Macroscopic auxetic behaviour, i.e., a negative Poisson's ratio, means, just the other way as usual, that axial tension and axial pressure makes a bar thicker and slimmer, respectively.
In this project, such a material behaviour shall be represented by non-convex micro-mechanical beam models where the dynamic behaviour of such a unit cell on the micro-mechanic level shall be described by applying the boundary element method for Timoshenko beams. Then, with classical and non-classical homogenization techniques, e.g., neural networks or genetic algorithms, the macroscopic auxetic behaviour of the unit cell is determined. Since also dynamic effects on the micro-mechanical level are taken into account, the macroscopic behaviour can be time-dependent, i.e., viscoelastic, although at the micro-mechanical only elastic behaviour is given. With this methodology either sandwich structures with negative Poisson's ratio in one direction or materials with different damping behaviour in different directions can be modelled.