Investigation of mechanical properties of fused deposition modeling manufactured PLA, PAHT-CF15, and PLA/PAHT-CF15 composites under accelerated aging

In this study, changes in mechanical properties after UV aging were investigated to understand the resistance to environmental factors of single and multi-material structures produced using the Fused Deposition Modeling (FDM) method. Within the scope of the study, filaments commonly used in the FDM technique; PLA+, high-performance carbon fiber reinforced Polyamide (PAHT-CF15), and structures formed by the combination of these two materials, referred to as MIX in the study, were examined. In the experimental design, specimens were produced with different wall counts (2, 3, 4) and different infill densities (%25, %50, %75, %100). While one group of the produced specimens was designated as the reference and not subjected to aging, the remaining specimens were subjected to an accelerated UV aging process for 168 hours at an ambient temperature of 70 °C under UVA-340 lamps, based on ASTM G154 and ASTM D4329 standards. Tensile, three-point bending, and hardness tests were performed on the reference and aged specimens, and mass changes were analysed. The obtained results showed that the increase in wall count and infill density increased the mechanical strength in all material structures. While the mechanical properties of PLA+ specimens did not change significantly after aging; the mechanical performances of PAHT-CF15 and MIX structures improved after the aging process. In particular, it was observed that the tensile strengths of MIX structures improved due to the effect provided by the carbon fiber reinforced outer walls, and their bending performances were better than that of PAHT-CF15. The study results demonstrated that MIX structures produced using appropriate parameters in 3D printers can be an alternative to their constituent PLA+ and PAHT-CF15 materials in terms of both economic and mechanical performance.