A seamless flap based on double-layer deformable honeycomb flexible skin

Abstract

The invention discloses a seamless flap based on a double-layer deformable honeycomb flexible skin, which belongs to the field of flexible structure design of variant aircraft. The seamless flap comprises a flap deformation section and a flap fixing section; the flap deformation section is the part of the flap that participates in the deformation of the flexible skin during the deflection process, and comprises a flexible skin sealing plate, a deflection shaft, a deflection control surface, and a wing rear mast; when the flap is deflected downward, the deflection control surface rotates counterclockwise, the flexible skin of the upper wing surface is stretched in-plane under tension, and the flexible skin of the lower wing surface is compressed in-plane under pressure; the invention adopts the seamless flap to meet the large-angle deflection of the flap, so that the connection between the flap and the wing is smoother and continuous, and has sufficient out-of-plane load-bearing capacity; the out-of-plane load-bearing capacity and deformation effect of the flexible skin can also be changed by adjusting the structural parameters of the flexible skin, and the designability is strong, the production is simple, and the process is easy to implement.

Description

Technical Field

[0001] The invention relates to the field of flexible structure design of variant aircraft, and in particular to a seamless flap based on a double-layer deformable honeycomb flexible skin. Background Art

[0002] The shape-shifting aircraft changes its structural shape in real time to adapt to complex flight environments and maintain optimal aerodynamic performance during flight over a wide speed range. The wing lift-enhancing device can also generate sufficient lift by changing the curvature at low speeds, reducing the liftoff and landing speeds during takeoff and landing, and effectively shortening the taxiing distance. The seamless flap is a lift-enhancing device. Compared with traditional lift-enhancing devices, the seamless flap can smoothly and continuously change the wing deflection angle, and has better performance in terms of dynamic performance. In order to prevent the airflow from penetrating from the lower wing surface to the upper wing surface, sealing plates are respectively provided on the upper and lower wing surfaces at the connection between the trailing edge of the wing and the flap. Traditional sealing plates are mostly two elastic plates, one end of which is connected to the trailing edge of the wing, and the other end is overlapped on the flap deflection rudder surface. When the flap is deflected, the sealing plate cannot undergo in-plane deformation, but undergoes a large out-of-plane elastic deformation with the deflection rudder surface. The structure is as follows: Figure 1 As shown in the figure. When the flap is deflected at a large angle, the traditional sealing plate often cannot bear such a large deformation. With the development of flexible skin, the traditional sealing plate is replaced with flexible skin to form a seamless flap. With the deflection of the flap, the in-plane stretching or compression occurs, which can meet the large-angle deflection of the flap and make the deformation smoother and continuous.

[0003] The present invention proposes a seamless flap based on a double-layer deformable honeycomb flexible skin, in which the traditional sealing plate is replaced by the flexible skin. When the flap is deflected, the flexible skin undergoes a large in-plane deformation, which meets the requirements of large-angle deflection of the flap, making the connection between the flap and the wing smoother and more continuous, and having sufficient out-of-plane load-bearing capacity. Summary of the invention

[0004] The present invention provides a seamless flap based on a double-layer deformable honeycomb flexible skin, which replaces the traditional sealing plate with a flexible skin to solve the problem that the traditional sealing plate cannot meet the large-angle deflection of the flap. The flexible skin undergoes a large in-plane deformation to meet the large-angle deflection of the flap, making the flap deflection smoother and more continuous, and having sufficient out-of-plane load-bearing capacity.

[0005] The present invention is achieved in that:

[0006] The present invention provides a seamless flap based on a double-layer deformable honeycomb flexible skin, which is composed of a flap deformation section and a flap fixing section. The flap deformation section is the part of the flap that participates in the deformation of the flexible skin during the deflection process, and is composed of a flexible skin sealing plate, a deflection axis, a deflection control surface, and a wing rear mast. The deflection axis is at the leading edge point O of the seamless flap, and the flap deflects around the deflection axis. The deflection control surface is composed of an arc part and a straight line part in the middle of the arc, connecting the upper and lower wing surfaces of the flap. The gap between the deflection control surface and the wing rear mast is connected by a flexible skin. One end of the flexible skin is fixed to the upper (lower) wing surface of the flap at point A (B) near the leading edge of the flap, and the other end is fixed to the upper (lower) surface of the wing rear mast at point C (D), which is divided into an upper wing surface flexible skin and a lower wing surface flexible skin, ensuring that the flap is connected to the wing trailing edge smoothly and continuously with good air tightness. The fixed section of the flap is the part that keeps the shape fixed during the deflection of the flap and does not participate in the deformation of the flexible skin.

[0007] The flexible skin of the present invention is a double-layer deformable honeycomb flexible skin with a length of L, a width of W, and a thickness of h, and includes a double-layer deformable honeycomb core, a flexible filling, and an elastic surface layer. The out-of-plane stiffness of the flexible skin is provided by the facade of the double-layer deformable honeycomb wallboard, and the in-plane telescopic deformation is provided by the double-layer deformable honeycomb. The double-layer deformable honeycomb structure is formed by replicating and expanding a jujube-shaped unit cell, and the jujube-shaped unit cell is composed of flexible units. There are bending plates at different levels on the flexible unit, and the bending plates at different levels are bent in different directions. The bending plates at the same level are divided into an upper bending plate and a lower bending plate, and the bending directions are opposite, and there is a connecting plate in the middle. There is a connecting plate on the flexible unit, which naturally connects the roots of the bending plates at different levels together, thereby realizing the natural connection of the deformable honeycomb structures at different levels. The length of the flexible unit is a+2b, and the width is h, wherein a is the length of the connecting plate, and b is the length of the upper and lower bending plates. The flexible unit has an initial bending shape, and the lateral distance between the end of the bending plate and the connecting plate is c / 2. The in-plane deformation of the double-layer deformable honeycomb is borne by the deformation of the curved plates at different levels on the flexible unit. The flexible unit forms a slit with a length of b (the slit length must be consistent with the length of the curved plate) and a width of d at h / 2 in the width direction, and cuts the curved plate to form two levels of curved plates, namely, the upper curved plate 7 at the upper end, the lower curved plate 8 at the upper end, the upper curved plate 9 at the lower end, and the lower curved plate 10 at the lower end; when the end is subjected to in-plane load, the upper curved plate at the upper end bends to the right, the upper curved plate at the lower end bends to the left, the upper curved plate at the upper end bends to the left, and the lower curved plate at the lower end bends to the right.

[0008] The connecting plates of the flexible units arranged longitudinally in the double-layer deformable honeycomb are on the same straight line. A whole plate containing n (a+2b) can be used to replace the n flexible units in the same longitudinal column. The plate is marked, punched, and cut in the longitudinal direction according to the arrangement of b, a, 2b, a, 2b, a, …, 2b, a, b. Then the initial shape is punched out. The rule is that the bending direction of the upper bending plate and the lower bending plate on the same layer of the longitudinal flexible plate are opposite. The bending direction of the upper bending plate in the odd-numbered column is first right and then left, and the bending direction of the lower bending plate is first left and then right. The bending direction of the upper bending plate in the even-numbered column is first left and then right, and the bending direction of the lower bending plate is first right and then left. The bending plates that need to be connected on the same layer of adjacent longitudinal flexible plates are welded. Finally, the pores of the deformable honeycomb are filled in the form of silicone foam, and the surface is covered with silicone panels to ensure good air tightness of the structure and smoothness of the skin surface.

[0009] When the flap is deflected downward, the deflection control surface rotates counterclockwise, the upper wing surface flexible skin is stretched in-plane under tension, and the lower wing surface flexible skin is compressed in-plane under pressure. The maximum deflection angle of the flap is ɑ (not exceeding 60°), the distance between the flap deflection center point O and the upper wing surface flexible skin fixed point point A is x, after deflection point A moves to point A', and the upper wing surface flexible skin stretch amount is U 1 =xɑ. The distance between the flap deflection center O and point B is x. Under the action of in-plane compression and plane rotation, point B moves to point B', and the compression amount of the lower wing surface flexible skin is U 2 =2xsin(ɑ / 2).

[0010] The deformation of the flexible skin during flap deflection mainly occurs in the width direction. The size of the deformable honeycomb pores is related to the length of the flexible unit a+2b and the initial distance c between the adjacent flexible unit connecting plates. The length of the flexible unit a+2b and the initial distance c between the adjacent flexible unit connecting plates are preliminarily determined. The size of the flexible skin limits the number of transverse and longitudinal flexible units. The number of transverse flexible units m and the number of longitudinal flexible units n are preliminarily determined.

[0011] The overall deformation of the flexible skin is borne by the deformation of the flexible unit bending plate. The small deformation assumption requires that the bending plate deformation u≤0.15b, and the bending plate length b is preliminarily determined. The out-of-plane load-bearing capacity of the flexible skin is related to the flexible unit thickness t, the flexible unit width h, the flexible unit length a+2b, the number of transverse flexible units m, and the number of longitudinal flexible units n. The parameters are adjusted to meet the out-of-plane load-bearing capacity. The deformation capacity of the bending plate is related to the bending plate length b, the flexible unit thickness t, and the flexible unit width h. Finally, the bending plate length b, the flexible unit thickness t, and the flexible unit width h are determined.

[0012] Further improvements are made in that the thickness of the flexible skin is thicker than that of ordinary flexible skin. In order to make the surface of the seamless flap smoother after the flexible skin is installed, recessed structures are made on the upper and lower surfaces of the deflection rudder surface, which are the contact parts between the deflection rudder surface and the flexible skin during the entire deflection process. The depth of the recess is the difference in thickness between the flexible skin and the ordinary skin, and the front end part of the recess should be gradually transitioned.

[0013] Further improvement, when the flexible skin is compressed to a large extent, due to the lack of shape support, out-of-plane convexity or concaveness will be generated. In order to make the flexible skin smoother when deflected, the flexible skin should be pre-stretched during installation.

[0014] The beneficial effects of the present invention are:

[0015] 1. The seamless flap can meet the large-angle deflection of the flap, making the connection between the flap and the wing smoother and more continuous, and having sufficient out-of-plane load-bearing capacity;

[0016] 2. The present invention changes the outer bearing capacity and deformation effect of the flexible skin surface by adjusting the structural parameters of the flexible skin, and has strong designability, simple production, and easy process implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the traditional sealing plate mentioned in the background part of the specification of the present invention;

[0018] Figure 2 It is a schematic diagram of the seamless flap structure based on the double-layer deformable honeycomb flexible skin of the present invention;

[0019] Figure 3 This is a schematic diagram of a double-layer deformable honeycomb structure of the present invention;

[0020] Figure 4 This is a schematic diagram of the flexible unit structure of the present invention;

[0021] Figure 5 This is a schematic diagram of the deflection rudder surface concave structure of the present invention;

[0022] Among them, 1-deflection axis, 2-deflection control surface, 3-wing rear mast, 4-upper wing surface flexible skin, 5-lower wing surface flexible skin, 6-seamless flap fixed section, 7-upper end upper layer curved plate, 8-upper end lower layer curved plate, 9-lower end upper layer curved plate, 10-lower end lower layer curved plate, 11-connecting plate, 12-cutting slit, 13-crack stop hole, 14-recessed structure. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail by enumerating examples below. It should be noted that the specific implementation described here is only used to explain the present invention and is not used to limit the present invention.

[0024] like Figure 2 As shown in (a), a seamless flap based on a double-layer deformable honeycomb flexible skin of the present invention is composed of a flap deformation section and a flap fixing section, and the thick solid line represents the flexible skin sealing plate. The flap deformation section is the part that participates in the deformation of the flexible skin during the deflection process of the flap, including a flexible skin sealing plate, a deflection axis 1, a deflection control surface 2, and a wing rear mast 3; the deflection axis 1 is at the leading edge point O of the seamless flap, and the flap deflects around the deflection axis 1; the deflection control surface 2 is located at the leading edge of the flap, and the wing rear mast 3 is located at the trailing edge of the wing; the deflection control surface 2 includes an arc portion and a straight line portion in the middle of the arc; the upper and lower wing surfaces of the flap are connected by the deflection control surface 2; the deflection control surface 2 and the wing rear mast 3 are located at the trailing edge of the wing; the deflection control surface 2 includes a circular arc portion and a straight line portion in the middle of the circular ... upper and lower wing surfaces of the flap are connected by the deflection control surface 2; the upper and lower wing surfaces of the flap are connected by the deflection control surface 2; the upper and lower wing surfaces of the flap are connected by the deflection control surface 2; the upper and lower wing surfaces of the flap are connected by the deflection control surface 2; the upper and lower wing surfaces of the flap are connected by the The gap between the masts 3 is connected by a flexible skin; one end of the flexible skin is fixed to the upper and lower wing surfaces of the flap at points A and B near the leading edge of the flap, and the other end is fixed to the upper and lower surfaces of the wing rear mast 3 at points C and D, and is divided into an upper wing surface flexible skin 4 and a lower wing surface flexible skin 5. The upper wing surface flexible skin 4 and the lower wing surface flexible skin 5 ensure that the connection between the flap and the trailing edge of the wing is smooth, continuous and airtight; the flap fixed section is the part that keeps the shape of the flap fixed during the deflection process and does not participate in the deformation of the flexible skin.

[0025] The upper wing surface flexible skin and the lower wing surface flexible skin of the present invention are double-layer deformable honeycomb flexible skins with a length of L, a width of W, and a thickness of h, and include a double-layer deformable honeycomb core, a flexible filling, and an elastic surface layer. The out-of-plane stiffness of the flexible skin is provided by the facade of the double-layer deformable honeycomb wallboard, and the in-plane expansion and contraction deformation is provided by the double-layer deformable honeycomb. The double-layer deformable honeycomb structure is as follows: Figure 3 The double-layer deformable honeycomb structure is formed by replicating and expanding the jujube-shaped unit cell, which is composed of flexible units. The flexible unit structure is shown in Figure 4 shown.

[0026] When the flap is deflected downward, the deflection rudder rotates counterclockwise, the upper wing surface flexible skin is stretched in-plane, and the lower wing surface flexible skin is compressed in-plane. The structure is as follows: Figure 2 (b) When the flap is deflected, the deformation of the flexible skin mainly occurs in the width direction.

[0027] The present invention is further described in detail below through data examples.

[0028] Take a typical wing section, with a flexible skin length of L = 240 mm, a flexible skin width of W = 240 mm, and a flexible skin thickness of h = 10 mm. The deformation mainly occurs in the width direction. The material elastic modulus E = 71.7 GPa, the maximum deflection angle of the flap ɑ = 50°, the flap deflection center point O is on the chord line of the seamless flap, and the distance from the wing rear mast is l = 80 mm. The distance between the flap deflection center point O and the fixed point A of the upper wing flexible skin is x = 50 mm. The deformable honeycomb pores are required to have a length not exceeding 50 mm and a width not exceeding 20 mm.

[0029] The flap is deflected 50°, and the upper wing flexible skin stretches U 1 =43.6mm, compression of the lower wing surface flexible skin U 2 =42.3mm.

[0030] When the flap is deflected, the deformation of the flexible skin mainly occurs in the width direction. According to the requirements of the deformable honeycomb pores, the length of the flexible unit a+2b=24mm and the initial distance between the adjacent flexible unit connecting plates c=8mm are preliminarily determined. According to the size limit of the flexible skin, the number of transverse flexible units m=30 and the number of longitudinal flexible units n=10 are preliminarily determined. The overall deformation of the flexible skin is borne by the deformation of the flexible unit bending plate. The deformation of a single bending plate of the upper wing flexible skin u 1 =0.727mm, deformation of a single bending plate of the lower wing flexible skin u 2 =0.705mm. The small deformation assumption requires that the bending plate deformation u≤0.15b, and the bending plate length b=9mm and the connecting plate length a=6mm are preliminarily determined. The parameters are adjusted to meet the external load-bearing capacity of the flexible skin surface, and the flexible unit thickness t=0.2mm and the flexible unit width h=10mm are determined. According to the deformation requirements of the bending plate, the bending plate length b=9mm, the flexible unit thickness t=0.2mm, and the flexible unit width h=10mm are finally determined.

[0031] To make the flexible skin, 30 flexible boards with a length of 240 mm, a width of 10 mm, and a thickness of 0.2 mm should be selected. Take the lower left corner of the flexible board as the origin, start from (5, 0), draw a 9 mm line upward, and then draw a 18 mm line upward every 6 mm, and the last line is 9 mm. Make a crack stop hole with a diameter of 1.0 mm at the end of the line. Use a molybdenum wire with a diameter of 0.2 mm to cut the flexible board, pass the molybdenum wire through the crack stop hole, and cut along the line to make a longitudinal flexible board. According to the initial distance c = 8 mm between the connecting plates of adjacent flexible units and the initial bending shape of the flexible unit, the longitudinal flexible board is stamped. Arrange the 30 longitudinal flexible boards along the thickness direction of the connecting board, and weld the curved boards that need to be connected on the same layer of adjacent longitudinal flexible boards. Finally, fill the pores of the deformable honeycomb in the form of silicone foam, and cover the surface with silicone panels to ensure good air tightness of the structure and smoothness of the skin surface.

[0032] The thickness of the flexible skin is thicker than that of the ordinary flexible skin. In order to make the surface of the seamless flap smoother after the flexible skin is installed, a concave structure 14 is made on the upper and lower surfaces of the deflection rudder surface. It is the contact part between the deflection rudder surface and the flexible skin during the whole deflection process. The depth of the concave structure is the thickness difference between the flexible skin and the ordinary skin. The front end of the concave structure should be gradually transitioned. The structure is as follows: Figure 5 shown.

[0033] Before installing the flexible skin, make an 8mm depression on the part of the deflection rudder surface that contacts the flexible skin during the entire deflection process, and the 5mm part at the front end of the depression should be gradually transitioned. When installing the flexible skin, pre-stretch the flexible skin 30mm for fixation.

[0034] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A seamless flap based on a double-layer deformable honeycomb flexible skin, It is characterized in that The seamless flap comprises a flap deformation section and a seam flap fixing section (6); The flap deformation section is the part of the flap that participates in the deformation of the flexible skin during the deflection process, and includes a flexible skin sealing plate, a deflection axis (1), a deflection control surface (2), and a wing rear mast (3); the deflection axis (1) is located at the leading edge point O of the seamless flap, and the flap deflects around the deflection axis (1); the deflection control surface (2) is located at the leading edge of the flap, and the wing rear mast (3) is located at the trailing edge of the wing; The deflection control surface (2) comprises an arc portion and a straight portion in the middle of the arc; the deflection control surface (2) connects the upper and lower wing surfaces of the flap; the gap between the deflection control surface (2) and the rear mast (3) of the wing is connected by a flexible skin; One end of the flexible skin is fixed to points A and B on the upper and lower wing surfaces of the flap near the leading edge of the flap, and the other end is fixed to points C and D on the upper and lower surfaces of the wing rear mast (3), and is divided into an upper wing surface flexible skin (4) and a lower wing surface flexible skin (5). The upper wing surface flexible skin (4) and the lower wing surface flexible skin (5) ensure that the flap is connected to the trailing edge of the wing smoothly and continuously with good air tightness; the flap fixed section is the part that keeps the shape of the flap fixed during the deflection process and does not participate in the deformation of the flexible skin; A flexible skin, which is a double-layer deformable honeycomb flexible skin with a length of L, a width of W, and a thickness of h; The invention comprises a double-layer deformable honeycomb core, a flexible filling and an elastic surface layer; the out-of-plane stiffness of the flexible skin is provided by the facade of the double-layer deformable honeycomb wall panel, and the in-plane expansion and contraction deformation is provided by the double-layer deformable honeycomb; the double-layer deformable honeycomb structure is formed by replicating and expanding a jujube-shaped unit cell, and the jujube-shaped unit cell is composed of flexible units; there are bending plates at different levels on the flexible unit, and the bending plates at different levels are bent in different directions. The bending plates at the same level are divided into upper bending plates and lower bending plates, and the bending directions are opposite, and there is a connecting plate (11) in the middle; there are connecting plates on the flexible unit, which naturally connect the roots of the bending plates at different levels together, thereby realizing the natural connection of the deformable honeycomb structures at different levels; the length of the flexible unit is a+2b and the width is h, wherein a is the length of the connecting plate, and b is the length of the upper and lower bending plates; the flexible unit has an initial bending shape, and the lateral distance between the end of the bending plate and the connecting plate is c / 2, and c is the initial distance between the connecting plates of adjacent flexible units; the in-plane deformation of the double-layer deformable honeycomb is borne by the deformation of the bending plates at different levels on the flexible unit.

2. A seamless flap based on a double-layer deformable honeycomb flexible skin according to claim 1, It is characterized in that When the flap is deflected downward, the deflection control surface rotates counterclockwise, the upper wing surface flexible skin (4) is stretched in-plane under tension, and the lower wing surface flexible skin (5) is compressed in-plane under pressure; the maximum deflection angle of the flap is ɑ, which does not exceed 60°, the distance between the flap deflection center point O and the fixed point A of the upper wing surface flexible skin (4) is x, and after deflection, point A moves to point A', and the stretching amount of the upper wing surface flexible skin (4) is U 1 = xɑ; the distance between the flap deflection center O and point B is x. Under the action of in-plane compression and plane rotation, point B moves to point B', and the compression amount of the lower wing surface flexible skin is U 2 =2xsin(ɑ / 2).

3. A seamless flap based on a double-layer deformable honeycomb flexible skin according to claim 1, It is characterized in that The flexible unit forms a slit of length b and width d at h / 2 in the width direction, cutting the bending plate to form two layers of bending plates, namely, an upper layer bending plate (7) at the upper end, a lower layer bending plate (8) at the upper end, an upper layer bending plate (9) at the lower end, and a lower layer bending plate (10) at the lower end; when the ends are subjected to in-plane loads, the upper layer bending plate at the upper end bends to the right and the lower layer bending plate at the lower end bends to the left, the upper layer bending plate at the upper end bends to the left, and the lower layer bending plate at the lower end bends to the right.

4. A seamless flap based on a double-layer deformable honeycomb flexible skin according to claim 1, It is characterized in that The connecting plates of the longitudinally arranged flexible units of the double-layer deformable honeycomb are on the same straight line. A whole plate containing n (a+2b) can be used to replace the n flexible units in the same longitudinal column. Lines are drawn, crack-stopping holes (13) are punched, and slits (12) are cut in the longitudinal direction of the plate in the arrangement mode of b, a, 2b, a, 2b, a, ..., 2b, a, b; then the initial shape is punched out, and the upper end bending plate and the lower end bending plate on the same layer of the longitudinal flexible plate have opposite bending directions. The bending directions of the upper bending plates in the odd-numbered columns are first right and then left, and the bending directions of the lower bending plates are first left and then right; the bending directions of the upper bending plates in the even-numbered columns are first left and then right, and the bending directions of the lower bending plates are first right and then left; the bending plates on the same layer of adjacent longitudinal flexible plates that need to be connected are welded; finally, the pores of the deformable honeycomb are filled in the form of silicone foam, and the surface is covered with silicone panels to ensure good air tightness of the structure and smoothness of the skin surface.

5. A seamless flap based on a double-layer deformable honeycomb flexible skin according to claim 4, It is characterized in that The deformation of the flexible skin occurs in the width direction when the flap is deflected; the size of the deformable honeycomb pores is related to the flexible unit length a+2b and the initial distance c of the adjacent flexible unit connecting plates, and the flexible unit length a+2b and the initial distance c of the adjacent flexible unit connecting plates are preliminarily determined; the flexible skin size limits the number of transverse and longitudinal flexible units, and the number of transverse flexible units m and the number of longitudinal flexible units n are preliminarily determined; the overall deformation of the flexible skin is borne by the deformation of the flexible unit bending plate, and the small deformation assumption requires that the bending plate deformation u≤0.15b, and the bending plate length b is preliminarily determined; the out-of-plane load-bearing capacity of the flexible skin is related to the flexible unit thickness t, the flexible unit width h, the flexible unit length a+2b, the transverse flexible unit number m, and the longitudinal flexible unit number n, and the parameters are adjusted to meet the out-of-plane load-bearing capacity; the deformation capacity of the bending plate is related to the bending plate length b, the flexible unit thickness t, and the flexible unit width h, and the bending plate length b, the flexible unit thickness t, and the flexible unit width h are finally determined.

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