Mechanical properties of auxetic tubular truss-like structures

The mechanical properties of cellular tubular structures made of centresymmetric cells are evaluated using analytical and numerical simulations. A theoretical model based on bending stiffness of the single ribs composing the unit cell of the tubes is developed, providing estimations for the Poisson's ratios and uniaxial stiffness of the tubular grid-like structures, as well as their Eulerian buckling load. Full 3D Finite Element models in linear elastic regime are used to validate the theoretical results. A continuum nonlinear tube bending model is also presented to show the dependence of the curvature-bending moment versus the Poisson's ratio of the core.