Axisymmetric auxetics

Auxetic materials expand/contract transversely while tensioned/compressed in the longitudinal direction, thus they possess a negative Poisson's ratio. According to the theory of elasticity, their existence in isotropic forms is theoretically possible, however, they are found in nature only in anisotropic forms. Auxetics are expected to possess enhanced relative static and dynamic properties, thus, several auxetic composites have been proposed and manufactured to mimic such behavior. This study shows the development of axisymmetric auxetics, a novel class of negative Poisson's ratio composites obtained by the revolution of reentrant lattices in turn of an axis. It is shown by experimental testing and FEA that an auxetic circumferential deformation mechanism increases the overall Poisson's ratio and promotes an elevation of the Specific Young's modulus relative to regular honeycombs. Furthermore, the developed composites are compared in terms of Specific Young's modulus and densities to commercial foams and other non-stochastic auxetics. It is concluded that they present enhanced specific properties for relative densities in the range of 0.28-0.35 and may be a promising route for future applications.