JP2006202094A - Structural analysis model preparation system of body panel for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically and accurately prepare a structural analysis model divided with meshes having substantially uniform shapes and sizes based on CAD data of a structural analysis object. <P>SOLUTION: The structural analysis model preparation system comprises a closed shape detection means 9 for detecting a shape line constituting a closed shape based on the CAD data, a shape line data storage means 11 for storing data of the shape line constituting the closed shape detected by the closed shape detection means 9, a specific line determining means 10 that determines whether the shape line recognized not to constitute the closed shape by the closed shape detection means 9 is a specific line that is not required in structural analysis, deletes the data of the specific line when it is determined that it is the specific line, and makes the data stored in the shape line data storage means 11 when it is determined that it is not the specific line, and a mesh data preparation means 12 for preparing mesh data of the structural analysis object based on the data of the shape stored in the shape line data storage means 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle body panel structural analysis model creation system that automatically creates a structural analysis model divided by a mesh based on CAD data of a structural analysis object.

  Conventionally, as shown in Patent Document 1 below, an input unit that inputs an arbitrary line element corresponding to the drawing of the structural analysis object, an intersection calculation unit that calculates an intersection point between the line elements and sets the intersection point data, A line generation data is calculated from the adjacent intersections with respect to the line element, and a mesh generation unit for generating mesh data from the line segment data and the intersection data is provided, and the intersection from the line element arbitrarily input using the above input means In other words, mesh data is generated by extracting line segment data.

Further, in Patent Document 2 below, structural analysis shape data, which is an aggregate of a plurality of line data corresponding to each of the above lines, is obtained with respect to CAD data of a structural analysis target whose shape is defined by a combination of a plurality of lines. An apparatus that automatically generates a structural analysis model that is mesh-divided into a plurality of elements by calculating and processing the shape data based on a program, and independent end points that do not share a plurality of lines from the shape data The CAD data is converted into data that can be processed by a program for generating a structural analysis model by expanding and contracting an independent line having this independent end point in the extending direction and bringing it into contact with another line. When an abnormality such as separation of the end points of each line segment that should be in contact with each other occurs, this is automatically corrected to properly form the structural analysis model And it is configured to kill.
JP 7-44525 A JP 2004-145718 A

  As disclosed in Patent Documents 1 and 2 above, shape data for structural analysis is extracted from intersection data and line segment data read from CAD data, and a finite element method or the like is performed based on the shape data. When configured to automatically create mesh data used for numerical analysis, the shape data for forming the mesh data is compared to that manually input by the user using a keyboard, etc. There is an advantage that mesh data used for structural analysis of a vehicle body panel or the like can be easily created.

  However, when a vehicle body panel having a complicated shape in which a large number of curved surfaces or the like are combined is used as a structural analysis object, a large amount of data such as shape lines representing the boundary portion of the curved surface is included in the CAD data. Therefore, when mesh data is automatically created based on the CAD data, a structural analysis model in which meshes having various shapes and sizes are combined in a complex manner is formed. Therefore, when performing numerical analysis such as the finite element method based on this structural analysis model, there are problems such as an increase in calculation time and an inability to obtain an accurate structural analysis result.

  In order to prevent the above adverse effects and to be able to form a model for structural analysis divided by a mesh having a uniform shape and size, the shape line necessary for mesh formation is left from the CAD data, and an unnecessary shape It is also conceivable that the line is erased by manual operation of the operator or automatic operation of the structural analysis model creation system. However, when configured in this way, it is difficult to accurately determine whether or not the shape line is necessary for mesh formation based on the CAD data, and the shape required for mesh formation is difficult. There are problems such as lines being erased accidentally and unnecessary shape lines being left behind.

  The present invention has been made in view of the above problems, and based on CAD data of a structural analysis object, a structural analysis model divided by a mesh having a substantially uniform shape and size is automatically and accurately determined. It is an object of the present invention to provide a vehicle body panel structural analysis model creation system that can be created.

  The invention according to claim 1 is a structural analysis model creation system for a vehicle body panel that automatically creates a structural analysis model divided by a mesh based on CAD data of a structural analysis object. Closed shape detecting means for detecting a shape line constituting a closed shape based on the above, a shape line data storage means for storing data of a shape line constituting the closed shape detected by the closed shape detecting means, and the closed shape detection It is determined whether or not a shape line that is considered not to constitute a closed shape by means is a specific line that is not necessary for structural analysis, and if it is determined to be a specific line, the data is erased, Based on the shape line data stored in the shape line data storage means and the specific line determination means for storing the data in the shape line data storage means when it is determined that the line is not a specific line. There are those with a mesh data creation means for creating a mesh data structure analysis object.

  According to a second aspect of the present invention, in the structural analysis model creation system for a vehicle body panel according to the first aspect, the closed shape detecting means may cause a continuous shape line starting from an arbitrary point to return to the starting point. When it is confirmed, it is determined that this shape line constitutes a closed shape.

  According to a third aspect of the present invention, in the structural analysis model creation system for a vehicle body panel according to the second aspect, the closed shape detecting means may cause a continuous shape line starting from an arbitrary point to return to the starting point. Even if it is confirmed, when it is confirmed that the length of the shape line is less than a preset reference length, the shape line is regarded as not constituting a closed shape. .

  According to the first aspect of the invention, the various shapes constituting the vehicle body panel based on the CAD data of the structural analysis object composed of the vehicle body panel having a complicated shape in which a large number of curved surfaces are combined. Select the shape line data that constitutes the closed shape from the lines, and select the shape lines that do not constitute the closed shape as required for structural analysis and those that are not required for unnecessary analysis. Since it is configured to erase line data, it can automatically and accurately create a structural analysis model divided by a mesh with a uniform shape and size based on only the shape lines necessary for structural analysis. It is possible to effectively reduce the calculation time when performing numerical analysis such as the finite element method according to this structural analysis model, and to perform accurate structural analysis. There is an advantage in that.

  According to the second aspect of the present invention, when it is confirmed that a continuous shape line starting from an arbitrary point returns to the start point, it is determined that the shape line constitutes a closed shape. Therefore, based on the shape line data extracted from the CAD data, the closed shape detecting means can automatically and accurately determine whether or not the shape line constitutes a closed shape.

  According to the invention of claim 3, even when the closed shape detecting means confirms that a continuous shape line returns to the start point from any one point as a start point, the length of the shape line is set in advance. When it is confirmed that the length is less than the length, the shape line is regarded as not constituting a closed shape, and the data is prevented from being stored in the shape line data storage means. Therefore, even though the area of the closed shape partitioned by the shape line is significantly smaller than that of the standard size mesh, the adverse effect of storing the shape line data in the shape data storage means, that is, the standard There is an advantage that it is possible to automatically prevent the occurrence of a situation in which an extremely small mesh is formed in the closed shape compared to the mesh of the size.

  FIG. 1 is a block diagram showing an embodiment of a structural analysis model creation system for a vehicle body panel according to the present invention. The vehicle body panel structural analysis model creation system includes a control unit 2 for automatically creating a structural analysis model divided by a mesh based on CAD data input from the CAD apparatus 1, and the control unit 2. An input means comprising a keyboard 3 and a mouse 4 for inputting a predetermined command signal, and an output means comprising a CRT 5 for displaying image information etc. output from the control unit 2 or a printer 6 for printing this image information etc. And have.

  The structural analysis object created by the control unit 2 based on the CAD data of the structural analysis object inputted to the control unit 2 from the CAD device 1, that is, the vehicle body panel having a complicated shape in which a large number of curved surfaces are combined. The mesh data of the model is input to the structural analysis device 7, and the structural analysis of the vehicle body panel using the finite element method or the like is executed in the structural analysis device 7. The input means including the keyboard 3 and the mouse 4 has a function of inputting a designation signal for designating a standard mesh size and shape when creating mesh data, and a control for creating the data. The unit 2 has a function of inputting a correction signal or the like for correcting a shape line for creating mesh data obtained by processing CAD data.

  The control unit 2 includes a CAD data storage unit 8 that stores CAD data input from the CAD device 1 and a closed unit that detects a shape line that forms a closed shape from the CAD data stored in the CAD data storage unit 8. A shape detection unit 9, a shape line data storage unit 11 for storing data of a shape line detected by the closed shape detection unit 9, and a shape line regarded as not forming a closed shape by the closed shape detection unit 9 It is determined whether or not a specific line is not necessary for structural analysis, the shape line data determined to be a specific line is deleted, and the other shape line data is stored in the shape line data. Specific line determination means 10 to be stored in the means 11, mesh data creation means 12 to create mesh data based on the shape line data stored in the shape line data storage means 11, and It is provided.

  The closed shape detection means 9 appropriately extracts continuous shape line data starting from an arbitrary point from the CAD data stored in the CAD data storage means 8, and determines whether or not this shape line returns to the start point. By doing so, a shape line constituting the closed shape is detected. For example, as shown in FIG. 2, when the shape line L1 is traced starting from one point P1 of the shape line L1 and this shape line L1 has a branch point P2, the shape line L1a already traced A smoothly continuous shape line, that is, a shape line L1b having a branch angle close to 180 ° with respect to the shape line L1a is selected, and the operation of tracing the data of the shape line L1b is repeated. When it is confirmed that the shape line L1 returns to the starting point P1, the shape line L1 is considered to constitute a closed shape in principle, and the data is stored in the shape line storage means 11. It has become so.

  On the other hand, based on the shape line data extracted from the CAD data storage means 8, it is confirmed that there is no smoothly continuous shape line when the shape line has a branch point, or When the closed shape detection means 9 detects that the shape line does not constitute a closed shape, for example, by confirming that it does not return, the data of the shape line is input to the specific line determination means 10. Whether the line is a specific line is determined.

  For example, when the branch line L3 branched from the shape line L1 constituting the closed shape at the branch point P2 is not considered to constitute the closed shape in FIG. It is determined whether or not the shape line formed by the branch line L3 is a specific line by determining whether or not L3 is a ridge line of the continuous surfaces F1 and F2 that are gently continuous.

  Specifically, when it is confirmed that the connection angle of the continuous surfaces F1 and F2 connected at the branch line P2 is within a range of 170 ° to 190 °, the branch line L3 performs structural analysis. It is determined that the specific line is unnecessary, and the data is erased without being stored in the shape line storage unit 11. The connecting angle between the continuous surfaces F1 and F2 is not within the range of 170 ° to 190 °, and the branch line L3 shown in FIG. 2 is a ridge line or the like of the continuous surfaces F1 and F2 that are continuous at a steep angle. When confirmed by the specific line determination means 10, the branch line L 3 is regarded as not a specific line, and the data is stored in the data storage means 11.

  The mesh data creation means 12 is the shape line data stored in the shape line data storage means 11, that is, the shape line data detected by the closed shape detection means 9 as a shape line constituting a closed shape, and Based on the shape line data that does not constitute a closed shape and is regarded as not a specific line by the specific line detection means 12, the area defined by these shape lines is designated in advance by the input means. Mesh data (see FIG. 3) to be divided by the mesh M corresponding to the standard size and shape is created, and this mesh data is input to the structural analysis device 7.

  The control operation by the control unit 2 will be described based on the flowchart shown in FIG. When this control operation starts, first, the shape line data constituting the structural analysis object is appropriately extracted from the CAD data stored in the CAD data storage means 8 (step S1). By analyzing the data of continuous shape lines starting from one point, it is determined whether or not this shape line has a branch point (step S2).

  If it is determined NO in step S2 and it is confirmed that the shape line does not have a branch point, by tracing the data of the shape line, whether or not the end point coincides with the start point, that is, It is determined whether or not the shape line returns to the starting point (step S3). If it is determined YES in step S3 and it is confirmed that the start point and the end point of the shape line coincide with each other, whether or not the total length L of the shape line is equal to or larger than a preset reference length R. Is determined (step S4). If YES is determined in step S4 and it is confirmed that the total length L of the shape line is equal to or greater than the reference length R, the data of the shape line is stored in the data storage unit 11 (step S5).

  The reference length R is set to a value corresponding to the total length of the standard size mesh specified by the input means including the keyboard 3, etc., and the closed shape partitioned by the shape line is suitable for creating a mesh. It is discriminate | determined whether it has an area. In addition, when it determines with NO by the said step S4 and it is confirmed that the full length L of a shape line is less than the said reference length R, it will be considered that the said shape line does not comprise a closed shape. It transfers to following step S7 and determination whether the said shape line is a specific line is performed.

  On the other hand, when it is determined YES in Step S2 and it is confirmed that the shape line has a branch point, there is a smooth branch line having a branch angle in the range of 170 ° C. to 190 °. (YES in step S6), if YES is determined, the process proceeds to step S3 to determine whether or not the end point of the branch line coincides with the start point.

  Moreover, it is determined as NO in step S6 and it is confirmed that there is no smooth branch line having a branch angle in the range of 170 ° C. to 190 °, or the end point of the shape line does not coincide with the start point in step S3. If it is confirmed in step S4 that the total length L of the shape line is less than the reference length R, whether or not the shape line is a specific line in step S7. A determination is made. If it is determined YES in step S7 and it is confirmed that the shape line is a specific line that is not necessary for structural analysis, that is, the shape line is a ridge line of a continuous surface that is gently continuous, the shape After deleting the line data without storing it in the shape line data storage means 11 (step S8), the process proceeds to the following step S9.

  On the other hand, it is determined as NO in the above step S7, and the shape line is not a specific line that is not necessary for structural analysis, that is, the ridge line of the continuous surface where the shape line continues at a steep angle, etc. If it is confirmed that the line is a necessary line, the process proceeds to step S5, and the shape line data is stored in the shape line data storage unit 11. Next, it is determined whether or not the detection of all the shape lines constituting the structural analysis object stored in the CAD data storage means 8 has been completed (step S9). If NO is determined, the step S1 is performed. The above control operation is repeated after returning to step S2.

  When it is determined as YES in step S9 and it is confirmed that the detection of the shape lines constituting the structural analysis object is completed, the CRT 5 displays the image information of the structural object constituted by the shape lines. At the same time, an unnecessary shape line is deleted or a correction to add a necessary shape line is performed as necessary by a manual operation using the input means based on the image information (step S10). Then, the mesh data creating means 12 automatically creates the mesh data based on the shape line data stored in the shape line data storage means 11 and outputs the mesh data to the structural analysis device 7 (step S11), the control operation is terminated.

  As described above, the closed shape detecting means 9 for detecting the shape line constituting the closed shape based on the CAD data stored in the CAD data storage means 8 and the closed shape detected by the closed shape detecting means 9 are configured. It is determined whether or not a shape line that is considered not to constitute a closed shape by the shape line data storage means 11 for storing shape line data and the closed shape detection means 9 is a specific line that is not necessary for structural analysis. If it is determined that the data is a specific line, the data of the specific line is deleted, and if it is determined that the data is not a specific line, the data is stored in the shape line data storage unit 11. And the mesh data creating means 12 for creating the mesh data of the structural analysis object based on the shape data stored in the shape line data storage means. Based on the CAD data of the structural analysis object consisting of Le, a structural analysis model which is divided by a mesh having a substantially uniform shape and size can be created automatically and accurately.

  That is, from the various shape lines constituting the vehicle body panel having a complicated shape in which a large number of curved surfaces are combined, for example, data on the shape line constituting the closed shape as shown in L1 of FIG. A shape line that is selected and stored in the shape line data storage means 11 and that does not constitute a closed shape is classified into those that are required in structural analysis and those that are not required, and unnecessary shape lines, for example, As shown by the branch line L3 in FIG. 2, data such as ridge lines of the continuous surfaces F1 and F2 that are gently continuous are erased. For this reason, as shown in FIG. 3, the shape line L1 that forms the closed shape necessary for performing the structural analysis of the structural analysis object, and the ridge lines of the continuous surfaces F1 and F2 that are continuous at a steep angle are formed. The shape line L2 can be stored in the shape line data storage means 11. Therefore, a structural analysis model divided by the mesh M having a uniform shape and size can be automatically and appropriately created based on only the shape lines L1 and L2 necessary for structural analysis. According to the analysis model, there are advantages that the calculation time for performing the numerical analysis such as the finite element method can be effectively shortened and the accurate structural analysis can be performed.

  Further, in the above embodiment, when it is confirmed that a continuous shape line L1 starting from an arbitrary point P1 returns to the start point, it is determined that the shape line L1 constitutes a closed shape. Therefore, based on the data of the shape line L1 extracted from the CAD data, the closed shape detection means 9 can automatically and accurately determine whether or not the shape line L1 constitutes a closed shape. it can.

  Further, in the above embodiment, even when the closed shape detecting means 9 confirms that the continuous shape line L1 starting from an arbitrary point P1 returns to the start point, the total length L of the shape line L1 is set in advance. When it is confirmed that the shape line L1 does not constitute a closed shape when it is confirmed that the length is less than the reference length R, the area of the closed shape defined by the shape line L1 is a standard size. The shape line data can be prevented from being stored in the shape data storage means 11 even though it is remarkably smaller than the mesh. Therefore, it is possible to prevent the occurrence of a situation in which an extremely small mesh is formed inside the closed shape compared to a standard size mesh due to the extremely small area of the closed shape defined by the shape line L1. There is an advantage that you can.

1 is a block diagram showing an embodiment of a structural analysis model creation system for a vehicle body panel according to the present invention. It is explanatory drawing which shows an example of the shape line read from CAD data. It is explanatory drawing which shows the specific example of a structural analysis model. It is a flowchart which shows an example of the control action which produces a structural analysis model.

Explanation of symbols

9 Closed shape detection means 10 Specific line determination means 11 Shape line data storage means 12 Mesh data creation means

Claims (3)

  A vehicle body panel structural analysis model creation system for automatically creating a structural analysis model divided by a mesh based on CAD data of a structural analysis object, wherein the shape forms a closed shape based on the CAD data Closed shape detection means for detecting a line, shape line data storage means for storing data of a shape line constituting the closed shape detected by the closed shape detection means, and a closed shape constituted by the closed shape detection means If it is determined that the shape line considered to be non-specific is a specific line that is not necessary for structural analysis, and if it is determined to be a specific line, the data is deleted, and if it is determined not to be a specific line Specific line determination means for storing the data in the shape line data storage means, and the data of the shape analysis stored in the shape line data storage means Structural analysis model generation system of a vehicle body panel, characterized in that a mesh data creation means for creating Sshudeta.   The closed shape detecting means, when it is confirmed that a continuous shape line starting from an arbitrary point returns to the start point, it is determined that the shape line constitutes a closed shape. Item 4. The vehicle body panel structural analysis model creation system according to Item 1.   The closed shape detecting means is configured such that the length of the shape line is less than a preset reference length even when it is confirmed that a continuous shape line returns to the start point starting from an arbitrary point. 3. The structure analysis model creation system for a vehicle body panel according to claim 2, wherein the shape line is not considered to constitute a closed shape when the above is confirmed.

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