Methods for Selecting Optimal Stealth Coating Materials for Metal Observation Objects in Different Environments

Abstract

The application discloses a method for selecting optimal stealth coating layer materials of metal observation objects in different environments, and comprises the following steps: S1, physically modeling a detected scene; S2, obtaining a three-dimensional dissection model of the detected scene; S3, forming a brightness temperature graph; S4, recording the surface number of the surface needing to be coated with a stealth coating layer; S5, coating the surface found and recorded in step S4 with a stealth coating layer; S6, repeating step S3 and recording the average incident angle of the tracking ray of the surface needing to be coated; S7, assuming the coating layer as an ideal smooth surface and drawing a contour graph; S8, extracting the contour graph drawn in step S7 through software; S9, statistically processing the target radiation cross-sectional area parameters of the coating surface after brightness temperature inversion each time; S10, selecting the dielectric constant of the coating layer of the corresponding grade; S11, comparing with a brightness temperature imaging graph of a metal observation object without a coating medium; and S12, observing and statistically processing the influence of the observation angle of a millimeter wave radiometer on the selection of the stealth coating layer.

Description

Technical Field

[0001] This invention relates to the fields of computer-aided analysis and design and software design, and in particular to a method for selecting the optimal stealth coating material for metallic observation objects under different environments. Background Technology

[0002] Passive millimeter-wave imaging simulation is a crucial component of the field. It helps in understanding the radiation characteristics of targets, interpreting radiation phenomena, identifying radiation patterns, and evaluating the quality of actual measurement results. These advantages have led to its increasing importance in recent years. Currently, most work on radiometer stealth for metallic targets focuses on reducing the target's radiation cross-section. Methods for reducing radiation cross-section include shape stealth, material stealth, passive cancellation, active cancellation, and temperature control. Among these, material stealth is less costly and easier to implement compared to other stealth methods. In modern warfare, the use of millimeter-wave stealth coatings is becoming increasingly widespread. Therefore, a new method for selecting stealth coating materials is needed to quickly and accurately determine the most suitable coating material for different background environments, thereby reducing the selection time and improving the accuracy of coating material selection. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a method for selecting the best stealth coating material for metal observation objects under different environments.

[0004] This invention is achieved through the following technical solution:

[0005] The method for selecting the optimal stealth coating material for metallic observation objects under different environments includes the following steps:

[0006] S1. Perform physical modeling on the scene to be detected to obtain a three-dimensional virtual model of the scene to be detected;

[0007] S2. The three-dimensional virtual model obtained in step S1 is subdivided to obtain a three-dimensional subdivided model of the scene being probed.

[0008] S3. Perform ray tracing on the three-dimensional mesh model obtained in step S2. After the ray tracing is completed, invert the brightness temperature from the end of each ray to the emission source point to obtain the brightness temperature at different locations in the detected scene and form a brightness temperature map.

[0009] S4. Compare and identify the brightness temperature difference between different surfaces of the target metal object and the environmental background, and record the surface numbers that need to be coated with the stealth coating.

[0010] S5. Apply a stealth coating to the surfaces found and recorded in step S4.

[0011] S6. Repeat step S3 and record the average incident angle of the tracking ray on the surface to be coated.

[0012] S7. Assuming the coating layer is an ideal smooth surface, draw a contour map;

[0013] S8. Extract the contour map drawn in step S7 using OriginPro software, and divide the reflectivity level of the coating layer into n levels.

[0014] S9. Substitute the n levels of coating reflectivity extracted in step S8 into the three-dimensional virtual model to be detected, perform n ray tracing and brightness temperature inversion, and statistically analyze the target radiation cross-sectional area parameters of the coating surface after each brightness temperature inversion.

[0015] S10. Plot the target radiation cross-sectional area parameters of the n levels counted in step S9 into a two-dimensional line graph, find the corresponding level of the target cross-sectional area peak value in the graph, and select the dielectric constant of the corresponding level coating layer.

[0016] S11. Input the dielectric constant obtained in step S10 into the three-dimensional virtual model of the scene being detected, and compare it with the brightness temperature imaging map of the uncoated dielectric metal observation object.

[0017] S12. Change the observation angle of the millimeter-wave radiometer, repeat steps S1 to S11, and observe and statistically analyze the influence of the millimeter-wave radiometer observation angle on the selection of the stealth coating.

[0018] As a preferred embodiment of the present invention: In step S7, the average incident angle of the rays on the coated surface is substituted into the reflectivity equation using Fresnel's law of reflection, with the dielectric constant set as the independent variable and the reflectivity set as the dependent variable. A contour plot with reflectivity as the dependent variable and the dielectric constant of the medium as the independent variable is drawn using OriginPro software.

[0019] This invention discloses a method for selecting the optimal stealth coating material for metallic observation objects under different environments, compared with existing technologies:

[0020] This invention determines the parameters of the stealth coating layer most suitable for the given scenario by conducting simulation tests based on known scenario parameters, which significantly reduces the time required to select the parameters of the stealth coating layer and lowers the cost of manpower and resources. Attached Figure Description

[0021] Figure 1 A three-dimensional virtual model of the scene being probed;

[0022] Figure 2 A 3D virtual scene model after 3D partitioning;

[0023] Figure 3 Brightness temperature map of the target metallic object;

[0024] Figure 4 A schematic diagram of the radiometer's observation target;

[0025] Figure 5 The three-dimensional surface plot is shown with the real and imaginary parts of the relative permittivity on the X and Y axes respectively, and the horizontal polarization reflectivity on the Z axis under horizontal polarization.

[0026] Figure 6 The three-dimensional surface plot is shown with the real and imaginary parts of the relative permittivity on the X and Y axes respectively, and the horizontal polarization reflectivity on the Z axis under vertical polarization.

[0027] Figure 7 for Figure 5 The corresponding contour map;

[0028] Figure 8 for Figure 6 The corresponding contour map;

[0029] Figure 9 Line graph showing the stealth effect C at different levels of horizontal polarization;

[0030] Figure 10 Line graph showing the stealth effect C at different levels of vertical polarization;

[0031] Figure 11 This is a brightness temperature diagram after applying a stealth coating under horizontal polarization.

[0032] Figure 12 This is a brightness temperature diagram after applying a stealth coating under vertical polarization.

[0033] Figure 13 Brightness temperature diagram before applying stealth coating under horizontal polarization;

[0034] Figure 14 Brightness temperature diagram before applying stealth coating under vertical polarization;

[0035] Figure 15 This is a brightness temperature diagram after coating with a radar wave layer under horizontal polarization.

[0036] Figure 16 This is a brightness temperature diagram after coating with a radar wave layer under vertical polarization. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0038] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0039] The specific steps for selecting the optimal stealth coating material for metallic observation objects under different environments are as follows:

[0040] S1. Perform physical modeling on the scene to be detected to obtain a 3D virtual model of the scene. (See attached document) Figure 1 As shown;

[0041] S2. The 3D virtual model obtained in step S1 is subdivided to obtain a 3D subdivided model of the scene being probed. (See reference...) Figure 2 As shown; in Figure 2 In this simulation, a radiometer detects ground targets from the air, with a field of view encompassing a tetrahedron. The simulated background is soil, and a hexahedron of metallic dielectric is placed on top of the soil background. The soil dielectric constant is ε from 1 GHz to 100 GHz. Soil The coordinates of the radiometer antenna in the figure are (x... Top ,y Top ,z Top The center direction of its detection is (θ=θ Middle ,φ=φ Middle The amplitude of the radiometer is Δθ at the azimuth angle and Δθ at the elevation angle. The physical temperature of the ground is set to T. d The physical temperature of the background air is T. Sky The temperature of the hexahedron is T. Object The simulation background is assumed to be a Gaussian rough surface, whose roughness parameters are characterized by the correlation length l and the root mean square height σ. The soil parameters are set as follows (σ = σ). Soil ·λ,φ=φ Soil ·λ);

[0042] S3. Perform ray tracing on the 3D meshed model obtained in step S2. After the ray tracing is completed, invert the brightness temperature from the end of each ray to the emission source point to obtain the brightness temperature at different locations in the detected scene, generating a brightness temperature map, such as... Figure 3 As shown;

[0043] S4. Compare and identify the brightness temperature difference between different surfaces of the target metal object and the environmental background, and record the surface numbers that need to be coated with the stealth coating.

[0044] S5. Apply a stealth coating to the surfaces identified and recorded in step S4. (See attached image) Figure 3As can be seen, the black part in the figure represents the top surface of the metal hexahedron, the white part represents the environment, and the gray part represents the side surface of the metal medium hexahedron. The brightness temperature of the top of the metal target is significantly lower than that of the environment, while the brightness temperature of its side surface is close to that of the environment. Therefore, the top surface of the metal block (i.e. the top surface of the metal medium hexahedron) is taken as the surface that needs to be coated with the stealth coating.

[0045] The millimeter-wave radiation contrast between the target and the background, as well as the stealth effect of the stealth material, can be expressed as Equation (1), defining the radiometer radiation cross section (RRCS) of the target:

[0046] σ' T =A T ΔT T Equation (1);

[0047] In equation (1) σ′ T The unit is m 2 The larger K and RRCS are, the greater the difference between the target and background radiation and the stronger the contrast; A T Let ΔT be the projected area of ​​the target in the beam direction. T The millimeter-wave brightness temperature difference between the target and the background, also known as the target-background contrast, is defined as shown in equation (2). See the schematic diagram of the target observed by the radiometer. Figure 4 As shown:

[0048] ΔT T =|T G -T T |Equation (2);

[0049] In equation (2), T G T is the brightness temperature of the background target. T Target brightness temperature.

[0050] Because ground military targets are generally three-dimensional, their surface brightness temperature is usually unevenly distributed. The surface of a three-dimensional target can be divided into n micro-areas, and the projected area of ​​a single micro-area plane in the beam direction is A. Ti The brightness temperature difference between the background and the background is ΔT Ti By adding up the radiation cross-sectional areas of the small plane elements, we can obtain the total millimeter-wave radiometer radiation cross-sectional area (RRCS) of the entire three-dimensional target, as shown in equation (3):

[0051]

[0052] Both the radiation simulation image and the scanned image of a three-dimensional target are composed of individual pixels. Let the total area of ​​a simulation image or an image be A. Total The total number of pixels is N, and the target area is A. TThere are n target numerical points, and ΔA is the area represented by a unit pixel, as shown in equation (4):

[0053]

[0054] In equation (4), A represents the area represented by a unit numerical point.

[0055] ΔT Ti =|T Gi -T Ti |Equation (5);

[0056] In equation (5), ΔT Ti Let ΔT be the brightness temperature difference between each pixel in the target area and the background. Ti ·ΔA is the RRCS of each unit region. The RRCS of a target consisting of n pixels is shown in equation (6):

[0057]

[0058] S6. Repeat step S3 to screen all the tracking rays whose first incident surface is the surface to be coated. Substitute the brightness temperature data after the screening rays are inverted into equation (3) to generate the RRCS value of the metal surface before coating.

[0059] S6. Repeat step S3 and record the average incident angle Δθ of the tracking ray on the surface to be coated. i .

[0060] S7. Treat the coating layer as a smooth plane (ideal smooth surface). The reflection of a smooth plane is only coherent reflection. Use Fresnel's law of reflection to calculate the reflectivity of the coating surface. Its reflectivity is shown in equations (7) and (8). The average incident angle Δθ is then used. i Substituting into equations (7) and (8), we establish the equation for reflectivity with respect to the relative permittivity of the medium at a fixed incident angle:

[0061]

[0062]

[0063] Equations (7) and (8) represent the reflectivity of horizontal and vertical polarization in the direction of the tracing ray, respectively, where θ is the incident angle of the tracing ray and ε r To track the relative permittivity of the incident medium surface.

[0064] Use Matlab to plot equations (7) and (8) as three-dimensional surface plots, see [reference]. Figure 5 and Figure 6 As shown, the real and imaginary parts of the relative permittivity of the selected coating medium correspond to the X and Y axes of the three-dimensional surface plot, respectively, and the corresponding reflectivity corresponds to the Z axis.

[0065] S8. Use OriginPro software to extract contour plots from the matrix generated by Matlab. (See below) Figure 7 and Figure 8 As shown, where Figure 7 This is the contour plot of equation (7) under horizontal polarization. Figure 8 The contour map of vertical polarization equation (8) is used, and the reflectivity level of the coating layer is divided into n levels by software.

[0066] S9. Substitute the reflectivity of the n levels under horizontal and vertical polarization in step S8 into the three-dimensional subdivision model in sequence, perform n ray tracing and brightness temperature inversion. After the ray tracing part is completed, invert the brightness temperature from the end of each ray to the emission source point to obtain the brightness temperature at different locations in the detected scene and form a brightness temperature map. Perform a total of n simulation calculations and statistically analyze the RRCS values ​​generated each time.

[0067] S10. Plot the target radiation cross-sectional area parameters of the n levels obtained in step S9 into a two-dimensional line graph, find the corresponding level of the target cross-sectional area peak value in the graph, select the dielectric constant of the corresponding level coating layer, and define the stealth effect C (in dB) to evaluate the target's passive millimeter wave stealth effect. The definition is as follows:

[0068]

[0069] In equation (9), σ′ T′ σ′ represents the radiation cross-section of the target after passive millimeter-wave stealth. T The value of C represents the original radiation cross section of the target. The larger the value of C, the better the stealth effect of the stealth material.

[0070] Substituting equation (6) into equation (9), we obtain equation (10):

[0071]

[0072]

[0073]

[0074] σ″ in equation (11) T′ σ″ in equation (12) T The total brightness temperature of radiometer radiation cross section (TBTORRCS) is defined as the target, where ΔTafter iΔTbefore represents the brightness temperature difference between each pixel in the radiometer's radiation cross-section of the target after it has been coated with a stealth medium and the background. i The brightness temperature difference between each pixel in the radiometer's radiation cross-section of the target before it is coated with a stealth medium and the background.

[0075] S11. Substitute the n RRCS values ​​generated in step S9 into σ″ in equation (9). T′ Substitute the RRCS value generated in step S6 into σ″ in equation (9) T And plot the result C in equation (10) as a 2D line graph, see [reference]. Figure 9 and Figure 10 As shown, Figure 9 This is a 2D piecewise line plot of the C value under horizontal polarization. Figure 10 This is a 2D piecewise linear plot of the C value under vertical polarization. The level corresponding to the maximum C value is extracted from the piecewise linear plot, and the relative permittivity ε corresponding to that level is found in the contour plot generated in step S8. Select .

[0076] S12. The relative permittivity ε found in step S11 is... Select Substituting into the three-dimensional mesh model, using a relative permittivity of ε Select The material is coated on the top of a hexahedron of metallic dielectric, and then ray tracing is performed. After the ray tracing is completed, the brightness temperature is inverted from the end of each ray to the emission source point to obtain the brightness temperature at different locations in the detected scene, forming a brightness temperature map. (See reference...) Figure 11 and Figure 12 As shown, where Figure 11 This is a brightness temperature diagram under horizontal polarization. Figure 12 This is the brightness temperature diagram under vertical polarization.

[0077] S13. Perform ray tracing on the uncoated metallic hexahedron. After the ray tracing is completed, invert the brightness temperature from the end of each ray to the emission source point to obtain the brightness temperature at different locations in the detected scene, forming a brightness temperature map. (See reference...) Figure 13 and Figure 14 As shown, where Figure 13 This is a brightness temperature diagram under horizontal polarization. Figure 14 This is the brightness temperature diagram under vertical polarization.

[0078] S14. Using a relative permittivity of ε Conventional Traditional radar absorbing materials are applied to the top of a hexahedron of a metallic medium, followed by ray tracing. After the ray tracing is completed, the brightness temperature is inverted from the end of each ray back to the emission source point, obtaining the brightness temperature at different locations in the detected scene, forming a brightness temperature map. (See reference...) Figure 15 and Figure 16 As shown, where Figure 15 This is a brightness temperature diagram under horizontal polarization. Figure 16 This is the brightness temperature map under vertical polarization. Under horizontal polarization, a comparison is shown. Figure 11 The brightness temperature diagram of the stealth material identified by this technical solution is shown. Figure 13 The brightness temperature diagram before the stealth coating is shown. Figure 15 The brightness temperature diagram of the radar absorbing layer shown is as follows. Figure 11 The average brightness temperature difference between the top of the metal observation object and the environment is ΔT1 = 1.942 K. Figure 13 The average brightness temperature difference between the top of the metal observation object and the environment is ΔT2 = 129.562 K. Figure 15 The average brightness temperature difference between the top of the metal observation object and the environment is ΔT3 = 66.149 K, i.e., ΔT2 > ΔT3 > ΔT1. Under vertical polarization, the contrast... Figure 12 The brightness temperature diagram of the stealth material identified by this technical solution is shown. Figure 14 The brightness temperature diagram before the stealth coating is shown. Figure 16 The brightness temperature diagram of the radar absorbing layer shown is as follows. Figure 12 The average brightness temperature difference between the top of the metal observation object and the environment is ΔT4 = 1.674 K. Figure 14 The average brightness temperature difference between the top of the metal observation object and the environment is ΔT5 = 139.988 K. Figure 16 The average brightness temperature difference between the top of the metallic observation object and the environment is ΔT6 = 53.508 K, i.e., ΔT5 > ΔT6 > ΔT4. Therefore, the brightness temperature difference between the top of the metallic observation object coated with the stealth material found in this technical solution and the environment is significantly reduced compared with the brightness temperature difference between the top of the metallic observation object and the environment before coating, and the effect is better than coating with traditional radar absorbing layer materials.

[0079] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for selecting the best stealth coating material for a metal object in different environments, characterized in that, It comprises the following steps: S1, physically modeling the detected scene to obtain a three-dimensional virtual model of the detected scene; S2, subdivide the three-dimensional virtual model obtained in step S1 to obtain a three-dimensional subdivision model of the detected scene; S3, ray tracing the three-dimensional subdivision model obtained in step S2, and after the ray tracing part ends, inversely calculate the brightness temperature from the terminal of each ray to the emission source point to obtain the brightness temperature at different positions in the detected scene and form a brightness temperature map; S4, compare and find the brightness temperature difference between different surfaces of the target metal observation object and the environment background, and record the surface number that needs to be coated with a stealth coating; S5, coat the surface found and recorded in step S4 with a stealth coating; S6, repeat step S3 and record the average incident angle of the tracking ray of the coating surface; S7, assume the coating layer as an ideal smooth surface and draw an isogram; S8, extract the isogram drawn in step S7 and divide the reflectivity level of the coating layer into n levels; S9, use the n levels of coating layer reflectivity extracted in step S8 to replace the detected three-dimensional virtual model and perform n times of ray tracing and brightness temperature inversion, and then statistically analyze the target radiation cross-sectional area parameters of the coating surface after each brightness temperature inversion; S10, draw a two-dimensional broken line graph of the n levels of target radiation cross-sectional area parameters statistically analyzed in step S9, find the corresponding level of the target cross-sectional area peak in the graph, and select the dielectric constant of the corresponding level coating layer; S11, bring the dielectric constant obtained in step S10 into the three-dimensional virtual model of the detected scene and compare it with the brightness temperature imaging map of the metal observation object without coating medium; S12, change the millimeter wave radiometer observation angle and repeat steps S1 to S11 to observe and statistically analyze the influence of the millimeter wave radiometer observation angle on the selection of the stealth coating layer.

2. The method according to claim 1, wherein the optimal stealth coating material for the metal object in different environments is selected. In step S7, the average incident angle of the coating surface ray is brought into the reflectivity equation by Fresnel reflection law, the dielectric constant is set as the independent variable, the reflectivity is set as the dependent variable, and the isogram with the dependent variable as the reflectivity and the independent variable as the medium dielectric constant is drawn.

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