Title: Fastening Aerospace Structures with Carbon Fiber/Polyether Ether Ketone Composite Rivets
Authors: Christophe Absi, Nawaf Alsinani, Louis Laberge Lebel
Abstract: High specific properties make composite materials desirable for modern aerospace applications. However, joining such materials presents new challenges. Notably, composites are not capable of supporting the high localized loads caused by deforming aluminum solid rivets, traditionally used for joining aluminum structures. Instead, metallic bolt-type fasteners are used. However, such fasteners present drawbacks regarding their weight, lightning strike hazards, corrosion, and cost. We present here the development of an innovative assembly technology to overcome these downfalls, with carbon fiber/thermoplastic composite rivets. First, carbon fiber/polyether ether ketone (CF/PEEK) rods are pultruded and cut into short length blanks. Then, by Joule effect, the blank is heated above the melting temperature of the thermoplastic matrix. Next, it is molded in situ, i.e., into steel or carbon fiber reinforced polymer (CFRP) adherends. To ensure consistency, the riveting process is performed by an automated machine. In steel, up to 175 W of heating were applied, while only 110 W were used for CFRP plates. The riveting process required 35 s. Shear and tension test results showed higher specific properties than similar joints featuring aerospace-grade titanium fasteners. CF/PEEK rivets submitted to shear held 9 kN/g, while titanium fasteners held 5 kN/g. For samples submitted to tension, CF/PEEK rivets held 5.6 kN/g, while titanium fasteners held between 3 kN/g and 5.5 kN/g. These superior specific mechanical properties show that the technology could be used in the next generation of lighter and safer aircraft structures.
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Conference: SAMPE NEXUS 2021
Publication Date: 2021/06/29
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