Wing skin, wing, tilting rotorcraft and manufacturing method of wing skin

Abstract

The invention discloses a wing skin, a wing, a tilt rotorcraft and a manufacturing method of the wing skin, and relates to the technical field of wing vibration damping, the wing skin comprises a first panel, a second panel and a middle-layer plate, the middle-layer plate comprises a plurality of superlattice blocks, and each superlattice block comprises a first plate, a second plate, a cross rod, a first truss and a second truss; the first truss is provided with a first end, a second end, a third end and a fourth end, the first end and the second end are symmetrical about the plane of the cross rod, and the third end and the fourth end are symmetrical about the center line of the superlattice block; the second truss is provided with a fifth end, a sixth end, a seventh end and an eighth end, the fifth end and the sixth end are symmetrical about the plane of the cross rod, and the seventh end and the eighth end are symmetrical about the center line of the superlattice block; the first end and the fifth end are fixedly connected with the first plate, the second end and the sixth end are fixedly connected with the second plate, and the third end, the fourth end, the seventh end and the eighth end are fixedly connected with the cross rod; according to the invention, vibration can be effectively suppressed, and the weight can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of wing vibration reduction, and particularly to a wing skin, a wing, a tiltrotor aircraft, and a manufacturing method of the wing skin. Background Art

[0002] As a new type of aircraft, the tiltrotor aircraft combines the advantages of fixed-wing aircraft and helicopters and has great flexibility in the takeoff and landing mode. Especially in the vertical takeoff and landing mode, the tiltrotor aircraft can achieve vertical takeoff and landing like a helicopter and has a high-speed cruise ability similar to that of a fixed-wing aircraft when switching to the forward flight mode.

[0003] However, the system of the tiltrotor aircraft is a classic rigid-flexible coupling system. A large-mass nacelle equipped with a complex transmission mechanism and a rotor are jointly installed on the outermost side of the wing. Even a small disturbance will cause obvious elastic deformation of the wing, making the rigid-flexible coupling, inertial coupling, and aeroelastic coupling of the tiltrotor aircraft stronger than the rotor / airframe coupling of a helicopter. During the flight of the tiltrotor aircraft, especially during the conversion process and in the high-speed flight mode, due to the rotation of the rotor and the instability of the airflow, the wing may be affected by the rotational flutter caused by the low-frequency vibration of the coupling mode. These vibrations not only affect the flight stability but also limit the flight envelope and reduce the safety of the tiltrotor aircraft. Therefore, effective measures must be taken to suppress the rotational flutter caused by low-frequency vibration.

[0004] In the prior art, the measures for suppressing the rotational flutter of the wing of a tiltrotor aircraft usually include the following implementation schemes: by optimizing the geometric shape of the wing such as wingspan, airfoil design, etc., to improve the aerodynamic performance and reduce the vibration response. Usually, a complex wing profile design is required to reduce the aeroelastic instability caused by low-frequency vibration. However, this method has limited effect in solving low-frequency vibration and increases the design complexity of the wing; in some more advanced designs, active control technology is adopted. By real-time monitoring the wing vibration and adjusting the aileron of the wing to dynamically suppress the vibration, this method requires high-precision sensors and fast-response actuators. Although it can effectively suppress the vibration, the cost and the complexity of the mechanism design are relatively high. To sum up, the existing measures for suppressing the rotational flutter of the wing of a tiltrotor aircraft usually optimize the geometric shape of the wing or actively control the aileron of the wing to dynamically suppress the vibration, both of which increase the design complexity of the wing, increase the wing mass, reduce the effective payload, and are costly. Summary of the Invention

[0005] The purpose of the present invention is to provide a wing skin, a wing, a tiltrotor aircraft, and a manufacturing method of the wing skin to solve the problems existing in the above prior art, which can not only effectively suppress vibration but also reduce weight.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a wing skin, which includes a first panel, a second panel, and a middle layer panel. The middle layer panel includes a plurality of superlattice blocks, and the superlattice blocks are arranged in a flat and sequential manner. Each superlattice block includes a first plate, a second plate, a cross bar, at least one first truss, and at least one second truss. The first plate is fixedly connected to the first panel, the second plate is fixedly connected to the second panel, the cross bar is disposed on a cross bar plane in the middle of the first plate and the second plate, the cross bar plane, the first plate, and the second plate are parallel, the cross bar plane is perpendicular to the center line of the superlattice block, the first truss is disposed on a first truss plane, the second truss is disposed on a second truss plane, and the second truss plane intersects the first truss plane at the center line of the superlattice block; the first truss has a first end, a second end, a third end, and a fourth end, the first end and the second end are symmetric about the cross bar plane, the third end and the fourth end are symmetric about the center line of the superlattice block; the second truss has a fifth end, a sixth end, a seventh end, and an eighth end, the fifth end and the sixth end are symmetric about the cross bar plane, the seventh end and the eighth end are symmetric about the center line of the superlattice block; the first end and the fifth end are both fixedly connected to the first plate, the second end and the sixth end are both fixedly connected to the second plate, and the third end, the fourth end, the seventh end, and the eighth end are all fixedly connected to the cross bar.

[0008] Preferably, the first truss includes a first truss rod, a second truss rod, a third truss rod, and a fourth truss rod; the first truss rod and the second truss rod are disposed between the first plate and the cross bar plane, the first end of the first truss rod and the first end of the second truss rod are both fixedly connected to the first plate, the second end of the first truss rod and the second end of the second truss rod are both fixedly connected to the cross bar, and the first truss rod and the second truss rod are symmetric about the center line of the superlattice block; the third truss rod and the fourth truss rod are disposed between the second plate and the cross bar plane, the first end of the third truss rod and the first end of the fourth truss rod are both fixedly connected to the second plate, the second end of the third truss rod and the second end of the fourth truss rod are both fixedly connected to the cross bar, and the third truss rod and the fourth truss rod are symmetric about the center line of the superlattice block; the third truss rod and the first truss rod are symmetric about the cross bar plane.

[0009] Preferably, the second truss includes a fifth truss rod, a sixth truss rod, a seventh truss rod, and an eighth truss rod; the fifth truss rod and the sixth truss rod are disposed between the first plate and the cross-bar plane. The first ends of the fifth truss rod and the sixth truss rod are both fixedly connected to the first plate, and the second ends of the fifth truss rod and the sixth truss rod are both fixedly connected to the cross-bar. The fifth truss rod and the sixth truss rod are symmetric about the center line of the superlattice block; the seventh truss rod and the eighth truss rod are disposed between the second plate and the cross-bar plane. The first ends of the seventh truss rod and the eighth truss rod are both fixedly connected to the second plate, and the second ends of the seventh truss rod and the eighth truss rod are both fixedly connected to the cross-bar. The seventh truss rod and the eighth truss rod are symmetric about the center line of the superlattice block; the seventh truss rod and the fifth truss rod are symmetric about the cross-bar plane.

[0010] Preferably, the first truss rod, the second truss rod, the third truss rod, and the fourth truss rod are all first curved rods, and the first curved rods are recessed in the direction close to the cross-bar; the fifth truss rod, the sixth truss rod, the seventh truss rod, and the eighth truss rod are all second curved rods, and the second curved rods are convex in the direction away from the cross-bar.

[0011] Preferably, the expression of the center line of the first curved rod is:

[0012]

[0013] where C1(u) is the point of the center line of the first curved rod at parameter u, P i is the control point, and P0 is the end point of the first end of the first curved rod, P3 is the end point of the second end of the first curved rod, P1 and P2 are two points between the end point of the first end of the first curved rod and the end point of the second end of the first curved rod, w i is the weight corresponding to the control point, N i,p (u) is the basis function, where p is the degree of the curve, p takes 3, u is the parameter within the knot vector range, u ∈ [0, 1], and i takes 0, 1, 2, or 3;

[0014] The expression of the center line of the second curved rod is:

[0015]

[0016] where C2(u) is the point of the center line of the second curved rod at parameter u, P iis a control point, P4 is the endpoint of the first end of the second bending rod, P7 is the endpoint of the second end of the second bending rod, P5 and P6 are two points between the endpoint of the first end of the second bending rod and the endpoint of the second end of the second bending rod, w i is the weight corresponding to the control point, N i,p (u) is a basis function, where p is the degree of the curve, p takes 3, u is the parameter within the knot vector, u ∈ [0, 1], and i takes 4, 5, 6, or 7.

[0017] Preferably, the number of the first truss is one, the number of the second truss is one, the plane of the second truss is perpendicular to the plane of the first truss; the shape of the superlattice block is a cube; the first panel, the second panel, and the middle layer board are all glass fiber reinforced nylon 1010 boards.

[0018] Preferably, the superlattice block further includes at least three support rods, each of the support rods is arranged around the center line of the superlattice block, one end of each support rod is fixedly connected to the first board, and the other end of each support rod is fixedly connected to the second board.

[0019] The present invention also provides a wing, including the wing skin as described above.

[0020] The present invention also provides a tilt-rotor aircraft, including the wing as described above.

[0021] The present invention also provides a manufacturing method for a wing skin, used for manufacturing the wing skin as described above, including the following steps:

[0022] Step 1: Design and document preparation, use computer-aided design software to design the three-dimensional model of the middle layer board, and convert the model into the format for SLS printing through slicing software to generate the printing path for each layer;

[0023] Step 2: Select powder materials;

[0024] Step 3: Conduct powder laying and temperature control and setting, set the temperatures of the cavity, the printing platform, and the nozzle according to the selected powder materials;

[0025] Step 4: Conduct laser sintering, the laser passes through a computer-controlled scanning system, sinter the powder materials layer by layer according to the predetermined path, the powder particles are melted and fused, after each layer of printing is completed, the laser stops working and waits to cool to normal temperature to form a solid layer; sinter and cool and solidify layer by layer until the cooling and solidification of the last layer are completed, and finally construct the three-dimensional model, and the printing of the middle layer board ends;

[0026] Step 5: Fix and cover the first panel and the second panel on both sides of the middle layer board to obtain the wing skin.

[0027] The present invention has achieved the following technical effects compared with the prior art:

[0028] The wing skin, wing, tiltrotor aircraft and manufacturing method of the wing skin provided by the present invention are provided with a first panel and a second panel, which are enclosed to form the surface of the skin. A middle layer plate is arranged between the first panel and the second panel. The middle layer plate is divided into several superlattice blocks arranged in a flat and sequential manner. In each superlattice block, the cross-bar plane, the first plate and the second plate are parallel, the cross-bar plane is perpendicular to the center line of the superlattice block. The first truss is placed on the first truss plane, the second truss is placed on the second truss plane, the second truss plane intersects the first truss plane at the center line of the superlattice block. The first end and the fifth end are both fixedly connected to the first plate, the second end and the sixth end are both fixedly connected to the second plate, the third end, the fourth end, the seventh end and the eighth end are all fixedly connected to the cross-bar. The first end and the second end are symmetric about the cross-bar plane, the third end and the fourth end are symmetric about the center line of the superlattice block, the fifth end and the sixth end are symmetric about the cross-bar plane, and the seventh end and the eighth end are symmetric about the center line of the superlattice block. Based on the superstructural bandgap theory, the structure formed by the first truss, the second truss and the cross-bar can be equivalent to an inertial amplification superstructure composed of mass-spring-linkages, having an inertial amplification effect. The inertial amplification effect makes the dynamic equivalent mass of the structure greater than the actual mass, with a better low-frequency vibration suppression effect, which helps to disperse the propagation of vibration, and strengthen the stiffness and stability of the area. It can achieve high strength and stiffness under a relatively light structural weight, achieve significant suppression of low-frequency vibration, and maintain the load-bearing capacity of the structure, providing new ideas and methods for the application of metamaterial structures in the aviation field. At the same time, it provides a practical solution for engineering applications, demonstrating the great potential of lightweight materials in the field of vibration control. The lightweight superlattice blocks can meet the requirements of high strength, high stiffness and good vibration damping effect by laying only one layer, which can effectively suppress the low-frequency vibration and rotational flutter of the wing, achieve the effect of lightweight low-frequency vibration damping, while reducing the weight of the wing, improving the effective payload, maintaining the best load-bearing performance, improving fuel efficiency, optimizing aerodynamic characteristics, expanding the flight envelope of the tiltrotor aircraft, enhancing flight safety and stability, improving the efficiency and performance of the tiltrotor aircraft. At the same time, it also reduces the thickness of the wing skin and does not require the installation of additional mechanisms. The wing skin provided in this embodiment reduces the early wing shape design cost compared with the existing measures of optimizing the wing geometry or actively controlling the ailerons of the wing to suppress the rotational flutter of the tiltrotor aircraft, and there is no need for complex drive mechanisms and feedback mechanisms inside the wing. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 Schematic diagram of the wing skin provided by the present invention;

[0031] Figure 2 For Figure 1 Schematic diagram of the superlattice block in

[0032] Figure 3 For Figure 2 Schematic diagram of the first truss in the superlattice block in

[0033] Figure 4 For Figure 2 Schematic diagram of the second truss in the superlattice block in

[0034] Figure 5 For Figure 2 Schematic diagram of the cross bar in the superlattice block in

[0035] Figure 6 For Figure 2 Schematic diagram of the combination of the first truss and the second truss in the superlattice block in

[0036] Figure 7 For Figure 2 An equivalent diagram of the superlattice block in

[0037] Figure 8 Schematic diagram of the installation of the wing skin provided by the present invention;

[0038] Figure 9 Schematic diagram of the manufacturing method of the wing skin provided by the present invention;

[0039] Figure 10 Diagram of the aerodynamic elastic stability calculation results of the full-scale Bell tiltrotor aircraft publicly disclosed by NASA;

[0040] In the figure: 1 - first panel, 2 - second panel, 3 - middle layer board, 4 - first board, 5 - second board, 6 - cross bar, 7 - first truss rod, 8 - second truss rod, 9 - third truss rod, 10 - fourth truss rod, 11 - fifth truss rod, 12 - sixth truss rod, 13 - seventh truss rod, 14 - eighth truss rod, 15 - support rod. Detailed implementation manners

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] The object of the present invention is to provide a wing skin, a wing, a tilt-rotor aircraft, and a manufacturing method of the wing skin, so as to solve the problems existing in the above-mentioned prior art, which can effectively suppress vibration and reduce weight.

[0043] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Embodiment 1

[0045] As Figures 1 to 8 shown, this embodiment provides a wing skin, which includes a first panel 1, a second panel 2, and a middle layer panel 3. The middle layer panel 3 includes a plurality of superlattice blocks, and the superlattice blocks are arranged in a flat pattern in sequence. Each superlattice block includes a first plate 4, a second plate 5, a cross bar 6, at least one first truss, and at least one second truss. The first plate 4 is fixedly connected to the first panel 1, the second plate 5 is fixedly connected to the second panel 2, the cross bar 6 is placed on the cross bar plane in the middle of the first plate 4 and the second plate 5. The cross bar plane, the first plate 4, and the second plate 5 are parallel, and the cross bar plane is perpendicular to the center line of the superlattice block. The first truss is placed on the first truss plane, the second truss is placed on the second truss plane, and the second truss plane intersects the first truss plane at the center line of the superlattice block. The first truss has a first end, a second end, a third end, and a fourth end. The first end and the second end are symmetric about the cross bar plane, and the third end and the fourth end are symmetric about the center line of the superlattice block. The second truss has a fifth end, a sixth end, a seventh end, and an eighth end. The fifth end and the sixth end are symmetric about the cross bar plane, and the seventh end and the eighth end are symmetric about the center line of the superlattice block. The first end and the fifth end are both fixedly connected to the first plate 4, the second end and the sixth end are both fixedly connected to the second plate 5, and the third end, the fourth end, the seventh end, and the eighth end are all fixedly connected to the cross bar 6.

[0046] As Figure 10 shown, this figure is the aerodynamic elastic stability calculation result of the full-scale Bell tilt-rotor aircraft publicly disclosed by NASA. q1 and q2 are the low-order modes of the wing. As the forward flight speed increases, the damping ratio of this mode decreases rapidly, the system gradually becomes unstable, and enters the rotary flutter state; at Figure 10Among them, q1, q2, and p represent the wing's fundamental vertical bending mode, chordwise bending mode, and torsional mode respectively; β and β + 1 represent the rotor flapping collective and advancing modes respectively; ζ + 1 and ζ - 1 represent the rotor lag advancing and retreating modes respectively.

[0047] The wing skin provided by the present embodiment is provided with a first panel 1 and a second panel 2, which serve as the surface of the skin after being closed; a middle plate 3 is provided between the first panel 1 and the second panel 2; the middle plate 3 is divided into a plurality of superlattice blocks arranged in sequence; in each superlattice block, the cross bar plane, the first plate 4 and the second plate 5 are parallel; the cross bar plane is perpendicular to the center line of the superlattice block; the first truss is placed on the first truss plane; the second truss is placed on the second truss plane; the second truss plane intersects with the first truss plane at the center line of the superlattice block; the first end and the fifth end are both fixedly connected to the first plate 4; the second end and the sixth end are both fixedly connected to the second plate 5; the third end, the fourth end, the seventh end and the eighth end are all fixedly connected to the cross bar 6; the first end and the second end are symmetrical about the cross bar plane; the third end and the fourth end are symmetrical about the center line of the superlattice block; the fifth end and the sixth end are symmetrical about the cross bar plane; the seventh end and the eighth end are symmetrical about the center line of the superlattice block; based on the superstructure bandgap theory (Superstructure Bandgap Theory (Superstructure Bandgap Theory (Superstructure Bandgap Theory (Superstructure Bandgap Theory (Superstructure Bandgap Theory (Superstructure Bandgap Theory ( The theory is a theory that studies the propagation characteristics of waves (elastic waves, electromagnetic waves, sound waves, etc.) in periodic superstructures (such as phononic crystals, photonic crystals, elastic metamaterials, etc.). The core lies in explaining and designing band gaps, that is, the forbidden band phenomenon in which waves cannot propagate within a specific frequency range. In this embodiment, a suitable band gap is designed through a periodic superstructure to suppress the propagation of low-frequency vibrations). The structure formed by the first truss, the second truss and the cross rod 6 can be equivalent to an inertial amplification superstructure composed of mass-spring-connecting rod, which has an inertial amplification effect. The inertial amplification effect makes the dynamic equivalent mass of the structure greater than the actual mass, which has a better effect on suppressing low-frequency vibrations, helps to disperse the propagation of vibrations, and strengthens the stiffness and stability of the region. It can achieve higher strength and stiffness at a relatively light structural weight, achieve significant suppression of low-frequency vibrations, and maintain the bearing capacity of the structure, which is a good example for the application of metamaterial structures in the aviation field. The application provides new ideas and methods, and at the same time provides practical solutions for engineering applications, demonstrating the great potential of lightweight materials in the field of vibration control. Only one layer of lightweight superlattice blocks can meet the requirements of high strength, high stiffness and good vibration reduction, and can effectively suppress low-frequency vibration and rotation flutter of the wing, and achieve the effect of lightweight low-frequency vibration reduction. At the same time, it reduces the weight of the wing, increases the effective load, maintains the best load-bearing performance, improves fuel efficiency, optimizes aerodynamic characteristics, expands the flight envelope of the tiltrotor aircraft, enhances flight safety and stability, and improves the efficiency and performance of the tiltrotor aircraft. At the same time, it also reduces the thickness of the wing skin, and no additional mechanism needs to be installed. Compared with the existing measures for optimizing the geometry of the wing or actively controlling the aileron of the wing to suppress the rotation flutter of the tiltrotor aircraft, the wing skin provided in this embodiment reduces the cost of the early wing shape design, and no complex drive mechanism and feedback mechanism are required inside the wing.

[0048] As a relatively preferred implementation manner of this embodiment, the first truss includes a first truss rod 7, a second truss rod 8, a third truss rod 9, and a fourth truss rod 10; the first truss rod 7 and the second truss rod 8 are disposed between the first plate 4 and the cross-bar plane. The first ends of the first truss rod 7 and the second truss rod 8 are both fixedly connected to the first plate 4, and the second ends of the first truss rod 7 and the second truss rod 8 are both fixedly connected to the cross-bar 6. The first truss rod 7 and the second truss rod 8 are symmetric about the center line of the superlattice block; the third truss rod 9 and the fourth truss rod 10 are disposed between the second plate 5 and the cross-bar plane. The first ends of the third truss rod 9 and the fourth truss rod 10 are both fixedly connected to the second plate 5, and the second ends of the third truss rod 9 and the fourth truss rod 10 are both fixedly connected to the cross-bar 6. The third truss rod 9 and the fourth truss rod 10 are symmetric about the center line of the superlattice block; the third truss rod 9 and the first truss rod 7 are symmetric about the cross-bar plane, and the fourth truss rod 10 and the second truss rod 8 are symmetric about the cross-bar plane. The first ends of the first truss rod 7 and the second truss rod 8 form the first end of the first truss, the first ends of the third truss rod 9 and the fourth truss rod 10 form the second end of the first truss, the second ends of the first truss rod 7 and the third truss rod 9 form the third end of the first truss, and the second ends of the second truss rod 8 and the fourth truss rod 10 form the fourth end of the first truss. The structure is simple and convenient for manufacturing and use.

[0049] As a relatively preferred embodiment of this embodiment, the second truss includes a fifth truss rod 11, a sixth truss rod 12, a seventh truss rod 13, and an eighth truss rod 14; the fifth truss rod 11 and the sixth truss rod 12 are disposed between the first plate 4 and the cross-bar plane. The first ends of the fifth truss rod 11 and the sixth truss rod 12 are both fixedly connected to the first plate 4, and the second ends of the fifth truss rod 11 and the sixth truss rod 12 are both fixedly connected to the cross-bar 6. The fifth truss rod 11 and the sixth truss rod 12 are symmetric about the center line of the superlattice block; the seventh truss rod 13 and the eighth truss rod 14 are disposed between the second plate 5 and the cross-bar plane. The first ends of the seventh truss rod 13 and the eighth truss rod 14 are both fixedly connected to the second plate 5, and the second ends of the seventh truss rod 13 and the eighth truss rod 14 are both fixedly connected to the cross-bar 6. The seventh truss rod 13 and the eighth truss rod 14 are symmetric about the center line of the superlattice block; the seventh truss rod 13 and the fifth truss rod 11 are symmetric about the cross-bar plane, and the eighth truss rod 14 and the sixth truss rod 12 are symmetric about the cross-bar plane. The first ends of the fifth truss rod 11 and the sixth truss rod 12 form the first end of the second truss, the first ends of the seventh truss rod 13 and the eighth truss rod 14 form the second end of the second truss, the second ends of the fifth truss rod 11 and the seventh truss rod 13 form the third end of the second truss, and the second ends of the sixth truss rod 12 and the eighth truss rod 14 form the fourth end of the second truss. The structure is simple and convenient for manufacturing and use.

[0050] As a relatively preferred embodiment of this embodiment, the first truss rod 7, the second truss rod 8, the third truss rod 9, and the fourth truss rod 10 are all first curved rods. The first curved rods are recessed in the direction close to the cross-bar 6, increasing the sectional moment of inertia, improving the flexural rigidity, delaying buckling failure. The arch structure uses geometric stiffness to disperse the load, increasing the self-stability, and can significantly improve the mechanical properties, lightweight level, and functional adaptability of the structure; the fifth truss rod 11, the sixth truss rod 12, the seventh truss rod 13, and the eighth truss rod 14 are all second curved rods. The second curved rods protrude in the direction away from the cross-bar 6, facilitating the absorption of energy through elastic deformation. The arch structure uses geometric stiffness to disperse the load, increasing the self-stability, and can significantly improve the mechanical properties, lightweight level, and functional adaptability of the structure, and can significantly suppress low-frequency vibration and maintain the load-bearing capacity of the structure.

[0051] As a relatively preferred embodiment of this embodiment, the expression of the center line of the first curved rod is:

[0052]

[0053] where C1(u) is the point on the center line of the first curved rod at parameter u, P iis a control point, P0 is the endpoint of the first end of the first curved rod, P3 is the endpoint of the second end of the first curved rod, P1 and P2 are two points between the endpoint of the first end of the first curved rod and the endpoint of the second end of the first curved rod, w i is the weight corresponding to the control point, N i,p (u) is the basis function, where p is the degree of the curve, p takes 3, u is the parameter within the knot vector range, u ∈ [0, 1], and i takes 0, 1, 2, or 3;

[0054] The expression of the centerline of the second curved rod is:

[0055]

[0056] where C2(u) is the point of the centerline of the second curved rod at the parameter u, P i is a control point, and P4 is the endpoint of the first end of the second curved rod, P7 is the endpoint of the second end of the second curved rod, P5 and P6 are two points between the endpoint of the first end of the second curved rod and the endpoint of the second end of the second curved rod, w i is the weight corresponding to the control point, N i,p (u) is the basis function, where p is the degree of the curve, p takes 3, u is the parameter within the knot vector range, u ∈ [0, 1], and i takes 4, 5, 6, or 7.

[0057] The expressions of the centerlines of the first curved rod and the second curved rod are both designed based on the principle of NURBS (Non-Uniform Rational B-Splines, NURBS, non-uniform rational B-spline curves). NURBS curves have the advantage of curvature continuity, eliminating the curvature mutation of traditional broken lines or Bezier curves, thereby reducing microcracks caused by vibration and extending the service life of the rod under aerodynamic and structural alternating loads. NURBS curves can be adjusted by local control points or knot vectors to specifically strengthen high-stress areas (such as rod joints, etc.), avoiding global material waste and solving the stress concentration problem of traditional designs. Compared with traditional straight rod designs, NURBS rod designs can reduce the mass of the rod while extending the fatigue life. The expression of the NURBS curve is:

[0058]

[0059] where C(t) is the point of the curve at the parameter t, P i is a control point, w i is the weight corresponding to the control point, N i,p (t) is the basis function, p is the degree of the curve, t is the parameter within the knot vector range, and the value is [0, 1].

[0060] As a more preferred embodiment of this embodiment, the number of the first trusses is one, the number of the second trusses is one, the plane of the second truss is perpendicular to the plane of the first truss. The first truss rod 7, the second truss rod 8, the fifth truss rod 11 and the sixth truss rod 12 are equivalently transformed into an inertial amplification "X"-type superstructure composed of four masses - four springs - four connecting rods. The third truss rod 9, the fourth truss rod 10, the seventh truss rod 13 and the eighth truss rod 14 are also equivalently transformed into an inertial amplification "X"-type superstructure composed of four masses - four springs - four connecting rods. The bandgap range is increased, the suppression range is wider, and the effect of suppressing low-frequency vibration is better. The cross-sections of the first truss rod 7, the second truss rod 8, the third truss rod 9, the fourth truss rod 10, the fifth truss rod 11, the sixth truss rod 12, the seventh truss rod 13 and the eighth truss rod 14 are preferably circular, and the radius is preferably 0.25 mm. Looking from the direction of the first plate 4, the first truss rod 7, the second truss rod 8, the fifth truss rod 11 and the sixth truss rod 12 are sequentially arranged in a circumferential array at 0°, 90°, 180° and 270°. The outer shape of the superlattice block is a cube, and the structural stability is relatively strong. In this embodiment, the length, width and height of the superlattice block are all 5.0 mm, and the thicknesses of the first plate 4 and the second plate 5 are both 0.25 mm. The first panel 1, the second panel 2 and the middle layer plate 3 are all glass fiber reinforced nylon 1010 plates. The glass fiber reinforced nylon 1010 plate is a plastic obtained by using nylon 1010 resin as the base material, glass fiber as the reinforcing material, adding processing aids, and melting, shearing, mixing and kneading or coating through an extruder. The glass fiber plays a reinforcing role in this material, providing high strength and high rigidity characteristics, while the polymer matrix provides corrosion resistance, impact resistance and good processability. The first panel 1, the second panel 2 and the middle layer plate 3 are all glass fiber reinforced nylon 1010 plates, which have obvious advantages in reducing the overall structural weight. For wings with high requirements for tensile strength and bending resistance, the reinforcing effect of glass fiber enables it to perform well under loads such as tension, compression and impact. In addition, the cost of the material itself is lower, and the processing process is relatively simple.

[0061] As a more preferred embodiment of this embodiment, the superlattice block further includes at least three support rods 15. Each support rod 15 is arranged around the center line of the superlattice block. One end of each support rod 15 is fixedly connected to the first plate 4, and the other end of each support rod 15 is fixedly connected to the second plate 5, which can effectively improve the structural stability. In this embodiment, the number of the support rods 15 is four. The outer shape of the superlattice block is a cube, and the first plate 4 and the second plate 5 are both square plates. The four support rods 15 are supported at the four corner vertices of the first plate 4 and the second plate 5. The cross-section of the support rod 15 is square, and the side length of the cross-section is 0.5 mm, which is convenient for fitting with the support rods 15 in adjacent superlattice blocks.

[0062] Embodiment Two

[0063] This embodiment provides a wing, including the wing skin in embodiment one.

[0064] The wing provided by the present embodiment is provided with a first panel 1 and a second panel 2, which serve as the surface of the skin after being closed, and a middle panel 3 is provided between the first panel 1 and the second panel 2, and the middle panel 3 is divided into a plurality of superlattice blocks which are arranged in sequence. In each superlattice block, the cross rod plane, the first plate 4 and the second plate 5 are parallel, the cross rod plane is perpendicular to the center line of the superlattice block, the first truss is placed on the first truss plane, the second truss is placed on the second truss plane, the second truss plane intersects with the first truss plane at the center line of the superlattice block, the first end and the fifth end are fixedly connected to the first plate 4, and the second end and the first truss plane are fixedly connected to the first plate 4. The six ends are all fixedly connected to the second plate 5, the third end, the fourth end, the seventh end and the eighth end are all fixedly connected to the cross rod 6, the first end and the second end are symmetrical about the plane of the cross rod, the third end and the fourth end are symmetrical about the center line of the superlattice block, the fifth end and the sixth end are symmetrical about the plane of the cross rod, and the seventh end and the eighth end are symmetrical about the center line of the superlattice block. Based on the superstructure band gap theory, the structure formed by the first truss, the second truss and the cross rod 6 can be equivalent to an inertia-amplifying superstructure composed of mass-spring-connecting rod, which has an inertia-amplifying effect. The inertia-amplifying effect makes the dynamic equivalent mass of the structure greater than the actual mass. The low-frequency vibration suppression effect is better, which helps to disperse the propagation of vibration and enhance the stiffness and stability of the area. It can achieve higher strength and stiffness at a relatively light structural weight, significantly suppress low-frequency vibration, and maintain the load-bearing capacity of the structure. It provides new ideas and methods for the application of metamaterial structures in the aviation field, and provides practical solutions for engineering applications, demonstrating the great potential of lightweight materials in the field of vibration control. Only one layer of lightweight superlattice blocks can meet the requirements of high strength, high stiffness and good vibration reduction effect, which can effectively suppress the low-frequency vibration and rotational flutter of the wing and achieve lightweight. The effect of low-frequency vibration reduction is achieved, while reducing the weight of the wing, increasing the effective load, maintaining the best load-bearing performance, improving fuel efficiency, optimizing aerodynamic characteristics, expanding the flight envelope of the tiltrotor aircraft, enhancing flight safety and stability, and improving the efficiency and performance of the tiltrotor aircraft. At the same time, the thickness of the wing skin is also reduced, and there is no need to install additional mechanisms. Compared with the existing measures of optimizing the geometry of the wing or actively controlling the ailerons of the wing to suppress the rotational flutter of the tiltrotor aircraft, the wing skin provided in this embodiment reduces the cost of the early wing shape design, and there is no need for complex drive mechanisms and feedback mechanisms inside the wing.

[0065] Embodiment 3

[0066] This embodiment provides a tiltrotor aircraft, including the wing in the second embodiment.

[0067] The tiltrotor aircraft provided in this embodiment is provided with a first panel 1 and a second panel 2, which are closed to form the surface of the skin. A middle layer plate 3 is arranged between the first panel 1 and the second panel 2. The middle layer plate 3 is divided into several superlattice blocks arranged in a flat and sequential manner. In each superlattice block, the cross-bar plane, the first plate 4 and the second plate 5 are parallel, the cross-bar plane is perpendicular to the center line of the superlattice block. The first truss is placed on the first truss plane, and the second truss is placed on the second truss plane. The second truss plane intersects the first truss plane at the center line of the superlattice block. The first end and the fifth end are both fixedly connected to the first plate 4, the second end and the sixth end are both fixedly connected to the second plate 5, the third end, the fourth end, the seventh end and the eighth end are all fixedly connected to the cross-bar 6. The first end and the second end are symmetric about the cross-bar plane, the third end and the fourth end are symmetric about the center line of the superlattice block, the fifth end and the sixth end are symmetric about the cross-bar plane, and the seventh end and the eighth end are symmetric about the center line of the superlattice block. Based on the superstructure bandgap theory, the structure formed by the first truss, the second truss and the cross-bar 6 can be equivalent to an inertial amplification superstructure composed of mass-spring-linkages, which has an inertial amplification effect. The inertial amplification effect makes the dynamic equivalent mass of the structure greater than the actual mass, has a better effect on suppressing low-frequency vibration, helps to disperse the propagation of vibration, and strengthens the stiffness and stability of the area. It can achieve high strength and stiffness under a relatively light structural weight, significantly suppress low-frequency vibration, and maintain the bearing capacity of the structure. It provides new ideas and methods for the application of metamaterial structures in the aviation field, and at the same time provides practical solutions for engineering applications, demonstrating the great potential of lightweight materials in the field of vibration control. The lightweight superlattice blocks can meet the requirements of high strength, high stiffness and good vibration damping effect by laying only one layer. It can effectively suppress the low-frequency vibration of the wing and the whirl flutter, achieve the effect of lightweight low-frequency vibration damping, reduce the weight of the wing at the same time, improve the effective load, maintain the best bearing performance, improve the fuel efficiency, optimize the aerodynamic characteristics, expand the flight envelope of the tiltrotor aircraft, enhance the flight safety and stability, improve the efficiency and performance of the tiltrotor aircraft, and at the same time reduce the thickness of the wing skin without the need to install additional mechanisms; compared with the existing measures of optimizing the geometric shape of the wing or actively controlling the aileron of the wing to suppress the whirl flutter of the tiltrotor aircraft, the wing skin provided in this embodiment reduces the cost of the preliminary wing shape design, and there is no need for complex drive mechanisms and feedback mechanisms inside the wing.

[0068] Embodiment 4

[0069] As Figure 9 shown, this embodiment provides a manufacturing method for a wing skin, which is used to manufacture the wing skin in Embodiment 1, and includes the following steps:

[0070] Step 1: Design and document preparation. Use computer-aided design software to design the three-dimensional model of the middle layer plate 3, and convert the model into the format for SLS printing through slicing software to generate the printing path for each layer.

[0071] Step 2: Select powder material;

[0072] Step 3: Conduct powder laying, temperature control and setting, and set the temperatures of the cavity, printing platform and nozzle according to the selected powder material;

[0073] Step 4: Conduct laser sintering. The laser passes through a computer-controlled scanning system and sinters the powder material layer by layer along a predetermined path. The powder particles are melted and fused. After each layer of printing is completed, the laser stops working and waits to cool to room temperature to form a solid layer. Sinter and cool layer by layer until the cooling and curing of the last layer are completed, and finally a three-dimensional model is constructed, and the printing of the middle layer plate 3 ends;

[0074] Step 5: Fix and cover the first panel 1 and the second panel 2 on both sides of the middle layer plate 3 to obtain the wing skin.

[0075] This embodiment provides a method for manufacturing a wing skin. The wing skin is manufactured by selective laser sintering 3D printing technology. The material selection range is wider, and it is more suitable for applications in the aviation field of functional prototypes, low-density structures and flexible materials. The cost of raw materials is lower, the utilization rate of materials is higher, and the characteristic of no need for a support structure makes the components printed by SLS more simplified and reduces the complexity of post-processing; in Step 5, the connection between the first panel 1 and the second panel 2 and the middle layer plate 3 can but is not limited to being bonded with an adhesive. As a relatively preferred implementation manner of this embodiment, the adhesive is an epoxy resin-based (Cytec FM series), and the adhesive is prefabricated into a film shape (thickness 0.2 mm) and cured at a high temperature (150 °C) during use.

[0076] As another relatively preferred implementation manner of this embodiment, this embodiment provides a method for manufacturing a wing skin. In Step 1, a three-dimensional model of the entire wing skin is directly designed using computer-aided design software, and the middle layer plate 3, the first panel 1 and the second panel 2 are integrally printed and formed, which can improve the structural stability.

[0077] As a relatively preferred implementation manner of this embodiment, short fiber type glass fiber reinforced nylon GF30PA1010 is selected, and the printed middle layer plate 3 has high precision, mechanical strength, heat resistance and corrosion resistance. The specific steps are as follows:

[0078] Step 1: Design and file preparation, use computer-aided design software CATIA to design a three-dimensional model of the middle layer plate 3, and convert the model into the G-code format for SLS printing through slicing software Materialise Magics to generate the printing path of each layer;

[0079] Step 2: Select the powder material as glass fiber reinforced nylon 1010 composite powder;

[0080] Step 3: Conduct powder laying, temperature control and setting. Set the temperatures of the cavity, printing platform and nozzle according to the selected powder material. The cavity temperature is set in the range of 170°C - 180°C, the temperature of the printing platform is maintained at 80°C - 90°C, and the nozzle temperature is set near the melting point of the powder material, which is 220°C - 240°C;

[0081] Step 4: Conduct laser sintering. The laser passes through a computer-controlled scanning system and sinters the powder material layer by layer along a predetermined path. The powder particles are melted and fused. After each layer of printing is completed, the laser stops working and waits to cool to room temperature to form a solid layer. Sinter layer by layer and cool and solidify until the last layer is cooled and solidified, finally constructing a three-dimensional model, and the printing of the middle panel 3 is completed;

[0082] Step 5: Fix and cover the first panel 1 and the second panel 2 on both sides of the middle panel 3 to obtain the wing skin.

[0083] In Step 1, during the slicing process, specifically for generating the printing path of each layer;

[0084] In Step 2, the glass fiber reinforced nylon 1010 composite powder is a short fiber type GF30PA1010, making the printed structure have high strength, high rigidity and high dimensional stability;

[0085] In Step 3, during the powder laying process, the system evenly lays the powder on the surface of the printing platform through a doctor blade to ensure that the powder thickness of each layer is consistent;

[0086] In Step 4, the laser power is set at 25W, the spiral scanning mode is adopted to improve the sintering effect, the linear filling mode is adopted, the filling density is 100%, the scanning speed is set at 10mm / s, and the layer thickness is set at 0.05mm to balance the printing accuracy and efficiency; the natural cooling method is adopted, and the cooling speed is controlled between 2°C / min - 6°C / min to avoid warping or cracking of the parts caused by thermal stress due to too fast cooling speed, and to avoid prolonging the printing cycle due to too slow cooling.

[0087] In the present invention, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An aircraft wing skin, characterized in that: It includes a first panel, a second panel and a middle layer panel. The middle layer panel includes a number of superlattice blocks, and each of the superlattice blocks is arranged in a flat and sequential manner. The superlattice block includes a first plate, a second plate, a cross bar, at least one first truss and at least one second truss. The first plate is fixedly connected to the first panel, the second plate is fixedly connected to the second panel, the cross bar is placed on a cross bar plane in the middle of the first plate and the second plate, the cross bar plane, the first plate and the second plate are parallel, the cross bar plane is perpendicular to the center line of the superlattice block, the first truss is placed on a first truss plane, the second truss is placed on a second truss plane, and the second truss plane intersects the first truss plane at the center line of the superlattice block; the first truss has a first end, a second end, a third end and a fourth end, the first end and the second end are symmetric about the cross bar plane, the third end and the fourth end are symmetric about the center line of the superlattice block; the second truss has a fifth end, a sixth end, a seventh end and an eighth end, the fifth end and the sixth end are symmetric about the cross bar plane, the seventh end and the eighth end are symmetric about the center line of the superlattice block; the first end and the fifth end are both fixedly connected to the first plate, the second end and the sixth end are both fixedly connected to the second plate, and the third end, the fourth end, the seventh end and the eighth end are all fixedly connected to the cross bar.

2. The wing skin according to claim 1, characterized in that: The first truss includes a first truss rod, a second truss rod, a third truss rod and a fourth truss rod; the first truss rod and the second truss rod are placed between the first plate and the cross bar plane, the first end of the first truss rod and the first end of the second truss rod are both fixedly connected to the first plate, the second end of the first truss rod and the second end of the second truss rod are both fixedly connected to the cross bar, and the first truss rod and the second truss rod are symmetric about the center line of the superlattice block; the third truss rod and the fourth truss rod are placed between the second plate and the cross bar plane, the first end of the third truss rod and the first end of the fourth truss rod are both fixedly connected to the second plate, the second end of the third truss rod and the second end of the fourth truss rod are both fixedly connected to the cross bar, and the third truss rod and the fourth truss rod are symmetric about the center line of the superlattice block; the third truss rod and the first truss rod are symmetric about the cross bar plane.

3. The wing skin according to claim 2, characterized in that: The second truss includes a fifth truss rod, a sixth truss rod, a seventh truss rod, and an eighth truss rod; the fifth truss rod and the sixth truss rod are disposed between the first plate and the cross-bar plane. The first ends of the fifth truss rod and the sixth truss rod are both fixedly connected to the first plate, and the second ends of the fifth truss rod and the sixth truss rod are both fixedly connected to the cross-bar. The fifth truss rod and the sixth truss rod are symmetric about the center line of the superlattice block; the seventh truss rod and the eighth truss rod are disposed between the second plate and the cross-bar plane. The first ends of the seventh truss rod and the eighth truss rod are both fixedly connected to the second plate, and the second ends of the seventh truss rod and the eighth truss rod are both fixedly connected to the cross-bar. The seventh truss rod and the eighth truss rod are symmetric about the center line of the superlattice block; the seventh truss rod and the fifth truss rod are symmetric about the cross-bar plane.

4. The wing skin according to claim 3, characterized in that: The first truss rod, the second truss rod, the third truss rod, and the fourth truss rod are all first curved rods, and the first curved rods are recessed in a direction approaching the cross-bar; the fifth truss rod, the sixth truss rod, the seventh truss rod, and the eighth truss rod are all second curved rods, and the second curved rods are convex in a direction away from the cross-bar.

5. The wing skin according to claim 4, wherein: The expression of the center line of the first curved rod is: Among them, C1(u) is the point on the center line of the first curved rod at parameter u, P i is a control point, P0 is the endpoint of the first end of the first curved rod, P3 is the endpoint of the second end of the first curved rod, P1 and P2 are two points between the endpoint of the first end of the first curved rod and the endpoint of the second end of the first curved rod, w i is the weight corresponding to the control point, N i,p (u) is a basis function, where p is the degree of the curve, p takes 3, u is a parameter within the knot vector, u ∈ [0, 1], and i takes 0, 1, 2, or 3; The expression of the center line of the second curved rod is: Among them, C2(u) is the point on the center line of the second bending rod at parameter u, P i is a control point, P4 is the endpoint of the first end of the second bending rod, P7 is the endpoint of the second end of the second bending rod, P5 and P6 are two points between the endpoint of the first end of the second bending rod and the endpoint of the second end of the second bending rod, w i is the weight corresponding to the control point, N i,p (u) is a basis function, where p is the degree of the curve, p takes 3, u is the parameter within the knot vector, u ∈ [0, 1], and i takes 4, 5, 6, or 7.

6. The wing skin according to claim 3, wherein: The number of the first trusses is one, the number of the second trusses is one, and the second truss plane is perpendicular to the first truss plane; the outer shape of the superlattice block is a cube; the first panel, the second panel, and the middle layer panel are all glass fiber reinforced nylon 1010 plates.

7. The wing skin according to claim 1, characterized in that: The superlattice block further includes at least three support rods, and each of the support rods is disposed around the center line of the superlattice block. One end of each support rod is fixedly connected to the first plate, and the other end of each support rod is fixedly connected to the second plate.

8. An airfoil, characterized in that: Including the wing skin according to any one of claims 1 to 7.

9. A tiltrotor aircraft, characterized in that: Including the wing according to claim 8.

10. A manufacturing method of a wing skin for manufacturing the wing skin according to any one of claims 1 to 7, characterized in that: Including the following steps: Step 1: Design and document preparation, use computer-aided design software to design a three-dimensional model of the middle layer panel, and convert the model into a format for SLS printing through slicing software to generate the printing path for each layer; Step 2: Select powder materials; Step 3: Perform powder laying and temperature control and setting, and set the temperatures of the cavity, the printing platform, and the nozzle according to the selected powder materials; Step 4: Perform laser sintering. The laser passes through a computer-controlled scanning system and sinters the powder materials layer by layer according to a predetermined path. The powder particles are melted and fused. After each layer of printing is completed, the laser stops working and waits to cool to room temperature to form a solid layer; sinter and cool and solidify layer by layer until the cooling and solidification of the last layer are completed, and finally construct a three-dimensional model, and the printing of the middle layer panel ends; Step Five: Fix and cover the first panel and the second panel on both sides of the middle layer board to obtain the wing skin.

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