Self-adaptive skin structure suitable for cross-airspace speed domain morphing aircraft

Abstract

The invention relates to a self-adaptive skin structure suitable for a cross-airspace speed domain morphing aircraft, and belongs to the technical field of intelligent skin. The skin structure is of a multi-layer form and sequentially comprises a heat insulation protection layer, a flexible skin base body, a sensing layer and a bearing and driving layer from the outer side to the inner side. Wherein the outermost side adopts a fiber sandwich structure formed by coating aerogel with an alumina fiber reinforced alumina composite material as a heat insulation protective layer; a high-temperature-resistant carbon fiber elastic matrix composite material is used as a flexible skin matrix; a bearing layer and a driving layer on the inner side are integrally designed, and a honeycomb cell element structure driven by an integrated high-temperature shape memory alloy wire is adopted; an optical fiber sensor is embedded between the flexible skin substrate and the bearing and driving layer, the optical fiber sensor realizes direct strain measurement, and the thickness change of the skin is calculated through a strain measurement value; the method can realize self-adaptive active flexible deformation of the skin when the cross-airspace speed domain aircraft is in a hypersonic flight stage, and has important application value in the field of skin design of the cross-airspace speed domain aircraft.

Description

Technical Field

[0001] The present invention relates to an adaptive skin structure suitable for a cross-space speed domain variant aircraft, which adopts a multi-layer form, and is composed of a heat insulation protection layer, a flexible skin matrix, a sensor layer, and a load-bearing and driving layer from the outside to the inside. A high-temperature resistant carbon fiber elastic matrix composite material is used as the flexible skin matrix, and a sandwich structure of alumina fiber reinforced alumina composite material coated with aerogel fiber is used as the thermal insulation protection layer on the outside. The load-bearing and driving structure on the inside adopts a honeycomb cell structure driven by an integrated high-temperature shape memory alloy wire, and an optical fiber sensor is embedded between the flexible skin matrix and the load-bearing and driving layer. The skin structure can realize high-temperature protection in the hypersonic flight stage, and can also realize adaptive active deformation and have self-sensing capabilities. The present invention is suitable for the adaptive skin of cross-space speed domain variant aircraft, and belongs to the field of intelligent skin technology. Background Art

[0002] In the face of the development requirements of fast-penetrating military aircraft and low-cost intelligent spacecraft, the development of hypersonic aircraft has become an important national scientific and technological strategy. Adaptive cross-airspace / speed domain aircraft can achieve better efficiency in different airspace environments. The aircraft must go through multiple flight stages such as low-speed, transonic, supersonic, and even hypersonic flight. The belly of the fuselage of the cross-airspace speed domain variant aircraft is accompanied by Mach number adaptive deformation in a wide speed range and airspace. The fuselage is smooth, continuous, and compliant. It can effectively increase the fuel capacity of the aircraft and can more accurately meet the fuel and aerodynamic requirements. In the low-speed stage, the fuselage has a bulging configuration, good lift characteristics, and can carry a large amount of fuel; in the high-speed stage, the fuselage shrinks to a straight line, reducing aerodynamic resistance and reducing the thickness of the skin. The flexible skin adapts to the deformation of the variant aircraft through compliant changes, which can achieve the coordination of large structural load and deformation of the adaptive cross-airspace / speed domain aircraft in flight. The flexible skin adapts to the requirements of the fuselage variant, realizes flexible deformation, intelligent drive and perception, and the research is innovative.

[0003] Most of the existing patents related to aircraft skins, especially aircraft skin structures suitable for hypersonic flight, are material inventions based on thermal protection functions and do not have deformation drive and self-sensing capabilities. The present invention targets the deformation needs of high-speed aircraft fuselages, and can achieve both thermal protection under extreme thermal conditions and autonomous deformation drive and structural state perception, which is of great significance for the future development of hypersonic variant aircraft. Summary of the invention

[0004] The purpose of the present invention is to design an adaptive skin structure suitable for a cross-space speed domain variant aircraft, so that the aircraft can achieve high temperature protection under hypersonic flight conditions, and at the same time can achieve adaptive active deformation and a flexible skin structure with self-sensing capabilities.

[0005] In response to the adaptive deformation requirements of cross-space speed range aircraft, a flexible adaptive skin structure suitable for extreme hypersonic environments is proposed with the belly of the aircraft fuselage as the object. The skin structure is a multi-layer form, and from the outside to the inside are a thermal insulation protection layer, a flexible skin matrix, a sensor layer, and a load-bearing and driving layer; among them, the outermost layer adopts a fiber sandwich structure of alumina fiber reinforced alumina composite material coated with aerogel as the thermal insulation protection layer; a high-temperature resistant carbon fiber elastic matrix composite material is used as the flexible skin matrix; the inner load-bearing and driving layer is integrated with a honeycomb cell structure driven by an integrated high-temperature shape memory alloy wire; an optical fiber sensor is embedded between the flexible skin matrix and the load-bearing and driving layer, and the optical fiber sensor realizes direct strain measurement, and the skin thickness change is calculated through the strain measurement value; the adaptive active flexible deformation of the skin of the cross-space speed range aircraft in the hypersonic flight stage can be realized, which has important application value in the field of cross-space speed range aircraft skin design.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] An adaptive skin structure suitable for a cross-airspace speed domain variant aircraft, characterized in that, from the outside to the inside, there are a thermal insulation protection layer 1, a flexible skin matrix 2, a sensor layer 3, and a load-bearing and driving layer 4; the thermal insulation protection layer 1 and the flexible skin matrix 2 are bonded together; the flexible skin matrix 2 and the load-bearing and driving layer 4 are bonded together; and the sensor layer 3 is embedded between the flexible skin matrix 2 and the load-bearing and driving layer 4.

[0008] The heat-insulating protective layer 1 is a sandwich structure, including an alumina fiber reinforced alumina composite material layer 102 and an aerogel fiber 101 ; the alumina fiber reinforced alumina composite material 102 covers the aerogel fiber 101 .

[0009] The flexible skin matrix 2 is made of a high temperature resistant carbon fiber elastic matrix 103 composite material, which is prepared into a tubular form, and a plurality of tubular structures are closely connected and arranged.

[0010] The sensing layer 3 uses optical fiber sensors 104 as sensing elements. The optical fiber sensors 104 are evenly distributed in parallel with an interval of 30 to 50 cm.

[0011] The optical fiber sensor 104 is a FP cavity optical fiber sensor.

[0012] The bearing and driving layer 4 adopts a honeycomb cell structure 105 driven by an integrated high-temperature shape memory alloy wire 106 as a supporting and driving structure to achieve adaptive deformation of the skin.

[0013] The honeycomb cell structure 105 is made of carbon fiber composite material, the side length of the honeycomb cell structure 105 is 3 to 5 cm, and multiple honeycomb cell structures are connected by an integrated molding method; high-temperature shape memory alloy wires 106 are integrated at intervals of the honeycomb cell frame in the normal direction of the skin, and the shape memory alloy wires 106 and the honeycomb cells are bonded.

[0014] A method for adaptive skin structure deformation and driving for cross-space speed domain variant aircraft.

[0015] The honeycomb cell structure 105 is driven by the high-temperature shape memory alloy wire 106. After being insulated by the heat insulation protection layer 1, the internal temperature of the load-bearing and driving layer 4 reaches 70°C to 80°C, which meets the temperature at which the high-temperature shape memory alloy wire 106 is deformed, thereby realizing active deformation of the honeycomb cell structure 105. When the shape memory alloy wire 106 is heated, the shape memory alloy wire 106 contracts, and the flexible skin is in a contracted state, so that the belly of the aircraft fuselage contracts, so that the fuselage is in a straight state during high-speed flight, thereby reducing the aerodynamic resistance of the aircraft. When the shape memory alloy wire 106 is cooled, the shape memory alloy wire 106 stretches, and the flexible skin is in an extended state, so that the belly of the aircraft fuselage bulges, the skin thickness is large, the fuselage bulges, and the lift characteristics are good. The control of different states of fuselage bulging and contraction is realized through the heating and cooling deformation of the shape memory alloy wire 106.

[0016] Beneficial effects of the present invention

[0017] Compared with the prior art, the present invention has the following characteristics:

[0018] 1. The skin structure has multiple functions such as deformation, thermal protection, integrated load-bearing and driving, and self-sensing;

[0019] 2. The shape memory alloy is heated by using the temperature after insulation, without the need for an external heater, which has the advantages of light weight and low power consumption; BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the flexible skin of a cross-airspace speed domain variant aircraft;

[0021] Among them: 1- thermal insulation protection layer, 2- flexible skin matrix, 3- sensing layer, 4- load-bearing and driving layer, 101- aerogel fiber, 102, alumina fiber reinforced alumina composite material layer, 103- high temperature resistant carbon fiber elastic matrix, 104- optical fiber sensor, 105- honeycomb cell structure, 106- shape memory alloy wire. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0023] like Figure 1As shown, an adaptive skin structure suitable for a cross-airspace speed domain variant aircraft is characterized in that, from the outside to the inside, there are a thermal insulation protection layer 1, a flexible skin matrix 2, a sensor layer 3, and a load-bearing and driving layer 4; the thermal insulation protection layer 1 and the flexible skin matrix 2 are bonded together; the flexible skin matrix 2 and the load-bearing and driving layer 4 are bonded together; and the sensor layer 3 is embedded between the flexible skin matrix 2 and the load-bearing and driving layer 4.

[0024] The thermal insulation protective layer 1 is a sandwich structure, including an alumina fiber reinforced alumina composite material layer 102 and an aerogel fiber 101; the alumina fiber reinforced alumina composite material 102 covers the aerogel fiber 101, so that the thermal insulation protective layer can be deformed.

[0025] The flexible skin matrix 2 is made of a high temperature resistant carbon fiber elastic matrix 103 composite material, which is prepared into a tubular form. Multiple tubular structures are closely connected and arranged, which is conducive to the bulging and shrinking deformation of the skin.

[0026] The sensing layer 3 uses optical fiber sensors 104 as sensing elements, preferably FP cavity optical fiber sensors. The optical fiber sensors 104 are evenly distributed in parallel with an interval of 30 to 50 cm. The optical fiber sensors can measure structural strain. On the premise of determining the position of the optical fiber sensor, the curvature of the measuring point is measured to construct the curved shape, thereby calculating the skin thickness.

[0027] The bearing and driving layer 4 uses a honeycomb cell structure 105 driven by an integrated high-temperature shape memory alloy wire 106 as a support and driving structure to achieve adaptive deformation of the skin. The honeycomb cell structure 105 is made of carbon fiber composite material, the side length of the honeycomb cell structure 105 is 3 to 5 cm, and multiple honeycomb cell structures are connected by an integrated molding method; the honeycomb cell frame intervals are integrated with high-temperature shape memory alloy wires 106 in the normal direction of the skin, and the shape memory alloy wires 106 and the honeycomb cells are bonded.

[0028] The working principle is:

[0029] The thermal insulation protection layer 1 adopts a sandwich structure, with aerogel fibers 101 wrapped by alumina fiber reinforced alumina composite materials 102; the flexible skin matrix 2 adopts high-temperature resistant carbon fiber elastic matrix composite materials 103, which are tightly connected and arranged in a tubular shape, which is conducive to the bulging and shrinkage deformation of the skin; the load-bearing and driving layer 4 adopts a honeycomb cell structure 105 driven by an integrated high-temperature shape memory alloy wire 106 as a support and driving structure to realize active deformation of the skin; optical fiber sensors 104 are buried between the flexible skin matrix 2 and the load-bearing and driving layer 4, and multiple optical fiber sensors 104 are arranged in parallel and evenly, which can realize the measurement of strain and deformation in a high temperature environment.

[0030] The bearing and driving layer 4 adopts a honeycomb cell structure 105 as a support body. The honeycomb cell structure 105 has the advantages of high strength, high rigidity, good stability, etc. It has good load-bearing performance and can withstand a certain external load. The honeycomb cell structure 105 adopts carbon fiber composite material. The side length of the honeycomb cell structure 105 is 3 to 5 cm. Multiple honeycomb cell structures 105 are connected by an integrated molding method; high-temperature shape memory alloy wires 106 are integrated on the frame of the honeycomb cell structure 105 as a driver, and the high-temperature shape memory alloy wires 106 are arranged at intervals on the frame of the honeycomb cell structure 105 in the normal direction of the skin by gluing. The honeycomb cell structure 105 is driven by the high-temperature shape memory alloy wire 106. After being insulated by the heat insulation protection layer 1, the internal temperature of the load-bearing and driving layer 4 reaches 70°C to 80°C, which meets the temperature at which the high-temperature shape memory alloy wire 106 is deformed, thereby realizing active deformation of the honeycomb cell structure 105. When the shape memory alloy wire 106 is heated, the shape memory alloy wire 106 contracts, and the flexible skin is in a contracted state, so that the belly of the aircraft fuselage contracts, so that the fuselage is in a straight state during high-speed flight, thereby reducing the aerodynamic resistance of the aircraft. When the shape memory alloy wire 106 is cooled, the shape memory alloy wire 106 stretches, and the flexible skin is in an extended state, so that the belly of the aircraft fuselage bulges, the skin thickness is large, the fuselage bulges, and the lift characteristics are good. The control of different states of fuselage bulging and contraction is realized through the heating and cooling deformation of the shape memory alloy wire 106.

[0031] The optical fiber sensor is embedded between the flexible skin matrix and the load-bearing and driving layers of the present invention. Preferably, an FP cavity optical fiber sensor is selected and arranged between the flexible skin matrix and the load-bearing and driving layers by an embedding method. The optical fiber sensor can measure the structural strain. On the premise of determining the position of the optical fiber sensor, the curvature of the measuring point is measured to construct the bending shape, thereby calculating the skin thickness.

[0032] The above is only a preferred embodiment of the present invention, and the present invention should not be limited to the contents disclosed in the embodiment and the drawings. Any equivalent or modification completed without departing from the spirit disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. An adaptive skin structure suitable for a cross-airspace speed domain variant aircraft, characterized in that: From the outside to the inside, there are a heat-insulating protective layer (1), a flexible skin substrate (2), a sensing layer (3), and a bearing and driving layer (4); the heat-insulating protective layer (1) and the flexible skin substrate (2) are bonded together; the flexible skin substrate (2) and the bearing and driving layer (4) are bonded together; and the sensing layer (3) is embedded between the flexible skin substrate (2) and the bearing and driving layer (4).

2. The adaptive skin structure suitable for a cross-airspace speed domain variant aircraft according to claim 1 is characterized in that: The heat insulation protection layer (1) is a sandwich structure, comprising an alumina fiber reinforced alumina composite material layer (102) and an aerogel fiber (101); the alumina fiber reinforced alumina composite material (102) covers the aerogel fiber (101).

3. The adaptive skin structure suitable for a cross-airspace speed domain variant aircraft according to claim 1 is characterized in that: The flexible skin matrix (2) is made of a high-temperature resistant carbon fiber elastic matrix (103) composite material, which is prepared into a tubular form, and a plurality of tubular structures are closely connected and arranged.

4. The adaptive skin structure suitable for a cross-airspace speed domain variant aircraft according to claim 1 is characterized in that: The sensing layer (3) uses optical fiber sensors (104) as sensing elements, and the optical fiber sensors (104) are evenly distributed in parallel with an interval of 30 to 50 cm.

5. The adaptive skin structure suitable for a cross-airspace speed domain variant aircraft according to claim 4 is characterized in that: The optical fiber sensor (104) is a FP cavity optical fiber sensor.

6. The adaptive skin structure suitable for a cross-airspace speed domain variant aircraft according to claim 1, characterized in that: The bearing and driving layer (4) adopts a honeycomb cell structure (105) driven by an integrated high-temperature shape memory alloy wire (106) as a supporting and driving structure to achieve adaptive deformation of the skin.

7. The adaptive skin structure suitable for a cross-airspace speed domain variant aircraft according to claim 6 is characterized in that: The honeycomb cell structure (105) is made of carbon fiber composite material, the side length of the honeycomb cell structure (105) is 3 to 5 cm, and multiple honeycomb cell structures are connected by an integrated molding method; high-temperature shape memory alloy wires (106) are integrated at intervals in the honeycomb cell frame in the normal direction of the skin, and the shape memory alloy wires (106) and the honeycomb cells are bonded.

8. The method for adaptive skin structure deformation and driving of a cross-space speed domain variant aircraft according to any one of claims 1 to 7, characterized in that: The honeycomb cell structure (105) is driven by a high-temperature shape memory alloy wire (106). After being insulated by a heat-insulating protective layer (1), the internal temperature of the load-bearing and driving layer (4) reaches 70°C to 80°C, which satisfies the temperature at which the high-temperature shape memory alloy wire (106) deforms, thereby realizing active deformation of the honeycomb cell structure (105); when the shape memory alloy wire (106) is heated, the shape memory alloy wire (106) contracts, and the flexible skin is in a contracted state, so that the belly of the aircraft fuselage contracts, so that the fuselage is in a straight state in a high-speed flight state, thereby reducing the aerodynamic resistance of the aircraft; when the shape memory alloy wire (106) is cooled, the shape memory alloy wire (106) stretches, and the flexible skin is in a stretched state, so that the belly of the aircraft fuselage bulges, the skin thickness is large, the fuselage bulges, and the lift characteristics are good; and the control of the different states of fuselage bulging and contraction is realized through the heating and cooling deformation of the shape memory alloy wire (106).

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