Abstract: A method of manufacturing a foam having a Poisson's ratio which varies across at least a region of the foam in a gradient distribution involves the steps of: a) providing a housing defining an internal space having an inlet aperture and an outlet aperture; b) providing an open-cell foam of a size and shape configured to fit inside the internal space of the housing; c) positioning the foam inside the internal space of the housing; d) establishing a flow of air through the foam via the inlet and outlet apertures; e) heating the foam to a predetermined temperature while maintaining the flow of air through the foam; and f) subsequently cooling the foam while continuing to maintain the flow of air through the foam. A foam of such a type is also presented.

Abstract: A vibration damping insert configured to seat within a cell of a cellular structure and to span the cell cavity. The insert comprises a first portion formed of a first material and a second portion formed of a second material having lower stiffness than the first material. The first portion is arranged to constrain deformation of the second portion to be in a predetermined direction. The invention also comprises a vibration damping body comprising a cellular structure formed of a plurality of tessellating cells and a vibration damping insert as described. The vibration damping insert is mounted in at least one of the cells in the cellular structure. The invention also comprises a method of manufacturing a vibration damping body.

Abstract: A vibration damping body including an auxetic cellular structure having cell walls therein formed substantially of a first material having a first stiffness, the cellular structure further including a second material attached to said cell walls, the second material being selectively located throughout the cellular structure so as to include less than 50% by mass thereof and having a second stiffness which is lower than said first stiffness.

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.

Abstract: A method of manufacturing a foam having a Poisson's ratio which varies across at least a region of the foam in a gradient distribution involves the steps of: a) providing a housing defining an internal space having an inlet aperture and an outlet aperture; b) providing an open-cell foam of a size and shape configured to fit inside the internal space of the housing; c) positioning the foam inside the internal space of the housing; d) establishing a flow of air through the foam via the inlet and outlet apertures; e) heating the foam to a predetermined temperature whilst maintaining the flow of air through the foam; and f) subsequently cooling the foam whilst continuing to maintain the flow of air through the foam. A foam of such a type is also presented.

Abstract: A vibration damping insert configured to seat within a cell of a cellular structure and to span the cell cavity. The insert comprises a first portion formed of a first material and a second portion formed of a second material having lower stiffness than the first material. The first portion is arranged to constrain deformation of the second portion to be in a predetermined direction. The invention also comprises a vibration damping body comprising a cellular structure formed of a plurality of tessellating cells and a vibration damping insert as described. The vibration damping insert is mounted in at least one of the cells in the cellular structure. The invention also comprises a method of manufacturing a vibration damping body.

Abstract: A vibration damping body including an auxetic cellular structure having cell walls therein formed substantially of a first material having a first stiffness, the cellular structure further including a second material attached to said cell walls, the second material being selectively located throughout the cellular structure so as to include less than 50% by mass thereof and having a second stiffness which is lower than said first stiffness.

Abstract: A method of manufacturing a foam having a negative Poisson's ratio comprising the steps: placing a pad 12 of open cell polyurethane foam on a moulding surface 4; placing a flexible membrane 18 over the exposed surface of the foam to create a sealed chamber 20 between the moulding surface 4 and the flexible membrane 18 in which the foam pad 12 is disposed; applying an isostatic pressure difference between the inside and the outside of the chamber 20 thereby collapsing the foam pad 12 between the flexible membrane 18 and the moulding surface 4; heating the foam pad 12 to a predetermined temperature, and subsequently cooling the foam pad 12 while collapsed.

Abstract: A method of manufacturing a foam having a negative Poisson's ratio comprising the steps: placing a pad 12 of open cell polyurethane foam on a moulding surface 4; placing a flexible membrane 18 over the exposed surface of the foam to create a sealed chamber 20 between the moulding surface 4 and the flexible membrane 18 in which the foam pad 12 is disposed; applying an isostatic pressure difference between the inside and the outside of the chamber 20 thereby collapsing the foam pad 12 between the flexible membrane 18 and the moulding surface 4; heating the foam pad 12 to a predetermined temperature, and subsequently cooling the foam pad 12 while collapsed.