Harnessing distinct deformation modes of auxetic patterns for stiffness design of tubular structures

Abstract

Auxetic materials with a negative Poisson's ratio show a unique lateral expansion under tension while their deformation under shear is similar to that of normal materials. Here, we present a novel method to design the stiffness of tubular structures by exploiting these load-dependent distinct deformation modes of auxetic materials. Auxetic cutting patterns are engraved on a tube whose bending and torsional stiffness values are predicted computationally for a comprehensive set of design parameters and measured experimentally for representative designs. Results demonstrate that a wide range of bending and torsional stiffness values can be effectively achieved and controlled independently. The proposed design principle is simple and powerful, and hence can be easily extended to design the mechanical properties of non-tubular structures as well.