Dynamic Behavior of Fused Filament Fabricated Continuous Ramie Fiber-Reinforced Polypropylene Composites under Diverse Loading Conditions

The combination of continuous natural fibers and polypropylene enables the fabrication of environmentally friendly composites with recyclability, light weight, and high strength. Additionally, fused filament fabrication (FFF) 3D printing offers reliable process for efficient customized manufacturing of fiber-reinforced composites. Therefore, this study fabricates continuous ramie fiber-reinforced polypropylene (CRFRPP) composites through the FFF technique. Considering that composites are sensitive to various external conditions such as temperature, loading direction, and loading rate, this work investigates the mechanical behaviors of CRFRPP under a wide range of temperatures and strain rates when loaded parallel and perpendicular to the fiber orientation. The results indicate that the compressive strength of 3D-printed CRFRPP under loading in the parallel fiber direction is higher than that in the perpendicular one. The maximum compressive strength is observed to be 176 MPa at a temperature of −40 °C and a strain rate of 2600 s⁻¹, when loaded in the parallel fiber direction. Under dynamic loading, CRFRPP presents brittle behavior at lower temperatures (−40 and −10 °C) and softening behavior after yielding at higher temperatures (20 and 50 °C). Moreover, the CRFRPP exhibits different failure mechanisms that varied considerably depending on the imposed test conditions.