Focused Heat Generation in Weld Zones of Common Carbon Fiber Laminates by Induction

Kurzfassung

Research is done into alternative composite joining techniques, as contemporary methods require extensive work. The application of induction welding, one of the three most researched composite welding techniques, results in less labour and defects compared to mechanical fastening. The downside of induction welding is that the heating rate is reciprocal to the distance between carbon fibres and inductor and thus the weld zone cannot be heated exclusively. As a yielding surface leads to an imperfect weld, the aim of this research was identifying induction heating techniques to selectively heat the weld zone, such as manipulation techniques of the magnetic field and application of CFRP susceptors. A dependency of the heating rate on the orientation of the magnetic field was discovered, which can indeed be used to selectively heat plies in a specific orientation within the laminate. Furthermore, It was shown that susceptors made of carbon fiber can increase the temperature at the weld zone. While further research has to be done, an increase of the heating benefit they deliver could enable them to be used for more efficient welds in the future. Finally, a verification for lightning strike protection (LSP) was performed by clamping LSP onto the test parts. The heat generated in CFRP joining partners went down when the LSP was added. No peak temperature was measured at the side of the LSP.