PSI - Issue 72

Miloš Vorkapić et al. / Procedia Structural Integrity 72 (2025) 470 – 478

471

Keywords: polylactic acid; carbon fibers; mechanical resistance; thermal resistance; additive manufacturing

1. Introduction High demand for lightweight yet strong materials for various industries encourages the development and research of advanced composites and composite filaments intended for additive manufacturing. Carbon fiber-reinforced polylactic acid (PLA) composites, PLA/CF, have emerged as a promising material, balancing sustainability, printability, and exceptional mechanical performance. The integration of carbon fibers into the PLA matrix would not only enhance the material’s stiffness and strength but also mitigates the inherent brittleness of pure PLA, expanding its applicability beyond conventional uses. Additive manufacturing (AM) represents a revolutionary advancement compared to traditional production methods. Its key advantage lies in the ability to fabricate highly complex parts without unnecessary operations and the use of specialized tools and accessories. Fused Deposition Modeling (FDM) is an AM technique in which the model is built layer by layer. The AM process encompasses design, 3D printing, and final realization of the model. 3D printing technology offers flexibility for manufacturing complex structures with tailored mechanical properties. In this study, a PLA composite reinforced with carbon fibers (PLA/CF) was used. PLA is a commonly used biodegradable polymer, and carbon fiber (CF) reinforcement improves its mechanical and thermal properties. The neat polymer PLA is known for several advantages over other additively manufactured thermoplastic materials with FDM technique, like for the highest stiffness values and high flexural strength, Milovano vić et al. (2024) . Recently, there have been studies conducted on possible reinforcement of PLA filaments for 3D printing, by introduction of various additives, Magri et al. (2021), Limpas et al. (2024), Plamadiala (2025), Tripathi (2021), and Ogaili et al. (2024). The objective of this study is to investigate the thermo-mechanical performance of additively manufactured PLA-carbon fiber composites (PLA/CF), with a focus on tensile strength, impact toughness, hardness, and thermal resistance, in relation to 3D printing orientation. This material is particularly suitable for structural components such as brackets and various frames, Wang et al. (2024). Additionally, it is widely employed in manufacturing components for drones, automobiles, and aircraft, especially in applications where weight and strength are critical factors, Al Zahmi et al. (2022). The PLA/CF composite is expected to exhibits enhanced mechanical properties, including increased Young's modulus and tensile strength, compared to neat PLA, due to the incorporation of carbon fibers, Oksman et al. (2023) and Magri (2021). Consequently, its primary application is the production of parts with superior strength without increasing their weight. One of the key distinctions between pure PLA and PLA/CF composites is the required heater temperature, ensuring the molten filament flows smoothly through the nozzle. The nozzle temperature for PLA/CF is higher than that of pure PLA, Li et al. (2018). Research by Jamadar et al. (2024) demonstrated that PLA/CF composites exhibit superior fatigue resistance compared to PLA, ABS, and ABS/CF samples. Furthermore, PLA reinforced with carbon fibers ie expected to show excellent stiffness and durability, which depend on parameters such as infill density, infill pattern, printing direction, and layer thickness, as reported by Milovanović et al. (2024), Ferreira et al. (2017) and Ansari et al. (2022). A comparison of pure PLA and PLA/CF composites revealed that at an infill density of 90%, a layer height of 0.1 mm, and a low printing speed of 30 mm/s, the tensile properties of PLA/CF were significantly superior to those of PLA, Pazhamannil et al. (2024). By systematically analyzing the influence of printing orientation and temperature on the mechanical resistance of PLA/CF, this study contributes to the development of high-performance, fiber-reinforced composites and provides valuable insights into their potential for next-generation lightweight structural components. 2. Material and Methods A total of 54 samples were fabricated — 27 for the bending test and 27 for the Charpy impact test. The material used was PLA/CF matte black filament with a diameter of 1.75 mm, manufactured by Bambu Lab. The essential properties of this material are listed in Table 1. The 3D printing process was conducted using the Bambu Lab X1 Carbon printer, a next-generation FDM printer offering high-resolution printing and an integrated Lidar (Laser Imaging Detection and Ranging) system to enhance adhesion and overall print quality. This printer supports various filament types, including