Fatigue and Static Damage Behavior of Hybrid Re-Entrant Active Link-Based Auxetic

Metamaterials have become an attractive avenue for structurally demanding mechanical and aerospace systems. Specifically, auxetic metamaterials are highly valued for their enhanced mechanical properties at low relative densities, such as their Poisson’s ratio, ductility, and shear modulus. Literature has demonstrated limited progress in understanding the fatigue response of 2D auxetics; there is inadequate insight into stretch-bending-dominant auxetic topologies. These novel topologies offer a higher stiffness-to-weight ratio and improved ductility compared with conventional stretch or dominant structures. Such material characteristics are particularly desirable for applications requiring tough but lightweight properties. To augment energy absorption through enhanced bending capabilities, the authors integrated active links into hybridized re-entrant double-arrowhead structures. A synergistic combination of stretch and bending mechanisms is engineered to achieve the desired structural properties. This research examined the fatigue and static damage behavior of a new auxetic design incorporating active links. A finite element numerical approach is employed to analyze auxeticity, ductility, fatigue, and static damage behavior for comprehensive characterization of mechanics and fatigue. Results demonstrated the active link topology to have increased the normalized flexural capacity by 300%. Overall, the new topology demonstrated improved fatigue behavior over the base topology.