JP2007293382A - Thermal analysis unit, thermal analysis method, and thermal analysis transaction program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize temperature distributions in a metal mold or the like by expressing a shape including a fine concavo-convex portion by a structure in large and small hexahedral meshes of minimum necessary number and thermally analyzing it. <P>SOLUTION: A thermally analyzing method comprises a step 11 of splitting and defining an optional spatial domain which includes a space where a three-dimensional model for analysis exists as a fine hexahedral mesh spatial domain, a step 12 of determining a physical property of the fine hexahedral mesh spatial domain, a step 13 of collectively redefining a plurality of the fine hexahedral mesh spatial domain as one minute fine hexahedral mesh spatial domain when the physical properties of adjacent fine hexahedral spatial domains are the same, a step 14 of creating the hexahedral mesh of calculating the spatial domain size of the fine hexahedral mesh spatial domain redefined, respectively, a step 15 of joint processing which gives continuity to the hexahedral mesh spatial domain for calculation by mathematically averaging the state variable of unjoined mesh nodes by mathematically averaging the state variable of the unjoined mesh nodes by a nearby node for the created hexahedral mesh for calculation and averaging the state variables according to the physical properties of the elements to be joined, and a step 16 of analyzing the analytic model of the hexahedral mesh. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermal analysis apparatus, a thermal analysis method, and a thermal analysis processing program for creating a calculation mesh for a finite element method, a finite volume method, or a finite difference method and performing thermal analysis.

  Conventionally, in the mold design, it is necessary to determine the position of the gate so that the resin is efficiently filled in the mold and the weld line does not appear on the appearance surface, and the simulation predicts the resin flow during filling Is well done.

  On the other hand, if the mold is not opened when the resin is solidified, the soft molding resin that has not been solidified by the impact at the time of mold release will cause the mold to lose its shape. It is necessary to cool below the melting point or glass transition point (Tg point) in a short time.

  However, in the region close to the gate position, new hot resins are filled one after another, so that it is difficult to cool. Moreover, the thick part is hard to cool, and the thin part is cooled quickly. Since these affect each other in a complex manner, the temperature distribution that is intuitively considered is different, so there are many cases where a water-cooled tube is added after the mold is actually manufactured. Therefore, in order to reduce such trial and error, it is desired to obtain a temperature distribution using a simulator.

  Even in the resin flow simulator, it is possible to calculate the cooling distribution in the filling state in consideration of the gate position to some extent. However, in reality, many water pipes are arranged in the mold to cool the resin, and there is an error in the method of ignoring the influence of the three-dimensional water pipe distance and predicting the mold as a constant temperature. As a result, there was a limit to the exact layout design of the water pipe. In addition, even if calculations that take such effects into account are possible, when automatically importing piping positions and product shape from a 3D CAD model, even if you try to automatically model, If the chamfering and screw holes are omitted, the model will be fine and enormous, and as a result, minor inconsistencies must be corrected in the Boolean operation during shape input. It was a bottleneck that a lot of man-hours had to be spent by then. In addition, as a method for solving this modeling automation, a method has been proposed in which all shapes are represented by a microcube called VOXCELCON, all the shapes are modeled and corrected for numerical simulation. Then, since all models are expressed by a cube of the minimum size that expresses the shape of the minimum part, the display data, calculation data, and calculation result data become very large, so dedicated software is necessary. The modeling and result display operations are also very heavy and complicated. In addition, when the data has non-linearity, the matrix calculation becomes enormous, and there is a problem such as a long calculation time.

  Conventionally, such a mesh is automatically created, the target mesh to be thinned out is selected from the side length and shape of the created mesh, and the thinning process can be performed to improve analysis accuracy and shorten calculation time (For example, refer to Patent Document 1).

JP 2003-30255 A

  By the way, in the cooling pipe arrangement design of the mold, in order to cool the molding resin efficiently, it is necessary to grasp the molding resin temperature distribution for each change over time, and to place the water pipe close to the slow cooling part or to arrange many. is there.

  The model written in 3DCAD usually has a lot of chamfering information, draft angle, fine bosses / holes, ribs, etc. that are not necessary for heat conduction calculation / stress calculation. If it is modeled for use, the number of elements will be enormous. For this reason, it is normal to create an analysis model while simplifying shapes that are not necessary for analysis, but in the case of complex structures such as a mold model, such correction work takes a lot of time. Cost is required.

  Modeling with cubic elements (cells) of uniform shape and size can speed up the calculation by partially omitting matrix operations, but offsets the increase in the number of elements (cells). However, depending on the model, the elements that are originally rough may be uniformly finer, so the number of elements becomes enormous, and the calculation model created using the general automatic mesh function is larger. The calculation time is greatly increased. In addition, since data is enormous regarding condition setting and result display processing, enormous work time is required. Since a calculation program different from general analysis software is required, if you want to add nonlinear behavior calculation, you need to write the software from the beginning.

  Therefore, in view of the conventional problems as described above, the object of the present invention is to create a calculation mesh for the finite element method, the finite volume method, or the finite difference method, and to minimize the shape including the fine irregularities. The object is to provide a thermal analysis apparatus, a thermal analysis method, and a thermal analysis processing program capable of expressing a structure with large and small hexahedral meshes, performing thermal analysis, and optimizing a temperature distribution of a mold or the like.

  Other objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of embodiments described below.

  The present invention is a thermal analysis apparatus that performs thermal analysis by creating a finite element method, a finite volume method, or a finite difference method calculation mesh, and includes any space that includes a space where a three-dimensional model to be analyzed exists. A minute space region creating unit that divides and defines a region into minute hexahedral space regions, a physical property value determining unit that determines physical property values of the minute hexahedral space region created by the minute space region creating unit, and a plurality of adjacent minute When the physical property values of the hexahedron space region are the same, a micro space region redefinition unit that redefines the plurality of micro hexahedron space regions as one micro hexahedron space region, and an unconnected mesh node Discontinuous mesh concatenation is performed in which state variables are mathematically averaged at nearby nodes and weighted according to the physical properties of the elements to be joined, thereby averaging the calculation mesh. , A calculation hexahedral mesh creation unit that creates a hexahedral mesh for calculation redefined in each spatial region according to a defined spatial region size, and a calculation created by the calculation hexahedral mesh creation unit. And a thermal analysis processing unit that analyzes the analysis model indicated by the hexahedral mesh.

  Further, the present invention is a thermal analysis method for performing thermal analysis by creating a finite element method, a finite volume method, or a finite difference method calculation mesh, and includes an arbitrary space including a space where a three-dimensional model to be analyzed exists. Are divided into micro hexahedral space areas, the physical property values of the micro hexahedral space areas are determined, and the physical values of a plurality of adjacent micro hexahedral space areas are the same. The hexahedral space region is redefined as one micro hexahedral space region, the state variables of unconnected mesh nodes are mathematically averaged at nearby nodes, and weighted according to the physical properties of the joined elements The calculation meshes are processed to give continuity, and the calculation hexahedral meshes are redefined in the respective spatial regions according to the defined spatial region sizes. The analysis model shown by calculation hexahedral mesh, characterized by performing the analysis.

  Furthermore, the present invention is a thermal analysis processing program for creating a finite element method, a finite volume method, or a finite difference method calculation mesh and performing thermal analysis by a computer, wherein a space where a three-dimensional model to be analyzed exists is present. A micro space region creating process for dividing and defining an arbitrary spatial region to be divided into micro hexahedral space regions; a physical property value determining process for determining physical property values of the micro hexahedral space region created by the micro space region creating unit; A micro space region redefinition process for redefining the plurality of micro hexahedron space regions as a single micro hexahedron space region when physical properties of adjacent micro hexahedron space regions are the same; The state variables of the mesh node of the connection are mathematically averaged at nearby nodes, and further weighted according to the physical properties of the elements to be joined, and then averaged. For discontinuous mesh combination processing for performing continuity processing, and for calculating hexahedral mesh for calculation redefined in each spatial region by the spatial region size defined by the above-mentioned micro space region redefinition processing The computer is configured to execute a hexahedral mesh creation process and a thermal analysis process for analyzing the analysis model indicated by the calculation hexahedral mesh created by the calculation hexahedral mesh creation process.

  In the present invention, a finite element method, a finite volume method, or a finite difference method calculation mesh is created, and a structure including a fine uneven portion is expressed by a minimum and large hexahedral mesh and subjected to thermal analysis. The temperature distribution of the mold can be optimized.

  In the present invention, the minimum size cell determined by the analyst himself / herself is automatically determined whether or not the object exists in the divided space, and whether the shape is present or not can be greatly automated. Thus, since the number of corrections is small, the calculation cost can be greatly reduced.

  In the present invention, since calculation (sharing) can be performed with commercially available analysis software, it is possible to effectively utilize the software infrastructure on the market. Further, since the number of elements is reduced, the calculation matrix can be greatly reduced and the calculation time can be shortened. Since the number of elements can be reduced in any of x, y, and z directions, the mesh can be greatly reduced. The minimum cell shape can be partially changed between the finely expressed area and the rough area, and the number of elements can be reduced and the calculation time can be shortened.

  In the present invention, the mesh aspect ratio is not easily influenced by the shape, a stable solution is easily obtained, and calculation with good convergence is possible. In addition, since the arrangement of the meshes is orderly, it is easy to automate the definition, for example, by scanning the shape data to be converted at regular intervals and discharging the state with the data. Furthermore, the discontinuous mesh portion is defined by averaging the information of adjacent nodes, but the definition is easy because the information discharged to the nodes and integration points by a commercially available solver can be used. Even if a large number of discontinuous junctions are used, in the case of heat conduction calculations, in the case of linear primary elements, the temperature gradient within the element is expressed by a linear linear gradient, and it is difficult for inconsistencies and discontinuities to occur at the joints. There are few errors.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Needless to say, the present invention is not limited to the following examples, and can be arbitrarily changed without departing from the gist of the present invention.

  The present invention is applied to a thermal analysis apparatus 100 that performs thermal analysis by creating a calculation mesh of a finite element method, a finite volume method, or a finite difference method, for example, configured as shown in FIG.

  The thermal analysis apparatus 100 reads shape information from 3D_CAD (Computer-Aided Design) and reflects the external shape information on the FEM mesh model or the mesh model for the finite volume method. The mesh creation processing unit 10 to be performed, the input / output data processing unit 20 connected to the mesh creation processing unit 10, the discontinuous mesh unit combination computation unit 30, the mesh re-refining determination unit 40, the storage unit 50, the post-processing unit 60, etc. Consists of.

  The mesh creation processing unit 10 reads the 3D_CAD data, and defines a microspace region creation unit 11 that divides and defines an arbitrary space region including a space in which a three-dimensional model to be analyzed exists into a microhexahedral space region, the microspace region The physical property value determining unit 12 that determines the physical property value of the micro hexahedral space region created by the creating unit 11, and the plurality of micro hexahedral spaces when the physical property values of a plurality of adjacent micro hexahedral space regions are the same. A micro space region redefinition unit 13 for redefining a region as one micro hexahedral space region, and a calculation redefined for each space region by the space region size defined by the micro space region redefinition unit 13. 6 planes for calculation created by the hexahedral mesh creation unit for calculation 14 for creating a hexahedral mesh for calculation, and the 6 plane mesh creation unit for calculation 14 described above. For meshes, the state variables of unconnected mesh nodes are mathematically averaged at neighboring nodes, and further, weighted according to the physical properties of the joined elements, and averaged, thereby providing continuity to the computational hexahedral mesh. A discontinuous mesh combining unit 15 that performs processing, a thermal analysis processing unit 16 that performs analysis on the analysis model indicated by the calculation hexahedron mesh that has been combined by the discontinuous mesh combining unit 15, and the like. . The minute space region redefining unit 13 includes a primary merge determining unit 13-1, a secondary merge determining unit 13-2,..., An nth merge determining unit 13-n.

  In this thermal analysis apparatus 100, for example, when the outer shape of the analysis object and the size of one mesh (square) are determined by a user input or the like, the information is transferred to the mesh creation processing unit via the input / output data processing unit 20. 10 is input.

  The mesh creation processing unit 10 reads 3D_CAD data, and the minute space region creation unit 11 divides and defines an arbitrary space region 120 including the space in which the three-dimensional model 110 to be analyzed exists into a minute hexahedral space region 130. . In this process, the physical property value specifying unit 12 determines the physical property value of each micro hexahedral space region 130 created by the micro space region creating unit 11 based on 3D_CAD data.

  That is, in the minute space region creation unit 11, for example, as shown in FIG. 2, an arbitrary conversion region 120 including 3D_CAD data to be converted into a calculation model is set, and the range of the conversion region 120 is set in the x, y, and z directions. Then, each is divided at a pitch of an arbitrary size to define a micro hexahedral space region 130 of a certain size. In this process, the physical property value specifying unit 12 sequentially inputs the center coordinates x, y, and z coordinates of each minute hexahedral space region 130 to the 3D_CAD information determination function 3DCAD_MAT_INF and outputs it for each minute hexahedral space region. The structure information is defined together with the ID information of the minute hexahedral space region.

  3D_CAD information determination function 3DCAD_MAT_INF (X, Y, Z) refers to 3D_CAD data when X, Y, Z coordinates based on the coordinate axes defined on 3D_CAD are input, and predetermined material properties (MAT1, MAT2, MAT3, MAT4, etc.) [1] if the data of the X, Y, Z coordinate position is data of material properties (MAT1), [2] if the data of material properties (MAT2) is [2], and so on. [3] in the coordinates of the material physical property (MAT3),...

  The minute space region redefinition unit 13 determines the minute hexahedral space region 130 created by the minute space region creation unit 11 by the physical property value specification unit 12 in the primary merge determination unit 13-1. Based on the information, the primary merge determination is performed. The merge determination is, for example, a micro hexahedral space area adjacent to the xyz coordinate in the plus direction in the reference micro hexahedron space area, for example, as shown in FIG. The determination is made by the individual micro-hexahedral space regions 130 (000), 130 (100), ..., 130 (111). For example, in the case where all of the eight micro hexahedral space regions 130 (000), 130 (100),..., 130 (111) are the material physical property MAT1, the eight micro hexahedral space regions 130 (000), The merge determination index 8 is determined for all 130 (100),..., 130 (111). If at least one of the eight micro hexahedral space regions 130 (000), 130 (100),..., 130 (111) is not a material property (MAT1), the merge determination index remains [1]. is there. Further, as shown in FIG. 4, the eight adjacent micro hexahedral space regions 130 (222), 130 (322),..., 130 (333) are sequentially checked, and the merge determination index is set. I will decide. For example, this work is checked for each of the eight small hexahedral space regions in the order of priority of X, Y, and Z. In other words, as shown in Fig. 5, when one column check in the X direction is completed, the check proceeds to the next column, and when all the Y direction is completed, the check is performed in the same manner by moving to the upper stage in the Z direction. To do.

  If the determination of the eight micro-hexahedral space regions ends in all of the specified transformation regions, the next is similarly doubled by the side (23 times in terms of volume) and 64 micro-space regions The secondary merge determination unit 13-2 performs secondary merge determination for determining the merge determination index every time. However, in the merge determination of 64 minute space areas, if the adjacent merge determination area is not 8 which is the determination index of one lower rank, that is, if the determination index is 1, the determination of 8 remains as it is. And

  Next to the 64 minute space regions, the same merge determination is performed for 512 minute space regions. In this case as well, if it is not 64, which is the determination index of one lower rank, that is, if the determination index is 1 or 8, the determination index is 64 as it is. These processes are repeated, and the determination increased by 23 times is performed for all the minute space regions.

  For example, if the space is divided by the number of divisions divisible by 64, the minute space region can be determined without any fractions until at least 64 determinations are made. If a fraction is given, the decision index is checked as the decision index is kept at its highest value.

  Similarly, the N-th order merge determination by the N-th order merge determination unit 13-n is performed, and after the merge determination up to the specified arbitrary size is completed, the calculation hexahedral mesh is generated based on the determination result. The unit 14 creates a mesh based on numerical analysis such as a finite element method.

  In the case of a minute space region with a determination index of 1, the calculation hexahedral mesh creating unit 14 defines the mesh with the shape of the minute space region itself. After checking and redefining the decision index 1 for all the minute space regions, the decision index 8 is checked. In the case of this determination, the check, that is, the mesh creation determination and the accompanying mesh creation are performed only in the minute space area A that is the smallest in the x, y, and z directions among the eight minute space areas that have been determined. . When the determination index is 8, mesh creation is performed with the size of eight minute space areas. The same applies to the determination indices 64 and 512.

  Here, the calculation hexahedron mesh created by the calculation hexahedron mesh creating unit 14 in this way is the same when the determination indices of the micro hexahedron space region that is the basis of the mesh are the same, Although it becomes a continuous mesh, the part which cannot share a node generate | occur | produces in the adjacent surface of things with different judgment indices. Therefore, an unjoined mesh node is obtained for the calculation hexahedron mesh created by the calculation hexahedron mesh creating unit 14 by the discontinuous mesh joining processing unit 15 based on the computation result by the discontinuous mesh part joining computation unit 30. The state variables of are mathematically averaged at nearby nodes, and further, weighted according to the physical properties of the joined elements, and averaged to perform continuity to the hexahedral mesh for calculation, for example, As shown in FIG. 6, when the mesh M1 created with the decision index [1] and the mesh M8 created with the decision index [8] are adjacent to each other, the discontinuous nodes that cannot share the node between the center portion and the center of the ridge line For Nc and node Nd, state variables such as temperature and displacement are Nc = (N1 + N2 + N3 + N4) / 4, Nd = (N1 + N2) / 2, for example. Sea urchin, complemented mathematically averaged state variable of neighboring nodes. As a result, it is possible to give pseudo continuity to an unconnected portion where nodes are not shared in analysis.

  The thermal analysis processing unit 16 analyzes the analysis model indicated by the calculation hexahedron mesh that has been subjected to the coupling process by the discontinuous mesh coupling unit 15.

  That is, in the thermal analysis apparatus 100, the micro space region creation unit 11 defines and divides and defines an arbitrary space region including the space where the three-dimensional model to be analyzed exists into a micro hexahedral space region, and the physical property value determination unit 12 Thus, the physical property value of the micro hexahedral space region created by the micro space region creation unit 11 is determined, and the physical property values of a plurality of adjacent micro hexahedral space regions are the same by the micro space region redefinition unit 13. In this case, the plurality of minute hexahedral space regions are collectively redefined as one minute hexahedral space region, and redefined by the calculation space hexahedral mesh creating unit 14 by the minute space region redefining unit 13. A hexahedral mesh for calculation of the spatial region size of the micro hexahedral space region is created, and the calculation hexahedral mesh creation unit 14 uses the discontinuous mesh combination processing unit 15. For the calculated hexahedral mesh, the state variables of unconnected mesh nodes are mathematically averaged at nearby nodes, and further weighted according to the physical properties of the elements to be joined. The hexahedral mesh for continuity is subjected to a coupling process, and the thermal analysis processing unit 16 analyzes the analysis model indicated by the calculation hexahedral mesh subjected to the coupling process by the discontinuous mesh coupling processing unit 15. Do.

  In this thermal analysis apparatus 100, for example, a finite element method model, a finite volume method model, or a finite difference method is used based on the analysis model indicated by the hexahedral mesh for calculation subjected to the coupling process by the discontinuous mesh coupling unit 15. Analyze the temperature field of the mold using the model creation method.

  Since the outermost surface (outer wall surface) of the mold is exposed to the outside air, it is necessary to define the amount of heat (boundary condition) that is radiated to the outside air per hour, but it is usually used for the finite element method, etc. The pre-post processor can recognize and define a surface that is not connected to any element as an outer wall surface, and a surface of a continuous element is not an outer wall surface. In this example, when elements with different decision indices are adjacent, there is a part that does not share the node, so there is a possibility that a pre-post processor of the type that recognizes the outer wall in the conventional node sharing determination may be erroneously recognized. There is. For this reason, a method for discriminating the surface of the outer wall other than whether or not the node is shared is separately required. For example, after checking the existence of adjacent elements for 6 faces to determine whether there are adjacent faces, and comparing their own elements with the adjacent element's judgment index, if the numerical values are different, for example, the node is not shared However, there is a technique such as spitting out information that the plane is shared.

  Therefore, in the thermal analysis apparatus 100, the boundary condition setting unit 18 specifies the minute hexahedral space region created by the minute space region creating unit 11 based on the boundary surface information obtained by the boundary surface information calculation unit 17. It is instructed not to roughen the mesh by a certain distance or a certain mesh pitch from the boundary surface.

  When there is a discontinuous joint surface at the outermost surface portion, for example, as shown in FIG. 7, the mesh M1 created with the determination index [1] and the mesh M8 created with the determination index [8] are adjacent to each other, and the mesh M8 For the surface A, there is an adjacent slightly smaller mesh M1, and the heat transfer coefficient is adjusted by, for example, 3/4 times in this case. Therefore, it is desirable to cope with the information output form in consideration of the contact area between the adjacent outer walls. In addition, when the heat transfer coefficient is adjusted by 3/4 in this way, the analysis accuracy in the vicinity decreases, so if the prediction accuracy of the model surface part where the heat transfer coefficient must be defined is important, the surface All elements that are closest to and those that require accuracy are limited to a small determination index such as [1] or [8], and are discontinuous on the outer wall surface or parts where analysis accuracy is extremely important. It is desirable to have a function that prevents element coupling from occurring.

  For the analysis model created in this way, after assigning the material constants, heat load conditions, and heat transfer conditions necessary for the heat conduction analysis, the thermal analysis processing unit 16 performs calculations, and the resulting temperature gradient is calculated. Processed by the post-processing unit 50.

  Here, FIG. 8 shows an example in which the internal water-cooled piping of the mold is performed by thermal analysis using the thermal analysis apparatus 100. Many water pipes 150 are disposed in the mold 160 in multiple directions. In addition, the complicated product shape of the resin to be molded is also formed in the mold as a mold, so to draw these with 3D CAD at once with a commercially available automatic mesher, shorten the analysis calculation time (reducing the number of elements) Therefore, it is difficult to manually correct by chamfering unnecessary for analysis, deletion of small bosses and holes, and correction and deletion of minute surfaces caused by Boolean calculation errors when creating a model with 3D CAD Although a lot of labor is required, the thermal analysis apparatus 100 does not automatically determine whether or not a solid exists in each divided minute space, and does not define an element as a minute region. Since elements are defined after merging adjacent identical material regions, analysis calculations can be performed with a small number of elements, and manual analysis models can be greatly automated.

  When performing temperature analysis by performing element division as in the finite element method, the accuracy of the analysis is better for the part where the temperature gradient is large, with finer elements. Therefore, in the thermal analysis apparatus 100, analysis with a model once created by the mesh creation method as described above, and the calculation of a fine mesh by looking at the distribution gradient of the heat and stress is more accurate. If possible, the information to be refined is transmitted to the minute space region creation unit 11 again, the determination index is changed, the discontinuous part of the mesh is reconstructed, and the analysis model is created.

  That is, in the thermal analysis apparatus 100, the mesh refining determination unit 40 compares the thermal analysis solution obtained by the thermal analysis processing unit 16 with the size of the mesh, and determines whether there is a portion with a steep thermal gradient. Based on the determination result, the size of the minute hexahedron space region created by the minute space region creating unit 11 is controlled to reduce the size of the minute hexahedron space region at the portion where the thermal gradient is steep. .

  In the above description, the minute space region is compared with the adjacent minute space region, and the mesh M8 is created in which the comparison region to be largely grouped is the minute space region corresponding to eight, but (A), ( As shown in B) and (C), even if the mesh M2 having two minute space areas and the mesh M4 having four minute space areas are created, the same state on the discontinuous surface is obtained. Variables can be defined. By combining these, an efficient element number reduction model can be realized.

  In order to express the analysis model shape with hexahedral elements, it is necessary to determine the minimum hexahedral element size below the minimum size of the part to be expressed. Since the software of the volume method or the finite difference method can be used, it is not necessary to make all the hexahedrons similar. Therefore, for example, if the object to be finely defined is partially present and the location of the portion that should be expressed in fine hexahedron in advance and the location of the rough portion are known, as shown in FIG. Correspondingly, it is also possible to define a mesh that is dense and dense by changing the definition of the lengths of x, y, and z of the minute area for each part. As a result, the number of analysis elements can be further reduced, and the calculation speed can be increased.

  Further, in the thermal analysis apparatus 100, thermal analysis is performed with hexahedral elements. However, a defined area may be a combination of hexahedrons or a mixture of hexahedral elements by combining two pairs of tetrahedrons. It is.

  Furthermore, in the thermal analysis apparatus 100, all of the analysis systems are hexahedral elements. However, in particular, when considering flow in the piping portion, if there are surface irregularities, the fluid calculation becomes unstable. If the corner is actually R, a pentahedral element (triangular prism element) or a tetrahedral element (tetra element) may be partially added. In the fluid calculation part, in order to improve the accuracy of fluid calculation, it is effective to create a mesh after fixing the determination index so that discontinuous joining is not allowed only in the mesh part defined by the liquid.

  The functions of the thermal analysis apparatus 100 as described above can be realized by executing various processes according to a thermal analysis program on a personal computer having a configuration as shown in FIG. 11, for example.

  A thermal analysis apparatus 100 shown in FIG. 11 is a personal computer, and includes a CPU 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an HDD 104, a graphic processing unit 105, an input I / F (Interface) 106, and the like. These are connected to each other via a bus 107.

  Here, the CPU 101 controls each unit according to a program stored in the HDD 104. In addition, various calculations described above are performed.

  The ROM 102 stores basic programs and data executed by the CPU 101.

  The RAM 103 temporarily stores programs being executed by the CPU 101 and data being calculated. Further, the material table described above may be temporarily stored.

  The HDD 104 stores an OS executed by the CPU 101, an application program for performing automatic mesh generation processing as described above, ECAD data, and the like.

  A display device 105 a such as a display is connected to the graphic processing unit 105, and an image is displayed on the screen of the display device 105 a in accordance with a drawing command from the CPU 101.

  A mouse 106 a and a keyboard 106 b are connected to the input I / F 106, and information input by the user is received and transmitted to the CPU 101 via the bus 107.

  Here, the mesh generation processing unit 10 and the discontinuous mesh unit combination calculation unit 30 in FIG. 1 are realized by executing a mesh generation processing program stored in the HDD 104 under the control of the CPU 101. The input / output data processing unit 20 corresponds to the input I / F 106 and the graphic processing unit 105, and the storage unit 40 corresponds to the ROM 102, RAM 103, or HDD 104.

  Although not shown in the figure, a communication interface may be provided to connect to a network and input CAD data or the like from a database server or the like.

  In the thermal analysis apparatus 100, the CPU 101 executes various processes PR1 to PR6 shown in the flowchart of FIG. 12 according to the thermal analysis program.

  That is, in the minute space region creation process PR1, an arbitrary space region including the space in which the three-dimensional model to be analyzed exists is divided and defined as a minute hexahedral space region.

  In the physical property value determination process PR2, the physical property value of the minute hexahedral space region created by the minute space region creating unit is determined.

  In the minute space region redefinition process PR3, when a plurality of adjacent minute hexahedron space regions have the same physical property value, the plurality of minute hexahedron space regions are collectively redefined as one minute hexahedron space region. .

  In the discontinuous mesh connection processing PR4, the state variables of unconnected mesh nodes are mathematically averaged at nearby nodes, and further weighted according to the physical properties of the joined elements to be averaged. A process for providing continuity is performed.

  In the calculation hexahedral mesh creating process PR5, a calculation hexahedral mesh redefined in each space area is created by the space area size defined by the minute space area redefinition process PR3.

  In the thermal analysis process PR5, the analysis model indicated by the calculation hexahedral mesh created by the calculation hexahedral mesh creation process is analyzed.

  As described above, the functions of the thermal analysis apparatus 100 as described above are realized by executing the various processes PR1 to PR6 shown in the flowchart of FIG. 12 according to the thermal analysis program on the personal computer having the configuration shown in FIG. can do. In that case, a thermal analysis program describing the processing contents of the functions that the thermal analysis apparatus 100 should have is provided. By executing the thermal analysis program on a computer, the functions of the thermal analysis apparatus 100 are realized on the computer. The thermal analysis program describing the processing content can be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory. Examples of the magnetic recording device include an HDD, a flexible disk (FD), and a magnetic tape. Examples of the optical disc include a DVD (Digital Versatile Disc), a DVD-RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only Memory), and a CD-R (Recordable) / RW (ReWritable). Magneto-optical recording media include MO (Magneto-Optical disc).

  When this thermal analysis program is distributed, for example, portable recording media such as DVDs and CD-ROMs on which the program is recorded are sold. It is also possible to store a thermal analysis program in a storage device of a server computer and transfer the program from the server computer to another computer via a network.

  A computer that executes a thermal analysis program stores, for example, a program recorded on a portable recording medium or a program transferred from a server computer in its own storage device. Then, the computer reads the program from its own storage device and executes processing according to the thermal analysis program. The computer can also read the program directly from the portable recording medium and execute processing according to the program. Further, each time the program is transferred from the server computer, the computer can sequentially execute processing according to the received program.

It is a block diagram which shows the structure of the thermal-analysis apparatus to which this invention is applied. It is a figure which shows typically the micro hexahedral space area | region of the fixed size defined by the micro space area | region preparation part in the said thermal analysis apparatus. It is a figure which shows typically the processing unit of the primary merge determination in the primary merge determination part with which the micro space area | region redefinition part of the said thermal analyzer was equipped. It is a figure which shows typically the mode of the primary merge determination in the said primary merge determination part. It is a figure which shows typically the mode of the primary merge determination in the said primary merge determination part. It is a figure which shows typically the mode of the joint process by the discontinuous mesh joint process part of the said thermal analysis apparatus. It is a figure which shows typically the example which adjusts a heat transfer coefficient when there exists a discontinuous junction surface in the outermost surface part. It is a figure which shows typically the example which performed thermal analysis with the said thermal-analysis apparatus and performed the internal water cooling piping of the metal mold | die. It is a figure which shows typically the creation example of the mesh made into the minute space area for 2 pieces, and the mesh made into the minute space area for 4 pieces. It is a figure which shows typically the example of mesh creation when the object which wants to define finely exists partially, and the location which should be expressed with a fine hexahedron beforehand and the location where the rough part is good are known. It is a block diagram which shows the structure of the personal computer which performs the various processes which implement | achieve the function of a thermal analysis apparatus. It is a flowchart which shows the execution procedure of the various processes which implement | achieve the function of a thermal-analysis apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Mesh creation process part, 11 Minute space area creation part, 12 Physical property value determination part, 13 Minute space area redefinition part, 14 Hexahedral mesh creation part for calculation, 15 Discontinuous mesh connection part, 16 Thermal analysis process part, 20 Input / output data processing unit, 30 discontinuous mesh unit combination calculation unit, 40 mesh re-refining determination unit, 50 storage unit, 60 post-processing unit, 100 thermal analysis device, 120 conversion region, 130, 130 (000), 130 ( 100), ..., 130 (111), 130 (222), 130 (322), ..., 130 (333) Micro hexahedral space region

Claims (6)

A thermal analysis apparatus for performing thermal analysis by creating a mesh for calculation of a finite element method, a finite volume method or a finite difference method,
A micro space region creation unit that divides and defines an arbitrary space region including a space where the three-dimensional model to be analyzed exists into a micro hexahedral space region;
A physical property value determining unit that determines the physical property value of the micro hexahedral space region created by the micro space region creating unit;
A micro space region redefinition unit that redefines the plurality of micro hexahedron space regions as a single micro hexahedron space region when physical property values of a plurality of adjacent micro hexahedron space regions are the same;
A calculation hexahedral mesh creating unit for creating a hexahedral mesh for calculation of a spatial region size of a micro hexahedral space region redefined by the micro space region redefinition unit,
For the calculation hexahedron mesh created by the calculation hexahedron mesh creation unit, the state variables of unconnected mesh nodes are mathematically averaged at nearby nodes, and further weighted according to the physical properties of the joined elements. A discontinuous mesh combination processing unit for performing a combination process to give continuity to the calculation hexahedral mesh,
A thermal analysis processing unit, comprising: a thermal analysis processing unit that performs analysis on an analysis model indicated by a hexahedral mesh for calculation subjected to coupling processing by the discontinuous mesh coupling processing unit. The minute space region redefinition unit includes a double space region including a reference space region expanded in any one of the X, Y, and Z directions, or any two of the X, Y, and Z directions. Check for every four times the space region including the reference space region expanded in the direction or every eight times the space region including the reference space region expanded in the three directions in the X, Y, and Z directions. The thermal analysis apparatus according to claim 1, wherein the small hexahedral space regions are bundled and redefined as a large space region. Comparing the size of the mesh with the solution of the thermal analysis obtained by the thermal analysis processing unit, and equipped with a mesh refining determination unit that determines the presence or absence of a portion with a sharp thermal gradient
Based on the determination result by the mesh re-miniaturization determining unit, the size of the micro hexahedral space region created by the micro space region creating unit is controlled, and the size of the micro hexahedral space region of the portion where the thermal gradient is steep The thermal analysis apparatus according to claim 1, wherein: The thermal analysis apparatus according to claim 1, further comprising a boundary condition setting unit that instructs not to coarse the mesh by a predetermined distance or a predetermined mesh pitch from the specified boundary surface. A thermal analysis method for performing thermal analysis by creating a calculation mesh for a finite element method, a finite volume method or a finite difference method,
An arbitrary spatial region that covers the space in which the three-dimensional model to be analyzed exists is defined as being divided into micro hexahedral space regions,
Determine the physical property value of the micro hexahedral space region,
When physical property values of a plurality of adjacent micro hexahedral space regions are the same, the plurality of micro hexahedral space regions are collectively redefined as one micro hexahedral space region,
Create a hexahedral mesh for calculating the spatial area size of the redefined micro hexahedral space area,
For the created hexahedral mesh for calculation, the above calculation is performed by mathematically averaging the state variables of the unjoined mesh nodes at neighboring nodes and then averaging by averaging according to the physical properties of the joined elements. Discontinuous mesh combination processing for performing continuity on the hexahedral mesh for use,
The thermal analysis method characterized by analyzing about the analysis model shown with the calculation hexahedral mesh in which the said discontinuous mesh coupling | bonding process was performed. A thermal analysis processing program for creating a computational mesh for a finite element method or a finite volume method or a finite difference method and performing thermal analysis by a computer,
A minute space region creation process for dividing and defining an arbitrary space region including the space in which the three-dimensional model to be analyzed exists into a minute hexahedral space region;
A physical property value determining process for determining a physical property value of the micro hexahedral space region created by the micro space region creating unit;
A micro space region redefinition process for redefining the plurality of micro hexahedron space regions as a single micro hexahedron space region when physical properties of adjacent micro hexahedron space regions are the same;
A calculation hexahedral mesh creation process for creating a hexahedral mesh for calculation of the spatial area size of the micro hexahedral space area redefined by the micro space area redefinition process;
For the created hexahedral mesh for calculation, the above calculation is performed by mathematically averaging the state variables of the unjoined mesh nodes at neighboring nodes and then averaging by averaging according to the physical properties of the joined elements. Discontinuous mesh combination processing for performing continuity on the hexahedral mesh for use,
The thermal analysis processing program which performs by computer the thermal analysis process which analyzes about the analysis model shown with the hexahedral mesh for calculation to which the said discontinuous mesh coupling | bonding process was performed.

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