Mechanical, thermal, and microstructural analysis of 3D printed short carbon fiber-reinforced nylon composites across diverse infill patterns

This experimental work investigates the effect of infill patterns on mechanical and viscoelastic properties of 3D printed short carbon fiber-reinforced nylon composites (SCFRNCs) made using fused deposition modeling (FDM) technique. Tensile and flexural samples for both quasi-static testing and dynamic mechanical analysis (DMA) were designed using infill patterns of grid, triangular, sinusoidal, honeycomb, and rectilinear geometry. Non-destructive testing (NDT) was conducted using X-ray micro-computed tomography (microCT) to investigate the internal structures of the specimens and to analyze defects and voids. After mechanical testing, fractured specimens were subjected to scanning electron microscopy (SEM) to examine particle size distribution, fiber orientation, and surface morphology. Except infill pattern, all other printing parameters like layer height, printing speed, printing temperature, and infill density were kept fixed due to multi scale analysis. Rectilinear got highest tensile strength of 34.58 MPa. Triangular got highest flexural strength of 23.45 MPa. TGA analysis revealed 7.27% fiber volume fraction in nylon/carbon filament. In both DMA tensile and DMA flexural tests, Triangular exhibited exceptional storage moduli, reaching 747 MPa and 1280 MPa respectively.