JP2016164762A - Analysis model creation device, analysis model creation program and analysis model creation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the time for creating an analysis model and improve the precision of analysis.SOLUTION: An analysis model creation device of an embodiment comprises the following functions. The entire region corresponding to the shape of an analysis object is divided into first divided elements having the mutually regular shape. The edge part of the entire region is divided into second divided elements having the arbitrarily determined shape. A database including information which shows positions of nodes of the first and second divided elements is created. With reference to the database, on the basis of a relative positional relation between nodes of the respective first and second divided elements having an overlap region, information on deviation of nodes at the time when stress is applied to the analysis object is set. With reference to the database, on the basis of the degree of overlap of the first and second divided elements, information on rigidity to the divided elements having an overlap region is set. An analysis model is created by employing the information on deviation and rigidity.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an analysis model creation device, an analysis model creation program, and an analysis model creation method.

  Structural analysis using an analysis model is useful for evaluating the soundness and strength of a structure. Large-scale analysis that obtains results by directly modeling complex shapes as an analysis model has been actively incorporated into product design and development due to recent improvements in computer performance and development of analysis technology.

  However, large-scale analysis requires enormous time and labor to create an analysis model. In particular, in the structural analysis and fluid analysis of complicated shapes, the time required to create an analysis model may be longer than the analysis time. That is, the analysis model creation time is an important item for shortening the lead time for product development and design.

  Usually, when modeling an analysis of a three-dimensional shape, the analysis space inside the analysis object of the three-dimensional shape is divided into elements using the three-dimensional CAD data. The analysis model obtained through the element division or the like is subjected to numerical analysis after boundary conditions and the like are set, and an analysis result is output. Here, enormous time and labor for creating the analysis model are often required when the analysis space is divided into elements. For example, if an element having a distorted shape is used for element division, the analysis accuracy is greatly reduced. In such a case, the element division is performed manually by a technician having expertise.

  In view of the above problems, an auto mesh technique for automatically dividing an element has been developed. For example, an ultra-high-speed mesh generator that implements auto-mesh technology in software can significantly reduce the work time for element division and reduce the work time to, for example, 1/3 to 1/20 or less of the conventional method. Is possible.

  Voxel element technology, which is a kind of auto mesh technology, is also used. The voxel element technology can create an analysis model in a short time by using regular lattice units (voxels) having a regular shape in a three-dimensional space. For example, the shape data defining the surface shape of the analysis object is divided into voxel elements and converted into an analysis model.

  Analytical modeling with voxel elements uses limited-shaped elements, so the element formation time is overwhelmingly short compared to analytical modeling with arbitrary-shaped elements, and analysis accuracy is easily secured and managed. . On the other hand, the edge (surface) of the analysis model is disadvantageous, for example, because it is difficult to align the curved surface of an arbitrary shape and the boundary of the voxel element, which may cause a boundary condition setting error and a decrease in analysis accuracy. There is. In particular, in the field of structural analysis, the frequency of evaluating stress values at the edges of structures where stress concentration is likely to occur is high. Therefore, a decrease in analysis accuracy at the edge of the analysis model can be said to be a major drawback when the voxel element technology is used.

  In order to avoid such defects, the shape of each voxel element is automatically corrected by detecting the separation between the ideal shape of the edge of the analysis object and the shape of the voxel element located at the edge of the analysis model. Techniques to do this have been proposed. However, this technique makes it difficult to ensure and manage the analysis accuracy because the voxel element is locally distorted at the edge of the analysis model.

  Therefore, apart from the voxel element, another element approximated to the ideal shape of the edge of the analysis object is arranged for the edge of the analysis model where the analysis accuracy is likely to be reduced. A technique for improving analysis accuracy by solving voxel elements by a finite covering method is also known. However, this technique is more difficult to apply to large-scale analysis because the load of convergence calculation (iteration calculation) is larger than the conventional general finite element method, and the analysis time is inevitably longer. It has been demanded.

JP 2000-182081 A Japanese Unexamined Patent Publication No. 2000-194881 Japanese Patent No. 3272830 Mamoru Tanaka et al., “Manufacturing Innovation Utilizing Numerical Simulation to Improve Productivity”, Mitsubishi Heavy Industries Technical Review, Vol.48, No.1, pp.61-64 (2011). Toshifumi Shimamura et al., “Analysis by Finite Cover Method and Superposition Mesh Method”, Proceedings of the Lecture on Computational Engineering, Vol.10, pp375-376 (2005). Suzuki Katsuyuki et al., “Improvement of accuracy of finite covering method in superposition mesh method”, Proceedings of the 18th Japan Society of Mechanical Engineers, pp.177-178 (2005).

  As described above, for example, in large-scale structural analysis used to evaluate the soundness and strength of structures, the creation time of analysis models is short, the analysis accuracy is high, and the calculation time is short. An analysis method that combines In particular, there is a demand to establish an analysis method that can shorten the creation time of the analysis model and obtain excellent analysis accuracy and analysis convergence by using the voxel element technology.

  Accordingly, the problem to be solved by the present invention is to provide an analysis model creation device, an analysis model creation program, and an analysis model creation method that can shorten the creation time of an analysis model and increase the analysis accuracy.

  The analysis model creation apparatus according to the embodiment includes a first division processing unit, a second division processing unit, a database generation unit, a displacement information setting unit, a stiffness information setting unit, and an analysis model creation processing unit. The first division processing unit divides the entire region corresponding to the shape of the analysis object into a plurality of first division elements having a regular shape. A 2nd division | segmentation process part divides | segments the edge part of the whole area | region corresponding to the shape of the said analysis target object into several 2nd division elements which have the shape defined arbitrarily. The database generation unit generates a database having information indicating the positions of at least nodes of the plurality of divided first and second divided elements. The displacement information setting unit obtains the relative positional relationship between the nodes of the first and second divided elements having overlapping regions while referring to the generated database, and the obtained relative position. Based on the relationship, information on the displacement of the mutual nodes when stress is applied to the analysis object is set. The stiffness information setting unit obtains the degree of duplication between the first and second division elements having the overlapping area while referring to the generated database, and based on the obtained degree of duplication, Information on rigidity is set for the divided element having the region. The analysis model creation processing unit creates the analysis model by taking in the information on the set displacement and the information on the rigidity.

1 is a block diagram showing a configuration of a structural analysis system including an analysis model creation device according to a first embodiment. The process flow figure by the structural analysis system of FIG. The figure which shows an example of the CAD data which the analysis model creation apparatus of FIG. 1 acquires. The model figure of the internal element obtained based on the CAD data of FIG. The model figure of the surface element obtained based on the CAD data of FIG. FIG. 6 is a model diagram showing the internal elements of FIG. 4 and the surface elements of FIG. The schematic diagram for demonstrating the internal element inclusion calculation of the surface element by the analysis model creation apparatus of FIG. The other schematic diagram for demonstrating the internal element inclusion calculation of FIG. The figure which shows the local coordinate system used by the calculation 4 by the analysis model creation apparatus of FIG. The schematic diagram which illustrated the detection of the intersection in the calculation 5 by the analysis model creation apparatus of FIG. The schematic diagram which shows the surface element overlapping surface of the internal element in the calculation 5 of FIG. The schematic diagram showing the concept of the projection area ratio by the calculation 5 of FIG.10 and FIG.11. The contour figure which shows the analysis result by the structure analysis system of FIG. The contour figure which shows the analysis result by the structural analysis method of a comparative example. The figure showing the precision of the analysis result by the structure analysis system of FIG. The block diagram which shows the structure of the structural analysis system containing the analysis model production apparatus which concerns on 2nd Embodiment. The process flow figure by the structure analysis system of FIG. The schematic diagram for demonstrating the creation process of the surface element by the analysis model creation apparatus of FIG. The schematic diagram for demonstrating the creation process following FIG. 18A. The schematic diagram for demonstrating the creation process following FIG. 18B. The block diagram which shows the structure of the structural analysis system containing the analysis model production apparatus which concerns on 3rd Embodiment. The process flow figure by the structural analysis system of FIG. The schematic diagram for demonstrating the creation process of the surface element by the analysis model creation apparatus of FIG. The schematic diagram for demonstrating the creation process following FIG. 21A. The schematic diagram for demonstrating the creation process following FIG. 21B.

Hereinafter, embodiments will be described with reference to the drawings.
<First Embodiment>
As shown in FIG. 1, the structural analysis system 30 according to the present embodiment includes an analytical model creation device 20, a structural analysis processing unit 27, and an analysis result output unit 28. As shown in FIG. 1, the analysis model creation apparatus 20 includes a CAD (Computer Aided Design) data acquisition unit 26, a first division processing unit 21, a second division processing unit 22, a database generation unit 29, a displacement information setting unit 23, A stiffness information setting unit 24 and an analysis model creation processing unit 25 are provided.

  Here, the analysis model creation device 20 is equipped with various types of hardware such as a main memory such as a RAM, an auxiliary (secondary) storage device such as an HDD, a CPU, and a ROM. The analysis model creation device 20 loads an analysis model creation program stored in advance in an auxiliary (secondary) storage device such as a hard disk or a ROM onto the main memory, whereby the first division processing unit 21 and the second division processing are performed. The above-described components including the unit 22, the database generation unit 29, the displacement information setting unit 23, and the like are realized by software, for example. Note that these components may be configured by hardware instead of software.

  Here, FIG. 2 is a process flow diagram by the structure analysis system 30 of FIG. 1, and FIG. 3 is a diagram showing an example of CAD data 31 acquired by the analysis model creation apparatus 20 of FIG. 4 is a diagram showing an internal element model 32 obtained based on the CAD data 31 of FIG. 3, and FIG. 5 shows a surface element obtained based on the CAD data 31 of FIG. It is a figure which shows the model 33. FIG. Further, FIG. 6 is a model diagram showing the internal elements and surface elements of FIG. As shown in FIG. 3 to FIG. 6, the evaluation site evaluated by the structural analysis by the structural analysis system 30 is an edge of the analysis object, and more specifically, for example, a concave portion (curved portion) where stress concentration may occur. ).

  As shown in FIG. 2, the structural analysis system 30 according to the present embodiment has basic physical properties for inputting CAD data as an input item 1 and an elastic modulus (such as Young's modulus) of a material to be analyzed as an input item 2. By inputting four input items such as value input, internal element shape designation as input item 3, and surface element shape designation as input item 4, an analysis input file (analysis model) is output by automatic calculation.

  Further, as shown in FIG. 2, the structural analysis system 30 includes an internal element group creation process as operation 1, a surface element group creation process as operation 2, a surface element inclusion operation as operation 3, and an internal / Five calculations are performed: a surface element nodal displacement transmission amount calculation and a calculation 5 (overlapping part) internal element stiffness calculation.

  Specifically, as shown in FIGS. 1 to 3, the CAD data acquisition unit 26 acquires CAD data 31. As shown in FIG. 3, the CAD data includes a plurality of coordinate data and shape surface data (curved surface data) representing the shape of the surface including these coordinate data. The CAD data acquisition unit 26 obtains an area (coordinate space) corresponding to the shape of the analysis object from these data.

  As shown in FIGS. 1, 2, 4, and 6, the first division processing unit 21 has a total area corresponding to the shape of the analysis target based on the shape of the designated internal element (element size of the internal element). Are divided into a plurality (finite number) of internal elements (first division elements) 1 having a regular shape (a shape designated by the input item 3). That is, as shown in FIG. 4, the first division processing unit 21 performs element division by applying a hexahedral element, which is a regular lattice unit having a uniform shape and size, as the internal element 1.

  Since the first division processing unit 21 applies the internal elements 1 having regular shapes and sizes to perform modeling including element division, the first division processing unit 21 can perform automatic processing using existing software or the like, and is extremely short. Processing is completed in time. The modeling including such element division by the first division processing unit 21 includes a process of setting an initial value of the elastic modulus for each divided internal element 1 (input process in the input item 2). .

  As shown in FIGS. 1, 2, 5, and 6, the second division processing unit 22 arbitrarily determines the edge of the entire region corresponding to the shape of the analysis target (input item 4 It is divided into a plurality (finite number) of surface elements (second division elements) 5 having a shape. That is, as shown in FIGS. 5 and 6, the second division processing unit 22 performs modeling smoothly using the plurality of surface elements 2 along the surface shape of the analysis object.

  Specifically, the second division processing unit 22 has a range specified by an input operation to the main body of the analysis model creation apparatus 20 at the edge of the entire region corresponding to the shape of the object to be analyzed (the depression to be an evaluation part). The curved portion is divided into a plurality of surface elements 2. The position where the surface element 2 is arranged can be arbitrarily designated by the analyst himself such as a place where analysis accuracy is required or a place where boundary conditions are required.

  As shown in FIGS. 5 and 6, a hexahedral element is used for the surface element 2. It is also possible to apply a shell element having a shape restriction to the surface element 2. Here, each process by the first division processing unit 21 and the second division processing unit 22 is based on the acquired CAD data to create a shell element or a solid element with a thickness, such as a pre-post processor. Do through. Thereby, it becomes possible to specify an evaluation part arbitrarily and to model quickly.

  As shown in FIGS. 1 and 2, the database generation unit 29 generates, for example, a database (DB) having information indicating the positions of at least nodes of a plurality of divided internal elements and surface elements. More specifically, the database generation unit 29 constructs the following nine databases (DB1 to DB9). As shown in FIG. 2, the DB 1 stores CAD data such as a model shape. The DB 2 is a database that stores an element number (internal element identification number) for specifying (identifying) an internal element in association with a physical property value such as Young's modulus. The DB 3 is a database that stores an internal element node number that is a node number for each internal element and its coordinates (coordinate values) in association with each other. The DB 4 is a database that stores an internal element number that identifies each internal element and an internal element node number in association with each other.

  The DB 5 is a database that stores node numbers for each surface element and their coordinates (coordinate values) in association with each other. The DB 6 is a database that stores a surface element number for specifying (identifying) individual surface elements and a surface element node number in association with each other. The DB 7 is a database that stores surface element node numbers and internal element numbers in association with each other. The DB 8 is a database that stores transmission nodes and transmission amounts in association with each other. The DB 9 is a database that stores a surface element number and an elastic modulus (longitudinal elastic modulus [Young's modulus], etc.) in association with each other.

  The displacement information setting unit 23, the rigidity information setting unit 24, and the analysis model creation processing unit 25 execute a connection process for connecting the internal element and the surface element described above. This connection process is a process of automatically correcting so that an appropriate value can be obtained even if the analysis result is obtained while the internal element and the surface element overlap.

  Here, as shown in FIGS. 1 and 6, the displacement information setting unit 23 connects nodes of the internal element and the surface element so that mutual displacement can be transmitted. That is, the displacement information setting unit 23 refers to the database generated by the database generation unit 29, and obtains the relative positional relationship between the nodes of the internal element and the surface element having overlapping regions, Based on the relative positional relationship, information on the displacement of the nodes when the stress is applied to the analysis object is set.

  On the other hand, the stiffness information setting unit 24 sets material characteristics and the like in consideration of an overlapping portion (overlapping portion) where the internal element and the surface element overlap, and the deformation amount of the overlapping portion affects the influence of the overlapping of the elements. Make sure that the value is appropriate. That is, the stiffness information setting unit 24 refers to the database generated by the database generation unit 29, obtains the degree of overlap between the internal elements and the surface elements having overlapping regions, and based on the obtained degree of overlap. Then, information on rigidity is set for the divided element having the overlapping region.

  Furthermore, the structure of the structural analysis system 30 provided with the analysis model creation apparatus 20 of the present embodiment will be described in more detail. As described above, the analysis model to be created in the present embodiment is an analysis model in which the surface element 2 and the internal element 1 are partially overlapped (overlapped) as shown in FIG.

  Therefore, the analysis model creation apparatus 20 uses the input items 1, 3 and 4 described above to use the internal element and surface element nodes defined by automatic calculation, and the element dimensions of the internal elements and surface elements, to obtain the surface element nodes. Detecting the internal elements that contain the element, and using the internal nodes defined from the calculation results as a database, the displacement transmission amount setting calculation, which is the calculation for connecting the surface element and the internal element, and reducing the overlap error The stiffness correction calculation is automatically performed.

  That is, the database generated by the database generation unit 29 includes a database that stores information that identifies an internal element that includes a node of a surface element among a plurality of internal elements divided by the first division processing unit 21. It is out. With this configuration, an analysis model with excellent analysis accuracy can be created in a short time.

  Here, as described above, in the input item 4, the analyst himself / herself arbitrarily determines a part that requires more accurate analysis accuracy and designates a surface element. As shown in FIG. 2, the surface element can be specified through the CAD data in the input item 1, and by inputting the specified part (specified position), the thickness of the surface element, and the number of element divisions, Created by mesh creation technology. The surface element is generated so as to be extruded from the shape surface of the CAD data into the structure. Here, in the present embodiment, the thickness of the surface element and the element dimension of the internal element in the thickness direction are made the same and divided into one in the thickness direction. FIG. 6 described above shows an example in which the surface element 2 and the internal element 1 are displayed in the same space, and the surface element 2 and the internal element 1 are overlapped (overlapped) in the analysis space.

  The surface elements and internal elements created through such a process are configured in the following form as the coordinates of each element node and the node number constituting each element in the database (DB). That is, as shown in FIG. 2, the following DB3 and DB4 are generated by the database generation unit 29 as databases related to internal elements (I elements).

DB3) Node coordinates indicating the coordinates of the nodes of the internal element: Node number n ^I _k = (x _k , y _k , z _k )
DB4) Node numbers constituting internal elements: element numbers e ^I _l = (n ^I , n ^I ,..., N ^I )
However,
k = 1 to (total number of nodes of internal elements)
l = 1 to (total number of internal elements)

  As shown in FIG. 2, the following DB5 and DB6 are generated by the database generation unit 29 as databases related to internal elements (S elements).

DB5) Node coordinates of surface element nodes: Node number n ^S _i = (x _i , y _i , z _i )
DB6) Node number constituting the surface element: element number e ^S _j = (n ^S , n ^S ,..., N ^S )
However,
i = 1 to (the total number of nodes of the surface element)
j = 1 to (total number of surface elements)

  The analysis model creation apparatus 20 according to the present embodiment uses the databases DB3 to DB5 among the four databases DB3 to DB6 to detect surface elements included in the internal elements and convert them into a DB (shown in FIG. 2). It has operation 3). This calculation process is performed in order to perform the following calculation and DB conversion at high speed after the calculation process is executed.

  On the other hand, the database generation unit 29 cooperates with the displacement information setting unit 23 to generate the DB 8 by the displacement transmission amount calculation (calculation 4) between the surface element and the internal element as shown in FIG. That is, for a specific node of a surface element that overlaps with an internal element, using the relative position (vector quantity) with a nearby internal element node, the displacement transmission relationship between the two is calculated to generate DB8. Further, the database generation unit 29 cooperates with the rigidity information setting unit 23 to generate the DB 9 by the rigidity calculation (calculation 5) of each internal element overlapping with the surface element. That is, for each internal element, the DB 9 is constructed by calculating the rigidity such as the elastic modulus of the internal element from the excluded shape part excluding the part (shape part) overlapping with the surface element.

  In the above calculations 4 and 5, the node coordinates DB3 and DB5 obtained from the calculations 1 and 2 and the node numbers DB4 and DB6 constituting each element are required. In a large-scale analysis model, The number of data lines in the database becomes enormous, and a lot of time is spent searching for various data, and as a result, a great deal of time is required for computation for analysis modeling.

  Therefore, as shown in FIG. 2, the analysis model creation apparatus 20 performs the computation 3 and constructs the DB 7 before the computation 4 and the computation 5, thereby greatly reducing the creation time of the analysis model. Make it possible. That is, the database generation unit 29 of the analysis model creation device 20 determines the rigidity (elastic modulus such as Young's modulus) of the internal element from the excluded shape portion excluding the portion overlapping the surface element for each internal element. Calculate and create a database.

  A specific example of the calculation 3 by the database generation unit 29 will be described with reference to FIGS. The database generation unit 29 reads the constituent coordinates of individual internal elements (coordinate values of the internal element node 3) from DB3 and DB4 with respect to the coordinate values of the node 4 of the surface element randomly read from DB5. It is determined whether or not the internal element includes the surface element.

  For this determination, the database generation unit 29, for example, as shown in FIGS. 7 and 8, has a square pyramid (one in the case of FIG. Calculate the volume sum of 5 (6 square pyramids are defined per internal element). As shown in FIG. 7, when the node 4 of the surface element is included in the internal element 1, the total volume of the six square weights matches the volume of the single internal element. On the other hand, as shown in FIG. 8, when the node 4 of the surface element is not included in the internal element 1, the volumes do not match. The database generation unit 29 selects all the nodes of the surface element included in the internal element by this determination, and shows the correspondence between the surface element node number of the surface element and the internal element number of the internal element including the surface element in FIG. Create DB7. After obtaining this DB 7, calculations 4 and 5 are performed.

  Next, a specific example of the calculation 4 by the displacement information setting unit 23 will be described with reference to FIG. FIG. 9 shows a case where the internal elements are projected onto the local coordinate system (ξ, η, ζ) = (− 1 to 1, −1 to 1, −1 to 1). In this local coordinate system, when the coordinate value of the node (Node) of the included surface element is (ξ, η, ζ), the displacement information setting unit 23 uses an interpolation function of an isoparametric primary element. Then, the displacement (υ, ν, ω) of the node of the surface element is defined by the following equations [1] to [9], respectively.

N ₁ = 1/8 · (1-ξ) · (1-η) · (1-ζ) Formula [2]
N ₂ = 1/8 · (1 + ξ) · (1−η) · (1−ζ) Formula [3]
N ₃ = 1/8 · (1 + ξ) · (1 + η) · (1−ζ) Formula [4]
N ₄ = 1/8 · (1−ξ) · (1 + η) · (1−ζ) Formula [5]
N ₅ = 1/8 · (1−ξ) · (1−η) · (1 + ζ) Equation [6]
N ₆ = 1/8 · (1 + ξ) · (1−η) · (1 + ζ) Formula [7]
N ₇ = 1/8 · (1 + ξ) · (1 + η) · (1 + ζ) Formula [8]
_{N 8 = 1/8 · (} 1-ξ) · (1 + η) · (1 + ζ) ... the formula [9]

However,
υ, ν, ω: Displacement of node of surface element υ _i , ν _i , ω _i : Displacement of node i of internal element ξ, η, ζ: Surface element node coordinates in local coordinate system

  By using the above equations [1] to [9], it is possible to minimize the displacement transmission error caused by the difference in coordinates between the nodes of the surface elements and the nodes of the internal elements, thereby enabling highly accurate analysis. Become.

  Furthermore, a specific example of the calculation 5 by the stiffness information setting unit 23 will be described with reference to FIGS. In the calculation 5, the shape dimension when the shape overlapping with the surface element is excluded is obtained for each internal element, and the rigidity value of the internal element is calculated from the same shape to create a DB. First, an example of calculation of a shape dimension when a shape overlapping with a surface element is excluded will be described below.

FIG. 10 shows an internal element 8 that includes the node N ₁ of the surface element and the node N ₁ (node 7) of the surface element read from the DB 7. FIG. 10 also shows surface element nodes N _{2 to} N ₅ adjacent to the surface element node N ₁ . Surface element node N ₂ to N ₅ is obtained by using a DB5 and DB 6. In the calculation 5, as shown in FIG. 10, the intersections n _{1 to} n ₄ of the inner element surfaces are obtained from the planes S _{1 to} S ₄ composed of the surface element node N ₁ and the surface element nodes N _{2 to} N ₅ .

Specifically, for example, the intersection point n ₁ is calculated by solving the definition function of the plane S _{1 and} the definition function of two element surfaces (for example, S ₁ and S ₂ ) constituting the internal element 8. If the intersections of the three planes are not parallel, a solution is always obtained. On the other hand, depending on the combination of the two element surfaces constituting the internal element, there can be obtained a case where the calculated intersection is not on the internal element component surface. However, in these detections, in the calculation 5, by confirming the inclusion property of the intersection calculated using the inclusion calculation illustrated in FIG. 7 and FIG. 8, the intersection on each surface constituting the internal element is surely determined. Can be calculated.

FIG. 11 shows the internal element 8 calculated by the above calculation and the intersections n _{1 to} n ₄ (11) on the constituent surface of the internal element 8 and intersecting the surface element surface. As shown in FIG. 11, n _{1 to} n ₄ do not exist on the same plane, but in order to easily determine the shape dimensions, n _{1 to} n ₄ are crossed again by the least square method using the least square method. A surface 12 is defined. With this calculation, it is possible to determine the shape dimensions of the internal elements when shapes that overlap with the surface elements are excluded.

  Next, the rigidity value of the internal element is calculated from this shape, and the DB 9 is generated by correcting the rigidity value of the internal element defined in the input term 2. A specific example will be described with reference to FIG. As shown in FIG. 12, the stiffness information setting unit 23 uses a shape obtained by projecting a shape excluding a portion overlapping with a surface element among internal elements that are three-dimensional elements onto an orthogonal coordinate system [10 ] Is determined.

R _i = S _jk ^P / S _jk ^v , R _j = S _ki ^P / S _ki ^v , R _k = S _ij ^P / S _ij ^v (10)
However, for example,
R _i : Projected area ratio for the jk plane perpendicular to the i direction in FIG. 12 S _jk ^P : Area of the shape projected on the jk plane in FIG. 12 S _jk ^v : Interior projected on the jk plane in FIG. Element area

  The rigidity information setting unit 23 cooperating with the database creation unit 29 uses the projection area ratio calculated by the above equation [10], performs calculations using the following equations [11] to [14], The elastic modulus of the internal element is recalculated, and the result of this recalculation is stored in DB9. More specifically, the DB 9 stores an internal element number of an internal element that overlaps with a surface element and an elastic modulus (such as Young's modulus) newly calculated for the internal element in association with each other.

E _ii = R _i · E _ii ^v , E _jj = R _j · E _jj ^v , E _kk = R _k · E _kk ^v ... Formula [11]
G _ij = (R _i + R _j ) · G _ij ^v / 2 Equation [12]
G _jk = (R _j + R _k ) · G _jk ^v / 2 Equation [13]
G _ki = (R _k + R _i ) · G _ki ^v / 2 Equation [14]
However,
E _ii ^v , E _jj ^v , E _kk ^v , G _ij ^v , G _jk ^v , and G _ki ^v are the stiffness values of the internal elements defined in the initial stage.

  By this calculation, it is possible to reduce the rigidity of the internal element defined by DB2 that overlaps with the surface element and has once increased in accordance with the cross-sectional area of the overlapping shape in the deformation direction. . Thereby, a highly accurate structural analysis result can be obtained.

  After creation of DB 9 by the above operation 5, the structural analysis processing unit 27 performs structural analysis using DB2 to DB6 and DB8, 9 necessary for input of the analysis file, and further analyzes the result of the structural analysis. The result output unit 28 outputs an analysis input file (analysis model) that complies with, for example, the input rules of the structural analysis solver (software).

  In this embodiment, it is possible to automatically create an analysis file simply by specifying the input terms 1 to 4, and it is possible to greatly reduce the labor of the analyst's file creation compared to the conventional method. . Furthermore, by performing the calculations 4 and 5 via the DB 7 by the calculation 3, it is possible to reduce the calculation amount and the element search amount necessary for creating the DB8 and DB9. For this reason, it is possible to reduce not only the labor of the analyst but also the calculation time and creation time for creating the model file.

  FIG. 13 shows an analysis result by the analysis model created by the analysis model creation device 20. On the other hand, FIG. 14 shows an analysis result by a conventional analysis model modeled by a plurality of hexahedral elements each having an arbitrarily defined shape as a comparative example. The analysis results in FIGS. 13 and 14 are obtained by performing stress analysis and displaying the surface stress generated on the model surface (curved portion) in a contour diagram of the same range. Note that FIG. 13 illustrates the surface elements and the internal elements that are virtually shifted to facilitate evaluation of the analysis result.

  As shown in FIGS. 13 and 14, it can be seen that the bending portion (evaluation site) of the analysis model created by the analysis model creation device 20 gives at least the same stress analysis result as in the comparative example. Further, FIG. 15 shows the analysis accuracy of the stress value generated at each node of the curved portion (surface element) in the analysis results of FIGS. 13 and 14. Most of the analysis results (analysis values in FIG. 10) of the analysis model of the present embodiment are within ± 10% of the stress value range with respect to the analysis results of the analysis model of the comparative example, and this embodiment is excellent. It can be seen that the analysis results are given.

  As described above, according to the analysis model creation device 20 according to the present embodiment, the analysis model creation time can be shortened and the analysis accuracy can be improved.

<Second Embodiment>
Next, a second embodiment will be described based on FIGS. 16 to 18C. In FIG. 16, the same components as those in FIG. 1 described in the first embodiment are given the same reference numerals, and redundant descriptions are omitted. As shown in FIGS. 16 and 17, the structural analysis system 50 including the analysis model creation device 40 according to the present embodiment is replaced with the database generation unit 29 provided in the analysis model creation device 20 of the first embodiment. The database generation unit 49 is provided.

  As shown in FIG. 17, the database generation unit 49 creates a surface element node inclusion calculation list as DB 6 as a list for specifying the nodes of the surface elements to be included in the calculation when performing calculation 2 based on the input item 4. To do. As a result, it is possible to reduce the calculation amount of the operation 3 and to create an analysis model more quickly. In other words, the database generated by the database generation unit 49 specifies some nodes selected according to the specified condition from among the nodes of each of the plurality of divided surface elements (second divided elements). It includes a database that stores information to be stored.

  Processing for generating the surface element nodal inclusion calculation list (DB6) will be described mainly based on FIGS. 18A to 18C. In FIGS. 18A to 18C, a two-dimensional configuration will be described as an example in order to clarify the technical contents of the present embodiment. FIG. 18A shows CAD data at the previous stage of input in the input item 2. The CAD data includes a plurality of coordinate data 16 and shape surface data (curved surface data) 17 representing the shape of the surface including these coordinate data 16.

  As shown in FIG. 18A, when creating a surface element for curved surface data, first, as shown in FIG. 18B, the second division processing unit 22 divides the curved surface and sets the node 18 of the surface element as a division point. Deploy. This division size is automatically determined by the element size defined in the input item 2. Thereafter, as shown in FIG. 18C, the second division processing unit 22 pushes nodes from the surface on the CAD data to the inside of the model (model of the internal element) to create a surface element.

  At this time, the push-out amount of each node is automatically determined by the thickness of the surface element defined by the input item 2. Here, the database generation unit 49 of the present embodiment cooperates with the second division processing unit 22 to create a newly created internal node (node on the internal side of the surface element) as shown in FIG. 18C. DB6 shown in FIG. 17 in which 19 is listed in advance is generated.

  The DB 6 is applied as a surface element candidate for performing an inclusion calculation in the subsequent operation 3. That is, as illustrated in FIG. 18B, the database generation unit 49 excludes the division point (specific node in the surface element) when dividing the curved surface data of the CAD data from the target of the calculation 3, thereby calculating the calculation 3. The amount can be reduced and the DB 8 can be created at a higher speed. In this embodiment, although the above-described surface element division points shown in FIG. 18B are excluded from the analysis target, it is considered that the degradation to the analysis accuracy is small.

  In the first embodiment, when defining the elastic modulus (rigidity) of the internal element, as shown in FIG. 12, the internal element greatly overlapping with the surface element is defined to have a small elastic modulus, The influence on the analysis result is smaller than the internal elements. That is, since the internal element approximated to the curved surface data shown in FIG. 18A largely overlaps with the surface element of FIG. 18C, it can be said that the elastic modulus is low and the influence on the analysis result is small.

  For this reason, even if the node (division point) 18 of the surface element shown in FIG. 18B is excluded from the analysis target in the calculation 4, the analysis result is not greatly affected. Further, in the calculation 5, an internal element that overlaps (overlaps with) the surface element and its shape can be obtained. As shown in FIG. 18C, the nodes of the listed candidate surface elements that perform the inclusion calculation are applied. Thus, the cut surface of the internal element can be calculated. For this reason, this embodiment can ensure substantially the same analysis accuracy as compared with the first embodiment. As described above, in this embodiment, it is possible to reduce the calculation load of calculation 3 to calculation 5 while suppressing the influence on the analysis accuracy. This is expected to shorten the creation time of the analysis model.

<Third Embodiment>
Next, a third embodiment will be described based on FIGS. 19 to 21C. 19 to 21C, the same components as those in FIGS. 16 to 18C described in the second embodiment are denoted by the same reference numerals, and redundant description is omitted. As shown in FIGS. 19 and 20, the structural analysis system 70 including the analysis model creation device 60 according to the present embodiment is replaced with a database generation unit 49 provided in the analysis model creation device 40 of the second embodiment. The database generation unit 69 is provided.

  The database generated by the database generation unit 69 of the present embodiment specifies an internal element that is close to the surface element (second divided element) among the plurality of divided internal elements (first divided element). It has a database that stores information. Specifically, as illustrated in FIG. 20, the database generation unit 69 performs an operation 2 based on the input item 4, in addition to generating DB 5 and DB 7, based on DB 3 and DB 4 A DB 6 in which elements are detected and listed is generated. As a result, the amount of computation 3 can be reduced, and an analysis model can be created and output more quickly.

  Processing for defining DB6 shown in FIG. 20 will be described with reference to FIGS. 21A to 21C. 21A to 21C, a two-dimensional configuration will be described as an example in order to clarify technical features. FIG. 21A shows a state in which the CAD data before the input in the input item 4 and the internal element 1 exist at the same time. As shown in FIGS. 21A and 21B, the process of creating the surface element based on the CAD data is the same as the content described in the second embodiment.

  However, when the database generation unit 69 of the present embodiment creates a surface element on the inner side of the analysis model while cooperating with the second division processing unit 22, the internal element adjacent to the surface element is set to a certain range. Detect over. As shown in FIG. 21C, for a newly created surface element (node inside CAD data), it is included in a preset detection distance (a circle determined by a predetermined radius 35 centered on the node of the surface element, for example). The internal element number of the internal element having the searched node is stored in the DB 6 as a nearby internal element list.

  Therefore, in the analysis model creation device 60 of the present embodiment, in order to determine whether or not an internal element includes a surface element by a simple calculation using a definition function such as a circle or a sphere that defines the detection range described above. It is possible to easily acquire the information (inclusiveness), and this can reduce the amount of calculation in creating the analysis model. Further, for example, when general-purpose application software is used, when the calculation 2 shown in FIG. 20 is executed, the calculation for creating DB5 and DB7 and the calculation for creating DB6 (proximity internal element list) are executed simultaneously. Thus, an increase in calculation load can be suppressed. Furthermore, by configuring an analysis model creation device that uses both the DB 6 shown in FIG. 20 of the present embodiment and the DB 6 shown in FIG. 17 of the second embodiment, the amount of calculation for creating the analysis model is greatly increased. Can be reduced.

  According to at least one embodiment described above, the analysis model creation time can be shortened and the analysis accuracy can be increased.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,8 ... Internal element, 2 ... Surface element, 3 ... Node of internal element, 4, 7 ... Node of surface element, 30, 50, 70 ... Structural analysis system, 20, 40, 60 ... Analysis model creation apparatus, 21 ... 1st division processing part, 22 ... 2nd division processing part, 29, 49, 69 ... Database generation part, 23 ... Displacement information setting part, 24 ... Stiffness information setting part, 25 ... Analysis model creation processing part, 26 ... CAD Data acquisition unit, 27... Structure analysis processing unit, 28... Analysis result output unit.

Claims (6)

A first division processing unit that divides the entire region corresponding to the shape of the analysis object into a plurality of first division elements having a regular shape;
A second division processing unit that divides an edge portion of the entire region corresponding to the shape of the analysis object into a plurality of second division elements having an arbitrarily defined shape;
A database generation unit for generating a database having information indicating positions of at least nodes of the plurality of divided first and second divided elements;
While referring to the generated database, the relative positional relationship between the nodes of the first and second division elements having overlapping regions is obtained, and based on the obtained relative positional relationship, A displacement information setting unit configured to set information on the displacement of the mutual nodes when stress is applied to the analysis target;
While referring to the generated database, the degree of overlap between the first and second division elements having the overlapping area is obtained, and the division element having the overlapping area is determined based on the obtained degree of overlap. A rigidity information setting unit for setting information on rigidity,
An analysis model creation processing unit for creating an analysis model by incorporating information on the set displacement and information on rigidity; and
An analysis model creation device comprising: The database generated by the database generation unit is a database that stores information for identifying a first divided element that includes a node of the second divided element among the plurality of divided first divided elements. including,
The analysis model creation device according to claim 1. The database generated by the database generation unit stores information for identifying a part of nodes selected according to a specified condition from among the nodes of each of the plurality of divided second divided elements. Including database,
The analysis model creation apparatus according to claim 1 or 2. The database generated by the database generation unit includes a database in which information specifying a first divided element close to the second divided element among the plurality of divided first divided elements is stored. ,
The analysis model creation device according to any one of claims 1 to 3. A first division processing unit that divides the entire region corresponding to the shape of the analysis object into a plurality of first division elements having a regular shape;
A second division processing unit that divides an edge portion of the entire region corresponding to the shape of the analysis object into a plurality of second division elements having an arbitrarily defined shape;
A database generation unit for generating a database including information indicating positions of at least nodes of the plurality of divided first and second divided elements;
While referring to the generated database, the relative positional relationship between the nodes of the first and second division elements having overlapping regions is obtained, and based on the obtained relative positional relationship, A displacement information setting unit configured to set information on the displacement of the mutual nodes when stress is applied to the analysis target;
While referring to the generated database, the degree of overlap between the first and second division elements having the overlapping area is obtained, and the division element having the overlapping area is determined based on the obtained degree of overlap. A rigidity information setting unit for setting information on rigidity,
An analysis model creation processing unit for creating an analysis model by taking in information on the set displacement and information on rigidity,
An analysis model creation program that allows a computer to function as a computer. Dividing the entire region corresponding to the shape of the analysis object into a plurality of first division elements having a regular shape;
Dividing an edge of the entire region corresponding to the shape of the analysis object into a plurality of second division elements having an arbitrarily defined shape;
Generating a database including information indicating positions of at least nodes of the plurality of divided first and second divided elements;
While referring to the generated database, the relative positional relationship between the nodes of the first and second division elements having overlapping regions is obtained, and based on the obtained relative positional relationship, Setting information on the displacement of the mutual nodes when stress is applied to the analysis object;
While referring to the generated database, the degree of overlap between the first and second division elements having the overlapping area is obtained, and the division element having the overlapping area is determined based on the obtained degree of overlap. Setting information on stiffness for
Taking in the information on the set displacement and information on the rigidity to create an analysis model;
An analysis model creation method having

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