Lighter Aircraft May Be Possible With New Hybrid Joining Technique

There has been a lot of excitement at the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research IFAM, located in Bremen, where researchers have been hard at work developing a new, hybrid way to bond lightweight aircraft materials.

Making airplanes lighter is a very important facet of helping them to consume less fuel and so reduce carbon dioxide emissions. Yet what seems easy in theory is not always so easy in practice. Material development has already come a long was and thus far carbon-fibre reinforced plastics (CFRPs) are probably the most popular and common fiber composite plastics currently used in aircraft manufacture. Unlike metal, which can be easily welded, joining DFRP components is not quite so easy. Most often the joining is done mainly with the use of riveting, which causes further problems. The rivet holes reduce the load-bearing capacity of the material and disturb the flow of the forces in the CFRP structures. However it looks as if a new breakthrough in technology may greatly improve the situation. The technology that was recently developed at the institute enables a mixture of riveting and adhesive bonding to be applied to the join accurately and securely. The benefits are obvious: less rivet holes mean a stronger structure and a better flow of forces.

According to Dr. Oliver Klapp of the IFAM, his team has developed a state-of-the art C-clamp riveting machine that accomplishes the joining of these plastic components accurately, automatically and in compliance with current aviation standards. The machine can quickly create only needed rivet holes as well as two-part riveted bolts during the construction process. The ultimate result should be a better all-over distribution of forces. While gluing is known to provide a better distribution of forces, the aviation industry does not rely on this method of joining exclusively for obvious reasons. Klapp does not foresee the disappearance of riveting from the industry altogether in the next few years, the combination of gluing and riveting should provide the ultimate solution until even better materials and methods can be found. The information will be presented at the Composites Europe trade fair to be held in Essen from September 23 to 25 later this year.