Large deformation of TPU re-entrant auxetic structures designed by TO approach

Auxetic materials are a family of rationally designed artificial structures that have unique effective properties gained from the distribution of the internal architecture rather than of the chemical composition. This article used the modified solid isotropic material with penalization method for topology optimization of 2D re-entrant auxetic structures with different Poisson’s ratios and volume fractions. The obtained structures were verified by the finite-element method (FEM) using the commercial FEM software and also validated by the experimental approach. A good agreement was achieved between the experimental and numerical results. Then, the cell geometry effect on Poisson’s ratio under large tension was investigated. Our study revealed that the location and stiffness of rotation joints are two new parameters affecting Poisson’s ratio value. Poisson’s ratio will decrease by decreasing the stiffness of rotation joints and positioning the rotation joints closer to the middle of the structure. So, from the investigation of the optimizer performance, it was achieved that re-entrant auxetic structures with different Poisson’s ratios could be easily designed by changing just the location of rotation joints. This will be applicable in many applications like sensor field.