Bionic vibration reduction, drag reduction and anti-icing wing skin and preparation method thereof

Abstract

The present invention discloses a bionic vibration reduction, drag reduction and anti-icing wing skin and a preparation method thereof, which belongs to the field of aerospace. The structure of the present invention is inspired by the honeycomb structure and the micro-nano structure of the shark skin surface. The present invention combines the sandwich structure with the surface micro-nano structure to realize the multifunctional integrated design of the wing skin, effectively improve the comprehensive performance of the wing, and the prepared bionic vibration reduction, drag reduction and anti-icing wing skin has strong machinability, not only has the high strength and high damping effect of nickel-titanium alloy, but also has a strong vibration reduction ability of the prepared sandwich structure, which can effectively reduce the wing flutter of high-speed aircraft.

Description

Technical Field

[0001] The invention belongs to the field of aerospace, and in particular, relates to a bionic vibration reduction, drag reduction and icing prevention wing skin and a preparation method thereof. Background Art

[0002] With the continuous development of aerospace, aircraft skin structure, as a frontier field of aerospace, has received a lot of attention and research. In some high-speed aircraft, especially in the field of ultra-high-speed aircraft, the resistance of the aircraft wing increases sharply, and the vibration and icing problems caused often greatly reduce the stability and aerodynamics of the aircraft, and even cause many safety accidents. Most of the existing aircraft skins adopt hollow structures, single honeycomb structures or "V"-shaped structures. When facing the use environment of high-speed aircraft, they still have the disadvantages of low manufacturability, large mass, weak vibration suppression ability, and easy icing at low temperatures. The resulting poor safety, durability and reliability have seriously restricted the development of high-speed aircraft. Therefore, the development of high-speed aircraft skin structures with high-efficiency vibration reduction and anti-icing has become an urgent need in the current and even future aviation equipment fields.

[0003] In daily observation, the honeycomb structure has good vibration reduction and sound absorption properties, while the micro-nano structure on the surface of shark skin can provide sharks with good hydrophobicity and drag reduction properties. At the same time, nickel-titanium alloy is the most commonly used shape memory alloy, with excellent functional properties such as shape memory, superelasticity, high strength and high damping. The emergence of additive manufacturing technology can not only solve the problem that nickel-titanium alloy is difficult to process, but also can quickly form complex skin sandwich structures. Therefore, inspired by honeycomb and shark skin, the combination of additive manufacturing and femtosecond laser subtractive manufacturing can prepare wing skins with both vibration reduction and drag reduction properties and anti-icing properties, thereby improving the aerodynamics and flight stability of high-speed aircraft.

[0004] Therefore, designing a bionic vibration-reducing, drag-reducing and icing-resistant wing skin is in line with actual needs and has certain practical value. Summary of the invention

[0005] In view of the above problems existing in the prior art, an object of the present invention is to provide a bionic vibration reduction, drag reduction and anti-icing wing skin and a preparation method thereof.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a bionic vibration reduction, drag reduction and anti-icing wing skin, comprising a sandwich structure, the sandwich structure comprising a plurality of sandwich structure units, the sandwich structure unit is divided into three layers, including an upper layer, a lower layer and a middle layer;

[0008] The upper and lower layers of the sandwich structure unit are both honeycomb hexagonal structures or both triangular structures;

[0009] The middle layer of the sandwich structure unit is a combination of inwardly curved cylinders and outwardly protruding square prisms;

[0010] The inwardly curved cylinders connect the vertices of the upper and lower layers of the hexagonal structures or triangular structures, and the inwardly curved cylinders are symmetrically arranged in a circular array;

[0011] The outwardly protruding prisms connect the midpoints of the edges of the upper and lower layers of hexagonal structures or triangular structures, and the outwardly protruding prisms are symmetrically arranged in a circular array;

[0012] A plurality of sandwich structure units are arranged in an array to form a multi-layer sandwich structure, wherein the upper surface of the uppermost sandwich structure unit in the sandwich structure and the lower surface of the lowermost sandwich structure unit in the sandwich structure are closed structures and serve as skin surfaces.

[0013] The present invention also provides a method for preparing a bionic vibration reduction, drag reduction and anti-icing wing skin, which is used to prepare the bionic vibration reduction, drag reduction and anti-icing wing skin, comprising the following steps:

[0014] Step 1: According to the different functions of different positions of the wing, two sandwich structure units of the wing skin are designed for different parts of the wing and three-dimensional modeling is performed;

[0015] Step 2: Print and prepare a sandwich structure made of nickel-titanium alloy based on laser powder bed molten metal additive manufacturing technology;

[0016] Step three, use femtosecond laser technology to scan the skin surface of the sandwich structure of nickel-titanium alloy, generate a bionic micro-nano structure on its surface, and after standing in the air for a period of time, obtain a super-hydrophobic skin surface with a micro-nano structure that has anti-icing and drag reduction functions.

[0017] Furthermore, in step 1, the specific method for designing the skin sandwich structure unit is:

[0018] The sandwich structure unit is divided into three layers, including an upper layer, a lower layer and a middle layer. The upper and lower layers are both honeycomb hexagonal structures or triangular structures. The middle layer is a vibration reduction layer connecting the upper and lower layers. According to the Bezier curve principle, the curve equations of the inwardly curved cylinders in the middle layer and the curve equations of the outwardly protruding square prisms are designed.

[0019] The inwardly curved cylinders connect the vertices of the upper and lower layers of hexagonal structures or triangular structures and are connected symmetrically in a circular array;

[0020] The outwardly protruding prisms connect the midpoints of the edges of the upper and lower layers of hexagonal structures or triangular structures and are connected symmetrically in a circular array;

[0021] After multiple sandwich structure units are arranged in an array to form a multi-layer sandwich structure, the upper surface of the sandwich structure unit in the uppermost layer of the sandwich structure and the lower surface of the sandwich structure unit in the lowermost layer of the sandwich structure are designed to be in a closed state and serve as skin surfaces, and the middle multi-layer sandwich structure units are all in a hollow state.

[0022] Furthermore, the curve equation of the inwardly curved cylinder is:

[0023] ;

[0024] The curve equation of the outwardly protruding square prism is:

[0025] ;

[0026] Where t is a parameter in the range [0, 1], , are the coordinates of the starting point of the curve, It is the vertex of the hexagonal or triangular structure of the upper layer of the sandwich structure unit. It is the midpoint of the edge of the hexagonal or triangular structure of the upper layer of the sandwich structure unit. , is the coordinate of the midpoint of the curve, that is, the midpoint of the middle layer of the sandwich structure unit, , is the coordinate of the end point of the curve, It is the vertex of the hexagonal or triangular structure of the lower layer of the sandwich structure unit. It is the midpoint of the edge of the hexagonal structure or triangular structure of the lower layer of the sandwich structure unit.

[0027] Furthermore, in step 2, the specific method for preparing the sandwich structure made of nickel-titanium alloy is:

[0028] The model obtained in step 1 is saved in a format that can be used by laser powder bed molten metal additive manufacturing technology equipment. After the model is sliced, it is imported into the control software of the printing equipment. The water cooling cycle is turned on, the substrate and the scraper are installed, and the nickel-titanium alloy powder with a median diameter of 35 μm and a nearly equiatomic ratio is placed in the printer powder bin. High-purity argon gas is introduced into the printing chamber. After the oxygen content in the molding chamber is lower than 0.03%, a strip scanning strategy with a laser power of 125 W, a scanning speed of 600 mm / s, a scanning spacing of 0.08 mm, a layer thickness of 0.03 mm, and a scanning angle of 47° is used to start preparing a sandwich structure made of nickel-titanium alloy.

[0029] Furthermore, in step 3, the specific method for preparing the bionic micro-nano structure on the skin surface is:

[0030] The prepared nickel-titanium alloy sandwich structure was placed on a fixed platform of a laser processing platform. In an air environment, a laser processing strategy with a pulse width of 270fs, a wavelength of 350nm, an average power of 0.4W, a scanning speed of 100mm / s, and a scanning number of 15 times was adopted. The skin surface was processed with a triangular shield scale structure imitating the shark skin surface by moving the laser processing platform and cooperating with a femtosecond laser. After the processing was completed, it was left to stand in the air for 14 days to reduce the surface energy of the skin surface. Finally, a super-hydrophobic skin surface with a micro-nano structure with anti-icing and drag reduction functions was obtained.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The structure of the present invention is inspired by the honeycomb structure and the micro-nano structure of the shark skin surface. The prepared bionic vibration reduction, drag reduction and anti-icing wing skin has strong machinability. It not only has the high strength and high damping effect of nickel-titanium alloy, but also the prepared sandwich structure has strong vibration reduction ability, which can effectively reduce the wing flutter of high-speed aircraft.

[0033] The present invention is different from the traditional single sandwich structure or single drag reduction and anti-icing surface. The present invention combines the sandwich structure with the surface micro-nano structure to achieve a multifunctional integrated design of the wing skin, effectively improving the comprehensive performance of the wing.

[0034] The present invention utilizes additive manufacturing technology to prepare two sandwich structures and use them for different parts of the wing respectively. This not only solves the problem of large tool wear during traditional nickel-titanium alloy processing, but also gives the sandwich structure the ability to quickly form, reducing the time cost of production and manufacturing. Moreover, according to the functions and performance requirements of different parts of the wing, the performance improvement of the wing by the sandwich structure is maximized. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a flow chart for preparing the bionic vibration reduction, drag reduction and anti-icing wing skin.

[0036] Figure 2 This is a structural diagram of a sandwich structure unit of a hexagonal skin sandwich structure in the present invention.

[0037] Figure 3 It is a structural diagram of the sandwich structure unit of the triangular skin sandwich structure in the present invention.

[0038] Figure 4 This is a diagram showing the skin effect of the hexagonal skin sandwich structure after femtosecond laser processing in the present invention.

[0039] Figure 5 This is a skin effect diagram of the triangular skin sandwich structure after femtosecond laser processing in the present invention.

[0040] Figure 6It is a schematic diagram of the covering position of the skin structure in the present invention.

[0041] In the figure: 1, laser powder bed fusion printing equipment; 2, nickel-titanium alloy powder; 3, hexagonal skin sandwich structure; 4, triangular skin sandwich structure; 5, femtosecond laser; 6, femtosecond laser processing platform; 7, hexagonal bionic vibration reduction, drag reduction and anti-icing wing skin; 8, triangular bionic vibration reduction, drag reduction and anti-icing wing skin. DETAILED DESCRIPTION

[0042] In order to better illustrate the preparation process involved in the present invention and its advantages over the prior art, further explanation will be given based on the accompanying drawings.

[0043] A bionic vibration reduction, drag reduction and anti-icing wing skin provided by the present invention includes a sandwich structure, which includes a plurality of sandwich structure units, which are arranged in combination according to their shape structures in the lateral arrangement, and are stacked in the longitudinal multi-layer arrangement according to the position of each sandwich structure unit.

[0044] The sandwich structure unit is divided into three layers as a whole, including an upper layer, a lower layer and a middle layer. The upper and lower layers of the sandwich structure unit are both honeycomb hexagonal structures or both are triangular structures. The middle layer of the sandwich structure unit is a combination of inwardly curved cylinders and outwardly protruding square prisms. The inwardly curved cylinders connect the vertices of the hexagonal structures or triangular structures of the upper and lower layers, and the inwardly curved cylinders are symmetrically connected in a circular array. The outwardly protruding prisms connect the midpoints of the edges of the hexagonal structures or triangular structures of the upper and lower layers, and the outwardly protruding prisms are symmetrically connected in a circular array. Multiple sandwich structure units are arranged in an array to form a multi-layer sandwich structure. The upper surface of the sandwich structure unit of the uppermost layer in the sandwich structure and the lower surface of the sandwich structure unit of the lowermost layer in the sandwich structure are closed structures and serve as skin surfaces.

[0045] like Figure 4 and Figure 5 As shown, the present solution provides two types of bionic vibration reduction, drag reduction and anti-icing wing skins, namely a hexagonal bionic vibration reduction, drag reduction and anti-icing wing skin 7 and a triangular bionic vibration reduction, drag reduction and anti-icing wing skin 8.

[0046] like Figure 1 As shown, the preparation method thereof comprises the following steps:

[0047] Step 1: According to the different functions of different positions of the wing, two sandwich structure units of the wing skin are designed for different parts of the wing and three-dimensional modeling is performed;

[0048] Step 2: Based on the laser powder bed fusion (L-PBF) metal additive manufacturing technology, use a suitable 3D printing device (i.e. Figure 1Laser powder bed fusion printing equipment in 1) Preparation of sandwich structures made of nickel-titanium alloy;

[0049] Step three, use femtosecond laser technology to scan the skin surface of the sandwich structure made of nickel-titanium alloy, generate bionic micro-nano structure on its surface, and let it stand in the air for 14 days to obtain a super-hydrophobic skin surface with micro-nano structure that has anti-icing and drag reduction functions.

[0050] like Figure 2 As shown, the dimensions of the sandwich structure unit of the hexagonal skin sandwich structure 3 are as follows: overall height h=10mm, length a=10mm, side length c=5.77mm, middle layer height b=6mm, hexagonal structure thickness e=2mm, hexagonal structure width d=2mm, the concave cylinder and the convex prism are both fitted with the Bezier curve, the diameter of the concave cylinder is 2mm, and the side length of the convex prism is 2mm.

[0051] like Figure 3 As shown, the dimensions of the sandwich structure unit of the triangular skin sandwich structure 4 are as follows: overall height h=10mm, side length c=10mm, middle layer height b=6mm, triangular structure thickness e=2mm, triangular structure width d=2mm, the concave cylinder and the convex prism are both fitted with the Bezier curve, the diameter of the concave cylinder is 2mm, and the side length of the convex prism is 2mm.

[0052] Since the honeycomb design of the sandwich structure units of the hexagonal skin sandwich structure 3 has better vibration reduction and sound absorption characteristics, the sandwich structure units of the hexagonal skin sandwich structure 3 are closely arranged and covered on the wing part close to the engine, while the sandwich structure units of the triangular skin sandwich structure 4 are triangular in design and have good stability, so the sandwich structure units of the triangular skin sandwich structure 4 are closely arranged and covered on other parts of the wing. The specific covering positions of the two sandwich structures are as follows: Figure 6 Both sandwich structures are formed by arranging sandwich structure units in multiple layers, the upper surface of the sandwich structure unit in the uppermost layer of the sandwich structure and the lower surface of the sandwich structure unit in the lowermost layer of the sandwich structure are designed to be closed and used as the skin surface, and the middle multi-layer sandwich structure units are all hollowed out, and finally two skin sandwich structures are obtained.

[0053] In step 1, the specific method of sandwich structure unit design is:

[0054] The sandwich structure unit is divided into three layers, and the upper and lower layers are both honeycomb hexagonal structures or triangular structures. In order to obtain excellent vibration reduction performance, the curve equations of the inwardly curved cylinders in the middle layer and the curve equations of the outwardly protruding square prisms are designed according to the Bezier curve principle;

[0055] The inwardly curved cylinders connect the vertices of the upper and lower layers of the hexagonal structures or triangular structures, and the inwardly curved cylinders are symmetrically connected in a circular array;

[0056] The outwardly protruding prisms connect the midpoints of the edges of the upper and lower layers of hexagonal structures or triangular structures, and the outwardly protruding prisms are symmetrically connected in a circular array;

[0057] After multiple sandwich structure units are arranged in an array to form a multi-layer sandwich structure, the upper surface of the sandwich structure unit in the uppermost layer of the sandwich structure and the lower surface of the sandwich structure unit in the lowermost layer of the sandwich structure are designed to be in a closed state and serve as skin surfaces, and the middle multi-layer sandwich structure units are all in a hollow state.

[0058] The inwardly curved cylinders and the outwardly protruding square prisms in the middle layer of the sandwich structure unit are designed according to the principle of quadratic Bezier curves, and are connected by multiple control points in a specific proportion. The curve shape and curvature can be flexibly controlled according to actual needs, and have good fluency and high precision. The inwardly curved cylinder mainly plays the role of energy dissipation, vibration absorption and energy absorption. The outwardly protruding square prisms are mainly used for the connection between the upper and lower layers of the sandwich structure unit and between units, and play the role of energy transfer and fixation. When encountering vibration, when the middle layer designed by this curve is slightly deformed, due to the good fluency of the curve and the flexible change of curvature, the energy generated by the vibration can be transferred to the inwardly curved cylinder and the outwardly protruding square prism through the upper and lower layer connection nodes of the sandwich structure unit. The inwardly curved cylinder will first dissipate some of the energy generated by the vibration, and the remaining energy will be transferred between units through the outwardly protruding square prisms. After another energy dissipation, the amplitude of the vibration is reduced, providing excellent anti-vibration performance.

[0059] The curve equation used for the inward-bending cylinder above is:

[0060] ;

[0061] The curve equation used by the above-mentioned outward-protruding square prism is:

[0062] ;

[0063] Where t is a parameter in the range [0, 1], , are the coordinates of the starting point of the curve, It is the vertex of the hexagonal or triangular structure of the upper layer of the sandwich structure unit. It is the midpoint of the edge of the hexagonal or triangular structure of the upper layer of the sandwich structure unit. , is the coordinate of the midpoint of the curve, that is, the midpoint of the middle layer of the sandwich structure unit, , is the coordinate of the end point of the curve, It is the vertex of the hexagonal or triangular structure of the lower layer of the sandwich structure unit. It is the midpoint of the edge of the hexagonal structure or triangular structure of the lower layer of the sandwich structure unit.

[0064] In step 2, the specific method for preparing the sandwich structure of nickel-titanium alloy is:

[0065] The model obtained in step one is saved in a format that can be used by laser powder bed molten metal additive manufacturing technology equipment. After the model is sliced, it is imported into the control software of the printing equipment. The water cooling cycle is turned on, the substrate and the scraper are installed, and the nickel-titanium alloy powder 2 with a median diameter of 35 μm and a nearly equiatomic ratio is placed in the printer powder bin. High-purity argon gas is introduced into the printing chamber. After the oxygen content in the molding chamber is lower than 0.03%, a strip scanning strategy with a laser power of 125 W, a scanning speed of 600 mm / s, a scanning spacing of 0.08 mm, a layer thickness of 0.03 mm, and a scanning angle of 47° is used to start preparing the hexagonal skin sandwich structure 3 and the triangular skin sandwich structure 4.

[0066] In the step three, the specific method for preparing the bionic micro-nano structure on the skin surface is: the prepared hexagonal skin sandwich structure 3 and the triangular skin sandwich structure 4 are respectively placed on the fixed platform of the femtosecond laser processing platform 6, and a laser processing strategy with a pulse width of 270fs, a wavelength of 350nm, an average power of 0.4W, a scanning speed of 100mm / s, and a scanning number of 15 times is adopted in an air environment. The femtosecond laser processing platform 6 moves along a triangular path, and cooperates with the femtosecond laser 5 to process the triangular shield scale structure of the skin surface imitating the shark skin surface.

[0067] The dimensions of the micro-nano structural units on the shark skin-like surface are as follows: the base length of the triangle is 20 μm, the two sides are 35 μm long, and the spacing between patterns is 40 μm. After processing is completed, the surface energy of the skin is reduced by standing in the air for 14 days to obtain a hexagonal bionic vibration reduction, drag reduction and anti-icing wing skin 7 and a triangular bionic vibration reduction, drag reduction and anti-icing wing skin 8.

Claims

1. A method for preparing a bionic vibration reduction, drag reduction and anti-icing wing skin, characterized in that: The following steps are involved: Step 1: According to the different functions of different positions of the wing, two sandwich structure units of the wing skin are designed for different parts of the wing and three-dimensional modeling is performed; Step 2: Print and prepare a sandwich structure made of nickel-titanium alloy based on laser powder bed molten metal additive manufacturing technology; Step 3: Use femtosecond laser technology to scan the skin surface of the sandwich structure of nickel-titanium alloy to generate a bionic micro-nano structure on the surface, and after standing in the air for a period of time, obtain a super-hydrophobic skin surface with a micro-nano structure having anti-icing and drag reduction functions; In the step 1, the specific method of sandwich structure unit design is: The sandwich structure unit is divided into three layers, including an upper layer, a lower layer and a middle layer. The upper and lower layers are both honeycomb hexagonal structures or triangular structures. The middle layer is a vibration reduction layer connecting the upper and lower layers. According to the Bezier curve principle, the curve equations of the inwardly curved cylinders in the middle layer and the curve equations of the outwardly protruding square prisms are designed. The inwardly curved cylinders connect the vertices of the upper and lower layers of hexagonal structures or triangular structures and are connected symmetrically in a circular array; The outwardly protruding prisms connect the midpoints of the edges of the upper and lower layers of hexagonal structures or triangular structures and are connected symmetrically in a circular array; After multiple sandwich structure units are arranged in an array to form a multi-layer sandwich structure, the upper surface of the sandwich structure unit in the uppermost layer of the sandwich structure and the lower surface of the sandwich structure unit in the lowermost layer of the sandwich structure are designed to be in a closed state and serve as skin surfaces, and the middle multi-layer sandwich structure units are all in a hollow state.

2. The method for preparing a bionic vibration reduction, drag reduction and anti-icing wing skin according to claim 1, characterized in that: The curve equation of the inwardly curved cylinder is: ； The curve equation of the outwardly protruding square prism is: ； Where t is a parameter in the range [0, 1], , are the coordinates of the starting point of the curve, It is the vertex of the hexagonal or triangular structure of the upper layer of the sandwich structure unit. It is the midpoint of the edge of the hexagonal or triangular structure of the upper layer of the sandwich structure unit. , is the coordinate of the midpoint of the curve, that is, the midpoint of the middle layer of the sandwich structure unit, , is the coordinate of the end point of the curve, It is the vertex of the hexagonal or triangular structure of the lower layer of the sandwich structure unit. It is the midpoint of the edge of the hexagonal structure or triangular structure of the lower layer of the sandwich structure unit.

3. The method for preparing a bionic vibration reduction, drag reduction and anti-icing wing skin according to claim 1, characterized in that: In the step 2, the specific method for preparing the sandwich structure made of nickel-titanium alloy is: The model obtained in step 1 is saved in a format that can be used by laser powder bed molten metal additive manufacturing technology equipment. After the model is sliced, it is imported into the control software of the printing equipment. The water cooling cycle is turned on, the substrate and the scraper are installed, and the nickel-titanium alloy powder with a median diameter of 35 μm and a nearly equiatomic ratio is placed in the printer powder bin. High-purity argon gas is introduced into the printing chamber. After the oxygen content in the molding chamber is lower than 0.03%, a strip scanning strategy with a laser power of 125 W, a scanning speed of 600 mm / s, a scanning spacing of 0.08 mm, a layer thickness of 0.03 mm, and a scanning angle of 47° is used to start preparing a sandwich structure made of nickel-titanium alloy.

4. The method for preparing a bionic vibration reduction, drag reduction and anti-icing wing skin according to claim 1, characterized in that: In the step 3, the specific method for preparing the bionic micro-nano structure on the skin surface is: The prepared sandwich structure of nickel-titanium alloy is placed on a fixed platform of the laser processing platform. In the air environment, a laser processing strategy with a pulse width of 270fs, a wavelength of 350nm, an average power of 0.4W, a scanning speed of 100mm / s and a scanning number of 15 times is adopted. The skin surface is processed with a triangular shield scale structure imitating the shark skin surface by moving the laser processing platform and cooperating with a femtosecond laser. After the processing is completed, it is left to stand in the air for 14 days to reduce the surface energy of the skin surface. Finally, a super-hydrophobic skin surface with a micro-nano structure with anti-icing and drag reduction functions is obtained.

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