JPH0744525A - Data generating system for finite element analysis - Google Patents

Abstract

PURPOSE:To simply generate mesh data required for desired finite element analysis with excellent operability by providing an input means inputting an optional line element corresponding to a drawing of an analysis object and extracting cross point and line segment data from the line element to generate the mesh data. CONSTITUTION:Optional line elements inputted by a drawing of an analysis object and a mouse or the like are stored in an input data file 2 and the stored data are read by a mesh data generating output section 10 and a cross point calculation section 3 makes cross point calculation processing. The cross point calculation processing extracts cross points of a contour line of the analysis object, cross points between the line elements, and a cross point between a contour line and the line element and the coordinate of each cross point is calculated and the cross point data are obtained and a mesh generating section 4 conducts mesh generation processing. The mesh processing section calculates line segment data from the cross points adjacent on the contour line or the line element and generates mesh data based on the cross point data and the calculated line segment data.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the finite element method (FEM; F).
The present invention relates to a data generation system that generates mesh data used for numerical analysis by the inite Element method.

[0002]

2. Description of the Related Art When performing a numerical analysis by the finite element method, a shape model to be analyzed is divided into blocks, mesh data representing the shape model as numerical data is generated, and the finite element method is applied to this mesh data. The actual calculation is performed. In reality, the number of elements and the number of nodes in the mesh data are restricted due to restrictions such as the memory capacity of the computer used for the calculation and the calculation time. In order to obtain a highly accurate solution under this constraint condition, for example, there is know-how such as narrowing the mesh interval in the stress concentration part to increase the element density.

Conventionally, a preprocessor has been used to create mesh data. In the preprocessor, the emphasis is on the mesh data creation function, and the user creates relatively simple block outline data corresponding to block division by keyboard input of coordinate values, and then interactively performs subdivision operations etc. The mesh data is automatically created by running and determining the final element shape. However, since the drawing function of the preprocessor is inferior, if the outer shape becomes complicated, a lot of work is required for the calculation of the block coordinates and the keyboard input work of the coordinates. Also, when dividing into blocks, the torus part (internal loop) is inside.
Should not be included.

In Japanese Laid-Open Patent Publication No. 3-75970, a dividing line represented by a straight line is designated for a block, and the intersection of the contour line of the block and the dividing line, the internal loop in the block and the dividing line. A method is disclosed in which the intersections and the intersections of the dividing lines are calculated, and the intersections are sorted for each outline to extract the triangular elements or the quadrilateral elements by brute force. According to this method, mesh data can be generated without being aware of the inner loop in the block.

[0005]

In the above-mentioned conventional method for generating mesh data, it is necessary to calculate the block coordinates and input the coordinates on the keyboard by hand, which increases the amount of work and requires know-how for mastering the preprocessor. There is a problem in that In addition, JP-A-3
In the one disclosed in Japanese Patent Publication No. -75970, it is difficult to change the element density in the same block, and in order to perform a desired finite element method analysis, block division must be performed finely, and the work is complicated. There is a problem that

An object of the present invention is to provide a mesh data generation system which is excellent in operability and can easily generate mesh data necessary for performing a desired finite element method analysis.

[0007]

A data generation system for finite element method analysis according to the present invention calculates an intersection between the line means and an input means for inputting an arbitrary line element corresponding to a drawing of an object to be analyzed. And intersection data calculating means for calculating intersection data, mesh data generation means for calculating line segment data from the intersections adjacent to the line element, and mesh data for generating mesh data from the line segment data and the intersection data, and the mesh And output means for outputting data.

[0008]

[Function] Since the input means for inputting an arbitrary line element corresponding to the drawing of the object to be analyzed is provided and the intersection point and line segment data are extracted from this line element to generate the mesh data, the operability is excellent, The element density of the mesh can be easily changed as needed. Here, the line element is not limited to a straight line but includes a curved line, and includes a line element directly input by an arbitrary pointing device such as a mouse or a drag ball.

Any input means may be used as long as it can input an arbitrary line element corresponding to the drawing of the object to be analyzed. For example, a display section for displaying the drawing of the object to be analyzed. A line element for reading the drawing of the analysis object to which a line element is added, or a line input element for sequentially inputting a line element to the drawing displayed on the display unit It is possible to use an image reading means for extracting the. Specifically, a CAD device is shown. The analysis target is designed using the CAD device, the analysis target is displayed on the display of the CAD device based on the design data, and then a pointing device such as a mouse. You can enter the line element by hand using. If design data (graphic data) of the analysis object is available, the data may be read and displayed on the display. Specifically, the one shown in Fig. 2 is a combination of a scanner and an image processing device.A drawing with a line element added is read by a scanner, and the line element is read from the image data read by the image processing device. Just extract it.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a finite element method analysis system according to an embodiment of the present invention. This system is configured to further perform numerical analysis by the finite element method after creating mesh data.

A CAD device 1 having a display is provided. The CAD device 1 is used for designing an analysis target and reading graphic data of the analysis target.
An arbitrary line element used for generating mesh data is configured to be input by a mouse or the like in a state where the drawing of the analysis target is displayed on the display. In this case, line elements input with a mouse or the like are sequentially displayed on the display so as to overlap with the drawing of the analysis target. The drawing of the analysis object and the input line element are stored in the input data file 2.

A mesh data generation / output unit 10 for generating mesh data from the data stored in the input data file 2 is provided. Mesh data generation output unit 1
0 is an intersection point calculation unit 3 that performs an intersection point calculation process by referring to the input data file 2, a mesh generation unit 4 that generates mesh data based on the calculation result of the intersection point calculation unit 3, and the generated mesh data is a mesh. The mesh output unit 5 outputs the data file 6. The intersection calculation unit 3 determines the intersections of the outlines, the intersections of the line elements, and the outlines with respect to the lines (hereinafter referred to as outlines) forming the drawing of the analysis target and the line elements input as described above. It is configured to extract the intersections with the line elements, calculate the coordinates of the intersections, and use them as the intersection data. A known method is used for searching the intersection and calculating the coordinates of the intersection. The mesh generation unit 4 calculates line segment data from intersections that are adjacent to each other on the outline or line element, and generates mesh data from the intersection point data and the calculated line segment data. Here, the line segment data corresponds to a mesh boundary line (element boundary line).

As a method of generating mesh data in the mesh generating unit 4, for example, the innermost "closed region" element is recognized using the intersection and the line segment data, and the node number is counterclockwise. There is a method of confirming the existence and determining the individual elements. This generation method is
A huge amount of complicated data needs to be searched, sorted, and registered, but bidirectional search for which element boundary line an intersection is on, and which element boundary line on the contrary includes which intersection By adopting an object structure that enables the above and adopting a hash algorithm, it is possible to carry out with realistic memory usage and search time.

A condition input section 7 for inputting the mesh data stored in the mesh data file 6 is provided. The condition input unit 7 is where various parameters necessary for the finite element method analysis, such as load conditions and boundary conditions, are input. The output side of the condition input unit 7 is provided with a finite element method analysis calculation unit 8 that actually performs the numerical operation of the finite element method analysis, and the analysis result obtained by the finite element method analysis calculation unit 8 is The data is output to the analysis result file 9.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

First, in the CAD device 1, an analysis target is designed or graphic data of the analysis target is read, and a line element used for creating mesh data is input while displaying a drawing of the analysis target on the display. To do. A mouse attached to the CAD device 1 is used for inputting the line elements. As the line element, there are a straight line designated by two end points, a spline curve, a circular arc, or a free curve formed by a locus of a mouse. At this time, a large number of line elements are drawn in the region where the element density is desired to be high in the mesh data, and line elements are drawn sparsely in the region where the element density is kept low. The line element data input in this manner is stored in the input data file 2 together with the graphic data of the analysis target.

Next, the data stored in the input data file 2 is read by the mesh data generation / output unit 10 (step 101), and the intersection calculation unit 3 performs the intersection calculation process based on the read data (step 101). 102). In the intersection point calculation process, intersection points between contour lines of the object to be analyzed, intersection points between line elements, and intersection points between contour lines and line elements are extracted, coordinates of these intersection points are calculated, and intersection point data is obtained. Then, based on the result of the intersection calculation processing,
Mesh generation processing is performed by the mesh generation unit 4 (step 103). In the mesh generation process, line segment data is calculated from the intersection points that are adjacent to each other on the outline or line element, and the mesh data is generated as described above from the intersection point data and the calculated line segment data. At this time, when the line segment data between certain intersections is extracted, the data in the corresponding section of the line element corresponding to the line segment data is deleted to avoid malfunction when the memory capacity is insufficient. You can And this mesh data is
The mesh data file 6 by the mesh output unit 5
(Step 104).

After that, the mesh data file 6 is read into the condition input unit 7, various parameters are set in the condition input unit 7, and the finite element method analysis calculation unit 8 performs actual numerical analysis calculation. Then, the analysis result obtained by the finite element method analysis calculation unit 8 is the analysis result file 9
Stored in.

Next, the intersection calculation process and the mesh generation process will be described with reference to actual examples. For example, CAD device 1
In, it is assumed that the line element shown in FIG. 3A is input. Each line element is represented by a curve 21. At this stage, the intersection of the curves 21 on the display of the CAD device 1 is not recognized as the intersection. By performing the intersection calculation processing on such a line element, the intersection 22 is recognized and the coordinates of the intersection 22 are calculated. The intersection 22 is a node in the mesh data. Then, by performing mesh generation processing, the curve 21
The element boundary line (line segment data) 23 that connects the intersections 22 with each other is obtained, and each element 24 is extracted. This state is shown in FIG. 3 (b). The element boundary line 23
Is defined as connecting the intersections 22 with each other, so that the whisker-shaped portion of the original curve 21 is ignored. Further, depending on how the curve 21 is drawn, triangular elements or quadrangular elements can be arbitrarily generated as shown in the drawing.

Further, an actual example will be described. FIG. 4A is a diagram showing an example of the analysis object. This analysis object is
It is divided into a plurality of blocks 31 (block division lines are shown by dotted lines), and inside some blocks 31, an inner loop (torus portion) 32 exists. FIG. 4B shows a line element appropriately input to the object to be analyzed using the CAD device 1. Line elements are predominantly added to the stress concentration portion around the inner loop 32. According to this embodiment, as shown in this figure,
The mesh can be set arbitrarily according to the analyst's wishes.

Next, another embodiment of the present invention will be described. In the above-described embodiment, the line element is input using the mouse or the like while watching the analysis target displayed on the display using the CAD device. However, the input method of arbitrary line elements is not limited to this. CAD
Instead of the device, a combination of a scanner and an image processing device can also be used.

When the scanner and the image processing apparatus are combined, a drawing of the analysis object to which line elements corresponding to the mesh data are added is prepared. Then, this drawing is read by a scanner, and the outline and the written line elements of the analysis object are extracted by the image processing apparatus. After that, the mesh data is generated by performing the processing from the intersection calculation processing on the extracted data in the same manner as in the above-described embodiment.

[0023]

As described above, according to the present invention, the input means for inputting an arbitrary line element corresponding to the drawing of the object to be analyzed and the intersection point calculating means for calculating the intersection points of the line elements to obtain the intersection point data. And a mesh data generation unit that calculates line segment data from adjacent intersections with respect to the line element and generates mesh data from the line segment data and the intersection point data. Since the minute data can be extracted to generate the mesh data, the operability is excellent, and it is possible to easily change the element density of the mesh as necessary.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a finite element method analysis system according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the system of FIG.

FIG. 3A is a diagram illustrating a line element input to a CAD device, and FIG. 3B is a diagram illustrating mesh data generated from the exemplified line element.

4A is a diagram showing an example of an analysis target object, and FIG. 4B is a diagram showing a state in which a line element is added to the analysis target object.

[Explanation of symbols]

 1 CAD device 2 Input data file 3 Intersection calculation part 4 Mesh generation part 5 Mesh output part 6 Mesh data file 7 Condition input part 8 Finite element method analysis calculation part 9 Analysis result file 10 Mesh data generation output part 21 Curve 22 Intersection point 23 element Boundary line 24 elements 101 to 104 steps

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location 7623-5L G06F 15/60 450 (72) Inventor Nobuto Nobu 46 Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture 59 Nippon Steel Plant Design Co., Ltd. (72) Inventor Miyazaki Shin-shi 59 Nippon Steel Plant Design Co., Ltd. 46 Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture (72) Inventor Shoichi Yamaguchi Sasebo City, Nagasaki Prefecture Nagiri Town No. 3-3 SEA Soken Co., Ltd.

Claims (3)

[Claims] 1. A data generation system for generating mesh data used for finite element method analysis, comprising: input means for inputting an arbitrary line element corresponding to a drawing of an object to be analyzed; Intersection calculation means for calculating intersections to obtain intersection data; and mesh data generation means for calculating line segment data from the intersections adjacent to the line element and generating mesh data from the line segment data and the intersection data. A data generation system for finite element method analysis, comprising: an output unit that outputs the mesh data. 2. The input means comprises: a display unit for displaying a drawing of an object to be analyzed; and an instruction input unit for inputting line elements on the drawing displayed on the display unit while sequentially displaying the line elements on the display unit. The data generation system for finite element method analysis according to claim 1, further comprising: 3. The data generation system for finite element method analysis according to claim 1, wherein the input means comprises image reading means for reading the drawing of the analysis object to which line elements are added and extracting the line elements.