Design of Novel Auxetic Hybrid Metamaterials: Experimental and Numerical Study

Cellular structures have numerous unique advantages, including a high strength-to-weight ratio, exceptional energy absorption, and minimal material necessity. They are made up of a network of struts or tiny unit cells that are connected to one another. Recent years have seen the emergence of multifunctional auxetic mechanical metamaterials, endowed with novel mechanical properties and multi-functionalities, offering an extraordinary opportunity to disrupt designs in several sectors. Auxetic structures also have significant disadvantages, such as their generally low stiffness and stability. Filling auxetic two-phase composites with soft materials is a typical practice to enhance their mechanical performance. In the present work, the hybridization of two different auxetic structure types as a potential method to enhance the mechanical properties of auxetic metamaterials is presented. In this study, one reentrant honeycomb lattice (as control) and six hybrid metamaterials were created using chiral and re-entrant auxetic unit cells together. Experimental investigation and finite element simulation are conducted to assess the mechanical properties and deformation features of these hybrid metamaterials. The correlation between numerical and experimental data was significant. The hybrid structures had greatly improved stiffness and compressive strength without losing auxeticity in comparison to the re-entrant honeycomb lattice.