JP2003167927A - Element dividing device, element dividing method, element dividing program and computer readable recording medium with element dividing program recorded thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the analytical accuracy, and to shorten the analytical time. <P>SOLUTION: This element dividing device prepares analytical element data used for a structural analysis using a finite element method, and has an object shape input means (S01) for inputting a shape model being an object of the structural analysis, an analytical model making means (S05) for making an analytical model by simplifying a shape element deteriorating in an element quality among shape elements for constituting the inputted shape model, and an automatic element dividing means (S08) for making analytical element data by using the analytical model. Since the shape element deteriorating in the element quality is simplified, a quality of the analytical element data is improved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element dividing device,
The present invention relates to an element dividing method, an element dividing program, and a computer-readable recording medium recording the element dividing program, and in particular, an element dividing device and element dividing method for creating analysis element data used for structural analysis by the finite element method.
The present invention relates to an element division program and a computer-readable recording medium recording the element division program.

[0002]

2. Description of the Related Art In recent years, numerical analysis represented by finite element analysis has been widely used as a computer aided design (CAD) tool for solving engineering problems represented by partial differential equations. In this analysis, a finite element division model in which an object is divided into finite elements is used. JP-A-10-91
Japanese Laid-Open Patent Publication No. 813 describes an automatic element division method for performing various analyzes of an analysis target. This automatic element division method has a small finite element in a region that is important for analysis (for example, a region in which stress changes rapidly) and a finite element in a region that is not important for analysis (for example, a region in which stress changes gradually). The elements are finite element sparse to dense. For this reason, the elements are once roughly divided, the density of the stress is obtained as a result of the analysis, the elements are coarsely and densely divided, and the elements are again divided, and the calculation is performed again. By using this automatic element division method, both improvement of analysis accuracy and reduction of calculation cost can be achieved. This method is called adaptive mesh analysis.

[0003]

However, the technique disclosed in Japanese Unexamined Patent Publication No. 10-91813 cannot be roughly divided into elements in the case of a geometric element having a minute area. There was a problem that element division had to be performed densely in the vicinity of a shape having a minute region regardless of sex.

In the setting of the coarse density function, if the automatically set element size is larger than the shape element due to the element division by the coarse density function automatically performed, the element shape becomes distorted. Therefore, there is a problem that a calculation error increases due to an increase in the ratio of the maximum side and the minimum side in a single element. Furthermore, since the number of elements increases in the vicinity of a shape having a minute area, there is a problem that the storage area of the computer is exhausted and calculation cannot be performed, or the calculation cannot be completed within an effective time.

The present invention has been made to solve the above-mentioned problems, and it is possible to improve analysis accuracy and shorten analysis time, an element dividing device, an element dividing method, an element dividing program, and an element dividing method. It is to provide a computer-readable recording medium in which a program is recorded.

[0006]

According to one aspect of the present invention for achieving the above-mentioned object, an element dividing device is an element dividing device for generating element data for analysis used for structural analysis using the finite element method. A device for inputting a shape model to be subjected to structural analysis, and an analysis model by simplifying the shape element of which the element quality deteriorates among the shape elements forming the input shape model. And an automatic element dividing means for creating analysis element data using the analysis model.

According to the present invention, among the shape elements forming the input shape model, the shape elements whose element quality is deteriorated are simplified. Therefore, the quality of the analysis element data is improved. As a result, it is possible to provide an element dividing device capable of improving analysis accuracy and shortening analysis time.

Preferably, the analysis model creating means simplifies the shape element when the shape element selecting means for selecting a characteristic shape element from the shape model and the selected shape element is smaller than a predetermined size. And simplification means.

According to the present invention, when the characteristic shape element selected from the shape model is smaller than a predetermined size, the shape element is simplified. Since the shape elements smaller than the predetermined size are simplified, unnecessary analysis element data and analysis element data having a crushed shape are not created.

Preferably, the apparatus further comprises size designating means for inputting a predetermined size, and display means for displaying the analysis model in response to the size input by the size designating means.

According to the present invention, since the analysis model is displayed when the size is input, it is possible to change the size while visually recognizing the desired analysis model.

According to another aspect of the present invention, an element division method is an element division method for creating analysis element data used for structural analysis using the finite element method, and a shape to be subjected to structural analysis. The step of inputting a model, the step of creating a model for analysis by simplifying the shape elements of which the element quality deteriorates among the shape elements constituting the input shape model, and the element data for analysis using the model for analysis And a step of creating.

According to the present invention, among the shape elements forming the input shape model, the shape elements having deteriorated element quality are simplified. Therefore, the quality of the analysis element data is improved. As a result, it is possible to provide an element division method capable of improving analysis accuracy and reducing analysis time.

According to still another aspect of the present invention, the element division program is an element division program that causes a computer to create analysis element data used for structural analysis using the finite element method, and is a target of structural analysis. The step of accepting the input of the shape model, the step of creating the analysis model by simplifying the shape element whose element quality deteriorates among the shape elements forming the input shape model, and the analysis model are used. Causing the computer to execute the steps of creating the element data for analysis.

According to the present invention, it is possible to provide an element division program capable of improving the analysis accuracy and shortening the analysis time, and a computer-readable recording medium recording the element division program.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding members, and the duplicated description will not be repeated.

FIG. 1 is a diagram showing a schematic configuration of an element dividing device in one of the embodiments of the present invention. The element dividing device 100 is configured by a computer or the like. Referring to FIG. 1, the element dividing device 100 includes a control unit 101 for controlling the entire element dividing device 100, a display unit 102,
The input unit 104 and the storage unit 103 are included.

The control unit 101 is a central processing unit (CPU)
A read-only memory (ROM) for storing a program executed by the CPU, and a random access memory (RAM) used as a work area for storing variables and the like when the program is executed by the CPU.

The input unit 104 is a keyboard, a mouse or the like. The display unit 102 is a liquid crystal display device or a cathode ray tube (CRT). The display unit 102 displays predetermined information based on an instruction from the control unit 101. Storage unit 10
Reference numeral 3 is a storage device such as a magnetic disk or a magneto-optical disk.

The element dividing device 100 includes an external storage device 10.
Connected with 5. The external storage device 105 is the recording medium 10
The control unit 1 reads the program and data recorded in 6
Send to 01. In the control unit 101, the external storage device 10
It is possible to execute the program read in 5. When the element division program is recorded in the recording medium 106, the element division program recorded in the recording medium 106 is read by the external storage device 105, and the control unit 10
It will be executed in 1.

The recording medium 106 is a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (R) disk or a hard disk, and a CD-ROM / M.
Optical discs such as O / MD / DVD, card systems such as IC cards (including memory cards) and optical cards, or mask ROM, EPROM, EEPROM, flash R
It may be a medium that fixedly carries the program, including a semiconductor memory such as an OM. Also, the element dividing device 1
00 may be connected to a communication network including the Internet, and may be a medium that carries the program in a fluid manner such that the program is downloaded from the communication network.

FIG. 2 is a block diagram showing an outline of functions of the element dividing device 100 in this embodiment. With reference to FIG. 2, the element dividing device 100 includes an object shape input unit 113 for inputting the shape of the object, and an analysis model creation for creating an analysis model from the input object shape. A section 110, a minute area function setting section 115 for setting a minute area function that is a threshold value for creating an analysis model, and element data for analysis by performing element division using the created analysis model. And an automatic element dividing unit 117 for creating

The analysis model creating section 110 includes a shape element automatic selecting section 111 for automatically selecting a characteristic shape element based on the input shape of the object, and a selected shape element and a minute shape element. A shape element simplifying unit 112 for comparing the minute area function set by the area function setting unit 115 and simplifying the shape element determined to be the minute area is included.

The minute area function setting unit 115 sets the size for determining the shape element as a minute area. The size for determining a minute area is represented by a minute area function.
The micro area function is represented as a coefficient between 0 and 0.5, for example.

The object shape input unit 113 inputs the shape of the object. The object means an object of structural analysis. The shape of the object is input using an input device such as a keyboard of the input unit 104 or a mouse. In addition, separately CAD
The configuration may be such that the shape data created using software is input as it is.

The shape element automatic selection unit 111 divides the shape of the object into shape elements, and compares and extracts the divided shape elements with a characteristic basic shape. Many methods are known for dividing the shape of an object into shape elements, but here, the following method is used for division. The dividing method is not limited to the following method, and other methods can be used as long as the object shape can be divided into shape elements using the basic shape.

First, there is a method of preparing a plurality of basic shapes and subtracting the basic shape from the shape of the object. The subtracted basic shape constitutes the shape element. The conditions for division are
The shape element has a shape that includes the basic shape in the maximum size, and that the number of shape elements after division is the minimum.

The basic shape means a basic shape such as a rectangular parallelepiped, a cylinder, a triangular pyramid, and a sphere, and is stored in the storage unit 103 in advance. Therefore, the shape of the shape element corresponds to any of these basic shapes.

The shape element automatic selection unit 111 compares the shape element obtained by the division with the characteristic basic shape, and extracts the shape element of the same type as the characteristic basic shape. The extracted shape element is attached with an identification number and stored in the RAM of the control unit 101. Here, the identification number is a continuous integer added in the order of extraction.

The characteristic basic shape is a basic shape that influences the element division performed by the automatic element division unit 117 described later.

It should be noted that the shape element obtained by the division is compared with the characteristic basic shape, and instead of extracting the shape element of the same type as the characteristic basic shape, the shape element having a predetermined attribute is extracted. You may

The small area function setting unit 115 sets the size for selecting the shape element to be simplified by the shape element simplifying unit 112.

The shape element simplifying unit 112 recognizes a shape element, which is smaller than the size set by the small area function setting unit 115, among the shape elements selected by the automatic shape element selecting unit 111 as a small area, and Simplify the elements. A model for analysis is created by simplification. The created analysis model is transmitted to the automatic element dividing unit 117.

The simplification is, for example, a process of deleting a shape element having a first attribute such as a step or a protrusion, or a process of filling a shape element having a second attribute indicating a space such as a hole or a crack.

The automatic element division unit 117 divides the analysis model received from the shape element simplification unit 112 into elements to generate analysis element division data. The analysis element division data is stored in the storage unit 103.

Next, a specific example of the minute area function setting section 115 will be described. FIG. 3 is a diagram showing one specific example of the minute area function setting unit. With reference to FIG. 3, the minute area function setting unit 115 includes a display 102 of the display unit 102.
A and a mouse 104A of the input unit 104.
The display area 140 and the slide bar 120 are displayed on the display 102A. The mouse 104A is a pointing device and can specify an arbitrary position on the display 102A with a pointer. When the operator uses the mouse 104A to move the mark 121 to the "small" position at the left end of the slide bar 120, "0" is set in the minute area function. On the contrary, the mark 121
When is moved to the “large” position at the right end of the slide bar 120, “0.5” is set to the minute area function. Mark 1
When 21 is at an intermediate position other than the right end or the left end of the slide bar 120, the position of the mark 121 in the slide bar 120 and the minute area function linearly correspond to each other and "minute area function = position information". Become. Instead of linear correspondence, “small area function = positional information × positional information” may be used, and the small area function may be curvedly changed according to the change in the positional information.

In this way, the minute area function set by the minute area function setting section defines the size for determining the shape element to be simplified by the shape element simplifying section 112.

Next, an example of the division processing of the object shape will be shown. FIG. 4 is a diagram illustrating an example of the shape of the target object input by the target object shape input unit 113. FIG. 5 is a diagram for explaining the process of dividing the object shape 130 shown in FIG. In the division processing here, the shape elements of the same type as the basic shape such as a rectangular parallelepiped, a cylinder, a triangular pyramid, and a sphere stored in advance in the storage unit 103 are divided. The division of the shape element is performed on condition that the shape of the shape element to be divided is a shape including the basic shape with the maximum size and the number of shape elements after the division is the minimum. Further, even in the shape after subtracting the basic shape from the object shape, it is kept remembered that the shape before the subtraction existed, and is used as a dividing line for the next subtraction.

Referring to FIGS. 4 and 5, the object shape 1
From 30, the rectangular parallelepiped shape element 1 which is the same as the basic shape of the rectangular parallelepiped
31 is divided (FIG. 5 (A)). Next, the rectangular parallelepiped shape element 132 is divided (FIG. 5B). Further, the rectangular parallelepiped shape element 133 is divided (FIG. 5C). In this way, the shape elements are divided in order, and finally, as shown in FIG.
As shown in (D), it is divided into seven shape elements 131 to 137.

The shape element 137 is a recess and the attribute is a hole. The shape element 136 includes the shape element 135 and the shape element 1.
It is located between 37 and 37, and the amount of protrusion is small, so it is determined to be a step, and the attribute is a rectangular parallelepiped. The attributes of the other shape elements 131 to 135 are rectangular parallelepipeds.

FIG. 6 is a flowchart showing the flow of element division processing executed by the element division device 100 according to this embodiment. Referring to FIG. 6, in the element division processing,
First, the shape of the object is input from the object shape input unit 113 (step S01). Input may be made from an input device such as a keyboard of the input unit 104, or C
The shape data created using the AD software may be directly input.

In the next step S02, the input object shape is divided into shape elements. The divided shape elements are stored in the storage unit 103.

Next, a shape element of the same type as the characteristic basic shape stored in advance in the storage unit 103 is automatically selected from the shape elements stored in the storage unit 103 (step S03).

Then, the minute area function setting unit 115 sets the minute area function (step S0).
4). In the next step S05, the shape element selected in step S03 is compared with the small area function set in step S04, and processing for simplifying the small area shape element is performed. The simplification process is performed, for example, by deleting the shape element having the first attribute such as a protrusion or a step and filling the shape element having the second attribute indicating a space such as a hole or a crack. When the shape element simplification process is performed on the object shape, an analysis model is created.

In step S06, the created analysis model is displayed in the area 1 of the display 102A of the display unit 102.
40 is displayed. As a result, each time the mark 121 of the slide bar 120 is moved to an arbitrary position, the area 14
At 0, the analysis model in which the simplification process of the shape element is performed is displayed. Therefore, the operator can set the minute area function while looking at the analysis model.

In the next step S07, the operator looks at the analysis model and determines whether the minute area function is set to a desired value. This determination is made by the operator pressing, for example, the enter key of the keyboard.

In step S07, if a signal indicating OK, which is input by pressing the enter key, is input, the process proceeds to step S08, and if not, the process returns to step S04.

In step S08, the automatic element dividing unit 117 performs element division processing on the analysis model. When the element division process is performed, analysis element data is generated from the analysis model and stored in the storage unit 103 (step S09).

FIG. 7 is a diagram showing an example of characteristic shape elements used in the element dividing device 100 according to the present embodiment. FIG. 7A shows a first shape element example, and FIG.
(B) shows a second shape element example. With reference to FIG. 7A, a rectangular parallelepiped 150 is shown in the first shape element example. Referring to FIG. 7B, a cylinder 151 is shown as a second shape element example. The characteristic shape element is
The shape is not limited to these as long as it has an effect on element division.

FIG. 8 is a flow chart showing the flow of shape element selection processing executed in step S03 of FIG. Referring to FIG. 8, in the shape element selection process, first,
"0" is substituted for the variable i (step S11). The variable i is a variable for specifying the shape element generated by dividing the object by the shape dividing process. By the dividing process of the object, the shape of the object is divided into a plurality of shape elements, each of which is provided with an identification number, and the storage unit 103
Was remembered in. The variable i is a variable for specifying this identification number.

In the next step S12, it is determined whether or not the variable i exceeds the number of shape elements of the analysis object. The number of shape elements of the analysis target refers to the number of shape elements stored in the storage unit 103. That is, it is determined whether or not the following steps have been executed for all the shape elements stored in the storage unit 103. If it is determined that the variable i exceeds the number of shape elements of the analysis object, the process ends, otherwise, the process proceeds to step S13.

In step S13, it is determined whether or not the shape element with the identification number i of the shape element is of the same type as the first shape element example. If it is determined that the shapes are the same, the process proceeds to step S15, and if not, the process proceeds to step S14.

The first shape element example was a rectangular parallelepiped 150. Therefore, it is determined whether the i-th shape element is a rectangular parallelepiped. If it is determined to be a rectangular parallelepiped, step S15
Otherwise, to step S14.

In the next step S14, it is determined whether or not the shape element with the identification number i is the same kind of shape as the second shape element example. If it is determined that the shapes are the same, the process proceeds to step S15, and if not, step S15.
Proceed to 16. The second example shape element was a cylinder 151. Therefore, if the shape element with the identification number i is a cylinder, the process proceeds to step S15, and if not, the process proceeds to step S16.

In step S15, the shape element having the identification number i is stored in the storage unit 103. When stored in step S14, a new identification number is assigned to the selected shape element in the order of registration.

In step S16, "1" is added to the variable i. Then, the process proceeds to step S12.

In the shape element selection processing, for all the shape elements obtained by dividing the shape of the object, the characteristic shape elements stored in the storage unit 103, here, the first shape element example And it is determined whether or not the shape is the same type as the second shape element example. A shape element of the same type as the characteristic shape element is newly registered in the storage unit 103.

As compared with the shape of the object shown in FIG.
When the shape element of the object shown in FIG. 3 is divided, all the shape elements 131 to 137 are rectangular parallelepipeds, and therefore have the same type of shape as the rectangular parallelepiped 150 of the first shape element example. Therefore, all the shape elements 131 to 137 are selected and stored in the storage unit 103.

FIG. 9 is a flow chart showing the flow of the shape element simplification process executed in step S05 of FIG. Referring to FIG. 9, first, "0" is substituted for variable i (step S21). The variable i is a variable for specifying the shape element stored in the storage unit 103 in the shape element selection process. In the process of selecting the shape elements, characteristic shape elements, that is, shape elements having the same shape as the first shape element example and the second shape element example are numbered and stored in the storage unit 103. The variable i indicates the number given to this shape element.

In the next step S22, it is determined whether or not the variable i exceeds the total number of shape elements registered in the storage unit 103. This processing is to execute the subsequent processing for all the shape elements selected in the shape element selection processing. If it is determined that the variable i exceeds the total number of shape elements, the process ends, otherwise, step S2.
Go to 3.

In step S23, the shape element corresponding to the variable i registered in the storage unit 103 is called from the storage unit 103. Then, in the next step S24, it is determined whether or not the size of the called shape element is larger than the size set in the small area function. If it is determined to be small, the process proceeds to step S25, and if not, the process proceeds to step S26.

In step S24, the object shape input unit 1
The threshold value is calculated based on the maximum height, the maximum width, the maximum depth, and the value set for the minute area function of the object shape input in 13. This threshold value is calculated by the following equation.

Threshold value = (maximum height + maximum width + maximum depth) / 3 × value of minute area function (1) For example, the maximum height of the object shape is 10 mm, the maximum width is 40 mm, and the maximum depth is If the value set for the minute area function is 0.1 mm, the threshold value is (1)
From the formula, (10 + 40 + 30) ÷ 3 × 0.1≈2.7
(Mm).

Then, in step S24, if the plate thickness or diameter that is the characteristic dimension of the i-th shape element is smaller than 2.7 mm, the process proceeds to step S25, and if not, the process proceeds to step S26.

In step S25, the i-th shape element is simplified. To simplify the shape element, when the shape element has a projection attribute, the shape element is deleted. If the attribute of the shape element is the attribute of hole, the space is filled.

In step S26, "1" is added to the variable i, and the process proceeds to step S22. When the shape of the object shown in FIG. 4 is divided into the shape elements shown in FIG. 5, all the shape elements 131 to 137 are selected in the shape element selection processing and stored in the storage unit 131. . In the simplification process of the shape element, for all the shape elements 131 to 137 stored in the storage unit 103, the plate thickness, width, or height that is the characteristic dimension of each shape element is
It is determined whether or not it is smaller than 2.7 mm, and if it is smaller, simplification processing is performed. Here, if the shape element 136 has a plate thickness smaller than 2.7 mm, the shape element 136 is deleted because the attribute of the shape element 136 is a protrusion.

Then, the object shape 13 to be analyzed
The shape in which the shape element 136 is deleted from 0 is stored in the storage unit 103 as an analysis model.

In step S26, "1" is added to the variable i, and the process returns to step S22. FIG. 10 is a diagram showing an example in which the analysis model in which the shape elements have been simplified is divided into elements. With reference to FIG. 10, by deleting the shape element 136 having a minute shape which is a step, it is divided into elements having a shape close to a regular hexahedron. The elements divided by the element division are divided so as to approach a square, a regular triangle, a regular hexahedron, or a regular tetrahedron.

Referring to FIG. 10, since the divided elements are divided in a shape close to a square, an increase in calculation error due to an increase in the ratio of the maximum side to the minimum side in a single element is prevented. Can be prevented. Further, since the number of elements does not increase in the vicinity of a shape having a minute area, it is possible to perform structural analysis within an effective time without exhausting the storage area of the computer.

FIG. 11 is a diagram showing an example in which the shape of the object is divided into elements without performing the simplification processing of the shape elements. With reference to FIG. 11, since the shape element 136 is not deleted, the shape element 136, which is a step, is divided into small elements in order to divide a minute step.
For this reason, it is divided into unnecessarily small elements or elements whose shapes are crushed, which lowers the analysis accuracy and increases the calculation time.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an element dividing device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of functions of an element dividing device according to the present embodiment.

FIG. 3 is a diagram showing one specific example of a minute area function setting unit.

FIG. 4 is a diagram showing an example of the shape of an object input by an object shape input unit.

FIG. 5 is a diagram for explaining a process of dividing the target object shape shown in FIG.

FIG. 6 is a flowchart showing the flow of element division processing executed by the element division device according to the present embodiment.

FIG. 7 is a diagram showing an example of characteristic shape elements used in the element dividing device according to the present embodiment.

FIG. 8 is a flowchart showing a flow of a shape element selection process executed in step S03 of FIG.

FIG. 9 is a flowchart showing a flow of shape element simplification processing executed in step S05 of FIG. 6;

FIG. 10 is a diagram showing an example in which an analysis model in which a shape element is simplified is divided into elements.

FIG. 11 is a diagram showing an example in which the shape of an object is divided into elements without performing the simplification process of the shape elements.

[Explanation of symbols]

100 element dividing device, 101 control unit, 102 display unit, 102A display, 103 storage unit, 104
A mouse, 104 input unit, 105 external storage device,
106 recording medium, 110 analysis model creating section, 11
1 shape element automatic selection unit, 112 shape element simplification unit,
113 object shape input unit, 115 small area function setting unit, 117 automatic element dividing unit, 120 slide bar,
121 mark.

Claims (6)

[Claims] 1. An element dividing device for creating element data for analysis used in structural analysis using the finite element method, comprising object shape input means for inputting a shape model to be subjected to structural analysis. Of the shape elements that make up the shape model,
An element dividing device including an analysis model creating unit that creates an analysis model by simplifying a shape element whose element quality deteriorates, and an automatic element dividing unit that creates analysis element data using the analysis model. . 2. The analysis model creating means selects a shape element that is a characteristic shape element from the shape model, and selects the shape element when the selected shape element is smaller than a predetermined size. The element dividing device according to claim 1, further comprising a simplification means for simplifying. 3. The apparatus according to claim 1, further comprising size specifying means for inputting the predetermined size, and display means for displaying the analysis model in response to the size input by the size specifying means. The described element dividing device. 4. An element division method for creating element data for analysis used in structural analysis using the finite element method, comprising the step of inputting a geometric model to be subjected to structural analysis, and the inputted geometric model. Of the shape elements that make up
An element division method, comprising: a step of creating a model for analysis by simplifying a shape element whose element quality deteriorates; and a step of creating element data for analysis using the model for analysis. 5. An element division program for causing a computer to create element data for analysis used in structural analysis using the finite element method, the step of receiving an input of a shape model to be subjected to structural analysis, Of the shape elements that make up the shape model,
An element dividing program that causes a computer to execute a step of creating a model for analysis by simplifying a geometrical element whose element quality deteriorates and a step of creating element data for analysis using the model for analysis. 6. A computer-readable recording medium in which the element division program according to claim 5 is recorded.