Polymer composites have been widely used in load-bearing components of aircraft such as wings, ribs, and frames, due to their good chemical corrosion resistance and plastic formingability. They have achieved the goal of lightweight design. In addition, their unique properties such as resistance to high and low temperatures, fatigue, and hydrolysis have made them widely used in fields such as radar antenna covers and fastening systems.
With the development of the integration of structure and function in the new generation of weapons and equipment, polymer composites and their products have broken through the application limitations of traditional metallic materials and even produced revolutionary effects while improving performance. Moreover, the application level of polymer composites and their products has always been an important indicator of equipment advancement. The development of polymer composites in the aviation field has roughly experienced four stages, from secondary load-bearing components to tail level primary load-bearing components, to wings, and finally to primary load-bearing components of the fuselage. It has gradually shifted from small components to large core components and from military to civilian use.
Polyether ether ketone (PEEK) thermoplastic materials can provide excellent comprehensive performance in a broad temperature range and under extreme conditions, making it the most popular high-performance engineering plastic today. Many classic cases of alternative traditional metal materials have emerged in the aerospace field, achieving surpassing traditional aluminum in design freedom, manufacturing efficiency, structural lightweighting, and reliability. PEEK composite materials, once introduced, have been used as military materials in the aerospace field and can replace aluminum and other metal materials for manufacturing various components.
The comparison of the specific strength of PEEK composites and other commonly used aviation metals reveals that short-fiber-reinforced PEEK composites have higher strength and stiffness. The comparison of the tensile fatigue performance of PEEK materials and aluminum shows that the fatigue life of PEEK composite material is 100 times longer than that of typical aviation aluminum alloys. Initially, PEEK materials were used for brackets, clips, clamps, connectors, fasteners, and other system attachments. The most common method now is fiber reinforcement. A large number of studies have found that PEEK composite material reinforced with glass fiber, carbon nanotubes, and carbon fiber have significantly improved mechanical and thermal properties. Fiber-reinforced PEEK materials have gradually begun to be used in primary load-bearing components.
In addition, a high modulus carbon fiber-reinforced PEEK composite material is used for Airbus A350 to A900 aircraft door components. By using this material, drilling can be easily done, reducing weight by 40% and saving costs by 40%. PEEK pipes have been designated for use in the cargo drain system of Airbus A350XWB. In the aerospace field, glass fiber-reinforced PEEK composite material has been successfully applied to satellite lithium battery parts and high-temperature insulation rings.