JP5151601B2 - Stress analysis apparatus and method - Google Patents

Description

  The present invention relates to a stress analysis apparatus and method, and more particularly to a stress analysis apparatus and method using a finite element method, and belongs to the technical field of data processing.

  In general, for example, when developing a new vehicle in the automobile industry, the stress generated due to various external forces input to the vehicle body under the driving environment is analyzed for the vehicle body of the developed vehicle, and based on the analysis results. The development vehicle design changes and improvements are made. In that case, a finite element method (FEM) is well known and widely used as one of stress analysis methods. In stress analysis using this finite element method, the analysis target area is divided into a finite number of elements defined by connecting the nodes, and the stress is calculated by setting the load conditions, material characteristics, etc. for each divided element. Is.

  For example, in Patent Document 1, as a technique for improving the accuracy of stress analysis using a finite element method, first, the entire model and the local model cut out from the entire model are roughly divided and the first stress analysis is performed. Describes that when the model is divided into two parts and the second stress analysis is performed, the displacement of the node on the cut line obtained from the first analysis result is input and the second local model stress analysis is performed. Has been.

JP-A-7-55656 (paragraph 0009)

  By the way, for example, in order to find a place where there is a possibility of fracture or the like due to stress concentration in the analysis target area, the developer in charge analyzes the area to be analyzed into a plurality of sections (spaces where the analysis target area exists are regularly arranged). Divided into multiple areas and areas occupied by multiple parts constituting the analysis target area, etc.), what is the maximum stress generated in each area, and the maximum stress is generated You may consider where the site is. In this case, when the number of elements included in one area is relatively small, the analysis result (stress distribution indicating the stress calculated for each element) is displayed on the screen and output, or Whether printed on paper or output, the problem is still small.

  However, in the case of the entire vehicle body in which the analysis target area is a relatively large object, such as the development of a new car in the automobile industry, for example, the range itself of one area in which the analysis target area is divided into a plurality of areas is greatly increased. . In general, in order to improve the analysis accuracy, when the analysis target area is divided finely, the total number of elements increases. Therefore, these factors tend to increase the number of elements included in one area. Then, the developer looks at the analysis results (stress distribution showing the stress calculated for each element) on the screen or on the printed material, Finding the maximum stress and finding the maximum stress generation site in each area is a very time-consuming and complicated operation.

  The present invention addresses the above-described problem in stress analysis using the finite element method, even if the analysis target area is relatively large, and even if the number of elements is relatively large in order to improve analysis accuracy, Make it possible for developers to easily grasp the maximum stress in each area divided into multiple analysis target areas, in other words, to easily find the maximum stress value from the analysis results. Is an issue.

  In order to solve the above problems, the present invention uses the following means.

First, the invention according to claim 1 of the present application is an apparatus for analyzing stress using a finite element method, and calculates a stress for each element by dividing an analysis target region into a finite number of elements. Classification means for dividing the analysis target region into a plurality of areas each consisting of a set of a plurality of elements, recording means for recording the areas divided by the sorting means and elements included in the areas in association with each other, and the recording means Selecting means for selecting the element having the maximum stress calculated by the calculating means for each area recorded in (1), and outputting the stress of the element selected by the selecting means as a value of the area including the element have a means, said output means, and outputs together the position of selected by the selection means element.

  Here, specific examples of the “zone” in claim 1 include a regular division of a space where the analysis target region exists, a region occupied by a plurality of parts constituting the analysis target region, and the like. Can be mentioned.

Next, in the invention according to claim 2 of the present application, in the stress analysis apparatus according to claim 1 , the output unit displays the stress and position of the element selected by the selection unit on the screen. The stress and the position are output.

Next, the invention according to claim 3 of the present application is the stress analysis apparatus according to claim 2 , wherein the output means displays a stress distribution in which each element is color-coded based on the stress calculated by the calculating means. The stress and the position are displayed on a screen while being displayed on the screen.

Next, the invention according to claim 4 of the present application is the stress analysis apparatus according to claim 2 or 3 , wherein the calculation means divides a plurality of different analysis target regions into a finite number of elements, respectively. Then, the stress is calculated for each element, the sorting means divides each analysis target area into a plurality of sections each consisting of a set of a plurality of elements, and the recording means sets each analysis target area for each analysis target area. The areas classified by the classification means and the elements included in the areas are recorded in association with each other, and the selection means calculates the calculation for each area recorded by the recording means for each analysis target area. The element having the maximum stress calculated by the means is selected, and the output means displays the stress and the position of the element selected by the selection means on the screen in a similar area between the analysis target areas. The And butterflies.

Next, the invention according to claim 5 of the present application is the stress analysis apparatus according to any one of claims 1 to 4 , wherein the selection means is a method of spot welding by overlapping three plates. An element having the maximum stress is selected by excluding elements belonging to the intermediate plate.

Next, an invention according to claim 6 of the present application is a method of analyzing stress using a finite element method in a computer system, wherein the computer system divides an analysis target region into finite elements and then analyzes each region. A calculation step for calculating stress for each element, a division step for dividing the analysis target area into a plurality of areas composed of a set of a plurality of elements, and the areas divided in this division step are associated with the elements included in the areas A recording step for recording, a selection step for selecting an element having the maximum stress calculated in the calculation step for each area recorded in the recording step, and a stress of the element selected in the selection step in an area including the element An output step of outputting as a value is executed, and in the output step, the position of the element selected in the selection step is also output .

Here, specific examples of the “section” in claim 6 include a regular division of a space where the analysis target region exists, a region occupied by a plurality of parts constituting the analysis target region, and the like. Can be mentioned.

First, according to the first and sixth aspects of the invention, the analysis target region is divided into a finite number of elements, and stress analysis for calculating stress for each divided element, that is, stress analysis using a finite element method. , The analysis target area is divided into a plurality of areas composed of a set of a plurality of elements, the divided areas and the elements included in the areas are recorded in association with each other, and the element having the maximum stress in each recorded area Is selected, and the stress of the selected element is output as the value (representative value) of the area in which the element is included. By looking at the analysis result (stress distribution showing the stress calculated for each element), finding the maximum stress in each area that divided the analysis target area into multiple areas from a lot of data. Without the time-consuming and cumbersome work The need be. Instead, the developer is output even if the analysis target area is relatively large, or even if the number of elements is relatively large to improve analysis accuracy, for example, on the screen or on printed matter. It is possible to easily grasp the maximum stress in each area by looking at the measured value (representative value), in other words, to easily find the value of the maximum stress from the analysis result.

In this case, according to the present invention , since the position of the selected element is also output, not only the maximum stress but also the positional information indicating which element the maximum stress is calculated is. For example, the developer in charge sees the output representative value and the element position on the screen or printed material, for example, the maximum stress in each area, and the part where the maximum stress occurs At the same time, in other words, it is possible to easily find the value of the maximum stress and the location where the stress occurs from the analysis result at the same time.

Next, according to the second aspect of the present invention, since the stress and the position of the selected element are displayed on the screen, the stress and the position are output. For example, it is possible to recognize the maximum stress and position information in each area by looking at the displayed maximum stress and position information on the screen instead of on the printed matter.

Next, according to the invention described in claim 3 , the stress distribution of the selected element and the position of the element are displayed on the screen while the stress distribution in which each element is color-coded based on the calculated stress is displayed on the screen. As a result, the person in charge of development can see the color distribution of the stress distribution on the screen and grasp the entire stress distribution in each area at a glance by the color difference.

Next, according to the fourth aspect of the present invention, the stress of the selected element and the position of the element are displayed on the screen side by side in a similar area between a plurality of different analysis target areas. , Developers look at the maximum stress and position information displayed on one screen, and compare and compare the analysis results of similar areas of different items, for example, the evaluation standard product and the developed product This can be easily done and greatly contributes to design changes and improvements based on the analysis results.

Next, according to the fifth aspect of the present invention, the element having the maximum stress is selected by excluding the element belonging to the middle plate of the portion where the three plates are overlapped and spot-welded. For elements belonging to the middle plate of the spot-welded part that overlaps the plates, even if the maximum stress occurs in the area, it will not be taken into consideration for design changes or improvements based on the analysis results.

  The reason why this is done is that the middle plate of the spot welded by overlapping the three plates is sandwiched between the upper and lower plates, even if stress concentration occurs and breaks at the welded part, etc. This is because there are relatively few problems. Rather, it is more important to know whether the maximum stress is generated on the upper and lower plates that are scattered and break down when there is a problem in terms of appearance and physical properties. Select the element that generates the maximum stress. In this case, by removing elements belonging to the middle plate, when the maximum stress is generated in the upper and lower plates, the information is surely transmitted to the developer.

  In addition, by excluding unnecessary elements in this way, the number of data when selecting an element that generates the maximum stress is reduced, and there is an advantage that the selection is facilitated. Hereinafter, the present invention will be described in more detail through the best mode for carrying out the invention.

  FIG. 1 is an overall configuration diagram of a stress analysis apparatus 1 according to the present embodiment. The stress analysis apparatus 1 is configured by a computer system, and includes a control unit 10 such as a CPU, a recording unit 20 such as a memory, an input unit 30 such as a keyboard and a mouse, and an output unit 40 such as a display and a printer. Connected by bus. The operation performed by the stress analysis apparatus 1 constitutes the stress analysis method of the present invention.

  As shown in FIG. 2, the recording unit 20 includes a stress analysis program 21 for executing stress analysis using a finite element method, a drawing program 22 for creating an image representing the result of stress analysis, and a CAD database. 23, an area database 24, an element database 25, a stress database 26, an area element correspondence table 27, and a maximum stress selection table 28 are stored.

  First, as shown in FIG. 3, the CAD database 23 has a structure in which an analysis target area and a 3D image are recorded using a CAD number as a key. According to the illustrated example, a 3D image of “evaluation reference car No. 1” is recorded in the CAD number “cad0001”, and a 3D image of “development car No. 1” is recorded in the CAD number “cad0101”. It is recorded.

  Here, the “evaluation reference vehicle” is a vehicle (for example, an existing vehicle) that is a reference for evaluation in stress analysis, and the “development vehicle” is a development stage in which the evaluation result is compared with the evaluation reference vehicle. Vehicle.

  Next, as shown in FIG. 4, the area database 24 has a structure in which the X-axis range (mm), the Y-axis range (mm), and the Z-axis range (mm) are recorded using the area number as a key. It has become. According to the example in the figure, the zone number “K0001” is recorded with “0000 mm” to “0225 mm” as the X-axis range, “0000 mm” to “0200 mm” as the Y-axis range, and Z-axis. The range from “0000 mm” to “0100 mm” is recorded, and the area number “K1768” is recorded from “1575 mm” to “1800 mm” as the X-axis range, and from “3200 mm” to “3400 mm as the Y-axis range. ”And“ 1200 mm ”to“ 1300 mm ”are recorded as the Z-axis range.

  Here, with reference to FIG. 5, the relationship between the three-dimensional CAD image of the vehicle body α, which is the analysis target region, and the area will be described. In FIG. 5, the symbol α indicates the body of the automobile that is the analysis target area of the present embodiment. The 3D CAD image of the vehicle body α is recorded in the 3D image of the CAD database 23 of FIG. In the illustrated example, the vehicle body α has a vehicle width along the X axis slightly smaller than 1800 mm, a vehicle length along the Y axis slightly smaller than 3400 mm, and a vehicle height along the Z axis slightly smaller than 1300 mm. is there. 4 is a section (hereinafter referred to as “K”) that is regularly divided into a plurality of spaces in which the vehicle body α, which is the analysis target area, exists.

  More specifically, in the present embodiment, the space in which the vehicle body α is present is divided into 8 equal parts on the X axis, 17 equal parts on the Y axis, and 13 equal parts on the Z axis. As a result, the size of one area K is 225 mm (= 1800 mm / 8) in the X-axis dimension, 200 mm (= 3400 mm / 17) in the Y-axis dimension, and 100 mm (= 1300 mm / 13) in the Z-axis dimension. In addition, the total number of sections K is 1768 (= 8 × 17 × 13). 4 is assigned in the ascending order in the ascending order of the X axis, the Y axis, and the Z axis. Therefore, the area K in the lower right front corner of the vehicle body α is the first first area “K0001”, and the area K in the upper left rear corner of the vehicle body α is the last 1768th area “K1768”.

  In short, the area database 24 shown in FIG. 4 records the range of the area K for each area K obtained by dividing the vehicle body α, which is the analysis target area, into a plurality of areas K.

  Next, as shown in FIG. 6, the element database 25 uses the element number as a key, and the X-axis coordinate (mm), the Y-axis coordinate (mm), the Z-axis coordinate (mm), and the belonging part number. It has a recorded structure. According to the example in the figure, the element number “E000001” is recorded with “0003 mm” as the X-axis coordinate, “0003 mm” as the Y-axis coordinate, and “0003 mm” as the Z-axis coordinate. “PID *******” is recorded as the part number, “0006mm” is recorded as the X-axis coordinate, “0003mm” is recorded as the Y-axis coordinate, and the Z-axis is recorded in the element number “E000002”. “0003 mm” is recorded as the coordinates, and “PID ******” is recorded as the belonging part number.

  Here, the element (hereinafter referred to as E) is obtained by dividing the vehicle body α, which is the analysis target area, into a finite number in the stress analysis using the finite element method. It is defined as a triangle or a quadrangle by connecting nodes. The X-axis coordinate in FIG. 6 is the arithmetic mean value of the X-axis coordinates of all the nodes that define the element, and the Y-axis coordinate is the arithmetic mean of the Y-axis coordinates of all the nodes that define the element. The value, Z-axis coordinates, is an arithmetic mean value of the Z-axis coordinates of all the nodes that define the element. In this case, the X-axis coordinates, Y-axis coordinates, and Z-axis coordinates are coordinates on the X-axis, Y-axis, and Z-axis in the area database 24 of FIG. 4, that is, the X-axis and Y-axis shown in FIG. Above, coordinates on the Z axis.

  In short, the element database 25 shown in FIG. 6 records the position of the element E for each element E obtained by dividing the vehicle body α, which is the analysis target area, into a finite number of elements E.

  In this case, the element E is finer than the section K, and one section K is a set of a plurality of elements E ... E.

  Next, as shown in FIG. 7, the stress database 26 has a structure in which stress (MPa) is recorded using an element number as a key. According to the illustrated example, the element number “E000001” is recorded with “123 MPa” as the stress, and the element number “E000002” is recorded with “128 MPa” as the stress.

  Here, the stress is calculated for each element E by setting a load condition, material characteristics and the like in stress analysis using a finite element method.

  In short, the stress database 26 shown in FIG. 7 records the stress (value) calculated for each element E obtained by dividing the vehicle body α, which is the analysis target area, into a finite number of elements E.

  Next, as shown in FIG. 8, the area element correspondence table 27 has a structure in which an element number and stress (MPa) are recorded using the area number as a key. According to the example in the figure, the area number “K0001” is recorded with “E000001” as the element number, “123 MPa” as the stress, “E000002” as the element number, “128 MPa” as the stress, and the like. In “K0002”, an element number “E000101”, a stress “119 MPa”, an element number “E000102”, a stress “106 MPa”, and the like are recorded.

  Here, in the area element correspondence table 27 shown in FIG. 8, the elements E... E are arranged in ascending order of element numbers in each area K. As a result, the element E having the smallest number in each area K is displayed. It is shown first. On the other hand, the stress is randomly arranged regardless of the magnitude of the value.

  In short, the area element correspondence table 27 shown in FIG. 8 includes the data related to the area K recorded in the area database 24 shown in FIG. 4 and the data related to the element E recorded in the element database 25 shown in FIG. Therefore, the section K and the elements E ... E included in the section K are recorded in association with each other.

  Next, as shown in FIG. 9, the maximum stress selection table 28 has a structure in which a stress (MPa) and an element number are recorded using an area number as a key. According to the illustrated example, the zone number “K0001” has “157 MPa” as the stress and the element number “E000056”, and the zone number “K0002” has the stress as “124 MPa” and the element number. "E000127" is recorded.

  Here, in the maximum stress selection table 28 shown in FIG. 9, only the stress having the largest value in each section K and its element number are shown. In the maximum stress selection table 28, for example, in the area element correspondence table 27 shown in FIG. 8, the values of stress are sorted for each area K, and the record indicated first is read and written (transcribed). Can be obtained.

  In short, the maximum stress selection table 28 shown in FIG. 9 includes the maximum stress recorded in the stress database 26 shown in FIG. 7 for each zone K recorded in the zone element correspondence table 27 shown in FIG. The element E for which the stress is calculated is recorded.

  Next, an example of a specific operation performed by the stress analysis apparatus 1 shown in FIG. 1 will be described with reference to the flowchart shown in FIG.

  First, in step S1, CAD data is created for each evaluation reference vehicle and development vehicle.

  Next, in step S 2, the created CAD data is recorded in the CAD database 23. That is, the CAD database 23 of FIG. 3 records a three-dimensional CAD image of the car body α of the automobile, which is the analysis target area, as illustrated in FIG. 5 for each evaluation reference car and each developed car.

  Next, in step S3, the analysis target area α is divided into a plurality of sections K.

  Next, in step S 4, data relating to the divided area K is recorded in the area database 24. That is, the range of the zone K as exemplified in FIG. 5 (X-axis range, Y-axis range, Z-axis range) is recorded in the zone database 24 of FIG. 4 for each zone K... K divided in step S3. I will keep it.

  Next, in step S5, the analysis target area α is divided into a finite number of elements E. That is, in the stress analysis using the finite element method, a large number of nodes (hereinafter referred to as “n”: refer to FIG. 11) are set in the vehicle body α that is the analysis target region, and these nodes n. The vehicle body α is divided into a finite number of elements E... E, and the element E is divided.

  Next, in step S <b> 6, data related to the divided element E is recorded in the element database 25. That is, in the element database 25 of FIG. 6, for each element E... E divided in step S5, the position of the element E (X-axis coordinate, Y-axis coordinate, Z-axis coordinate) and the number of the part to which the element E belongs. Is recorded.

  Next, in step S7, stress is calculated for each element E for the evaluation reference vehicle and the development vehicle. That is, in the stress analysis using the finite element method, load conditions, material characteristics, and the like are set, and the stress is calculated for each element E. This stress calculation process is performed.

  Next, in step S <b> 8, the calculated stress (value) is recorded in the stress database 26. That is, the stress (value) calculated in step S7 is recorded for each element E ... E in the stress database 26 of FIG.

  Next, in step S9, elements E... E included in the section K are extracted for each section K for the evaluation reference vehicle and the development vehicle. That is, based on the range of the area K recorded in the area database 24 of FIG. 4 in the step S4 and the position of the element E recorded in the element database 25 of FIG. Elements E... E included in the area K are extracted.

  Next, in step S <b> 10, the correspondence between the zone K and the element E is recorded in the zone element correspondence table 27. That is, the elements E... E (element numbers) extracted in step S9 and their stresses are recorded for each section K in the section element correspondence table 27 of FIG.

  Next, in step S11, a middle plate element exclusion process of the three-plate spot welded portion is performed. In this process, when selecting the element E having the maximum stress in the next step S12, the element E belonging to the middle plate where the three plates are overlapped and spot-welded is excluded. Even if the maximum stress occurs in the zone K, the element E belonging to the middle plate of the part spot-welded by overlapping the plates is not considered for design change or improvement based on the analysis result. This exclusion process has the following significance.

  That is, the middle plate where the three plates are overlapped and spot-welded is sandwiched between the upper and lower plates even if stress concentration occurs and breaks at the welded portion, etc., so there is a relative problem. Few. Rather than that, it is more important to grasp whether the maximum stress is generated on the upper and lower plates which are scattered when broken or the like and have a problem in terms of appearance and physical properties. Therefore, when selecting the element E that generates the maximum stress in the next step S12, by removing the element E belonging to the middle plate, the information is surely developed when the maximum stress is generated on the upper and lower plates. It will be communicated to the person in charge.

  Further, by excluding unnecessary elements E in this way, there is an advantage that the number of data when selecting the element E that generates the maximum stress in the next step S12 is reduced, and the selection is facilitated.

  Here, with reference to FIG. 11, an example of a specific operation for identifying such an element E when excluding the element E belonging to the middle plate of the spot welded portion where three plates are overlapped will be described. .

  In FIG. 11, P1, P2, and P3 indicated by chain lines indicate three stacked plates, and symbol A indicates a spot weld. In such a case, the spot welded portion A is generally selected as one node n when the elements Ep1, Ep2, and Ep3 are set on the upper plate P1, the middle plate P2, and the lower plate P3, respectively (indicated by white circles in the figure). ). On the other hand, the other nodes n (indicated by black circles) are arbitrarily selected when the elements Ep1, Ep2, and Ep3 are set on the upper plate P1, the middle plate P2, and the lower plate P3, respectively.

  Therefore, in the case of the illustrated example, one node n (white circle) that defines the element Ep1 of the upper plate P1, one node n (white circle) that defines the element Ep2 of the middle plate P2, and the element of the lower plate P3 One node n (white circle) that defines Ep3 has the same X coordinate and Y coordinate, but only the Z coordinate. On the other hand, another node n (black circle) that defines the element Ep1 of the upper plate P1, another node n (black circle) that defines the element Ep2 of the middle plate P2, and an element Ep3 of the lower plate P3 are defined. X coordinate, Y coordinate, and Z coordinate are all different from other nodes n (black circles).

  From such conditions, it can be determined that the element Ep1, the element Ep2, and the element Ep3 are elements E belonging to the three plates P1, P2, and P3 of the spot welded portion, respectively. In the case of the illustrated example, the element Ep2 belonging to the intermediate plate P2 can be identified from the Z coordinates of the nodes n... N that define the element E.

  Returning to FIG. 10, next, in step S <b> 12, the elements E. That is, for each zone K recorded in the zone element correspondence table 27 in FIG. 8 in step S10, the stress values are sorted and the record indicated first is read.

  Next, in step S <b> 13, the selected result is recorded in the maximum stress selection table 28. That is, the record read in step S12 is written for each section K in the maximum stress selection table 28 in FIG. 9, and thereby, the step S12 in each section K in the maximum stress selection table 28 in FIG. The stress selected in step 1 and its element E (element number) are recorded.

  Next, in step S14, processing for creating an image representing the stress analysis result obtained in the above step S13 is executed. In step S15, the image created in step S14 is displayed on the display screen of the output unit 40. Is executed.

  Next, in step S16, the person in charge of development who operates the stress analysis apparatus 1 looks at the image displayed on the screen in step S15, determines that the design change is required for the developed vehicle, and a predetermined predetermined value associated therewith. When the operation is performed on the stress analyzer 1 via the input unit 30, the process returns to step S1. On the other hand, when it is determined that the design change is unnecessary and a predetermined operation associated therewith is performed on the stress analysis apparatus 1 via the input unit 30, the process ends.

  Here, in the above, steps S1 to S13, S15, and S16 are achieved by the stress analysis program 21 shown in FIG. 2, and step S14 is achieved by the drawing program 22 shown in FIG.

  Next, a specific example of an image displayed on the screen in step S15 will be described with reference to FIGS.

  First, FIG. 12 is an example of an image in which a plurality of sections K... K are displayed on one screen W1, and the value of the maximum stress in the section K is displayed as a representative value for each section K. . In the figure, reference numerals 51 and 52 denote a lower plate and an upper plate spot-welded at a plurality of portions A. In addition, the illustrated example is for “evaluation reference car No. 1”.

  If one area K is selected on this screen W1 and the enlarge button is pressed, the screen is switched to a screen W2 in which only the area K is enlarged and displayed as shown in FIG. The illustrated example is for the area number “K0345”.

  In this enlarged screen W2, a stress distribution diagram in the selected section K is displayed, and the value of the maximum stress in the section K (“207 MPa” in the example) and the element E in which the maximum stress occurs are displayed. The number (“E123456” in the example) is displayed simultaneously with characters. Further, as indicated by the symbol a in the figure, in the stress distribution diagram, the display color of the element E in which the maximum stress is generated is darkened, and the element E is highlighted than the other elements E. As a result, the maximum stress in the zone K and the position of the element E where the maximum stress is generated can be grasped simultaneously.

  Further, in the stress distribution diagram of the enlarged screen W2, the elements E ... E are displayed in different colors based on the stress. Thereby, the whole stress distribution in this area K can be grasped at a glance by the difference in color.

  If a return button is pressed on this screen W2 and a predetermined operation is performed, as shown in FIG. 14, a similar area K (see FIG. 14) for another analysis target area α (“development car 1” in the example). In the example, the screen is switched to the screen W3 in which the same area “K0345”) is enlarged and displayed.

  In this screen W3, the shape of the upper plate 52 has been changed as indicated by reference character “A” and a spot welding site A has been added as indicated by reference character “a” as compared with “evaluation reference vehicle No. 1”. . As a result, the value of the maximum stress changes (“287 MPa” in the example), and the number of the element E that generates the maximum stress also changes (“E123478” in the example). Along with this, as indicated by the symbol b in the figure, the display color is darkened, and the position of the highlighted element E is also changed.

  If a comparison button is pressed on this screen W3 and a predetermined operation is performed, two different analysis target areas α (“evaluation reference car No. 1” and “development car No. 1” in the example shown in FIG. 15). ”), A similar area K (the same area“ K0345 ”in the example) is switched to a screen W4 in which the value of each maximum stress and the number of the element E where the maximum stress is generated are displayed side by side.

  As described above, in the present embodiment, the analysis target region α is divided into a finite number of elements E (step S5), and stress is calculated for each divided element E (step S7). In the stress analysis using the method, the analysis target region α is divided into a plurality of sections K composed of a set of a plurality of elements E (step S3), and the section K and the elements E included in the section K are associated with each other. The element E having the maximum stress is selected for each recorded area K (step S12), and the stress of the selected element E is the value of the area K in which the element E is included ( It is output as a representative value (step S15).

  As a result, the developer in charge of operating the stress analyzer 1 sees the analysis result (stress distribution indicating the stress calculated for each element E) on the screen and It is not necessary to perform a very time-consuming and complicated operation such as finding the maximum stress in each section K obtained by dividing the analysis target region α into a plurality of data. Instead, the developer is output on the screens W1 to W4 even if the analysis target area α is relatively large or even if the number of elements E is relatively large in order to improve analysis accuracy. It is possible to easily grasp the maximum stress in each section K by looking at the measured value (representative value), in other words, to easily find the value of the maximum stress from the analysis result.

  Further, since the position of the selected element E is also output on the screens W2 to W4, not only the maximum stress but also position information indicating which element E has the maximum stress calculated is output. The developer in charge looks at the output representative value and the position of the element E on the screens W2 to W4, and simultaneously determines the maximum stress in each section K and the portion where the maximum stress occurs. It is possible to easily grasp, in other words, it is possible to easily find the value of the maximum stress and the place where the stress occurs from the analysis result at the same time.

  Further, since the stress distribution in which each element E is color-coded based on the calculated stress is displayed on the screens W2 to W4, the maximum stress and the position of the element E are displayed. On the W4, it is possible to see the color distribution of the stress distribution and grasp the entire stress distribution in each section K at a glance by the difference in color.

  Further, on the screen W4, the maximum stress and the position of the element E are displayed side by side for a similar area K between a plurality of different analysis target regions α. By looking at a plurality of displayed maximum stresses and position information, it is easy to compare and compare the analysis results of similar areas K of different articles such as the reference vehicle and the development vehicle, and design based on the analysis results It will greatly contribute to changes and improvements.

  Although the above embodiment is the best embodiment of the present invention, various changes and improvements can still be made without departing from the scope of the claims. For example, in the above-described embodiment, the section is a section where the space in which the analysis target area exists is regularly divided into a plurality of sections, but the section may be an area occupied by a plurality of parts constituting the analysis target area. In this case, the element included in the part is recorded in association with each part, the element of the maximum stress is selected for each part, and the maximum stress and the element selected for each part are output.

  In the above embodiment, the maximum stress and the element number are displayed separately from the stress distribution diagram on the screens W2 to W4 in FIGS. 13 to 15, but the maximum stress and the element number are displayed on the stress distribution diagram. It is preferable that the display is overlapped at the position of the element because it is easier to grasp.

  As described above in detail with specific examples, the present invention is a technique that can easily find the value of the maximum stress and the location where the stress occurs from the analysis result in the stress analysis using the finite element method. For example, a wide range of industrial applicability is expected in the technical field of new car development in the automobile industry.

1 is an overall configuration diagram of a stress analysis apparatus according to the best embodiment of the present invention. It is a conceptual diagram which shows the structure of the recording part of the said stress analyzer. It is a conceptual diagram which shows the structure of the CAD database stored in the said recording part. It is a conceptual diagram which similarly shows the structure of an area database. It is a conceptual diagram which shows the relationship between the three-dimensional CAD image of the vehicle body which is an analysis object area | region, and an area, (a) is a front view, (b) is a top view, (c) is a side view. It is a conceptual diagram which shows the structure of the element database stored in the said recording part. It is a conceptual diagram which similarly shows the structure of a stress database. It is a conceptual diagram which similarly shows the structure of an area element corresponding | compatible table. It is a conceptual diagram which similarly shows the structure of the maximum stress selection table. It is a flowchart which shows an example of the specific operation | movement which the said stress analyzer performs. It is a conceptual diagram explaining an example of the specific operation | movement which identifies the element which belongs to the intermediate | middle board of the site | part which carried out spot welding of 3 sheets of plates. It is explanatory drawing of the image which the said stress analyzer displays a stress analysis result on a screen. It is explanatory drawing of another image similarly. It is explanatory drawing of another image. It is explanatory drawing of another image.

Explanation of symbols

1 Computer system (stress analyzer)
DESCRIPTION OF SYMBOLS 10 Control part 20 Recording part 30 Input part 40 Output part 24 Area database 25 Element database 27 Area element corresponding | compatible table 28 Maximum stress selection table alpha Car body (analysis object area | region)
E element K area n node S3 3rd step (classification means)
S7 7th step (calculation means)
S10 10th step (recording means)
S12 12th step (selection means)
S15 15th step (output means)
W1-W4 screen

Claims (6)

An apparatus for analyzing stress using a finite element method,
A calculation means for dividing the analysis target region into a finite number of elements and calculating stress for each element;
Classifying means for dividing the analysis target area into a plurality of areas composed of a set of a plurality of elements,
A recording means for recording the area divided by the sorting means and the elements included in the area in association with each other;
A selecting means for selecting an element having the maximum stress calculated by the calculating means for each area recorded by the recording means; and
The stress of the selected element in the selection means have a output means for outputting a value of the area that contains the element,
The output means outputs the position of the element selected by the selection means together . In the stress analysis apparatus according to claim 1,
The output means outputs the stress and the position by displaying the stress and position of the element selected by the selection means on a screen . In the stress analysis apparatus according to claim 2 ,
The output means displays the stress and the position on the screen while displaying on the screen a stress distribution in which each element is color-coded based on the stress calculated by the calculating means . In the stress analysis apparatus according to claim 2 or 3 ,
The calculation means, for each of a plurality of different analysis target areas, each divided into a finite number of elements to calculate the stress for each element,
The dividing means divides each analysis target area into a plurality of sections each consisting of a set of a plurality of elements,
The recording means records each area to be analyzed in association with the area divided by the dividing means and the elements included in the area,
The selection unit selects an element having the maximum stress calculated by the calculation unit for each area recorded by the recording unit for each analysis target region,
The output means displays the stress and the position of the element selected by the selection means side by side on a screen in a similar area between the analysis target areas . In the stress analysis apparatus according to any one of claims 1 to 4 ,
The stress analysis apparatus according to claim 1, wherein the selecting means excludes an element belonging to a middle plate of a portion spot-welded by overlapping three plates and selects an element having the maximum stress. A method of analyzing stress in a computer system using a finite element method,
The computer system is
A calculation step of dividing the analysis target area into a finite number of elements and calculating stress for each element;
A division step of dividing the analysis target area into a plurality of areas composed of a set of a plurality of elements;
A recording step for recording the areas classified in this classification step in association with the elements included in the areas;
A selection step for selecting an element having the maximum stress calculated in the calculation step for each area recorded in the recording step; and
An output step of outputting the stress of the element selected in this selection step as a value of an area including the element;
In the output step, stress analysis wherein the outputs together the position of the selected in the selection step element.

Images