Investigation of the equivalent mechanical and thermal properties of the kite-shaped fiber-reinforced cellular structure: Analytical, numerical and experimental approaches

Composite cellular structures are engineered structures that combine different materials to achieve higher strength with lower weight. By mimicking natural structures, such as honeycomb structures, these structures are widely used in the aerospace, automotive, and construction industries owing to their efficiency and versatility. Advances in manufacturing technologies have made it possible to manufacture these structures, allowing for complex designs particular to applications. This paper investigates the development of analytical relationships using energy methods and Castigliano's second theorem to evaluate the equivalent mechanical properties of a double kite-shaped unit cell fabricated from PLA and glass fiber-reinforced PLA. The thermal properties of both unit cells were determined analytically using geometric relationships. A numerical model was employed to compare and validate the mechanical and thermal properties of the double kite-shaped cellular structures. Subsequently, cellular structures with pure PLA and glass fiber-reinforced PLA were fabricated using the Fused Filament Fabrication 3D printing process. The fabricated specimens were then subjected to tensile and compressive tests. A comparison of the experimental and numerical results with those of the analytical model revealed that the proposed analytical model can accurately predict the mechanical properties of the glass fiber-reinforced cellular structures. The mechanical properties of the fiber-reinforced structures were significantly improved. Furthermore, a comparison of the equivalent coefficient of thermal expansion obtained from the numerical and analytical methods for pure PLA and fiber-reinforced specimens showed good agreement. Finally, a comprehensive parametric study was conducted for pure PLA and glass fiber-reinforced PLA cellular structures, and the effect of geometric parameters on the equivalent elastic modulus of the structure was investigated.