JP4655640B2 - Vehicle body panel structural analysis model creation system - Google Patents

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-described adverse effects and 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 the operator's manual operation Alternatively, it may be configured to delete unnecessary shape lines by 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. A fillet surface detecting means for detecting a fillet surface in which a pair of fillets are arranged in parallel, a boundary erasing means for detecting a boundary line of the fillet existing in the fillet surface and erasing the data, and the fillet Shape line data storage means for storing the data of the shape line left after the boundary line in the surface is deleted, and the mesh data of the fillet surface based on the shape line data stored in the shape line data storage means And mesh data creation means for creating the.

  The invention according to claim 2 is the vehicle body panel structural analysis model creation system according to claim 1, wherein the arc length of the fillet constituting the fillet surface is less than a preset reference value. Is determined to be less than the reference value, the boundary line of the fillet existing in the fillet surface is detected and the data is erased by the boundary line erasing means.

  According to a third aspect of the present invention, in the vehicle body panel structural analysis model creation system according to the second aspect, a fillet serving as a criterion for determining whether or not the boundary line data is erased by the boundary line erasing means is provided. The arc length is set to a value corresponding to the standard size of the mesh designated by the input means.

  According to the first aspect of the present invention, based on CAD data of a vehicle body panel having a complicated shape in which a large number of curved surfaces are combined, a fillet surface in which a pair of fillets are arranged in parallel is the fillet surface detection. When detected by means, the shape line that forms the boundary line of the fillet existing in the fillet surface is detected and the data is erased. Therefore, the shape that basically constitutes the contour line of the fillet surface Only the line data is stored in the shape line data storage means. Therefore, the occurrence of a situation in which the fillet surface is divided by a remarkably small mesh compared to a standard size mesh due to the fact that a shape line serving as a fillet boundary line remains in the fillet surface. There is an advantage that a structural analysis model in which the fillet surface is divided by a mesh of a predetermined size can be automatically and appropriately created.

  According to the second aspect of the invention, when it is determined whether the arc length of the fillet constituting the fillet surface is less than a preset reference value, and it is confirmed that the fillet surface is less than the reference value. Only when the shape line that is the boundary of the fillet on the fillet surface is detected and the data is deleted, the data of the shape line that does not need to be deleted is prevented, and the mesh of the predetermined size Thus, there is an advantage that the structural analysis model in which the fillet surface is divided can be automatically and appropriately created.

  According to the invention of claim 3, whether or not the arc length of the fillet constituting the fillet surface is less than a reference value set to a value corresponding to the standard size of the mesh specified by the input means. A shape line that does not need to be erased is detected only when it is determined that it is less than the reference value and the shape line that forms the boundary of the fillet existing in the fillet plane is detected and the data is erased. There is an advantage that a structural analysis model in which the fillet surface is divided by a standard size mesh can be automatically and properly created while preventing the data of the above from being erased.

  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.

  Structure generated by the control unit 2 based on the CAD data of the structural analysis object input from the CAD device 1 to the control unit 2, that is, a vehicle body panel having a complicated shape in which a large number of curved surfaces are combined. The mesh data of the analysis model is input to the structure analysis device 7, and the structure analysis of the vehicle body panel using the finite element method or the like is executed in the structure 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 mesh data is created, 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 for storing CAD data input from the CAD device 1 and a fillet in which a pair of fillets are arranged in parallel from the CAD data stored in the CAD data storage unit 8. A fillet surface detecting means 9 for detecting a surface, a boundary line erasing means 10 for detecting a boundary line in the fillet surface detected by the fillet surface detecting means 9 and erasing the data, and the boundary line is erased. The shape line data storage means 11 for storing the data of the shape line of the fillet surface left by this, and the mesh data in the fillet surface is created based on the shape line data stored in the shape line data storage means 11. Mesh data creation means 12 is provided.

  The fillet surface detection means 9 searches for an arbitrary fillet by extracting the shape line data constituting the fillet from the CAD data stored in the CAD data storage means 8, and extends parallel or substantially parallel to the fillet. The fillet surface is detected by searching for another fillet.

  For example, as shown in FIG. 2, when the presence of the first fillet F1a made of a curved surface having a curvature radius R1 is confirmed by data of the shape lines L1 and L2 constituting the upper boundary line and the lower boundary line, etc. Indicates whether there is a second fillet F1b extending parallel to the first fillet F1a at a position close to the first fillet F1a and having a bending direction opposite to that of the first fillet F1a. The determination is made based on the data of the shape lines L2, L4 constituting the lower boundary line. Then, when it is confirmed that there is a second fillet F1b made of a curved surface having a radius of curvature R2 continuous with the first fillet F1a with the lower boundary line of the first fillet F1a as the upper boundary line, It is considered that there is a fillet surface F1 defined by a shape line L1 that is an upper boundary line of the first fillet F1a and a shape line L4 that is a lower boundary line of the second fillet F1b.

  Further, as shown in FIG. 3, the presence of the first fillet F2a formed of a curved surface having a curvature radius R1 is confirmed by data of a pair of upper and lower shape lines L1 and L2 constituting the upper boundary line and the lower boundary line. In addition, the fact that there is a second fillet F2b made of a curved surface with a radius of curvature R2 via a flat surface H1 below the first fillet F2a indicates that the upper boundary line and the lower boundary line of the second fillet F2b are When confirmed based on the data of the shape lines L3, L4, etc., the shape line L1 that is the upper boundary line of the first fillet F2a and the shape line L4 that is the lower boundary line of the second fillet F2b It is considered that a partitioned fillet surface F2 exists.

  The boundary line erasing means 10 has a standard size in which the arc lengths of the first and second fillets F1a, F1b, F2a, and F2b constituting the fillet surfaces F1 and F2 are specified by the input means including the keyboard 3 and the like. When the value is less than the reference value set to the value corresponding to the mesh size, the boundary lines of the first and second fillets F1a, F1b, F2a, F2b existing in the fillet surfaces F1, F2 are detected and the data is obtained. It is configured to erase. The reference value is set to a value corresponding to the size of the standard mesh designated by the input means. For example, when a mesh having a side length of 10 mm is designated as the standard mesh, the side length 70 is set. The reference value is set to about 7 mm which is%.

  In the example shown in FIG. 2, it is confirmed that at least one of the arc lengths A1 and A2 of the first and second fillets F1a and F1b constituting the fillet surface F1 is less than the reference value (about 7 mm). In addition, the boundary line erasing means 10 erases the data of the shape line L2 serving as the lower boundary line of the first fillet F1a and the upper boundary line of the second fillet F1b existing in the fillet surface F1.

  In the example shown in FIG. 3, when it is confirmed that the arc lengths B1 and B2 of both fillets F2a and F2b constituting the fillet surface F2 are less than the reference value (about 7 mm), the fillet surface F2 The boundary line erasing means 10 erases both the data of the shape line L2 that is the lower boundary line of the first fillet F2a and the data of the shape line L3 that is the upper boundary line of the second fillet F1b. It will be.

  As described above, the boundary lines in the fillet surfaces F1 and F2 are deleted, so that the upper boundary line L1 and the second fillets F2a and F2b of the first fillets F1a and F1b constituting the contour lines of the fillet surfaces F1 and F2 are erased. The data of the lower boundary line L4 is left and stored in the shape line data storage means 11.

  In the example shown in FIG. 2, when it is confirmed that both the arc lengths A1 and A2 of the first and second fillets F1a and F1b are equal to or larger than the reference value, the inside of the fillet surface F1. The data of the shape lines L1, L2, and L4, which are the lower boundary line of the first fillet F1a and the upper boundary line of the second fillet F1b existing in FIG. The data is input to the storage means 11 and stored.

  In the example shown in FIG. 3, when it is confirmed that at least one of the arc lengths B1 and B2 of the first and second fillets F2a and F2b is equal to or greater than the reference value, the fillet surface F2 Each shape line is erased without erasing data of one or both of the shape line L2 serving as the lower boundary line of the first fillet F2a and the upper boundary line of the second fillet F2b. The data of L1 to L4 are input to the shape line data storage means 11 and stored. For example, when it is confirmed that the arc length B1 of the first fillet F2a is greater than or equal to the reference value and the arc length B2 of the second fillet F2b is less than the reference value, the second The data of the shape line L3 serving as the upper boundary line of the fillet F2b is erased, and the data of the shape line L2 serving as the lower boundary line of the first fillet F2a is not erased in the shape line data storage means 11. It has come to be remembered.

  The mesh data creating means 12 is the shape line data stored in the shape line data storage means 11, that is, the upper boundary line L1 and the second boundary lines L1 of the first fillets F1a and F1b constituting the contour lines of the fillet surfaces F1 and F2. Based on the data of the lower boundary line L4 of the fillets F2a, F2b, etc., the fillet surfaces F1, F2 partitioned by these boundary lines L1, L4 are divided by a mesh corresponding to the standard size and shape designated in advance by the input means. Mesh data to be generated is input, and the 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, after detecting a fillet surface in which a pair of fillets are arranged in parallel from the CAD data stored in the CAD data storage means 8 (step S1), the arc of the fillet constituting this fillet surface It is determined whether or not the length is less than a preset reference value K (step S2).

  When it is determined YES in step S2 and it is confirmed that a fillet having an arc length less than the reference value K exists, a boundary line existing in the fillet plane is detected and the corresponding boundary is detected. The line data is erased by the boundary line erasing means 10 (step S3). Next, the shape line data left after the boundary line is erased is input to the shape line data storage means 11 and stored (step S4).

  On the other hand, if it is determined NO in step S2 and it is confirmed that there is no fillet having an arc length less than the reference value K, the boundary line erasing means 10 executes the boundary line data erasure. Instead, the process proceeds to step S4, and the data of all the shape lines constituting the fillet surface are input and stored in the shape line data storage means 11, and then the shape line display by the CRT 5 or the like and the shape line by the input means are displayed. Data correction is executed (step S5).

  Actually, by repeating the control operations in steps S1 to S4, the process proceeds to step S5 after the detection of the fillet surface existing in the structural analysis object and the erasing and storing operation of the shape line data are completed. Thus, the shape line data stored in the shape line data storage unit 11 is output to the CRT 5 to display the image of the fillet surface partitioned by the shape line, and the input unit is used based on the image information. An unnecessary shape line is erased by manual operation, or a correction for adding a necessary shape line is executed as necessary (step S5). Then, based on the shape line data stored in the shape line data storage unit 11, the mesh data of the fillet surface is automatically generated by the mesh data generation unit 12, and the mesh data is output to the structural analysis device 7. Later (step S6), the control operation is terminated.

  Fillet surface detecting means 9 for detecting a fillet surface in which a pair of fillets are arranged in parallel based on the CAD data stored in the CAD data storage means 8 as described above, and the boundary line of the fillet existing in the fillet surface Boundary line erasing means 10 for detecting the data and erasing the data, shape line data storage means 11 for storing the data of the shape line left by erasing the boundary line in the fillet plane, and the shape line Since the mesh data creating means 12 for creating the mesh data of the fillet surface based on the shape line data stored in the data storage means 11 is provided, based on the CAD data of the structural analysis object composed of the vehicle body panel, Automatically and accurately create a structural analysis model divided by a mesh with a substantially uniform shape and size It is possible.

  That is, a pair of fillets F1a and F1b are arranged in parallel on the basis of various shape lines constituting the vehicle body panel having a complicated shape in which a large number of curved surfaces are combined, for example, as shown in FIG. In addition, when the fillet surface F1 whose bending direction is set in the reverse direction is detected by the fillet surface detection means 9, the boundary line between the first and second fillets F1a and F1b existing in the fillet surface F1 Since the shape line L2 is detected and the data is erased, the data of the shape lines L1 and L4 constituting the contour line of the fillet surface F1 is stored in the shape line data storage unit 11. .

  Accordingly, as shown in FIGS. 5 (a) and 6 (a), the shape lines L2 and L3 that are the boundary lines of the first and second fillets F1a, F1b, F2a, and F2b in the fillet surfaces F1 and F2. Therefore, the occurrence of a situation where the fillet surfaces F1 and F2 are divided by the mesh M1 that is remarkably smaller than the mesh M of the standard size can be prevented. Then, as shown in FIGS. 5 (b) and 6 (b), the structure analysis model in which the fillet surfaces F1, F2 are divided by a standard-sized mesh M is automatically and appropriately created, whereby the structure There are advantages in that the calculation time when performing numerical analysis such as the finite element method according to the analysis model is effectively shortened and an accurate structural analysis result can be obtained.

  In the above embodiment, is the arc length A1, A2, B1, B2 of the first and second fillets F1a, F1b, F2a, F2b constituting the fillet surfaces F1, F2 less than a preset reference value? If it is determined whether or not it is less than the reference value, the shape line L2, which is the boundary line between the first and second fillets F1a, F1b, F2a, F2b existing in the fillet surfaces F1, F2 Since L3 is detected and its data is erased, there is an advantage that it is possible to prevent erasing of shape line data that does not need to be erased. That is, since the arc lengths A1, A2, B1, and B2 are sufficiently long, even if the shape lines L2 and L3 serving as the boundary lines exist in the fillet surfaces F1 and F2, the mesh M or the like of the standard size When the fillet surfaces F1 and F2 can be properly divided, unnecessary data erasure can be prevented by leaving the shape lines L2 and L3.

  In particular, as shown in the above embodiment, the arc lengths A1 and A2 of the first and second fillets F1a, F1b, F2a, and F2b, which are the criteria for determining whether or not to delete the boundary line data by the boundary line erasing means 9, are shown. When A2, B1, and B2 are set to values corresponding to the standard size of the mesh designated by the input means including the keyboard 3 and the mouse 4, the arc lengths A1, A2, B1, and B2 are By determining whether or not the value is smaller than the reference value set to the value corresponding to the standard size of the mesh created by the mesh creating means 12, it is possible to prevent the deletion of the shape line data that does not need to be erased. However, there is an advantage that a structural analysis model in which the fillet surfaces F1 and F2 are divided by a standard size mesh can be automatically and appropriately created.

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 other example of the shape line read from CAD data. It is a flowchart which shows an example of the control action which produces a structural analysis model. It is explanatory drawing which shows the specific example of a structural analysis model. It is explanatory drawing which shows the other specific example of a structural analysis model.

Explanation of symbols

8 CAD data storage means 9 Fillet surface detection means 10 Boundary line deletion 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 a pair of fillets are paralleled based on the CAD data. The fillet surface detecting means for detecting the arranged fillet surface, the boundary line erasing means for detecting the boundary line of the fillet existing in the fillet surface and erasing the data, and the boundary line in the fillet surface are deleted. Shape line data storage means for storing the data of the shape line left by the process, and mesh data creation means for creating mesh data of the fillet surface based on the data of the shape line stored in the shape line data storage means; A vehicle body panel structural analysis model creation system characterized by comprising:   The boundary line erasing means determines whether the arc length of the fillet constituting the fillet surface is less than a preset reference value, and if it is confirmed that the fillet surface is less than the reference value, 2. The structural analysis model creation system for a vehicle body panel according to claim 1, wherein a boundary line of a fillet existing in the vehicle is detected and the data is erased.   The arc length of the fillet that is a criterion for determining whether or not to delete the boundary line data by the boundary line deleting unit is set to a value corresponding to the standard size of the mesh created by the mesh data creating unit. The structural analysis model creation system for a vehicle body panel according to claim 2, wherein the system is a structural analysis model creation system.

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