Design and optimization of bioinspired auxetic structure for biomedical applications

Auxetic metastructures are characterized by their unconventional deformation behavior and negative Poisson's ratio (NPR), resulting in lateral expansion under tensile loads rather than normal contraction. They have attracted considerable attention for biomedical applications due to their high energy absorption and biofunctional benefits. Consequently, the present study aims to design and investigate a bioinspired auxetic structure that mimics human organ tissues, such as bone and tendon. The mechanical properties of the scaffolds were experimentally tested using a universal testing machine and verified using the finite element method (FEM) for both conventional auxetic and novel triangle auxetic structures. Furthermore, various gradient triangle auxetic structures are developed and analyzed using FEM to optimize their mechanical and physical properties. The results show that triangle auxetic structures increased Young's modulus and yield strength by 28% and 27.5%, respectively, under compression load and by 35% and 40%, respectively, under tensile load. Moreover, by optimizing the gradient architecture while maintaining a similar porosity, these mechanical properties were further enhanced for both loading conditions.