Fatigue behavior and failure mechanism of 3D-printed continuous glass fiber-reinforced PLA composites under rotating bending fatigue

This study investigates the fatigue behavior and failure mechanisms of 3D-printed polylactic acid (PLA) composites reinforced with continuous glass fibers under rotating bending fatigue. Composite specimens were fabricated using a modified fused deposition modeling (FDM) printer with fiber volume fractions of 16%. Fatigue testing was conducted under fully reversed loading at room temperature, and fracture surfaces were analyzed using field-emission scanning electron microscopy (FE-SEM). Results indicate that fiber reinforcement significantly enhances fatigue resistance, with fiber orientation (+45/-45) and infill density playing critical roles in improving performance. A Poisson regression model confirmed the statistical significance of all main effects and two interactions, with print direction having the greatest influence. Fractographic analysis revealed void, fiber breakage, and fiber-matrix debonding as key failure modes. The study provides crucial insights for optimizing composite materials for applications involving cyclic loading.