Joining of intrinsically manufactured frp/metal components to metallic structural elements by resistance spot welding

随着环境和气候保护对交通运输部门的要求不断提高，在开发未来车辆时，轻量化结构越来越重要。最大的轻量化潜力通常出现在复合结构中，其中金属部件与纤维增强塑料部件相结合。由此得到的材料混合物对于接合方法是特别苛刻的。在连接车身结构中的传统钢/钢连接时，主要使用粘合工艺和部件穿透补充元件，例如螺钉和铆钉，或者利用焊接期间部件的可熔性。由于其高度自动化和可实现的周期时间，电阻点焊仍然被认为是车身结构中首选和最突出的连接技术。然而，具有硬质塑料基质的纤维增强塑料不能熔化。此外，随后引入的补充元件破坏了部件的纤维结构，导致整体复合材料的强度降低。使电阻点焊与FRP/金属部件兼容的一种有前途的方法在于将可焊接的载荷引入元件内在地集成到纤维复合材料中。与随后引入的补充元件相比，所谓的插入件可以在不损坏任何纤维的情况下集成，从而充分发挥纤维结构的轻质潜力。本项目将研究复合材料部件制造、伴随的纤维流动和随后的焊接工艺之间的基本关系，以便能够安装可焊接的插入件。应开发一种方法，使用模拟模型以及工艺和部件设计的系统化，以便于在考虑电阻点焊过程中的热引入的情况下组成连接区域。计划的调查应有助于理解可焊接FRP/金属化合物的制造工艺和个性化设计。以使接头具有良好的机械性能以及高的再现性。

In the course of the ever-increasing demands of the environmental and climate protection pose to the transportation sector, lightweight construction is increasingly gaining in importance when it comes to developing future vehicles. The greatest lightweight potential is often found in composite construction where metal components are combined with fiber-reinforced plastic components. The thus resulting material mix is particularly demanding for joining methods. When joining conventional steel/steel connections in vehicle body construction, adhesive processes and component-penetrating supplementary elements, as for example screws and rivets, are primarily used or the fusibility of the components during welding is harnessed. Because of its high degree of automation and its achievable cycle times, resistance spot welding is still considered the preferred and most prominent joining technique in vehicle body construction. However, fiber reinforced plastics with a duroplastic matrix cannot be melted. Furthermore, a supplementary element which is subsequently introduced destroys the component’s fiber architecture, resulting in a reduction of the strength of the overall compound.A promising approach of making resistance spot welding compatible with FRP/metal components consists in intrinsically integrating weldable load-introducing elements into the fiber composite. In contrast to supplementary elements introduced subsequently, the so-called inserts may be integrated without damaging any fibers thereby allowing to exploit the full lightweight potential of the fiber structure.This project shall examine fundamental correlations between the manufacture of composite components, the accompanying fiber flow and the subsequent welding process in order to be able to install weldable inserts. A method shall be developed, using simulation models and the systematization of process and component design to facilitate the composition of the joining area under consideration of heat introduction during resistance spot welding.The planned investigations shall make a significant contribution to understanding the manufacturing process and the individual design of weldable FRP/metal compounds, in order to enable good mechanical properties of the joint as well as high reproducibility.