Method of manufacturing a foam showing a gradient poisson's ratio behaviour

Abstract

A method of manufacturing a foam having Poisson's ratio which varies across a region of the foam in a gradient distribution from a negative value to a positive value includes the steps of: a) providing an open-cell foam; b) applying a compressive force to a localised region of the foam to collapse the foam in the localised region, whilst leaving other regions of the foam un-collapsed; c) heating the foam to a predetermined temperature whilst continuing to apply the compressive force; and d) subsequently cooling the foam whilst continuing to apply the compressive force. A foam having a first region which exhibits a negative Poisson's ratio, a second region which exhibits a positive Poisson's ratio, and an intermediate region located between the first and second regions and across which the Poisson's ratio of the foam varies in a gradient distribution from a negative value to a positive value.

Dependencies are inferred from the claim text.