JP2008033727A - Numerical analysis data production device, numerical analysis data production method and program for making computer execute the production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform grouping according to a shape of a bolt hole by use of CAD data, and to stick a vertical shell onto a bolt seat surface, so as to produce mesh data allowing high-accuracy numerical analysis. <P>SOLUTION: This numerical analysis data production device includes a CAD (Computer aided Design) database 1000, a face processing and grouping processing part 2000 of a rigid body sticking range, an FEM (Finite Element Method) mesh production part 3000, an FEM shape and FEM virtual database 4000, grouping information database 5000, a rigid body data production part 6000, and an FEM shape and rigid body database 7000. In the numerical analysis data production device, a range including the bolt seat surface attached with a bolt that is a rigid body is set, the same bolt holes are executed with grouping processing to the same group, a rigid body principal point is produced in gravity center coordinates of a virtual shell element of each the group, and a rigid body element is produced with the rigid body principal point and a contact point configuring a shell element of each group as dependent points. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for creating mesh data applied to a numerical analysis method such as a finite element method (hereinafter sometimes referred to as FEM (Finite Element Method)), and in particular, has a hole such as a bolt hole. The present invention relates to a member mesh creation technique.

  In machine design, a CAD (Computer Aided Design) system is used to improve design efficiency. In a design process for a machine product designed using such a CAD system, shape information such as a shape model and an assembly and attribute information accompanying shape information necessary for design and production are integrated. It is necessary to handle without contradiction. For this reason, for example, grouping is performed for each machine product having the same shape.

  For example, Japanese Patent Laid-Open No. 2001-142517 (Patent Document 1) discloses a molding shape recognition method that automatically recognizes a molding shape portion of a three-dimensional sheet metal model from the shape and adds attribute information for processing. This forming shape recognition method is a sheet metal which is a three-dimensional model of a product created by three-dimensional CAD by converting data related to a plurality of types of three-dimensional CAD models and restoring them to a specific three-dimensional CAD. A method of recognizing a forming shape that is a shape of a forming part existing in a model and adding attribute information, and in order to perform processing for recognizing a forming shape existing in a sheet metal model, this sheet metal model is In the sheet metal model import step, the basic attribute data is added to the sheet metal model. Additional steps, molding shape surface group that is a collection of surfaces of each molding shape existing in the sheet metal model, sheet thickness surface group that is a collection of sheet thickness surfaces, and surface of the sheet metal model A sheet metal shape recognition step for recognizing a surface group and a development target surface group consisting of a back surface group that is a back surface of the sheet metal model, and a continuous surface of the plate thickness surface group, the development target surface group, and the molding shape surface group. Joining together, surface thickness step to generate plate thickness shape, development target surface shape, and molding shape, and grouping by classifying the molding shape of the same shape out of multiple types of molding shapes Mold shape identification step that identifies the type of molding that exists in the product from the molding shape classification step, geometric shape, material, and plate thickness of the molded shape, generates attribute information corresponding to this molding type, and temporarily stores it A step and an attribute information adding step of adding attribute information temporarily stored to an element related to the sheet metal model so that NC data for processing the product can be created.

  According to the molding shape recognition method of this sheet metal model, the three-dimensional sheet metal model is read in units of planes, classified into a sheet thickness surface group, a development target surface group, and a molding surface group, and the surfaces are joined for each surface type. . Then, the attribute information is added to the position where the molding shape exists while grouping for each molding shape and referring to the learning shape registered in the learning database. On the other hand, the sheet metal model is developed, and the attribute information added to the model is inherited to the developed shape. NC data is generated by assigning a mold for processing the product to the developed shape. Then, the NC data is transmitted to the NC processing machine to process the product. Since the processing is performed in this manner, for example, since the molding specification processing is performed from the molded shape, there is an effect that the design side can create a model without hindering a three-dimensional merit (for example, interference check of the molded shape). .

In addition to this Patent Document 1, in such CAD and FEM, techniques related to these are disclosed in the following publications.
JP 2001-142517 A JP-A-8-30663 JP 2002-219523 A Japanese Patent Laid-Open No. 11-102383 JP 2005-138120 A

  For example, there may be provided a large number of holes for fastening each other with a large number of bolts, such as an engine cylinder head or a cylinder block. Since the hole portion of such a member is a space, it cannot be handled as a rigid body. For this reason, an FEM mesh cannot be accurately created for the hole and its periphery. In particular, it is difficult to accurately analyze what kind of stress is generated in the portion where the bolt seat surface around the hole is in contact.

  However, none of the above-mentioned patent documents grasps such a problem, and therefore cannot solve such a problem.

  Furthermore, since the CAD data contains more information than the data necessary for FEM, it is difficult to easily process CAD data into FEM shape data. For this reason, it is conceivable to manually create a mesh around the hole, but even if a large number of bolts are used, such as the joining of the cylinder head and the cylinder block, one by one. It is not realistic from the viewpoint of man-hours to manually create the bolt holes and surrounding meshes.

  The present invention has been made in order to solve the above-described problems, and an object thereof is, for example, numerical analysis (represented by FEM) based on CAD data for a machine product having a large number of holes having the same shape. It is to provide a numerical analysis data creation apparatus, a numerical analysis data creation method, and a program for causing a computer to realize the creation method.

  A numerical analysis data creation device according to a first aspect of the present invention is a numerical analysis data creation device used in a numerical analysis method for analyzing physical characteristics of a member configured by being fastened by a plurality of fastening members. A plurality of holes corresponding to the plurality of fastening members are provided on the surface of the member. This numerical analysis data creation device is configured to read a plurality of partial surfaces including holes in an analysis surface that is a target of a numerical analysis method based on reading means for reading three-dimensional mechanical design data and three-dimensional mechanical design data. , Group setting means for setting as the same group if the predetermined factors are common, mesh creation means for creating a mesh on the analysis surface based on the three-dimensional mechanical design data, set groups and creation And a numerical analysis method for setting a rigid element and a rigid principal point for a partial surface where the fastening member abuts on the surface of the member by attaching a virtual shell element to the hole based on the mesh Output means for outputting data corresponding to the surface mesh and data about the rigid body. Moreover, the numerical analysis data creation method according to the fourth invention has a configuration corresponding to the first invention.

  According to the first or fourth invention, a member having a hole (bolt hole) into which a fastening member such as a bolt is inserted is numerically analyzed (FEM or the like) based on three-dimensional mechanical design data (CAD data). In addition to surface processing (surface processing) of the analysis surface, for example, bolt holes on the same surface fastened with the same bolt are set as the same group. A virtual shell element is attached to the bolt hole portion to set a rigid body element and a rigid body principal point. By doing so, it is possible to automatically create FEM meshes in groups from CAD data on the bolt seat surface around the bolt hole portion on the analysis surface by computer processing. As a result, for example, a numerical analysis data creation apparatus and a numerical analysis data creation method that can easily create mesh data for numerical analysis (represented by FEM) based on CAD data for a large number of mechanical products having holes of the same shape. Can be provided.

  In the numerical analysis data creation device according to the second invention, in addition to the configuration of the first invention, the fastening member is a bolt, and the partial surface is a seat surface of the bolt. The setting means attaches the virtual shell element to the surface including the hole and the seating surface, sets the barycentric coordinates of the virtual shell element as a rigid principal point, and sets the contact points constituting the virtual shell element as a dependent point. Means for setting a rigid body composed of rigid principal points and dependent points as rigid body elements. The numerical analysis data creation method according to the fifth invention has a configuration corresponding to the second invention.

  According to the second or fifth invention, a virtual shell element can be attached to the bolt hole portion, and the rigid body principal point can be calculated as the center of gravity coordinates of the virtual shell element and set as the rigid body principal point. . Further, the rigid body element can be calculated by calculation as being composed of the rigid principal point and the dependent point (contact point constituting the virtual shell element), and can be set as the rigid element.

  In the numerical analysis data creation device according to the third invention, in addition to the configuration of the first or second invention, the factor is at least one of a material characteristic, a shape characteristic of the fastening member, and a mounting surface of the fastening member. . The numerical analysis data creation method according to the sixth invention has a configuration corresponding to the third invention.

  According to the third or sixth invention, since grouping factors can be set to various factors to perform grouping, even if there are many bolt holes, the group can be set flexibly, with a small number of groups. Many bolt holes can be processed.

  A program according to a seventh aspect is a program that causes a computer to execute any one of the fourth to sixth numerical analysis data creation methods.

  According to the seventh invention, the same effect as any one of the fourth to sixth inventions can be expressed using a computer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, a control block diagram of the numerical analysis data creation device according to the present embodiment will be described.

  As shown in FIG. 1, a numerical analysis data creation device according to the present embodiment includes a CAD database 1000, a rigid body pasting range surface processing and grouping processing unit 2000, an FEM mesh creation unit (virtual shell element) 3000, FEM shape and FEM virtual database 4000, grouping information database 5000 connected to surface processing and grouping processing unit 2000 of the rigid body pasting range, and rigid body data generation connected to FEM shape and FEM virtual database 4000 and grouping information database 5000 The unit 6000 is connected to the rigid body data creation unit 6000, and includes an FEM shape and a rigid body database 7000 that outputs data of rigid body principal points and rigid body elements. A numerical analysis method such as a finite element method is executed using the data of the FEM shape and the rigid body database 7000.

  The rigid body data creation unit 6000 includes a rigid body principal point arrangement processing unit 6100 and a rigid body element creation processing unit 6200.

  The FEM mesh creation unit (virtual shell element) 3000 creates FEM shape data and creates virtual shell elements on the grouped analysis surfaces. For example, the material characteristic number is the surface number, and the grouping range can be identified.

  The grouping information database 5000 is a database of number information of grouped surfaces (surfaces). The rigid principal point arrangement processing unit 6100 creates a rigid principal point based on the barycentric coordinates of the processing elements for each group (material characteristic number). The rigid element creation processing unit 6200 creates a rigid element using the rigid principal points created by the rigid principal point arrangement processing unit 6100 and the contact points constituting the virtual shell elements for each group (material property number) as subordinate points. To do.

  A specific example of mesh data stored in the CAD database 1000 will be described. The mesh data represents a contact number N which is a number for identifying a contact, a contact coordinate X (x, y, z) based on a specific coordinate system, and a contact number string of a contact point to which the contact is connected. The contact information group written in association with the connection information M is formed. One piece of contact information is expressed as N (X, M). In addition, information such as a physical constant of a rigid body such as density, Young's modulus, Poisson's ratio, and a coordinate transformation matrix between coordinate systems is written at the beginning of the mesh data.

  Note that the representation of the contact information shown here is an example, and the numerical analysis data creation device according to the present embodiment is not limited to such data.

  Moreover, in the following description, since the mesh creation method and the like can be executed with reference to existing technology (for example, the above-described patent document), detailed description will not be repeated in this specification.

  A control structure of a program executed by the numerical analysis data generation device according to the present embodiment will be described with reference to the flowchart of FIG.

  In step (hereinafter, “step” is described as S) 100, the numerical analysis data creation apparatus reads CAD data from the CAD database 1000.

  In S110, the numerical analysis data creation device executes surface machining within a range in which a rigid body (bolt) is attached. At this time, the surface processing of the rigid body attachment range is performed by the surface processing and grouping processing unit 2000 of the rigid body pasting range.

  In S120, the numerical analysis data creation device executes grouping of rigid body (bolt) attachment ranges. At this time, the surface processing and grouping processing unit 2000 of the rigid body pasting range executes the grouping processing of the rigid body mounting range.

  In S 130, the numerical analysis data creation device stores the grouped surface (surface) information in grouping information database 5000.

In S140, the numerical analysis data creation device creates an FEM mesh.
In S150, the numerical analysis data creation device creates a virtual shell element in the grouped attachment range. At this time, the FEM mesh creation unit (virtual shell element) 3000 executes a process of attaching the virtual shell element to the grouped attachment range.

  In S160, the numerical analysis data creation device calculates the center-of-gravity coordinates of the virtual shell element, and creates a rigid principal point at the center-of-gravity coordinates. That is, the barycentric coordinate of the virtual shell element is set as the rigid principal point.

  In S170, the numerical analysis data creation device creates a rigid body element as a rigid body principal point and a dependent point (a contact point constituting an element for each group (material characteristic number)).

  The processing in S160 and S170 is executed by the rigid body principal point arrangement processing unit 6100 and the rigid element creation processing unit 6200 of the rigid body data creation unit 6000.

  The operation of the numerical analysis data creation device according to the present embodiment based on the above-described structure and flowchart will be described.

  The numerical analysis data creation apparatus is actually realized by software executed on a computer such as a personal computer or a workstation. That is, an apparatus for creating data for performing numerical analysis by the boundary element method or the finite element method is realized by computer hardware and software executed by a CPU (Central Processing Unit). Generally, such software is stored and distributed on a recording medium such as a flexible disk, CD-ROM, or DVD-ROM, and is read from the recording medium by a reading device provided in a computer or received via a communication line. Is temporarily stored in the fixed disk. Further, the program is read from the fixed disk to the memory and the program is executed by the CPU. Therefore, an essential part of the present invention is software received by a computer via a recording medium or a communication line.

  FIG. 3 illustrates the operation of the numerical analysis data creating apparatus according to the present embodiment, taking a member having a bolt hole as a simplified numerical analysis target as an example.

  Here, the purpose of the work content is to create a rigid element on the bearing surface of the bolt for coupling with other parts using CAD data.

  CAD data requiring a bolt hole as shown in the uppermost part of FIG. 3 is read (S100), and the dependent range of the rigid body is processed into a CAD meter shape. That is, as described in the second stage of FIG. 3, CAD surface processing is performed as a bolt seat surface. A surface number grouped with respect to the bolt seating surface is set. Here, the surface numbers of the bolt bearing surfaces are set as the same group for the three bolt holes. Data obtained by machining the bolt bearing surface is output to the grouping information database 5000 (S130).

  An FEM shape mesh is created (S140), and a virtual shell element is created on the grouping surface (S150). At this time, as shown in the second row from the bottom in FIG. 3, for example, a shell element created at the surface number 1111 is created as data of PSHELL 1111.

  The barycentric coordinates of the virtual shell element are calculated, and a rigid principal point is created at the barycentric coordinates (S160). A rigid element composed of a rigid principal point and a dependent point is created (S170). The shell created on the surface 1111 and the principal points and dependent points are shown at the bottom of FIG.

  Furthermore, the operation of the numerical analysis data creation device according to the present embodiment will be described with reference to data that is closer to reality.

  FIG. 4 shows a plan view of an engine cylinder block represented by CAD data. FIG. 5 shows a diagram representing the FEM mesh corresponding to FIG. FIG. 6 shows a diagram obtained by adding a rigid principal point to FIG.

  As shown in FIG. 4, the cylinder block drawn by CAD data has six bolt holes 8010 having the same shape on the surface of the cylinder block 8000 (one group in this) and bolt holes having different bolt hole shapes. There are two 8020s (this is one group).

  FIG. 5 shows a case where an FEM mesh is created for the cylinder block 8000 shown in FIG. An enlarged view of the bolt hole 8010 at the upper left end is also shown in FIG.

  The hatched portion in the enlarged view corresponds to the bolt seat surface. Further, as shown in FIG. 6, a virtual shell is attached to the bolt hole including the bolt seat surface, and the center of gravity of the virtual shell data is measured and set as the rigid main point 8030. Instead of setting the barycentric coordinates of the virtual shell data as the rigid principal point, the average value of the constituent contact coordinates of the virtual shell data may be set as the rigid principal point.

  In addition, when it is desired to connect a plurality of bolt seats with one rigid body, a flying ground is created as shown in FIG. The flying ground is recognized as a single surface (given the same surface number) with the point represented by the point 9000 as the center of the rigid body.

  As described above, according to the numerical analysis data creation device according to the present embodiment, the virtual shell data is pasted on the bolt seat surface in the member having a large number of bolt holes using the three-dimensional CAD data, and the same bolt By setting the holes as the same group, the rigid element and the rigid principal point can be easily set on the bolt bearing surface. It is possible to analyze what kind of stress is generated on the bolt bearing surface by numerical analysis such as a finite element method using the rigid body principal point and the rigid body element set as described above. As a result, mesh data for FEM can be easily created using CAD data having a large amount of information and a large amount of data.

  In addition, it is possible to automatically set the rigid principal points and rigid elements on the bolt seat surface much faster than when manually setting rigid elements and rigid principal points for a large number of bolt holes as in the past. Become so.

  Note that the grouping may be based on the characteristics of the mounting surface, or may be divided by surface, radius, corner, or the like. Furthermore, it is possible to create and add elements other than rigid bodies (such as beams, springs, masses, fixed IDs, etc.) by naming and distinguishing group names and by targeting not only faces but also curves. Become.

  For example, an example of such grouping is a beam 10040 set in the bolt hole 10030 shown in FIG. In FIG. 8, a bolt seating surface 10000, a member 10020 to be analyzed, and a contact 10050 are shown.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram of the numerical analysis data creation apparatus which concerns on embodiment of this invention. It is a flowchart which shows the control structure of the program performed with the numerical analysis data creation apparatus which concerns on embodiment of this invention. It is a figure which shows the state of the data processed with the numerical analysis data creation apparatus which concerns on embodiment of this invention. It is a top view of the cylinder block of the engine represented by the data for CAD. It is a figure showing the FEM mesh corresponding to FIG. It is the figure which added the rigid principal point to FIG. It is the figure which added the jumping point to FIG. It is a figure for demonstrating an example of grouping.

Explanation of symbols

  1000 CAD database, 2000 rigid body pasting range surface processing and grouping processing unit, 3000 FEM mesh creation unit (virtual shell element), 4000 FEM shape and virtual FEM database, 5000 grouping information database, 6000 rigid body data creation unit, 7000 FEM shape and Rigid body database.

Claims (7)

A numerical analysis data creation device used in a numerical analysis method for analyzing physical characteristics of a member configured by being fastened by a plurality of fastening members, wherein a plurality of holes corresponding to the plurality of fastening members are formed on a surface of the member Part is provided,
The numerical analysis data creation device includes:
Reading means for reading 3D machine design data;
Group setting for setting a plurality of partial surfaces including the hole portion as the same group when a predetermined factor is common in the analysis surface that is a target of the numerical analysis method based on the three-dimensional mechanical design data Means,
Based on the three-dimensional mechanical design data, a mesh creation means for creating a mesh on the analysis surface;
Based on the set group and the created mesh, a virtual shell element is affixed to the hole, and a rigid element and a rigid principal point for a partial surface where the fastening member abuts on the surface of the member. A setting means for setting;
A numerical analysis data creation device including output means for outputting data corresponding to the surface mesh and data on the rigid body so that the numerical analysis method can be executed. The fastening member is a bolt,
The partial surface is a seating surface of the bolt,
The setting means affixes a virtual shell element to a surface including the hole and the seating surface, sets the center-of-gravity coordinates of the virtual shell element as the rigid principal point, and sets contact points constituting the virtual shell element. The numerical analysis data creation device according to claim 1, comprising means for setting as a dependent point and setting a rigid body constituted by the rigid principal point and the dependent point as the rigid element.   The numerical analysis data creation device according to claim 1, wherein the factor is at least one of a material characteristic, a shape characteristic of the fastening member, and a mounting surface of the fastening member. A numerical analysis data creation method for use in a numerical analysis method for analyzing physical characteristics of a member constituted by being fastened by a plurality of fastening members, wherein a plurality of holes corresponding to the plurality of fastening members are formed on the surface of the member Part is provided,
The numerical analysis data creation method is:
A reading step for reading 3D machine design data;
A group setting step for setting a plurality of partial surfaces including the hole in the analysis surface that is a target of the numerical analysis method as the same group based on the three-dimensional mechanical design data if a predetermined factor is common; and ,
A mesh creating step of creating a mesh on the analysis surface based on the three-dimensional mechanical design data;
Based on the set group and the created mesh, a virtual shell element is affixed to the hole, and a rigid element and a rigid principal point for a partial surface where the fastening member abuts on the surface of the member. A setting step to set;
A numerical analysis data creation method including an output step of outputting data corresponding to the surface mesh and data on the rigid body so that the numerical analysis method can be executed. The fastening member is a bolt,
The partial surface is a seating surface of the bolt,
In the setting step, a virtual shell element is affixed to a surface including the hole and the seating surface, a barycentric coordinate of the virtual shell element is set as the rigid principal point, and a contact point constituting the virtual shell element is set. The numerical analysis data generation method according to claim 4, further comprising a step of setting as a dependent point and setting a rigid body composed of the rigid body principal point and the dependent point as the rigid body element.   The numerical analysis data creation method according to claim 4, wherein the factor is at least one of a material characteristic, a shape characteristic of the fastening member, and an attachment surface of the fastening member.   A program for causing a computer to execute the numerical analysis data creation method according to any one of claims 4 to 6.

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