A design method of temperature adaptive infrared / radar compatible cloaking surface structure

Abstract

The application relates to a design method of a temperature self-adaptive infrared / radar compatible stealth surface structure, belonging to the field of aerospace infrared and radar stealth. The temperature self-adaptive infrared / radar compatible stealth surface structure is a layered structure, comprising a radar wave absorbing layer, a heat insulation layer and a temperature self-adaptive infrared emission layer. The radar wave absorbing layer can absorb waves by more than 10 dB in a 4-12 GHz frequency band, and can realize radar stealth. The heat insulation layer adopts a micro-nano heat insulation film to isolate an internal heat source of the target. The temperature self-adaptive infrared emission layer can change the emissivity range to 0.23-0.88 in an atmospheric window (8-12 mu m) wave band, and can realize heat management and infrared stealth of the target. Through the innovative design of the multilayer micro-nano structure and the excellent electromagnetic regulation and control performance of the graphene composite material, the bottleneck problem that the regulation and control of the radar characteristics and the regulation and control of the infrared characteristics are restricted by each other is avoided, and the maximum efficiency of the comprehensive regulation and control of the radar and infrared characteristics is realized.

Description

Technical Field

[0001] This invention relates to the field of aerospace infrared and radar stealth, specifically to a temperature-adaptive infrared / radar compatible stealth multilayer surface thin film structure. Background Technology

[0002] With the development of high technology and social progress, the new generation of space situational awareness systems has broad application prospects. The mature application of current space situational awareness systems has enabled integrated radar and infrared space situational awareness capabilities globally, providing accurate detection and early warning functions across all time periods and the entire spectrum for fields such as civil aviation and weather forecasting. However, in current emergency response technologies, there are mutual constraints and balance issues among detection, privacy protection, and defense functions, requiring a unified and coordinated solution. Therefore, achieving integrated functions such as intelligent detection, privacy protection, and defense will be an important issue in the future security field. Security systems in various countries are increasingly emphasizing the acquisition and counter-acquisition of multi-dimensional information, which plays a crucial role in modern security. The development and application of low-observable technologies are inevitable. By reducing the characteristic signal characteristics of targets, making them difficult for others to detect, identify, track, locate, and attack, the goal of protecting one's own security is achieved. Modern low-observable technologies include electronic radar, infrared sensing, electromagnetic monitoring, visible light stealth, sonar technology, and multi-band technology fusion. Currently, security systems mainly face threats from radar detection and infrared detection.

[0003] While numerous studies have focused on achieving target stealth through infrared signature modulation, radar signature modulation, and integrated radar-infrared signature modulation, yielding significant progress and breakthroughs, the use of radar absorbing materials in practical applications often generates excessive heat, thus affecting the effectiveness of infrared signature modulation. Therefore, further solutions are needed to maximize the effectiveness of integrated radar-infrared signature modulation and avoid the mutual constraints between radar signature modulation and infrared signature modulation. Summary of the Invention

[0004] To address the bottleneck issue of mutual constraints between radar and infrared signature modulation, this patent proposes a temperature-adaptive infrared / radar-compatible stealth surface structure. This surface structure can achieve both radar stealth and infrared signature modulation. Through the design and organic combination of multi-layer film structures, it achieves stealth compatibility across multiple spectral ranges, including long-wave infrared and radar. Simultaneously, it can adaptively adjust its emissivity according to changes in target temperature and, combined with a micro / nano-structured thermal insulation film, achieve thermal management of the target.

[0005] A temperature-adaptive infrared / radar-compatible stealth surface structure is a layered structure with a square top view, comprising the following functional areas:

[0006] Infrared modulation functional region: graphene-doped infrared radiation modulation film

[0007] Insulation zone: Micro-nano structured insulation membrane

[0008] Radar absorbing functional area: Multi-layer graded thin film for radar absorbing

[0009] Furthermore, the infrared modulation functional region has a layered structure, composed of three layers of materials, from bottom to top: graphene, zinc sulfide (ZnS), and vanadium dioxide (VO2). The thicknesses of each layer are 0.5 μm, 0.75 μm, and 0.075 μm, respectively.

[0010] When the target is at a high temperature (above the phase transition temperature of VO2), VO2 is in a low-resistivity (metallic) state. At this temperature, the thinner VO2 layer has high transmittance for infrared radiation, with most infrared radiation passing through the VO2 layer into the lower layers of the film. By introducing an infrared-transmitting ZnS film layer between the bottom graphene layer and the VO2 film, a Fabry-Perot (FP) resonant microcavity structure can be obtained. Utilizing the principle of destructive interference, the infrared absorption rate of the surface structure can be significantly improved. This achieves high emissivity on the target surface at high temperatures, enabling rapid infrared heat dissipation. Combined with an adiabatic zone, the surface film can be quickly cooled to its equilibrium temperature. When the target is at a low temperature (below the phase transition temperature of VO2), VO2 is in a high-resistivity (insulating) state. At this temperature, VO2 has high reflectivity for infrared radiation, maintaining low infrared absorption and emissivity on the device surface. The infrared modulation functional area has temperature-adaptive surface emissivity control capabilities. Combined with an adiabatic zone, temperature-adaptive target thermal management can be achieved for rapid high-temperature heat dissipation and low-temperature infrared stealth.

[0011] Furthermore, it consists of a polyester substrate coated with polyurethane acrylate (PUA) material, with a thickness of approximately 0.65 mm and a thermal conductivity of approximately 0.00824 W / m·K.

[0012] Furthermore, the radar absorbing functional area is a periodic structure of a carbon-based impedance-matching graded multilayer film. The periodic unit material is PMI / PET / sheet resistance film, with a total of 5 periods. In addition, a metal grounding layer is located below the periodic unit material. The sheet resistance value of the resistive film is different in each period, and the resistance value decreases from top to bottom.

[0013] Temperature-adaptive infrared / radar-compatible stealth surface structure makes full use of the differences in wavelengths of various electromagnetic waves that require stealth function. (1) The infrared modulation functional area is placed on the upper layer so that it can give full play to the advantages of surface infrared radiation heat transfer, while cooperating with the middle insulation area to perform thermal management of the target; (2) The bottom of the entire layered structure corresponds to the radar absorbing functional area with the longest wavelength. Since the upper structure is all microwave transparent material, the microwave response of the entire layered structure depends almost entirely on the characteristics of the impedance matching radar absorbing multilayer gradient film of the bottom layer, realizing radar stealth and infrared feature modulation within a single surface structure.

[0014] The present invention has the following advantages and benefits:

[0015] A. This invention combines a temperature-adaptive infrared control film based on VO2 with an impedance-matched gradient radar absorbing film, which can achieve radar stealth and infrared feature control in a single surface structure.

[0016] B. This invention utilizes the temperature-dependent phase transition characteristics of VO2 to achieve temperature-adaptive emissivity control of surface devices. It achieves a transition of 0.23 to 0.88 in the emissivity of the atmospheric window (8-12μm) band under high / low temperature conditions, realizing dynamic infrared feature control for high-temperature heat dissipation and low-temperature infrared stealth.

[0017] C. Based on a multilayer resistive film-dielectric composite structure, this invention designs an impedance-matching multilayer gradient thin film material absorber that absorbs more than 10dB of waves in the 4-12GHz frequency band, enabling radar stealth.

[0018] D. This invention utilizes a micro-nano structured heat insulation film to isolate the internal radar-absorbing heat source from the external infrared radiation layer, reduce the heat capacity of the outer surface, and shorten the cooling time of the outer surface, enabling the target to quickly achieve infrared stealth from its initial high-temperature state. Attached Figure Description

[0019] Figure 1 Schematic diagram of radar infrared integrated feature modulation structure

[0020] Figure 2 Schematic diagram of the infrared control functional area

[0021] Figure 3 Simulation results of the emissivity of the infrared modulated functional region under high temperature and low temperature conditions.

[0022] Figure 4 Schematic diagram of the insulation zone

[0023] Figure 5 Simulation results of radar absorption in the radar absorption functional area

[0024] Figure 6Simulation results of temperature distribution of radar infrared integrated feature control structure under isothermal heat source. Detailed Implementation

[0025] To clearly illustrate the device design structure and outstanding advantages described in this invention, the invention will be specifically described below with reference to the accompanying drawings and examples. The embodiments described below are only a part of the embodiments of this invention, not all of them.

[0026] The actual structure of the present invention is as follows Figure 1 As shown, a temperature-adaptive infrared / radar-compatible stealth multilayer surface film structure is disclosed. From top to bottom, the structure consists of an infrared radiation modulation film composed of VO2, ZnS, and graphene; a micro-nano structure heat insulation film; and a radar-absorbing multilayer gradient film composed of PMI, PET, a resistive film, and a metal grounding layer.

[0027] Implementation Examples

[0028] In this example, all film layers except the resistive film layer have a side length of 350 mm.

[0029] In this example, the thicknesses of VO2, ZnS, and graphene in the infrared radiation-controlled film are 0.075 μm, 0.75 μm, and 0.5 μm, respectively. The specific structure is as follows: Figure 2 As shown. The infrared emissivity curves of the infrared radiation modulation film at atmospheric windows (8–12 μm) under high and low temperatures, simulated using the finite element method, are shown below. Figure 3 As shown, the average emissivity is 0.88 at high temperature (350K) and 0.23 at low temperature (290K).

[0030] In this invention, the periodic unit material of the radar absorbing multilayer graded thin film is PMI / PET / sheet resist film, with a total of 5 periods. The actual structure is as follows: Figure 4 As shown in the figure, w1 to w5 represent the side length of the resistive film in each cycle, R1 to R5 represent the sheet resistance of the resistive film in each cycle, t1 to t5 represent the thickness of the PMI layer in each cycle, and p is the device side length. The sheet resistance of the resistive film is different in each cycle, decreasing from top to bottom, with R1 to R5 being 550Ω / □, 490Ω / □, 400Ω / □, 320Ω / □, and 260Ω / □, respectively. The resistive film size also varies in each cycle, with w1 to w5 being 255mm, 200mm, 267mm, 258mm, and 300mm, respectively. The PET thickness is the same in each cycle, at 0.3mm. The PMI thickness also varies in each cycle, with t1 to t5 being 6mm, 2mm, 5mm, 3mm, and 2mm, respectively. Furthermore, the metal grounding layer is made of Cu material with a thickness of 0.2mm. The radar absorption characteristics were simulated using the finite element method, and the simulation results are as follows. Figure 5As shown, it absorbs more than 10dB of waves in the 4-12GHz frequency band.

[0031] In this example, the micro / nano structure insulation film uses an insulation material composed of polyurethane acrylate (PUA) and a polyester substrate, with a thickness of approximately 0.65 mm and a thermal conductivity of approximately 0.00824 W / m·K. The temperature distribution of the surface device after 1000 s at a constant temperature heat source boundary of 500 K, simulated using finite element analysis, is as follows: Figure 6 As shown, the surface temperature of the surface structure with the micro-nano structure insulation film is 167K lower than that of the surface structure without the micro-nano structure insulation film.

[0032] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A design method for a temperature-adaptive infrared / radar-compatible stealth surface structure, characterized in that: Its overall structure is layered, with each layer having a square top view, and from top to bottom including the following functional areas: Infrared modulation functional area: It is formed by spraying graphene, zinc sulfide (ZnS) and vanadium dioxide (VO2) materials from bottom to top by magnetron sputtering, wherein the thicknesses of graphene, ZnS and VO2 materials are 0.2~2μm, 0.25~3μm and 0.01~0.2μm, respectively; Insulation zone: Composed of a polyester substrate coated with polyurethane acrylate (PUA) material, the thermal conductivity of the insulation zone is 0.008~0.03 W / m·K, and its thickness is 0.5~5 mm; Radar absorbing functional area: It consists of two parts: a periodic layered material and a metal grounding layer. The periodic layered material has 5 periods, and each periodic unit includes a resistive film layer, a thermoplastic polyester layer and an insulating layer from top to bottom.

2. The design method according to claim 1, characterized in that: The sheet resistance of the resistive film varies in each cycle. The sheet resistance of the top layer in the first cycle is 500~800Ω / □, and the sheet resistance of the resistive film decreases by 50~100Ω / □ in the second, third, fourth and fifth cycles from top to bottom compared with the previous cycle. The side length of the resistive film ranges from 190 to 310mm and the thickness ranges from 1 to 3mm in all cycles.

3. The design method according to claim 1, characterized in that: The thermoplastic polyester layer material is polyethylene terephthalate (PET), with a thickness ranging from 0.1 to 0.5 mm in each cycle.

4. The design method according to claim 1, characterized in that: The insulating layer material is polymethacrylimide foam (PMI); its thickness is 4.5~6.5 mm in the first and third cycles from top to bottom; and 1.5~3.5 mm in the second, fourth, and fifth cycles.

5. The design method according to claim 1, characterized in that: The metal grounding layer is at the bottom, and the material is copper or silver, with a thickness of 0.01~0.5mm.

6. The design method according to claim 1, characterized in that: Except for the resistive film layer, the other film layers have equal side lengths, ranging from 320 to 400 mm.

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