Finite element mesh generation method for honeycomb sandwich panels with cell wall defects

Abstract

The present invention belongs to the field of finite element mesh generation, and specifically relates to a finite element mesh generation method for a honeycomb sandwich panel containing cell wall missing defects. The finite element mesh generation method comprises the following steps: establishing a three-dimensional rectangular coordinate system of the honeycomb sandwich panel; creating a sheet geometric model of the honeycomb sandwich panel; creating a finite element mesh model of the honeycomb sandwich panel; numbering the honeycomb cell walls; randomly deleting the parallel cell walls; randomly deleting the oblique cell walls; and obtaining a finite element mesh model of the honeycomb sandwich panel containing cell wall missing defects. The finite element mesh generation method can automatically construct a finite element mesh model of the corresponding honeycomb sandwich panel containing cell wall missing defects, and is used to efficiently compare and analyze the effects of different cell wall missing ratios on the mechanical properties of the honeycomb sandwich panel, and evaluate the mechanical properties of the honeycomb sandwich panel containing cell wall missing defects.

Description

Technical Field

[0001] The invention belongs to the field of finite element mesh generation, and in particular relates to a finite element mesh generation method for a honeycomb sandwich panel containing cell wall missing defects. Background Art

[0002] Honeycomb sandwich panels are composed of a honeycomb core and a panel covering the honeycomb core. The panel and the honeycomb core are generally thin-walled structures. During the manufacturing, transportation or use process, cell wall missing defects may occur randomly on the honeycomb core at different rates.

[0003] Metal honeycomb sandwich structures have excellent mechanical properties and are widely used in the aerospace field. However, cell wall loss may occur randomly during the manufacturing process, and cell wall fracture may occur randomly during transportation or use. Both of these situations can be approximated or equivalent to cell wall loss. When constructing a finite element model of a honeycomb sandwich panel, shell elements are generally used to discretize the geometric model of the honeycomb sandwich panel. Accurately and efficiently evaluating the effects of different cell wall loss ratios on the mechanical properties of the structure is of great significance to the reusability and optimal design of honeycomb sandwich panels.

[0004] Currently, there is a need to develop a method that can efficiently construct a finite element model of honeycomb sandwich panels containing cell wall defects. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a finite element mesh generation method for a honeycomb sandwich panel containing cell wall missing defects.

[0006] The finite element mesh generation method of the honeycomb sandwich panel containing cell wall missing defects of the present invention comprises the following steps:

[0007] S100. Establishment of the three-dimensional rectangular coordinate system of the honeycomb sandwich panel

[0008] A three-dimensional rectangular coordinate system of the honeycomb sandwich panel is constructed by taking one vertex of the honeycomb sandwich panel as the origin, the honeycomb panel edge parallel to the cell wall as the X-axis, the other honeycomb panel edge perpendicular to the X-axis as the Y-axis, and the height direction of the honeycomb panel as the Z-axis;

[0009] S200. Create a geometric model of the honeycomb sandwich panel

[0010] According to the relevant parameters of the honeycomb sandwich panel, namely the honeycomb side length l0, honeycomb height h0, and the number of honeycombs in the X-axis direction n x , the number of cells in the Y-axis direction n y Create a geometric model of the honeycomb sandwich panel; where n x is an odd number;

[0011] S300. Create a finite element mesh model of a honeycomb sandwich panel

[0012] Set the number of mesh seeds n0, use quadrilateral units to discretize the geometric model of the honeycomb sandwich panel, and obtain the finite element mesh model of the honeycomb sandwich panel;

[0013] S400. Numbering of honeycomb cell walls

[0014] The honeycomb cell walls parallel to the X-axis are named parallel cell walls, and the remaining honeycomb cell walls are named oblique cell walls; according to the number of honeycombs n in each direction x and n y , get the number of parallel cell walls n p =n x n y +(n x +1) / 2, the number of oblique cell walls n s =2(n x +1)n y ; Number the parallel cell walls and oblique cell walls in sequence along the Y-axis direction;

[0015] S500. Random deletion of parallel cell walls

[0016] S510. Set the parallel cell wall ratio to be deleted p , multiplied by the number of parallel cell walls n p Then we can get the number of parallel cell walls to be deleted n pd , call the random number generation function, in [1, n p ] Randomly generate n in the interval pd different integers num pi , these integers are regarded as the parallel cell wall numbers in step S400;

[0017] S520. Calling a grid deletion function to sequentially delete grids of parallel cell walls represented by different numbers, including the following steps:

[0018] S521. For any integer num pi , calculate num pi / (2n y +1) and round it to get the column position of the parallel cell wall in the entire honeycomb pi , calculate num pi / (2n y +1) and take the remainder to get the row position of the parallel cell wall in the entire honeycomb. pi ;

[0019] S522. If row pi = 0, call the grid selection function to select (x min =(3column pi -1)l0,x max =3columnpi l0, z min =0,z max = h0) and call the grid deletion function to delete these grids;

[0020] S523. If 0 <row pi =n y +1, call the grid selection function to select (x min =(3column pi +0.5)l0,x max =(3column pi +1.5)l0, z min =0,z max = h0) and call the grid deletion function to delete these grids;

[0021] S524. If n y +1 <row pi , call the grid selection function to select (x min =(3column pi +2)l0,x max =(3column pi +3)l0, z min =0,z max = h0) and call the grid deletion function to delete these grids;

[0022] S600. Random deletion of oblique cell walls

[0023] S610. Set the ratio of the oblique cell wall to be deleted s , multiplied by the number of oblique cell walls n s Then we can get the number of oblique cell walls to be deleted n sd , call the random number generation function, in [1,n s ] Randomly generate n in the interval sd different integers, these integers are regarded as the oblique cell wall numbers in step S40;

[0024] S620. Calling a mesh deletion function to sequentially delete meshes of oblique cell walls represented by different numbers, including the following steps:

[0025] S621. For any integer num si , calculate num si / (2n y ) and round it off to get the column position of the oblique cell wall in the entire honeycomb si , calculate numsi / (2n y ) and take the remainder to get the row position of the oblique cell wall in the entire honeycomb. si ;

[0026] S622. If row si = 0, call the grid selection function to select (x min =(1.5column si -1.5)l0,x max =(1.5column si -1)l0,y min =0, z min =0,z max = h0) and call the grid deletion function to delete these grids;

[0027] S623. When row si ≠0, call the grid selection function to select (x min =1.5column si l0,x max =(1.5column si +0.5)l0, z min =0,z max = h0) and call the grid deletion function to delete these grids;

[0028] S700. Obtain the finite element mesh model of the honeycomb sandwich structure with cell wall missing defects.

[0029] The finite element mesh generation method of the honeycomb sandwich panel with cell wall missing defects of the present invention obtains the key parameters of the honeycomb sandwich panel, namely, the honeycomb side length l0, the honeycomb height h0, the number of honeycombs in the X-axis direction n, for a given honeycomb sandwich panel. x (an odd number), the number of cells in the Y-axis direction n y etc., set different parallel cell wall loss ratios p and the ratio of oblique cell wall loss s It can automatically construct the finite element mesh model of the corresponding honeycomb sandwich panel with cell wall missing defects, and can be used to efficiently compare and analyze the effects of different cell wall missing ratios on the mechanical properties of the honeycomb sandwich panel, and evaluate the mechanical properties of the honeycomb sandwich panel with cell wall missing defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the geometric model of the honeycomb sandwich panel;

[0031] Figure 2 It is the finite element mesh model of honeycomb sandwich panel;

[0032] Figure 3 It is a schematic diagram of the numbering of the honeycomb cell walls of the honeycomb sandwich panel;

[0033] Figure 4 The invention discloses a finite element mesh model of a honeycomb core containing cell wall missing defects obtained by the finite element mesh generation method of a honeycomb sandwich panel containing cell wall missing defects of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] The key parameters of a honeycomb sandwich structure with cell wall missing defects are: total length 407.02mm, total width 195mm, total height 8mm, honeycomb side length l0 8.66mm, honeycomb height h0 7mm, number of honeycombs in the X-axis direction n x is 31, the number of cells in the Y-axis direction is n y is 13, the number of grid seeds n0 is 6, and the parallel cell wall missing ratio ratio p The ratio of oblique cell wall loss is 26%. s is 10%.

[0037] S100. Establishment of the three-dimensional rectangular coordinate system of the honeycomb sandwich panel

[0038] Take one vertex of the honeycomb sandwich panel as the origin, the edge of the honeycomb panel parallel to the cell wall as the X-axis, the other edge of the honeycomb panel perpendicular to the X-axis as the Y-axis, and the height direction of the honeycomb panel as the Z-axis. Figure 1 The three-dimensional rectangular coordinate system of the honeycomb sandwich panel is shown.

[0039] S200. Create a geometric model of the honeycomb sandwich panel

[0040] According to the key parameters of the honeycomb sandwich panel, such as honeycomb side length l0 = 8.66 mm, honeycomb height h0 = 7 mm, number of honeycombs in the X-axis direction n x =31, number of cells in the Y-axis direction n y =13, create Figure 1 The geometric model of the honeycomb sandwich panel is shown.

[0041] S300. Create a finite element mesh model of a honeycomb sandwich panel

[0042] Set the number of grid seeds n0 = 6, and use quadrilateral elements to discretize the geometric model of the honeycomb sandwich panel, and obtain the following Figure 2 Finite element mesh model of honeycomb sandwich panel shown.

[0043] S400. Numbering of honeycomb cell walls

[0044] The honeycomb cell walls parallel to the X-axis are named parallel cell walls, and the remaining honeycomb cell walls are named oblique cell walls. x and n y , get the number of parallel cell walls n p =n x n y +(n x +1) / 2=419, the number of oblique cell walls n s =2(n x +1)n y =832. Figure 3 As shown, the parallel cell walls and oblique cell walls are numbered in sequence along the Y-axis direction.

[0045] S500. Random deletion of parallel cell walls

[0046] S510. Set the parallel cell wall ratio to be deleted p = 26%, multiplied by the number of parallel cell walls n p Then we can get the number of parallel cell walls to be deleted n pd =109, call the random number generation function, randomly generate 109 different integers in the interval [1,419], and regard these integers as the parallel cell wall numbers in step S400.

[0047] S520. Call the grid deletion function to delete the parallel cell wall grids represented by different numbers in turn:

[0048] If the generated integer is 27, the row position of the parallel cell wall in the entire honeycomb can be obtained. pi =1, row pi = 0, call the grid selection function to select (x min =17.32,x max =25.98,y min =7.5,y max =7.5,z min =0,z max =7) all grids within the range of mm, and call the grid deletion function to delete these grids;

[0049] If the generated integer is 40, the row position of the parallel cell wall in the entire honeycomb can be obtained. pi =1, row pi = 13, call the grid selection function to select (x min =30.31,x max =38.97,y min =15,y max =15,z min=0,z max =7) mm, and call the mesh deletion function to delete these meshes;

[0050] If the generated integer is 53, we can get the row position of the parallel cell wall in the entire honeycomb. pi =1, row pi = 26, call the grid selection function to select (x min =43.3,x max =51.96,y min =22.5,y max =22.5,z min =0,z max =7)mm, and call the mesh deletion function to delete these meshes.

[0051] S600. Random deletion of oblique cell walls

[0052] S610. Set the ratio of the oblique cell wall to be deleted s = 10%, multiplied by the number of oblique cell walls n s Then we can get the number of oblique cell walls to be deleted n sd =83, call the random number generation function, randomly generate 83 different integers in the interval [1,832], and regard these integers as the oblique cell wall numbers in step S40.

[0053] S620. Call the grid deletion function to delete the grids represented by different numbers in turn:

[0054] If the generated integer is 78, we can get the row position of the oblique cell wall in the entire honeycomb. si =3, row si = 0, call the grid selection function to select (x min =25.98,x max =34.64,y min =0,y max =7.5,z min =0,z max =7) all grids within the range of mm, and call the grid deletion function to delete these grids;

[0055] If the generated integer is 100, the row position of the oblique cell wall in the entire honeycomb can be obtained. si =3, row si = 22, call the grid selection function to select (x min =38.97,x max =43.3,y min =30,y max=37.5,z min =0,z max =7)mm, and call the mesh deletion function to delete these meshes.

[0056] S700. Get Figure 4 The finite element mesh model of a honeycomb sandwich structure with cell wall missing defects is shown.

[0057] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments, and they can be applied to various fields suitable for the present invention. For those familiar with the art, other improvements and modifications can be easily realized without departing from the principles of the present invention, and the present invention is not limited to the specific details and the legends shown and described here.

Claims

1. A finite element mesh generation method for a honeycomb sandwich panel containing cell wall defects, characterized in that: The following steps are involved: S100. Establishment of the three-dimensional rectangular coordinate system of the honeycomb sandwich panel A three-dimensional rectangular coordinate system of the honeycomb sandwich panel is constructed by taking one vertex of the honeycomb sandwich panel as the origin, the honeycomb panel edge parallel to the cell wall as the X-axis, the other honeycomb panel edge perpendicular to the X-axis as the Y-axis, and the height direction of the honeycomb panel as the Z-axis; S200. Create a geometric model of the honeycomb sandwich panel According to the relevant parameters of the honeycomb sandwich panel, namely the honeycomb side length l0, honeycomb height h0, and the number of honeycombs in the X-axis direction n x , the number of cells in the Y-axis direction n y Create a geometric model of the honeycomb sandwich panel; where n x is an odd number; S300. Create a finite element mesh model of a honeycomb sandwich panel Set the number of mesh seeds n0, use quadrilateral units to discretize the geometric model of the honeycomb sandwich panel, and obtain the finite element mesh model of the honeycomb sandwich panel; S400. Numbering of honeycomb cell walls The honeycomb cell walls parallel to the X-axis are named parallel cell walls, and the remaining honeycomb cell walls are named oblique cell walls; according to the number of honeycombs n in each direction x and n y , get the number of parallel cell walls n p =n x n y +(n x +1) / 2, the number of oblique cell walls n s =2(n x +1)n y ; Number the parallel cell walls and oblique cell walls in sequence along the Y-axis direction; S500. Random deletion of parallel cell walls S510. Set the parallel cell wall ratio to be deleted p , multiplied by the number of parallel cell walls n p Then we can get the number of parallel cell walls to be deleted n pd , call the random number generation function, in [1, n p ] Randomly generate n in the interval pd different integers num pi , these integers are regarded as the parallel cell wall numbers in step S400; S520. Calling a grid deletion function to sequentially delete grids of parallel cell walls represented by different numbers, including the following steps: S521. For any integer num pi , calculate num pi / (2n y +1) and round it to get the column position of the parallel cell wall in the entire honeycomb pi , calculate num pi / (2n y +1) and take the remainder to get the row position of the parallel cell wall in the entire honeycomb. pi ; S522. If row pi = 0, call the grid selection function to select (x min =(3column pi -1)l0,x max =3column pi l0, z min =0,z max = h0) and call the grid deletion function to delete these grids; S523. If 0<row pi =n y +1, call the grid selection function to select (x min =(3column pi +0.5)l0,x max =(3column pi +1.5)l0, z min =0,z max = h0) and call the grid deletion function to delete these grids; 524. If n y +1<row pi , call the grid selection function to select (x min =(3column pi +2)l0,x max =(3column pi +3)l0, z min =0,z max = h0) and call the grid deletion function to delete these grids; S600. Random deletion of oblique cell walls S610. Set the ratio of the oblique cell wall to be deleted s , multiplied by the number of oblique cell walls n s Then we can get the number of oblique cell walls to be deleted n sd , call the random number generation function, in [1,n s ] Randomly generate n in the interval sd different integers, which are regarded as the oblique cell wall numbers in step S40; S620. Calling a mesh deletion function to sequentially delete meshes of oblique cell walls represented by different numbers, including the following steps: S621. For any integer num si , calculate num si / (2n y ) and round it off to get the column position of the oblique cell wall in the entire honeycomb si , calculate num si / (2n y ) and take the remainder to get the row position of the oblique cell wall in the entire honeycomb. si ; S622. If row si = 0, call the grid selection function to select (x min =(1.5column si -1.5)l0,x max =(1.5column si -1)l0,y min =0, z min =0,z max = h0) and call the grid deletion function to delete these grids; S623. When row si ≠0, call the grid selection function to select (x min =1.5column si l0,x max =(1.5column si +0.5)l0, z min =0,z max = h0) and call the grid deletion function to delete these grids; S700. Obtain the finite element mesh model of the honeycomb sandwich structure with cell wall missing defects.

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