Sustainable auxetic honeycomb structures based on sugarcane bagasse fibres and recycled rubber wastes

This work introduces a novel and sustainable approach for recycling sugarcane bagasse fibres and rubber wastes to improve the mechanical properties and the auxetic characteristics of re-entrant honeycomb structures. Tensile tests, analytical predictions, and multiscale computational analysis are conducted to assess the relationship between the mechanical properties and cell geometric variables. A full factorial design (2³) is performed to evaluate the sensitivity of factors such as thickness (2 and 4 mm), length (10 and 20 mm) and angle (−10 and −20°) on the ultimate tensile strength and strain, tensile modulus, and Poisson’s ratio of the auxetic structures. Significant effects and contributions are identified through an Analysis of Variance (ANOVA), indicating that the incorporation of short, random sugarcane bagasse fibres combined with rubber particles enhances the toughness of the auxetic structure. The ultimate tensile strength and tensile modulus have a positive correlation with increased thickness. The Poisson’s ratio is affected not only by individual factors but also by third-order interactions among the re-entrant topologies, with wall length and thickness having the most significant impact on the hybrid re-entrant structure.