Variable camber inflatable folding wing based on electro-responsive shape memory polymer and control method

Abstract

The application provides a variable dihedral angle inflatable folding wing based on an electric response shape memory polymer and a control method, which comprises a wing shell, a control system and a pump; the wing shell comprises a framework, an elastic body electrothermal layer and a flexible skin, the framework comprises a wing rib and a spar, and the spar is provided with an electric response shape memory polymer; an upper air bag and a lower air bag which are not conductive to each other are symmetrically installed inside the wing contour between adjacent wing ribs; adjacent upper air bags are connected to each other, and adjacent lower air bags are connected to each other; the upper air bag and the lower air bag at one end of the wing contour are connected with the pump respectively; the control system controls the electric response shape memory polymer to conduct electricity, so that the spar generates thermal deformation; and the control system controls the pump to make the upper air bag or the lower air bag negative pressure, so as to change the upper or lower dihedral angle of the wing. The application can realize variable dihedral angle under different flight requirements.

Description

Technical Field

[0001] This invention relates to the field of aerospace wings or shape memory materials, and more particularly to an inflatable folding wing with variable dihedral angle based on an electroresponsive shape memory polymer and a control method thereof. Background Technology

[0002] The angle of installation refers to the tilt angle of the wing relative to the longitudinal axis of the fuselage, mainly including the dihedral and anhedral angles. These two angles have a significant impact on the aircraft's flight performance and stability. The dihedral angle is the angle between the lower surface of the wing and a plane perpendicular to the aircraft's vertical axis. The purpose of the dihedral angle is to increase aircraft stability. When affected by unstable airflow, the dihedral angle helps the aircraft automatically recover its stable state. In addition, the dihedral angle also improves the aircraft's pitch stability, allowing it to quickly return to normal flight after being disturbed. The anhedral angle is the angle between the upper surface of the wing and a plane perpendicular to the aircraft's vertical axis. The function of the dihedral angle is to reduce the aircraft's stability, thereby improving its maneuverability. When roll maneuvers are required, the dihedral angle helps reduce the stabilizing forces on the aircraft, making it easier to perform roll maneuvers and improving maneuverability.

[0003] However, existing dihedral wings still have many shortcomings and face numerous problems in practical applications. The biggest problem is that they cannot be easily and arbitrarily changed and precisely controlled. An excessively large or poorly designed dihedral angle can lead to a serious loss of flight controllability, even affecting basic operations such as normal steering; similarly, an excessively large dihedral angle can lead to insufficient aircraft stability and difficulty in fine-tuning. This also means that pilots need to adjust the dihedral angle through the flight control system to maintain stable flight, but the adjustment system is usually mechanical and driven as a whole, with a complex design that makes maintenance difficult and cannot be easily retracted; at the same time, the mechanical structure is bulky and cannot be easily retracted; its weight seriously affects the aircraft's onboard performance and cannot be applied to lightweight, small-to-medium-sized flight devices. In addition, as the installation angle, the dihedral angle means that most existing control system designs only involve unidirectional control, such as adjustments can only be made based on the dihedral angle or the dihedral angle, and it is impossible to switch between dihedral and dihedral angles simultaneously or to finely control the dihedral angle.

[0004] In response to these adaptability and operational requirements, as well as market demands, researchers have gradually begun to design different dihedral design schemes for airfoils.

[0005] The prior art discloses a dual-drive variable span and dihedral wing, which solves the problem that existing low-speed aircraft cannot simultaneously achieve wing span extension and spanwise bending. This invention is mainly used for variable span and dihedral wing. Although it can also achieve dihedral function, it can only be applied to low-speed aircraft. It also uses a large number of mechanical structures, which are too bulky and cannot be folded. It cannot meet the current requirements for lightweight and miniaturization of aircraft such as inflatable aircraft.

[0006] For example, the prior art discloses a multi-wing model aircraft wing anhedral synchronous adjustment device. The wing anhedral adjustment is precise. Different types of wings can be quickly installed and the anhedral angle can be precisely adjusted synchronously through the wing adjustment mechanism. The fuselage adjustment mechanism can reliably install the fuselage. It is convenient, reliable, quick and stable to assemble. Although it achieves precise control of the anhedral angle, it cannot switch between the anhedral and dihedral angles. Its application scenarios are limited and it cannot cope with various flight conditions.

[0007] Existing technology discloses a wing that can fold and unfold along its span. A drive assembly drives a first and a second adjusting member to rotate around a rotating member to achieve folding, unfolding, and dihedral adjustment of the wing. This wing has advantages such as high cruise efficiency, large payload, strong control performance, good anti-interference capability, low takeoff and landing site requirements, and high wing structural rigidity and strength. However, its wing shape is limited, restricting its application to vertical takeoff and landing aircraft; while it has a variable dihedral shape, it cannot be fine-tuned and is fixed at 20°, limiting its application scenarios. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an inflatable folding wing with variable dihedral angle based on an electroresponsive shape memory polymer and a control method thereof. This minimizes mechanical structures, is suitable for lightweighting and simplification of small and medium-sized aircraft, and is easy to maintain. It can achieve dihedral angle adjustment to meet different flight requirements, selecting an upward dihedral angle for lateral stability and a downward dihedral angle for longitudinal maneuverability. Furthermore, it allows for fine-tuning of the wing dihedral angle based on specific environmental conditions, in addition to selecting flight characteristics. The wing structure can also be folded to reduce space occupation.

[0009] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0010] A variable-angle inflatable folding wing based on an electroresponsive shape memory polymer, comprising a wing shell, a control system, and a pump;

[0011] The wing shell includes a skeleton, an elastomer electrothermal layer, and a flexible skin. The skeleton includes ribs and spars. Several ribs arranged side by side form the outer contour skeleton of the wing through spars on both sides. The outer contour of the skeleton is wrapped with a flexible skin. The spars are provided with an electroresponsive shape memory polymer to deform the spars.

[0012] Symmetrical, non-conductive upper and lower airbags are installed inside the outer contour of the wing between adjacent wing ribs; adjacent upper airbags are interconnected, and adjacent lower airbags are interconnected; the upper and lower airbags at one end of the outer contour of the wing are respectively connected to a pump; the control system controls the electrical response shape memory polymer to conduct electricity, causing thermal deformation of the wing spars; the control system controls the pump to create negative pressure in the upper or lower airbags to change the dihedral angle of the wing.

[0013] Furthermore, the wing spar has a built-in carbon fiber electrothermal layer, which serves as a primary electrothermal layer; an elastomer electrothermal layer is provided on the inner side of the wing spar, which is made of an electroresponsive shape memory polymer; the elastomer electrothermal layer serves as a secondary electrothermal layer, and the control system selectively electrostimulates the primary and secondary electrothermal layers to deform the wing spar.

[0014] Furthermore, the elastomer electrothermal layer contains silver nanowires, which serve as the stimulation source for the elastomer electrothermal layer; the elastomer inside the elastomer electrothermal layer is a tensile elastomer with inward contraction prestress, providing a secondary driving force for the shape control of the wing's dihedral angle, and is used for fine control of the dihedral angle.

[0015] Furthermore, the wing spar has a trapezoidal shape memory material cross-section, and the center of the trapezoidal wing spar is provided with an electrothermal layer of carbon fiber material; by electrically stimulating the electrothermal layer of carbon fiber material, the trapezoidal shape memory material generates a shape recovery force, thereby deforming the wing spar.

[0016] Furthermore, the trapezoidal long side of the trapezoidal spar is located on the outer side of the wing, and the trapezoidal short side of the trapezoidal spar is located on the inner side of the wing, so that the structural stress is directed towards the centerline of the wing.

[0017] Furthermore, the pump is a variable temperature high-pressure air pump used to output hot or cold air. The pump draws in air to create a negative pressure in the upper or lower airbag, and uses the negative pressure to generate a contraction force in the upper or lower airbag, providing the main driving force for driving the wing to deform upward or downward at the dihedral angle, and is used for coarse control of the dihedral angle.

[0018] Furthermore, the upper airbag is connected to the upper spar of the wing's outer contour frame, and the lower airbag is connected to the lower spar of the wing's outer contour frame. The hot air output by the pump exchanges heat with the frame. When the upper and lower airbags contract, they drive the wing's outer contour frame to contract and fold.

[0019] Furthermore, the outer contour of the wing is a NACA airfoil structure; the control system controls the contraction of the upper or lower airbag to change the dihedral angle of the wing from -20° to 20°.

[0020] A control method for an inflatable folding wing with variable dihedral angle based on an electroresponsive shape memory polymer includes the following steps:

[0021] Rough control of dihedral angle: The control system electrically stimulates the primary electrothermal layer to heat one side of the wing spars and reduce its modulus. The pump is used to extract air from the corresponding air bladder in one side of the wing spars, creating a pressure difference between the upper and lower air bladders in the outer contour frame of the wing. This pressure difference causes one side of the wing spars to bend and deform towards the lower pressure side.

[0022] Precise control of the reverse angle: The control system electrically stimulates the secondary electrothermal layer, and the contraction of the elastomer in the elastomer electrothermal layer generates inward contraction prestress, causing a small deformation of one side of the wing beam to the outside.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The variable dihedral inflatable folding wing based on electroresponsive shape memory polymer described in this invention uses 4D printing technology to complete the design of the wing skeleton and deformable structure, which greatly simplifies the production process of common folding inflatable wings, eliminates a large number of complex mechanical structures, simplifies the structural design, and reduces production and maintenance costs. At the same time, it can be added and modified as needed according to the application of the structure to meet the requirements of lightweighting and simplification.

[0025] 2. The inflatable folding wing with variable dihedral angle based on electroresponsive shape memory polymer described in this invention comprises a carbon fiber electrothermal layer built into the wing spars, which serves as a primary electrothermal layer and also reinforces the frame; an elastomer electrothermal layer is provided on the inner side of the wing spars, the material of which is an electroresponsive shape memory polymer; the elastomer electrothermal layer serves as a secondary electrothermal layer; the wing can reduce the modulus of a single wing spars structure by heating it according to the electrical stimulation received by the primary electrothermal layer on a single wing surface, providing space for subsequent dihedral operation. First, using the pressure difference method, the cold and heat pump negative pressure function is activated to appropriately extract some air from the airbag on the low-modulus deformation side, causing the airbag on the deformation side to contract, thereby causing the wing to deform towards the side with lower modulus, roughly controlling the deformation direction and angle of the wing's dihedral angle; then, by utilizing the contraction of the elastomer electrothermal layers attached to the wing spars on different wing sides, the wing structure on the same side is tightened, finely controlling the angle of the wing's dihedral angle. For example, when switching to dihedral angle, electrical stimulation softens the upper wing sparsity to reduce its modulus, then the heat pump negative pressure function is activated to cause the corresponding upper airbag on the upper wing sparsity to contract and deform, causing the wing to change to a dihedral angle. Then, electrical stimulation of the secondary electrothermal layer activates the contraction of the stretch elastomer, precisely controlling the dihedral angle. Similarly, when switching to anhedral angle, electrical stimulation softens the upper wing sparsity to reduce its modulus, then the heat pump negative pressure function is activated to cause the corresponding lower airbag on the lower wing sparsity to contract and deform, causing the wing to change to anhedral angle. Then, electrical stimulation of the secondary electrothermal layer activates the contraction of the stretch elastomer, precisely controlling the anhedral angle. Through two stages of coarse and fine-tuning control, the dihedral stability requirement or the anhedral maneuverability requirement during flight can be precisely switched and selected, improving the adaptability of the inflatable aircraft to different flight environments and application requirements. This allows for dihedral angle changes when facing different flight needs, selecting between dihedral angles for lateral stability and anhedral angles for longitudinal maneuverability, and performing precise control after the dihedral / anhedral angle selection.

[0026] 3. The variable dihedral inflatable folding wing based on electroresponsive shape memory polymer described in this invention uses upper and lower airbags installed between each spaced wing rib. The left and right adjacent airbags are connected to each other through a connecting valve. An additional connecting valve is placed at the wing tip. The airbag at the wing root is connected to a heat pump. The heat pump outputs high-temperature compressed air and negative pressure, which, in conjunction with the connecting valve and its control circuit, heats up the airbag and then evacuates it, thereby achieving rapid folding of the wing structure.

[0027] 4. The variable dihedral inflatable folding wing based on electroresponsive shape memory polymer described in this invention reduces mechanical structure, achieves volume reduction of the variable dihedral wing, simplifies complex mechanics, simplifies the production process, reduces weight, simplifies structural design, and reduces production and maintenance costs; it meets the controllability and adaptability requirements of flight, and the lightweight design allows for the selection of the upper / lower dihedral angle of the wing. Based on the determined dihedral form, the angle of the wing dihedral can be finely adjusted, making control more operable and adaptable; it also enables the folding of the wing structure, reducing space occupation. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a structural diagram of an inflatable folding wing based on an electroresponsive shape memory polymer with variable dihedral angle, as described in this invention.

[0030] Figure 2 This is a schematic diagram showing the position of the upper airbag described in this invention.

[0031] Figure 3 This is a schematic diagram of the connection between the skeleton and skin structure described in this invention.

[0032] Figure 4 This is a schematic diagram of the wing beam structure described in this invention.

[0033] Figure 5 This is a schematic diagram of the elastomer electrothermal layer described in this invention.

[0034] Figure 6 This is a schematic diagram of the arrangement of the wing beam and the electrothermal layer according to the present invention.

[0035] Figure 7 This is a schematic diagram illustrating the wing folding process described in this invention.

[0036] Figure 8 This is a schematic diagram showing the installation of the connecting valve, pump, and power supply described in this invention. It also shows the state of the split-type airbag during inflation.

[0037] Figure 9 This is a schematic diagram of the wing deformation described in this invention. Figure 9 (a) is a schematic diagram of the process of changing the upper angle; Figure 9 (b) is a straight wing shape; Figure 9 (c) is a schematic diagram of the variable downward angle process.

[0038] In the picture:

[0039] 1-Frame; 1-1-Wing rib; 1-2-Wing spars; 2-Elastomer heating layer; 3-Upper airbag; 4-Flexible skin; 5-Connecting valve; 6-Pump; 7-Power supply. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] like Figure 1 and Figure 2 As shown, the variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer of the present invention includes a wing shell, a control system, and a pump 6;

[0044] The wing shell includes a frame 1, an elastomer electrothermal layer 2, and a flexible skin 4. The frame 1 includes ribs 1-1 and spars 1-2. The shape of the ribs 1-1 is the cross-sectional shape of the wing. Several ribs 1-1 are arranged at intervals and connected to each other through the spars 1-2 on the upper and lower sides to form the outer contour frame of the wing. The spars 1-2 and ribs 1-1 have matching grooves at their connection points, allowing the spars 1-2 to fit well into the ribs 1-1, so that the intersection of the spars 1-2 and ribs 1-1 forms a complete plane. The spars 1-2 and ribs 1-1 are connected by bonding with UV-cured adhesive at the grooves, followed by UV irradiation for 3-5 minutes, ultimately forming the mesh-like frame of the wing's outer contour. The spar 1-2 connecting the upper sides of several wing ribs 1-1 is called the upper spar, and the spar 1-2 connecting the lower sides of several wing ribs 1-1 is called the lower spar. The flexible skin 4 is installed on the outer contour of the frame 1 in a segmented manner, and different parts of the flexible skin 4 are bonded together with adhesive to form a whole. The flexible skin 4 is made of flexible TPU skin, which has good tensile and heat shrink resistance and can resist wrinkling under high temperature deformation. The shape of the outer contour frame of the wing is a NACA airfoil structure; the spar 1-2 is provided with an electroresponsive shape memory polymer to cause the spar 1-2 to deform; the power supply 7 can electrically stimulate the electroresponsive shape memory polymer.

[0045] A non-communicating upper airbag 3 and a lower airbag are symmetrically installed inside the outer contour of the wing between adjacent ribs 1-1; adjacent upper airbags 3 are interconnected via a connecting valve 5, and adjacent lower airbags are interconnected via a connecting valve 5; as shown Figure 2 and Figure 8As shown, several upper airbags 3 are connected in series via connecting valves 5. The upper airbag 3 at one end of the wing's outer contour is connected to a pump 6; the upper airbag 3 at the other end of the wing's outer contour is equipped with a connecting valve 5 that communicates with the atmosphere, used for venting or acting as a safety valve. Several lower airbags are connected in series via connecting valves 5. The lower airbag at one end of the wing's outer contour is connected to a pump 6; the lower airbag at the other end of the wing's outer contour is equipped with a connecting valve 5 that communicates with the atmosphere, used for venting or acting as a safety valve. The control system on the outermost part of the wing's outer contour controls the electrical response shape memory polymer to conduct electricity with the power supply 7, causing thermal deformation of the wing spars 1-2; the control system controls the pump 6 to generate negative pressure in either the upper or lower airbags, used to change the wing's dihedral angle. The pump 6 is a variable temperature high-pressure air pump used to output hot or cold air. Pump 6 draws in air, creating negative pressure in the upper or lower airbag 3. This negative pressure causes the upper or lower airbag 3 to contract, providing the main driving force for the upward or downward dihedral deformation of the wing, and is used for coarse control of the dihedral angle. Furthermore, the connecting valve 5 is automatically controlled according to the start / stop of pump 6 and the selection of hot / cold or negative pressure, ensuring consistent air pressure within the upper or lower airbag 3. The control system controls the contraction of the upper or lower airbag 3, changing the wing dihedral angle range to -20° to 20°, meeting the requirements of flight dynamics parameters and statistical values ​​for both dihedral and downward angles.

[0046] like Figure 3 , Figure 4 and Figure 5 As shown, the wing spar 1-2 has a built-in carbon fiber electrothermal layer, which serves as a primary electrothermal layer; the inner side of the wing spar 1-2 is provided with an elastomer electrothermal layer 2, which is made of an electroresponsive shape memory polymer; the elastomer electrothermal layer 2 serves as a secondary electrothermal layer, and the control system selectively electrostimulates the primary and secondary electrothermal layers to deform the wing spar 1-2.

[0047] The wing spade 1-2 has a trapezoidal cross-section made of shape memory material, with a carbon fiber electrothermal layer at its center. By electrically stimulating this electrothermal layer, the shape memory material can deform into a highly elastic state when the temperature reaches its glass transition temperature (Tg), softening the structure while simultaneously generating shape-restoring force, thus deforming the wing spade 1-2. The wing spade 1-2 is printed using coaxial 4D printing, forming a continuous reinforcing carbon fiber axis at its center. This provides high structural strength and functions as an electrothermal layer, eliminating the need for additional patching. The trapezoidal cross-section of the wing spade 1-2, with the longer side of the trapezoid on the outer side of the wing and the shorter side on the inner side, ensures that the structural stress is directed towards the wing centerline. Figure 6 As shown.

[0048] like Figure 4 and Figure 5 As shown, the elastomer electrothermal layer 2 contains silver nanowires, which serve as the stimulation source for the elastomer electrothermal layer 2. The elastomer inside the elastomer electrothermal layer 2 is a tensile elastomer with inward contraction prestress, providing a secondary driving force for the shape control of the wing's dihedral angle, used for fine dihedral control. The connection between the wing spars 1-2 and the elastomer electrothermal layer 2 is achieved by bonding, using an adhesive for adhesion. The elastomer electrothermal layer 2 is bonded to the inner side of the upper and lower wing spars 1-2, i.e., at the short side of the trapezoidal cross-section, ensuring that the direction of the shape recovery stress points towards the interior of the wing structure.

[0049] The elastomer of the electrothermal layer 2 comprises polypropylene glycol (PPG), 4,4'-methylenebis(phenyl isocyanate), and 4,4'-methylenebis(phenylurea) (MPU), synthesized via a one-pot synthesis method. Upon receiving external electrical stimulation, the elastomer electrothermal layer 2 responds by generating heat through an electrothermal reaction, causing the local temperature to rise to the glass transition temperature Tg. This softens the structure, stretches the elastomer, and causes it to contract, thus deforming the wing frame 1. The primary electrothermal layer embedded within the wing spars 1-2 provides electrical conductivity; the secondary electrothermal layer 2 further enhances conductivity and deformability, forming a complete electroresponsive shape memory polymer. This facilitates graded control, allows for remote actuation, and offers advantages such as higher response speed and precision.

[0050] The upper airbag 3 is connected to the upper spar of the outer contour frame of the wing, and the lower airbag is connected to the lower spar of the outer contour frame of the wing. The hot air output by the pump 6 exchanges heat with the frame 1. When the upper airbag 3 and the lower airbag contract, they drive the outer contour frame of the wing to contract and fold.

[0051] The shape memory process of spar 1-2 is as follows: During deformation, the primary heating layer inside spar 1-2 is heated to above the glass transition temperature Tg. The elastomer heating layer 2 is energized and heated to above the glass transition temperature Tg as well. The structure softens to a highly elastic state, and the elastomer exerts its contractile force, causing the highly elastic spar 1-2 to deform. At the same time, internal structural stress is applied to spar 1-2. When the structural deformation is complete, the power is cut off, the temperature is reduced, and the deformed shape is maintained. During recovery, the primary heating layer inside spar 1-2 is heated again to above the glass transition temperature Tg. The elastomer heating layer 2 is not activated, and the internal structural stress of spar 1-2 is released, allowing the wing structure to return to its initial state.

[0052] Example 1

[0053] In this embodiment, during normal operation, the wing is in a straight wing configuration with a wingspan of 500mm and a chord length of 200mm. Flight is conducted in a normal flight mode, with the wing internal pressure set to 120kPa. When encountering strong crosswinds or other conditions requiring lateral stability, the dihedral angle is set to 10°. Conversely, when encountering sideslip or other conditions requiring maneuverability and fine control of the dihedral angle is needed, the required concave angle is set to 10°. The following example operation is performed:

[0054] like Figure 9 As shown, the upper wing spars can change their dihedral shape according to the contraction state of the upper airbag 3 and the energization state of the elastomer heating layer 2. Similarly, the lower wing spars can change their dihedral shape according to the contraction state of the lower airbag and the energization state of the elastomer heating layer 2. When lateral stability needs to be selected and fine control is required, the dihedral angle can be adjusted as follows: Figure 9 As shown in (a), firstly, the primary electrothermal layer of the upper wing spars is energized with a voltage of 20V and a current of 0.17A for 34.8s. Heat is generated through the electrothermal effect, raising the temperature of the upper wing spars to the glass transition temperature. The shape memory material changes from a hard glassy state to a flexible, highly elastic state, softening the frame and providing deformation space for subsequent dihedral adjustments. Then, by opening the connecting valve 5 and activating the pump 6 to generate negative pressure, air is pumped out of the upper airbag 3 to 77kPa. Utilizing the modulus difference between the upper and lower frames in the current state, when the softened upper wing spars are subjected to inward contraction pressure, the low-modulus upper wing spars will deform, causing the entire structure to bend upwards, thereby causing the entire wing to change its dihedral shape by 9°. After coarse adjustment, the pump 6 is turned off, while the connecting valve 5 remains open. Finally, the patch is attached to the upper wing spars 1-2. Electrical stimulation is applied to the electrothermal layer 2 within the elastomer, with a voltage of 15V, a current of 0.13A, and a duration of 17.2s. This activates the tensile elastomer within the elastomer electrothermal layer 2 through the electrothermal effect. Due to the shape memory recovery effect, the elastomer actively transforms towards the printed shape and contracts, generating a centripetal contraction force. This force continues to pull the upper wing sparsity upward, causing it to bend and contract. The angle change produced by the contraction is 1°. After reaching the required dihedral angle of 10°, the electrical stimulation applied to the upper wing sparsity and the elastomer electrothermal layer 2 is removed. The wingtip connecting valve 5 is opened, and the pump 6 is turned on again to introduce cold compressed air to assist the upper wing sparsity and the elastomer electrothermal layer 2 in rapidly cooling down, thus fixing the wing shape at the required dihedral angle. After shaping, the pump 6 and the connecting valve 5 are closed. At this point, the cooled and shaped upper wing sparsity contains a shape memory recovery force and an internal stress that recovers from deformation to the initial printed state.

[0055] When it is necessary to select the longitudinal maneuverability of flight and perform fine control, the diagram of the variable dihedral angle is as follows: Figure 9As shown in (c), firstly, the primary electrothermal layer of the lower wing spars is energized with a voltage of 20V and a current of 0.17A for 38s. Heat is generated through the electrothermal effect, raising the temperature of the lower wing spars to the glass transition temperature. The shape memory material changes from a hard glassy state to a flexible, highly elastic state, softening the skeleton and providing deformation space for subsequent dihedral adjustments. Then, by opening the connecting valve 5 and activating the pump 6 to generate negative pressure, air is pumped out of the lower airbag to 75kPa. Utilizing the modulus difference between the upper and lower skeletons, when the softened lower wing spars are subjected to inward contraction pressure, the low-modulus lower wing spars deform, causing the entire structure to bend downwards, thereby changing the dihedral shape of the entire wing by 9°. After coarse adjustment, the pump 6 is turned off, while the connecting valve 5 remains open. Finally, the elastomer patch attached to the lower wing spars is electrothermated. Electrical stimulation is applied to the electrothermal layer within layer 2 at a voltage of 15V and a current of 0.13A for 25.5s. This activates the stretching elastomer within the elastomer electrothermal layer 2 through the electrothermal effect. Due to the shape memory recovery effect, the elastomer actively transforms into the printed shape and contracts, generating a centripetal contraction force. This force continues to pull the lower wing sparsity downwards, causing a 1° change in angle. Once the required dihedral angle of 10° is reached, the electrical stimulation applied to the lower wing sparsity and the elastomer electrothermal layer 2 is removed. The wingtip connecting valve 5 is opened, and pump 6 is turned on again to introduce cold compressed air to assist in the rapid cooling of the lower wing sparsity and the elastomer electrothermal layer 2. This fixes the wing shape at the required dihedral angle. After the shape is set, pump 6 and connecting valve 5 are closed. At this point, the cooled and shaped lower wing sparsity contains a shape memory recovery force and an internal stress that recovers from deformation to the initial printed state.

[0056] When need to from Figure 9 (a) The upper anti-angle deformation is completed and the state is transformed into Figure 9 (b) In the straight wing state, simply open all the connecting valves of the upper airbag 3 on the deformable side first, and then apply electrical stimulation to the upper wing spars to increase the temperature of the upper wing spars to the glass transition temperature Tg, activating the shape memory effect of the shape memory polymer. This allows the low-temperature shaping state under high temperature stress to gradually return to the initial state after printing after the external force is removed, thus making the wing shape resemble... Figure 9 (b) shows the transformation of the straight wing state to reach the initial state of the dihedral wing. Subsequently, the upper / lower dihedral shape of the wing can be reselected according to flight requirements.

[0057] In this embodiment, the wing is in a straight, deployed state during normal operation. When it is necessary to fold the wing mechanism to save space and facilitate transportation, the following example operation is performed:

[0058] like Figure 7As shown, a control switch is installed in the control room of the inflatable aircraft, which is manually controlled to select the operation of pump 6. The connecting valves 5 are controlled by a control system, which does not require manual control. When pump 6 is turned on, all valves except the connecting valves at the wingtips are open; when pump 6 is turned off, all connecting valves 5 are closed, so that each airbag is independently supported and indirectly controls the deployment, shaping and folding of the connected frame 1.

[0059] like Figure 7 As shown, when wing structure folding is required, all connecting valves 5 are opened, pump 6 is activated and outputs high-temperature compressed air, which flows through the upper and lower airbags and finally outwards from the wing. During this process, the high-temperature compressed air heats the frame 1 through heat conduction, causing the frame 1 to heat up to its glass transition temperature Tg. The shape memory material state of the frame 1 changes from a hard glassy state to a flexible, highly elastic state. After the wing frame 1 is completely softened, pump 6 is turned off, stopping the output of high-temperature compressed air; connecting valve 5 at the outer end of the wing is closed to ensure the overall airtightness of the upper and lower airbags. At this time, thanks to the airbags... Hot air, the wing frame 1 is still in a highly elastic state above the glass transition temperature Tg, with good deformation and folding ability. When the pump 6 is turned on to generate negative pressure, the hot air in the airbag can be quickly and adjustablely extracted. When the pump 6 extracts air with negative pressure, the upper airbag 3 and the lower airbag will contract, which will drive the wing frame 1 to contract and deform, and drive the entire wing structure to fold. When the negative pressure value reaches MAX, the wing folding is completed. The volume of the wing structure after contraction is much smaller than the normal volume of the wing, realizing the adjustable and controllable speed and intensity of the wing structure contraction and folding process, and realizing the active control of wing folding.

[0060] Taking the upper airbag 3 as an example, the spacing between adjacent upper airbags 3 is half the thickness of the sandwiched wing ribs 1-1, ensuring sufficient contact area between the split airbag and the frame 1 to transfer heat from the hot air inside the split airbag to assist deformation, while also ensuring sufficient contact area for the frame 1 to restrict the shape of the upper airbag 3. The upper airbag 3 and the frame 1 are connected by an adhesive, ensuring that the airbag can drive the frame to deform synchronously during inflation and folding, ensuring uniform stress. The shape of the upper airbag 3 basically matches the shape of the wing frame 1, which is beneficial for the average stress during airbag deployment and contraction, and also facilitates the frame's restriction of the airbag shape, ensuring that the shape of the flexible skin 4 is not damaged. The TPU coated fabric used in the upper airbag 3 has a tensile strength of 28MPa, a tear strength >350N / mm, and a maximum melting point of 260℃.

[0061] The pump 6 is a variable temperature high-pressure air pump, capable of outputting both cold and hot air, with an output temperature of 0-100℃ and a normal air pressure of 3.0MPa. It can also create negative pressure through reverse air intake. This ensures that the air pressure and temperature required for the deployment and folding of the upper airbag 3 are met.

[0062] The power supply 7 is a variable AC / DC variable voltage power supply.

[0063] An aircraft comprising the aforementioned variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer.

[0064] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0065] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A variable-angle inflatable folding wing based on an electroresponsive shape memory polymer, characterized in that, Includes wing shell, control system and pump (6); The wing shell includes a frame (1), an elastomer electrothermal layer (2), and a flexible skin (4). The frame (1) includes ribs (1-1) and spars (1-2). Several ribs (1-1) arranged side by side form the outer contour frame of the wing through spars (1-2) on both sides. The outer contour of the frame (1) is wrapped with the flexible skin (4). The spars (1-2) are provided with an electroresponsive shape memory polymer to cause the spars (1-2) to deform. Symmetrical upper airbags (3) and lower airbags, which are not interconnected, are installed inside the outer contour of the wing between adjacent ribs (1-1); adjacent upper airbags (3) are interconnected, and adjacent lower airbags are interconnected; the upper airbags (3) and lower airbags at one end of the outer contour of the wing are respectively connected to a pump (6), and the negative pressure driving force generated by the pump (6) on the upper airbag (3) or lower airbag is the main driving force, which is used for coarse control of the dihedral angle; carbon fiber is built into the spar (1-2). The system comprises a carbon fiber electrothermal layer, which serves as the primary electrothermal layer; an elastomer electrothermal layer (2) is provided on the inner side of the wing spar (1-2), the material of which is an electro-responsive shape memory polymer; the elastomer electrothermal layer (2) serves as the secondary electrothermal layer, and the control system selectively electrostimulates the primary and secondary electrothermal layers to deform the wing spar (1-2); the prestress generated by the electrostimulation of the elastomer electrothermal layer (2) serves as the secondary driving force for precise control of the dihedral angle; The control system controls the electrical response shape memory polymer to conduct electricity, causing thermal deformation of the wing spars (1-2); the control system controls the pump (6) to generate negative pressure in the upper airbag (3) or the lower airbag, which is used to change the dihedral angle of the wing.

2. The variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to claim 1, characterized in that, The elastomer electrothermal layer (2) contains silver nanowires, which serve as the stimulation source for the elastomer electrothermal layer (2). The elastomer inside the elastomer electrothermal layer (2) is a tensile elastomer with inward contraction prestress, which provides a secondary driving force for the shape control of the upper or lower dihedral angle of the wing and is used for fine control of the dihedral angle.

3. The variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to claim 1, characterized in that, The cross-section of the wing beam (1-2) is a trapezoidal shape memory material, and the center of the trapezoidal wing beam (1-2) is provided with an electrothermal layer of carbon fiber material; by electrically stimulating the electrothermal layer of carbon fiber material, the trapezoidal shape memory material generates a shape recovery force, thereby deforming the wing beam (1-2).

4. The variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to claim 3, characterized in that, The trapezoidal long side of the trapezoidal spar (1-2) is located on the outer side of the wing, and the trapezoidal short side of the trapezoidal spar (1-2) is located on the inner side of the wing, so that the structural stress is directed towards the centerline of the wing.

5. The variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to claim 1, characterized in that, The pump (6) is a variable temperature high pressure air pump used to output hot air or cold air. The pump (6) draws in air to form a negative pressure in the upper airbag (3) or the lower airbag. The negative pressure is used to generate a contraction force in the upper airbag (3) or the lower airbag, which provides the main driving force for driving the wing to deform upward or downward dihedral shape, and is used for rough control of dihedral.

6. The variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to claim 1, characterized in that, The upper airbag (3) is connected to the upper spar of the outer contour frame of the wing, and the lower airbag is connected to the lower spar of the outer contour frame of the wing. The hot air output by the pump (6) exchanges heat with the frame (1). When the upper airbag (3) and the lower airbag contract, they drive the outer contour frame of the wing to contract and fold.

7. The variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to claim 1, characterized in that, The outer contour of the wing is NACA airfoil structure; the control system controls the upper airbag (3) or the lower airbag to contract, changing the dihedral angle of the wing from -20° to 20°.

8. A control method for a variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer according to any one of claims 1-7, characterized in that, Includes the following steps: Rough control of dihedral angle: The control system electrically stimulates the first-level electrothermal layer to heat up one side of the wing spars (1-2) and reduce its modulus. The pump (6) is used to extract air from the corresponding air bladder in one side of the wing spars (1-2), so that the air pressure in the upper air bladder (3) and the lower air bladder in the outer contour skeleton of the wing is different. The pressure difference is used to make one side of the wing spars (1-2) bend and deform towards the low-pressure side. Precise control of the reverse angle: The control system electrically stimulates the secondary electrothermal layer, and the contraction of the elastomer in the elastomer electrothermal layer (2) generates inward contraction prestress, causing the wing beam (1-2) on one side to deform slightly outward.

9. An aircraft, characterized in that, Including the variable dihedral inflatable folding wing based on an electroresponsive shape memory polymer as described in any one of claims 1-7.

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