Thermal and morphological analysis of various 3D printed composite honeycomb cores

Fused deposition modeling (FDM) was employed to manufacture honeycomb core structures using polylactic acid (PLA) and short carbon fiber (CF) filled PLA composite filaments. For honeycomb structures, circular, square and hexagonal cores were manufactured to explore geometric effects on 3D printing quality. Various physical, thermal and compressive properties for their morphological features were holistically investigated. A comprehensive void analysis was also presented using optical microscopy, scanning electron microscopy (SEM) and X-ray computed tomography (XCT). Thermal analysis using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) was also performed on honeycomb cores. It was manifested that material porosity was dependent on the structure, and had an inverse relationship with compressive properties. Hexagonal core structures especially possessed the lowest amount of material porosity with highest compressive strength relative to circular and square cores. It was also shown that XCT could be employed to estimate the microporosity within the structure, and further could be a useful tool to study the effect of filler addition in the matrix. In this study it was revealed via XCT that PLA/CF composite honeycomb cores yielded lower compressive properties compared to neat PLA structures owing to a large amount of microporosity generated in 3D printing process.