CN109948206B - A Parametric Modeling Method of Plate Finite Element Mesh for Diamond Pattern Processing by High Energy Beam - Google Patents

Abstract

The invention provides a method for parametric modeling of flat plate finite element grids for processing rhombus patterns by high-energy beams. A rhombic hexahedral grid is constructed by using nodes to complete the division of flat-plate grids including groove lines of high-energy beams; Four end faces; then according to the proportional relationship between the high-energy beam slot line and the width and height of the plate, the number of cells in the defect area of the high-energy beam slot line is determined; secondly, the area network of the defect area of the high-energy beam slot line is deleted along the width and height of the plate respectively. The grid completes the modeling; finally, the node and element information of the grid is output according to the format requirements of the finite element software. The invention can realize the high-energy beam processing diamond pattern flat plate finite element grid modeling with different geometric features, the method is simple and efficient, and the projectile body is used for strength analysis.

Description

A Parametric Modeling Method of Plate Finite Element Mesh for Diamond Pattern Processing by High Energy Beam

technical field

The invention relates to the technical field of ammunition, in particular to a method for parametric modeling of flat plate finite element grids for processing diamond patterns with high-energy beams.

Background technique

In order to improve the power of the warhead, the use of high-energy beam pre-control technology can enable the projectile to obtain pre-control fragments with relatively consistent shape and quality under detonation loading, thereby improving the power of the warhead. The high-energy beam pre-control technology uses high-energy beams such as electron beams, laser beams or ion beams to rapidly heat the material locally to a molten state, and the projectile body rapidly cools the molten metal, forming a regional unit on the projectile body to control the fragmentation of the projectile body. The high-energy beam rhombic groove means that the unit shape of the high-energy beam grooving is a rhombus. When designing the diamond-shaped groove for high-energy beams of the projectile, it is necessary to analyze the projectile strength of the diamond-shaped groove. Generally, a flat plate specimen can be taken on the projectile for analysis. Through the tensile test of the high-energy beam grooved plate, the influence of different groove parameters on the projectile strength can be studied. Combined with the numerical simulation analysis, the influence law of the high-energy beam groove on the projectile strength can be obtained. However, due to the complex geometry of the flat plate high-energy beam diamond groove, the region processed by the high-energy beam has a complex composition, including melting, transition, and defect regions, as shown in Figure 1.

However, due to the complex geometry of flat rhombus grooves, the establishment of finite element meshes for flat rhombus grooves using commercial modeling software is very time-consuming. First, build a 3D model of the diamond-shaped grooved plate, and then import the finite element software for mesh division. Generally, tetrahedral mesh is used, and the accuracy is not high; if hexahedral mesh is used, one of the grooves needs to be divided first, and then mirrored. Copy to other grooves, but if the angle of each groove is different, it cannot be mirrored directly, and it needs to be divided again, and the steps are cumbersome. In addition, if the feature size of the groove needs to be changed, the finite element mesh needs to be re-divided. A large number of repeated operations in modeling are cumbersome and error-prone, which seriously affects the design efficiency.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a method for parametric modeling of flat plate finite element meshes with diamond-shaped patterns processed by high-energy beams, which can realize the modeling of flat-plate finite element meshes with diamond-shaped patterns processed by high-energy beams with different geometric features, and the method is simple and convenient. High efficiency, for projectile strength analysis.

The technical scheme adopted by the present invention is as follows:

A method for parametric modeling of flat plate finite element mesh for processing diamond pattern by high-energy beam, comprising the following steps:

Step 1. Use nodes to construct a rhombic hexahedral mesh, and complete the plate mesh division including the high-energy beam groove lines;

Step 2. Fill up the four end faces around the flat grid;

Step 3: Determine the number of cells in the defect area of the high-energy beam slot line according to the proportional relationship between the high-energy beam slot line and the width and height of the plate;

Step 4. Complete the modeling by deleting the regional grid of the defect area of the high-energy beam groove line along the width and height of the plate respectively;

Step 4: Output the node and element information of the mesh according to the format requirements of the finite element software.

Further, taking the length direction of the flat plate as the X direction, the specific method of the step 1 is:

Step 101: Calculate the division fractions in the X, Y and Z directions under the Cartesian coordinate system, and set the division fractions in the Z direction;

Step 102, generating nodes according to the division fractions in the X, Y and Z directions;

Step 103, moving the node along the positive X direction, so that the connection line between the moving node and the original node in the Y direction and the X direction are half of the groove angle;

Step 104: Determine the grid area of the high-energy beam groove line in the Z direction of the groove according to the groove depth, the thickness of the plate and the Z-direction section fraction;

Step 105: Move the node in the Z direction to make the groove bottom node and the depth of the groove consistent; at the same time, move the node in the Z direction to make the height of the upper node in the defect area of the groove line consistent with the height of the defect area;

Step 106 , using nodes to construct a rhombus element to obtain a rhombic hexahedron mesh including high-energy beam groove lines.

Further, the concrete method of described step 2 is:

Step 201. Two end faces in the X direction: copy the nodes of the first column and the end column of the X direction, and move them in the positive and negative directions of the X direction to obtain the end face nodes of the two end faces; The node copied and moved is collinear with the node copied and moved from the first column or the end column;

Two end faces in the Y direction: Copy the nodes in the two columns at the start and the end in the Y direction, and move them along the positive and negative directions of the Y direction to obtain the end nodes of the two end faces;

Step 202 , constructing end face units of four end faces from nodes.

Further, the moving method of step 201 is:

In the X direction: L _c /2N _x is the moving distance of one column at the beginning and one column at the end, and L _c /N _x is the moving distance of the nodes that have moved in the X direction after copying, L _c is the length of the plate, and N _x is the cross section in the X direction Fraction;

In the Y direction: the movement distance of the first column at the start end and the last column at the end end can be b/N _y , the movement distance of the second column at the start end and the second column at the end end is 2b/N _y , b is the width of the plate, and N _y is Y Orientation section fraction.

Further, in the step 202, the specific method of constructing the end face unit by the nodes is as follows: 8 nodes construct a unit, according to the first z, then y, and then the x direction stores the nodes, and the node index index _nodei is calculated as follows, i, j, k is the node index in the three directions of X, Y, and Z, respectively, N _x is the division fraction in the X direction, N _y is the division fraction in the Y direction, and N _z is the division fraction in the Z direction.

Further, the concrete method of described step 3 is:

Step 301: Determine the transition zone area unit by the number of grooved spacing units in the Y direction and the number of grooved units in the Z direction;

Step 302: Determine the melting zone area unit by the number of groove interval units in the Y direction and the number of groove units in the Z direction;

Step 303 , determining the defect area region unit according to the number of groove spacing units in the Y direction and the number of groove units in the Z direction.

Beneficial effects:

1. The present invention can realize the high-energy beam processing rhombus-shaped flat plate finite element mesh modeling with different geometric features. Since the processing pattern is rhombus, this method directly constructs a rhombic hexahedral mesh for division, which is simple and easy to implement; if the high-energy beam needs to be changed The feature size of the slot line can be modeled only by changing the geometric feature parameters of the rhombic hexahedral mesh, which avoids the operation of re-establishing the 3D model and dividing the finite element mesh while changing the feature size of the high-energy beam slot line, avoiding the need for analysis. The personnel brought a lot of repetitive work, which solved the problems of complex geometry of the high-energy beam processing diamond pattern plate and the cumbersome process of establishing the finite element mesh, which provided convenience and high efficiency for the projectile analysis of the high-energy beam processing diamond pattern.

2. The present invention constructs a rhombic hexahedron mesh by moving nodes, precisely controls the size of the high-energy beam slot lines by changing the geometric features of the nodes, and has a fast response speed.

3. The present invention moves and complements four end faces by duplicating the end nodes to construct a rectangular end face. The end faces have good consistency and are convenient for docking with other models.

4. The present invention limits the moving distance of the end nodes, so that the constructed rectangular end face mesh is neither too large nor too small, so the calculation time of the finite element step size will not be affected by the size of the mesh.

Description of drawings

Fig. 1 is a schematic diagram of model area distribution based on high-energy beam processing;

Fig. 2 is the front view of the flat rhombic hexahedron grid of the present invention;

3 is a partial cross-sectional view of a flat panel of the present invention;

Fig. 4 is the schematic diagram of rhombus side length of the present invention;

Fig. 5 is the schematic diagram before the node of the present invention moves along the X direction;

Fig. 6 is the schematic diagram after the node of the present invention moves along the X direction;

7 is a schematic diagram of the index sequence of 8 nodes of the present invention constructing a unit;

8 is a schematic diagram of node movement of four end faces of the present invention;

Fig. 9 is the mesh division schematic diagram of the end face unit of the present invention;

FIG. 10 is a schematic diagram of mesh division of a flat plate high-energy beam rhombic hexahedron according to the present invention;

11 is a schematic diagram of the rhombic hexahedral mesh division of the high-energy beam slot line of the present invention;

Fig. 12 is a left side view of the present invention after the flat plate mesh is divided.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The invention provides a method for parametric modeling of flat plate finite element grids for processing diamond patterns by high-energy beams. The rhombic hexahedral grid is constructed by using nodes to divide the plate grids including the groove lines of the high-energy beams. Then, according to the proportional relationship between the high-energy beam slot line and the width and height of the plate, the number of cells in the defect area of the high-energy beam slot line is determined, and the area grid of the defect area of the high-energy beam slot line is deleted along the width and height of the plate respectively to complete the construction. The mold, as shown in Figure 10, Figure 11 and Figure 12, specifically includes the following steps:

Step 1. Summarize the geometric features of the diamond-shaped grooves of the flat plate high-energy beam;

Plate thickness t = 10mm, plate width b = 20mm, plate length L _c = 100mm, groove width w = 1mm, groove depth h = 5mm, groove interval a = 10mm, groove angle θ = 90°, groove line The number of cells in the intersecting rhombus along the width direction of the groove is N=3, the height of the defect area is h ₀ =1 mm, and the ratio of the width of the melted area to the width of the groove is S ₀ =1/3. As shown in Figure 2, Figure 3 and Figure 4.

Step 2. Calculate the side length of the rhombus obtained by the intersection of the groove lines;

As shown in Figure 4, the side length of the rhombus obtained from the intersection of the groove lines is represented by l, that is, the side length of the rhombic hexahedron mesh.

Step 3. Calculate the section fractions in the X, Y, and Z directions under the Cartesian coordinate system;

The length direction of the plate is taken as the X direction, the X-direction section is N _x , the Y-direction section is N _y , and the Z-direction section is N _z . N _z can be given a fixed value as required, and the X-direction division fraction N _x and the Y-direction division fraction N _y can be calculated according to formula (2), N _x =212, N _y =28, and the vertical division fraction N _z =10.

Step 4. Generate a flat node;

According to step 3, the X-direction section fraction is N _x , the Y-direction section fraction is N _y , and the Z-direction section fraction is N _z to generate the internal nodes of the plate, the line nodes are obtained from the endpoints of the lines, and the surface nodes are obtained from the opposite edge nodes, The node of the volume is obtained from the opposite node. Nodes are stored in the X, Y, and Z directions first, which is convenient for subsequent steps to construct diamond-shaped elements.

Step 5. Move the node in the X direction;

Move the node in the positive X direction. In the Cartesian coordinate system, the node indices in the three directions of X, Y, and Z are i, j, and k, respectively, where i=1, 2,  , N _x ; j= 1, 2, ..., N _y ; k=1, 2, ..., N _z . Then the moving distance Δx of each node is calculated according to formula (3), and Δx=0.2358 is calculated. As shown in FIG. 5 , the dotted frame I is the node position before the movement, and as shown in FIG. 6 , the dotted frame I′ is the node position after the movement.

Step 6. Calculate the grid of the grooved area in the Z direction;

The number of grids N' _r to be grooved in the Z direction is calculated by formula (4) to obtain N _r '=5.

Step 7. Move the node in the Z direction to make the bottom node of the groove and the groove depth consistent;

Move the node in the Z direction so that the bottom node of the groove is consistent with the groove depth, and the moving distance is calculated according to formula (5).

Δz=0.

Step 8. Calculate the number of units in the Z direction of the defect area;

The number of units in the Z direction of the defect area is represented by _Hz , and _Hz = 1 is calculated according to formula (6).

Step 9. Move the node in the Z direction to make the upper node of the defect area consistent with the height of the defect area;

z三个方向的节点索引分别为i、j、k，对索引i＝N_r-N'_r+H_r的节点进行径向移动，Z方向移动节点使缺陷区上层节点与缺陷区高度一致，移动距离按式(7)计算，计算得Δz_h＝0。In the cylindrical coordinate system, r,

The node indices in the three directions of z are i, j, and k, respectively. Move the node with index i=N _r -N' _r +H _r radially, and move the node in the Z direction to make the upper node of the defect area consistent with the height of the defect area. The moving distance is calculated according to formula (7), and _Δzh =0 is calculated.

Step 10. Construct a rhombus element from nodes;

Eight nodes construct a unit. The index order is shown in Figure 7. The origin of the Cartesian coordinate system is node 1, the point in the y direction is node 2, the point on the xy plane is node 3, and the point in the x direction is node 3 4. The point in the z direction is node 5, the point on the yz plane is node 6, the point in the xyz space is node 7, and the point on the xz plane is node 8. For all nodes stored in the first z, then y, and then x directions, the node index _nodei of the element can be calculated according to equation (8). The constructed diamond-shaped units are stored in the z, then y, and then x directions, which is convenient for subsequent grooving.

When the index j in the Y direction is an even number, it is calculated according to formula (9)

Step 11. Generate four end face nodes;

The negative direction of the X axis is the rear end surface, the positive direction of the X axis is the front end surface, the negative direction of the Y axis is the left end surface, and the positive direction of the Y axis is the right end surface. The nodes on the rear face are obtained by copying the first column of nodes at the beginning of the X direction, and then moving along the X direction. The moving direction is the negative direction of the X axis, and the moving distance can be L _c /2N _x . For the nodes that have moved to the positive X direction, The moving distance after copying can be L _c /N _x . The nodes on the front face are obtained by copying a column of nodes at the end of the X direction and moving, the moving direction is the positive direction of the X axis, and the moving distances can be L _c /2N _x and L _c /N _x . The nodes on the left end face are obtained by copying the first and second columns of nodes at the starting end of the Y-axis direction, and then moving them along the _Y -direction. , the moving distance of the second column of the starting end can be 2b/N _y . The nodes on the right end face are obtained by copying the last two columns of nodes at the end of the Y-axis direction, and then moving them along the Y-direction. The moving direction is the positive direction of the Y-axis. The first column can be moved by b/N _y , and the second column can be moved by 2b /N _y , the generated four end-face nodes are shown in the dotted box in Figure 8.

Step 12. Construct four end face elements from nodes;

A unit is constructed by 8 nodes. For nodes stored in the Z, Y, and X directions first, the node index _nodei of the unit can be calculated according to formula (10), and the four end face elements are shown in Figure 9.

Step 13: Calculate the grid number of grooves in the Y direction;

The grid number of the groove interval in the Y direction is calculated from the groove width and the grid number of a single groove, and can be calculated according to formula (11).

Step 14, set the transition area;

The Y direction index and Z direction index of the groove area unit are respectively determined by the number of groove interval units in the Y direction and the number of groove units in the Z direction, and all units that satisfy the Y direction index and the Z direction index in the unit are set as transition areas.

Step 15: Calculate the number of cells in the Z direction of the melting zone and the number of cells in the width of the melting zone;

The number of elements H _m in the Z direction of the melting zone is calculated from the formula (12).

H _m =N _z -H _z (12)

The number of units N _m across the width of the melting zone is calculated from equation (13).

N _m =NS ₀ (13)

Step 16, set the melting area;

The Y-direction index and Z-direction index of the melting area unit are respectively determined by the number of grooved interval units in the Y direction and the number of grooved units in the Z direction.

Step 17, delete the defective area unit;

Determine the Y-direction index and Z-direction index of the defective area unit by the number of grooved interval units in the Y direction and the number of grooved units in the Z direction unit.

Step 18, output unit and node;

The node and element information of the output mesh can be formatted according to the format requirements of different solvers.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. A flat finite element mesh parametric modeling method for processing diamond patterns by high energy beams is characterized by comprising the following steps:

constructing a rhombohedral grid by using nodes to finish the division of a flat grid containing high-energy beam slot lines;

step two, four end faces around the flat grid are filled;

determining the number of units in the defect area of the high-energy beam slot line according to the proportional relation between the high-energy beam slot line and the width and height directions of the flat plate;

deleting the area grids of the high-energy beam slot line defect area along the width direction and the height direction of the flat plate respectively to complete modeling;

and step four, outputting node and unit information of the grid according to the format requirement of the finite element software.

2. The parametric modeling method for finite element meshes of a plate with a diamond-shaped pattern processed by high energy beams as claimed in claim 1, wherein the length direction of the plate is taken as the X direction, and the specific method of the step one comprises the following steps:

101, calculating X, Y subdivision numbers in a Z direction under a Cartesian coordinate system, and setting the subdivision number in the Z direction;

102, generating nodes according to the X, Y and the subdivision number in the Z direction;

103, moving the node along the positive X direction, so that the connecting line of the moving node and the adjacent node in the Y direction forms a half of the grooving angle with the X direction;

104, determining a grid area of the high-energy beam groove line in the Z direction according to the groove depth, the plate thickness and the Z direction section;

105, moving the node in the Z direction to enable the depth of the node at the bottom of the groove to be consistent with that of the notch groove; meanwhile, moving the node in the Z direction to enable the upper-layer node of the slot line defect area to be consistent with the height of the defect area;

and 106, constructing a diamond unit by using the nodes to obtain a diamond hexahedron grid containing the high-energy beam slot line.

3. The method for modeling a flat finite element mesh with a diamond pattern processed by high energy beams according to claim 2, wherein the specific method in the second step is as follows:

step 201, two end faces in the X direction: copying a starting end row and an ending end row of nodes in the X direction, and respectively moving along the positive direction and the negative direction of the X direction to obtain end surface nodes of two end surfaces; for the nodes which have moved along the X forward direction, the nodes which are copied and moved by the starting end column or the ending end column after copying and moving are collinear;

two end faces in the Y direction: copying two columns of nodes of a starting end and two columns of nodes of an ending end in the Y direction, and respectively moving along the positive direction and the negative direction of the Y direction to obtain end surface nodes of two end surfaces;

and 202, constructing end face units of four end faces by the nodes.

4. The method for parameterizing the finite element mesh of a slab with a diamond-shaped pattern processed by high energy beams of claim 3, wherein the moving method of the step 201 comprises the following steps:

in the X direction: taking L as the moving distance of the starting end column and the ending end column_c/2N_xThe moving distance after copying the node which has moved in the X direction is taken as L_c/N_x，L_cIs the length of the plate, N_xIs the fraction in the X direction;

in the Y direction: the moving distance of the first column at the starting end and the last column at the ending end can be b/N_yThe moving distance of the second row of the starting end and the second row of the ending end is 2b/N_yB is the width of the plate, N_yIs the fraction in the Y direction.

5. The method of parametric modeling of high energy beam machined diamond patterned flat finite element mesh as claimed in claim 3 wherein said step 202 of constructing end face elements from nodes is by: 8 nodes construct a unit, and the nodes and the node index are stored according to the directions of z, y and x_nodeiThe calculation is as follows, i, j, k are node indexes of X, Y, Z directions respectively, N_xIs the fraction in the X direction, N_yIs a fraction in the Y direction, N_zIs the section in the Z direction, and is the section in the Z direction,

6. the method for modeling a flat finite element mesh with a diamond pattern processed by high energy beams according to claim 1, wherein the specific method in the third step is as follows:

step 301, determining a transition area unit according to the number of the notching interval units in the Y direction and the number of the notching units in the Z direction;

step 302, determining a melting area unit according to the number of the interval units of the groove in the Y direction and the number of the groove units in the Z direction;

step 303, determining the defective area unit according to the number of the spacing units for notching in the Y direction and the number of the notching units in the Z direction.

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