Induction Welding of CFK

Continuous induction welding is considered to be one of the most promising methods for thermal joining of CFRTP. A major challenge of induction welding is the complex temperature distribution in the joining zone and a lack of efficient and accurate models to calculate the temperature distribution. In order to establish a basis for the simulation of continuous induction welding, analytical as well as numerical models for the description of the static heating behavior of CFRP laminates were created and extensively validated in previous project phases. On this basis, a simulation model for the induction welding process has been developed in the final
phase of the project. By contrast to conventional coupled multiphysics simulations, the electro-magnetic
calculation of the heating pattern is performed only once in an upstream simulation. The resulting heating pattern is then integrated as a boundary condition into a thermal-mechanical simulation of the induction welding process. The developed simulation approach was comprehensively validated by means of induction welding experiments. The simulation model has proven to be capable of accurately predicting the temperature distribution in the joining partners. In contrast to previous models, the decoupled calculation method – which for the first time allows the efficient use of high-resolution material models even for large welding geometries – is
able to calculate the influence of different laminate layups on the temperature distribution. Planned next steps include not only the simulation of complex demonstrators with several welding paths, but also the coupling of the simulation to an in-situ process control.

The long-term objective is to increase the process speed of the continuous induction welding process of CFRP organo sheets in connection with a resulting joining quality at autoclave level.