modelling of Laser- Activated -TIG (LATIG) welding of Aluminium or Copper

对于焊接铝和铜，激光激活TIG焊接（LATIG）代表了合适的工艺。它基于激光辐射和电弧的协同作用，与单独使用这两种工艺相比，具有特别高的熔化效率。物理现象和它们之间的相互作用是提高熔化效率的原因，但人们还没有充分了解。从初步分析可以得出结论，固态激光辐射对TIG焊接过程的影响不是由于激光辐射与电弧等离子体的直接相互作用而获得的，而是需要考虑对工件表面的影响。因此，在本项目中，将开发、实施并用于数值实验的过程模型，以分析激光对铝和铜熔化效率的影响。要考虑的主要现象是考虑激光诱导蒸发的阳极鞘，金属蒸汽射流的形成及其对电弧等离子体的热、气体动力学和电磁特性的影响，以及对焊接熔池表面上的电流密度、热流和压力分布的影响。借助这种模型，可以研究这些相互作用的因果链，并可以评估所区分的相互作用的作用。特别关注的是一方面的金属蒸汽射流的形成对电弧等离子体的热，气体动力学和电磁特性及其与工件表面的相互作用的影响。另一方面，该模型侧重于动态的焊接池自由表面，传热，流体动力学和电磁过程中的焊接池考虑到激光蒸发（蒸发对流模式）的金属阳极边界层的影响。对LATIG工艺的深入了解和理解使我们能够提出建议，以实现铝和铜焊接的高生产率和工艺稳定性。

For welding Aluminum and Copper, laser activated TIG welding (LATIG) represents a suitable process. It is based on the synergetic interaction of laser radiation and arc and offers a particularly high melting efficiency compared to the individual use of both processes. The physical phenomena and their interactions that are responsible for the increase in melting efficiency are not yet sufficiently understood. From a preliminary analysis it can be concluded that the influence of solid-state laser radiation on the TIG welding process is not gained due to a direct interaction of the laser radiation with the arc plasma but that the effects on the work piece surface needs to be considered. Therefore, in this project, a process model will be developed, implemented and used for numerical experiments, in order to analyse the influence of the laser on the efficiency of melting in the case of aluminium and copper. The main phenomenon to be taken into account is the anode sheath with considering the laser-induced evaporation, with the formation of a metallic vapour jet and its influence on the thermal, gas-dynamic and electromagnetic characteristics of the arc plasma, as well as on the current density, heat flux and pressure distributions on the weld pool surface. With the help of such model, the cause and effect chain of these interactions can be investigated and the role of the distinguished interactions can be evaluated. Special focus lies on one side on the effect of the formation of a metallic vapour jet on the thermal, gas-dynamic and electromagnetic characteristics of the arc plasma and its interaction with the work piece surface. On the other side, the model focusses on the dynamics of the weld pool free surface, heat transfer, hydrodynamic and electromagnetic processes in the weld pool taking into account the effects of laser evaporation (convective mode of evaporation) of metal on the anode boundary layer. The extended knowledge and understanding about the LATIG process allow the development of recommendations to achieve the high productivity and process stability for welding aluminium and copper.