A method for quickly generating load distribution mesh data

Abstract

The application discloses a method for rapidly generating load distribution grid data, which comprises the following steps: firstly, importing an original catia three-dimensional model of an airplane as input into patran software; secondly, establishing a two-dimensional projection surface of a component in a geometry module or a grid module of the patran software, completing component load distribution grid division, and dividing the component grid type into a matrix type grid and a non-matrix type grid; thirdly, exporting component grid node coordinates in row order or column order to obtain grid node coordinate data; fourthly, arranging the grid node coordinate data into a matrix according to the position of the grid node coordinate data in the grid to generate a grid node coordinate data matrix; fifthly, calculating grid node face center point coordinates and area from the grid node data matrix; and finally, synchronously outputting a grid drawing CAD format file according to the grid node coordinate. The application has the advantages of small workload, low measurement error, high flexibility and wide application range.

Description

Technical Field

[0001] This invention relates to the field of aerodynamic load design technology for aircraft, and in particular to a method for rapidly generating load distribution grid data. Background Technology

[0002] In flight load calculations, the final result is the operating condition under which each component experiences maximum load, along with the magnitude and distribution of the load under each condition. The load distribution can be provided according to a pre-defined load distribution grid, and the reasonableness of the load distribution grid is a necessary condition for providing an accurate load distribution. Currently, the generated load distribution grid data is manually acquired and cannot be directly combined with the aerodynamic features of the original 3D digital model to create a 2D load distribution grid. This is especially true for V-tail components, where the 3D coordinates of the face center cannot be directly obtained, and the coordinates of the feature points of each component need to be manually measured. The actual grid division cannot be directly displayed, resulting in a large workload, limited applicability, and high measurement errors. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a method for rapidly generating load distribution grid data, thereby addressing the problems mentioned in the background art.

[0004] The technical problem solved by this invention is achieved by the following technical solution:

[0005] A method for rapidly generating load distribution grid data, comprising the following steps:

[0006] Step 1) Import the original CATIA 3D model of the aircraft into the Patran software as input;

[0007] Step 2) Create a two-dimensional projection surface of the component in the geometry or mesh module of the Patran software and complete the mesh generation for the component load distribution;

[0008] Step 3) Determine the component mesh type, classify the component mesh type into matrix mesh and non-matrix mesh, and then export the component mesh node coordinates in row order or column order to obtain the mesh node coordinate data;

[0009] Step 4) Arrange the grid node coordinate data into a matrix according to their positions in the grid to generate the grid node data matrix;

[0010] Step 5) Calculate the coordinates and area of ​​the grid face center point. The grid node data matrix generated in Step 4) is arranged in row and column order. The grid node data matrix is ​​calculated by using formula (1) and formula (2) for each divided unit grid node to obtain the coordinates and area of ​​the face center point of each unit grid. Finally, the grid face center point coordinates and area are obtained in order.

[0011] When dividing the grid, the shape of the unit grid includes both triangles and quadrilaterals. Therefore, when calculating the area and the coordinates of the face center, a quadrilateral is decomposed into two triangles. The Heron method is used to obtain the area of ​​the two triangles, and then they are summed to obtain the total area of ​​the quadrilateral. Formula (1) is as follows:

[0012]

[0013] Formula (2) for finding the coordinates of the center point of a surface is as follows:

[0014]

[0015] In formula (1) to formula (2):

[0016] i represents the i-th row in the grid node data matrix, and j represents the j-th column;

[0017] d1, d2, d3, d4, d5 represent the sides of the two triangles that make up the unit grid;

[0018] s1 represents the area of ​​triangle 1 with side lengths d1, d2, and d5;

[0019] s2 represents the area of ​​triangle 2 with side lengths d3, d4, and d5;

[0020] s represents the total area of ​​the quadrilateral;

[0021] x mid1 y mid1 Represents the coordinates of the center point of triangle 1;

[0022] x mid2 y mid2 Represents the coordinates of the center point of triangle 2;

[0023] x mid y mid Represents the coordinates of the center point of the quadrilateral;

[0024] Step 6) Based on the grid node coordinate data obtained in Step 4), synchronously output the grid map CAD format file for personalized labeling;

[0025] Step 7) Generate visual center points from the grid center point coordinates obtained in Step 5) to verify the center point data corresponding to the component;

[0026] Step 8) Derive the three-dimensional coordinates based on the coordinates of the grid center point using the global coordinate system as a reference.

[0027] In this invention, in step three), the rule for classifying the component mesh type is that if the number of nodes in all rows and all columns of the component mesh is the same, then it is a matrix mesh; otherwise, it is a non-matrix mesh.

[0028] In this invention, in step four), for non-matrix meshes, the mesh node coordinates required to generate the matrix are first supplemented. Specifically, the supplementation is as follows: initially input the number of points to be supplemented before each row (nb) and the number of points to be supplemented after each row (na), so that the coordinates of the nb points supplemented before each row are equal to the coordinates of the first point of the current row, and similarly, the coordinates of the na points supplemented after each row are equal to the coordinates of the last point of the current row. The supplemented point coordinates are inserted into the original non-matrix mesh mesh node coordinate file, and then the mesh node coordinate data are arranged into a matrix according to their positions in the mesh to generate the mesh node data matrix.

[0029] Beneficial effects:

[0030] 1) This invention can directly combine the aerodynamic features of the original three-dimensional digital model to divide a two-dimensional load distribution grid;

[0031] 2) This invention can accurately determine the coordinates of the center points of a grid arranged in a regular order and the grid area;

[0032] 3) This invention can obtain the three-dimensional coordinates of the face center point;

[0033] 4) This invention enables personalized identification of two-dimensional grid graphics;

[0034] 5) This invention has the advantages of low workload, low measurement error, high flexibility and wide range of applications. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a matrix-type grid in a preferred embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of a non-matrix mesh in a preferred embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram of the coordinates of the center point of the unit grid and the area calculation parameters in a preferred embodiment of the present invention.

[0038] Figure 4 This is a flowchart of a preferred embodiment of the present invention.

[0039] Figure 5 This is a visual schematic diagram of the longitudinal fuselage grid face center point verification in a preferred embodiment of the present invention.

[0040] Figure 6 This is a visual schematic diagram of the V-tail grid face center point verification in a preferred embodiment of the present invention. Detailed Implementation

[0041] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0042] See Figures 1-6 The method for rapidly generating load distribution grid data, using a V-tail and the aircraft fuselage as an example, is illustrated below. The specific steps are as follows:

[0043] Step 1) Import the CATIA 3D model of the aircraft fuselage and V-tail (hereinafter referred to as "V-tail") into the Patran software;

[0044] Step 2) In the geometry or mesh module of the Patran software, create a two-dimensional projection surface of the component and complete the load distribution mesh generation of the component, that is, create the fuselage group and V-tail group for easy viewing and management;

[0045] Step 3) Determine the component mesh type. The component mesh type is divided into matrix meshes and non-matrix meshes. The classification rule is: if all rows and all columns of the component mesh have the same number of nodes, it is a matrix mesh; otherwise, it is a non-matrix mesh. Matrix meshes and non-matrix meshes are as follows: Figure 1 ,Down Figure 2 As shown, the component mesh node coordinates are exported in row or column order to obtain the mesh node coordinate data;

[0046] For the aircraft fuselage, a two-dimensional projection surface of the longitudinal fuselage is established with the Y=0 plane as the projection surface. Since the shape of the projected longitudinal fuselage is irregular, it is a non-matrix mesh. Two-dimensional meshing is performed on it. Based on the load distribution experience, the meshing of the longitudinal fuselage does not need to be as dense as the wing surface mesh.

[0047] For the V-tail, since it is tilted in the global coordinate system, the V-tail chord plane is used as the projection plane. The V-tail is projected onto this plane, and a local two-dimensional coordinate system is established in this plane. Since the projection shape is regular, it is a matrix-type mesh. Two-dimensional meshes are divided into them. According to the load distribution experience, the chordal meshes of the airfoil, leading edge and control surface should be refined.

[0048] Step 4) Arrange the grid node coordinate data into a matrix according to their positions in the grid to generate the grid node data matrix. For non-matrix grids, first supplement the node coordinates required to generate the matrix. Specifically, supplement the coordinates as follows: initially input the number of points to be supplemented before each row (nb) and the number of points to be supplemented after each row (na), so that the coordinates of the nb points supplemented before each row are equal to the coordinates of the first point of the current row, and similarly, the coordinates of the na points supplemented after each row are equal to the coordinates of the last point of the current row. Insert the supplemented point coordinates into the original non-matrix grid node coordinate file, and then arrange the grid node coordinate data into a matrix according to their positions in the grid to generate the grid node data matrix.

[0049] Step 5) The grid node data matrix generated in Step 4) is used to calculate the coordinates and area of ​​the face center point of each unit grid node in the row and column order, and finally the coordinates and area of ​​the face center point of the longitudinal fuselage and V tail grid arranged in order are obtained.

[0050] When dividing the grid, the shape of the unit grid includes both triangles and quadrilaterals. Therefore, when calculating the area and the coordinates of the face center, a quadrilateral is decomposed into two triangles, such as... Figure 3 As shown;

[0051] The areas of triangle 1 and triangle 2 are obtained using Heron's method, and then summed to obtain the total area of ​​the quadrilateral. Formula (1) is as follows:

[0052]

[0053] Formula (2) for finding the coordinates of the center point of a surface is as follows:

[0054]

[0055]

[0056] In formula (1) to formula (2):

[0057] i represents the i-th row in the grid node data matrix, and j represents the j-th column;

[0058] d1, d2, d3, d4, d5 represent the sides of the two triangles that make up the unit grid;

[0059] s1 represents the area of ​​triangle 1 with side lengths d1, d2, and d5;

[0060] s2 represents the area of ​​triangle 2 with side lengths d3, d4, and d5;

[0061] s represents the total area of ​​the quadrilateral;

[0062] x mid1 y mid1 Represents the coordinates of the center point of triangle 1;

[0063] x mid2 y mid2 Represents the coordinates of the center point of triangle 2;

[0064] x mid y mid Represents the coordinates of the center point of the quadrilateral;

[0065] Step 6) Based on the grid node coordinate data obtained in Step 4), synchronously output the grid map CAD format file for personalized labeling;

[0066] Step 7) Generate visualized face center points from the grid center point coordinates of the longitudinal fuselage and V-tail obtained in Step 5), and verify the corresponding face center point data of the longitudinal fuselage and V-tail components, as shown in the attached figure. Figure 5 , Figure 6 As shown;

[0067] Step 8) Derive the three-dimensional coordinates based on the coordinates of the center point of the V-tail mesh using the global coordinate system as a reference.

[0068] In this embodiment, to obtain the coordinates of the center point of the three-dimensional mesh, the specific steps are as follows:

[0069] 1) If the projection plane is three-dimensional in the global coordinate system (such as a V-shaped tail fin), then first establish a two-dimensional local coordinate system on the projection plane, and output the coordinates of the mesh nodes in this two-dimensional coordinate system;

[0070] 2) Calculate the coordinates of the face center and the grid area in a two-dimensional coordinate system;

[0071] 3) Import the coordinates of the face center point in the two-dimensional coordinate system into Patran to obtain a graphical display of the face center point. Then select the global three-dimensional coordinate system to output the coordinates of the face center point. Thus, the three-dimensional coordinates of the face center point in the global three-dimensional coordinate system are obtained.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for rapidly generating load distribution grid data, characterized in that, The specific steps are as follows: Step 1) Import the original CATIA 3D model of the aircraft into the Patran software as input; Step 2) Create a 2D projection surface of the component in the geometry or mesh module of the Patran software and complete the mesh generation for the component load distribution; Step 3) Determine the component mesh type, classify the component mesh type into matrix mesh and non-matrix mesh, and then export the component mesh node coordinates in row order or column order to obtain the mesh node coordinate data; Step 4) Arrange the grid node coordinate data obtained in Step 3) into a matrix according to their positions in the grid to generate a grid node data matrix; The steps for generating a grid node data matrix from a non-matrix grid are as follows: First, supplement the grid node coordinates required for generating the matrix. Specifically, initially input the number of points to be supplemented before each row (nb) and the number of points to be supplemented after each row (na), so that the coordinates of the nb points supplemented before each row are equal to the coordinates of the first point of the current row. Similarly, the coordinates of the na points supplemented after each row are equal to the coordinates of the last point of the current row. Then, insert the supplemented point coordinates into the original non-matrix grid node coordinate file. Finally, arrange the grid node coordinate data into a matrix according to their positions in the grid to generate the grid node data matrix. Step 5) The grid node data matrix generated in Step 4) is calculated cyclically for each divided unit grid node in the order of rows and columns to obtain the coordinates of the face center point and the area of ​​each unit grid, and finally obtain the grid face center point coordinates and area arranged in order. Step 6) Based on the grid node coordinate data obtained in Step 4), synchronously output the grid map CAD format file for personalized identification; Step 7) Generate visual center point coordinates of the mesh face center points obtained in Step 5) for use in verifying the face center point data corresponding to the component; Step 8) Derive the 3D coordinates based on the coordinates of the grid center point using the global coordinate system as a reference.

2. The method for rapidly generating load distribution grid data according to claim 1, characterized in that, In step three), the rule for classifying component mesh types is that if the number of nodes in all rows and all columns of a component mesh is the same, it is a matrix mesh; otherwise, it is a non-matrix mesh.

3. The method for rapidly generating load distribution grid data according to claim 1, characterized in that, In step five, when dividing the grid, the shape of the unit grid node includes two shapes: triangle and quadrilateral. Therefore, when calculating the coordinates of the center point of the unit grid and the area, a quadrilateral is decomposed into two triangles.

4. The method for rapidly generating load distribution grid data according to claim 3, characterized in that, The area of ​​the face center of the unit mesh is obtained using Heron's method, which involves first calculating the areas of the two triangles and then summing them, as shown in formula (1) below: （1） Formula (2) for finding the coordinates of the center point of a surface is as follows: （2） In formula (1) ~ formula (2): i represents the i-th row in the grid node data matrix, and j represents the j-th column; d1, d2, d3, d4, d5 represent the sides of the two triangles that make up the unit grid; s1 represents the area of ​​triangle 1 with side lengths d1, d2, and d5; s2 represents the area of ​​triangle 2 with side lengths d3, d4, and d5; s represents the total area of ​​the quadrilateral; Represents the coordinates of the center point of triangle 1; Indicate the coordinates of the center point of triangle 2; Represents the coordinates of the center point of the quadrilateral.

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