JP5045348B2 - Boundary condition setting method for structural analysis model - Google Patents

Description

  The present invention relates to a structural analysis model created for a structure having an internal space in which an open portion that opens to the outside and fluid flows in and out through the open portion, and data of the fluid analysis model created for the fluid in the internal space Belongs to the technical field related to the boundary condition setting method of the structural analysis model.

  Conventionally, for example, in an engine cylinder head, a structural analysis model composed of a large number of elements (mesh) is created from the three-dimensional design data of the cylinder head, and a large number of fluids such as cooling water flowing in the internal space of the cylinder head are used. A fluid analysis model consisting of the elements (mesh) is created, and the surface of the fluid analysis model is applied to each element in the portion corresponding to the surface that exchanges heat with the fluid (that is, the surface that contacts the internal space) in the structural analysis model. The element data (temperature and heat transfer coefficient) are set as boundary conditions (data mapping is performed), and heat transfer calculation and stress calculation are performed using the structural analysis model. Stress analysis is performed.

The data mapping operation as described above can be performed automatically by a computer as shown in, for example, Patent Document 1, and can be performed in a shorter time compared to the case where the operator performs the operation manually.
JP 2001-82391 A

  By the way, when the data of the fluid analysis model created for the fluid in the internal space is set as a boundary condition in the structural analysis model created for the structure having the internal space such as the cylinder head (when data mapping is performed), In the structural analysis model, an element in the part corresponding to the surface in contact with the internal space of the structure is extracted, and the element data of the fluid analysis model corresponding to the element is set as a boundary condition for the extracted element. To do. Here, the portion corresponding to the internal space in the structural analysis model and the fluid analysis model have the same shape, and the extracted elements on the surface of the fluid analysis model when the fluid analysis model is superimposed on the portion. The element in contact with is an element of the fluid analysis model corresponding to the extracted element.

  When data mapping is performed as described above, it is necessary to extract the element to which the data of the fluid analysis model should be added from the structural analysis model, but this element is in a portion corresponding to the outer surface of the structure. If it is an element, it is located on the outer surface of the structural analysis model, so that the element can be easily extracted.

  However, since the element to be extracted is an element in a portion corresponding to the surface in contact with the internal space, there is a problem that it takes a considerable time to extract the element. That is, the elements to be extracted are not on the outer surface of the structural analysis model, but are inside the structural analysis model, and in order to extract the elements inside the elements, they are sequentially removed from the outer surface elements in the structural analysis model. Therefore, there is a problem that the operation time becomes considerably long.

  The present invention has been made in view of such a point, and an object of the present invention is to create a structure having an open space that opens to the outside and an internal space through which fluid flows in and out. When the data of the fluid analysis model created for the fluid in the internal space is set as a boundary condition in the structural analysis model, the elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model for a short time It is to be able to extract with.

In order to achieve the above object, according to the present invention, an internal space of a structure is provided in a structural analysis model created for a structure having an open space that opens to the outside and that has an internal space through which fluid flows in and out. The operator sets, as a reference element , an arbitrary element in a portion corresponding to the end corresponding to the open portion in the surface in contact with the internal space among all elements in the portion corresponding to the surface in contact with the internal space. to control operation of the computer, the in structural analysis model the set reference elements in the nucleus, it is adjacent one after another, the internal elements in the portion corresponding to the surface contacting the space boundary condition setting target Extracted as an element.

Specifically, in the invention according to claim 1, in the structural analysis model composed of a large number of elements, an open portion that opens to the outside is provided and a structure having an internal space through which fluid flows in and out is formed. A fluid composed of a number of elements created for the fluid in the internal space in order to perform heat transfer calculation or stress calculation of the structure on each element in the portion corresponding to the surface in contact with the internal space of the structure The object is a method for setting a boundary condition of a structural analysis model by a computer , in which data of the analysis model is set as a boundary condition.

Then, the computer includes a processing unit for performing arithmetic processing, the operator, from among all the elements in the portion corresponding to the surface in contact with the interior space of the structure in the structural analysis model, in contact with the internal space those having a reference element input means for setting an arbitrary element in the portion corresponding to the end portion corresponding to the opening in the plane as a reference element, the arithmetic processing unit, the in the structural analysis model Boundary condition setting target element extraction step for extracting, as a boundary condition setting target element, elements that are adjacent to each other and corresponding to the surface that touches the internal space, with the reference element set by the reference element input means as a core When, the arithmetic processing unit, for all boundary conditions set target element extracted in the boundary condition setting target element extraction step including the reference element, It is intended to include a boundary condition setting step of setting a data element of the fluid dynamics model corresponding to the boundary condition setting target element as a boundary condition.

With the above configuration, the reference element input means allows the open portion (that is, the fluid inlet) on the surface in contact with the internal space to be out of all elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model. Alternatively, an element in a portion corresponding to the end corresponding to the outlet) is set as a reference element. Subsequently, in the boundary condition setting target element extraction step, the reference element set by the reference element input means in the structural analysis model is used as a core, and the portion corresponding to the surface adjacent to the internal space is adjacent to the reference element. A certain element is extracted as a boundary condition setting target element. Next, in the boundary condition setting step, the data of the element of the fluid analysis model corresponding to the boundary condition setting target element is set as the boundary condition for all the boundary condition setting target elements including the reference element.

The reference element is not an element in the portion corresponding to the outer surface of the structure, but corresponds to the outer surface because it is an element in the portion corresponding to the open portion on the surface in contact with the internal space. It is an element that is visible to the operator, as is the element in the part. As a result, the reference element can be easily set by the operator himself / herself while viewing the structural analysis model.

  An element adjacent to the reference element and corresponding to the surface of the structure (an element in which at least one surface of the element is not in contact with another element) can be automatically extracted by a computer. Here, since the reference element is an element in a portion corresponding to the surface in contact with the internal space in the structural analysis model, the elements in the portion corresponding to the surface of the structure, which are adjacent to each other, are usually internal. It is an element in the part corresponding to the surface in contact with the space. On the other hand, when the extracted boundary condition setting target element is at the boundary between the surface in contact with the internal space and the outer surface, the element in the portion corresponding to the surface of the structure adjacent to the boundary condition setting target element is the structure. There is a high possibility that the element is in a portion corresponding to the outer surface. Since the element in the part corresponding to the outer surface can be easily identified, it is determined whether the element is in the part corresponding to the outer surface, and the part corresponding to the outer surface of the structure. If it is not an element in the area, it is determined that the element is in a part corresponding to the surface in contact with the internal space, the element is extracted, and the element in the part corresponding to the outer surface of the structure is not extracted. That's fine. In this way, elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model can be extracted easily and in a short time. Therefore, the extraction time of the boundary condition setting target element can be greatly shortened.

According to a second aspect of the present invention, in the first aspect of the invention, the computer includes an outer surface element input means for allowing an operator to specify an element in a portion corresponding to the outer surface of the structure in the structural analysis model. In the boundary condition setting target element extraction step, the arithmetic processing unit is arranged on the surface of the structure adjacent to the reference element or the extracted boundary condition setting target element in the structural analysis model. A selection step of selecting an element in the corresponding part, and the arithmetic processing unit is an element in the part corresponding to the outer surface of the structure specified by the outer surface element input means. a determination step of whether or not there, the arithmetic processing unit determines that not the element at the portion corresponding to the outer surface of the structure in the above determination step elements , Have an extraction step of extracting as the boundary condition setting target element, assumed to be a repeating the selecting step, the determination step and the extraction step in this order.

  Thus, in the selection step, an element in the portion corresponding to the surface of the structure adjacent to the reference element or the boundary condition setting target element in the structural analysis model is once selected. In the determination step, the selected element is selected. It is determined whether or not the element is in a portion corresponding to the outer surface of the structure, and in the extraction step, the element determined not to be an element in the portion corresponding to the outer surface of the structure (that is, a surface in contact with the inner space) The element in the portion corresponding to (2) is extracted as the boundary condition setting target element, and the selection step, the determination step, and the extraction step are repeatedly executed in this order. As a result, it is possible to reliably extract only the elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model.

In the invention of claim 3, in the invention of claim 2, the boundary condition setting target element extraction step includes a counting step in which the arithmetic processing unit counts up the number of boundary condition setting target elements after the extraction step. Further, the arithmetic processing unit stops the boundary condition setting target element extraction step when the count number in the counting step does not increase.

  That is, when extraction of all the boundary condition setting target elements is completed, the elements selected in the selection step are only elements in the portion corresponding to the outer surface of the structure, and the count number does not increase. Therefore, when the count no longer increases, all elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model have been extracted. At that time, the boundary condition setting target element extraction step is performed. By canceling, it is possible to prevent a state in which only elements in a portion corresponding to the outer surface of the structure are selected after completion of extraction of all boundary condition setting target elements. Therefore, the completion of extraction of all the boundary condition setting target elements can be appropriately determined, and wasteful processing can be eliminated, thereby improving processing efficiency.

As described above, according to the boundary condition setting method of the structural analysis model of the present invention, the structural analysis created for the structure having an open space that opens to the outside and having an internal space through which fluid flows in and out through the open space. from all elements in the portion corresponding to the surface in contact with the interior space of the structure in the model, any element in the portion corresponding to the end portion corresponding to the opening in the surface in contact with the internal space, the operator Is set as a reference element, and the control calculation unit of the computer uses the set reference element in the structural analysis model as a core, and successively adjoins the portion corresponding to the surface in contact with the internal space. By extracting an element as a boundary condition setting target element, there is a requirement in the part corresponding to the surface in contact with the internal space of the structure in the structural analysis model. Easily and can be extracted in a short time, the extraction time of the boundary condition setting target element can be greatly shortened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a work procedure when conducting heat conduction analysis or thermal stress analysis of a structure having an internal space through which a fluid flows. The internal space has an open portion that opens to the outside of the structure, and the fluid flows into and out of the internal space through the open portion. The steps of the following flowcharts are basically processes performed by a computer, but also include processes performed by an operator. When an operator performs the process, the fact is clearly indicated.

  First, three-dimensional (3D) design data (for example, CAD data) of a structure having an internal space through which fluid flows is input from a storage device that stores the three-dimensional design data (step S1).

  Subsequently, a fluid analysis model including a large number of elements (tetramesh, hexamesh, etc.) is created for the fluid in the internal space from the 3D design data (step S2). The fluid analysis model is created using existing general-purpose finite element software. Then, the operator sets the boundary condition of the fluid (step S3), executes the fluid calculation (thermal fluid analysis) based on the fluid analysis model and the boundary condition (step S4), and shows the calculation result. Post processing for outputting data (temperature and heat transfer coefficient) for each element is performed (step S5).

  On the other hand, in parallel with the thermal fluid analysis for the fluid, a structural analysis model composed of a large number of elements (tetramesh, hexamesh, etc.) is created for the structure from the 3D design data (step S6). Similar to the fluid analysis model, this structural analysis model is also performed using existing general-purpose finite element method software. Note that the size of the element of the structural analysis model is larger than the size of the element of the fluid analysis model.

  Subsequently, all elements in the portion corresponding to the surface in contact with the internal space of the structure, that is, elements to which the data of the fluid analysis model should be added (hereinafter referred to as boundary condition setting target elements) are extracted from the structural analysis model. Then, the extracted all boundary condition setting target elements (including reference elements described later) are output (step S8).

  Next, data mapping is performed to assign the fluid analysis model data to the extracted boundary condition setting target element (the fluid analysis model data is set as the boundary condition) (step S9), and the above-described assignment is given to the structural analysis model. The obtained data is taken into an input file for heat transfer calculation (or thermal stress calculation) (step S10), and heat transfer calculation (or thermal stress calculation) is executed in the structural analysis model (step S11). Post processing for outputting data (temperature or thermal stress) for each element is performed (step S12).

  In the present embodiment, the extraction of the boundary condition setting target element in step S7 is specifically performed as shown in the flowchart of FIG.

That is, first, an operator designates an element in a portion corresponding to the outer surface of the structure in the structural analysis model (that is, an element on the outer surface of the structural analysis model) (step S21). In the structural analysis model, the worker selects a portion corresponding to the end corresponding to the open portion on the surface in contact with the internal space from all elements in the portion corresponding to the surface in contact with the internal space of the structure. An arbitrary element (an element visible to the operator) is set as a reference element (step S22). This reference element is the boundary condition setting target element.

  Then, in the structural analysis model, the element in the portion corresponding to the surface in contact with the internal space adjacent to the reference element is extracted as a boundary condition setting target element. Specifically, the surface of the structure (the surface in contact with the outer surface and the inner space) adjacent to the reference element (the boundary condition setting target element extracted in step S25 described later when returning from step S28 described later). ) Is selected (step S23), and it is determined whether or not the selected element is an element in the portion corresponding to the outer surface of the structure designated in step S21 (step S23). Step S24).

  When the selected element is not an element in a portion corresponding to the outer surface, that is, an element in a portion corresponding to a surface in contact with the internal space (when the determination in step S24 is NO), the selected element is selected. Elements are extracted as boundary condition setting target elements (step S25), and then the number of boundary condition setting target elements is counted up (step S26), and then the process proceeds to step S28.

  On the other hand, when the selected element is an element in a portion corresponding to the outer surface (when the determination in step S24 is YES), the selected element is not extracted as a boundary condition setting target element (step S27), the process proceeds to step S28.

  In step S28, it is determined whether or not the count number of the boundary condition setting target element is increased (step S28). When the count number is increased (when the determination in step S28 is YES), the above step is performed. Returning to S23, this time, an element adjacent to the extracted boundary condition setting target element is selected, and the processes of steps S24 to S28 are repeated. On the other hand, when the count number does not increase (when the determination in step S28 is NO), that is, extraction of all the boundary condition setting target elements is completed, and only the elements in the portion corresponding to the outer surface are selected. Sometimes, the boundary condition setting target element extraction process is stopped.

  The element extracted as the boundary condition setting target element is stored in the storage device of the computer. However, in this embodiment, in order to simplify the processing, the selected element is extracted as the boundary condition setting target element. The element which does not do is not memorized. For this reason, although the element extracted as the boundary condition setting target element is not selected again, the element that has been selected but not extracted as the boundary condition setting target element may be selected again. Even if it does in this way, since it is not extracted as a boundary condition setting object element, there is no problem.

In the above extraction method, elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model can be extracted easily and in a short time. That is, the element in the part corresponding to the surface in contact with the internal space of the structure is different from the element in the part corresponding to the outer surface and is inside the structural analysis model. Therefore, it is necessary to extract by sequentially removing elements from the outer surface in the structural analysis model. On the other hand, the reference element is an element in a portion corresponding to the surface in contact with the internal space, but is an element in a portion corresponding to the open portion in the surface in contact with the internal space. It is a visible element, and the reference element can be easily set by the operator himself / herself while specifying the structural analysis model. An element adjacent to the reference element and corresponding to the surface of the structure (an element in which at least one surface of the element is not in contact with another element) can be automatically extracted by a computer. Here, since the reference element is an element in a portion corresponding to the surface in contact with the internal space in the structural analysis model, the element in the portion corresponding to the surface of the structure adjacent to the reference element one after another is Usually, the element is in a portion corresponding to the surface in contact with the internal space, but may be an element in a portion corresponding to the outer surface of the structure. Since the element in the part corresponding to the outer surface can be easily identified, it is determined whether the element is in the part corresponding to the outer surface, and the part corresponding to the outer surface of the structure. If it is not an element, it can be determined that the element is in a part corresponding to the surface in contact with the internal space, and as described above, the element is extracted and the element in the part corresponding to the outer surface of the structure Do not extract. In this way, it is possible to easily and quickly extract elements in a portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model.

Here, the reference element may be one or plural, and it is preferable to set a plurality of reference elements particularly when a plurality of open portions are provided. In this case, it is preferable that the plurality of reference elements be elements respectively in portions corresponding to end portions corresponding to different open portions on the surface in contact with the internal space in the structural analysis model. In this way, the boundary condition setting target element extraction process can be completed in a shorter time.

  Specifically, the data mapping in step S9 is performed as shown in the flowchart of FIG.

  Initially, the operator uses a common three-dimensional coordinate axis (X axis, Y axis) for both models so that the part corresponding to the internal space in the structural analysis model and the same part of the fluid analysis model have the same coordinates. Axis and Z axis) are set (step S51). That is, in the space defined by the three-dimensional coordinate axis, the positional relationship between the two models is made the same as the positional relationship between the structure and the fluid. Here, the portion corresponding to the internal space in the structural analysis model has the same shape as the fluid analysis model, and in the space defined by the three-dimensional coordinate axis, the fluid analysis is performed on the portion corresponding to the internal space in the structural analysis model. The models just overlap. The setting of the three-dimensional coordinate axis may be automatically performed by a computer.

  Subsequently, in the space defined by the three-dimensional coordinate axis where the structural analysis model exists, the portion configured by the boundary condition setting target element in the structural analysis model spans a plurality of structural analysis side regions. The region is divided into a plurality of structural analysis side regions. In the present embodiment, first, the coordinates of the center of the portion constituted by the boundary condition setting target element in the structural analysis model (hereinafter referred to as the structural analysis model center) by the three-dimensional coordinate axis are obtained (step S52). Specifically, the maximum value and the minimum value of the X coordinate are extracted from the center coordinate data of each of the boundary condition setting target elements by extracting the maximum value and the minimum value of the X coordinate, the Y coordinate, and the Z coordinate. Is the X coordinate of the center of the structural analysis model, the average value of the maximum and minimum values of the Y coordinate is the Y coordinate of the center of the structural analysis model, and the average value of the maximum and minimum values of the Z coordinate. Is the Z coordinate of the center of the structural analysis model.

  Then, the space where the structural analysis model exists is defined with respect to the structural analysis model center, the first structural analysis side region F1 on the X axis positive side, the Y axis positive side, and the Z axis positive side, and the X axis positive side. The second structure analysis side region F2 on the Y axis positive side and the Z axis negative side, the third structure analysis side region F3 on the X axis positive side, the Y axis negative side and the Z axis positive side, and the X axis positive side The fourth structural analysis side region F4 on the Y axis negative side and the Z axis negative side, the fifth structural analysis side region F5 on the X axis negative side, the Y axis positive side and the Z axis positive side, and the X axis negative side The sixth structure analysis side region F6 on the Y axis positive side and the Z axis negative side, the seventh structure analysis side region F7 on the X axis negative side, the Y axis negative side and the Z axis positive side, and the X axis negative side Then, the structure is divided into eight structural analysis side regions including the eighth structural analysis side region F8 on the Y axis negative side and the Z axis negative side (step S53). Thereby, the part comprised by the said boundary condition setting object element in a structural analysis model straddles a plurality (in this embodiment, eight) structure analysis side area | regions.

  After the division, the boundary condition setting target elements are classified into F1 to F8 structure analysis side regions (step S54).

  Next, a space defined by the three-dimensional coordinate axis where the fluid analysis model exists is divided into a plurality of fluid analysis side regions so as to correspond to the plurality of structural analysis side regions (F1 to F8), respectively. In the present embodiment, first, the coordinates of the center of the portion composed of the surface elements in the fluid analysis model (hereinafter referred to as the fluid analysis model center) by the three-dimensional coordinate axis are obtained (step S55). Specifically, the maximum value and the minimum value of the X coordinate are extracted from the center coordinate data of each element of the fluid analysis model by extracting the maximum value and the minimum value of the X coordinate, the Y coordinate, and the Z coordinate, respectively. Is the X coordinate of the center of the fluid analysis model, the average value of the maximum and minimum values of the Y coordinate is the Y coordinate of the center of the fluid analysis model, and the average value of the maximum and minimum values of the Z coordinate. Is the Z coordinate of the center of the fluid analysis model.

  Then, the space where the fluid analysis model exists is a first corresponding to the first structural analysis side region F1 on the X-axis positive side, the Y-axis positive side, and the Z-axis positive side with respect to the center of the fluid analysis model. A fluid analysis side region C1, a second fluid analysis side region C2 corresponding to the second structure analysis side region F2 on the X axis positive side, the Y axis positive side, and the Z axis negative side, the X axis positive side, Y A third fluid analysis side region C3 corresponding to the third structural analysis side region F3 on the negative axis side and the positive Z axis side, and the third fluid analysis side region C3 on the X axis positive side, the Y axis negative side, and the Z axis negative side. A fourth fluid analysis side region C4 corresponding to the four structure analysis side region F4 and a fifth fluid analysis corresponding to the fifth structure analysis side region F5 on the X axis negative side, the Y axis positive side and the Z axis positive side. Side region C5 and a sixth fluid analysis side region C corresponding to the sixth structural analysis side region F6 on the X axis negative side, the Y axis positive side, and the Z axis negative side A seventh fluid analysis side region C7 corresponding to the seventh structural analysis side region F7 on the X axis negative side, the Y axis negative side, and the Z axis positive side, the X axis negative side, the Y axis negative side, and the Z axis The fluid is divided into eight fluid analysis side regions, which are on the negative side of the axis and the eighth fluid analysis side region C8 corresponding to the eighth structure analysis side region F8 (step S56).

  The coordinates of the center of the structural analysis model and the coordinates of the center of the fluid analysis model are basically the same (in this embodiment, the data of the center coordinates of each boundary condition setting target element and each of the fluid analysis model as described above. Since the average value of the maximum value and the minimum value of the center coordinate data of the element is used, there is a possibility of slight deviation), and the structural analysis side region and the fluid analysis side region corresponding to each other are in the above three-dimensional coordinate axes. It will be located in the same part in the defined space.

  After the division, the fluid analysis model elements are classified into C1 to C8 fluid analysis side regions (step S57).

  Next, the element of the fluid analysis model corresponding to the boundary condition setting target element is selected from the elements on the surface of the fluid analysis model in the fluid analysis side area corresponding to the structural analysis side area to which the boundary condition setting target element belongs. Identify. In the present embodiment, first, the element of the fluid analysis model corresponding to the boundary condition setting target element in the first structure analysis side region F1 is specified (steps S58 and S59). That is, the element of the fluid analysis model corresponding to the boundary condition setting target element is specified from the elements on the surface of the fluid analysis model in the first fluid analysis side area C1 corresponding to the first structure analysis side area F1. . Specifically, for each boundary condition setting target element in the first structural analysis side region F1, the coordinate position of the boundary condition setting target element and all the elements on the surface of the fluid analysis model in the first fluid analysis side region C1 Is compared with the coordinate position of the element in the fluid analysis model at the coordinate position closest to the coordinate position of the boundary condition setting target element (that is, in the structure analysis model in the space defined by the three-dimensional coordinate axis). When the fluid analysis model is overlaid on the part corresponding to the internal space, the fluid analysis model surface element in contact with the boundary condition setting target element is selected, and the selected element corresponds to the boundary condition setting target element. Identified as an element of the fluid analysis model.

  Subsequently, the element data (temperature and heat transfer coefficient) of the identified fluid analysis model surface are assigned to each boundary condition setting target element in the first structural analysis side region F1 (step S60). And similarly about the boundary condition setting object element in the next 2nd structural analysis side area | region F2, the element of the fluid analysis model corresponding to the said boundary condition setting object element is specified similarly, 2nd structural analysis side area | region The element data of the specified fluid analysis model surface is assigned to the boundary condition setting target element in F2. This is repeated up to the eighth structural analysis side region F8 (steps S59 to S62), the elements on the surface of the fluid analysis model corresponding to the boundary condition setting target elements in all the structural analysis side regions are specified, and the boundary condition setting is performed. Data of the element on the surface of the identified fluid analysis model is assigned to the target element.

  The above-mentioned data may be added every time an element on the surface of the fluid analysis model is specified, and the elements on the surface of the fluid analysis model corresponding to the boundary condition setting target elements in all the structural analysis side regions are specified. You may do it all together later.

  Next, the data given to the boundary condition setting target element is output in the format for structural analysis in order to take in the input file for heat transfer calculation (or thermal stress calculation) in step S10 (step S63). .

  The structural analysis side region and the fluid analysis side region are not limited to F1 to F8 and C1 to C8, and a portion constituted by boundary condition setting target elements in the structural analysis model is divided into a plurality of structural analysis side regions. As long as it straddles, the number and the shape of the structure analysis side region may be any, and the fluid analysis side region corresponds to the structure analysis side region in the same part in the space defined by the three-dimensional coordinate axes. It only has to be located.

  Here, the case where a structure is a cylinder head of an engine is shown as an example.

  FIG. 4 shows a structural analysis model M1 made of a large number of elements (tetramesh in this example) created for the cylinder head. Reference numeral 1 denotes a portion corresponding to the cooling water inlet to the water jacket. The cooling water inlet is provided on a contact surface of the cylinder head with the cylinder block so that the cooling water flows from the cylinder block to the water jacket. Although not visible in FIG. 4, there is a portion corresponding to the cooling water outlet on the left side surface of FIG. 4 in the structural analysis model M1 (in FIG. 6, the portion corresponding to the cooling water outlet is denoted by reference numeral 2). ing). Thus, the cylinder head has a water jacket as an internal space through which cooling water (fluid) flows, and this water jacket is provided with a cooling water inlet and outlet as an open portion that opens to the outside of the cylinder head. The cooling water flows into and out of the water jacket through the cooling water inlet and outlet.

When extracting the boundary condition setting target element (the element in the portion corresponding to the surface in contact with the water jacket) from the structural analysis model M1, the operator looks at the structural analysis model M1 as shown in FIG. Among all the elements in the portion corresponding to the surface in contact with the water jacket, the elements in the portion corresponding to the end corresponding to the cooling water inlet in the surface in contact with the water jacket, which is a visible element (for example, in FIG. An element E1) shown in FIG. 5 in which a portion corresponding to the cooling water inlet in the structural analysis model is enlarged is set as a reference element. The orientation of the structural analysis model M1 can be changed so that an operator can see the cooling water outlet side, and this corresponds to the end corresponding to the cooling water outlet on the surface in contact with the water jacket. An element in the part can be set as a reference element.

  The reference element set in this way is used as a core, and the elements in the portion corresponding to the surface in contact with the water jacket that are adjacent to each other are automatically extracted as the boundary condition setting target elements. Here, an element in a portion corresponding to the cylinder block contact surface provided with the cooling water inlet (for example, an element E2 shown in FIG. 5) or an element in a portion corresponding to the side surface provided with the cooling water outlet is provided. However, these elements are selected (see step S23 above), but these elements are elements that are pre-designated by the operator and are in a portion corresponding to the outer surface of the cylinder head. It is never extracted. Then, all the elements in the portion corresponding to the surface in contact with the water jacket are extracted, and there is no extracted element (the element (element E2 etc.) in the portion corresponding to the outer surface of the cylinder head is selected). The extraction process ends.

  FIG. 6 shows a portion composed of the extracted boundary condition setting target elements in the structural analysis model M1. Note that FIG. 6 is different from FIG. 4 in the viewing direction, and the portion 2 corresponding to the cooling water outlet is visible.

  FIG. 7 shows a portion composed of the elements on the surface in the fluid analysis model M2 made up of a large number of elements (in this example, hexamesh) created for the cooling water that is the fluid flowing through the water jacket of the cylinder head. ing. 6 and 7, common three-dimensional coordinate axes (X axis, Y axis, and Z axis) are set for the structural analysis model M1 and the fluid analysis model M2.

  In the space defined by the three-dimensional coordinate axis, when the fluid analysis model M2 is superimposed on a portion corresponding to the internal space in the structural analysis model M1, the boundary analysis setting target element is extracted from the structural analysis model M1. The portion and the surface of the fluid analysis model M2 just touch each other. While the number of elements on the surface of the fluid analysis model M2 is about 110,000, the number of boundary condition setting target elements extracted from the structural analysis model M1 is about 80,000. This is because the size of the element of the structural analysis model M1 is larger than the size of the element of the fluid analysis model M2. For this reason, there are a plurality of elements on the surface of the fluid analysis model M2 in contact with one boundary condition setting target element. In this embodiment, one element of the fluid analysis model M2 corresponding to one boundary condition setting target element is one. Only the element (the element at the coordinate position closest to the coordinate position of the boundary condition setting target element) is specified. Even if it does in this way, it will not have a big influence on the result of the heat conduction analysis or thermal stress analysis of a cylinder head, and a big problem will not arise.

  A plurality of elements may be specified as elements of the fluid analysis model M2 corresponding to one boundary condition setting target element. In this case, for example, the element (s) on the surface of the fluid analysis model M2 at a coordinate position within a predetermined distance from the coordinate position of the boundary condition setting target element is used as an element of the fluid analysis model M2 corresponding to the boundary condition setting target element. What is necessary is just to specify and give to the said boundary condition setting object element by averaging the data of these some elements.

  In the present embodiment, when the elements of the fluid analysis model M2 are specified, the coordinate positions of the boundary condition setting target elements are not compared with the coordinate positions of all the elements on the surface of the fluid analysis model M2, but the three-dimensional coordinate axes are not compared. The space in which the structural analysis model M1 and the fluid analysis model M2 exist defined in (1) is divided into eight corresponding structural analysis side regions F1 to F8 and fluid analysis side regions C1 to C8, respectively, and boundary condition setting targets Since the coordinate position of the element and the coordinate position of the surface of the fluid analysis model M2 in the fluid analysis side region corresponding to the structural analysis side region to which the boundary condition setting target element belongs are compared, one boundary condition setting target The number of elements to be compared can be reduced to about 1/8 (110,000 / 8) compared with all elements on the surface of the fluid analysis model M2.

  In specifying the element of the fluid analysis model M2, the coordinate position of the boundary condition setting target element may be compared with the coordinate positions of all the elements on the surface of the fluid analysis model M2, but in this case, one boundary is set. Since the comparison target elements of the condition setting target elements are considerably large, it is preferable to reduce the number of comparison target elements as described above.

Therefore, in this embodiment, it corresponds to a surface in contact with the internal space of the structure in the structural analysis model created for the structure having an open space that opens to the outside and having an internal space through which fluid flows in and out. from all elements in the part, any element in the portion corresponding to the end portion corresponding to the opening in the surface in contact with the internal space, and that personnel are set as the reference element, the control of the computer The calculation unit extracts, as a boundary condition setting target element, an element in a portion corresponding to a surface adjacent to the internal space that is adjacent to the reference element set in the structural analysis model as a core. Therefore, the elements in the part corresponding to the surface in contact with the internal space of the structure in the structural analysis model are sequentially ordered from the outer surface elements in the structural analysis model. Compared with the method of extracting and the like excluding Ri, can be extracted easily and in a short time, the extraction time of the boundary condition setting target element can be greatly shortened.

  Further, when extracting the boundary condition setting target element, the element in the portion corresponding to the surface of the structure adjacent to the reference element or the boundary condition setting target element in the structural analysis model is once selected, and the selected element is Judgment whether or not the element is in the part corresponding to the outer surface of the structure, and extracting the element determined not to be the element in the part corresponding to the outer surface of the structure as the boundary condition setting target element Therefore, it is possible to reliably extract only the elements in the portion corresponding to the surface in contact with the internal space of the structure in the structural analysis model.

  Further, after extracting the boundary condition setting target element, the number of boundary condition setting target elements is counted up, and when the count number stops increasing, the extraction operation of the boundary condition setting target element is stopped. As a result, after extraction of all boundary condition setting target elements has been completed, it is possible to prevent a state in which only elements in the portion corresponding to the outer surface of the structure are selected from continuing, eliminating unnecessary processing. Thus, the processing efficiency can be improved.

  The present invention relates to a structural analysis model created for a structure having an internal space in which an open portion that opens to the outside and fluid flows in and out through the open portion, and data of the fluid analysis model created for the fluid in the internal space Is useful as a boundary condition setting method for structural analysis models.

It is a flowchart which shows the operation | movement procedure in the case of performing the heat-conduction analysis and the thermal-stress analysis of the structure which has the open part which opens to the exterior, and has an internal space where a fluid flows in and out through this open part. It is a flowchart which shows the detailed procedure of extraction of a boundary condition setting object element. It is a flowchart which shows the detailed procedure of a data mapping. It is a perspective view which shows the structural analysis model created about the cylinder head. It is a figure which expands and shows the part corresponded to the cooling water inlet in the structural analysis model of FIG. FIG. 5 is a perspective view showing a part composed of boundary condition setting target elements in the structural analysis model of FIG. 4. It is a perspective view which shows the part comprised by the element in the surface in a fluid analysis model.

1 part corresponding to the cooling water inlet (open part) in the structural analysis model 2 part corresponding to the cooling water outlet (open part) in the structural analysis model E1 end corresponding to the cooling water inlet on the surface in contact with the water jacket in the structural analysis model is a portion corresponding to the cylinder head outer surface of an element E2 structural analysis model in a portion corresponding to the section element

Claims (3)

Corresponding to the surface in contact with the internal space of the structure in a structural analysis model made up of a number of elements, created for a structure having an internal space in which an open portion that opens to the outside is provided and fluid flows in and out through the open portion A computer that sets , as boundary conditions, fluid analysis model data composed of a number of elements created for the fluid in the internal space in order to perform heat transfer calculation or stress calculation of the structure on each element in the part The boundary condition setting method of the structural analysis model by
The computer includes an arithmetic processing unit that performs arithmetic processing, and a surface on which the operator touches the internal space out of all elements in a portion corresponding to the surface that touches the internal space of the structure in the structural analysis model . Reference element input means for setting an arbitrary element in a portion corresponding to the end corresponding to the open portion as a reference element,
The arithmetic processing unit sets a boundary condition for an element in a portion corresponding to the surface adjacent to the internal space, which is adjacent to the reference element set by the reference element input unit in the structural analysis model. A boundary condition setting target element extraction step for extracting as a target element;
For all the boundary condition setting target elements extracted in the boundary condition setting target element extraction step including the reference element by the arithmetic processing unit , element data of the fluid analysis model corresponding to the boundary condition setting target element A boundary condition setting method for a structural analysis model, comprising: a boundary condition setting step for setting as a boundary condition. In the boundary condition setting method of the structural analysis model according to claim 1,
The computer further includes an outer surface element input means for an operator to specify an element in a portion corresponding to the outer surface of the structure in the structural analysis model,
The boundary condition setting target element extraction step is:
A selection step in which the arithmetic processing unit selects an element in a portion corresponding to the surface of the structure adjacent to the reference element or the extracted boundary condition setting target element in the structural analysis model;
A determination step in which the arithmetic processing unit determines whether the selected element is an element in a portion corresponding to the outer surface of the structure specified by the outer surface element input unit ;
An extraction step for extracting, as the boundary condition setting target element, an element determined by the calculation processing unit as not being an element in a portion corresponding to the outer surface of the structure in the determination step, A boundary condition setting method for a structural analysis model, wherein the step, the determination step, and the extraction step are repeated in this order. In the boundary condition setting method of the structural analysis model according to claim 2,
The boundary condition setting target element extraction step further includes a counting step in which the arithmetic processing unit counts up the number of boundary condition setting target elements after the extraction step,
The structural processing model boundary condition setting method, wherein the arithmetic processing unit stops the boundary condition setting target element extraction step when the count number in the counting step stops increasing.

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