A radar cover uniform variable thickness inner surface modeling method based on finite element grid thickness mapping
By combining finite element mesh thickness mapping and reverse engineering, the problems of low efficiency and poor accuracy in radar dome internal surface modeling in existing technologies have been solved. This method achieves efficient and accurate radar dome internal surface modeling, and the generated model meets the requirements of high-quality continuity and is suitable for complex curvature and different thickness distributions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN TIANYUAN MACHINERY CO LTD OF 081 ELECTRONICS GRP
- Filing Date
- 2026-02-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies struggle to efficiently and accurately convert variable-thickness design data into high-quality 3D internal surface models of radomes, leading to extended design cycles, increased costs, and model quality that relies on human experience.
A method based on finite element mesh thickness mapping is adopted. By offsetting the normal in three-dimensional space and combining reverse engineering reconstruction, a smooth and continuous inner surface is generated to ensure that the wall thickness at any point is consistent with the design thickness. Point cloud data is generated by finite element mesh generation and interpolation calculation, and then imported into reverse engineering software to reconstruct the inner surface.
It achieves high-precision and rapid modeling of the inner surface of the radome, and the generated model meets the G1 or even G2 continuity requirements, improving modeling efficiency and model quality, and is suitable for complex curvature and different thickness distributions.
Smart Images
Figure CN122113277A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aircraft structural design and computer-aided design technology, specifically relating to a method for constructing a three-dimensional digital model of a radome, and particularly a high-precision modeling method for the inner surface of a variable-thickness radome based on a combination of finite element mesh, thickness mapping and reverse engineering. Background Technology
[0002] A radome is a rectifying structure that protects a radar antenna from the influence of the external environment, and its electromagnetic transmission performance and structural strength are crucial. To optimize electromagnetic performance (such as transmittance and wavefront phase), modern high-performance radomes are often designed as variable-thickness structures, meaning that the thickness of the radome wall continuously varies at different locations in space according to the electromagnetic field distribution requirements.
[0003] In the design and manufacturing process of radomes, accurate three-dimensional geometric models are fundamental for simulation analysis, performance verification, and CNC machining. Currently, modeling of variable-thickness radomes, especially their internal surfaces, typically suffers from the following methods and limitations: 1. Parametric Modeling and Manual Adjustment Method: Designers create an external surface model based on the aerodynamic shape, and then manually calculate and offset it inward based on discrete thickness data to generate the internal surface. This method is inefficient, labor-intensive, and error-prone when dealing with complex thickness distributions. Furthermore, it is difficult to guarantee the smoothness and continuity of the generated surface (e.g., G1, G2 continuity), affecting subsequent analysis and manufacturing.
[0004] 2. Traditional constant thickness offset method: This method uses the "shelling" or "equidistant offset" function of CAD software. It is only applicable to radomes with constant wall thickness and cannot meet the design requirements of variable thickness, thus limiting its application scope.
[0005] 3. Variable thickness modeling method based on two-dimensional cross-sections: As proposed in Chinese Patent Publication No. CN104750892A, the inner surface is constructed by offsetting the outer cross-sectional line within a parallel cross-section. However, this method performs the offset in a two-dimensional plane, and the offset direction is not the true normal of the surface at that point. This leads to a deviation between the actual wall thickness and the designed thickness in three-dimensional space, especially when the surface curvature changes significantly, resulting in substantial errors.
[0006] In summary, existing technologies lack an efficient method to directly convert variable thickness design data into high-quality, manufacturable 3D internal surface models, resulting in extended design cycles, increased costs, and model quality that relies on human experience. Summary of the Invention
[0007] This invention aims to overcome the shortcomings of existing technologies and provide an efficient and high-precision method for modeling the uniformly variable thickness inner surface of a radome based on finite element mesh thickness mapping. This method ensures that the wall thickness at any point is strictly equal to the design thickness through three-dimensional spatial normal offset, and generates a smooth and continuous inner surface.
[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for modeling the uniformly variable thickness inner surface of a radome based on finite element mesh thickness mapping includes the following steps: S1. Obtain the surface model of the radar dome and, based on the electromagnetic performance design data, determine the set of thickness-coordinate discrete points on at least two vertical main sections. S2. Perform curve fitting on the thickness-coordinate discrete point set to obtain the thickness distribution function of each main section; S3. Perform finite element triangular mesh generation on the surface model, obtain the node coordinate information of each triangular element, and calculate the center point coordinates and element normal vector of each element. S4. For each triangular element, the design thickness value at that point is calculated by interpolation based on the spatial coordinates of its center point and the thickness distribution function. S5. Calculate the three-dimensional point cloud coordinate data corresponding to the variable thickness inner surface based on the center point coordinates of each triangular unit, the design thickness value, and the unit normal vector; S6. Import the three-dimensional point cloud coordinate data into computer-aided design software, and reconstruct and generate a continuous and smooth radome variable thickness inner surface using reverse engineering methods.
[0009] The principle is as follows: S1. Obtain the radome's external curved surface model and thickness design data: Extract the original radome's external curved surface CAD model; Based on the electromagnetic performance optimization results, obtain a series of discrete points on at least two main cross sections in different directions (such as the azimuth plane YOZ and the elevation plane XOZ), each point containing the axial coordinate Z and its corresponding design thickness value d.
[0010] S2. Fitting the thickness distribution function: Perform curve fitting on the discrete thickness data point set on each main section to obtain a continuous function (such as a polynomial function) of the thickness of each main section as a function of the axial coordinate Z.
[0011] S3. External Surface Meshing and Geometric Information Extraction: Import the external surface model into the finite element preprocessing software and discretize it into a triangular mesh model. Record the coordinates of the three nodes of each triangular element, and calculate the coordinates of the center point and its unit normal vector for each element.
[0012] S4. Spatial point design thickness interpolation calculation: Traverse all triangular elements, for the center point of each element, based on its spatial coordinates ( Using the thickness distribution function obtained in step S2, calculate the thickness value that the point should have if it were located at different main sections, and then calculate the thickness value based on the cylindrical coordinate azimuth of the point. The final design thickness value at the center point is calculated using an interpolation formula (such as linear interpolation or sine interpolation). .
[0013] S5. Generate internal surface point cloud data: For each triangular element, based on its center point coordinates, element normal vector, and calculated design thickness... The coordinates of corresponding points on the variable-thickness inner surface are accurately calculated by offsetting along the opposite direction of the normal. All calculated point coordinates are then output as a point cloud data file.
[0014] S6. Reverse reconstruction of inner surface: Import the generated point cloud data file into the reverse engineering module of 3D CAD software (such as CATIA), and after steps such as point cloud filtering, triangular mesh reconstruction, surface smoothing fitting and simplification, generate the final smooth and continuous variable thickness radar dome inner surface model.
[0015] The beneficial effects of this invention are as follows: 1. High accuracy: By calculating the normal of each grid cell and offsetting the thickness along the normal, the actual wall thickness at any point in three-dimensional space is highly consistent with the electromagnetic design thickness, avoiding the normal error caused by the two-dimensional section method.
[0016] 2. High speed: The entire process, from thickness data fitting, mesh processing, thickness mapping to point cloud generation, can be completed quickly using scripts or spreadsheet software, improving modeling efficiency and consistency.
[0017] 3. High model quality: Based on dense and accurate normal offset point clouds, and through mature inverse surface reconstruction technology, high-quality smooth inner surfaces that meet G1 or even G2 continuity requirements can be generated, providing a good geometric foundation for subsequent CAE analysis and CAM processing.
[0018] 4. High applicability: The method does not depend on a specific type of curved surface and is also applicable to radomes with complex curvatures. It can also be flexibly adapted to different thickness distribution functions and interpolation strategies. Attached Figure Description
[0019] Figure 1 This is a schematic diagram illustrating the coordinate system definition of the radome in an embodiment of the present invention.
[0020] Figure 2 This is a schematic diagram of the curved surface model of the radar dome to be processed in an embodiment of the present invention.
[0021] Figure 3 A schematic diagram of sampling for modeling the thickness of the radome surface.
[0022] Figure 4 This is a schematic diagram of the radome's curved surface after being divided into finite element triangular meshes.
[0023] Figure 5 A schematic diagram illustrating the import of variable thickness inner surface point cloud data generated by the method of this invention into CATIA software.
[0024] Figure 6 This is a schematic diagram of triangular mesh reconstruction based on imported point cloud data.
[0025] Figure 7 This is a schematic diagram illustrating the generation of the initial inner surface using the rapid surface reconstruction function.
[0026] Figure 8 This is a schematic diagram of the simplified and smoothed initial reconstructed surface.
[0027] Figure 9 This is a schematic diagram of the cross-section of the generated inner surface and the original outer surface along the circumferential direction, showing the wall thickness variation.
[0028] Figure 10 This is a schematic diagram of the cross-section of the generated inner surface and the original outer surface along the axial direction.
[0029] In the diagram: Radar outer surface 1, antenna aperture surface 2, antenna normal 3. Detailed Implementation
[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example
[0032] This embodiment uses a section of a curved surface of a certain type of radome as an example. For example... Figures 1 to 10 As shown in the figure, this embodiment provides a method for modeling the uniformly variable thickness inner surface of a radome based on finite element mesh thickness mapping. The specific steps are as follows: Step 1: Obtain design input.
[0033] 1. Export the radome outline surface from the model and save it as an IGES format file (e.g., ...). Figure 2 (As shown). The coordinate system is defined as follows: Figure 1 As shown: the origin O is located at the center of the antenna aperture 2, the Z-axis is perpendicular to the antenna aperture 2 and moves forward, the X-axis is perpendicular to the upward, and the Y-axis is determined by the right-hand rule. Figure 1 The outer surface 1 of the radome and the antenna normal 3 are shown.
[0035] 2. Obtain the thickness distribution data provided by the electromagnetic design. In this example, the design thickness values at five Z-coordinate positions are taken on the azimuth plane (YOZ plane, corresponding to section A) and the elevation plane (XOZ plane, corresponding to section B), as shown in Table 1.
[0036] Table 1 Discrete Data for Thickness Design Z-coordinate mm Azimuth thickness (mm) Pitch surface thickness (mm) 800 13 18 600 12.6 17.8 400 11.2 16 200 8.5 12.6 0 5 7.5 Step 2: Fit the thickness distribution curve.
[0037] Using the least squares method, the data from the azimuth and elevation planes in Table 1 were fitted into second-order polynomial functions about the Z coordinate.
[0038] The azimuth surface thickness function is obtained by solving: The thickness function of the pitch plane is obtained by solving: Step 3: Surface meshing and information extraction.
[0039] 1. Import the IGES file obtained in the first step into the preprocessing module of the finite element software. To ensure clear graphical display, select a portion of the radome surface (e.g., Figure 3 Perform the operation as shown in the figure.
[0040] 2. Surface meshing is performed on the curved surface, with the element type being triangular (e.g., ...). Figure 4 (As shown). Set an appropriate mesh size to ensure that surface features are captured while keeping the computational cost moderate.
[0041] 3. Export the mesh model information, including the numbers and coordinates of all triangular elements and their three nodes. ( ),( ),( ).
[0042] 4. For each triangular element, calculate the coordinates of its center point: ( )=( , , ) 5. Calculate the unit normal vector for each triangular element. The calculation formula is:
[0043] in These are the components of the triangular element normal unit vector in the X, Y, and Z directions.
[0044] Step 4: Calculate the point cloud coordinates of the inner surface.
[0045] Write a script or use spreadsheet software to iterate through all triangular cells and perform the following calculations for each cell: 1. Based on the Z-coordinate of the element center point Substitute the values obtained in the second step into the equations. and The function obtains the thickness value of that point under the assumptions of the two principal sections A and B. and .
[0046] 2. Calculate the center point. .
[0047] 3. Calculate the design thickness at the center point using the sine interpolation formula. :
[0048] This formula can guarantee accuracy in the azimuth plane ( Thickness is In the pitch plane ( Thickness is It transitions smoothly from other angles.
[0049] 4. Calculate the corresponding points of the internal surfaces. coordinate: ( )= .
[0050] Note that this offset is along the inner normal direction (negative direction).
[0051] 5. Calculate all ( , , The coordinates are written to a text file (such as an ASCII .asc file) to form the internal shape point cloud data. Figure 5 This illustrates the state of the point cloud after it has been imported into CATIA software.
[0052] Step 5: Reverse reconstruct the CAD surface.
[0053] In CATIA V5 software, perform the following operations: 1. Import point cloud: Enter the “Digitized Shape Editor” module and import the point cloud file generated in step 4.
[0054] 2. Point cloud preprocessing: Use the "Filter" or "Remove" tools to remove possible abnormal noise points as needed.
[0055] 3. Create triangular mesh surfaces: Use the "Mesh Creation" function to convert the point cloud into triangular mesh surfaces (e.g., Figure 6 (As shown).
[0056] 4. Automatic Surface Reconstruction: Switch to the "Quick Surface Reconstruction" module and use the "Automatic Surface" function to automatically generate segmented surface patches based on triangular meshes (e.g., Figure 7 (As shown).
[0057] 5. Surface Simplification and Smoothing: Enter the "Generative Shape Design" module and use the "Simplify" or "Healing" tools to merge, repair, and smooth the reconstructed surface to obtain a complete and smooth single surface (e.g., Figure 8 (As shown). This surface is the final high-precision variable-thickness radar dome internal surface model.
[0058] Step 6: Model Validation.
[0059] Sectioning by cross-section (e.g.) Figure 9 , Figure 10 Using a measuring tool (as shown), check the normal distance between the generated inner surface and the original outer surface to verify whether it matches the design thickness distribution in Table 1. The results show that the wall thickness of the inner surface generated by this method matches the design value well at all locations, and the surface is continuous and smooth. Example
[0061] The difference between this embodiment and Embodiment 1 is that a linear interpolation formula is used to calculate the design thickness in the fourth step. :
[0062] The range of values is mapped as ( This formula can also achieve thickness transition between two main sections, and is suitable for scenarios with different requirements for the transition law.
[0063] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that any equivalent substitutions or combinations of technical features made without departing from the principles and spirit of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for modeling the uniformly variable thickness inner surface of a radome based on finite element mesh thickness mapping, characterized in that, Includes the following steps: S1. Obtain the surface model of the radar dome and, based on the electromagnetic performance design data, determine the set of thickness-coordinate discrete points on at least two vertical main sections. S2. Perform curve fitting on the thickness-coordinate discrete point set to obtain the thickness distribution function of each main section; S3. Perform finite element triangular mesh generation on the surface model, obtain the node coordinate information of each triangular element, and calculate the center point coordinates and element normal vector of each element. S4. For each triangular element, the design thickness value at that point is calculated by interpolation based on the spatial coordinates of its center point and the thickness distribution function. S5. Calculate the three-dimensional point cloud coordinate data corresponding to the variable thickness inner surface based on the center point coordinates of each triangular unit, the design thickness value, and the unit normal vector; S6. Import the three-dimensional point cloud coordinate data into computer-aided design software, and reconstruct and generate a continuous and smooth radome variable thickness inner surface using reverse engineering methods.
2. The method according to claim 1, characterized in that, The at least two main cross sections in different directions include mutually orthogonal azimuth planes (YOZ plane) and pitch planes (XOZ plane).
3. The method according to claim 1 or 2, characterized in that, In step S2, the curve fitting uses the least squares method to fit the thickness-coordinate discrete point set into a polynomial function with respect to the axial coordinate Z.
4. The method according to claim 3, characterized in that, The polynomial function is an nth-order polynomial function, specifically a horizontal principal section polynomial function. and the polynomial function of the vertical principal section .
5. The method according to claim 1, characterized in that, In step S4, the interpolation calculation uses the following sine interpolation formula: ， in, The design thickness value is at the center point m, and A and B are the axial coordinates of the two main sections corresponding to this point. The thickness distribution function value of ) , It is the arctangent function in the four quadrants.
6. The method according to claim 1, characterized in that, In step S4, the interpolation calculation uses a linear interpolation formula: 。 7. The method according to claim 1, characterized in that, In step S3, the unit normal vector The calculation formula is: ， in, These are the components of the triangular element normal unit vector in the X, Y, and Z directions.
8. The method according to claim 1, characterized in that, In step S5, the corresponding points of the variable thickness inner surface coordinates The calculation formula is: 。