Stiffening of an air beam

Stiffening of an air beam uses an apparatus. The apparatus comprises a high pressure inflatable structure and an inflatable beam structure. The high pressure inflatable structure is inflated causing a first internal pressure. The inflatable beam structure is inflated causes a second internal pressure. The inflatable beam structure is reinforced against bending with the high pressure inflatable structure. The first internal pressure is greater than the second internal pressure.

BACKGROUND OF THE INVENTION

The concept of tensairity involves attaching a thin compressive member along the compressive side of an inflated tube which is loaded in bending. The inflated tube prevents the thin compressive member from buckling, enabling a very high strength and lightweight structure. One of the draw backs of tensairity structures is that a compressive member is included in the structure that can constrain packing and cause a rigid hard point in the structure.

DETAILED DESCRIPTION

Stiffening of an air beam is disclosed. An apparatus comprises a high pressure inflatable structure and an inflatable beam structure. The high pressure inflatable structure is inflated causing a first internal pressure. The inflatable beam structure is inflated causes a second internal pressure. The inflatable beam structure is reinforced against bending with the high pressure inflatable structure. The first internal pressure is greater than the second internal pressure.

Air-air-ity, as we have now termed it, involves replacing a compressive rigid element with a small high pressure tube. This enables many of the benefits of tensairity while still retaining the benefits of a fully inflatable structure. An extreme variant of this is to encase a low pressure volume with a surface layer of high pressure tubes. This can enable the construction of very light weight bodies or structures. Structurally this is closely related to a foam core composite construction, as often is used in aerospace. It is in effect the inflatable variant of foam core construction.

The high pressure surface construction approach can also be applied to inflatable actuator design. It enables high pressure actuation of large low pressure inflatable structures. High pressure actuation can enable the use of small, efficient and lightweight hydraulic systems, that might, for example, use water. This is notable because:it enables tensairity type design using fully inflatable structures.it enables fully integrated tensairity type surface structures.it enables high pressure low volume inflatable actuators on low pressure high volume structures.

The basic principle is to attach a small high pressure tube to the surface of a large low pressure volume so as to constrain it and prevent it from buckling. In this way the full compressive strength of the small high pressure tube can be utilized by the larger lower pressure inflated structure. This is a standard tensairity technique using a small high pressure tube instead of a say small diameter flexible carbon fiber rod.The small high pressure compressive element still allows for inflatable like packing, unlike if using a small diameter carbon fiber rod.Small high pressure tube can utilize high strength composite materials.Air-airity allows for the addition of compressive inflatable structure to the surfaces of large low pressure structures where it is desired.These high pressure tubes can be actuated, enabling the actuation and controlled deformation of large low pressure inflatable structure with a low flow rate high pressure fluid. This can be thought of as a mechanical gearing system.

FIG. 1Ais a diagram illustrating an embodiment of an inflatable beam structure using a high pressure inflatable structure. In the example shown, inflatable beam the high pressure inflatable structure comprises one or more internally pressurized high pressure cells100is reinforced using high pressure inflatable structure104. High pressure inflatable structure104resists bending of inflatable beam structure100due to, for example, force110, force112, and force114. In various embodiments, high pressure inflatable structure104comprises a high strength fiber outer shell with a fluid sealing inner layer. In various embodiments, the high strength fiber comprises polyester, nylon, laminated combinations of polyester and polyethylene fiber such as Cuben™ Fiber, Aromatic polyesters (e.g., Vectran™), Ultra heavy molecular weight polyethylene (e.g., Spectra™, Dyneema®, etc.), Aramids (e.g., Kevlar®, Technora™, Twaron™), thermoset polyurethanes (e.g., Zylon™), polyethylene terephthalate (PET) (e.g., Dacron™, Diolen™, Terylene™, Trevira™ —Polyesters), polyethylene naphthalate (PEN) (e.g., Pentex™), carbon fibers, and/or glass fibers, or any other appropriate fibers. The pressure inside inflatable beam structure100is lower than the pressure inside high pressure inflatable structure104. High pressure inflatable structure104is constrained in its position relative to inflatable beam structure100by a sheath sown onto inflatable beam structure100. In various embodiments, High pressure inflatable structure104is constrained using loops, a plurality of sheaths, adjustable screw threads, a holding cup, or using any other appropriate manner of constraining.

FIG. 1Bis a diagram illustrating embodiments of an inflatable beam using a high pressure inflatable structure and using a tension reinforcement element. In the example shown, inflatable beam structure120is reinforced using high pressure inflatable structure134tension reinforcement element comprising element122, which lies on the front surface of inflatable beam structure120, and element123, which continues on the back surface of inflatable beam structure120. The tension reinforcement element wraps around the internal pressurized beam. Tension reinforcement element, which is comprised of element122and element123, resists bending of inflatable beam structure120(e.g., due to a combination of forces in direction130, in direction132, and in direction128). In various embodiments, tension reinforcement element comprises a high strength fiber or group of fibers, a reinforcement of the material of the internal pressurized beam, the material of the internal pressurized beam, where the material is oriented to have high strength required to tension reinforce the internal pressurized beam (e.g., using a material property, braid, or laminate), or any other appropriate tension reinforcement. In various embodiments, a tension reinforcement element is comprised of high strength fibers (e.g., Aromatic polyesters (Vectran™), Ultra heavy molecular weight polyethylene (Spectra, Dyneema®, etc.), Aramids (Kevlar®, Technora, Twaron), thermoset polyurethanes (Zylon), PET (Dacron, Diolen, Terylene, Trevira—Polyesters), PEN (Pentex), carbon fibers, and/or glass fibers), or any other appropriate fibers. Tension reinforcement element is anchored at position124and position126. Tension reinforcement element is held in its position relative to inflatable beam structure120by being integral or integrated into the material. In various embodiments, tension reinforcement element is constrained using loops, one or more sheaths, is braided or woven into the skin of the internal pressurized beam in production, or using any other appropriate manner of constraining.

In some embodiments, an additional reinforcement element is used. Inflatable beam140is reinforced using tension reinforcement element comprising element144, which lies on the front surface of inflatable beam140, and element142, which continues on the back surface of internal pressurized beam140. Tension reinforcement element, which is comprised of element142and element144, resists bending of inflatable beam140. In some embodiments, two tension reinforcement elements (e.g., such as those illustrated for inflatable beam structure120and inflatable beam140) reinforce a single internal pressurized beam.

FIG. 2is a diagram illustrating embodiments of an inflatable beam cross section. In the examples shown, inflatable beam200has high pressure inflatable structure202. Inflatable beam210has a plurality of high pressure inflatable structures212. Inflatable beam220has high pressure inflatable structures222all around the periphery.

In some embodiments, the inflatable beam structure is a part of one or more of the following: an inflatable structure of a robot, an inflatable structure of a building, an inflatable structure for civil engineering structures, an inflatable structure for automotive systems, an inflatable structure for architectural systems, or an inflatable structure for aerospace systems.

In some embodiments, the inflatable beam comprises one or more internally pressurized cells. In some embodiments, the high pressure inflatable structure comprises one or more internally pressurized high pressure cells.

In various embodiments, the inflatable beam structure is comprised of a material, wherein the material is one or more of the following: polyester, silicon coated materials, nylon, laminated combinations of polyester and polyethylene fiber such as Cuben Fibe™, Vectran™, or any other appropriate material. In various embodiments, the high pressure inflatable structure is comprised of a material, wherein the material is one or more of the following: polyester, silicon coated materials, nylon, Cuben Fiber™, Vectran™, or any other appropriate material.

In some embodiments, a tension reinforcement element wraps around the inflatable beam structure.