A composite structure integrating stealth and electric heating

Abstract

This invention belongs to the field of electronic functional materials technology, specifically relating to an integrated stealth and electrothermal composite structure. It includes, from bottom to top, a conductive reflective layer, an insulating layer, a resistance wire and a wave-transparent dielectric puncture composite layer, and a surface wave-transparent layer. The resistance wire and wave-transparent dielectric puncture composite layer is an M×M array structure composed of alternating coded structural units I and II. Coded structural unit I is a square array structure composed of multiple resistance wires I arranged parallel to each other on the surface of the wave-transparent dielectric, and coded structural unit II is a square array structure composed of multiple resistance wires II arranged parallel to each other on the surface of the wave-transparent dielectric. Resistance wires I and II are perpendicular. M is an even number. Coded structural units I and II have the same size and equal number. Resistance wires I and II have the same size. This invention has a simple structure, is compatible with conventional composite material structures, and solves the problem of integrating stealth and electrothermal functions.

Description

Technical Field

[0001] This invention belongs to the field of electronic functional materials technology, specifically relating to a composite structure integrating stealth and electric heating. Background Technology

[0002] Currently, radar stealth materials have been widely used, playing a crucial role in enhancing the battlefield survivability of equipment. Among them, stealth materials with excellent performance can be obtained by utilizing the designability and frequency selectivity of artificial structural units. For example, patents CN201110052236.6, CN201610837738.2, CN201610330732.6, CN201610479707.4, CN201310078127.0, and CN111585041A disclose several stealth materials designed based on artificial electromagnetic materials.

[0003] For certain specialized parts of equipment, such as aircraft wings, icing can compromise aircraft safety and stability, and these areas also require stealth treatment. Therefore, achieving anti-icing / de-icing capabilities while maintaining stealth performance has significant practical value. While electric heating can be used for de-icing, electric heating and stealth performance often conflict because current stealth design principles primarily rely on two approaches: wave absorption and wave scattering. To achieve electric heating, a conductor must be used in the circuit design before heating. However, continuous conductors strongly reflect incident electromagnetic waves, causing the structure to lose its wave absorption properties. Therefore, reconciling these two aspects has become a key research challenge. Summary of the Invention

[0004] To address the incompatibility between stealth and electric heating functions, this invention provides an integrated composite structure for stealth and electric heating. This structure consists of a conductive reflective layer, an insulating layer, a resistance wire and a wave-transparent dielectric puncture composite layer, and a surface wave-transparent layer. It has advantages such as simple structure, mature manufacturing process, and low cost.

[0005] The present invention is specifically implemented through the following technical solution.

[0006] A stealth and electric heating integrated composite structure includes, from bottom to top, a conductive reflective layer, an insulating layer, a resistance wire and a wave-transparent medium puncture composite layer, and a surface wave-transparent layer;

[0007] The resistance wire and the wave-transparent medium puncture composite layer is an M×M array structure composed of alternating coded structural units I and coded structural units II; the coded structural unit I is a square array structure composed of multiple resistance wires I arranged in parallel on the surface of the wave-transparent medium, and the coded structural unit II is a square array structure composed of multiple resistance wires II arranged in parallel on the surface of the wave-transparent medium; the resistance wires I and II are perpendicular.

[0008] Where M is an even number; the coding structure unit I and the coding structure unit II have the same size and the same number; the resistance filament I and the resistance filament II have the same size.

[0009] Furthermore, the lengths of resistance filament I and resistance filament II are 10–50 mm, respectively.

[0010] Furthermore, the gap between two adjacent resistive filaments I is equal, ranging from 1 to 5 mm;

[0011] Furthermore, the gap between two adjacent resistive filaments II is equal, ranging from 1 to 5 mm.

[0012] Furthermore, the side lengths of coding structure unit I and coding structure unit II are 10~50mm.

[0013] Furthermore, the conductivity of both resistance filament I and resistance filament II is 10. 3 ~10 6 S / m.

[0014] Furthermore, the dielectric constant of the wave-transmitting medium is 1~6, and the dielectric loss angle is 0.001~0.05.

[0015] Furthermore, the materials of resistance filament I and resistance filament II include iron-chromium-nickel resistance wire and continuous carbon fiber.

[0016] Furthermore, the wave-transparent medium includes foam, honeycomb, and wave-transparent fiber-reinforced composite materials.

[0017] Furthermore, the relative permittivity of the surface wave-transparent layer ranges from 2.2 to 6, and the dielectric loss angle is from 0.001 to 0.05.

[0018] Furthermore, the surface wave-transparent layer includes glass fiber, quartz fiber, and aramid fiber.

[0019] Furthermore, the conductive reflective layer is located at the bottom layer and is made of carbon fiber plate or metal. A glass fiber cloth is bonded to it with epoxy resin as an insulating layer. The main function of the insulating layer is to isolate the conductive reflective layer from the resistance wire and the wave-transmitting medium piercing composite layer to prevent short circuits.

[0020] The principle of this invention is as follows:

[0021] There are two main principles behind current stealth design: absorption and scattering. Since the structure needs to achieve electric heating, a conductor is used in the circuit design before heating (e.g., using alloy resistance wire). Continuous conductors strongly reflect incident electromagnetic waves, causing the structure to lose its absorption performance. Based on this, we use the principle of phase cancellation scattering for stealth structure design. The structure of this invention is a checkerboard-shaped metasurface with scattering capabilities. The basic principle is as follows: the electromagnetic properties of the coded metasurface can be changed by different coding sequences of the coding units, thereby achieving different functions. The checkerboard-shaped coded metasurface is composed of two basic coding units, "0" and "1". The two units have a scattering phase difference of approximately 180° within a certain frequency band. Since the scattered fields of the two units are out of phase, arranging these two basic units in a certain sequence in a two-dimensional space to form a macroscopic structure can cancel out the generated scattered fields. By adjusting the arrangement sequence of the two units, different far-field scattering characteristics can be obtained. The 0 unit and the 1 unit have a scattering phase difference of approximately 180 degrees within a wide frequency band, thus achieving cancellation of the scattered waves. Furthermore, by designing the spatial coding arrangement of 0 and 1 elements, the scattered waves of electromagnetic waves incident on the surface are made to form as many beams as possible. According to the law of energy conservation, the scattered energy of each beam is very low, thereby reducing the radar cross section (RCS). Based on this principle, this design can be successfully completed.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention solves the design problem of integrating stealth and electric heating. It achieves stealth performance through the principle of electromagnetic scattering, while the electric heating function has anti-icing and de-icing effects. Specifically, when this invention is applied to a structure that requires integrated stealth and electric heating (such as an aircraft wing), electromagnetic waves emitted by an enemy radar will scatter when they hit the surface of this structure, thereby reducing the radar cross section (RCS) of the overall structure and achieving stealth. At the same time, when the aircraft is operating in a harsh environment with high altitude and low temperature and the fuselage is covered with a thin layer of ice, this invention can be electrically heated. The higher the power, the faster the temperature rises, and the longer the heating time, the higher the temperature, without affecting the stealth effect of the structure. Thus, the invention achieves a compatible effect of stealth and electric heating de-icing.

[0024] 2. This invention has the advantages of simple structure, mature preparation process and low cost.

[0025] 3. The stealth and electric heating integrated composite structure provided by this invention has a wide range of applicable materials, which is beneficial for its application in various working conditions and environments. Attached Figure Description

[0026] Figure 1 A schematic diagram of the integrated stealth and electric heating composite structure provided by the present invention;

[0027] (a) is a schematic diagram of the longitudinal structure of the composite structure; (b) is a schematic diagram of the resistance wire and the wave-transmitting medium puncture composite layer in (a).

[0028] Figure 2 This is a photograph of the puncture composite layer of resistance wire and wave-transmitting medium in Embodiment 1 of the present invention.

[0029] Figure 3 The simulation and test reflectivity curves of the stealth and electric heating integrated composite structure of Embodiment 1 of the present invention are shown.

[0030] Figure 4 This is the temperature change curve over time during heating in Embodiment 1 of the present invention.

[0031] Figure 5 This is an infrared photograph of ice melting by electric heating, according to Embodiment 1 of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Conductive reflective layer; 2. Insulating layer; 3. Resistance wire and wave-transmitting medium puncture composite layer; 4. Surface wave-transmitting layer; 31. Encoding structure unit I; 32. Encoding structure unit II; 11. Resistance wire I; 22. Resistance wire II. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0035] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0036] The concept of this invention is as follows:

[0037] When icing occurs at the application sites of stealth materials, it can pose a safety hazard to aircraft. Therefore, stealth materials need to also have de-icing capabilities. While electric heating can be used for de-icing, electric heating and stealth performance are often mutually restrictive. This is because current stealth designs primarily operate on two principles: absorption and scattering. To achieve electric heating, a conductor is used in the circuit design before heating. However, continuous conductors strongly reflect incident electromagnetic waves, causing the structure to lose its absorption properties. To address this, this application provides an integrated stealth and electric heating composite structure, including a checkerboard-shaped coded metasurface. This metasurface is formed by piercing resistance wires in a wave-transparent medium and comprises two units (coded structural unit I and coded structural unit II). The two units scatter with a phase difference of approximately 180° within a certain frequency band. Since the scattered fields of the two units are out of phase, arranging these two basic units sequentially in a two-dimensional space to form a macroscopic structure can cancel out the generated scattered fields. By adjusting the arrangement sequence of the two types of units, different far-field scattering characteristics can be obtained. The scattering phase difference between the 0-unit and 1-unit is approximately 180 degrees over a wide frequency band, thus achieving cancellation of the scattered waves. This not only gives the material stealth capabilities but also enables de-icing via electric heating.

[0038] The invention will now be described in detail through the following embodiments.

[0039] Example 1

[0040] A composite structure integrating stealth and electric heating, such as Figure 1 As shown, starting from the conductive reflective layer 1 and the insulating layer 2 (the conductive reflective layer 1 is a carbon fiber sheet, and the insulating layer 2 is a glass fiber cloth), from bottom to top, it includes a resistance wire and a wave-transmitting medium puncture composite layer 3 and a surface wave-transmitting layer 4 (glass fiber reinforced epoxy resin composite material). The thicknesses of the carbon fiber sheet (conductive reflective layer 1) and the glass fiber cloth (insulating layer 2) are 0.2 mm and 0.17 mm, respectively. The thickness of the resistance wire and wave-transmitting medium puncture composite layer 3 is 5.3 mm, wherein the resistance wire is an iron-chromium-nickel alloy resistance wire with a conductivity of 9.2 × 10⁻⁶. 5 The dielectric constant (S / m) is 1.08, and the dielectric material is polymethacrylimide (PMI) foam with a relative permittivity of 1.08 and a thickness of 5.2 mm. The FR-4 surface dielectric layer has a relative permittivity of 4.3, a dielectric loss angle of 0.025°, and a thickness of 1.2 mm. The resistance wire and dielectric material puncture composite layer 3 consists of coded structural units I 31 and II 32 arranged in a checkerboard pattern in a 4×4 array structure; both coded structural units I 31 and II 32 are 45 mm × 45 mm in size.

[0041] like Figure 2As shown, the coding structure unit I 31 is a square array structure composed of multiple resistor filaments I 11 arranged horizontally in parallel on the surface of the wave-transparent medium, and the coding structure unit II 32 is a square array structure composed of multiple resistor filaments II 22 arranged vertically in parallel on the surface of the wave-transparent medium. The length of resistor filaments I 11 and II 22 is 45 mm. The gap between two adjacent resistor filaments I 11 is equal, which is 4.3 mm; the gap between two adjacent resistor filaments II 22 is equal, which is 4.3 mm.

[0042] Based on the above design parameters, a stealth and electrothermal integrated composite structure was fabricated using puncture and vacuum-assisted processes (e.g., Figure 2 The image shown is a photograph of the prepared resistance wire and wave-transmitting dielectric puncture composite layer.

[0043] Simulated and tested reflectivity curves are as follows Figure 3 As shown, the reflectivity is less than -10dB in most of the 8–18 GHz frequency band, exhibiting broadband radar stealth performance. The heating efficiency of the integrated electric heating and stealth composite structure under different voltages and currents, measured using thermocouples, is shown below. Figure 4 As shown. Under conditions of 10.3V and 1.51A, the composite structure can be heated from room temperature 23.5℃ to 38.1℃ after 800s of heating; under conditions of 13.8V and 2.01A, the composite structure can be heated from room temperature 23.5℃ to 52.3℃ after 800s of heating; under conditions of 20.5V and 3.01A, the composite structure can be heated from room temperature 23.5℃ to 71.0℃ after less than 400s of heating. Figure 5 The composite structure was shown to be electrically heated and de-iced at 13.8V and 2.01A, and the results showed that the de-icing effect was good. Therefore, this invention exhibits excellent integrated performance in both electric heating and stealth.

[0044] This is because in this embodiment, coding structure unit I and coding structure unit II are arranged in a 4×4 array structure in a checkerboard pattern. The checkerboard-shaped coding metasurface is composed of two basic coding units, "0" and "1". The two units have a scattering phase difference of approximately 180° within a certain frequency band. Since the scattered fields of the two units are out of phase, arranging the two basic units in a certain sequence in a two-dimensional spatial direction to form a macroscopic structure can cancel out the generated scattered fields. Furthermore, by designing the spatial coding arrangement of 0 and 1 units, the scattered waves of electromagnetic waves incident on this surface can form as many beams as possible. According to the law of energy conservation, the scattered energy of each beam is very low, thereby reducing the radar cross section (RCS). This allows the present invention to have both stealth capabilities and de-icing capabilities through electric heating, solving the current problem of incompatibility between stealth and electric heating functions.

[0045] Example 2

[0046] A stealth and electrically heated integrated composite structure, starting from a conductive reflective layer 1 and an insulating layer 2 (the conductive reflective layer 1 is metal, and the insulating layer 2 is fiberglass cloth), sequentially includes, from bottom to top, a resistance wire and a wave-transparent medium puncture composite layer 3, and a surface wave-transparent layer 4 (quartz fiber reinforced epoxy resin composite material). The wave-transparent medium is polyvinyl chloride (PVC). The thicknesses of the conductive reflective layer 1 and the insulating layer 2 are 0.035 mm and 0.1 mm, respectively. The thickness of the resistance wire and wave-transparent medium puncture composite layer 3 is 6.2 mm. The resistance wire is an iron-chromium-nickel alloy resistance wire with a conductivity of 9.2 × 10⁻⁶. 5 The relative permittivity of the surface wave-transparent layer 4 of the quartz fiber reinforced epoxy resin composite material is 3.3, the dielectric loss angle is 0.005, and the thickness is 1.5 mm. The resistance wire and wave-transparent dielectric piercing composite layer 3 is composed of coded structural unit I 31 and coded structural unit II 32 arranged in a checkerboard pattern in a 6×6 array structure; the size of coded structural unit I and coded structural unit II is 40 mm × 40 mm.

[0047] Encoding structure unit I 31 is a square array structure composed of multiple resistor filaments I 11 arranged horizontally in parallel on the surface of the wave-transparent medium. Encoding structure unit II 32 is a square array structure composed of multiple resistor filaments II 22 arranged vertically in parallel on the surface of the wave-transparent medium. The length of resistor filaments I 11 and II 22 is 40 mm. The gap between two adjacent resistor filaments I 11 is equal, which is 3.7 mm; the gap between two adjacent resistor filaments II 22 is equal, which is 3.7 mm.

[0048] According to the above design parameters, a stealth and electro-heating integrated composite structure was fabricated using a puncture process and a vacuum-assisted process. The results show that the reflectivity is less than -10 dB in the 6–18 GHz range, and under conditions of 20 V and 2.2 A, the composite structure can be heated from room temperature (23.5 °C) to above 50 °C after 800 s of heating. Similarly, Example 2 demonstrates that the present invention possesses excellent electro-heating and stealth integration performance.

[0049] Example 3

[0050] A stealth and electric heating integrated composite structure, starting from a conductive reflective layer 1 and an insulating layer 2 (the conductive reflective layer is metal, and the insulating layer is fiberglass cloth), sequentially includes, from bottom to top, a resistance wire and wave-transparent medium puncture composite layer 3, and a surface wave-transparent layer 4 (quartz fiber reinforced epoxy resin composite material). The wave-transparent medium is polyvinyl chloride (PVC). The thicknesses of the conductive reflective layer 1 and the insulating layer 2 are 0.035 mm and 0.1 mm, respectively, and the thickness of the resistance wire and wave-transparent medium puncture composite layer 3 is 6.2 mm. The conductivity of the iron-chromium-nickel alloy resistance wire is 9.2 × 10⁻⁶.5 The relative permittivity of the surface wave-transparent layer 4 of the quartz fiber reinforced epoxy resin composite material is 3.3, the dielectric loss angle is 0.005, and the thickness is 1.5 mm. The resistance wire and wave-transparent dielectric piercing composite layer 3 is composed of coded structural unit I 31 and coded structural unit II 32 arranged in a checkerboard pattern in a 6×6 array structure; the size of coded structural unit I 31 and coded structural unit II 32 is 50 mm × 50 mm.

[0051] Encoding structure unit I 31 is a square array structure composed of multiple resistor filaments I 11 arranged horizontally in parallel on the surface of the wave-transparent medium. Encoding structure unit II 32 is a square array structure composed of multiple resistor filaments II 22 arranged vertically in parallel on the surface of the wave-transparent medium. The length of resistor filaments I 11 and II 22 is 50 mm. The gap between two adjacent resistor filaments I 11 is equal, which is 1 mm; the gap between two adjacent resistor filaments II 22 is equal, which is 1 mm.

[0052] Example 4

[0053] A stealth and electric heating integrated composite structure, starting from a conductive reflective layer 1 and an insulating layer 2 (the conductive reflective layer is metal, and the insulating layer is fiberglass cloth), sequentially includes, from bottom to top, a resistance wire and wave-transparent medium puncture composite layer 3, and a surface wave-transparent layer 4 (quartz fiber reinforced epoxy resin composite material). The wave-transparent medium is polyvinyl chloride (PVC). The thicknesses of the conductive reflective layer 1 and the insulating layer 2 are 0.035 mm and 0.1 mm, respectively, and the thickness of the resistance wire and wave-transparent medium puncture composite layer 3 is 6.2 mm. The conductivity of the iron-chromium-nickel alloy resistance wire is 9.2 × 10⁻⁶. 5 The surface wave-transparent layer 4 of the quartz fiber reinforced epoxy resin composite material has a relative permittivity of 3.3, a dielectric loss angle of 0.005, and a thickness of 1.5 mm. The resistance wire and wave-transparent dielectric piercing composite layer 3 consists of coded structural units I 31 and coded structural units II 32 arranged in a checkerboard pattern in a 6×6 array structure; the size of coded structural units I and II is 10 mm × 10 mm.

[0054] Encoding structure unit I 31 is a square array structure composed of multiple resistor filaments I 11 arranged horizontally in parallel on the surface of the wave-transparent medium. Encoding structure unit II 32 is a square array structure composed of multiple resistor filaments II 22 arranged vertically in parallel on the surface of the wave-transparent medium. The length of resistor filaments I 11 and II 22 is 10 mm. The gap between two adjacent resistor filaments I 11 is equal, which is 1 mm; the gap between two adjacent resistor filaments II 22 is equal, which is 1 mm.

[0055] Example 5

[0056] A stealth and electric heating integrated composite structure, starting from a conductive reflective layer 1 and an insulating layer 2 (the conductive reflective layer is metal, and the insulating layer is fiberglass cloth), sequentially includes, from bottom to top, a resistance wire and wave-transparent medium puncture composite layer 3, and a surface wave-transparent layer 4 (quartz fiber reinforced epoxy resin composite material). The wave-transparent medium is polyvinyl chloride (PVC). The thicknesses of the conductive reflective layer 1 and the insulating layer 2 are 0.035 mm and 0.1 mm, respectively, and the thickness of the resistance wire and wave-transparent medium puncture composite layer 3 is 6.2 mm. The conductivity of the iron-chromium-nickel alloy resistance wire is 9.2 × 10⁻⁶. 5 The surface wave-transparent layer 4 of the quartz fiber reinforced epoxy resin composite material has a relative permittivity of 3.3, a dielectric loss angle of 0.005, and a thickness of 1.5 mm. The resistance wire and wave-transparent dielectric piercing composite layer 3 consists of coded structural units I 31 and II 32 arranged in a checkerboard pattern in a 6×6 array structure; the size of both coded structural units I 31 and II 32 is 50 mm × 50 mm.

[0057] Encoding structure unit I 31 is a square array structure composed of multiple resistor filaments I 11 arranged horizontally in parallel on the surface of the wave-transparent medium. Encoding structure unit II 32 is a square array structure composed of multiple resistor filaments II 22 arranged vertically in parallel on the surface of the wave-transparent medium. The length of resistor filaments I 11 and II 22 is 50 mm. The gap between two adjacent resistor filaments I 11 is equal, which is 5 mm; the gap between two adjacent resistor filaments II 22 is equal, which is 5 mm.

[0058] Similar to Example 1, the structures prepared in Examples 3-5 also achieved integrated electroheating and stealth performance, and the specific results will not be repeated here.

[0059] It should be understood that the material of the above-described composite structure is merely one embodiment of the present invention, and the specific choice should be determined according to the actual situation. The present invention does not impose any limitations on this. It should also be understood that the above-described structural dimensions are merely one embodiment, provided as an example, and the specific dimensional variations should be determined according to the actual situation. The present invention does not impose any limitations on this.

[0060] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A stealth and electric heating integrated composite structure, characterized in that, The conductive reflecting layer (1), the insulating layer (2), the resistance wire and the wave-penetrating medium piercing composite layer (3) and the surface wave-penetrating layer (4) are sequentially arranged from bottom to top. The resistance wire and the wave-penetrating medium piercing composite layer (3) are an MxM array structure formed by interleaving coding structure unit I (31) and coding structure unit II (32); the coding structure unit I (31) is a square array structure formed by parallel arrangement of a plurality of resistance filaments I (11) on the surface of the wave-penetrating medium; the coding structure unit II (32) is a square array structure formed by parallel arrangement of a plurality of resistance filaments II (22) on the surface of the wave-penetrating medium; the resistance filaments I (11) and the resistance filaments II (22) are perpendicular. Wherein, M is an even number; the coding structure unit I (31) and the coding structure unit II (32) have the same size and equal number; the resistance filaments I (11) and the resistance filaments II (22) have the same size.

2. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The length of the resistance filaments I (11) and the resistance filaments II (22) is 10-50 mm.

3. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The length of the resistance filaments I (11) and the resistance filaments II (22) is 10-50 mm.

4. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The gap between the two adjacent resistance filaments I (11) is equal, and is 1-5 mm. The gap between the two adjacent resistance filaments II (22) is equal, and is 1-5 mm.

5. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The electrical conductivity of the resistance filament I (11) and the resistance filament II (22) is 10 3 ~ 10 6 S / m.

6. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The resistance filaments I (11) and the resistance filaments II (22) are made of iron-chromium-nickel resistance wire or continuous carbon fiber.

7. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The dielectric constant of the wave-penetrating medium is 1-6, and the dielectric loss angle is 0.001-0.

05. The wave-penetrating medium is foam, honeycomb or wave-penetrating fiber reinforced composite material.

8. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The relative dielectric constant of the surface wave-penetrating layer (4) is 2.2-6, and the dielectric loss angle is 0.001-0.

05. The surface wave-penetrating layer (4) is made of glass fiber, quartz fiber or aramid fiber.

9. The integrated stealth and electrically-heated composite structure of claim 1, wherein, The conductive reflecting layer (1) is carbon fiber plate or metal, and the insulating layer (2) is glass fiber cloth.

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