A free-form surface meshing method for rod end joint stiffness calculation

Abstract

The present invention discloses a free-form surface mesh division method for calculating the stiffness of a rod end joint, comprising the following steps: performing a passivation treatment on a sharp-angled area of ​​the free-form surface, and segmenting the free-form surface using the midpoint of a first arc segment, the intersection of a second arc segment and a first straight line segment, and the midpoint of a third arc segment as basic control points; extending a basic control line from the basic control point toward the rod end joint body, thereby cutting a surface area located inside the free-form surface on a two-dimensional cross section into a plurality of closed or non-closed sub-surface areas through the basic control line; performing a tetrahedral mesh layout on the sub-surface areas to form a full-section mesh layout; the present invention performs a mesh division treatment on the free-form surface including the sharp-angled area, improves the accuracy in the stiffness calculation process of the sharp-angled area through the passivation treatment, and better performs surface area cutting on the free-form surface through the segmentation treatment of the free-form surface, thereby improving the accuracy and calculation efficiency in the subsequent finite element analysis and stiffness calculation process of the free-form surface.

Description

Technical Field

[0001] The invention relates to the technical field of mesh division of finite element analysis, and in particular to a free-form surface mesh division method for calculating the stiffness of a rod end joint. Background Art

[0002] A rod end joint is a flexible connection installed at the end of a rod, including a connecting rod joint, a traction rod joint, and a rotor flexible connection. It is widely used in control and power transmission systems in fields such as rail transit and aerospace. Rod end joints are usually made of a core shaft, a spacer, an external joint, and rubber vulcanization. According to the structural form, they are divided into single-layer rod end joints and multi-layer rod end joints. Among them, multi-layer rod end joints refer to metal rubber vulcanized rod end bearings containing multiple layers of rubber and multiple layers of spacers. Multi-layer rod end joints have better multi-axis load-bearing capacity and can simultaneously withstand large radial loads, axial loads, torsional loads, deflection loads and other composite loads.

[0003] During the development of multi-layer rod end joints, the assessment of the fatigue life of the rod end bearing is a very critical point. The fatigue life of the rod end bearing can be assessed by test method and finite element simulation analysis method. Considering the cycle and cost of the test method, the finite element simulation analysis method is now more and more widely used. In the early pre-research and design stage, the finite element simulation analysis method is used instead of the test test to reduce the number of trial production and tests, improve the one-time design success rate of the rod end bearing, shorten the development cycle of the rod end bearing, and reduce the development cost of the rod end bearing.

[0004] The difficulty in simulation analysis of fatigue life of multi-layer rod end joints lies in the accuracy and efficiency of the analysis. How to ensure the accuracy of calculation results and improve the efficiency of simulation analysis, meshing is particularly important. According to the conventional meshing method, each layer of rubber and each layer of spacer is divided into two-dimensional and three-dimensional grids separately. This method has low meshing efficiency for this type of multi-layer structure rod end bearings, especially some rotor flexible connection rod end bearings have more than thirty layers of rubber and spacers, and it takes a week just to divide the grid. Therefore, conventional meshing methods are difficult to balance the simulation accuracy and efficiency of this type of multi-layer rod end joints. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a free-form surface meshing method for calculating the stiffness of a rod end joint, which solves the problem of insufficient calculation accuracy of the stiffness between the rubber layer and the spacer layer in the rod end joint, resulting in inaccurate simulation analysis data and low efficiency.

[0006] The technical solutions adopted by the present invention to solve the problems of the prior art are as follows:

[0007] A free-form surface meshing method for calculating the stiffness of a rod end joint is provided, comprising: obtaining a two-dimensional cross section and a free-form surface of the rod end joint, wherein the free-form surface comprises a sharp angle region, wherein the sharp angle region comprises at least a first arc segment and a second arc segment intersecting each other, a first straight line segment intersecting the second arc segment, and a third arc segment intersecting the other end of the first straight line segment;

[0008] Performing a passivation process on the sharp corner area of ​​the free-form surface, wherein the passivation process comprises dragging the intersection point of the second arc segment and the first arc segment to the midpoint of the first arc segment;

[0009] The free-form surface is segmented based on the midpoint of the first arc segment, the intersection of the second arc segment and the first straight line segment, and the midpoint of the third arc segment as basic control points;

[0010] A basic control line is extended from the basic control point toward the rod end joint body, so that the surface area located inside the free-form surface on the two-dimensional cross section is cut into a plurality of closed or open sub-surface areas through the basic control line;

[0011] The sub-face regions are respectively subjected to tetrahedral mesh layout to form a full-section mesh layout.

[0012] Further, when extending the basic control line from the midpoint of the first arc segment, the following steps are specifically included:

[0013] Get the midpoint of the first arc segment, the inner endpoint of the free surface, and the midpoint of the second arc segment, connect the midpoint and endpoint of the first arc segment to form a first auxiliary line; connect the midpoint of the second arc segment and the midpoint of the first arc segment to form a second auxiliary line; the first auxiliary line and the second auxiliary line form an angle α, take the midpoint of the first arc segment as the starting point, and make a straight line with an angle of α / 2 as the first basic control line.

[0014] Further, when the basic control line is extended from the midpoint of the third arc segment, the following steps are specifically included:

[0015] Get the midpoint of the third arc segment and the intersection of the third arc segment and the first straight line segment, connect the midpoint of the third arc segment and the intersection of the third arc segment and the first straight line segment to form a third auxiliary line; take the midpoint of the third arc segment as the starting point, and make a fourth auxiliary line perpendicular to the third arc segment; the third auxiliary line and the fourth auxiliary line form an angle β, take the midpoint of the third arc segment as the starting point, and make a straight line with an angle of β / 3 as the second basic control line.

[0016] Furthermore, it also includes taking the endpoint of the second basic control line as the starting point, making a third basic control line parallel to the first straight line segment, and intersecting with the first basic control line.

[0017] Furthermore, it also includes taking the intersection of the second arc segment and the first straight line segment as a starting point, making a fourth basic control line parallel to the second basic control line, and intersecting with the third basic control line.

[0018] Furthermore, it also includes taking the intersection of the first basic control line and the third basic control line as the starting point, connecting the midpoint of the second arc segment to form a fifth auxiliary line; taking the intersection of the third basic control line and the fourth basic control line as the starting point, connecting the midpoint of the fifth auxiliary line and extending it to the first basic control line to form a fifth basic control line.

[0019] Preferably, before the surface region located inside the free-form surface on the two-dimensional cross section is cut into a plurality of closed or open sub-surface regions by the basic control line, the auxiliary line is deleted.

[0020] Furthermore, it also includes a second straight line segment, which intersects with the first circular arc segment.

[0021] Furthermore, the passivation process includes: dragging the intersection point of the second straight line segment and the first arc segment to the end point of the first arc segment located outside the free surface.

[0022] The beneficial effects are as follows:

[0023] The present invention performs meshing processing on free-form surfaces, especially free-form surfaces including sharp-angle areas, improves the accuracy of the stiffness calculation process of the sharp-angle areas through passivation processing, and better performs face area cutting on the free-form surfaces through segmentation processing, making the meshing of the free-form surfaces more reasonable, further improving the accuracy of the free-form surfaces in subsequent finite element analysis and stiffness calculation processes, and improving the calculation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of dividing the free profile of the rod end joint in this embodiment;

[0025] Figure 2 This is a schematic diagram of the rod end joint structure of this embodiment;

[0026] Figure 3 This is an enlarged view of the free surface of the rod end joint rubber and the spacer structure of this embodiment;

[0027] Figure 4 This is the free-profile line segment position diagram of this embodiment;

[0028] Figure 5 This is a diagram of the position of the free-form surface segments in this embodiment;

[0029] Figure 6 This is a schematic diagram of obtaining auxiliary lines of free-form surfaces in this embodiment;

[0030] Figure 7 This is a schematic diagram of obtaining the basic control line of the free-form surface of this embodiment;

[0031] Figure 8 This is a schematic diagram of meshing of the free-form surface without deleting auxiliary lines in this embodiment;

[0032] Fig. 9 Schematic diagram of free-form surface mesh division in this embodiment. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific implementation methods. In this embodiment, the sharp corner area processing and the meshing method are described in conjunction with the free surface state formed between the rubber layer and the spacer in the specific rod end joint.

[0034] like Figures 1 to 3 As shown, this embodiment provides a free-form surface meshing method for calculating the stiffness of a rod end joint, including: obtaining a two-dimensional cross section C of the rod end joint and an enlarged view C' of the free-form surface.

[0035] like Figure 4 As shown, the free-form surface includes a sharp-angle area A. In this embodiment, the sharp-angle area A includes a first arc segment R01 and a second arc segment R02 intersecting each other, a first straight line segment L1 intersecting the second arc segment R02, a third arc segment R03 intersecting the other end of the first straight line segment L1, and a second straight line segment L2 intersecting the first arc segment R01.

[0036] like Figure 5 As shown, the sharp corner area A of the free surface is blunted, including dragging the intersection of the second arc segment R02 and the first arc segment R01 to the midpoint P1 of the first arc segment R01; dragging the intersection of the second straight line segment L2 and the first arc segment R01 to the outer end point P2 of the first arc segment R01 on the free surface.

[0037] In this embodiment, the free-form surface is segmented based on the midpoint P1 of the first arc segment R01, the intersection P3 of the second arc segment R02 and the first straight line segment L1, and the midpoint P4 of the third arc segment R03 as basic control points;

[0038] A basic control line is extended from the basic control point toward the rod end joint body, thereby cutting the surface area located inside the free surface on the two-dimensional cross section into multiple closed and open sub-surface areas through the basic control line; in this embodiment, the direction of the rod end joint body is to the left.

[0039] The sub-face regions are respectively tetrahedron-meshed to form a full-section mesh layout.

[0040] The specific division method in this embodiment is as follows:

[0041] 1. When the basic control line is extended from the midpoint P1 of the first arc segment R01, the following steps are specifically included:

[0042] like Figure 6-7 As shown, obtain the midpoint P1 of the first arc segment R01 and the inner endpoint P5 of the free surface, and the midpoint P6 of the second arc segment R02, connect the midpoint P1 and endpoint P5 of the first arc segment R01 to form a first auxiliary line L1'; connect the midpoint P6 of the second arc segment R02 and the midpoint P1 of the first arc segment R01 to form a second auxiliary line L2'; the first auxiliary line L1' and the second auxiliary line L2' form an angle α, take the midpoint P1 of the first arc segment R01 as the starting point, and make a straight line with an angle of α / 2 as the first basic control line B1.

[0043] 2. If Figure 6-7 As shown, when the basic control line is extended from the midpoint P4 of the third arc segment R03, the following steps are specifically included:

[0044] Get the midpoint P4 of the third arc segment R03 and the intersection of the third arc segment R03 and the first straight line segment L1, connect the midpoint P4 of the third arc segment R03 and the intersection P7 of the third arc segment R03 and the first straight line segment L1 to form a third auxiliary line L3'; take the midpoint P4 of the third arc segment R03 as the starting point, and make a fourth auxiliary line L4' perpendicular to the third arc segment R03; the third auxiliary line L3' and the fourth auxiliary line L4' form an angle β, take the midpoint P4 of the third arc segment R03 as the starting point, and make a straight line with an angle of β / 3 as the second basic control line B2.

[0045] 3. If Figure 7 As shown, with the endpoint P8 of the second basic control line B2 as the starting point, a third basic control line B3 is made parallel to the first straight line segment L1 and intersects with the first basic control line B1 at P9.

[0046] 4. If Figure 7 As shown, with the intersection point P10 of the second arc segment R02 and the first straight line segment L1 as the starting point, a fourth basic control line B4 parallel to the second basic control line B2 is made to intersect with the third basic control line B3.

[0047] 5. If Figures 7-9 As shown, taking the intersection point P9 of the first basic control line B1 and the third basic control line B3 as the starting point, connecting the midpoint P6 of the second arc segment R02, a fifth auxiliary line L5' is formed; taking the intersection point P11 of the third basic control line B3 and the fourth basic control line B4 as the starting point, connecting the midpoint of the fifth auxiliary line L5' and extending to the first basic control line B1, a fifth basic control line B5 is formed.

[0048] like Figures 7-9As shown, in this embodiment, the basic control lines B1 to B5 cut the surface area located inside the free-form surface on the two-dimensional cross section into multiple closed sub-surface areas, delete the auxiliary lines, and complete the meshing of the free-form surface.

[0049] Obviously, the above embodiments are merely examples for clearly explaining the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the protection of the claims of the present invention.

Claims

1. A free-form surface meshing method for calculating the stiffness of a rod end joint, characterized in that: include: Acquire a two-dimensional cross section and a free-form surface of the rod end joint, wherein the free-form surface includes a sharp angle area, and the sharp angle area includes at least a first arc segment and a second arc segment intersecting each other, a first straight line segment intersecting the second arc segment, and a third arc segment intersecting the other end of the first straight line segment; Performing a passivation process on the sharp corner area of ​​the free-form surface, wherein the passivation process comprises dragging the intersection point of the second arc segment and the first arc segment to the midpoint of the first arc segment; The free-form surface is segmented based on the midpoint of the first arc segment, the intersection of the second arc segment and the first straight line segment, and the midpoint of the third arc segment as basic control points; A basic control line is extended from the basic control point toward the rod end joint body, so that the surface area located inside the free-form surface on the two-dimensional cross section is cut into a plurality of closed or open sub-surface areas through the basic control line; The sub-face regions are respectively subjected to tetrahedral mesh layout to form a full-section mesh layout.

2. The free-form surface meshing method for calculating the rod end joint stiffness according to claim 1, characterized in that: When the basic control line is extended from the midpoint of the first arc segment, the following steps are specifically included: Get the midpoint of the first arc segment, the inner endpoint of the free surface, and the midpoint of the second arc segment, connect the midpoint and endpoint of the first arc segment to form a first auxiliary line; connect the midpoint of the second arc segment and the midpoint of the first arc segment to form a second auxiliary line; the first auxiliary line and the second auxiliary line form an angle α, take the midpoint of the first arc segment as the starting point, and make a straight line with an angle of α / 2 as the first basic control line.

3. The free-form surface meshing method for calculating the rod end joint stiffness according to claim 1, characterized in that: When the basic control line is extended from the midpoint of the third arc segment, the following steps are specifically included: Get the midpoint of the third arc segment and the intersection of the third arc segment and the first straight line segment, connect the midpoint of the third arc segment and the intersection of the third arc segment and the first straight line segment to form a third auxiliary line; take the midpoint of the third arc segment as the starting point, and make a fourth auxiliary line perpendicular to the third arc segment; the third auxiliary line and the fourth auxiliary line form an angle β, take the midpoint of the third arc segment as the starting point, and make a straight line with an angle of β / 3 as the second basic control line.

4. The free-form surface meshing method for calculating the rod end joint stiffness according to claim 3, characterized in that: It also includes taking the endpoint of the second basic control line as a starting point, making a third basic control line parallel to the first straight line segment, and intersecting with the first basic control line.

5. The free-form surface meshing method for calculating the rod end joint stiffness according to claim 4, characterized in that: It also includes taking the intersection of the second arc segment and the first straight line segment as a starting point, making a fourth basic control line parallel to the second basic control line, and intersecting with the third basic control line.

6. The free-form surface meshing method for calculating the rod end joint stiffness according to claim 5, characterized in that: It also includes taking the intersection of the first basic control line and the third basic control line as the starting point, connecting the midpoint of the second arc segment to form a fifth auxiliary line; taking the intersection of the third basic control line and the fourth basic control line as the starting point, connecting the midpoint of the fifth auxiliary line and extending it to the first basic control line to form a fifth basic control line.

7. The free-form surface meshing method for calculating the rod end joint stiffness according to any one of claims 1 to 6, characterized in that: Before cutting the surface area located inside the free-form surface on the 2D section into multiple closed or open sub-surface areas using the basic control lines, delete the auxiliary lines.

8. The free-form surface meshing method for calculating the stiffness of a rod end joint according to any one of claims 1 to 6, characterized in that: It also includes a second straight line segment, which intersects with the first circular arc segment.

9. The free-form surface meshing method for calculating the rod end joint stiffness according to claim 8, characterized in that: The passivation process includes: dragging the intersection point of the second straight line segment and the first arc segment to the end point of the first arc segment located outside the free surface.

Images