Three-layered plate exhibiting auxeticity based on stretching and bending modes

In addition to well-known Poisson's ratio under stretching, the concept of Poisson's ratio under pure bending is introduced. There is a large difference between them in the case of 3-layered plate. Effective in-plane Poisson's ratio for symmetrical 3-layered plates are different depending on the loading mode, i.e. the outer layers exert a greater influence under bending mode in comparison to stretching mode. Therefore, nonauxetic-auxetic-nonauxetic cubic plates exhibit an overall auxetic and nonauxetic behaviour under stretching and bending modes, respectively, while the reverse is true for auxetic-nonauxetic-auxetic cubic plates.