Fast Curing of Adhesives in the Field of CFRP

Abstract

The interest in carbon fiber reinforced plastic (CFRP) structures does not only increase in the area of aircraft construction, but also in the automotive industry. Due to the two-dimensional load transfer adhesive technology offers a particularly high potential of joining structures in lightweight construction. The adhesive systems applied for joining relevant CFRP structures show an insufficient initial strength thus necessitating additional fixing of the components or an accelerated curing of the adhesive. Induction technology has proved to be the most adequate heating technique for fast curing of metal bonds since it achieves high heating rates and enables a drastic reduction of the curing times. Due to their electrical conductivity, CFRP can also be heated by induction. Well-founded studies have been published explaining the physical mechanism behind the generation of heat within CFRP by electromagnetic induction. However, the relation between material and process parameters and the resulting heat generation and temperature distribution in CFRP parts still need to be investigated since, contradictory statements can be found in the literature. A profound knowledge of these relations, though, is elementary in order to predict the heat generation which is necessary to design a safe, fast curing process and to avoid damages to the material. Thus, the fundamental relations existing between the material/process parameters, the heat generation, and the resulting joining characteristics will be verified and discussed.