Polyhedron cell structure and method of making same
AssigneeUniversity of Iowa Research Foundation
InventorRoderic S. Lakes
Life of this patent
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Abstract
An open cell foam structure that has a negative Poisson's ratio. Structure can be created by triaxially compressing a conventional open-cell foam material and heating the compressed structure beyond the softening point to produce a permanent deformation in the structure of the material. The structure thus produced has cells whose ribs protrude into the cell resulting in unique properties for materials of this type.
Claims7
The method of making a composition of matter having a negative Poisson's ratio comprising the steps of producing a starting material having an open-cell foam structure with each cell being defined by a plurality of ribs;
- applying sufficient force to the starting material in each of three orthogonal directions simultaneously to compress the ribs of the cells inwardly;
- raising the temperature of the material above the softening temperature of the material while maintaining the material in the compressed state;
- cooling the material below the softening temperature while continuing to maintain the material in the compressed state:
- and releasing the applied force once the material has cooled below the softening temperature.
A method of making an open-cell isotropic material having a negative Poisson's ratio comprising the steps of restraining the material from three orthogonal directions during the formation of the material and allowing the material to cool while maintaining the restraint.
An isotropic open-cell material having a negative Poisson's ratio, said material comprising a plurality of interconnected spaced-apart ribs defining a plurality of cells, the ribs in the cells protruding inwardly.
Dependencies are inferred from the claim text.