Experimental and Numerical Investigation of Additively Manufactured Continuous Fibre-Reinforced Composites for UAV Structures

Additive manufacturing of continuous fibre-reinforced composites enables lightweight and structurally efficient solutions for aerospace applications. In this work, specimens were fabricated with an Anisoprint Composer A3® printer using carbon fibres and a polyamide (PA) matrix. Unidirectional samples were mechanically tested to determine the Young’s modulus and establish the baseline stiffness of the printed system. Tensile test revealed a Young’s modulus of 37.84 GPa, and three-point bending testing indicated a bending modulus of 26.4 GPa. To improve quality, printing parameters were varied to reduce void formation, and computed tomography (CT) scans were used to quantify porosity. Lowest obtained specimen porosity volume content was 10.06%. To extend the experimental investigation, a numerical representative volume element (RVE) model with three constituents, matrix, fibres, and voids, was developed based on the CT images. This approach provides realistic microstructural representation and offers predictive capability for effective material properties, particularly in assessing the role of voids on stiffness. At the structural level, several wing rib geometries representative of small fixed-wing UAVs were printed and tested. Crushing forces were normalized by weight to evaluate load-bearing efficiency. Results indicate that analysed rib designs combined with reduced porosity improve strength-to-weight performance. The integration of mechanical testing, CT-based analysis, and RVE modelling demonstrates a comprehensive pathway to optimize fibre-reinforced composites in UAV design.