High-speed aircraft skin structure and manufacturing method

Abstract

The invention discloses a high-speed aircraft skin structure and a manufacturing method, and belongs to the technical field of aircraft skin design. The skin structure comprises a bearing-high temperature resistant substrate and a radiation and stealth integrated metasurface antenna embedded in the substrate. The invisible integrated metasurface antenna comprises a slotted metal microstrip layer located at the top, a metal through hole located in the middle and a feed network structure located at the bottom. The bearing-high-temperature-resistant substrate is of a double-layer structure, the upper layer is a microstrip line substrate, the lower layer is a feed network substrate, and the microstrip line substrate and the feed network substrate are provided with aligned vertical via holes. The high-speed aircraft skin has the comprehensive capacity of invisibility, information transmission, bearing and high-temperature resistance.

Description

Technical Field

[0001] The present invention relates to a high-speed aircraft skin structure and a manufacturing method, and in particular to a high-speed aircraft stealth-transmission-load-bearing-high-temperature-resistant integrated skin structure and a manufacturing method. Background Art

[0002] The competition for electromagnetic dominance is becoming increasingly fierce in modern warfare, and electromagnetic space security has risen to a new level. High-speed penetration equipment plays an important role in the competition for electromagnetic dominance, and high-performance electromagnetic radiation is the cornerstone of the interconnection and efficient penetration of high-speed penetration equipment. Efficient electromagnetic stealth is an effective way to ensure equipment safety and improve offensive and defensive effectiveness. Therefore, in order to improve the combat power and survivability of penetration equipment in complex electromagnetic environments, it is required to have both high-performance guidance / communication and efficient electromagnetic stealth characteristics. As the main radiation source and scattering source on high-speed penetration equipment, the antenna must meet the requirements of high-flexibility radiation and strong electromagnetic stealth at the same time. How to maximize the antenna radiation capability while realizing electromagnetic stealth characteristics is particularly important for penetration equipment that is restricted by long detection / communication distances and limited energy sources.

[0003] However, since the electromagnetic functional structure has strict working temperature requirements and cannot withstand the high aerodynamic heat and extreme loads during flight, the current equipment antenna-antenna design generally adopts a complex three-layer design of thermal insulation layer-frequency-selective supersurface stealth layer-antenna radiation surface. When the antenna receives and transmits electromagnetic waves, the electromagnetic waves need to pass through the thermal insulation layer and the electromagnetic surface twice, resulting in serious energy loss, which limits the effective improvement of the antenna detection capability. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a high-speed aircraft skin structure and a manufacturing method, including a load-bearing-high temperature resistant substrate and a radiation and stealth integrated metasurface antenna embedded therein, so as to realize the high-speed aircraft skin with the comprehensive capabilities of stealth, communication, load-bearing and high temperature resistance.

[0005] The technical solution of the present invention is:

[0006] A high-speed aircraft skin structure, comprising a load-bearing and high-temperature resistant matrix and a radiation and stealth integrated metasurface antenna embedded in the load-bearing and high-temperature resistant matrix;

[0007] The radiation and stealth integrated metasurface antenna comprises a slotted metal microstrip layer at the top, a metal through hole at the middle, and a feed network structure at the bottom;

[0008] The load-bearing and high-temperature resistant substrate is a double-layer structure, the upper layer is a microstrip line substrate, and the lower layer is a feed network substrate. The microstrip line substrate and the feed network substrate have aligned vertical vias; wherein the microstrip line substrate is a plane or curved surface structure with a continuous surface, and a periodic lattice structure is filled inside.

[0009] Furthermore, the slotted metal microstrip layer is provided with a plurality of slotted metal microstrips; a feeding network structure is provided directly below each slotted metal microstrip, and the feeding network structure and the slotted metal microstrip are connected via a metal through hole provided in the metal ground isolation layer to form a unit structure together.

[0010] Furthermore, all unit structures are designed for array formation and divided into four sub-arrays, and the slotted metal microstrips in each sub-array are placed at the same angle; among them, the placement angles of the slotted metal microstrips in two sub-arrays on the same diagonal are the same, and the placement angles of the slotted metal microstrips in sub-arrays on different diagonals are perpendicular to each other.

[0011] Furthermore, the slotted metal microstrip is a radiation structure with stealth performance. The length and width of the slotted metal microstrip are determined through simulation so that the current of the slotted metal microstrip and the current of the metal ground in the stealth frequency band are opposite, showing magnetic resonance characteristics.

[0012] Furthermore, the center of the slotted metal microstrip is slotted along the long side of the microstrip, and the slotting achieves the polarization conversion reflection performance in the radiation frequency band while not affecting the polarization conversion reflection performance in the stealth frequency band.

[0013] Furthermore, the feeding network structure has the same amplitude as the corresponding slotted metal microstrip and adopts circular polarization sequential feeding; the feeding network structure also has fan-shaped branches, and impedance matching with the microstrip feeder is achieved by adjusting the geometric parameters of the fan-shaped branches.

[0014] Furthermore, the connection position between the slotted metal microstrip and the metal through hole is located in the middle of the long side of the slotted metal microstrip, and the connection position between the feed network structure and the metal through hole is located at the center point of the fan-shaped branch.

[0015] Furthermore, the microstrip line matrix material is a composite of one or more of aluminum oxide, silicon oxide, silicon carbide, silicon nitride, hollow silicon-based ceramics, and hollow aluminum-based ceramics.

[0016] A method for manufacturing a high-speed aircraft skin structure, comprising:

[0017] The length and width of the slotted metal microstrip and the length and width of the slot in the top radiating metal layer are determined according to the required antenna operating frequency, and then the feeding network structure of the loaded fan-shaped branches with equal amplitude and circular polarization sequential feeding at the bottom is designed according to the position of the slotted metal microstrip;

[0018] Through photocuring ceramic additive manufacturing, a load-bearing and high-temperature resistant substrate with vertical vias is prepared. The load-bearing and high-temperature resistant substrate is divided into two parts, the upper part is the microstrip line substrate, and the lower part is the feed network substrate;

[0019] Through the selective laser activation process, a slotted metal microstrip is prepared on the top of the microstrip line substrate, a metal ground shielding layer is prepared on the top of the feed network substrate, and a feed network structure is prepared on the bottom;

[0020] The preparation of the integrated radiation and stealth metasurface antenna is completed by connecting the slotted metal microstrip and the feeding network structure with the vertical through-hole equal-diameter conductor;

[0021] Fill each joint with high temperature resistant inorganic glue and dry it; wherein, the high temperature resistant inorganic glue includes silicone glue, silicate glue and aluminate glue, and the use temperature is not less than 300°C.

[0022] Furthermore, a laser etching process is used to optimize the accuracy of the vertical via holes of the load-bearing and high-temperature resistant substrate, so that the via hole accuracy is better than 0.1 mm'.

[0023] The advantages of the present invention compared with the prior art are:

[0024] (1) While ensuring electromagnetic stealth performance, the present invention significantly improves the detection capability of high-speed aircraft. The present invention breaks the traditional design framework of loading stealth electromagnetic surface antenna cover based on antenna radiation, integrates radiation function and RCS reduction function into the same structure, and constructs a metasurface antenna that integrates radiation and stealth. This avoids the problem of serious energy loss caused by electromagnetic waves passing through the thermal insulation layer and the electromagnetic surface twice when the antenna receives and transmits electromagnetic waves, thus breaking through the bottleneck of the detection capability of high-speed aircraft antennas. It effectively reduces the out-of-band RCS of the antenna while maintaining the in-band radiation performance.

[0025] (2) The present invention adopts a high-temperature resistant ceramic matrix to replace the traditional metamaterial composite medium, which greatly improves the load-bearing and high-temperature resistance capabilities of the radiation and stealth integrated metasurface antenna. Furthermore, based on its improved load-bearing and high-temperature resistance capabilities, the thermal insulation layer and load-bearing structure of the traditional high-speed aircraft skin structure can be combined with the high-radiation and stealth integrated metasurface antenna to realize the stealth-transmission-load-bearing-high-temperature resistance integrated skin manufacturing of high-speed aircraft. By subtracting a large amount of volume and weight from the traditional thermal insulation layer and load-bearing structure for high-speed aircraft, the high-speed aircraft can be lightweighted and energy efficiency can be improved, while reducing structural complexity, saving processing costs and shortening manufacturing and assembly cycles.

[0026] (3) The preparation method based on ceramic additive manufacturing technology and selective laser activated metallization technology proposed in the present invention has the advantages of flexible structural design and short iteration cycle. It can process hollow load-bearing and high-temperature resistant matrix structures with lattice structures and electromagnetic metamaterials with three-dimensional resonant structures that are difficult to manufacture with traditional processes, and provide advantages such as shock absorption, heat insulation, and wide-band and wide-angle stealth that are difficult to achieve with traditional structures. It realizes the integrated manufacturing of temperature-resistant and heat-insulating matrix, electromagnetic metasurface and array antenna structure, and realizes the characteristics of temperature resistance and heat insulation, high-performance radiation stealth, conformal high aerodynamics, high antenna gain, high load-bearing capacity, etc., breaking through the bottleneck of the traditional antenna-antenna system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 This is a schematic diagram of a high-speed aircraft skin structure unit according to an embodiment of the present invention;

[0029] Figure 2 Schematic diagram of the design of the skin structure unit subarray according to an embodiment of the present invention, (a) is a schematic diagram of the arrangement of the top slotted metal microstrip layer, and (b) is a schematic diagram of the connection between the top slotted metal microstrip layer and the bottom feed network structure;

[0030] Figure 3 This is a flow chart of a method for manufacturing a high-speed aircraft skin structure according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the stealth effect of a high-speed aircraft according to an embodiment of the present invention;

[0032] Figure 5 Schematic diagram of the radiation effect of a high-speed aircraft according to an embodiment of the present invention, (a) is a diagram of radiation gain, reflection coefficient and axial ratio, and (b) is a radiation pattern. DETAILED DESCRIPTION

[0033] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0034] The present invention proposes a high-speed aircraft skin structure, wherein the unit structure includes a load-bearing and high-temperature resistant matrix and a radiation and stealth integrated metasurface antenna embedded therein. The load-bearing and high-temperature resistant matrix is ​​formed by stacking ceramic slurry layer by layer through an additive manufacturing process and then firing, and the radiation and stealth integrated metasurface antenna is generated by selective laser activation metallization technology.

[0035] The integrated metasurface antenna for radiation and stealth includes a top slotted metal microstrip layer, a metal through hole in the middle, and a bottom feeding network structure. Among them, the top slotted metal microstrip layer is a metal microstrip placed at ±45°. The length and width of the metal microstrip are determined by simulation, so that the current of the metal microstrip and the current of the metal ground in the stealth frequency band are opposite, thereby presenting magnetic resonance characteristics. The center of the metal microstrip is slotted along the long side of the microstrip. The slotting achieves the polarization reflection performance of the radiation frequency band without affecting the polarization reflection performance in the stealth frequency band. The bottom is a microstrip feeding network structure and a fan-shaped branch, and impedance matching is achieved by adjusting the geometric parameters of the fan-shaped branch. The top slotted metal microstrip and the bottom feeding network structure are connected through a metal through hole. The metal through hole passes through the middle metal ground isolation layer through the opening. The connection position of the top metal radiation structure and the through hole is located in the middle of the long side, and the connection position of the bottom feeding network structure and the through hole is located at the center point of the fan-shaped branch. The top of the feeding network structure is a metal bottom isolation layer and the bottom is a fan-shaped branch.

[0036] The load-bearing and high temperature resistant substrate is composed of a double-layer structure, the upper layer is a microstrip line substrate, and the lower layer is a feed network substrate. The microstrip line substrate and the feed network substrate have aligned vertical vias. Among them, the microstrip line substrate is a plane or curved surface structure with a continuous surface, and the interior is filled with a periodic lattice structure. The thickness of the plane or curved surface structure is 0.5 to 5 mm, and the radius of curvature is greater than 50 mm. The side length of the repeating unit of the periodic lattice structure is 5 to 20 mm, the vertical height is 5 to 20 mm, and the wall thickness is 0.5 to 5 mm. The material is a composite of one or more of aluminum oxide, silicon oxide, silicon carbide, silicon nitride, hollow silicon-based ceramics, and hollow aluminum-based ceramics.

[0037] The skin structure manufacturing method proposed by the present invention is as follows Figure 3 As shown, specifically including:

[0038] 1) The length and width of the metal microstrip and the slot in the top radiating metal layer are determined according to the required antenna operating frequency, and the array is divided into four subarrays according to the array size. The placement of the two diagonal subarray metal microstrips is the same (i.e., 45° or -45°), and the two diagonal subarrays are placed perpendicular to each other. Then, according to the position of the top slotted metal microstrip, a microstrip feeding network structure with fan-shaped branches loaded with equal amplitude and circular polarization sequential feeding at the bottom is designed.

[0039] The radiation and stealth integrated metasurface antenna can simultaneously achieve efficient electromagnetic radiation within the required working frequency band while effectively reducing the radar scattering cross-sectional area outside the antenna band, thereby achieving electromagnetic stealth performance.

[0040] 2) According to the stealth-transmission-load-bearing-high temperature resistant integrated skin structure required by the design, several units suitable for ceramic additive manufacturing are designed, and the edge chamfering, suspended surface support and hole opening operations are performed according to the needs of ceramic additive manufacturing, and then each load-bearing-high temperature resistant matrix is ​​prepared by light-curing ceramic additive manufacturing technology. The load-bearing-high temperature resistant matrix is ​​divided into two parts, the upper part is the microstrip line matrix, and the lower part is the 1mm thick feed network matrix. After metallization, they are vertically interconnected by copper wires and then bonded with high-temperature inorganic glue.

[0041] 3) The laser etching process is used to optimize the accuracy of the vertical via holes in the load-bearing and high-temperature resistant substrate, so that the via hole accuracy is better than 0.1mm'.

[0042] 4) A copper conductive layer and a nickel protective layer are prepared on the surface of the load-bearing and high temperature resistant substrate by selective laser activation to obtain a top radiating metal layer and a feed network structure. (A slotted metal microstrip is prepared on the top of the microstrip line substrate by selective laser activation, and a feed network structure is prepared at the bottom of the feed network substrate).

[0043] 5) The preparation of the stealth integrated metasurface antenna is completed by connecting the slotted metal microstrip and the feeding network structure with the vertical through-hole equal-diameter conductor.

[0044] 6) Fill the joints of each component with high temperature resistant inorganic glue and dry it. The high temperature resistant inorganic glue includes silicone glue, silicate glue, and aluminate glue, and its usable temperature is not less than 300°C.

[0045] 7) Finally, fill the joints of each component with high temperature resistant inorganic glue and dry it. The high temperature resistant inorganic glue includes silicone glue, silicate glue, and aluminate glue, and its usable temperature is not less than 300°C.

[0046] The present invention will be described in detail below through specific embodiments:

[0047] The skin structure is composed of a radiation and stealth integrated metasurface antenna 2, a metal via 4 and a load-bearing and high temperature resistant substrate 1, such as Figure 1As shown, the stealth integrated metasurface antenna includes a slotted metal microstrip 3, a metal through hole 5 and a feed network structure 6. The slotted metal microstrip 3 is located on the top layer, placed at 45°, and its length and width are L = 19.5mm and w = 6.5mm respectively, while the length and width of the center slot are 15mm and 1.5mm respectively. It is worth noting that the slotted metal microstrip is a radiation structure and also bears stealth performance, that is, it realizes the integration of stealth and radiation. In addition, the bottom layer is the feed network structure 6. Since the impedance of the center of the long side of the folded dipole antenna is about 300Ω, in order to match the 50Ω microstrip feeder, the bottom layer structure includes a fan-shaped branch in addition to the feeder for impedance matching, and the radius of the fan-shaped branch is 6mm. The metal structure of the slotted metal microstrip 3 and the feed network structure 6 is connected by a metal through hole 5 with a diameter of 1mm. The overall thickness of the unit structure is t = 6.5mm, and the period P = 20mm. Then, the unit structure is designed for array formation. The array contains 8×8 units, totaling 64 units. The top metal microstrip 3 in the two groups of 4×4 sub-arrays on the upper left and lower right is placed at -45°, and the top metal microstrip 3 in the two groups of 4×4 sub-arrays on the lower left and upper right is placed at 45°. Figure 2 As shown in (a) and (b), electromagnetic stealth is achieved by reducing the rear RCS.

[0048] The load-bearing and high-temperature resistant matrix 1 is designed into four rectangular load-bearing and high-temperature resistant matrix units with an outer dimension of 80 mm × 80 mm × 5 mm. The right-angled sides of the rectangular load-bearing and high-temperature resistant matrix units are chamfered by 0.5 mm, and a supporting structure is added inside the rectangular load-bearing and high-temperature resistant matrix units to facilitate additive manufacturing.

[0049] Each load-bearing-high-temperature-resistant substrate unit 1 and the feeding network structure are printed separately by using a ceramic additive printing equipment manufacturing process through photocuring ceramic slurry, and the accuracy of the prepared load-bearing-high-temperature-resistant substrate vertical vias is optimized through a laser etching process, so that the via accuracy is better than 0.1mm'.

[0050] A copper conductive layer and a nickel protective layer are prepared on the surface of the processed load-bearing and high temperature resistant substrate unit 1 by selective laser activation, and a microstrip feeding network structure 6 with a ±45° slotted metal microstrip 3 and a loaded fan-shaped branch is obtained. The thickness of the conductive layer is 10um, and the thickness of the nickel protective layer is 5um.

[0051] By connecting the slotted metal microstrip 3 with the vertical through-hole equal-diameter conductor and the microstrip feeding network structure 6 loaded with fan-shaped branches, the preparation of the integrated radiation and stealth metasurface antenna is completed.

[0052] Finally, the high temperature resistant inorganic glue is filled into the joints of each component and dried to obtain the required high-speed aircraft stealth-transmission-load-bearing-high temperature resistant integrated skin structure.

[0053] The radiation performance and stealth performance of the high-speed aircraft stealth-transmission-load-bearing-high temperature resistance integrated skin structure were obtained through far-field testing in a darkroom. Figure 4 As shown. It can be seen that the skin structure can achieve 10dB RCS reduction in the low-frequency and high-frequency bands of 3-4.4GHz and 4.6-6.4GHz, with relative bandwidths of 38% and 33% respectively. In addition, under oblique incidence of 0-40°, the structure can maintain relatively stable RCS reduction performance. On the other hand, the impedance bandwidth of the skin structure is 4.33-4.52GHz (4.3%), the axial ratio bandwidth is 4.35-4.5GHz (3.4%), the maximum gain within the working bandwidth is 14.5dBi, and the aperture efficiency is 40%, as shown Figure 5 (a). At the same time, Figure 5 (b) shows the radiation gain patterns of the E-plane and H-plane at 4.45 GHz. It can be seen that the designed electromagnetic metasurface achieves good left-hand circular polarization radiation performance, with a sidelobe level less than -13 dB and a cross-polarization level less than -18 dB.

[0054] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-speed aircraft skin structure, characterized in that: It includes a load-bearing and high-temperature resistant substrate and a radiation and stealth integrated metasurface antenna embedded in the load-bearing and high-temperature resistant substrate; The radiation and stealth integrated metasurface antenna comprises a slotted metal microstrip layer at the top, a metal through hole at the middle, and a feed network structure at the bottom; The load-bearing and high-temperature resistant substrate is a double-layer structure, the upper layer is a microstrip line substrate, and the lower layer is a feed network substrate. The microstrip line substrate and the feed network substrate have aligned vertical vias; wherein the microstrip line substrate is a plane or curved surface structure with a continuous surface, and a periodic lattice structure is filled inside.

2. A high-speed aircraft skin structure according to claim 1, characterized in that: The slotted metal microstrip layer is provided with a plurality of slotted metal microstrips; a feeding network structure is provided directly below each slotted metal microstrip, and the feeding network structure and the slotted metal microstrip are connected through a metal through hole provided in the metal ground isolation layer to form a unit structure together.

3. A high-speed aircraft skin structure according to claim 2, characterized in that: All unit structures are designed for array formation and divided into four sub-arrays. The slotted metal microstrips in each sub-array are placed at the same angle. The slotted metal microstrips in two sub-arrays on the same diagonal are placed at the same angle, and the slotted metal microstrips in sub-arrays on different diagonals are placed at perpendicular angles to each other.

4. A high-speed aircraft skin structure according to claim 2 or 3, characterized in that: The slotted metal microstrip is a radiation structure with stealth performance. The length and width of the slotted metal microstrip are determined through simulation, so that the current of the slotted metal microstrip and the current of the metal ground in the stealth frequency band are opposite, showing magnetic resonance characteristics.

5. A high-speed aircraft skin structure according to claim 4, characterized in that: The slotted metal microstrip is slotted along the long side of the microstrip at the center, and the polarization conversion reflection performance in the radiation frequency band is achieved without affecting the polarization conversion reflection performance in the stealth frequency band through the slotting.

6. A high-speed aircraft skin structure according to claim 2, characterized in that: The feeding network structure has the same amplitude as the corresponding slotted metal microstrip and adopts circular polarization sequential feeding; the feeding network structure also has fan-shaped branches, and impedance matching with the microstrip feeder is achieved by adjusting the geometric parameters of the fan-shaped branches.

7. A high-speed aircraft skin structure according to claim 6, characterized in that: The connection position of the slotted metal microstrip and the metal through hole is located in the middle of the long side of the slotted metal microstrip, and the connection position of the feeding network structure and the metal through hole is located at the center point of the fan-shaped branch.

8. The high-speed aircraft skin structure according to claim 1, characterized in that: The microstrip line matrix material is a composite of one or more of aluminum oxide, silicon oxide, silicon carbide, silicon nitride, hollow silicon-based ceramics, and hollow aluminum-based ceramics.

9. The method for manufacturing a high-speed aircraft skin structure according to claim 2, characterized in that: include: The length and width of the slotted metal microstrip and the length and width of the slot in the top radiating metal layer are determined according to the required antenna operating frequency, and then the feeding network structure of the loaded fan-shaped branches with equal amplitude and circular polarization sequential feeding at the bottom is designed according to the position of the slotted metal microstrip; Through photocuring ceramic additive manufacturing, a load-bearing and high-temperature resistant substrate with vertical vias is prepared. The load-bearing and high-temperature resistant substrate is divided into two parts, the upper part is the microstrip line substrate, and the lower part is the feed network substrate; Through the selective laser activation process, a slotted metal microstrip is prepared on the top of the microstrip line substrate, a metal ground shielding layer is prepared on the top of the feed network substrate, and a feed network structure is prepared on the bottom; The preparation of the integrated radiation and stealth metasurface antenna is completed by connecting the slotted metal microstrip and the feeding network structure with the vertical through-hole equal-diameter conductor; Fill each joint with high temperature resistant inorganic glue and dry it; wherein, the high temperature resistant inorganic glue includes silicone glue, silicate glue and aluminate glue, and the use temperature is not less than 300°C.

10. The method for manufacturing a high-speed aircraft skin structure according to claim 9, characterized in that: The laser etching process is used to optimize the accuracy of the vertical vias of the load-bearing and high-temperature resistant substrate, so that the via accuracy is better than 0.1mm'.

Images