Mechanical and dynamic performance of 3D-printed continuous carbon fibre Onyx composites

The increasing attention towards 3D-printed fibre-reinforced thermoplastic composite structures is due to their superior characteristics, ability to produce intricate architectures, repeatability, and short lead times. This experimental study aims to investigate the mechanical and dynamic behaviours of 3D-printed composite structures under tensile and impact tests. Different types of samples are designed, including Onyx layers, triangular infill patterns (30 % and 40 % infill density), and continuous carbon fibre layers (two, four, six, and eight layers). Scanning electron microscopy (SEM) and X-ray micro-computed tomography (mu CT) analyses are conducted to visualise the morphological characterisation and observe the delamination and damage of the composite structures. The results of the study reveal that the inclusion of carbon fibre reinforcement layers increases the stiffness and tensile strength of the composite structures. Furthermore, the addition of fibre layers in the composite panels provides critical support in damage resistance against impact loading. In contrast, sandwich structures without reinforcement layers are fatally punctured by the impact force, resulting in significant damage on both the impacted and bottom surfaces. The composite sandwich panels with fewer fibre-reinforced layers and lower infill density become softer and absorb impact energy better.