Investigating the Fracture Resistance of Carbon Fiber-PEEK Composites Produced via Fused Filament Fabrication

The use of carbon fiber-reinforced polyetheretherketone (PEEK) produced through additive manufacturing is crucial due to its exceptional physical and mechanical characteristics, such as its high strength, stiffness, temperature resistance, chemical resistance, lightweight, and biocompatibility. This makes carbon fiber-reinforced PEEK a valuable material in various industries like aerospace, automotive, medical, and electronics. This study investigates the effect of short carbon fibers on the mode-I fracture behavior of PEEK composites made through additive manufacturing. The research employed Fused Filament Fabrication (FFF) to create both short carbon fiber-reinforced and non-reinforced PEEK as the baseline. A compact tension fracture test was conducted to measure the mode-I fracture toughness, and elastic-plastic fracture theory was used to calculate the inter-layer and cross-layer crack growth resistance. Unreinforced PEEK samples showed stable crack growth with significant plastic energy dissipation, whereas short fiber reinforcement resulted in unstable crack growth with subtle plastic energy dissipation. For the examined fiber volume fraction and utilized FFF parameters, the carbon fiber caused a significant decrease in the mode-I fracture toughness of 3D-printed PEEK. The inclusion of fiber reinforcement led to a reduction of approximately 50% in elastic fracture energy and about 80% in total fracture energy. This observation can be attributed to the high fiber volume percentage.