Effect of fiber reinforcement orientation on the interlaminar fracture toughness in mode I, mode II, and mixed-mode I/II fracture of onyx/aramid 3D printed composites Academic Article in Scopus uri icon

abstract

  • The fracture behavior of 3D printed composite materials (3DPCM) remains underexplored, particularly for Onyx-based composites reinforced with continuous Aramid fibers. This study evaluates the interlaminar fracture toughness of Onyx/Aramid composites under Mode I, Mode II, and Mixed-mode I/II loading using Double Cantilever Beam (DCB), End Notch Flexure (ENF), and Mixed-Mode Bending (MMB) methods. Crack initiation and propagation were analyzed for two aramid fiber orientations: 0° and 90°. The results indicate that aramid fiber orientation significantly influences crack growth. Under Mode I, DCB0° and DCB90° samples exhibited similar crack initiation toughness, 1.06kJ/m2 and 1.62kJ/m2, respectively. However, crack propagation was more unstable in 90° samples. In Mode II, ENF0° samples exhibited higher fracture toughness 5.36kJ/m2 than ENF90° 3.72kJ/m2, demonstrating the effect of reinforcement alignment. Mixed-Mode tests require less energy for crack initiation, 0.98kJ/m2 for MMB0° and 1.32kJ/m2 for MMB90°, than Mode I or II, emphasizing the sensitivity of 3DPCM materials to combined tensile-shear loads found in real-world applications. SEM analysis revealed additive manufacturing defects such as voids, fiber breakage, and poor interfacial adhesion, attributed to low pressure during fabrication. These defects lower fracture toughness and contribute to premature failure. This research provides valuable data to the limited literature on Onyx/Aramid 3DPCM and emphasizes the influence of fiber orientation, fracture mode, and processing quality. Further research should focus on optimizing the mixed-mode testing and post-processing techniques that can improve the performance and reliability of final products made by 3DPCM. © 2025 Elsevier Ltd

publication date

  • January 1, 2026