Abstract: NPR (negative Poisson's ratio) components for vehicle and other applications generally assume a tubular structure defining an axis, a length and a cross section. The structure is composed of a plurality of nested, double-V unit cells, each unit cell comprising a pair of side points A and B defining a width, a first pair of tensile members interconnecting points A and B and intersecting at a point C forming a first V shape, a second pair of stuffer members interconnecting points A and B and intersecting at a point D forming a second V shape. The unit cells are connected in a first direction with the point B of one cell being connected to point A of an adjoining cell, and so on, until completing a continuous band. The unit cells are further connected in a second direction with the point D of one cell being connected to point C of an adjoining cell. In one embodiment, the bands are stacked radially outwardly from the axis to form a bushing.

Abstract: Reconfigurable, expandable-collapsible structures based upon negative Poisson's ratio (NPR) auxetic unit cells achieve rapidly deployable apparatus, devices and systems. A plurality of joint bodies, each joint body having a plurality of connection features, are coupled to interconnecting link members with opposing ends, each end including connection features that engage with the connection features of the joint bodies. The link members pivot about different axes relative to the joint bodies, thereby forming an expandable and collapsible structure having a height and a width. The link members form an array of geometric unit cells when the structure is expanded, and the height and the width of the structure when expanded are both greater than the height and the width of the structure when collapsed. In certain embodiments the structures have unit cells based upon triangles or bowtie shapes.

Abstract: Negative Poisson's ratio (NPR) or auxetic are used to make lightweight wheels and runflat tires. The NPR tires can be tailored and functionally-designed to optimally meet the runflat requirements for both military and commercial vehicles. NPR-runflat tires may be fabricated using standard materials and simple manufacturing processes, resulting in low-cost and high-volume production. In preferred embodiments the runflat tire designs are fully compatible with Central Tire Inflation Systems (CTIS), while providing a performance equivalent to current military vehicle solutions but at half the weight. An auxetic wheel according to the invention comprises a line defining an axis of rotation; and a plurality of concentric rings of unit cells surrounding the axis, each unit cell being constructed of a plurality of members defining a Negative Poisson's Ratio (NPR) structure.

Abstract: Negative Poisson's ratio (NPR) or auxetic structures, including three-dimensional auxetic structures, are disclosed and applied to various applications. One such structure comprises a pyramid-shaped unit cell having four base points A, B, C, and D defining the corners of a square lying in a horizontal plane. Four stuffers of equal length or different lengths extend from a respective one of the base points to a point E spaced apart from the plane. Four tendons of equal length or different lengths, but less than that of the stuffers, extend from a respective one of the base points to a point F between point E and the plane. In three-dimensional configurations, a plurality of unit cells are arranged as tiles in the same horizontal plane with the base points of each cell connected to the base points of adjoining cells, thereby forming a horizontal layer.

Abstract: Improved composite armor designs uses optimally shaped ceramic pellets, a specific stacking geometry and a web system for patterning the pellets, improving manufacturability, and providing additional structural reinforcement. Lightweight, composite ballistic armor according to the invention may comprise an array of ceramic pellets, each pellet having a front surface, a back surface and a longitudinal centerline, and wherein the front surface of each pellet is intentionally convex. The front surface of each pellet may be hemispherical, in which case the cross-section of the pellet taken perpendicular to the centerline may be oval-shaped. Alternatively, the front surface of each pellet may be elliptical, in which case the cross-section of the pellet taken perpendicular to the centerline may be circular. In the preferred embodiment, the back surface of each pellet is formed at the same angle relative to its centerline, with the pellets being arranged with the flat surfaces lying in a plane.

Abstract: Biomimetic tendon-reinforced” (BTR) composite structures feature improved properties including a very high strength-to-weight ratio. The basic structure includes plurality of parallel, spaced-apart stuffer members, each with an upper end and a lower end, and a plurality of fiber elements, each having one point connected to the upper end of a stuffer member and another point connected to the lower end of a stuffer member such that the elements form criss-crossing joints between the stuffer members. The stuffer members and fiber elements may optionally be embedded in a matrix material such as an epoxy resin. The fiber elements are preferably carbon fibers, though other materials, including natural or synthetic fibers or metal wires may be used. The stuffer members may be rods, tubes, or spheres, and may be constructed of metal, ceramic or plastic. The stuffer members are preferably spaced apart at equal distances. If the members are tubes, the fiber elements may be dressed through the tubes.

Abstract: Improved composite armor designs use optimally shaped ceramic pellets and a web system for patterning the pellets, improving manufacturability, and providing additional structural reinforcement. The result is lightweight, composite hybrid structures for ballistic protection particularly suited to tactical ground vehicles. The preferred embodiment is a combination of three major components: 1) an optimally designed web system that allows armor tiles to be attached to it and that can be easily integrated with existing vehicle structures; 2) an advanced composite armor unit using a patent-pending BTR (Bio-mimetic Tendon-Reinforced) material as the supporting structure; and 3) optimally placed “waiting materials” which can provide enhanced ballistic impact resistance, energy absorption capability and structural integrity. These “waiting materials” are structural members that are not active at the beginning of the ballistic impact, but become active when needed or the active members have failed.