CN106951647B - Hexahedral mesh division method for taper thread joint - Google Patents
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Abstract
The invention discloses a hexahedral mesh division method of a taper thread joint, which comprises the steps of carrying out segmentation on matched male and female taper threads in a direction vertical to an axis and in a direction along the axis in finite element software; generating an intersection line as a boundary condition for dividing the grid through the created reference surface and the surface of the model; according to the mesh density, reasonably constructing a plane mesh shape of the end face at the cut part of the effective thread section; aligning grid nodes at the matching surfaces of the male and female connectors by establishing nodes; extracting the surface of the hexahedral mesh drawn by the previous thread as the boundary condition of the mesh drawn by the next thread to ensure the continuity of the mesh; for the grid at the non-thread part, the grid size is increased appropriately. The invention can greatly improve the mesh quality of the taper thread joint, improve the simulation precision and efficiency, and can be popularized and used for hexahedral mesh division of any type of threads.
Description
Technical Field
The invention relates to the technical field of conical threaded joints, in particular to a hexahedral mesh division method of a conical threaded joint, which can accurately analyze the stress distribution condition of the threaded joint under the action of external force on a drill rod.
Background
The taper thread joint is widely adopted in the drilling industry due to good sealing performance, and during the drilling process, a drill rod is easily damaged under the action of friction, pressure, centrifugal force, gravity, torque, bending moment and the like, so that the engineering progress is influenced. Therefore, the threaded joint with good mechanical property is designed, so that the mechanical property of the drill rod is greatly improved, and the loss is reduced. At the present stage, the bench testing machine of the drill rod joint can only load bending moment and torque, and cannot completely simulate real drilling working conditions, so that tooth stress analysis, fatigue analysis, optimization of threads and joint structures of threads by using a finite element simulation technology are adopted.
For finite element simulation analysis, the quality of the mesh directly determines the accuracy and efficiency of the computation. At the present stage, the thread analysis mostly adopts axial symmetry two-dimensional analysis or tetrahedral mesh drawing for analysis, the geometric effect of the three-dimensional model cannot be considered by the axial symmetry two-dimensional analysis, and the accuracy and the operation efficiency cannot be ensured by the tetrahedral mesh analysis. For the threaded connector, because the contact surface and the working environment are complex, the design guidance significance can be achieved only by the high-precision analysis result, the simulation analysis of the threads by adopting the hexahedral mesh with obvious advantages in the aspects of operation precision and efficiency is necessary, and the hexahedral mesh with the mesh nodes matched with the surface aligned can obtain a more accurate result. The 'bolt finite element parametric modeling method capable of realizing hexahedral mesh division' proposed by the university of transportation in western security can only model and grid cylindrical threads by a specific method, cannot be applied to the grid construction of conical threads, cannot also draw hexahedral meshes with aligned grid nodes of male and female connectors, and is extremely complex in method and huge in pretreatment workload.
Therefore, in view of the above-mentioned drawbacks, the present inventors have made extensive studies and designs to provide a hexahedral mesh partitioning method suitable for a taper threaded joint with a small workload, which is significantly significant, by integrating the experience and results of the related industries for many years, so as to overcome the above-mentioned drawbacks.
Disclosure of Invention
The invention aims to provide a hexahedral mesh division method for a conical threaded joint, which improves the conical threaded mesh division quality, reduces the workload of technicians and improves the simulation calculation precision and efficiency.
In order to solve the above problems, the present invention discloses a hexahedral mesh division method for a tapered threaded joint, which is characterized by comprising the following steps:
step 1, performing segmentation on the assembled taper thread joint perpendicular to an axis and along the axis;
step 2, taking a certain effective quarter thread of the taper thread joint after cutting, establishing equidistant nodes on a geometric boundary line parallel to the axis at the end face of the effective thread, establishing a reference surface perpendicular to the axis through the nodes, and establishing an intersection line by using the reference surface and the surface of the thread;
step 3, establishing an equiangular reference surface through an axis;
step 4, establishing a node by using the intersection line established in the step 2, the boundary line of the quarter effective thread and the reference surface established in the step 3;
step 5, creating planar quadrilateral grids on two end faces of the effective quarter thread of the conical threaded joint, wherein the grids take an intersection line as a boundary condition;
step 6, drawing hexahedral mesh cells by taking the geometric relationship among the intersecting lines established in the step 2, the nodes established in the step 4, the meshes established in the step 5 and the effective quarter threads as boundary conditions;
step 7, taking the quarter threads of the taper thread joint matched with the threads selected in the step 3 after the cutting, and repeatedly drawing the hexahedral mesh by using the methods of the step 2 to the step 6;
step 8, repeatedly drawing another conical threaded joint and a hexahedral mesh of three-quarter threads of the conical threaded joint matched with the other conical threaded joint by using the methods of the step 2 to the step 7;
step 9, taking the surface of the drawn hexahedral mesh as the boundary condition of two adjacent sections of threads;
and 10, repeating the step 2 to the step 9, and drawing the hexahedral mesh units of other thread sections and other parts of the joint.
Wherein: in step 1, the assembled taper thread joint is segmented by using finite element software, and the method specifically comprises the following steps: the method comprises the steps of firstly carrying out segmentation vertical to an axis at an effective thread position according to thread pitches, dividing a non-thread position according to structures, and then carrying out segmentation along the axis by using two mutually vertical surfaces.
Wherein: the thread surface of step 3 refers to the face that intersects the established reference plane.
Wherein: in the step 4, the intersection points of the conical threaded joints on the contact surfaces are overlapped, so that the grid nodes with the intersection points as boundary conditions are also overlapped.
Wherein: and (3) aligning the nodes of the grid of the male and female connectors on the contact surface in the step 10.
As can be seen from the above structure, the hexahedral mesh partition method of the tapered threaded joint of the present invention has the following effects:
1. the rapid division is realized, and the practicability is high;
2. the grid quality of the taper thread joint is greatly improved, and the simulation precision and efficiency are improved;
3. the method can be popularized and applied to hexahedral mesh division of any type of threads, and is more widely applicable.
The details of the present invention can be obtained from the following description and the attached drawings.
Drawings
FIGS. 1A-1C illustrate the assembled taper thread joint being split perpendicular to and along the axis;
FIGS. 2A-2D illustrate the steps of establishing an intersection;
FIGS. 3A-3C show steps for establishing a node;
4A-4B illustrate the creation of a planar grid on both end faces of a quarter-effective thread;
FIG. 5 shows a male connector quarter effective thread hexahedral mesh;
FIG. 6 shows a box quarter effective thread hexahedral mesh;
FIG. 7 shows a quarter-threaded hexahedral mesh of the male and female connectors;
FIGS. 8A-8C illustrate an effective hexahedral mesh of the pin and box;
FIG. 9 shows the extraction of the previous valid hexahedral mesh surface as a boundary condition for drawing the next valid thread;
FIG. 10 shows a complete hexahedral mesh of male connectors;
FIG. 11 shows a complete box hexahedral mesh;
FIG. 12 shows a cross-sectional view of a hexahedral mesh of a mating body of a male and female connector;
fig. 13A to 13B are enlarged schematic views showing hexahedral meshes of the mating bodies of the male and female connectors.
Detailed Description
Referring to fig. 1 to 12, a hexahedral mesh division method of a tapered threaded joint of the present invention is shown.
The hexahedral mesh division method of the tapered threaded joint may include the steps of:
1) the assembled taper threaded joint is cut perpendicular to the axis and along the axis, preferably, the taper threaded joint can be a male joint or a female joint, the cutting perpendicular to the axis at the thread matching section is carried out at intervals of one thread pitch, and the taper threaded joint is divided into four parts at equal angles by the cutting along the axis;
2) taking a certain effective quarter thread of a taper thread joint (a male joint or a female joint) after cutting, establishing equidistant nodes on a geometric boundary line parallel to an axis at the end face of the effective thread, establishing a reference surface perpendicular to the axis through the nodes, and establishing an intersection line by using the reference surface and the surface of the thread;
3) establishing an equiangular reference surface through the axis, wherein the number of the reference surfaces depends on the number of grids;
4) establishing a node by using the intersection line established in the step 2), the boundary line of the quarter effective thread and the reference surface established in the step 3); intersection points of the conical threaded joints (male joints or female joints) on the contact surfaces are overlapped, so that grid nodes with the intersection points as boundary conditions are also overlapped;
5) creating planar quadrilateral grids on two end faces of effective quarter threads of a taper thread joint (a male joint or a female joint), wherein the grids take intersecting lines as boundary conditions;
6) and (3) drawing hexahedral mesh cells by taking the geometric relationship among the intersecting lines established in the step 2), the nodes established in the step 4), the meshes established in the step 5) and the effective quarter threads as boundary conditions.
7) Taking one quarter of threads of the taper thread joint (female joint or male joint) matched with the threads selected in the step 3) after cutting, and repeatedly drawing the hexahedral mesh by using the methods of the steps 2) to 6);
8) repeatedly drawing the hexahedral meshes of the three-quarter threads of the other conical threaded joint (the male joint or the female joint) and the conical threaded joint (the female joint or the male joint) matched with the other conical threaded joint by using the methods from the step 2) to the step 7);
9) taking the surface of the drawn hexahedral mesh as the boundary condition of two adjacent sections of threads (joint bodies);
10) and (5) repeating the steps 2) to 9), and drawing the hexahedral mesh grid units of the rest thread sections and other parts of the joint.
The invention will be described in detail below with reference to the drawings by taking a phi 50 drill pipe joint as an example.
Step 1, cutting the taper threaded connector perpendicular to the axis and along the axis. The cutting process is carried out on the matched male connector and the matched female connector at the same time, cutting is carried out on an effective thread section by taking a thread pitch as an interval, and reasonable cutting is carried out on a non-thread section according to the structure. Fig. 1A to 1C show the effect after dicing.
And 2, taking a certain effective quarter thread of the segmented male joint (or female joint), establishing equidistant nodes on a geometric boundary line parallel to the axis at the end face of the effective thread, establishing a reference surface perpendicular to the axis through the nodes, and establishing an intersection line by using the reference surface and the surface of the thread, wherein the intersection line is used as one of boundary conditions for drawing the hexahedral mesh. Fig. 2A to 2D show the process of creating the intersection.
And 3, establishing an equiangular reference surface through the axis, wherein the number of the reference surfaces depends on the size of the grid, and the intersection point of the reference surfaces and the intersection line is used as a node of the grid. Fig. 3A to 3C show a process of creating a node.
And 4, creating a plane quadrilateral grid on two end faces of the effective quarter thread of the male joint (or the female joint). Fig. 4A to 4B illustrate a planar quadrilateral mesh creation process.
And 5, drawing hexahedral mesh grid units by taking geometric boundaries of intersecting lines, nodes, planar quadrilateral meshes and effective quarter threads as boundary conditions. Figure 5 shows the hexahedral mesh as drawn.
And 6, taking the quarter threads of the female connector (or the male connector) matched with the selected quarter threads, and drawing the hexahedral mesh grid unit by taking the geometric boundaries of intersecting lines, nodes, planar quadrilateral meshes and effective quarter threads as boundary conditions. Figure 6 shows the hexahedral mesh as drawn.
And 7, determining the mesh matching state of the male and female connectors shown in the figure 7.
And 8, repeating the steps to draw a complete hexahedral mesh of an effective thread section. Fig. 8A to 8C show a hexahedral mesh of one effective thread segment.
And 9, extracting the surface of the drawn hexahedral mesh of the effective thread section as the boundary condition of two adjacent sections of threads (joint bodies). Fig. 9 shows the surface of the hexahedral mesh from which the effective thread segments have been extracted.
And 10, repeating the steps to draw the hexahedral mesh grid units of other thread sections and other parts of the joint. Fig. 10, 11, 12, 13A to 13B are hexahedral meshes of the male and female connectors.
In step 1, the assembled taper threaded joint is segmented by using finite element software, and the method specifically comprises the following steps: the method comprises the steps of firstly carrying out segmentation vertical to an axis at an effective thread position according to thread pitches, dividing a non-thread position according to structures, and then carrying out segmentation along the axis by using two mutually vertical surfaces.
Wherein the threaded surface of step 3 refers to the face that intersects the established reference plane.
Wherein the nodes of the grid of male and female connectors drawn in step 10 on the contact surface are aligned.
Therefore, the matched male and female taper threads are cut in the direction perpendicular to the axis and along the axis through finite element software; generating an intersection line as a boundary condition for dividing the grid through the created reference surface and the surface of the model; according to the mesh density, reasonably constructing a plane mesh shape of the end face at the cut part of the effective thread section; aligning grid nodes at the matching surfaces of the male and female connectors by establishing nodes; extracting the surface of the hexahedral mesh drawn by the previous thread as the boundary condition of the mesh drawn by the next thread to ensure the continuity of the mesh; for the grid at the non-thread part, the grid size is increased appropriately. The invention can greatly improve the mesh quality of the taper thread joint, improve the simulation precision and efficiency, and can be popularized and used for hexahedral mesh division of any type of threads.
It should be apparent that the foregoing description and illustrations are by way of example only and are not intended to limit the present disclosure, application or uses. While embodiments have been described in the embodiments and depicted in the drawings, the present invention is not limited to the particular examples illustrated by the drawings and described in the embodiments as the best mode presently contemplated for carrying out the teachings of the present invention, and the scope of the present invention will include any embodiments falling within the foregoing description and the appended claims.
Claims (5)
1. A hexahedral mesh dividing method for a tapered threaded joint is characterized by comprising the following steps:
step 1, performing segmentation on the assembled taper thread joint perpendicular to an axis and along the axis;
step 2, taking a certain effective quarter thread of the taper thread joint after cutting, establishing equidistant nodes on a geometric boundary line parallel to the axis at the end face of the effective thread, establishing a reference surface perpendicular to the axis through the nodes, and establishing an intersection line by using the reference surface and the surface of the thread;
step 3, establishing an equiangular reference surface through an axis;
step 4, establishing a node by using the intersection line established in the step 2, the boundary line of the quarter effective thread and the reference surface established in the step 3;
step 5, creating planar quadrilateral grids on two end faces of the effective quarter thread of the conical threaded joint, wherein the grids take an intersection line as a boundary condition;
step 6, drawing hexahedral mesh cells by taking the geometric relationship among the intersecting lines established in the step 2, the nodes established in the step 4, the meshes established in the step 5 and the effective quarter threads as boundary conditions;
step 7, taking the quarter threads of the taper thread joint matched with the threads selected in the step 3 after the cutting, and repeatedly drawing the hexahedral mesh by using the methods of the step 2 to the step 6;
step 8, repeatedly drawing another conical threaded joint and a hexahedral mesh of three-quarter threads of the conical threaded joint matched with the other conical threaded joint by using the methods of the step 2 to the step 7;
step 9, taking the surface of the drawn hexahedral mesh as the boundary condition of two adjacent sections of threads;
and 10, repeating the step 2 to the step 9, and drawing the hexahedral mesh units of other thread sections and other parts of the joint.
2. The hexahedral mesh division method according to claim 1, wherein: in step 1, the assembled taper thread joint is segmented by using finite element software, and the method specifically comprises the following steps: the method comprises the steps of firstly carrying out segmentation vertical to an axis at an effective thread position according to thread pitches, dividing a non-thread position according to structures, and then carrying out segmentation along the axis by using two mutually vertical surfaces.
3. The hexahedral mesh division method according to claim 1, wherein: the thread surface of step 3 refers to the face that intersects the established reference plane.
4. The hexahedral mesh division method according to claim 1, wherein: in the step 4, the intersection points of the conical threaded joints on the contact surfaces are overlapped, so that the grid nodes with the intersection points as boundary conditions are also overlapped.
5. The hexahedral mesh division method according to claim 1, wherein: and (3) aligning the nodes of the grid of the male and female connectors on the contact surface in the step 10.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102332047A (en) * | 2011-10-09 | 2012-01-25 | 西安交通大学 | Bolt finite element parametric modeling method capable of realizing hexahedron grid division |
| CN106202639A (en) * | 2016-06-29 | 2016-12-07 | 北京强度环境研究所 | A kind of MJ bolt and nut finite element grid modeling method |
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| CN102332047A (en) * | 2011-10-09 | 2012-01-25 | 西安交通大学 | Bolt finite element parametric modeling method capable of realizing hexahedron grid division |
| CN106202639A (en) * | 2016-06-29 | 2016-12-07 | 北京强度环境研究所 | A kind of MJ bolt and nut finite element grid modeling method |
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