Influence of infill patterns and densities on the fatigue performance and fracture behavior of 3D-printed carbon fiber-reinforced PLA composites

This paper studied the mechanical properties of carbon fiber-reinforced polylactic acid (CF-PLA) samples manufactured with three different 3D-printed patterns: gyroid, tri-hexagon, and triangular. Filler content was generated in the samples at infill ratios of 30%, 60%, and 90%. Conventional tensile, flexural, impact, and fatigue tests were conducted to investigate the mechanical properties. It was found that the gyroid infill pattern enhanced performance, exhibiting tensile strength and modulus of elasticity up to 63% and 13% greater, respectively, than the tri-hexagon pattern at a 90% infill ratio. The fatigue life improvement was 113% compared with the tri-hexagon pattern. The tensile strength and modulus of elasticity increased up to 35% and 40% after including carbon fibers. The increase in flexural modulus was 30% compared to the triangular pattern, whereas impact energy absorption reached the best result with the triangular pattern, up to 89% more than the gyroid pattern. These results elucidate the optimization of infill patterns and ratios together with carbon fiber reinforcement for the development of CF-PLA components as a high-performance 3D printing solution for a wide range of engineering applications.