Graphene, in combination with carbon fibers and epoxy, will be used for a demonstration of new functions for highly stressed composite airframe structures. The demonstrators are mechanical joints using fasteners (bolted joints) and composite parts. The bolted joints are designed and manufactured for improved mechanical strength, damage tolerance and electrical conductivity when compared with technical solutions used today and they are representative for primary structure where 20 % weight reduction is a realistic target.
Weight savings are possible due to improved efficiency joints (improved bolt bearing strength), reduced laminate moisture absorption and improved electrical conductivity, which will reduce the current need for metals used for lightning strike protection and other electrical functions such as shielding and connectors.
Tests with 5 and 25 micrometer graphene flakes dispersed in flight qualified 2 component epoxy have shown that the process we will use works well regarding both manufacturing and laminate quality. Graphene is used in epoxy for wet impregnation of carbon fiber fabric at a relatively high content. Targeted graphene volume content is above 2 % by volume and where it is feasible, carbon nanotubes will also be used.
In the Saab demo, the impregnated fabric will be combined with carbon fiber/epoxy prepreg according to modelling and simulations to be carried out by Chalmers. The Saab design is representative of a next generation passenger Aircraft. The Blackwing design represents a sports aircraft. The poor bolt bearing strength of carbon fiber epoxy composites is a limitation for aeronautic applications today and also for other markets where assembled composite structures are used. The potential for graphene may be very large.
Professor vid Chalmers, Industrial and Materials Science, Material and Computational Mechanics
Funding Chalmers participation during 2017–2019
Areas of Advance