Fastening Composite Structures Using Carbon Fiber/Polyetherimide Rivets

Abstract

To reduce aircraft weight, composite materials are used for their high specific properties. Joining these composite components brings new challenges, since the matrix cannot support the high located loads during the deformation of a metallic rivet, traditionally used to joint metallic structures. Mechanical fastening using titanium bolts is the most used joining method in the aerospace industry. However, this solution presents many drawbacks with regards to its weight, lightning strike hazard, risk of water penetration and cost. To overcome these problems, an innovative assembly technology using carbon fiber/thermoplastic composite rivets was developed. It was previously demonstrated with Carbon/Polyamide (C/PA) rivets. These rivets are heated, using Joule effect, above the melting temperature of the thermoplastic resin. They are then molded in situ, i.e, into the laminates to be joined. The materials similarity eliminates the galvanic corrosion and the electromagnetic shielding issues. To ensure a constant quality for an industrial application, the riveting technique is automated. The riveting parameters are controlled to ensure the joint quality and repeatability. Carbon fiber/polyetherimide (C/PEI) blanks manufactured using pultrusion were used to join carbon/epoxy laminates. The mechanical testing showed that the mechanical properties of the composite riveted joint with C/PEI rivets are higher than those riveted with C/PA rivets. With these advantages, the technology could be applied in the next generation of aircraft structures.