Bimaterial honeycomb structures additively manufactured with short carbon fiber composites: Design proposition, asymptotic homogenization and properties testing

Additive manufacturing allows the production of multiphase structures with customizable mechanical properties. This study proposes a unit cell for bimaterial honeycombs, followed by experimental and numerical tests. The honeycombs were fabricated by FFF (fused filament fabrication) material extrusion using PET and PET-CF (PET with short carbon fibers), with tool paths generated directly in FullControl design software. Each beam of the unit cell contains both materials side-by-side (double-wall configuration). The composite content is adjustable by varying the thicknesses of the phases, allowing modulation of equivalent properties. Compression tests evaluated the mechanical behavior, while Asymptotic Homogenization (AH) was used to numerically estimate the equivalent properties. Response surfaces based on AH were developed to estimate variations in equivalent properties as a function of composite content. The experimental and numerical results showed strong agreement. The main contribution of this work is the proposal of honeycombs with tailorable mechanical properties, supported by numerical simulations and experiments. The proposed honeycombs have the potential to modulate mechanical properties, as demonstrated through the design of composite material phases: certain configurations exhibit increased structural performance while maintaining a similar use of expensive reinforcing material in terms of volume fraction. These findings highlight the potential for functionally tailored structures in lightweight engineering applications.