Investigation of Mechanical Performance of Carbon Fiber Powder-Reinforced Composites through SLA-Based Additive Manufacturing

Abstract

This study investigates the mechanical performance of carbon fiber powder (CFP)-reinforced photopolymer composites fabricated through stereolithography (SLA)-based additive manufacturing. Composite specimens containing 0-0.5 wt% CFP were fabricated and evaluated through tensile, hardness, surface roughness, SEM and particle analyses. The incorporation of CPF significantly improved the mechanical properties of the printed composites. The highest tensile strength of 13.04 MPa was achieved at 0.375 wt% CFP loading (S4), representing a substantial improvement over the neat resin specimen (5.83 MPa). Maximum hardness (58 HD) and the lowest surface roughness (Ra = 2.66 μm) were obtained at 0.5 wt% CFP content (S5). SEM and particle analyses revealed that excessive reinforcement promoted brittle fracture characteristics, internal cracking and increased surface irregularities. Overall, CFP contents between 0.25 and 0.375 wt% provided the best balance between strength, hardness and ductility. These findings demonstrate the potential of SLA-fabricated CFP composites for lightweight engineering and functional structural applications.

Conclusion

This study systematically investigated the effect of CFP concentration on the mechanical, surface and microstructural behavior of SLA 3D-printed photopolymer composites. The results demonstrated that CFP content plays a critical role in governing the balance between strength enhancement and structural integrity. Tensile analysis revealed that an intermediate reinforcement range of 0.125-0.25 wt% (S2-S3) provides the most balanced performance, achieving tensile strength of 10.28-11.82 MPa and higher ductility of 14.34-16.57%, along with maximum load capacity up to 565.72 N. In contrast, higher CFP loadings (S4-S5) increased tensile strength up to 13.04 MPa but resulted in reduced strain (9.71-12.41%), indicating increased brittleness and reduced plastic deformation capability. Hardness results showed a continuous improvement with increasing CFP content, rising from 47.50 HD (S1) to 58.00 HD (S5), confirming enhanced surface resistance due to reinforcement effects. Surface roughness analysis indicated a non-linear trend, where the highest fiber loading (S5) achieved the lowest Ra value (2.66 μm), suggesting improved surface smoothness; however this was accompanied by evidence of subsurface structural damage. SEM and particle analysis further confirmed that low reinforcement levels promote uniform particle distribution and stable microstructure, whereas higher CFP concentrations induce microvoids, uneven layer formation, brittle fracture features and internal cracking. Notably, S1 exhibited homogeneous particle dispersion, while S5 showed elevated particle density and maximum Z-max values (287.8 nm), indicating significant subsurface defects. Overall, the optimal CFP content range of 0.125-0.25 wt% ensures superior mechanical integrity, balanced ductility and acceptable surface quality due to effective stress transfer and uniform dispersion. Higher loading levels, although improving hardness and apparent surface finish, compromise structural reliability due to defect formation and interfacial weakness. Future research should focus on real-time process monitoring, fatigue and durability assessment, hybrid reinforcement strategies and multiscale modeling approaches to further enhance the reliability of SLA-fabricated fiber-reinforced composites for advanced engineering applications in automotive and biomedical sectors.

References