JPH0844905A - Device and method for element conversion - Google Patents

Abstract

PURPOSE:To obtain an analytic result which is nearly as precise as that of an analytic model for elements of a hexahedron without increasing the calculation time by using an analytic model for tetrahedron elements. CONSTITUTION:The center coordinates and radii of the circumscribed spheres of respective tetrahedron elements of a finite element method are calculated (step S1) and the elements are selected and rearranged from elements which are near in circumscribed circle center coordinate and small in radius (steps S2 and S3); and the obtained elements are put together up to eight elements (steps S4 and S5) and converted into hexahedron elements (steps S6 and S7).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element conversion device and method for generating a hexahedral analysis model from a tetrahedral analysis model by numerical analysis such as structural strength analysis by the finite element method.

[0002]

2. Description of the Related Art In numerical analysis such as structural strength analysis by the finite element method, when an analysis model made of tetrahedral elements and an analysis model made of hexahedral elements are analyzed, the number of nodes is about the same. For example, an analysis model made of hexahedral elements can obtain a highly accurate analysis result. Therefore, it is necessary to increase the number of nodes in order to obtain an analysis result that is as accurate as an analysis model that is composed of tetrahedral elements and that is made of hexahedral elements. There is a problem that the calculation time is increased.

[0003]

As described above, an analytical model made of tetrahedral elements is inferior in accuracy to an analytical model made of hexahedral elements if the number of nodes is about the same. I had to increase the number of points and consequently the calculation time.

The present invention has been made in view of the above situation, and an object thereof is a numerical analysis by the finite element method, which is highly accurate without taking a calculation time from an analysis model of a tetrahedral element. An object of the present invention is to provide an element conversion device and method capable of obtaining an analysis result.

[0005]

That is, according to the present invention, the center coordinates and radius of the circumscribing sphere of each tetrahedral element of the finite element method are calculated, and the obtained center coordinates of the circumscribing sphere are close and the radius is small. The elements are sequentially selected and rearranged, and the elements are collectively converted into hexahedral elements until the number of nodes of the obtained elements becomes 8.

[0006]

With the above configuration, the analysis model of the hexahedral element can be obtained from the analysis model of the tetrahedral element, so that it is possible to obtain a highly accurate analysis result without increasing the calculation time. Becomes

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the apparatus according to the embodiment, where 11 is a tetrahedral element data storage unit that stores the tetrahedral element data to be analyzed, and 12 is stored in the tetrahedral element data storage unit 11. A program storage unit dedicatedly storing a conversion program for generating hexahedral element data from tetrahedral element data, 13 is a hexahedral element data storage unit for storing the hexahedral element data generated by the conversion program, and 14 is the program storage unit 12 The data processing for reading the tetrahedral element data stored in the tetrahedral element data storage unit 11 based on the conversion program stored in, generating hexahedral element data, and storing and storing the hexahedral element data in the hexahedral element data storage unit 13 is executed. Central processing unit, 15 is the central processing unit 14
A key input unit for inputting various commands relating to data processing in 16 and a display unit 16 for displaying and outputting a processing state and a processing result in the central processing unit 14.

FIG. 2 is a flow chart showing the data processing contents of the central processing unit 14 performed based on the conversion program stored in the program storage unit 12. At the beginning of the processing, the tetrahedral element data storage unit 11 stores the data. One piece of the generated tetrahedral element data is read out, the center coordinates and radius data of the circumscribing sphere are calculated and picked up (step S1).

FIG. 3 exemplifies this processing. T shown by a solid line in the drawing is tetrahedral element data which is currently focused on, CS is a circumscribed sphere CS of this tetrahedral element data T, and a dashed line. Shown is a set of other tetrahedral elements.

Next, from among the other tetrahedral element data stored in the tetrahedral element data storage section 11, one having a circumscribed sphere close to the center coordinates of the circumscribed sphere of the element of interest is selected (step S2). , The selected tetrahedral element data are rearranged in the ascending order of radius of the circumscribing sphere (step S3).

FIG. 4 shows six tetrahedral element data whose center coordinates of the circumscribing sphere including the tetrahedral element data T thus obtained are close to each other, and the circled numbers in the figure represent the radius of the circumscribing sphere. It represents a small order.

Next, the tetrahedral element data is added in the order in which the center coordinates of the circumscribed sphere are close and the radius of the circumscribed sphere is small, and the number of nodes is counted (step S4), and the count value becomes 8. It is determined whether or not (step S5
).

By repeating the above steps S1 to S5 until the count value of this node reaches exactly 8, hexahedral element data as shown in FIG. 5 can be obtained. In FIG. 5, black dots represent nodes.

The shape of the hexahedron element data thus obtained is subsequently checked (step S6),
Those that have passed are newly generated as hexahedral element data H as shown by the solid line in FIG. 6 and stored in the hexahedral element data storage unit 13 (step S7).

The above processing operations are sequentially executed while changing the tetrahedral element data of interest to make all the tetrahedral element data into a hexahedron, or all the remaining tetrahedral element models are used as the tetrahedral element data of interest. This processing operation is terminated when it is determined that the processing operation has been executed.

By executing the above processing,
For example, a set of tetrahedral element data as shown in FIG. 7A can be immediately converted into a set of hexahedral element data as shown in FIG. 7B.

The analysis model made of hexahedral elements can obtain a more accurate analysis result with the same number of nodes without increasing the calculation time as compared with the analysis model made of tetrahedral elements. Become.

[0018]

As described above, according to the present invention, an analysis model of hexahedral elements can be obtained from an analysis model of tetrahedral elements, so that a more accurate analysis result can be obtained without increasing the calculation time. It is possible to provide an element conversion device and method capable of performing the element conversion.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the processing contents according to the embodiment.

FIG. 3 is a diagram for explaining the operation according to the embodiment.

FIG. 4 is a view for explaining the operation according to the embodiment.

FIG. 5 is a view for explaining the operation according to the embodiment.

FIG. 6 is a view for explaining the operation according to the embodiment.

FIG. 7 is a view for explaining the operation according to the embodiment.

[Explanation of symbols]

11 ... Tetrahedral element data storage unit, 12 ... Program storage unit,
13 ... Hexahedral element data storage unit, 14 ... Central processing unit, 15 ...
Key input section, 16 ... Display section.

Claims (2)

[Claims] 1. A calculating means for calculating the center coordinates and radius of the circumscribing sphere of each tetrahedral element of the finite element method, and the center coordinates of the circumscribing sphere obtained by the calculating means are close to each other, and those having the smallest radius are in order. And an element selecting unit for selecting and rearranging the elements, and a converting unit for collectively converting the elements into hexahedral elements until the number of nodes of the element obtained by the element selecting unit becomes 8. Element conversion device. 2. A calculation process for calculating the center coordinates and radius of a circumscribing sphere of each tetrahedral element of the finite element method, and the center coordinates of the circumscribing sphere obtained in this calculating process are close to each other, and the radius is small in order. The present invention is characterized by having an element selection process for selecting and rearranging elements and a conversion process for collectively converting the elements into hexahedral elements until the number of nodes of the element obtained by this element selection process becomes eight. Element conversion method.