Residual stiffness and strength analysis of fatigue behavior in a 3D-printed honeycomb structure of continuous glass fiber-reinforced polylactic acid (PLA) composite

This study investigates the fatigue behavior of composite honeycomb structures fabricated using the fused filament fabrication (FFF) technique with a polylactic acid (PLA) matrix and continuous glass fiber reinforcement. Fatigue testing was conducted at stress levels of 55 %, 65 %, and 75 % of the ultimate tensile strength (UTS) to develop S-N curves. All samples were fatigue tested in cyclic tension with a load ratio of R = 0.05. Additionally, the residual stiffness and residual strength of the honeycombs were evaluated at 30 %, 60 %, and 90 % of their average fatigue life. Results indicate that incorporating continuous glass fibers significantly enhances the fatigue life of the PLA honeycomb structures under cyclic tension loading. The fracture surfaces of the specimens were analyzed using scanning electron microscopy (SEM), revealing failure modes similar to those of traditionally manufactured composite honeycombs. The study underscores the potential of FFF in producing engineered composite honeycombs with superior fatigue properties, making them suitable for various high-load applications. The findings also highlight the importance of understanding the residual mechanical properties to predict the long-term performance and reliability of these materials in practical applications.