Retarding Damages/Cracks via Auxetic effects and Snap-through Instability

Damages/Cracks usually develop in materials under multi-axial loading. When initiated, damages/cracks often evolve rapidly, significantly reducing material load-bearing capability or leading to catastrophic failure. Retarding damages/cracks is the key to improve the mechanical performance of materials. In this investigation, a new concept of retarding damages/cracks via auxetic effects and snap-through instability is proposed. To prove the concept, new multi-phase composites with auxetic effects and snap-through-instability-induced negative stiffness are designed. Finite element models of the new designs are developed. Finite simulations of the new designed materials under both in-plane and out-of-plane loads are conducted.
Different from the prevalent foam-like cellular/porous materials with auxeticity and/or snap-through-instability-induced negative stiffness. The new composites have no pores/voids and are designed to be relatively stiff and therefore can be used as major protective components in resisting indentation/impact loads. In order to further evaluate the mechanical performance of the new designs, numerical simulations are performed to quantify the relationships between structure, material combination and the effective properties of the new designs.