Finite element automatic loading method for multi-condition aerodynamic loads of airborne radar antenna cover

Abstract

The present invention relates to a multi-condition aerodynamic load finite element automatic loading method for a swivel cover of an airborne radar antenna. The method comprises obtaining the aerodynamic load of array points on the swivel cover surface under different attitude conditions, forming a load data file, and forming a position file in the form of local coordinates for the positions of the array points; performing finite element mesh division on a swivel cover structure model, exporting the unit and node information files of the mesh and a finite element model containing unit composite material ply attributes; converting the finite element mesh node coordinates into local coordinates, and performing coordinate conversion on the node local coordinates according to the rotation angle; fitting the aerodynamic load interpolation to the finite element mesh nodes, and obtaining the air pressure parameter values ​​of each unit by the node average method, and generating a load field file; importing the Hypermesh mesh model and the load field file into Patran software, and carrying out the rigidity analysis and verification of the swivel cover. The method has good versatility and saves a lot of time for similar swivel cover aerodynamic load analysis and design.

Description

Technical Field

[0001] The invention relates to the field of antenna swivel cover design simulation, and in particular to a multi-operating-condition aerodynamic load finite element automatic loading method for an airborne radar antenna swivel cover. Background Art

[0002] The antenna hood is a composite material structure installed outside the antenna array of the airborne early warning radar, which plays the role of wave transmission and antenna protection. On the premise of meeting the requirements of telecommunications energy, the hood must also withstand the severe aerodynamic loads under different working conditions such as various angles of attack and flight speeds, which plays a very important role in the safety of aircraft and radar. For a radome that can rotate 360°, it is also necessary to consider the rigidity and strength performance of the structure at different rotation angles, which places high demands on the design of the hood.

[0003] Aerodynamic loads are the main loads borne by the antenna hood. In the hood design process, the aerodynamic load pressure parameter information of the hood surface distribution points under different working conditions is generally obtained through wind tunnel tests or fluid analysis software, and then the pressure value of the solid finite element grid node is obtained through the interpolation fitting algorithm, and finally the pressure value of each grid unit is obtained. Finally, the unit load under different working conditions is applied to each grid unit in the finite element software as the load boundary condition of the finite element model, and simulation analysis and calculation are carried out to evaluate the rigidity and strength of the hood structure. Due to the large number of aerodynamic load conditions and the data exchange between different software, the manual loading method is very labor-intensive, which brings great difficulties to the detailed design verification of the hood. Therefore, it is necessary to design an efficient hood analysis method to solve the problems existing in the existing means. Summary of the invention

[0004] In order to solve the existing technical problems, the present invention provides a finite element automatic loading method for multi-condition aerodynamic loads of an airborne radar antenna rotary cover.

[0005] The specific content of the present invention is as follows: A multi-condition aerodynamic load finite element automatic loading method for an airborne radar antenna rotary cover comprises the following steps:

[0006] Step 1: Obtain the aerodynamic loads of the array points on the surface of the rotary cover under different attitude conditions and form a load data file. The positions of the array points form a position file in the form of local coordinates;

[0007] Step 2: Perform finite element meshing on the hood structure model, and export the mesh unit and node information files and the finite element model containing unit composite material ply attributes, wherein the unit information includes the attributes, number and node number of each unit, and the node information includes the node number and the node X, Y, and Z coordinates;

[0008] Step 3: Convert the finite element mesh node coordinates in step 2 into local coordinates, and perform coordinate conversion on the local coordinates of the nodes according to the rotation angle; on this basis, interpolate and fit the aerodynamic loads of the array points at a certain working angle in step 1 to the finite element mesh nodes, and obtain the air pressure parameter values ​​of each unit by the node averaging method, and finally generate a load field file that can be read by Patran;

[0009] Step 4: Import the Hypermesh mesh model of step 2 and the load field file of step 3 into Patran software to conduct stiffness analysis and verification of the swivel cover.

[0010] Furthermore, step 1 includes: obtaining the aerodynamic loads of the array points on the surface of the swirl hood under different attitude conditions by means of wind dynamic tests or fluid simulation analysis, extracting the aerodynamic loads at the array point positions in the local coordinate system of the swirl hood, and exporting them in the form of a file to generate an aerodynamic load condition information file, wherein the load information respectively includes the loads on the upper and lower surfaces of the swirl hood, and is displayed in different lines of the file.

[0011] Further, step 2 includes: using finite element software to perform shell meshing on the geometric model, and exporting unit information files and node information files; wherein the unit can be in the form of a triangle or a quadrilateral;

[0012] Furthermore, step 3 includes:

[0013] Step 31: Read the finite element mesh node information file in step 2, and generate node information in the local coordinate system through coordinate transformation according to the rotation angle requirement;

[0014] Step 32: In the same local coordinate system, the array point aerodynamic load is interpolated to the finite element node by the quadratic interpolation method to generate a node aerodynamic load information file. When interpolating, the node position information must be identified first, and the array point aerodynamic load matrix interpolation of the upper surface or lower surface is determined by the position;

[0015] Step 33: Import the finite element unit information file of step 2, and obtain the unit aerodynamic load information file through the node averaging method. This file can be directly read by the finite element analysis software Patran through the load field file.

[0016] Furthermore, step 4 includes: importing the finite element model file of step 2 and the load field file of step 3 into Patran software, carrying out stiffness analysis of the swivel hood under different aerodynamic load conditions, and providing verification and optimization for the design of the structure.

[0017] The present invention provides a method for automatically loading aerodynamic loads of a rotary hood under multiple working conditions to overcome the defects of manual loading. The method develops a method for processing aerodynamic loads of a rotary hood based on Matlab, which can read aerodynamic load files under different working conditions at one time, automatically convert them into finite element loads under different rotation angles, and sequentially generate load field files that can be directly read by Patran software, which is convenient for finite element simulation analysis and verification of the rotary hood structure under multiple working conditions and different rotation angles. The method can take into account different hood shapes, different rotation angles, and angles of attack, has good versatility, and saves a lot of time for similar rotary hood analysis and design. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific implementation of the present invention will be further explained below in conjunction with the accompanying drawings.

[0019] Figure 1 It is a flow chart of the pneumatic load finite element automatic loading method of the present invention;

[0020] Figure 2 This is a schematic diagram of the local coordinates of the aerodynamic load of the swivel cover;

[0021] Figure 3 Schematic diagram for reading load data files;

[0022] Figure 4 is a schematic diagram of a unit information file;

[0023] Figure 5 This is a schematic diagram of a node information file;

[0024] Figure 6 is a schematic diagram of the finite element mesh model;

[0025] Figure 7 is a schematic diagram of the coordinate conversion program;

[0026] Figure 8 It is a schematic diagram of aerodynamic load interpolation of finite element nodes;

[0027] Fig. 9 It is a schematic diagram of the unit load field file;

[0028] Fig.10 This is the displacement cloud diagram of the hood structure under the action of aerodynamic load;

[0029] Fig.11 Failure cloud diagram of the hood structure under aerodynamic load. DETAILED DESCRIPTION

[0030] The technical process and implementation method in the embodiment of the present invention are described in detail below in conjunction with the accompanying drawings. The described embodiments are part of the embodiments of the present invention, rather than all the embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but cannot be understood as limiting the present invention.

[0031] Figure 1 The figure is a flow chart of the automatic finite element loading of the multi-condition aerodynamic load of the rotary cover according to an embodiment of the present invention. In this example, the technical method is implemented based on MATLAB, the meshing is performed using Hypermesh software, and the simulation calculation is performed using Patran / Nastran software. Figure 1 The finite element automatic loading process of the multi-condition aerodynamic load of the rotary cover shown includes the following steps:

[0032] Step 1: Use wind test or fluid simulation analysis to obtain the aerodynamic load (air pressure parameter) of the array points on the hood surface under different attitude conditions, and generate a load data file Loadcase_i.txt. The positions of the array points are formed into a position file in the form of local coordinates. On this basis, through coordinate conversion, generate aerodynamic load files under different rotation angles for each working condition.

[0033] The local coordinates of a swirl cover model are as follows Figure 2 As shown in the figure, when the array is arranged, m points are arranged in the Z direction with the disk radius as the reference length, and 2n points are arranged in the X direction with the chord length as the reference length (n points are arranged on the upper and lower surfaces of the hood) to form an aerodynamic load data file. The data file has 2n rows and m columns of data. Figure 3 The program (including reading in the test load data file, opening the blowing test data record and dividing the swivel cover into two layers, upper and lower) reads in the test load data file and can read multiple files at one time.

[0034] Step 2: Perform finite element meshing on the hood structure model, and export the mesh unit, node information file, and finite element model containing unit composite material ply attributes (such as Figure 4-Figure 6 The unit information includes the properties of each unit (triangular unit or quadrilateral unit), the number and the node number; the node information includes the node number and the node X, Y, Z coordinates.

[0035] Step 3: Convert the finite element mesh node coordinates of step 2 into local coordinates, and perform coordinate transformation on the node local coordinates according to the rotation angle (such as Figure 7 As shown, including the classical coordinate transformation, the local coordinate system rotates counterclockwise along the Y axis; counterclockwise is positive, theta angle), on this basis, the quadratic spline interpolation of the aerodynamic load of the array points under a certain working angle in step 1 is fitted to the finite element mesh nodes (such as Figure 8As shown), the interpolation function is as follows:

[0036] [P(i)]=interp2(X,Z,PrePos,Xp,Zp,'spline')

[0037] Generate the node aerodynamic load information file Loadcase_i-k.txt, the format of which is shown in Table 1:

[0038] Table 1 Node aerodynamic load information file

[0039] Node Number Aerodynamic load value i <![CDATA[P i ]]> j <![CDATA[P j ]]> k <![CDATA[P k ]]>

[0040] The air pressure parameter value of each unit is obtained by the node average method, and finally a load field file Pe_i-k.csv readable by Patran is generated, as shown in Fig. 9 As shown, set the unit number and starting load value to even.

[0041] Step 4: Import the Hypermesh mesh model of step 2 and the load field file of step 3 into Patran software to conduct a stiffness analysis and verification of the swivel cover. The displacement cloud map and failure cloud map of the swivel cover structure under a certain aerodynamic load condition are shown in the figure below: Fig.10 and Fig.11 shown.

[0042] Many specific details are described in the above description to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited to the specific implementation disclosed above. At the same time, any person familiar with the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A multi-condition aerodynamic load finite element automatic loading method for an airborne radar antenna hood, characterized by: The steps include: Step 1: Obtain the aerodynamic loads of the array points on the surface of the rotary cover under different attitude conditions and form a load data file. The positions of the array points form a position file in the form of local coordinates; Step 2: Perform finite element meshing on the hood structure model, and export the mesh unit and node information files and the finite element model containing unit composite material ply attributes, wherein the unit information includes the attributes, number and node number of each unit, and the node information includes the node number and the node X, Y, and Z coordinates; Step 3: Convert the finite element mesh node coordinates in step 2 into local coordinates, and perform coordinate conversion on the local coordinates of the nodes according to the rotation angle; on this basis, interpolate and fit the aerodynamic loads of the array points at a certain working angle in step 1 to the finite element mesh nodes, and obtain the air pressure parameter values ​​of each unit by the node averaging method, and finally generate a load field file that can be read by Patran; Step 4: Import the Hypermesh mesh model of step 2 and the load field file of step 3 into Patran software to conduct stiffness analysis and verification of the swivel cover.

2. The multi-condition aerodynamic load finite element automatic loading method of the airborne radar antenna rotary cover according to claim 1 is characterized by: Step 1 includes: obtaining the aerodynamic loads of the array points on the surface of the swirl hood under different attitude conditions by means of wind dynamic tests or fluid simulation analysis, extracting the aerodynamic loads at the array point positions in the local coordinate system of the swirl hood, and exporting them in the form of a file to generate an aerodynamic load condition information file. The load information includes the loads on the upper and lower surfaces of the swirl hood respectively, and is displayed in different lines of the file.

3. The multi-condition aerodynamic load finite element automatic loading method of the airborne radar antenna rotary cover according to claim 1 is characterized by: Step 2 includes: using finite element software to perform shell meshing on the geometric model, and exporting unit information files and node information files; wherein the unit can be in two forms: a triangle or a quadrilateral.

4. The multi-condition aerodynamic load finite element automatic loading method of the airborne radar antenna rotary cover according to claim 1 is characterized by: Step 3 includes: Step 31: Read the finite element mesh node information file in step 2, and generate node information in the local coordinate system through coordinate transformation according to the rotation angle requirement; Step 32: In the same local coordinate system, the array point aerodynamic load is interpolated to the finite element node by the quadratic interpolation method to generate a node aerodynamic load information file. When interpolating, the node position information must be identified first, and the array point aerodynamic load matrix interpolation of the upper surface or lower surface is determined by the position; Step 33: Import the finite element unit information file of step 2, and obtain the unit aerodynamic load information file through the node averaging method. This file can be directly read by the finite element analysis software Patran through the load field file.

5. The multi-condition aerodynamic load finite element automatic loading method of the airborne radar antenna rotary cover according to claim 1 is characterized by: Step 4 includes: importing the finite element model file of step 2 and the load field file of step 3 into Patran software, conducting stiffness and strength analysis of the swivel hood under different aerodynamic load conditions, and providing verification and optimization for the design of the structure.

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