Design and mechanical performance of stretchable sandwich metamaterials with auxetic panel and lattice core

Sandwich structures are widely used in engineering as lightweight and high-strength materials. In recent years, there has been increasing attention toward new design ideas aimed at improving the adaptability and variability of sandwich structures for broader applications. This paper proposes a new stretchable sandwich structure. Experiments and finite element methods are conducted to provide the influence of stretchable design on the mechanical properties of traditional sandwich structures. Then, three novel stretchable sandwich structures with 3D lattice core layers are also designed to explore the applicability of this method. The results demonstrate that the stress and energy absorption capacity of stretchable lattice sandwich structures remains essentially constant. In addition, stretchable sandwich structures possess the capability of in-plane deformation and active bending. By combining the functional characteristics of sandwich structures and rotating polygons, stretchable sandwich structures can adjust their surface area, porosity, and in-plane negative Poisson's ratio effect while maintaining bearing capacity. This study suggests improvements in the utilization and adaptive capacity of sandwich structures in defense engineering and other applications by overcoming the problem of limited deformation faced by traditional sandwich structures.