RU2549043C1 - Wing box, reinforced with polymer composite material - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to the structure of the wing box of the aircraft. Wing box comprises the outer rigid power massive frame formed by the front and rear longerons and ribs and outer skin, forming the aerodynamic contour and secured on the outer surface of the frame. In this case, the wing box comprises the inner massive power frame, composed from individual grid power units transversely spaced relative to longerons, that fill the space inside the outer frame and fixed on longerons.

EFFECT: weight reduction and improvement of operational reliability of the aircraft wing, increase in hardness, bending and torsion resistance.

11 cl, 9 dwg

Description

The field of technology.

The invention can be used in aviation and space technology and relates to the construction of the caisson, which relates, in particular, to the power elements of the structure, and ensures the safe transmission of power loads that occur on the wing under various flight conditions, while being a fuel tank. The caisson design can also be used in passenger and transport aircraft, in reusable space systems.

The level of technology.

In recent years, there has been a steady tendency towards the transition to the use in the aircraft industry (and, in particular, in the aircraft wing structure) of polymer composite materials based on high-strength artificial fiber.

The main and general disadvantages of the majority of operating and developing aircraft structures using polymer composite materials are the complexity in terms of design and manufacturing technology, which ultimately negates the main advantages that composite materials possess and impedes the widespread use of such constructions. In addition, often there is a need to eliminate the contact of the composite material - carbon fiber from direct interaction with aluminum-magnesium alloys, which leads to the formation of an electrochemical pair, which destroys the metal over time. To eliminate the electrochemical corrosion of metals in the area of contact with carbon fiber, they apply special protective coatings that exclude direct contact of carbon fiber and metal, or use special fasteners, in which, in addition to the main function of connecting and fixing structural elements, the principles of protection against electrochemical corrosion are implemented. These shortcomings are significant limitations for the widespread adoption of structures made of composite materials.

Various technical solutions are known related to the production of wing caissons in which composite materials are used. Among such technical solutions is the structural implementation of the beam used in the formation of parts and components of the power frame of the caisson and formed by two structures adjacent to each other by their vertical walls, and two plates covering the ends of these structures on both sides. Each structure is a structure made up of individual bonded sheathing of composite material. Between the structures, in the zone of their abutment to each other, there is a spatial grid that serves as a means of connecting the beam elements into a single structure and plays the role of an reinforcing element that provides spatial rigidity (see US 2011147045 A1). When using a spatial grid of polymeric material, it is extremely difficult to obtain a part - a beam of significant dimensions. In general, such a beam is a structure that is technologically difficult to manufacture, which significantly increases the cost of the caisson structure when applied.

The closest analogue to the claimed invention is a wing box of the aircraft, containing a rigid power volumetric frame formed by the front and rear spars and ribs separating the inner space of the box into compartments, and an external aerodynamic lining, bonded to the frame. In order to increase the carrying capacity of the wing of the aircraft, it is envisaged to strengthen the volumetric frame with metal tapes or metal beams mounted on the frame and passing both in the longitudinal and transverse directions (see US 4776534 A). The known design is difficult to assemble. In the first case, first, a separate assembly of ribs with ribbons is made by welding and then the assembled nodes are installed at the assembly site of the caisson. In the area of attachment of the tapes to the ribs, it is necessary to provide additional platforms, which complicates the assembly process and leads to an undesirable increase in the mass of the frame. The welding process, especially in hard-to-reach places, is time-consuming. When reinforcing the frame with beams, both fasteners and hinge assemblies are used. In both cases, to attach the beams to the rib, the latter, in the attachment points, needs to be thickened, which leads to an increase in the weight of the caisson, and the assembly process itself is inconvenient, especially in restricted areas. It is also very important that the reinforcement of the caisson frame is provided not over its entire volume, but only at certain linear sections, which does not allow to obtain a sufficiently reliable design in operation.

Disclosure of the invention.

The objective of the invention is to develop the design of the caisson, which would allow to obtain the maximum load-bearing capacity of the wing while ensuring minimum weight and manufacturability.

The technical result achieved by the implementation of the claimed invention is to ensure minimum weight and increase the operational reliability (safe damage to the skin and increased maintainability) of the wing of the aircraft, by eliminating: (a) stringer reinforcement; (b) highly loaded joints, composite-composite and composite-metal in the center section area and in the wing structure; (c) the need to ensure the stability of the composite skin of the wing, since it is intended only for the perception of aerodynamic loads.

To solve this problem, we propose the construction of an aircraft wing box containing a rigid power surround frame formed by front and rear metal spars, metal power ribs designed for hanging wing mechanization elements, also serving as fuel compartment walls, spatial mesh ribs made of composite material with metal frames in the area of attachment to the side members, and the outer skin, forming an aerodynamic contour, which is fixed on the outer surface of the carcass. The additionally used internal volumetric power frame is composed of separate, transversely spaced relative to the side members, volumetric mesh power blocks (ribs) and metal ribs that fill the space inside the outer frame and are mounted on the latter.

Each power unit is formed by a pair of opposing bearing housings located at a distance from one another, and a mesh stretched between them, mounted on the housings.

The load-bearing housing of the power unit has a box-like structure formed by the base and side walls, and facing their open cavities towards each other.

The mesh is formed by an impregnated binder polymer composite material (PCM), stretched between the housings and mounted on the outer surfaces of the side walls of the bearing housings. RMB can be structured in the form of long ones: rovings (tows), threads, ribbons, etc.

The casing is made of a polymer composite material and bonded, from the side of its inner surface, with grids of power blocks.

Power blocks are fixed on the side members of the outer frame with the bases of their bearing bodies.

On the outer surfaces of the side walls of the bearing bodies, nodes are provided for connecting to the mesh structure.

The mesh-forming polymer composite is made on the basis of carbon fiber, or fiberglass, or basalt fiber.

The spars and ribs of the power frame and the bearing bodies of the power blocks are made of metal alloys.

The wing skin is made of a polymer composite material based on carbon fiber, fiberglass, basalt fiber.

A brief description of the drawings.

The invention is illustrated by drawings, where:

in FIG. 1 shows a General view of the wing box, complete;

in FIG. 2 - general view of the wing box, an exploded view;

in FIG. 3 - power mesh block in a perspective view;

in FIG. 4 - shows a schematic diagram of the design of the wing box;

in FIG. 5 - power mesh block, top view;

in FIG. 6 - power mesh block, side view;

in FIG. 7 - the same, end view;

in FIG. 8 is a fragment of a mesh power unit, a top view of a node with hooks;

in FIG. 9 is a section along AA in FIG. 8.

The implementation of the invention

The proposed design of the wing box shown in FIG. 1, consists of spars 1 and 2, ribs 3 forming an external rigid power volumetric frame, and external aerodynamic casing 4. Spars and ribs are made of titanium, or of duralumin, or of metal composites. The casing 4 is made of a polymer composite material, for example carbon fiber (preferably), or fiberglass, or basalt plastic.

Inside the external power frame there is an internal volumetric power frame 5, composed of separate power mesh blocks 6. Blocks 6 are located transversely relative to the side members 1, 2 and fill the space inside the power frame, adjoining close to each other. Each power unit 6 extends from the vertical strut of one spar to the vertical strut of another spar.

The power unit 6 includes a pair of opposite forming metal bearing bodies 7 and 8 located at a distance from one another. Each housing 7, 8 has a box-like structure formed by the base 9 and the side walls 10, 11, 12, 13.

The cases 7, 8 of each power unit 6 are interconnected by a grid (mesh structure) 14, which together with the bodies forms a single rigid structure. Cases 7, 8 in the power unit 6 are facing each other with their open cavities. Blocks 6 with bases 9 are fixed by mechanical or adhesive-mechanical fasteners on the side members 1, 2. On the side walls 10, 11, 12, 13 of the buildings 7, 8 there are nodes 18 that provide a connection to the mesh structure. These nodes include the head-hooks 15, which are loop-shaped covered by mesh elements. To prevent the mesh from slipping from the hooks 15, stops 16 are provided that block the mesh loop in the hook.

The mesh 14 in each block is made of a polymer composite material impregnated with a polymer binder, structured in the form of a roving (tow), thread, tape, etc. Each of the four side faces of block 6 is formed by the corresponding pairs of side walls (10-10, 11-11, 12-12, 13-13) of the buildings 7, 8 and a mesh structure made of a polymer composite material, for example, a long roving stretched between the pairs of side walls buildings. The polymer composite material of the mesh is made on the basis of carbon fiber, or fiberglass, or basalt fiber. As a result, the monolithic mesh power frame is docked to the side metal box blocks using special hooks. One of the preferred meshing options is shown in FIG. 3, 5, 6. Formation begins by pulling between the hulls 7, 8 of the supporting segments 17 of the roving, which are tensioned and fixed in nodes 18. The supporting segments 17 are formed by several streams on each of the four surfaces of the block 6, forming an intermediate frame. After tensioning and fixing on the housings 7, 8 of the support segments 17, a long roving is wound in a spiral (position 19) in the forward and reverse directions, while rounding the heads of the hooks 15. During the winding, the long roving rests on the previously stretched and under tension segments 17 , which eliminates the sagging volumetric mesh structure.

The sheathing 4 is bonded with its inner surface to the adjacent mesh 14.

The skin forms the outer contour of the wing and receives aerodynamic pressure, which is transmitted through the grid 14 to the side members 1, 2 and metal ribs 3 of the outer wing frame. The grid 14 together with the side casings 7, 8 forms a spatial element of the internal power frame and provides the necessary torsional stiffness of the wing.

The tightness of the structure is ensured by the outer skin 4, glued to the side members 1, 2, ribs 3 and mesh blocks 6. The perception of aerodynamic loads is also provided by the outer skin 4, glued to the side members 1, 2 and ribs 3 and internally reinforced by volumetric mesh blocks 6.

It is very important that the composite mesh of the volumetric mesh blocks 6 located inside the outer volumetric frame formed by the side members 1, 2 and ribs 3 is glued with the outer skin 4 around the entire contour, thus forming a single rigid structure that allows reliable fuel storage during different flight conditions.

In addition, to achieve a long resource, the following principles apply that distinguish the proposed design.

- The grids of blocks 6 are connected to the housings 7, 8, preferably made of titanium, and the housings 7, 8 are inserted into the structure from the side members 1, 2 and ribs 3, forming a circuit (grid + titanium = elimination of electrochemical corrosion) + titanium. That is, the connection of the reinforcing mesh with the cases 7, 8 of titanium eliminates the occurrence of electrochemical corrosion between the carbon fiber and light alloys and provides further contact only titanium + titanium or titanium + metal composites.

- The use of a system of milled connection elements (hooks 15, 16) to which a reinforcing mesh of polymer composite material is attached. This allows you to ensure maximum structural strength of the joints, and, accordingly, to ensure the strength of the connection pair consisting of a hook and mesh.

The assembly of the wing box is as follows.

Power blocks 6 are assembled at separate assembly sites. For each block 6, first, two box-shaped cases 7, 8 are formed, either by milling from a solid billet, or by collecting each of them from the base 9 and located along its perimeter and perpendicular to its side walls 10, 11 , 12, 13. At the same time, hooks 15, 16 are preliminarily milled onto the upper surfaces of the side walls 10, 11, 12, 13, after which all the walls are welded to the base 9 and welded together on adjacent sides to obtain a box-like structure. Each pair of obtained box-shaped housings 7, 8 is placed in special technological equipment, spacing them from each other by a distance determined by the parameters of the power volume unit 6, and orienting them with the open cavities of the boxes to each other. A reinforcing polymer composite material (roving) impregnated with a polymer, for example epoxy, binder is pulled between the bodies 7, 8. The roving is carried out from one block body to another, while enveloping the hooks 15, milled on the outer surfaces of the side walls 10, 11, 12, 13, gradually forming the upper, lower and side mesh surfaces of the block 6. The ends of the roving are fixed on the hooks 15. Using rigs part the hulls 7, 8 in opposite directions, thereby providing the necessary tension of the rovings between the hulls. The formed block together with the equipment is placed in a thermal furnace, heated to a predetermined temperature and provide the necessary exposure. The polymer binder cures with which the rovings are impregnated, while in the places of contact with the hooks, the rovings are caught with the hooks. The blocks 6 extracted from the thermal furnace are cooled. In FIG. 3, 5, 6, the mesh structure of block 6 is shown in the form that it has at the outlet of the thermal furnace. Ready-made blocks 6 fill the entire space of the external power frame, installing the blocks close to each other and close to the metal ribs, and fasten them to the spars 1, 2 with mechanical or adhesive-mechanical fasteners. Apply an even layer of glue to the inner surfaces of the lining and glue the lining to the surfaces of the side members 1, 2 and to the nets of the rovings. The area of the mesh should ensure the strength of its bonding with skins and withstand aerodynamic loads.

Due to the fact that the present invention takes into account the main disadvantages of the wing caisson designs currently used, the proposed design has the following principal advantages, namely:

- panels reinforced by stringers are excluded from the wing structure;

- the use of a block structure, assembled together, allows to increase rigidity, resistance to bending and torsion with a minimum mass of the structure, to ensure high tightness characteristics in the most severe operating conditions;

- application of the principle of composite reinforcing mesh plus titanium eliminates the formation of electrochemical corrosion between carbon fiber and light alloys and ensures contact between titanium + titanium or titanium + metal composite;

- the use of milled hooks to fix the elements of the composite mesh allows you to increase the strength, rigidity and life of the structure.

The proposed wing box can be used as one of the main power elements of the wing in aviation, in reusable space systems.

To create the proposed wing box, able to work in the most severe conditions for the longest time and at the lowest possible operating costs, there are all the necessary materials and production technologies.

Claims (11)

1. A wing box of an aircraft, comprising an external rigid power volumetric frame formed by front and rear spars and ribs, and an outer skin forming an aerodynamic contour and mounted on the outer surface of the frame, characterized in that it has an internal volumetric power frame selected from separate transversely located relative to the side members, mesh power units filling the space inside the outer frame and mounted on the side members. 2. Caisson according to claim 1, characterized in that each power unit is formed by a pair of opposing load-bearing housings located at a distance from one another, and a mesh stretched between them, mounted on the housings. 3. The caisson according to claim 2, characterized in that the load-bearing housing of the power unit is box-shaped, formed by a base and side walls, and facing their open cavities towards each other, and the grid is formed by an impregnated binder polymer composite material, stretched between the cases and mounted on the outer surfaces of the side walls of the bearing bodies. 4. The caisson according to claim 2, characterized in that the casing is made of a polymer composite material and bonded from the side of its inner surface with grids of power blocks. 5. Caisson according to claim 3, characterized in that the power units are fixed to the side members with the bases of their bearing bodies. 6. Caisson according to claim 3, characterized in that on the outer surfaces of the side walls of the bearing bodies, nodes are provided that provide connection to the grid. 7. Caisson according to claim 3, characterized in that the polymer composite material is made on the basis of carbon fiber, fiberglass, basalt fiber. 8. Caisson according to claim 1, characterized in that the spars and ribs are made of duralumin, or of titanium, or of a metal composite. 9. Caisson according to claim 2, characterized in that the load-bearing housing of the power units are made of duralumin, or of titanium, or of a metal composite. 10. Caisson according to claim 4, characterized in that the casing is made of a composite material based on carbon fiber, fiberglass, basalt fiber. 11. Caisson according to claim 3, characterized in that the meshing polymer composite material is based on carbon fiber, or glass fiber, or basalt fiber.

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