JP2009026085A - Thermal analysis apparatus, thermal analysis method, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal analysis apparatus capable of executing highly accurate radiation calculation within a short calculation time, a thermal analysis method, a program, and a recording medium. <P>SOLUTION: A surface element object area calculation part 14 calculates an object area of surface elements in each component on the basis of the heating value of the component composing an analysis target. A surface element model generation part 15 combines surface polygons of a polyhedron of a three-dimensional element model generated by a three-dimensional element model generation part 13 to generate a surface element model composed of surface elements more than the object area of the surface elements in each component which is calculated by the surface element object area calculation part 14. A thermal analysis part 16 applies thermal analysis based on numerical analysis such as a finite element method, a finite difference method or a finite volume method to the surface element model generated by the surface element model generation part 15. An output part 17 outputs analysis results, e.g. values such as temperatures or heat flux of respective portions, which are obtained by the thermal analysis in the thermal analysis part 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal analysis apparatus, a thermal analysis method, a program, and a recording medium that can perform thermal analysis using a computer in consideration of the influence of thermal radiation, and in particular, when a heating element is present in an analysis object. The present invention relates to a thermal analysis apparatus, a thermal analysis method, a program, and a recording medium relating to generation of a radiation calculation surface element that is a unit of calculation of radiation heat transfer.

  Thermal evaluation of electronic equipment, manufacturing equipment, buildings, etc. is widely performed in industry by thermal analysis using numerical analysis methods such as finite volume method, finite element method, or finite difference method using a computer. . Thermal analysis that considers all three forms of heat transfer, namely conduction, convection, and radiation or radiation, is also widely performed.

  In the thermal analysis, first, for calculation of conduction and convection, a three-dimensional calculation target region is divided into sufficiently small three-dimensional elements, for example, hexahedral elements or tetrahedral elements, and a relational expression between adjacent elements is determined. Then, the entire calculation region is solved using the relational equations defined between all the elements as simultaneous equations. For example, when the entire region is divided into checkered hexahedral elements and a relational expression is defined between adjacent elements in contact with each other, the number of adjacent elements per element is + X, −X when considered in the XYZ coordinate system. , + Y, -Y, + Z, and -Z directions in total, and there are a total of 6 directions, and if the total number of elements is N, the coefficient representing the strength of the degree of influence between adjacent elements is 6N in total.

The governing equation of radiation is not established only between adjacent surface elements, but is established between all elements at positions where radiant heat can be transferred, that is, positions that can be seen. For example, the amount of heat Q _AB transferred from the element A to the element B can be calculated from the equation (6).

Here, σ is a Stefan Boltzmann constant, and its value is 5.67e ⁻⁸ (W / m ² / K ⁴ ). area of epsilon _A is emissivity of the element A, the emissivity of the epsilon _B elements B, _{T a} is the absolute temperature of the element A (K), _{T b} is the element B absolute temperature (K), and _{S A} are elements A (M ² ). F _AB is a radiation form factor and can be calculated from equation (7).

Here, dS _A is a minute area on the element A, dS _B is a minute area on the element B, φ _A is a zenith angle when the minute area dS _B is seen from the minute area dS _A , and φ _B is a minute area from the minute area dS _B The zenith angle when dS _A is viewed, and r is the distance between the minute area dS _A and the minute area dS _B.

  In order to calculate radiation, the surface of the solid to be radiated is divided into two-dimensional surface elements. The governing equation of radiation does not hold only between adjacent surface elements as described above, but is an expression that holds between all elements that can receive and receive radiant heat, that is, positions that can be seen. Therefore, when considering the transfer of heat between all elements with N as the total number of elements, the coefficient representing the degree of influence of radiation between elements is N for one element, that is, the square of N in total. Compared with the number of conduction and convection influence coefficients of 6N, the order of N is one greater.

The number N of radiation calculation surface elements may exceed tens of thousands to hundreds of thousands when the dimensions of the radiation calculation surface elements are the same as those of the three-dimensional elements for conduction and convection calculation. In this case, the number of radiation form factors F _AB is several hundreds of millions to several billions, and the amount of information to be processed and the calculation time are enormous. Therefore, in thermal analysis with radiation, the surface of a three-dimensional element is generally divided instead of using each two-dimensional polygon obtained by dividing the surface of the three-dimensional element as a surface element for radiation calculation. A combination of a plurality of two-dimensional polygons is processed as one radiation calculation surface element.

  As a first conventional technique, there is a form factor calculation device capable of executing a form factor calculation at high speed. The form factor is a factor used in a thermal simulation at a high temperature where radiation is dominant, and energy emitted from one element of a set of elements reaches another element of the set of elements. Represents a percentage. This form factor computing device subdivides a quadrilateral element having a larger area than the distance when another quadrilateral element relative to the one quadrilateral element is larger than the distance between the two quadrilateral elements. . For example, when radiant heat transfer from the quadrangular element A to the quadrangular element B is considered, the quadrangular element A is subdivided when the area of the quadrangular element A is larger than the distance between the quadrangular element A and the quadrangular element B. (For example, refer to Patent Document 1).

  As a second conventional technique, there is a mesh subdivision method used when calculating the illuminance of a surface by computer graphics. In this subdivision method, the surface irradiated with light is divided into triangular meshes, and the difference between the illuminance calculated for one mesh and the illuminance of the mesh further subdivided by interpolation is determined according to a predetermined reference. If it is greater than or equal to the value, the mesh is subdivided. For example, the illuminance calculated with the coarsely divided mesh A is compared with the illuminance calculated with the mesh B obtained by subdividing the mesh A, and if there is a difference between the two illuminances, the mesh A is subdivided (for example, non- Patent Document 1).

JP 2002-109562 A Jaroslav Kr iv 疣 ek, two others, “Adaptive Mesh Subdivision for Precomputed Radiance Transfer”, Spring Conference on Computer Graphics, April 2004

  In radiation calculation, the calculation of the form factor is very expensive, and a large amount of storage capacity is required to store the form factor data, so the number of elements for calculating the form factor is the minimum to ensure accuracy. If it is not limited to the necessary number, calculation efficiency will deteriorate.

  For objects that generate heat, a large temperature difference occurs depending on the location of the surface of the object.In other words, the temperature distribution is not uniform. It is necessary to finely divide the elements for calculation.

  The first conventional technique is a division method that does not take into consideration the presence or absence of heat generation and the amount of heat generation, and unless it is divided into fine elements, radiation calculation cannot be executed with sufficient accuracy. However, if the elements are made finer, the number of elements increases, so there is a problem that the calculation time becomes longer.

  The second conventional technique further divides based on the result calculated by dividing into coarse elements. However, in the thermofluid analysis, there is a problem that if a portion where the change is rapid is further subdivided based on the temperature distribution once calculated, the processing time becomes enormous because one calculation time is long. In addition, the computational elements are also used to calculate the effects of conduction and convection, and it is difficult to freely subdivide only for radiation.

  An object of the present invention is to provide a thermal analysis apparatus, a thermal analysis method, a program, and a recording medium that can execute highly accurate radiation calculation in a short calculation time.

The present invention comprises a storage means for storing shape information representing the shapes of a plurality of parts constituting the analysis object;
Three-dimensional element model generation means for generating a three-dimensional element model composed of a three-dimensional polyhedron by dividing the shape of the part indicated by the shape information stored in the storage means for each part;
A surface element target area calculating means for calculating a target area of a surface element composed of a portion of a surface constituting a surface of the component for each component by a predetermined calculation formula for calculating the target area;
The target area calculated for each part by the surface element target area calculating means by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated by the three-dimensional element model generating means A surface element model generating means for generating a surface element model composed of surface elements of the above area;
The thermal analysis apparatus includes thermal analysis means for calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated by the surface element model generation means.

According to the present invention, the storage means further stores heat generation information indicating the heat generation amount of the plurality of parts,
The surface element model generation means is configured such that the heat generation amount indicated by the heat generation information stored in the storage means is less than the heat generation amount of the first component. Of the plurality of parts, the area is less than the maximum area of the surface element of the second part.

According to the present invention, the storage means further stores heat generation information indicating the heat generation amount of the plurality of parts,
The surface element model generation means calculates the area of the surface element of the first part whose heat generation amount indicated by the heat generation information stored in the storage means among the plurality of parts is not zero. The amount of heat generated by the heat generation information stored in the storage means is zero or less than the area of the surface element of the second component having zero.

According to the present invention, the storage means further stores heat generation information indicating the heat generation amount of the plurality of parts,
The surface element model generating means sets at least four surface elements to have a surface with the largest area among the surfaces constituting the surface of the component whose heat generation amount indicated by the heat generation information stored in the storage means is not zero. Features.

Further, according to the present invention, the storage means further stores heat density information representing heat density of the plurality of parts,
The surface element model generation means has at least four surfaces having the largest area among the surfaces constituting the surface of the component having a heat generation density indicated by the heat generation density information stored in the storage device equal to or higher than a predetermined reference heat generation density. It is a surface element.

Further, in the present invention, the storage means further stores thermal conductivity information representing the thermal conductivity of the plurality of components,
The surface element model generation means has a surface with the largest area among the surfaces constituting the surface of the component having a thermal conductivity indicated by the thermal conductivity information stored in the storage means equal to or higher than a predetermined reference thermal conductivity. It is characterized by having at least four surface elements.

Further, according to the present invention, the storage means includes volume information indicating the volume of the plurality of components, heat generation information indicating the heat generation amount of the plurality of components, and a predetermined reference area for calculating a target area of the surface element. , Further storing surface element control information representing a predetermined correction coefficient and a constant to be determined;
The predetermined calculation formula is such that the volume indicated by the volume information stored in the storage means is V, the heat generation amount indicated by the heat generation amount information stored in the storage means is Q, and the surface element control information stored in the storage means. The predetermined reference area indicated by is Sk, and the predetermined correction coefficient indicated by the surface element control information stored in the storage means is 瘁 A and the constant to be determined indicated by the surface element control information stored in the storage means is a. When the surface area target area S for each part is
S = min (Sk, (Sk / (α × Q / V) ^a ))
It is characterized by being.

According to the present invention, the storage means includes volume information indicating the volume of the plurality of components, heat generation information indicating the heat generation amount of the plurality of components, and thermal conductivity information indicating the thermal conductivity of the plurality of components. And a predetermined reference area for calculating the target area of the surface element, a predetermined correction coefficient, and surface element control information representing a constant to be determined,
The predetermined calculation formula is such that the volume indicated by the volume information stored in the storage means is V, the heat generation amount indicated by the heat generation amount information stored in the storage means is Q, and the thermal conductivity information stored in the storage means. D, the predetermined reference area indicated by the surface element control information stored in the storage means Sk, and the predetermined correction coefficient indicated by the surface element control information stored in the storage means 竅 A When the constants to be predetermined indicated by the surface element control information stored in the means are b, c and d, the target area S of the surface element for each part is:
S = min (Sk, (Sk / (β × Q b / V c / D d)))
It is characterized by being.

The present invention also includes a three-dimensional polyhedron by dividing the shape of the part indicated by the shape information stored in the storage device that stores shape information representing the shape of a plurality of parts constituting the analysis object into parts. A three-dimensional element model generation step for generating a three-dimensional element model;
A surface element target area calculation step for calculating a target area of a surface element composed of a part of a surface constituting the surface of the part for each part by a predetermined calculation formula for calculating the target area;
The target area calculated for each part in the surface element target area calculation step by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated in the three-dimensional element model generation step A surface element model generation step for generating a surface element model composed of surface elements of the above area;
A thermal analysis method comprising: a thermal analysis step of calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated in the surface element model generation step.

The present invention also includes a three-dimensional polyhedron by dividing the shape of the part indicated by the shape information stored in the storage device that stores shape information representing the shape of a plurality of parts constituting the analysis object into parts. A three-dimensional element model generation step for generating a three-dimensional element model;
A surface element target area calculation step for calculating a target area of a surface element composed of a part of a surface constituting the surface of the part for each part by a predetermined calculation formula for calculating the target area;
The target area calculated for each part in the surface element target area calculation step by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated in the three-dimensional element model generation step A surface element model generation step for generating a surface element model composed of surface elements of the above area;
This is a program for causing a computer to execute a thermal analysis step of calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated in the surface element model generation step.
The present invention is also a computer-readable recording medium on which the program is recorded.

  According to the present invention, the storage means stores shape information representing the shapes of a plurality of parts constituting the analysis object, and the three-dimensional element model generation means indicates the shape of the part indicated by the shape information stored in the storage means. Is divided into parts, a three-dimensional element model consisting of a three-dimensional polyhedron is generated, and the target area of the surface element consisting of the surface parts constituting the surface of the part is calculated by the surface element target area calculation means It is calculated for each part by a predetermined calculation formula for calculating.

  Then, by the surface element model generation means, the adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated by the three-dimensional element model generation means are combined, and the surface element target area calculation means A surface element model consisting of surface elements with an area equal to or larger than the target area calculated for each part is generated, and the surface element model generated by the surface element model generation means is generated from the surface of each part by the thermal analysis means. Thermal analysis is performed by calculating the thermal radiation.

  Therefore, it is possible to avoid making the surface element unnecessarily fine by setting the surface element to a surface element larger than the target area calculated for each part by a predetermined calculation formula. A highly accurate radiation calculation can be executed.

  Further, according to the present invention, in the three-dimensional element model generation step, the shape of the part indicated by the shape information stored in the storage device that stores the shape information indicating the shape of the plurality of parts constituting the analysis object is determined for each part. A three-dimensional element model composed of a three-dimensional polyhedron is generated by division, and in the surface element target area calculation step, a target area of a surface element formed of a portion of a surface constituting the surface of the part is calculated. The calculation is performed for each part using a predetermined calculation formula.

  Then, in the surface element model generation step, among the faces of the polyhedron of the three-dimensional element model generated in the three-dimensional element model generation step, adjacent surfaces exposed on the surface of the part are combined, and a surface element target area calculation step In the thermal analysis process, a surface element model is created from the surface of each part with respect to the surface element model generated in the surface element model generation process. The thermal radiation is calculated and thermal analysis is performed.

  Therefore, if the thermal analysis method according to the present invention is used, it is possible to make the surface element finer than necessary by making the surface element larger than the target area calculated for each part by a predetermined calculation formula for the size of the surface element. Since this can be avoided, highly accurate radiation calculation can be executed in a short calculation time.

Further, according to the present invention, the three-dimensional polyhedron is obtained by dividing the shape of the part indicated by the shape information stored in the storage device that stores the shape information representing the shape of the plurality of parts constituting the analysis object into parts. A three-dimensional element model generation step for generating a three-dimensional element model comprising:
A surface element target area calculation step for calculating a target area of a surface element composed of a part of a surface constituting the surface of the part for each part by a predetermined calculation formula for calculating the target area;
The target area calculated for each part in the surface element target area calculation step by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated in the three-dimensional element model generation step A surface element model generation step for generating a surface element model composed of surface elements of the above area;
Provided as a program for causing a computer to execute a thermal analysis process for calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated in the surface element model generation process it can.

  The present invention can also be provided as a computer-readable recording medium on which the program is recorded.

  FIG. 1 is a block diagram showing a configuration of a thermal analysis apparatus 1 according to an embodiment of the present invention. The thermal analysis method according to the present invention is processed by the thermal analysis apparatus 1.

  The thermal analysis apparatus 1 includes a control unit 10, a shape information input unit 11, a material property value input unit 12, a three-dimensional element model generation unit 13, a surface element target area calculation unit 14, a surface element model generation unit 15, and a thermal analysis unit 16. , An output unit 17, a CAD (Computer Aided Design) information database D1, a material information database D2, a surface element control information database D3, a three-dimensional element information database D4, a surface element information database D5, and an output result database D6.

  The thermal analysis device 1 includes, for example, an input device such as a keyboard and a mouse, a control device including a CPU (Central Processing Unit) and an I / O (Input / Output) interface connected to the CPU, and a semiconductor that stores programs and data. A storage device such as a memory and a hard disk device, a display device such as a CRT (Cathode Ray Tube) and an LCD (Liquid Crystal Display), and an output device including a printing device such as a printer.

  Data stored in the storage device includes data of a CAD information database D1, a material information database D2, a surface element control information database D3, a three-dimensional element information database D4, a surface element information database D5, and an output result database D6.

  The CPU executes a program stored in the storage device to thereby execute a control unit 10, a shape information input unit 11, a material property value input unit 12, a three-dimensional element model generation unit 13, a surface element target area calculation unit 14, a surface The functions of the element model generation unit 15, the thermal analysis unit 16, and the output unit 17 are realized. The number of CPUs included in the control device is not limited to one, and a configuration including a plurality of CPUs may enable parallel calculation and have an excellent calculation speed.

  The devices included in the thermal analysis device 1 are not limited to these, and may include a communication device that transmits / receives information to / from other devices connected to a communication line such as a LAN (Local Area Network). The communication device may receive information created by the CAD device, for example, from a CAD device connected to the LAN, or the information may be transmitted and stored in a storage device connected to the LAN. The apparatus included in the thermal analysis apparatus 1 may be a generally known apparatus, and detailed description thereof is omitted.

  The CAD information database D <b> 1 that is a storage unit is a database that stores CAD information input by the shape information input unit 11. The CAD information represents information about each part included in the analysis target, for example, shape information indicating the shape of the part, material type information indicating the material type of the part, heat generation amount information indicating the heat generation amount of the part, and volume of the part. This is volume information, position information indicating the position of the component, and information indicating the shape of the analysis target area. The material information database D <b> 2 that is a storage unit is a database that stores material information input by the material property value input unit 12. The material information is information representing the material property value for each material type, for example, heat conductivity information representing heat conductivity, heat generation density information representing heat generation density, and specific heat information representing specific heat.

  The surface element control information database D3, which is a storage means, is a database that stores surface element control information. The surface element control information is information representing a reference heat generation density, a reference heat conductivity, a reference area Sk of the surface element, power constants a, b and d, correction coefficients α and β, and the like. The three-dimensional element information database D4 stores three-dimensional element information representing the three-dimensional element model generated by the three-dimensional element model generation unit 13.

  The surface element information database D5 stores target area information representing the target area of the radiation calculation surface element for each component and surface element information representing a surface element model including the radiation calculation surface elements. The surface element for radiation calculation is a part of the surface that constitutes the surface of the component, and is used for performing a thermal analysis that takes into account thermal radiation from the surface of each component. Hereinafter, the surface element for radiation calculation is also simply referred to as “surface element”. The output result database D6 stores output information obtained by the output unit 17 outputting the analysis result analyzed by the thermal analysis unit 14.

  The control unit 10 includes a shape information input unit 11, a material property value input unit 12, a three-dimensional element model generation unit 13, a surface element target area calculation unit 14, a surface element model generation unit 15, a thermal analysis unit 16, an output unit 17, The CAD information database D1, the material information database D2, the surface element control information database D3, the three-dimensional element information database D4, the surface element information database D5, and the output result database D6 are controlled, and information exchange between them is also controlled.

  The shape information input unit 11 inputs CAD information and stores the input CAD information in the CAD information database D1. The material property value input unit 12 inputs material information and stores the input material information in the material information database D2.

  The three-dimensional element model generation unit 13 which is a three-dimensional element model generation unit refers to the CAD information stored in the CAD information database D1, and changes the shape of the parts constituting the analysis target into a three-dimensional polyhedron. Split into elements. Then, a three-dimensional element model composed of the divided three-dimensional elements is generated, and the three-dimensional element information representing the generated three-dimensional element model is stored in the three-dimensional element information database D4. The shape of the polyhedron of the three-dimensional element is generally a tetrahedron, a pentahedron such as a triangular prism, and a hexahedron, but any shape other than these can be used as long as the shape can be processed by the thermal analysis unit 16. Good.

  The surface element target area calculation unit 14 which is a surface element target area calculation means is stored in the CAD information stored in the CAD information database D1, the material information stored in the material information database D2, and the surface element control information database D3. With reference to the surface element control information, the target area of the surface element is calculated, and the target area information representing the calculated target area is stored in the surface element information database D5.

FIG. 2 is a diagram for explaining radiant heat transfer. Consider the amount of radiation heat transfer Q _AB from the heat generating surface A31 shown in FIG. 2 to the surface B32 of any shape that does not generate heat that faces the surface A31.

  For simplicity of explanation, the surface A31 is a square surface on the XY plane of the XYZ coordinate system, and one set of parallel sides of the square is parallel to the X axis and another parallel surface orthogonal to these sides. One set of sides is parallel to the Y axis. Further, assume that the position of one vertex of the surface A31 is XY coordinates (0, 0), and the length of one side is d.

  The temperature gradient of the surface A31 is “2a” in the X-axis direction and “0” in the Y-axis direction. The surface B32 has a uniform temperature in the surface. Assuming that the temperature at the position of X = 0 on the surface A31 is Ta0, the temperature Ta at the position of the coordinates (x, y) on the surface A31 is Ta0 + 2ax. For example, the temperature in the minute region R0 where X = 0 is Ta0, the temperature in the minute region R1 where X = d / 2 is Ta0 + a, and the temperature in the minute region R2 where X = d is Ta0 + 2a. is there.

The amount of radiant heat transfer Q _AB from any one point on the surface A31 to the surface B32 is expressed by the above-described equations (6) to (1).

Here, σ is a Stefan Boltzmann constant, and its value is 5.67e ⁻⁸ (W / m ² / K ⁴ ). emissivity of epsilon _A elements A, emissivity of epsilon _B elements B, _{T a} is the absolute temperature of the element A (K), _{T b} is the element B absolute temperature (K), and _{S A} are elements A clogging surface It is the area (m ² ) of A31. F _AB is a radiation form factor and can be calculated from the above-described equation (7). For example, in the case of the two surfaces Sa and Sb, the distance between the two surfaces Sa and Sb is sufficiently large compared to the size of the two surfaces Sa and Sb, and the two surfaces Sa and Sb are substantially flat. The radiation form factor F _AB can be regarded as a substantially constant.

Here, regarding the radiant heat transfer amount Q _AB , the difference between the case where the temperature gradient in the X-axis direction is considered and the case where it is ignored is defined as ΔQ, and the influence of the temperature gradient on ΔQ is considered. In consideration of the temperature gradient, the temperature Ta of X = x on the surface A31 is Ta0 + 2ax. When the temperature gradient is ignored, the temperature Ta is uniformly Ta0 in the plane A31.

and

Defined as
ΔQ / dxdy = K × ((Ta0 + 2ax) ⁴ −Ta0 ⁴ )
It becomes. If this is transformed,
ΔQ / dxdy = K × (4 × 2ax × Ta0 ³ +6 (2ax) ² × Ta0 ²
+4 (2ax) ³ × Ta0 + (2ax) ⁴ )
= K × (8ax × Ta0 ³ + 24 × a ² × x ² × Ta0 ²
+ 16 × a ³ × x ³ × Ta0 + 2 × a ⁴ × x ⁴ )
It becomes. If this is integrated with x,
ΔQ / dy = K × (4a × x ² × Tao ³ + 8 × a ² × x ³ × Ta0 ²
+ 4 × a ⁴ × x ³ × Ta0 + 2/5 × a ⁵ × x ⁴ )
It becomes. If x is integrated between 0 and d,
ΔQ / dy = K × (4a × d ² × Tao ³ + 8 × a ² × d ³ × Ta0 ²
+ 4 × a ⁴ × d ³ × Ta0 + 2/5 × a ⁵ × d ⁴ )
It becomes. Furthermore, if y is integrated between 0 and d,
ΔQ = K × (4a × d ³ × Tao ³ + 8 × a ² × d ⁴ × Ta0 ²
+ 4 × a ⁵ × d ³ × Ta0 + 2/5 × a ⁵ × d ⁶ )
It becomes. Here, in a general heat problem at a room temperature or higher that is not under an extremely low temperature, a × d is at most about 10 degrees Celsius, whereas Ta0 is at least 300 degrees Celsius or more. The first term in parentheses may be approximated to 4a × d ³ × Ta0 ³
ΔQ≈K × 2a × d ³ × Ta0 ³
And can be approximated. In other words, it can be seen that the error in the amount of radiant heat transfer caused by ignoring the gradient of the surface temperature within one surface element is proportional to the temperature gradient 2a. Further, it can be seen that the error in the amount of radiant heat transfer is proportional to the cube of the size d of the radiating surface element.

  In a heat generating component in a heat-balanced state, the amount of heat generated by the component is equal to the total amount of heat passing through the closed curved surface containing the component. Therefore, when the surface area of the closed curved surface containing the heat-generating component in the heat-balanced state is 1 / n times, the unit area passing through the closed surface with the surface area being 1 / n times and the amount of heat per unit time are n times. In order to increase the amount of heat passing per unit time and unit area by n times, the thermal conductivity or the temperature gradient in the direction orthogonal to the closed curved surface must be n times.

  That is, since the temperature gradient on the surface of the component is considered to be proportional to the temperature gradient in the direction perpendicular to the surface, the temperature gradient on the surface of the component is inversely proportional to the thermal conductivity of the component and inversely proportional to the surface area of the component. It can be seen that the radiant heat transfer error is proportional to the calorific value of the component, inversely proportional to the surface area of the component, inversely proportional to the thermal conductivity of the component, and further proportional to the cube of the size of the surface element. In order to minimize the total radiation conduction error while keeping the total number of surface elements constant, the area of each surface element is adjusted so that the error ΔQ of the radiation heat transfer amount generated for each surface element is constant. do it.

ΔQ ∝ (heat generation amount of parts) × (surface element size) ³
/ ((Component thermal conductivity) × (part surface area))
Therefore, the size of the surface element that makes ΔQ constant is
Size of surface element ∝ ((Thermal conductivity of component) x (Surface area of component)
/ (Heat generation amount of parts)) ^1/3
It is requested from. If the area of the surface element is the square of the size of the surface element and the surface area of the part is the square of the size of the part,
Area of surface element ∝ (Heat generation amount of component) ^-2/3 x (Thermal conductivity of component) ^2/3
× (Part size) ^4/3
It becomes. Furthermore, if the volume of the component is the cube of the size of the component,
Area of surface element ∝ (Heat generation amount of component) ^-2/3 x (Thermal conductivity of component) ^2/3
× (Part volume) ^4/9
It can also be said that there is a negative correlation with the heat generation amount of the component, and if the heat generation amount is large, the surface element should be small. There is a positive correlation between the thermal conductivity of the component or the volume of the component, and it can be said that the surface element should be large if the thermal conductivity or volume is large.

The standard for setting the reference area Sk of the surface element is about 1/200 to 1/1000 of the typical area of the analysis object. For example, if the outer dimension of the object to be analyzed is a rectangular parallelepiped shape having a size of 50 mm × 200 mm × 300 mm, the representative area is 200 mm × 300 mm = 60000 mm ² on the basis of the maximum area surface. appropriate ^value, a 60mm ² ~300mm 2.

The setting criterion for the correction coefficient α is the reciprocal of a value that assumes that “heat generation density = heat generation amount / volume” is significantly large in the component of the analysis object. For example, if there are 100 heat generating parts with dimensions of 20 mm × 20 mm × 1 mm in the analysis object, 20 of the 100 heat generation amounts are 0.4 W or more, and the remaining 80 heat generation amounts are 0.1 W or less. Then, the threshold value of a significantly large heat generation density should be considered as any value between 0.1 W / (20 mm × 20 mm × 1 mm) and 0.4 W / (20 mm × 20 mm × 1 mm). Therefore, the ^{value, 0.00025W / mm 3 ~0.001W / mm} 3 , and the criteria for setting the correction coefficient α which is the inverse numbers ^is 1000mm ³ / W~4000mm 3 / W. The setting standard for the power constant a is 0.5 to 1.

  As described above, appropriate values of the correction coefficient and the power constant to be accumulated in the surface element control information database D3 can be determined in advance depending on the analysis object. For example, when performing thermal analysis of a notebook personal computer (hereinafter referred to as “notebook personal computer”), the values described above may be used. When performing thermal analysis of a house, the house will be larger in size and lower in heat generation density than a notebook computer, so the reference area Sk is large and the correction coefficient α is also large.

  Under the principle that “the same reference area Sk and correction coefficient α should be used in the analysis of the same kind of analysis object”, when the accuracy of radiation calculation is important, the smaller reference area Sk is used. However, if importance is placed on calculation speed or memory usage reduction, a larger reference area Sk may be used. If you want to adjust the surface element size based on the amount of heat generated even with a small amount of heat, use a larger correction coefficient α. If you want to increase the effect of adjusting the surface element size, use a larger power constant a. That's fine.

Formula (4) can be used as a calculation formula for calculating the target area S of the surface element.
S = min (Sk, (Sk / (α × Q / V) ^a )) (6)
Here, Sk is a reference area, α is a correction coefficient, a is a power constant, Q is a calorific value, and V is a volume. When the reference area Sk = 100 mm ² , the correction coefficient α = 2000 mm ³ / W, and the power constant a = 1.0, the target area S is
S = min (100, 100 / (2000 × Q / V))
It becomes.

For example, as a first example, in the case of a part having a calorific value Q = 1 W and a volume V = 400 mm ³ , 100 / (2000 × Q / V) = 100/2000/1 × 400 = 20 and S = min ( Since 100, 20) = 20, the target area S of the surface element is as small as 20 mm ² .

As a second example, in the case of a component having the same volume V = 400 mm ³ as the component of the first example, but a calorific value as small as Q = 0.5 W, 100 / (2000 × Q / V) = 100/2000 Since /0.5×400=40 and S = min (100, 40) = 40, the target area S of the surface element is 40 mm ² .

As a third example, in the case of a part having the same volume V = 400 mm ³ as the part of the first example but having a calorific value smaller than Q = 0.1 W, 100 / (2000 × Q / V) = 100 / Since 2000 / 0.1 × 400 = 200 and S = min (100, 200) = 100, the target area S of the surface element is 100 mm ² which is the same value as the reference area Sk.

As a fourth example, 100 / (2000 × Q / V) = 100/2000/10 in the case of a component having a volume V = 4000 mm ³ larger than that of the component of the first example and a calorific value Q = 20 W. Since × 4000 = 20 and S = min (100, 20) = 20, the target area S of the surface element is 20 mm ² .

In the case of a component that does not generate heat, since the heat generation amount Q is “0”, 100 / (2000 × Q / V) is infinite, and the target area S of the surface element is 100 mm ² .

  As described above, the CAD information database D1 and the surface element control information database D3 calculate the volume information indicating the volume of the plurality of parts, the heat generation information indicating the heat generation amount of the plurality of parts, and the target area of the surface element. A predetermined reference area, a predetermined correction coefficient, and surface element control information representing a constant to be determined are further stored.

The predetermined calculation formula is as follows: V indicates the volume indicated by the volume information stored in the CAD information database D1, Q indicates the heat generation amount indicated by the heat generation information stored in the CAD information database D1, and the surface element control information database D3. The predetermined reference area indicated by the stored surface element control information is Sk, the predetermined correction coefficient indicated by the surface element control information stored in the storage means is α, and the predetermined surface area control information stored in the storage means indicates in advance. If the constant to be determined is a and the target area S of the surface element for each part is S = min (Sk, (Sk / (α × Q / V) ^a )), the volume of the part and the calorific value of the part are The target area of the surface element can be calculated in consideration.

Formula (5) can also be used as a calculation formula for calculating the target area S of the surface element.
S = min (Sk, (Sk / (β × Q b / V c / D d))) ... (7)
Here, Sk is a reference area, β is a correction coefficient, b, c and d are power constants, Q is a calorific value, V is a volume, and D is a thermal conductivity. If Expression (5) is used, a part having a high thermal conductivity that is unlikely to cause a temperature difference in the part is less necessary to make the surface element finer, so that the target area S of the surface element can be set larger. The effect is obtained.

  The setting criteria for the correction coefficient β and the power constants b, c, and d are the same as the setting criteria for the correction coefficient α and the power constant a described above. That is, the power constants b, c, and d may be selected from about 0.5 to 1.0. The standard of thermal conductivity is that the object to be analyzed is a fine one on the order of μm, or a special material with extremely high or extremely low thermal conductivity is used. If it is a household appliance or a thing used on a daily basis, the standard value of thermal conductivity is about 1 W / m / K.

The correction factor β is
β = 1 / ((standard heating value) ^b / (standard volume) ^c / (standard thermal conductivity) ^d ))
Calculate from For example, assuming that the standard heating value = 0.2 W, the standard volume = 400 mm ³ , the standard thermal conductivity = 1 W / m / K, and b = c = d = 1.0,
β = 2000 mm ³ / m / K = 2 mm ² / K
It becomes.

  Thus, by the CAD information database D1, the material information database D2, and the surface element control information database D3, volume information representing the volume of the plurality of parts, heat generation amount information representing the heat generation amount of the plurality of parts, and the plurality of pieces Further stored is thermal conductivity information representing the thermal conductivity of the component, a predetermined reference area for calculating the target area of the surface element, a predetermined correction coefficient, and surface element control information indicating a constant to be determined. .

The predetermined calculation formula is stored in the material information database D2 as V indicating the volume indicated by the volume information stored in the CAD information database D1, Q as the heat generation amount indicated by the heat generation information stored in the CAD information database D1. D indicates the thermal conductivity indicated by the thermal conductivity information, Sk indicates the predetermined reference area indicated by the surface element control information stored in the surface element control information database D3, and the surface element control information stored in the storage means indicates in advance. S = min (Sk, (Sk) where β is a correction coefficient to be determined, b, c and d are constants to be determined in advance, which are indicated by the surface element control information stored in the storage means, and a target area S of the surface element for each part. / (Β × Q ^b / V ^c / D ^d ))).

  Therefore, the target area of the surface element can be calculated in consideration of the thermal conductivity of the part in addition to the volume of the part and the heat generation amount of the part, and the target area of the surface element of the part having a high thermal conductivity is set larger. can do.

  Referring to FIG. 1, a surface element model generation unit 15 which is a surface element model generation unit includes CAD information stored in a CAD information database D1, material information stored in a material information database D2, and a surface element control information database D3. A surface element model composed of surface elements is obtained by referring to the surface element control information stored in the 3D element information, the 3D element information stored in the 3D element information database D4, and the target area information stored in the surface element information database D5. The generated surface element information representing the generated surface element model is stored in the surface element information database D5.

  Specifically, adjacent surface polygons are combined to form a surface element having an area that is at least the target area of the surface element for each part indicated by the target area information stored in the surface element information database D5, A surface element model composed of the formed surface elements is generated. The surface polygon is a surface exposed to the surface of the part among the surfaces constituting the three-dimensional element. “Adjacent” is a relationship sharing one side of the surface polygon, and a relationship sharing only the vertices of the surface polygon is not considered to be adjacent.

  As selection criteria for adjacent surface elements, the normal direction of the surface polygons included in one surface element is aligned as the first priority condition, and the shape of the surface element is square as the second priority condition Both conditions are desirable, but both conditions are not essential.

  If an isolated surface polygon that does not have an adjacent unprocessed surface polygon remains unprocessed, a surface element having an area less than the target area S is finally formed, so that no isolated surface polygon remains. It is desirable to select as follows. Specifically, among unprocessed surface polygons, a triangular surface polygon has two sides, and a surface polygon composed of four or more sides has a surface polygon in which two or more sides have already been processed. Although it is desirable to select an adjacent raw surface polygon, this is not a requirement.

  Further, the surface element model generation unit 15 sets the maximum area of the surface element of the first part among the plurality of parts constituting the analysis target as the plurality of heat generation amounts less than the heat generation amount of the first component. The area of the surface element of the second part is less than the maximum area.

  As described above, the CAD information database D1 stores heat generation information indicating the heat generation amount of the plurality of parts, and the surface element model generation unit 15 stores the maximum surface element of the first part among the plurality of parts. The heat generation amount indicated by the heat generation information stored in the CAD information database D1 is less than the maximum area of the surface element of the second component among the plurality of components whose heat generation amount is less than the heat generation amount of the first component. Therefore, it is possible to calculate the target area of the surface element that can finely divide the surface of the part that generates a large amount of heat.

  Alternatively, the surface element model generation unit 15 calculates the area of the surface element of the part whose calorific value is not zero among the plurality of parts constituting the analysis target, as four times the area of the surface element of the part whose calorific value is zero. 1 or less.

  In this way, heat generation information representing the heat generation amounts of the plurality of parts is stored by the CAD information database D1, and heat generation information stored in the CAD information database D1 of the plurality of parts by the surface element model generation unit 15. The area of the surface element of the first part whose non-zero heat generation amount is indicated by the surface element of the second part whose heat generation amount indicated by the heat generation information stored in the CAD information database D1 among the plurality of parts is zero Therefore, it is possible to calculate the target area of the surface element that can divide the surface of the component that generates heat more finely than the surface of the component that does not generate heat.

  Or the surface element model production | generation part 15 makes the surface of the largest area among the surfaces which comprise the surface of the components in which the emitted-heat amount is not zero at least four surface elements.

  In this way, the heat generation information indicating the heat generation amount of the plurality of parts is stored by the CAD information database D1, and the heat generation amount indicated by the heat generation information stored in the CAD information database D1 by the surface element model generation unit 15 is not zero. Since the surface having the largest area among the surfaces constituting the surface of the component is at least four surface elements, the target area of the surface element that can finely divide the surface of the component that generates heat can be calculated. .

  Or the surface element model production | generation part 15 makes the surface of the largest area of the surfaces which comprise the surface of the components whose heat generation density is more than a reference | standard heat generation density as at least four surface elements.

  Thus, the heat generation density information indicating the heat generation density of the plurality of parts is stored by the material information database D2, and the heat generation density indicated by the heat generation density information stored in the material information database D2 by the surface element model generation unit 15 is obtained. Since the surface having the largest area among the surfaces constituting the surface of the component having a predetermined reference heat density or higher is at least four surface elements, the surface element can finely divide the surface of the component having a high heat generation density. The target area can be calculated.

  Or the surface element model production | generation part 15 makes the surface of the largest area of the surfaces which comprise the surface of components with thermal conductivity more than reference | standard thermal conductivity as at least four surface elements.

  As described above, the material information database D2 stores thermal conductivity information representing the thermal conductivity of the plurality of components, and the surface element model generation unit 15 indicates the thermal conductivity information stored in the material information database D2. The surface of the largest area among the surfaces constituting the surface of the component whose thermal conductivity is equal to or higher than a predetermined reference thermal conductivity is made into at least four surface elements, so the surface of the component with high thermal conductivity is finely divided. The target area of the surface element that can be calculated can be calculated.

  The thermal analysis unit 16 serving as a thermal analysis unit applies a finite element method, a finite difference to the three-dimensional element model generated by the three-dimensional element model generation unit 13 and the surface element model generated by the surface element model generation unit 15. Method or numerical analysis such as finite volume method.

  The output unit 17 outputs, as output information, analysis results obtained by the thermal analysis performed by the thermal analysis unit 16, for example, information indicating values such as temperature or heat flux of each unit, and stores the output information output in the output result database D6. To do.

  FIG. 3 is a diagram illustrating an example of the analysis object 20 on which the thermal analysis is performed by the thermal analysis apparatus 1. FIG. 3A is a perspective view of the analysis object 20. The analysis target 20 includes a housing 21, a substrate 22 provided in the housing 20, and a heat source 23 provided in the center on the substrate 22. Two vent holes 24 are formed in the housing 21. FIG. 3B is a top view of the analysis object 20, and FIG. 3C is a front view of the analysis object 20.

  The housing 21 is 300 mm in the X-axis direction, 200 mm in the Y-axis direction, and 50 mm in the Z-axis direction. The substrate 22 has an X-axis direction of 260 mm, a Y-axis direction of 160 mm, and a Z-axis direction of 2 mm. The heat source 23 has an X-axis direction of 10 mm, a Y-axis direction of 10 mm, and a Z-axis direction of 10 mm. The thermal conductivity of each member is 0.2 W / m / K for the casing 21, 20 W / m / K for the substrate 22, and 4 W / m / K for the heat source 23.

  4 to 6 are diagrams showing examples of models in which the thermal analysis target 20 shown in FIG. 3 is divided into surface elements for radiation calculation. FIG. 4 is a diagram showing a model A in which the whole is divided into coarse radiation calculation surface elements of equal size by a conventional technique. FIG. 4A is a diagram showing a model 21a of the model A in which the entire casing 21 is divided into rough radiation calculation surface elements of the same size, and FIG. It is a figure which shows the model 22a and the model 23a which divided | segmented the whole 22 and the heat source 23 into the surface element for coarse radiation calculation with equal size, respectively.

  FIG. 5 is a diagram showing a model B in which the whole is divided into fine radiation calculation surface elements of the same size by a conventional technique. FIG. 5A is a diagram showing a model 21b of the model B in which the entire casing 21 is divided into fine radiation calculation surface elements of the same size, and FIG. It is a figure which shows the model 22b and the model 23b which divided | segmented the whole 22 and the heat source 23 into the surface element for radiation calculation with equal size, respectively.

  FIG. 6 is a diagram illustrating a model C in which the basic size of the surface element is the same as that of the model A but the number of divisions of the heat source 23 is increased by the thermal analysis apparatus 1 according to the present invention. 6A is a diagram showing a model 21c of the model C in which the casing 21 is divided into the same size as the model A, and FIG. 6B is a diagram of the model C. It is a figure which shows the model 22c which increased the division | segmentation number of the heat source 23 from the model 22c which made the board | substrate 22 the basic size of the surface element the same size as the model A, and the model A.

  Thermal analysis is performed on models A to C when the ambient temperature is 20 degrees Celsius and the heat source 23 is given a total heating value of 10 W, and the number of radiation calculation surface elements, calculation time, and heat source for each model Table 1 shows the results of the temperature comparison.

  It can be seen that the calculation result equivalent to that of the model B obtained by fine surface element division is obtained in the model C in a short calculation time that is the same as that of the model A.

  As described above, according to the thermal analysis device 1 of the present invention, it is possible to perform highly accurate radiation calculation in a short calculation time, and it is possible to realize a reduction in design period and a reduction in design cost.

  As described above, the CAD information database D1 stores shape information representing the shapes of a plurality of parts constituting the analysis target, and the three-dimensional element model generation unit 13 indicates the shape information stored in the CAD information database D1. The shape of the part is divided for each part, a three-dimensional element model including a three-dimensional polyhedron is generated, and the target area of the surface element including the surface part constituting the surface of the part is generated by the surface element target area calculation unit 14. Is calculated for each part by a predetermined calculation formula for calculating the target area.

  Then, the adjacent surface exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated by the three-dimensional element model generating unit 13 is combined by the surface element model generating unit 15 to obtain the surface element target area. A surface element model composed of surface elements having an area equal to or larger than the target area calculated for each part by the calculation unit 14 is generated, and the surface element model generated by the surface element model generation unit 15 by the thermal analysis unit 16 is generated. Thermal analysis is performed by calculating thermal radiation from the surface of each component.

  Therefore, it is possible to avoid making the surface element unnecessarily fine by setting the surface element to a surface element larger than the target area calculated for each part by a predetermined calculation formula. A highly accurate radiation calculation can be executed.

  FIG. 7 is a flowchart showing the processing procedure of the thermal analysis process of the thermal analysis apparatus 1. This flowchart is processed by the CPU executing a program stored in the storage device, and is also a flowchart showing the processing steps of the thermal analysis method according to the present invention. When execution of the thermal analysis process is instructed from the input device of the thermal analysis apparatus 1, the process proceeds to step A1.

  In step A1, CAD information, for example, information representing the shape, material type, calorific value, position information, etc. of each part included in the analysis object is input from the input device by the shape information input unit 11, and the input CAD Information is stored in the CAD information database D1. When the CAD information designed by the CAD device is stored in the CAD device connected to the LAN, the CAD information may be received from the CAD device by the communication device and stored in the CAD information database D1. CAD information designed by the CAD device may be stored in advance in the CAD information database D1, and step A1 may be skipped.

  In step A2, which is a three-dimensional element model generation process, the three-dimensional element model generation unit 13 converts each part included in the analysis target into a three-dimensional polyhedron, for example, based on CAD information stored in the CAD information database D1. Dividing into tetrahedral or hexahedral three-dimensional elements, a three-dimensional element model composed of the divided three-dimensional elements is generated. Then, the three-dimensional element information representing the generated three-dimensional element model is stored in the three-dimensional element information database D4.

  For the division into three-dimensional elements, the Delaunay division method, which is a general division method into tetrahedral elements, is widely known, and these methods can be used. Specific division methods are described in, for example, “Automatic Element Division Method for 3D FEM (Finite Element Method)” published by Morikita Publishing, Takeo Taniguchi, and Kiyoaki Moriwaki.

  In step A3 which is a surface element target area calculation step, the surface element target area calculation unit 14 calculates the target area of the surface element for each part. In step A4, which is a surface element model generation process, the surface element model generation unit 15 combines adjacent surface polygons to generate a surface element model composed of surface elements having an area larger than the target area.

  In step A5 which is a thermal analysis process, the thermal analysis unit 16 applies a finite element to the three-dimensional element model generated by the three-dimensional element model generation unit 13 and the surface element model generated by the surface element model generation unit 15. Thermal analysis by numerical analysis such as finite difference method, finite difference method, or finite volume method. In step A6, the output unit 17 outputs, as output information, an analysis result obtained by the thermal analysis performed by the thermal analysis unit 16, for example, information indicating values such as temperature or heat flux of each unit, and ends the thermal analysis process. .

  FIG. 8 is a flowchart showing a processing procedure of a surface element target area calculation process called from the thermal analysis process. The surface element target area calculation processing is processed by the surface element target area calculation unit 14. When called from step A3 in the flowchart shown in FIG. 7, the process proceeds to step B1.

  In step B1, the surface element control information is acquired from the surface element control information database D3. In step B2, it is determined whether or not the calculation of the target area of the surface elements for all parts has been completed. If it is completed for all parts, the surface element target area calculation process is terminated. If it is not completed for all parts, the process proceeds to step B3.

  In step B3, the calorific value and volume of the processing target component are acquired from the CAD information stored in the CAD information database D1. In step B4, based on the reference area, power constant, and correction coefficient of the surface element indicated by the surface element control information acquired in step B1, and the amount of heat and volume acquired in step B3, equation (4) or equation (5) ) To calculate the target area S of the surface element, and the process returns to step B2.

  FIG. 9 is a flowchart showing the processing procedure of the surface element generation processing called from the thermal analysis processing. The surface element generation processing is processed by the surface element model generation unit 15. When called from step A4 in the flowchart shown in FIG. 7, the process proceeds to step C1.

  In step C1, it is determined whether all surface polygons of the part have been processed. If all surface polygons have been processed, the surface element generation process is terminated. If all surface polygons have not been processed, the process proceeds to step C2.

  In Step C2, one unprocessed surface polygon is selected to be a surface element. If an isolated surface polygon that does not have an adjacent unprocessed surface polygon remains unprocessed, a surface element having an area less than the target area S is finally formed, so that no isolated surface polygon remains. It is desirable to select as follows. Specifically, among unprocessed surface polygons, a triangular surface polygon has two sides, and a surface polygon composed of four or more sides has a surface polygon in which two or more sides have already been processed. Although it is desirable to select an adjacent raw surface polygon, this is not a requirement.

  In step C3, it is determined whether the area of the surface element being created is equal to or larger than the target area S. If it is equal to or larger than the target area S, the process proceeds to Step C6, and if it is not equal to or larger than the target area S, the process proceeds to Step C4. In Step C4, it is determined whether there is an unprocessed surface polygon adjacent to the surface element being created. If there is an unprocessed surface polygon, the process proceeds to step C5, and if there is no unprocessed surface polygon, no further enlargement can be made, so the process proceeds to step C6.

  In step C5, one of the adjacent surface polygons is added to the surface element being created, and the process returns to step C3. As selection criteria for adjacent surface elements, the normal direction of the surface polygons included in one surface element is aligned as the first priority condition, and the shape of the surface element is square as the second priority condition Both conditions are desirable, but both conditions are not essential. In step C6, the creation of one surface element is completed, the surface element for which the creation has been completed is registered in the surface element information database D5, and the process returns to step C1.

  Thus, in the flowchart showing the processing procedure of the thermal analysis process shown in FIG. 7, in step A2, the shape information stored in the storage device that stores the shape information representing the shapes of the plurality of parts constituting the analysis object. The shape of the part indicated by is divided for each part to generate a three-dimensional element model composed of a three-dimensional polyhedron. In step A3, the target area of the surface element composed of the surface part constituting the surface of the part is determined as the target The calculation is performed for each part using a predetermined calculation formula for calculating the area.

  In step A4, adjacent faces exposed on the surface of the part among the faces of the polyhedron of the three-dimensional element model generated in step A2 are combined to exceed the target area calculated for each part in step A3. A surface element model composed of surface elements having an area is generated, and in step A5, thermal analysis is performed on the surface element model generated in step A4 by calculating thermal radiation from the surface of each component.

  Therefore, if the thermal analysis method according to the present invention is used, it is possible to make the surface element finer than necessary by making the surface element larger than the target area calculated for each part by a predetermined calculation formula for the size of the surface element. Since this can be avoided, highly accurate radiation calculation can be executed in a short calculation time.

  The program for controlling the thermal analysis device 1 is also a program for causing the CPU included in the thermal analysis device 1 to execute each step of the thermal analysis method. Therefore, the present invention can be provided as a program for causing a computer to execute each step of the thermal analysis method.

  In the above-described embodiment, the program is stored in a storage device of the thermal analysis device 1, for example, a storage device such as a semiconductor memory or a hard disk device, but is not limited to these storage devices and is read by a computer. It may be recorded on a possible recording medium. The recording medium may be a recording medium that can be read by providing a program reading device as an external storage device (not shown) and inserting the recording medium therein, or may be a storage device of another device. .

  Any recording medium may be used as long as the program stored in the recording medium is accessed from a computer and executed. In other words, any recording medium may be used as long as the program is read from the recording medium, the read program is stored in the program storage area of the storage device, and the program is executed. Further, it may be downloaded from another device via a communication network and stored in the program storage area. The download program is stored in advance in a storage device of the computer 10 or installed in a program storage area from another recording medium.

  The recording medium configured to be separable from the main body is, for example, a tape-based recording medium such as a magnetic tape / cassette tape, a magnetic disk such as a flexible disk / hard disk, or a CD-ROM (Compact Disk Read Only Memory) / MO (Magneto Optical). disk) / MD (Mini Disc) / DVD (Digital Versatile Disk) and other optical disk recording media, IC (Integrated Circuit) cards (including memory cards) / optical cards and other card recording media, or masks It may be a recording medium that carries a fixed program including a semiconductor memory such as ROM / EPROM (Erasable Programmable Read Only Memory) / EEPROM (Electrically Erasable Programmable Read Only Memory) / flash ROM. Therefore, the present invention can be provided as a computer-readable recording medium recording a program for causing a computer to execute each step of the thermal analysis method.

1 is a block diagram showing a configuration of a thermal analysis device 1 that is an embodiment of the present invention. It is a figure for demonstrating radiant heat transfer. It is a perspective view of an example of the analysis target object 20 in which thermal analysis is performed by the thermal analysis apparatus 1. It is a figure which shows the example of the model which divided | segmented the thermal analysis object 20 shown in FIG. 3 into the surface element for radiation calculation. It is a figure which shows the example of the model which divided | segmented the thermal analysis object 20 shown in FIG. 3 into the surface element for radiation calculation. It is a figure which shows the example of the model which divided | segmented the thermal analysis object 20 shown in FIG. 3 into the surface element for radiation calculation. 3 is a flowchart showing a processing procedure of thermal analysis processing of the thermal analysis device 1. It is a flowchart which shows the process sequence of the surface element area calculation process called from a thermal analysis process. It is a flowchart which shows the process sequence of the surface element production | generation process called from a thermal analysis process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal analysis apparatus 10 Control part 11 Shape information input part 12 Material physical property value input part 13 Three-dimensional element model generation part 14 Area element target area calculation part 15 Area element model generation part 16 Thermal analysis part 17 Output part 20 Analysis object 21 , 21a-21c Housing 22, 22a-22c Substrate 23, 23a-23c Heat source 24 Ventilation hole 31 Surface A
32 side B
D1 CAD information database D2 Material information database D3 Surface element control information database D4 Three-dimensional element information database D5 Surface element information database D6 Output result database R0 to R2 Micro area

Claims (11)

Storage means for storing shape information representing the shapes of a plurality of parts constituting the analysis object;
Three-dimensional element model generation means for generating a three-dimensional element model composed of a three-dimensional polyhedron by dividing the shape of the part indicated by the shape information stored in the storage means for each part;
A surface element target area calculating means for calculating a target area of a surface element composed of a portion of a surface constituting a surface of the component for each component by a predetermined calculation formula for calculating the target area;
The target area calculated for each part by the surface element target area calculating means by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated by the three-dimensional element model generating means A surface element model generating means for generating a surface element model composed of surface elements of the above area;
A thermal analysis apparatus comprising: thermal analysis means for calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated by the surface element model generation means. The storage means further stores heat generation information indicating the heat generation amount of the plurality of parts,
The surface element model generation means is configured such that the heat generation amount indicated by the heat generation information stored in the storage means is less than the heat generation amount of the first component. The thermal analysis apparatus according to claim 1, wherein the area is less than the maximum area of the surface element of the second part among the plurality of parts. The storage means further stores heat generation information indicating the heat generation amount of the plurality of parts,
The surface element model generation means calculates the area of the surface element of the first part whose heat generation amount indicated by the heat generation information stored in the storage means among the plurality of parts is not zero. 2. The thermal analysis apparatus according to claim 1, wherein the heat generation amount stored in the storage means is not more than one-fourth of the area of the surface element of the second component for which the heat generation amount is zero. The storage means further stores heat generation information indicating the heat generation amount of the plurality of parts,
The surface element model generating means sets at least four surface elements to have a surface with the largest area among the surfaces constituting the surface of the component whose heat generation amount indicated by the heat generation information stored in the storage means is not zero. The thermal analysis apparatus according to claim 1, wherein The storage means further stores heat density information representing heat density of the plurality of parts,
The surface element model generation means has at least four surfaces having the largest area among the surfaces constituting the surface of the component having a heat generation density indicated by the heat generation density information stored in the storage device equal to or higher than a predetermined reference heat generation density. The thermal analysis apparatus according to claim 1, wherein the thermal analysis apparatus is a surface element. The storage means further stores thermal conductivity information representing the thermal conductivity of the plurality of components,
The surface element model generation means has a surface with the largest area among the surfaces constituting the surface of the component having a thermal conductivity indicated by the thermal conductivity information stored in the storage means equal to or higher than a predetermined reference thermal conductivity. The thermal analysis apparatus according to claim 1, wherein the thermal analysis apparatus includes at least four surface elements. The storage means includes volume information indicating the volume of the plurality of parts, heat generation information indicating the heat generation amount of the plurality of parts, a predetermined reference area for calculating a target area of the surface element, and a predetermined correction coefficient. And surface element control information representing constants to be determined in advance,
The predetermined calculation formula is such that the volume indicated by the volume information stored in the storage means is V, the heat generation amount indicated by the heat generation amount information stored in the storage means is Q, and the surface element control information stored in the storage means. The predetermined reference area indicated by is Sk, the predetermined correction coefficient indicated by the surface element control information stored in the storage means is α, and the constant to be determined indicated by the surface element control information stored in the storage means is a. When the surface area target area S for each part is
S = min (Sk, (Sk / (α × Q / V) ^a ))
The thermal analysis apparatus according to claim 1, wherein: The storage means includes volume information indicating the volume of the plurality of parts, heat generation information indicating the heat generation amount of the plurality of parts, heat conductivity information indicating the thermal conductivity of the plurality of parts, and surface elements. Further storing a predetermined reference area for calculating the target area, a predetermined correction coefficient, and surface element control information representing a constant to be determined,
The predetermined calculation formula is such that the volume indicated by the volume information stored in the storage means is V, the heat generation amount indicated by the heat generation amount information stored in the storage means is Q, and the thermal conductivity information stored in the storage means. D, the predetermined reference area indicated by the surface element control information stored in the storage means Sk, the predetermined correction coefficient indicated by the surface element control information stored in the storage means β, the storage When the constants to be predetermined indicated by the surface element control information stored in the means are b, c and d, the target area S of the surface element for each part is:
S = min (Sk, (Sk / (β × Q b / V c / D d)))
The thermal analysis apparatus according to claim 1, wherein: A three-dimensional element model composed of a three-dimensional polyhedron is obtained by dividing the shape of a part indicated by the shape information stored in a storage device that stores shape information representing the shape of a plurality of parts constituting the analysis object into parts. A three-dimensional element model generation step to generate;
A surface element target area calculation step for calculating a target area of a surface element composed of a part of a surface constituting the surface of the part for each part by a predetermined calculation formula for calculating the target area;
The target area calculated for each part in the surface element target area calculation step by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated in the three-dimensional element model generation step A surface element model generation step for generating a surface element model composed of surface elements of the above area;
A thermal analysis method comprising: a thermal analysis step of calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated in the surface element model generation step. A three-dimensional element model composed of a three-dimensional polyhedron is obtained by dividing the shape of a part indicated by the shape information stored in a storage device that stores shape information representing the shape of a plurality of parts constituting the analysis object into parts. A three-dimensional element model generation step to generate;
A surface element target area calculation step for calculating a target area of a surface element composed of a part of a surface constituting the surface of the part for each part by a predetermined calculation formula for calculating the target area;
The target area calculated for each part in the surface element target area calculation step by combining adjacent faces exposed on the surface of the part among the polyhedral faces of the three-dimensional element model generated in the three-dimensional element model generation step A surface element model generation step for generating a surface element model composed of surface elements of the above area;
A program for causing a computer to execute a thermal analysis process for calculating thermal radiation from the surface of each component and performing thermal analysis on the surface element model generated in the surface element model generation process.   The computer-readable recording medium which recorded the program of Claim 10.