Mechanical Property Characterization of 3D-Printed Carbon Fiber Honeycomb Core Composite Sandwich Structures

The present study evaluated the mechanical properties of 3D-printed carbon fiber honeycomb core composite sandwich structures. Mechanical tests, such as tensile, flexural, edgewise, and flatwise compression following the ASTM standards, were performed. A total of 12 samples (three samples in each test category) were fabricated by keeping the core face parallel to the face sheet using a Markforged FDM 3D printer, considering geometric dimensions, such as a face sheet thickness of 3.2 mm, a core cell size of 12.7 mm, and a cell wall thickness of 4.5 mm. Force-displacement data were recorded from all the tests performed and converted into a stress-strain plot with energy absorption characteristics. The average tensile strength of 33.45 MPa and Young's modulus of 495.42 MPa from the tensile test, the flexural strength of 44.21 MPa and the flexural modulus of 391.32 MPa from the flexural test, and the energy absorption of 132.29 and 147.05 J, respectively, during edgewise and flatwise compression were estimated. High-energy absorption under flatwise compression due to the dominant core crushing behavior of the honeycomb core was observed. However, a more dominant bending behavior of the sandwich was observed in cases of edgewise compression. No delamination and debonding of the face sheets was observed under either edgewise or flatwise compression. Based on these results, the 3D-printed composite honeycomb sandwich structure studied here can be considered for its high-energy impact resistance and lightweight design applications.