JP2848628B2 - Solid shape block division method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] For a solid shape model created by a CAD system,
Regarding the block division method of the solid shape in the generation of the analysis data for analysis by the finite element method, the purpose of developing the block division process of the plate shape is to enable the automation of the block division process of the solid shape. A graphic data of a solid shape model having is input, a graphic data processing means for classifying the graphic data into end point data, line segment data and arc data, and a closed loop corresponding to each plane using each data forming the same plane. In the block division method including a plate-shaped block dividing unit that forms predetermined plate-shaped block data by dividing line segments and arcs in accordance with the shape of the closed loop, each block is created for each plane. Using the plate-shaped block data, find another plate-shaped block that is paired with one plate-shaped block, Configuring comprises a solid shape block dividing means for checking presence and pair comprising two whether the formation of plate-shaped blocks for connecting the plate-shaped block from the side.

[Industrial applications]

The present invention relates to a solid shape block division method for generating analysis data for analyzing a solid shape model created by a CAD system by a finite element method.

In recent years, in analysis data generation, which is preprocessing for analyzing solid shape models (three-dimensional wireframe models) created by CAD systems using the finite element method, a method that performs high-speed block division and mesh division has been required. I have.

A patent application has already been filed by the same applicant for a block division method for a plate shape model (Japanese Patent Application No. 1-46938 (filed on Feb. 28, 1989), “plate shape block division device”). The present invention develops this technology to enable block division for a solid shape model.

[Conventional technology]

FIG. 6 is a flowchart for explaining the outline of the structural analysis processing by the finite element method.

The model created by the CAD system is divided into plate and solid blocks. Subsequently, input of constraint conditions, load conditions, material conditions, and other boundary conditions at each boundary is performed, and uniform and regular mesh division is performed for each division element. The above processing is the preprocessing related to the generation of the analysis data.

Based on the analysis data generated in this pre-processing, calculate the stress and displacement of each element using the finite element method and perform a stress analysis of the structure, and perform post-processing to output the analysis results To end.

Since the block division in such a flow is an inhomogeneous and irregular division process depending on the model shape,
Conventionally, automation has been difficult.

That is, the operator recognizes a block including triangles and quadrangles to be divided in the plate-shaped block division according to the conventional method, and a block including triangular prisms and quadrangular prisms to be divided in the solid-shaped block division. (6 points for a triangular prism, 8 points for a square prism, and an intermediate point when an arc is included).

Here, an example of the solid shape block to be divided is shown in FIG. FIG. 7 (a) is a triangular prism formed by all side segments, FIGS. 7 (b) and (c) are triangular prisms including a part of a cylinder (less than 180 degrees) on one side, and FIG. 7 (d). Is a quadrangular prism formed by all side segments, FIGS. 7 (e) and 7 (f) are quadrangular prisms each including a part of a cylinder (less than 180 degrees) on one side, FIGS. 7 (g) and 7 (h) Is a quadrangular prism that includes a portion (less than 180 degrees) of a cylinder on two opposite sides. Note that r _{1 to} r ₄ indicate radii.

[Problems to be solved by the invention]

As described above, since the block division processing has many manual operations, for example, when the number of blocks to be divided increases due to a large model or a complicated shape, for example,
The number of vertices requiring input instructions has increased dramatically, and a reduction in efficiency has been unavoidable.

In the invention already applied for a patent, the plate shape model is divided into a triangular or quadrangular region from a closed loop shape obtained by connecting the end points, thereby enabling a plate shape block to be divided by automatic processing. (The gist of which is shown in the description of the embodiments herein).

SUMMARY OF THE INVENTION An object of the present invention is to provide a block dividing method which enables the automation of a solid-shaped block dividing process by developing a plate-shaped block dividing process.

[Means for solving the problem]

 FIG. 1 is a block diagram showing the principle of the present invention.

In the figure, graphic data processing means 11 receives graphic data of a solid shape model having a plurality of end points, and classifies the graphic data into end point data, line segment data, and arc data.

The plate-shaped block dividing means 13 forms a closed loop corresponding to each plane using the data forming the same plane, and performs a predetermined plate-shaped block by dividing a line segment and an arc according to the shape of the closed loop. Create data.

The solid-shaped block dividing means 15 obtains another plate-shaped block to be paired with one plate-shaped block, and determines whether or not the plate-shaped block exists and to connect the two plate-shaped blocks to be paired from the side. Check for formation.

(Operation)

Graphic data processing means 11 and plate-shaped block dividing means
According to 13, predetermined plate shape block data is created corresponding to each plane of the solid shape model.

According to the present invention, the solid-shape block dividing means 15 uses this plate-shape block data to find another plate-shape block that is paired with one plate-shape block, By checking whether or not a plate-shaped block that connects the plate-shaped blocks can be connected from the side, it is possible to divide the fixed-shaped block.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a flowchart for explaining an outline of a solid-shape block division method.

In the CAD system, the graphic data of the three-dimensional wire frame model shown in FIG. 3A is created.

In the plate-shape block division processing, first, end point data, line segment data, and arc data tables are created from the graphic data.

Table 1 is an end point data table. Corresponding to each end point number of the model, its x, y, and z coordinate values, the point (-2.0), the end point (-1.0), and the center point of the arc (+1.
0) A flag indicating a vector (+2.0) in the direction of 3 o'clock or 12 o'clock is set. In the radiuses r ₁ and r ₂ , the coordinates of the center point, the 3 o'clock direction vector, and the 12:00 o'clock direction data are displayed using end point numbers 13 to 15 and 16 to 18.

Table 2 is a line segment data table. Line segments are indicated by end point numbers at both ends thereof, and a flag indicating an initial value (0), deletion (1), and addition (2) is set for each line segment.

Table 3 is an arc data table. The arc is represented by its two end numbers and the end points corresponding to the center points indicating the radii r ₁ and r ₂ , the 3 o'clock direction vector (V1), and the 12 o'clock direction vector (V2). Initial value (0),
Flags indicating deletion (1) and addition (2) are set.

Subsequent to the creation of each table described above, subdivision of line segments and arcs is performed by closed loop processing.

That is, additional end points (19 to 22) shown in Table 1 and FIG. 3 (b) are obtained, and a line segment including them is divided or added (Table 2, flag "2"). Also,
Line segment to be deleted by dividing the line into two (flag "1")
Occurs. In the example shown here, the arc is not divided.

Through this end point, line segment, and arc division processing, plate-shaped block division is performed, and a plate-shaped block table shown in Table 4 is created.

The number of endpoints “3” and “4” indicate a triangle or a quadrangle (here, all quadrangles), and the end point configurations P _{1 to} P ₄ indicate plate-shaped blocks represented by up to four end point numbers.・ The arc types k _{1 to} k ₄ are between the end points (k ₁ is P ₁ −P ₂ , ..., k ₄
Indicates the type of the line segment or arc of P ₄ −P ₁ ) by “1” or “2”.

FIG. 3 (b) is a result (16 divisions) of a plate-shaped block division corresponding to each plane with respect to the three-dimensional wire frame model (solid formation model) shown in FIG. 3 (a). It is a figure corresponding to a certain plate-shaped block table (Table 4).

In the present invention, following the above-described plate-shaped block division processing, solid-shaped block division processing for creating a solid-shaped block table and creating a solid-shaped block table is performed, and corresponding block display becomes possible.

FIG. 4 is a flowchart showing a detailed embodiment of the solid shape block dividing process.

One triangle or a quadrangle is specified from the top of the plate-shaped block table. That is, the plate-shaped block No. is sequentially incremented, and it is determined whether the end point corresponding to the plate-shaped block No. is a triangle or a square according to whether the number of endpoints is “3” or “4”. To specify.

Hereinafter, when one plate-shaped block is square,
A method of forming a solid block that will be a quadrangular prism will be described. The same applies to a method of forming a solid-shape block serving as a triangular prism.

Basically, the presence or absence of a plate-shaped block facing one plate-shaped block is checked, and a predetermined solid shape block (7th
(Fig.)
First, how to find a plate-shaped block that faces one plate-shaped block (check four sides and check one-sided)
Will be described.

As shown in FIG. 5, for a specified one plate-shaped block (square _{A 0 B 0 C 0 D 0} ), find the plate-shaped rectangular block (side) sharing each side of a plate-shaped block table, Classify into four groups.

That is, a group sharing the side A ₀ B ₀ (the square A ₁ B ₁ B ₀
A ₀ , A ₀ B ₀ B ₂ A ₂ ), a group (square C ₁ ) sharing the side B ₀ C ₀
B ₁ B ₀ C ₀ , C ₀ B ₀ B ₂ C ₂ ), group (square D ₁ C ₁ C ₀ D ₀ , D ₀ C ₀ C ₂ D ₂ ) sharing side C ₀ D ₀ , side D ₀ groups sharing the a ₀ (square _{D 1 a 1 a 0 D 0} , D 0 a 0 a 2 D 2) are classified into.

Next, for each side of the designated rectangle A ₀ B ₀ C ₀ D ₀ , the rectangle display (plate-shaped block configuration) of each group is rearranged so as to be in the same direction.

That is, Becomes

Next, the ,,,, and checking each plate-shaped block that has been changed this arrangement (four sides), respectively _{B 1 (*), C 1} (♯), D 1 ($), A 1 (%) is Since they are common, solid-shaped blocks A ₀ B ₀ C ₀ D ₀ −A ₁ B ₁
C ₁ D ₁ is formed. Similarly, the solid shape block A ₀ B ₀
C ₀ D ₀ −A ₂ B ₂ C ₂ D ₂ is formed.

Here, a rectangle A ₁ facing the designated rectangle A ₀ B ₀ C ₀ D ₀
By checking whether B ₁ C ₁ D ₁ (A ₂ B ₂ C ₂ D ₂ ) is on the plate-shaped block table, it is confirmed whether there is a plate-shaped block facing one plate-shaped block. be able to.

The above processing is the check of the four sides and the check of the one side shown in FIG.

Next, when there is a facing plate-shaped block,
It is checked whether or not the formed solid shaped block corresponds to any of the square pillars shown in FIG. That is, it is determined whether or not a solid block (square prism) is established for one designated plate-shaped block.

When a fixed shape block (square prism) is established, the solid shape block (square prism) data is registered in the solid shape block table.

In addition, in the registration in the solid shape block table, comparison with the already registered solid shape block (for example, comparison of each center of gravity) is performed, and when there is no identical solid shape block, the registration processing is performed.

As the registration format, the lower end face or the left end face is set in advance, and the upper end face or the right end face is set in advance. That is, in the above example, the solid shape block A ₀ B ₀ C ₀ D ₀ −A ₁ B ₁
C ₁ D ₁ is registered as it is without any change in the pre-processing and post-processing, but the solid shape block A ₀ B ₀ C ₀ D ₀ −A ₂ B ₂ C ₂ D ₂ is replaced by A _{2 in the} same processing. It is registered as _{B 2 C 2 D 2 -A 0} B 0 C 0 D 0. The forward and backward movements can be determined by, for example, determining the center of gravity of each plate-shaped block to be faced, and comparing the z-coordinate value (lower end face forward movement) or x-coordinate value (left end face forward movement).

After the registration in the solid shape block table, or when the solid shape block (square prism) is not established or the same solid shape block has already been registered, the registration is not performed and the next square Move to (triangle) designation and repeat the same process.

FIG. 3 (c) is a result (three divisions) of dividing the solid shape block into the three-dimensional wire frame model (solid shape model) of FIG. 3 (a).

Table 5 is a solid-shaped block table corresponding to the plate-shaped block table in Table 4.

The number of end points “6” and “8” indicate a triangular prism or a quadrangular prism (all are square prisms in this case), and the end point configurations P _{1 to} P ₈ indicate solid shape blocks represented by a maximum of eight end point numbers.・
The arc types k _{1 to} k ₄ are between the end points (k ₁ is P ₁ −P ₂ (P ₅ −P ₆ ),
..., k ₄ is indicated by "1" or "2" a line segment or arc of the type of _{P 4 -P 1 (P 8 -P} 1)).

In addition, the end point configuration indicating each solid shape block No.1 to No.3
The arrangement of P _{1 to} P ₈ has been subjected to the above-described rearrangement and pre- and post-processing.

That is, according to the above-described procedure, first, it is determined whether or not a predetermined square pole is established for the plate-shaped block of No. 1 (1-2-8-7) of the plate-shaped block table. Since there is no corresponding quadratic prism whose top or bottom face is .1, the next plate-shaped block
The same check is performed for No. 2 (3-2-8-9).

Plate-shaped block No.2 is plate-shaped block No.7 (10-4
-19-21), and a solid-shaped block No. 1 which is a square prism (FIG. 7 (d)) composed of all side line segments can be formed. Sort (4
−19−21−10) and plate-shaped blocks
No. 2 is registered in advance, and plate-shaped block No. 7 is registered in advance.

In the same manner, the solid shape block No. 2 (a quadrangular prism whose one side is a cylinder (FIG. 7 (f))) and the solid shape block
No.3 (Square prism composed of all side segments (Fig. 7 (d)))
Is registered. In addition, the solid-shaped block No. 3 is based on the plate-shaped block No. 12 (2-20-22-8) in advance, and the sorted plate-shaped block No. 8 (19-5-11-21). Registered later.

〔The invention's effect〕

As described above, according to the present invention, the solid shape block division in the solid shape model (three-dimensional wire frame model) is performed by using plate shape block data obtained by performing plate shape block division corresponding to each plane. , Automatic processing by a computer can be enabled.

Therefore, computer processing of all steps of the structural analysis for the solid shape model can be performed, and operator intervention and labor can be omitted, and processing efficiency can be significantly improved, such as reduction of processing time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a flowchart for explaining the outline of a solid shape block dividing method, FIG. 3 is a diagram showing a block dividing process of a three-dimensional wire frame model, and FIG. FIG. 5 is a flowchart showing a detailed embodiment of the shape block dividing process, FIG. 5 is a diagram for explaining how to find a plate-shaped block facing one plate-shaped block, and FIG. 6 is an outline of a structural analysis process by the finite element method. FIG. 7 is a diagram illustrating an example of a solid-shaped block. In the figure, 11 is a figure data processing means, 13 is a plate-shaped block dividing means, and 15 is a solid-shaped block dividing means.

Claims (1)

(57) [Claims] 1. A graphic data of a solid shape model having a plurality of end points is inputted, and graphic data processing means for classifying the graphic data into end point data, line segment data and arc data, and each of the data forming the same plane And a plate-shaped block dividing means for forming predetermined plate-shaped block data by dividing a line segment and an arc in accordance with the shape of the closed loop by using In the method, using the plate-shaped block data created for each of the planes, another plate-shaped block that is to be paired with one plate-shaped block is obtained, and the presence or absence of the block and the two plate shapes to be paired are determined. A solid-shaped block dividing means for checking whether or not a plate-shaped block connecting the blocks from the side can be formed; Lock division method.