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

对于铝和铜的焊接，激光激活TIG焊(LATIG)是一种合适的工艺。它基于激光辐射和电弧的协同作用，与这两种工艺的单独使用相比，提供了特别高的熔化效率。导致熔化效率提高的物理现象及其相互作用还没有得到充分的了解。初步分析认为，固体激光辐射对TIG焊接过程的影响并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，将开发一个过程模型，并将其用于数值实验，以分析激光对铝和铜熔化效率的影响。在考虑激光诱导蒸发的情况下，主要考虑阳极套的现象，金属蒸气射流的形成及其对电弧等离子体的热、气动力和电磁特性的影响，以及对熔池表面的电流密度、热流密度和压力分布的影响。借助于该模型，可以研究这些相互作用的因果链，并可以评估不同相互作用的作用。特别关注的是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的影响及其与工件表面的相互作用。另一方面，该模型考虑了激光蒸发(对流蒸发方式)对阳极边界层的影响，重点研究了熔池自由面的动力学、熔池内的传热、流体力学和电磁过程。对LATIG工艺的广泛了解和理解使我们能够制定建议，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.