Tunable mechanical response of elastic media : from negative Poisson ratio to negative compressibility
Corentin Coulais (Leiden University), Martin van Hecke (Leiden University), Bastiaan Florijn (Leiden University)
Soft Materials and Structures
Mon 10:45 - 12:15
Barus-Holley 158
We probe the mechanical response of 2d and 3d elastic media, structured by a crystalline pattern of holes of two different sizes. While compressed under uni-axial loading, the holes pattern transforms, the overall material undergoes an exautic mechanical response. Hole size and aspect ratio play a crucial role on this mechanical response, and eventually lead to a negative stiffness. Further bi-axial loading leads to a wealth of new phenomena, including mechanically switchable hysteresis and memory effects. We further propose a simple model of coupled beams, and describe the various buckling instabilities that can occur. This allows us to recover the main features of the experimental behavior.