Method for dividing flange bolt hexahedron finite element mesh

Abstract

The invention discloses a method for dividing a hexahedron finite element grid of a flange bolt. The method comprises the steps that S01, an image of characteristic parameters of the flange bolt is obtained, finite element modeling is conducted on the flange bolt, and the flange bolt is divided into a nut area, a flange area and a screw area in the axial direction; s02, stretching is carried out in the axial direction of the flange bolt according to the edge of the nut area and the outer diameter line of the screw rod area, and segmentation treatment on the nut area is achieved; s03, integrally segmenting the flange bolt in the axial direction of the flange bolt, and enabling the number of segmented units to be the same as the number of edges of the nut area; and S04, a specific plane is selected to conduct penetrating segmentation on the screw rod area, the flange bolt is divided into 4N hexahedral grid units, and N is the number of the edges of the nut area. By means of the method, the mesh generation speed is increased, the modeling efficiency of the bolt hexahedral mesh is improved, the mesh generation precision is guaranteed, and the finite element analysis result is more accurate and reliable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of finite element modeling method, and particularly relates to a method for dividing a hexahedral finite element grid of a flange bolt. BACKGROUND

[0002] Bolt connection is widely used in various mechanical structures due to low cost, convenient installation and removal, and beautiful appearance, and the connection performance directly affects the overall performance of the entire mechanical system.

[0003] Finite element simulation plays a key role in bolt pretightening force prediction, bolt loosening detection, and thread root stress concentration analysis. At present, the existing technology divides the thread part of the bolt into a finite element hexahedral grid modeling mode to simulate the geometric effect of the thread cooperation of the screw rod and the nut. Although these finite element modeling methods accurately simulate the thread part, the finite element grid modeling process is complex and time-consuming, and a modeling method needs to be developed again for different types of threads. Moreover, the existing finite element analysis does not consider the interaction between the bolt head and the fastened part, the structural strength of the bolt head, and the structural stiffness and strength near the bolt hole of the fastened part, which affects the quality of the analysis.

[0004] However, due to the complex geometric characteristics of the bolt and the nut, it is difficult to balance speed and accuracy when dividing the finite element grid. How to improve the grid division speed and quality has become a difficult problem to be solved in bolt finite element analysis. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a method for dividing a hexahedral finite element grid of a flange bolt, which aims to solve the technical problem of how to improve the division speed and accuracy during the finite element analysis of the bolt.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a method for dividing a hexahedral finite element grid of a flange bolt includes the following steps:

[0007] S01: obtaining an image of the characteristic parameters of the flange bolt, performing finite element modeling on the flange bolt, and dividing the flange bolt into a nut area, a flange area, and a screw rod area along the axial direction;

[0008] S02: performing cutting processing on the nut area by stretching along the axial direction of the flange bolt according to the edge of the nut area and the outer diameter line of the screw rod area;

[0009] S03: performing overall cutting on the flange bolt along the axial direction, so that the number of cut units is the same as the number of edges of the nut area;

[0010] S04: a specific plane is selected to cut through the screw rod area, so that the flange bolt is divided into 4N hexahedral grid units, where N is the number of edges of the nut area.

[0011] Further, the step S02 comprises:

[0012] S021: the first cutting treatment of the nut area is implemented by stretching the flange bolt along the axial direction according to the edges of the nut area;

[0013] S022: the second cutting treatment of the nut area is implemented by stretching the flange bolt along the axial direction according to the outer diameter line of the screw rod area;

[0014] wherein the stretching height of the first cutting treatment is less than the height of the nut area, and the stretching height of the second cutting treatment is equal to the height of the nut area.

[0015] Further, the step S03 comprises:

[0016] S031: the end points at the upper and lower ends of an axial plane of the nut area are selected to construct a cutting surface, and the flange bolt is cut as a whole using the cutting surface;

[0017] S032: the end points at the upper and lower ends of adjacent axial planes of the nut area are sequentially selected to construct a cutting surface, until the constructed cutting surface coincides with the cutting surface of step S031; the flange bolt is cut as a whole using each constructed cutting surface.

[0018] Further, in the step S04, the specific plane is the bottom surface of the flange area.

[0019] Further, in the step S04, the specific plane is a plane formed by the outer diameter line formed by the intersection of the flange area and the screw rod area.

[0020] Further, in the step S04, the specific plane is a plane formed by connecting the edge points of at least three flange units in the plurality of flange units formed by cutting the flange area using the cutting surfaces.

[0021] Further, the nut area is any one of a triangular head nut area, a quadrangular head nut area, a pentagonal head nut area, and a hexagonal head nut area.

[0022] The beneficial effects of the present application are that: compared with the prior art, the method for dividing the flange bolt hexahedral finite element grid in the present application realizes the rapid division of the flange bolt hexahedral finite element grid through the following steps: obtaining the image of the flange bolt characteristic parameter, performing finite element modeling on the flange bolt, and dividing the flange bolt eye into the nut area, the flange area, and the screw rod area, dividing the feature area according to the different structural characteristics of the nut area, the flange area, and the screw rod area, then cutting the nut area in advance, then cutting the entire flange bolt, and finally cutting the screw rod area through. In this way, the flange bolt hexahedral finite element grid is rapidly divided. This method not only improves the speed of grid division and the modeling efficiency of the bolt hexahedral grid, but also ensures the accuracy of grid division, so that the results of finite element analysis are more accurate and reliable. Through the local-global-local cutting method of the flange bolt, the problem of model discontinuity caused by missing element common nodes in the modeling process is effectively avoided. In addition, this division method can meet the requirements of different commercial finite element software and effectively improve the modeling efficiency.

[0023] Other advantages, objects, and features of the present application will be set forth in the following specification and will be apparent to those skilled in the art from the teachings of the present application. The objectives and other advantages of the present application will be realized and attained by the structure particularly pointed out in the specification. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to make the purposes, technical solutions and beneficial effects of the present application clearer, the present application provides the following drawings for illustration:

[0025] Figure 1 A flowchart of a method for dividing a flange bolt hexahedral finite element grid according to an embodiment of the present application is shown in the figure.

[0026] Figure 2 A structure diagram of selecting an axial cutting surface for a flange bolt according to an embodiment of the present application is shown in the figure.

[0027] Figure 3 A structure diagram of cutting a flange bolt with the selected axial cutting surface according to an embodiment of the present application is shown in the figure.

[0028] Figure 4 A structure diagram of selecting an axial tensile surface for a flange bolt according to an embodiment of the present application is shown in the figure.

[0029] Figure 5 A structure diagram of cutting a flange bolt with the selected axial tensile surface according to an embodiment of the present application is shown in the figure.

[0030] Figure 6A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure;

[0031] Figure 7 A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure;

[0032] Figure 8 A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure;

[0033] Figure 9 A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure;

[0034] Figure 10 A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure;

[0035] Figure 11 A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure;

[0036] Figure 12 A structure diagram of selecting a cutting surface for a cap area in a flange bolt according to an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0037] As shown in the figure, the embodiment proposes a method for dividing a hexahedral finite element mesh of a flange bolt, including the following steps: Figure 1

[0038] S01: Obtain an image of a characteristic parameter of a flange bolt, perform finite element modeling on the flange bolt, and divide the flange bolt into a cap area, a flange area, and a screw rod area along an axial direction;

[0039] S02: Perform cutting processing on the cap area by stretching along the axial direction of the flange bolt according to the edges of the cap area and the outer diameter line of the screw rod area;

[0040] S03: Perform overall cutting on the flange bolt along the axial direction, so that the number of cutting units is the same as the number of edges of the cap area;

[0041] S04: Select a specific plane to perform through cutting on the screw rod area, so that the flange bolt is divided into 4N hexahedral mesh units, where N is the number of edges of the cap area.

[0042] ​In the present application, by acquiring the image of the flange bolt characteristic parameter, the flange bolt is modeled by finite element, and the flange bolt eye is divided into the nut area, the flange area, and the screw rod area. According to the different structural characteristics of the nut area, the flange area, and the screw rod area, the characteristic area is divided. Then the nut area is cut, the whole flange bolt is cut, and the screw rod area is cut again. In this way, the hexahedral finite element mesh of the flange bolt is quickly divided. This method not only improves the speed of mesh division and the modeling efficiency of the bolt hexahedral mesh, but also ensures the accuracy of mesh division, so that the result of finite element analysis is more accurate and reliable. By the local-global-local cutting method of the flange bolt, the problem of model discontinuity caused by missing element common nodes in the modeling process is effectively avoided. In addition, this division method can meet the needs of different commercial finite element software and effectively improve the modeling efficiency.

[0043] In the present application, by using the division method in ABAQUS finite element software, the modeling can be completed in one minute through the above steps, which has a faster modeling efficiency.

[0044] Further, the step S02 comprises:

[0045] S021: the first cutting treatment of the nut area is realized by stretching the flange bolt along the axial edge of the nut area;

[0046] S022: the second cutting treatment of the nut area is realized by stretching the flange bolt along the axial outer diameter line of the screw rod area;

[0047] The stretching height of the first cutting treatment is less than the height of the nut area, and the stretching height of the second cutting treatment is equal to the height of the nut area.

[0048] In the present application, the nut area is first cut by stretching the flange bolt along the axial edge of the nut area to a certain height. Then the second cutting treatment of the nut area is realized by stretching the flange bolt along the axial outer diameter line of the screw rod area. By controlling the stretching height of the first and second cutting treatments, the characteristic area of the nut area is divided. In addition, by controlling the stretching height of the first and second cutting treatments, the actual shape of the nut area can be better simulated, the accuracy of finite element analysis can be improved, and the subsequent cutting of the whole flange bolt can be more uniform, avoiding the situation that the local mesh is too large or too small, and further improving the accuracy and efficiency of mesh division.

[0049] Further, the step S03 comprises:

[0050] S031: Select the end points of the axial plane of the nut area at the upper and lower ends to construct a cutting surface, and use the cutting surface to perform overall cutting on the flange bolt;

[0051] S032: Select the end points of the adjacent axial plane of the nut area at the upper and lower ends in turn to construct a cutting surface, until the constructed cutting surface coincides with the cutting surface of step S031; use the constructed cutting surface to perform overall cutting on the flange bolt.

[0052] In the present application, the cutting surface is constructed by selecting the axial plane of the nut area, and the cutting surface is constructed by selecting the adjacent axial plane in turn, so as to realize the cutting of the flange bolt. By performing overall cutting on the flange bolt, the situation of missing or repeated cutting is effectively avoided. The overall cutting method not only improves the speed of grid division, but also ensures the accuracy and modeling efficiency of grid division.

[0053] Further, in the step S04, the screw rod area is cut through by selecting a specific plane, so that the flange bolt can be evenly divided into a plurality of hexahedral grid units. In the present application, the selection of the specific plane can be adjusted according to actual needs. For example, the bottom surface of the flange area, the plane formed by the outer diameter line intersecting the flange area and the screw rod area, or the plane formed by connecting the edge points of at least three flange units formed by cutting the flange area by the cutting surface, etc. can be selected. By flexibly selecting the specific plane, the grid division requirements of different flange bolts can be met, further improving the flexibility and applicability of grid division.

[0054] In addition, in the present application, the specific plane selected in step S04 can be adjusted according to actual needs. For example, when the interaction between the flange area and the screw rod area needs to be analyzed, the plane formed by the outer diameter line intersecting the flange area and the screw rod area can be selected for through cutting. When the structural strength of the flange area needs to be analyzed, the bottom surface of the flange area can be selected for through cutting. This flexible cutting method can meet different analysis requirements and improve the accuracy and reliability of finite element analysis.

[0055] Further, the nut area is any one of a triangular head nut area, a quadrangular head nut area, a pentagonal head nut area, and a hexagonal head nut area. These different shapes of nut areas have their own characteristics and application scenarios. For example, the triangular head nut area may be suitable for situations where space is limited or special fastening effect is required; the quadrangular head nut area may provide more stable fastening performance and be suitable for scenarios where high fastening force is required; the pentagonal head nut area and the hexagonal head nut area may exhibit better stability and durability when subjected to large torque. In specific implementation, the appropriate shape of the nut area can be selected according to the specific application scenario and performance requirements of the flange bolt to ensure the accuracy and applicability of finite element grid division.

[0056] In the modeling of ABAQUS finite element software, as shown in the following Table 1, the C3D8R unit type is adopted, and the number of units is only 21% of the C3D4 unit type; if C3D10M unit is used to improve the calculation accuracy, the number of nodes is 5.93 times of the C3D8R unit.

[0057] Table 1 Comparison table of different modeling methods

[0058]

[0059] Example one:

[0060] In this application, the hexagonal head nut area is taken as an example to illustrate the division method of the application. Please refer to Figures 2 to 12 , the specific division method is as follows:

[0061] Firstly, in the pre-processing module of the finite element software, the flange bolt 3D model is imported, and the six edges of the nut area (such as Figure 2 indicated by the red line in the middle) are selected for axial cutting, and the cutting effect is as shown in Figure 3 (red surface is the cutting common surface), then the outer diameter line of the screw rod area in the flange bolt (such as Figure 4 indicated) is selected for axial stretching cutting processing of the nut area, and the effect after cutting is as shown in Figure 5 (red surface is the cutting common surface);

[0062] Further, as shown in Figure 6 , select two diagonal points at the top of the nut area, and the other end point of the edge where one of the points is located (such as Figure 6 three red points), select the plane composed of the three points to cut the entire flange bolt, and the effect after cutting is as shown in Figure 7 , then, the end points at the upper and lower ends of the adjacent axial plane of the nut area are selected in turn to construct the cutting surface, and the flange bolt formed after three times of cutting is as shown in Figure 8 ;

[0063] Subsequently, as shown in Figures 9-11 , select the lower bottom surface of the flange bolt (such as Figure 9 indicated) to cut through the screw rod in the form of a surface; or select three points (such as Figure 10 three red points in the middle) on the lower bottom surface of the flange bolt flange to cut through the screw rod in the form of a plane; or select the edge (such as Figure 11 red circle) intersecting the screw rod area in the flange area to cut through the screw rod area in the form of a closed line. As shown in Figure 12 , through the implementation of the above cutting steps, the flange bolt model of the hexagonal head can be cut into 24 hexahedral grid units.

[0064] In the present application, by the modeling method, the operation complexity of modeling in some finite element software is effectively solved, and the problem of model discontinuity caused by missing common nodes of elements in the modeling process is avoided; and by the division method, different commercial finite element software can be met, and the modeling efficiency is effectively improved.

[0065] Embodiment two:

[0066] In another embodiment of the present application, the four-cornered head nut area is taken as an example for illustration. First, the 3D model of the flange bolt is imported into the pre-processing module of the finite element software, and the four edges of the nut area are selected for axial division. Then, the outer diameter line of the screw rod area in the flange bolt is selected to perform axial stretching division on the nut area. Next, a plane composed of one corner point at the top of the nut area, another corner point on the diagonal line, and two points at the other end of the edge where the two corner points are located, a total of four points, is selected to perform the first division on the entire flange bolt. Then, the end points at the upper and lower ends of the adjacent axial planes of the nut area are sequentially selected to construct the division surface, and the subsequent division is performed on the entire flange bolt until the constructed division surface coincides with the first division surface. Finally, the bottom surface of the flange area or the plane formed by the intersection of the flange area and the screw rod area is selected to perform through division on the screw rod area in the form of a plane, thereby realizing the hexahedral finite element mesh division of the four-cornered head flange bolt model. Through the above method, accurate hexahedral finite element meshes can also be efficiently divided to meet different analysis requirements.

[0067] Embodiment three:

[0068] In still another embodiment of the present application, the nut area is taken as an example to illustrate the five-nut head nut area. First, in the pre-processing module of the finite element software, the three-dimensional model of the flange bolt is imported, and the five edges of the nut area are selected for axial cutting. Subsequently, the nut area is stretched along the axial direction of the flange bolt according to the outer diameter line of the screw rod area, and the second cutting treatment is performed to ensure that the cutting height is consistent with the height of the nut area. Next, select one corner point at the top of the nut area, another corner point at the top of the nut area, and two points at the other end of the edge where the two corner points are located, a total of four points, plus two points at the bottom of the nut area directly connected to the two corner points selected first, a total of six points, to form a plane for the initial cutting treatment of the entire flange bolt. Then, the end points at the top and bottom of the adjacent axial plane of the nut area are selected in turn to construct the cutting surface, and the subsequent cutting of the entire flange bolt is performed until all the constructed cutting surfaces coincide with the initial cutting surface. Finally, according to actual needs, the bottom surface of the flange area, the plane formed by the intersection of the flange area and the screw rod area, or the edge points of at least three flange units formed by the cutting of the flange area by the cutting surfaces can be selected as a specific plane to cut through the screw rod area in a planar manner, thereby achieving hexahedral finite element meshing of the five-nut head flange bolt model. Through the above method, accurate hexahedral finite element meshes can also be efficiently divided, not only improving the speed and efficiency of meshing, but also ensuring the accuracy of meshing, making the results of finite element analysis more accurate and reliable.

[0069] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and detail without departing from the scope defined by the claims of the present application.

Claims

1. A method for dividing a flange bolt hexahedron finite element mesh, characterized in that: The steps include: S01: Obtain an image of the characteristic parameters of the flange bolt, perform finite element modeling on the flange bolt, and divide the flange bolt into a nut area, a flange area, and a screw area along the axial direction; S02: The nut area is divided by stretching along the axial direction of the flange bolt according to the edge of the nut area and the outer diameter line of the screw area; S03: The flange bolt is integrally cut along its axial direction so that the number of cut units is the same as the number of edges in the nut area; S04: Select a specific plane to perform a through-cutting operation on the screw region so that the flange bolt is divided into 4N hexahedral grid units, where N is the number of edges in the nut region.

2. The method for dividing the flange bolt hexahedron finite element mesh according to claim 1, characterized in that: The step S02 includes: S021: Performing a first cutting process on the nut area by stretching the edge of the nut area along the axial direction of the flange bolt; S022: A second cutting process is performed on the nut area by stretching the flange bolt axially along the outer diameter line of the screw area; The stretching height of the first cutting process is smaller than the height of the nut region, and the stretching height of the second cutting process is equal to the height of the nut region.

3. The method for dividing the flange bolt hexahedron finite element mesh according to claim 1, characterized in that: The step S03 includes: S031: Select the upper and lower endpoints of an axial plane in the nut area, construct a cutting surface, and use the cutting surface to cut the flange bolt as a whole; S032: Select the endpoints of the upper and lower ends of the adjacent axial planes of the nut area in sequence to construct a cutting surface until the constructed cutting surface coincides with the cutting surface of step S031; use the constructed cutting surfaces to cut the flange bolt as a whole.

4. The method for dividing the flange bolt hexahedron finite element mesh according to claim 1, characterized in that: In step S04, the specific plane is the bottom surface of the flange area.

5. The method for dividing the flange bolt hexahedron finite element mesh according to claim 1, characterized in that: In step S04, the specific plane is a plane formed by an outer diameter line formed by the intersection of the flange area and the screw area.

6. The method for dividing the flange bolt hexahedron finite element mesh according to claim 3, characterized in that: In step S04, the specific plane is a plane formed by connecting the edge points of at least three flange units among the multiple flange units formed by cutting the flange area with each cutting plane.

7. The method for dividing the flange bolt hexahedron finite element mesh according to claim 1, characterized in that: The nut area is any one of a triangular head nut area, a square head nut area, a pentagonal head nut area, and a hexagonal head nut area.

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