JP7348127B2 - A method for analyzing the fracture stress of a honeycomb structure, a method for analyzing the Young's modulus of the plugging material of the plugged portion of the honeycomb structure, and a method for analyzing the stress on the end face of the honeycomb structure. - Google Patents

Description

The present invention relates to a method of analyzing fracture stress of a honeycomb structure, a method of analyzing Young's modulus of a plugging material of a plugged portion of a honeycomb structure, and a method of analyzing stress of an end face of a honeycomb structure.

Conventionally, honeycomb structures have been used in catalyst carriers such as catalyst carriers for automobile exhaust gas purification, diesel engine exhaust gas filters, and the like. Conventionally, thermal stress analysis has been performed to elucidate the failure mechanism of honeycomb structures and predict the occurrence of cracks. Patent Document 1 describes a method for estimating the maximum tensile stress of a honeycomb structure.

JP 2019-144765 Publication

Honeycomb structures used in gasoline particulate filters (GPF), diesel particulate filters (DPF), and the like have plugged portions on their end faces. In this way, when performing thermal stress analysis of a honeycomb structure that has plugged parts on the end face, it is difficult to perform an accurate analysis using only the physical property values (strength, Young's modulus) of the honeycomb base material. In addition to the physical properties of the plugging material, information on the physical properties of the plugging material in the plugged portion and the honeycomb base material in the vicinity of the plugging material is required.

As there is no established thermal stress analysis method for honeycomb structures with plugged parts on the end faces, we measured the test piece with the plugged material solidified and then measured only the honeycomb base material. It is conceivable to conduct an analysis using the physical properties obtained. Here, in the analysis method, the plugging material and the honeycomb base material are measured separately. However, as a result of the inventor's study, it was found that the actual plugging material is filled into the cells on the end face of the honeycomb base material, and some of the plugging material seeps into the partition walls of the honeycomb base material that constitute the cells. ,It became clear. In particular, when the partition walls of the honeycomb base material contain many pores, the amount of penetration of the plugging material also increases.

The above-mentioned thermal stress analysis method for a honeycomb structure having plugged parts on the end face did not take into account the permeation of the plugging material into the partition walls of the honeycomb base material, which had not been noticed before. , results were obtained that were significantly different from actual honeycomb structures with cracks and other fractures, and the analysis accuracy was low.

In particular, in honeycomb base materials, the end face with plugged parts is a place where cracks are likely to occur when the honeycomb structure is used for GPF or DPF, so there is a desire to analyze fracture stress more accurately. be.

In addition, in the above-mentioned thermal stress analysis method for a honeycomb structure having plugged parts on the end face, the plugging material and the honeycomb base material are measured separately, but the actual plugging material is , filled in the cells of the honeycomb base material. Therefore, if it is possible to accurately analyze the Young's modulus of the plugging material in the plugged portion when it is filled into a honeycomb structure, it is possible to analyze the thermal stress of the honeycomb structure with more accuracy. .

The present invention was created in view of the above circumstances, and provides a method for analyzing the fracture stress of a honeycomb structure, which can improve the analysis accuracy, and a Young's modulus of the plugging material for the plugged portions of the honeycomb structure. An object of the present invention is to provide an analysis method and a method for analyzing stress on an end face of a honeycomb structure.

The above problem is solved by the present invention described below, and the present invention is specified as follows.
(1) A partition wall that partitions a plurality of cells penetrating from one end surface to the other end surface to form a flow path, and an open end portion on the one end surface side of a predetermined cell and an open end portion on the one end surface side of the predetermined cell and the opening end portion of the remaining cell. A method for analyzing fracture stress of a columnar honeycomb structure, the method comprising: a plugging portion for plugging an open end on the other end surface side;
specifying a test area of a predetermined size that partially includes cells having the plugged portions from the end face having the plugged portions;
In the test area, performing the following (a) or (b);
(a) removing 80% or more of the plugging portion from each cell from the test area, and then cutting out the test area to form a test piece P _a ;
(b) Cutting out the test region, and then removing 80% or more of the plugged portions per cell from the cut out object to obtain a test piece P _a ;
performing a predetermined bending test on the test piece P _a from which the plugged portions have been removed, and obtaining an actual value of the breaking load of the test piece P _a ;
Using the measured value of the breaking load of the test piece P _a and the arbitrarily set value of the Young's modulus of the plugging material of the plugged portion, analysis was performed using the finite element method, and the plugging obtaining an estimated value L _a of the fracture stress of the partition wall constituting the cell near the cell;
A method for analyzing the fracture stress of a honeycomb structure with
(2) Obtaining an estimated value L _a of the fracture stress of the partition wall constituting the cell near the plugged portion by the method described in (1);
In the honeycomb structure according to (1), a region having the same size as the test region, which partially includes cells having the plugged portions, is specified and cut out from the end face having the plugged portions. , a step of forming a test piece P _b ;
A step of performing a bending test similar to the bending test described in (1) on the test piece P _b to obtain an actual value of the breaking load of the test piece P _b ;
Using the measured value of the fracture load of the test piece P _b and the value of the Young's modulus of the plugging material of the plurality of plugged parts, an analysis is performed using the finite element method, and the estimated fracture stress - eye a step of creating a graph of Young's modulus of the encapsulant;
In the graph of the estimated breaking stress vs. Young's modulus of the plugging material, the Young's modulus Y of the plugging material of the plugged portion when the estimated value L _a of the breaking stress matches the estimated breaking stress. a step of obtaining _b ;
A method for analyzing the Young's modulus of a plugging material in the plugged parts of a honeycomb structure.
(3) Obtaining the Young's modulus Y _b of the plugging material of the plugged portion by the method described in (2);
Young's modulus Y _b of the plugging material of the plugged portions, Young's modulus of the partition walls, thermal expansion coefficient of the partition walls of the honeycomb structure, and thermal expansion coefficient of the plugging material of the plugged portions. A process of performing analysis using the finite element method and estimating the stress on the end face of the honeycomb structure,
A method for analyzing stress on the end face of a honeycomb structure with

According to the present invention, a method of analyzing fracture stress of a honeycomb structure, a method of analyzing Young's modulus of a plugging material of a plugged portion of a honeycomb structure, and a method of analyzing the Young's modulus of a plugging material of a plugged portion of a honeycomb structure, which can improve analysis accuracy, and a method of analyzing the Young's modulus of a plugging material of a plugged portion of a honeycomb structure, and A stress analysis method can be provided.

FIG. 2 is a schematic external view of a columnar honeycomb structure to be analyzed in an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view perpendicular to the extending direction of cells of a columnar honeycomb structure, each of which is an analysis target, in an embodiment of the invention. FIG. 2 is a diagram schematically showing a rectangular parallelepiped-shaped test area specified on the end face of the honeycomb structure. FIG. 2 is a schematic diagram showing a state in which plugging portions are removed from a test area (or test piece P _a ). FIG. 2 is a diagram schematically illustrating an example of a bending test method. This is an example of a graph of estimated fracture stress versus Young's modulus of a plugging material.

Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. It is understood that the present invention is not limited to the following embodiments, and that design changes, improvements, etc. may be made as appropriate based on the common knowledge of those skilled in the art without departing from the spirit of the present invention. Should.

(1. Honeycomb structure)
FIG. 1 shows a method of analyzing fracture stress of a honeycomb structure, a method of analyzing Young's modulus of a plugging material of a plugged portion of a honeycomb structure, and a method of analyzing stress of an end face of a honeycomb structure, according to an embodiment of the present invention. 2 shows a schematic external view of a columnar honeycomb structure 10 that is the target of each analysis. FIG. 2 shows a method of analyzing fracture stress of a honeycomb structure, a method of analyzing Young's modulus of a plugging material of a plugged portion of a honeycomb structure, and a method of analyzing stress of an end face of a honeycomb structure, according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view perpendicular to the extending direction of cells 15 of the columnar honeycomb structure 10, which is the target of each analysis. The honeycomb structure 10 has an outer peripheral wall 11 and a partition wall 12 that is disposed inside the outer peripheral wall 11 and partitions and forms a plurality of cells 15 that penetrate from one end face to the other end face and form a flow path. .

The outer shape of the honeycomb structure 10 is not particularly limited as long as it is columnar. For example, the outer shape of the honeycomb structure 10 is columnar with a circular bottom (cylindrical shape), columnar with an oval bottom, polygonal (quadrilateral, pentagonal, hexagonal, heptagonal, etc.) with a bottom surface. The shape may be a columnar shape such as an octagonal shape, etc. Further, the size of the honeycomb structure 10 is not particularly limited, but the area of the bottom surface may be 2000 to 20000 mm ² , for example.

The honeycomb structure 10 is made of ceramics. Examples of the ceramics constituting the honeycomb structure 10 include, but are not limited to, oxide ceramics such as alumina, mullite, zirconia, and cordierite, and non-oxide ceramics such as silicon carbide, silicon nitride, and aluminum nitride. be able to. Further, a silicon carbide-metal silicon composite material, a silicon carbide/graphite composite material, etc. can also be used.

The shape of the cell 15 in a cross section perpendicular to the stretching direction of the cell 15 is not limited, but may be quadrilateral, hexagonal, octagonal, or a combination thereof.

The thickness of the partition walls 12 that define the cells 15 may be, but not limited to, 0.1 to 0.35 mm. In the present invention, the thickness of the partition wall 12 is defined as the length of the portion that passes through the partition wall 12 among the line segments connecting the centers of gravity of adjacent cells 15 in a cross section perpendicular to the extending direction of the cells 15.

The honeycomb structure 10 may have a cell density of 40 to 150 cells/cm ² in a cross section perpendicular to the flow path direction of the cells 15. The cell density is a value obtained by dividing the number of cells by the area of one bottom surface portion of the honeycomb structure 10 excluding the outer wall 12 portion.

The thickness of the outer peripheral wall 11 of the honeycomb structure 10 may be, but not limited to, 0.1 mm to 1.0 mm. Here, the thickness of the outer circumferential wall 11 is determined in the normal direction to the tangent to the outer circumferential wall 11 at the measurement point when the point of the outer circumferential wall 11 whose thickness is to be measured is observed in a cross section perpendicular to the stretching direction of the cells 15. is defined as the thickness of

The partition wall 12 can be porous. The porosity of the partition wall 12 may be, but not limited to, 35 to 60%. The porosity is a value measured using a mercury porosimeter.

The average pore diameter of the partition walls 12 of the honeycomb structure 10 may be, but not limited to, 2 to 15 μm. The average pore diameter is a value measured using a mercury porosimeter.

The honeycomb structure 10 has a plugging portion that plugs the open ends on one end surface side of a predetermined cell 15 and the open ends on the other end surface side of the remaining cells 15. Although not limited to this, as shown in FIG. 2, the honeycomb structure 10 has a plurality of cells A that are open on one end surface and have plugged portions 19 on the other end surface, and the cells A are arranged alternately. It may be provided with a plurality of cells B having the other end face open and having plugging portions 19 on one end face. Cells A and B are alternately arranged adjacent to each other with partition walls 12 in between, and both end faces form a checkered pattern. The number, arrangement, shape, etc. of cells A and B are not limited and can be designed as appropriate.

(2. Analysis method of fracture stress of honeycomb structure)
Next, a method for analyzing fracture stress of a honeycomb structure according to an embodiment of the present invention will be described. In the method for analyzing the fracture stress of a honeycomb structure according to the embodiment of the present invention, first, a test of a predetermined size including cells 15 partially having plugged portions 19 is performed from an end face having plugged portions 19. Specify the area.

FIG. 3 schematically shows a rectangular parallelepiped-shaped test area 16 designated on the end face of the honeycomb structure 10. Since the test area 16 is cut out from the honeycomb structure 10 to form the test piece P _a as described later, it is specified to have the same shape and size as the desired test piece P _a . The size and shape of the test area 16 are not particularly limited; It is preferably a rectangular parallelepiped with a width of 30 to 100 mm and a thickness of 3 to 10 mm. Further, it is preferable that the test area 16 (that is, the thickness of the test piece P _a ) and the depth of the plugging portion 19 be set to the same value.

Next, in the test area 16, the following (a) or (b) is performed.
(a) 80% or more of the plugging portions 19 are removed per cell from the test region 16, and then the test region 16 is cut out to form a test piece P _a .
(b) Cut out the test region 16, and then remove 80% or more of the plugged portions 19 per cell from the cut out object to obtain a test piece P _a .
The test piece P _a can be cut out from the honeycomb structure 10 using, for example, a diamond cutter. Furthermore, the plugging portions 19 can be removed using a drill or the like.

FIG. 4 is a schematic diagram showing how the plugging portions 19 are removed from the test area 16 (or test piece P _a ). As shown in FIG. 4, when attempting to remove only the plugging portions 19 with a drill or the like from a state in which the plugging portions 19 are filled in the end face portions of the cells 15, on the surface of the partition walls of the cells 15, There is a tendency for the plugged portions 19 that could not be completely removed to remain. In both (a) and (b) above, the remaining amount of the plugged portions 19 is less than 20% by volume, that is, the plugged portions 19 are removed based on the total volume of the plugged portions 19 before removal. It is sufficient to remove 80% by volume or more. Furthermore, in order to further improve the analysis accuracy, it is preferable to use a test piece P _a of the honeycomb structure 10 in which the plugged portions 19 are eliminated as much as possible for the bending test described below. From this viewpoint, it is preferable to remove 85% by volume or more of the plugging portions 19, more preferably to remove 90% by volume or more, and even more preferably to substantially remove 100% by volume.

Next, a predetermined bending test is performed on the test piece P _a from which the plugged portions have been removed, and an actual value of the breaking load of the test piece P _a is obtained. Any known bending test method and bending test device can be used, but for example, the bending test method is preferably conducted in accordance with the method standardized by JIS R 1664, and the bending test device is INSTRON. An example of this is the 3366 dual-column tabletop tester manufactured by Co., Ltd. FIG. 5 is a diagram schematically explaining an example of the bending test method. As shown in FIG. 5, the load for the bending test is applied in the thickness direction of the test piece P _a . At this time, two cylindrical indenters 21 are placed above the test piece P _a at a predetermined interval. Furthermore, two cylindrical support stands 22 are arranged below the test piece P _a with a predetermined interval. In this state, a load is applied equally to the two indenters 21. The load is gradually increased at a constant speed. At this time, the load (N) and the bending deflection (mm) of the test piece P _a are measured, and the maximum load until the test piece breaks is taken as the actual value of the breaking load of the test piece P _a .

Next, using the measured value of the breaking load of the test piece P _a and the arbitrarily set value of the Young's modulus of the plugging material of the plugged portion 19, an analysis is performed using the finite element method, and the plugging An estimated value L _a of the breaking stress of the partition wall 12 constituting the cell 15 near the stop portion 19 is obtained. The Young's modulus of the plugging material of the plugging portions 19 can be set arbitrarily. This is because, although the details will be described later, the estimated value L _a of the fracture stress does not change significantly even if the Young's modulus of the plugging material is changed. The Young's modulus of the plugging material of the plugging portions 19 can be set, for example, in the range of 1×10 ³ to 1×10 ⁷ N/m ² .

As a specific procedure for the analysis using the finite element method, first, a model of the test piece P _a from which the plugged portions have been removed is created using structural analysis software that is capable of analysis using the finite element method. Examples of structural analysis software that can perform analysis using the finite element method include ANSYS (manufactured by ANSYS, Inc.), Abaqus (manufactured by Dassault Systèmes), and the like. In addition, when creating a model on structural analysis software, the number of element divisions can be found, for example, in paragraph 0030 of JP-A No. 2005-242679, and the element size can be determined, for example, in paragraph 0050 of the publication. You can refer to it. Next, in performing the analysis, the partition walls of the honeycomb base material, the plugging material, their respective Poisson's ratios, and Young's modulus (the Young's modulus of the plugging material is an arbitrary value as described above) are set. Then, by simulating the bending test method, the position of the support pin is constrained, and the breaking load obtained by the bending test method is applied to the position of the load pin, and analysis is performed. For example, when applying a load in the Z-axis direction, restraint is applied in the Z-axis direction. From the analysis results, the maximum stress occurring in the partition walls 12 constituting the cells 15 in the vicinity of the plugged portions 19 is set as the estimated value L _a of the breaking stress.

According to the method for analyzing the fracture stress of a honeycomb structure according to the embodiment of the present invention, since the analysis is performed on the partition wall of the honeycomb base material in which the plugging material has penetrated, the analysis of the fracture stress of the actual honeycomb structure is performed. Good analysis accuracy close to the results can be obtained. In particular, in a honeycomb base material, the end face having plugged parts is a place where cracks are likely to occur when the honeycomb structure is used for GPF or DPF, etc., but the fracture stress of the honeycomb structure in the embodiment of the invention According to the analysis method, the fracture stress can be analyzed more accurately.

(3. Method for analyzing Young's modulus of plugging material in plugged portions of honeycomb structure)
Next, a method for analyzing the Young's modulus of the plugging material of the plugged portions of the honeycomb structure according to the embodiment of the present invention will be described. The method for analyzing the Young's modulus of the plugging material for the plugged portions of the honeycomb structure in the embodiment of the present invention is to first analyze the fracture stress of the honeycomb structure in the embodiment of the present invention described above. An estimated value L _a of the breaking stress of the partition wall 12 constituting the cell 15 near the stop portion 19 is obtained.

Next, in the honeycomb structure 10, a test area 26 having the same size as the test area 16, including the cells 15 partially having the plugged parts 19, is specified and cut out from the end face having the plugged parts 19. This is called test piece P _b . Subsequently, as shown in FIG. 5, the test piece P _b was subjected to a bending test similar to the bending test described above in the method for analyzing fracture stress of a honeycomb structure according to the embodiment of the present invention, and the test piece P _b was tested for fracture. Obtain the actual measured value of the load.

Here, in the method for analyzing the Young's modulus of the plugging material of the plugged portions of the honeycomb structure in the embodiment of the present invention, the The Young's modulus of the plugging material is analyzed using the estimated value L _a of the fracture stress of the partition wall 12 constituting the cell 15 near the sealing part 19, and the test area 26 is set to the same size as the test area 16. It is important to specify this in order to accurately implement this analysis method. Although it is preferable that the size of the test area 26 completely match the size of the test area 16, there may be a deviation of several millimeters. That is, it is sufficient to specify a test area 26 that is "approximately the same size" as the test area 16. For example, if the test areas 16 and 26 are each shaped like a rectangular parallelepiped, they can be considered to have substantially the same size as long as the height, width, and length differ within a few millimeters.

Next, using the measured value of the fracture load of the test piece P _b and the value of the Young's modulus of the plugging material of the plurality of plugged parts, analysis was performed using the finite element method, and the estimated fracture stress - Create a graph of the Young's modulus of the plugging material. An example of the graph of the obtained estimated fracture stress versus Young's modulus of the plugging material is shown in FIG.

As a specific procedure for analysis using the finite element method, first, a model of the test piece P _b is created using structural analysis software that is capable of analysis using the finite element method. Examples of structural analysis software that can perform analysis using the finite element method include those similar to those described above. Furthermore, when creating a model on the structural analysis software, the number of element divisions and element size can be determined with reference to the above. Next, in performing the analysis, the partition walls of the honeycomb base material, the plugging material, their respective Poisson's ratios, and Young's modulus (the Young's modulus of the plugging material is an arbitrary value as described above) are set. Then, by simulating the bending test method, the position of the support pin is constrained, and the breaking load obtained by the bending test method is applied to the position of the load pin, and analysis is performed. For example, when applying a load in the Z-axis direction, restraint is applied in the Z-axis direction. Then, from the analysis results, the maximum stress occurring in the partition walls 12 constituting the cells 15 near the plugged portions 19 is set as the estimated breaking stress. By setting a plurality of Young's modulus of the plugging material and repeating the same analysis to obtain and plot the estimated breaking stress, a graph of estimated breaking stress vs. Young's modulus of the plugging material shown in FIG. 6 is created.

Next, as shown in FIG. 6, in the graph of estimated fracture stress vs. Young's modulus of the plugging material, when the estimated value L _a of the fracture stress matches the estimated fracture stress, Obtain the Young's modulus Y _b of the retaining material. Here, the estimated value L _a of the fracture stress does not change significantly even if the Young's modulus of the plugging material is changed, and the fracture (crack) on the end face of the honeycomb structure 10 occurs at the partition wall 12. This does not occur in the plugged areas. Therefore, as described above, there is no problem even if the estimated value L _a of the breaking stress is made to match the estimated breaking stress.

According to the method for analyzing the Young's modulus of the plugging material of the plugged portions of the honeycomb structure in the embodiment of the present invention, the plugging of the plugged portions 19 in the state filled in the honeycomb structure 10 is performed. The Young's modulus of materials can be analyzed with high accuracy.

(4. Analysis method of stress on end face of honeycomb structure)
Next, a method for analyzing stress on the end face of a honeycomb structure in an embodiment of the present invention will be described. The method for analyzing the stress on the end face of the honeycomb structure in the embodiment of the present invention is as follows: The Young's modulus Y _b of the plugging material of the sealing portion 19 is obtained. Note that when obtaining the Young's modulus Y _b of the plugging material of the plugged portions 19, the cells near the plugged portions 19 are It is necessary to obtain an estimated value L _a of the fracture stress of the partition wall 12 that constitutes the partition wall 15 .

Next, in addition to the obtained Young's modulus Y _b of the plugging material of the plugged portions, the Young's modulus of the partition walls 12 , the coefficient of thermal expansion of the partition walls 12 of the honeycomb structure 10 , and the coefficient of thermal expansion of the plugged portions 19 Using the coefficient of thermal expansion of the plugging material, analysis is performed using the finite element method to estimate the stress on the end face of the honeycomb structure 10. The stress on the end face of the honeycomb structure 10 is analyzed, for example, by the finite element method when the honeycomb structure 10 is exposed to a high temperature of 100 to 1300°C.

As a specific procedure for analysis using the finite element method, first, a model of the entire honeycomb base material is created using structural analysis software that can perform analysis using the finite element method. Examples of structural analysis software that can perform analysis using the finite element method include those similar to those described above. When creating a model of the entire honeycomb base material, for example, the description in paragraph 0018 of JP 2019-144765 A can be referred to. Next, we set the partition walls and plugging material of the honeycomb base material, their respective Poisson's ratios, Young's modulus, coefficient of thermal expansion, and temperature distribution of the honeycomb structure, performed finite element analysis to calculate stress, and Find the maximum principal stress on the end face of the body. To set the temperature distribution of the honeycomb structure, temperatures are given to each node of the model (finite element model) from temperature distribution data under actual usage conditions. As a method for determining the maximum principal stress on the end face of a honeycomb structure by finite element analysis, it can be determined according to the known method described in, for example, JP-A No. 2005-242679, JP-A No. 2005-241448, etc. .

Previously, the physical property value (Young's modulus) of the plugging material was obtained only from the plugging material (bulk material), so if it differs from the plugging material existing on the end face of the honeycomb structure, it could be The inventors are thinking. If the stress analysis method of the end face of a honeycomb structure according to the embodiment of the present invention is adopted, the honeycomb structure 10 in which the plugging material has penetrated into the partition walls of the honeycomb base material, and the honeycomb structure 10 filled with the plugging material. The Young's modulus of the plugging material of the plugged portions 19 in this state can be analyzed with high accuracy. The inventors believe that the fracture stress of the honeycomb structure 10 can be analyzed with higher accuracy because physical property values close to those of the plugging material existing on the end face of the honeycomb structure are obtained. I'm guessing.

EXAMPLES Hereinafter, examples will be illustrated to better understand the present invention and its advantages, but the present invention is not limited to the examples.

<Example 1>
(1. Preparation of honeycomb structure)
A rectangular cordierite honeycomb structure with length 118 mm, width 118 mm, length 130 mm, partition wall thickness 0.2 mm, and distance between partition walls approximately 1.5 mm was prepared, and at both ends of the cells of the honeycomb structure, Plugging portions having a thickness of 6 mm and using cordierite as a plugging material are provided so that both end faces of the honeycomb structure form a checkered pattern.

(2. Analysis of fracture stress of honeycomb structure)
Next, a test area including cells partially having plugged portions was designated from the end face of the honeycomb structure. The test area has a rectangular parallelepiped shape with a plane corresponding to the end face having the plugged portion measuring 8 mm in length x 70 mm in width and 6 mm in thickness. Further, the thickness of the test area (that is, the thickness of the test piece P _a described later) and the depth of the plugging portion are assumed to be the same value.

Next, approximately 80% by volume of each plugged portion per cell is removed from the test area using a drill, and then the test area is cut out using a diamond cutter to form a test piece P _a .

Next, the test piece P _a from which the plugged portions were removed was subjected to a bending test according to the method specified in JIS R 1664 using a 3366 dual column desktop testing machine manufactured by INSTRON as a bending test device. I do. At this time, the load (N) and the bending deflection (mm) of the test piece P _a are measured, and the maximum load until the test piece breaks is taken as the actual value of the breaking load of the test piece P _a .

Next, using the measured value of the breaking load of the test piece P _a and the value of the Young's modulus of the plugging material in the plugged portion, analysis was performed using the finite element method, and the cells near the plugged portion were analyzed. Obtain the estimated value L _a of the fracture stress of the constituent partition walls. As a specific procedure for analysis using the finite element method, first, the test piece P _a from which the plugged portions have been removed is analyzed using ANSYS (manufactured by ANSYS, Inc.), which is a structural analysis software that can perform analysis using the finite element method. ) to create a model. In addition, when creating a model on structural analysis software, the number of element divisions should be 2 or more in the thickness direction of the partition wall, with reference to the description in paragraph 0030 of JP 2005-242679A, and the number of element divisions should be 2 or more in the thickness direction of the partition wall. The number of element divisions of the section is 2 or more.

Next, in performing the analysis, the Poisson's ratio and Young's modulus of the partition walls of the honeycomb base material and the plugging material are set. Then, by simulating the bending test method, the support pins are restrained in the Z-axis direction, and the breaking load obtained by the bending test method is applied to the load pin position in the Z-axis direction, and analysis is performed. Then, from the analysis results, the maximum stress occurring in the partition walls constituting the cells in the vicinity of the plugged portions is set as the estimated value L _a of the breaking stress.
The estimated value of fracture stress L _a obtained from the above analysis results is different from the value of fracture stress obtained by analysis based on the physical property values of a honeycomb base material without conventional plugging material. Ta.

(3. Analysis of Young's modulus of the plugging material of the plugged portion of the honeycomb structure)
The above honeycomb structure is prepared again. Next, from the end face of the honeycomb structure having the plugged portions, a test region including cells that partially have plugged portions is designated and cut out with a diamond cutter to obtain a test piece P _b . Test piece P _b has the same size as test piece P _a . Subsequently, a bending test similar to the above-described bending test is performed on the test piece P _b to obtain an actual value of the breaking load of the test piece P _b .

Next, using the measured value of the breaking load of the test piece P _b and the value of the Young's modulus of the plugging material of the plurality of plugged parts, an analysis was performed using the finite element method, and the result was as shown in FIG. 6. Create a graph of estimated fracture stress vs. Young's modulus of plugging material.

The specific procedure for the analysis using the finite element method is to use the same structural analysis software as that used in the analysis using the finite element method in the above-mentioned "analysis of fracture stress of a honeycomb structure," and to follow the same procedure. Regarding the element division of the plugging portion, refer to the description in paragraph 0030 of JP-A No. 2005-242679. Separate. The number of element divisions in the thickness direction of the partition wall is two or more, and the number of element divisions in the intersecting curved surface portion of the partition wall is two or more. Then, from the analysis results, the maximum stress occurring in the partition walls constituting the cells near the plugged portions is set as the estimated breaking stress. By setting a plurality of Young's modulus of the plugging material and repeating the same analysis to obtain and plot the estimated breaking stress, a graph of estimated breaking stress vs. Young's modulus of the plugging material shown in FIG. 6 is created.

Next, in the graph of estimated breaking stress vs. Young's modulus of plugging material shown in FIG. 6, when the estimated value L _a of breaking stress matches the estimated breaking stress, Obtain Young's modulus Y _b .
The Young's modulus Y _b of the plugging material in the plugged portion obtained from the above analysis results is the Young's modulus Y b obtained by analysis based on the physical property values of a bulk body made by solidifying only the conventional plugging material. It was different from the value.

(4. Analysis of stress on end face of honeycomb structure)
In addition to the Young's modulus Y _b of the plugging material in the plugged portions obtained, the Young's modulus of the partition walls, the coefficient of thermal expansion of the partition walls of the honeycomb structure, and the thermal expansion of the plugging material in the plugged portions. Using the coefficients, perform analysis using the finite element method to estimate the stress at the end face of the honeycomb structure. The stress on the end face of the honeycomb structure is analyzed using the finite element method when the honeycomb structure is exposed to a high temperature of 1000°C.

The specific steps for analysis using the finite element method are as follows: First, for the entire honeycomb base material, use the same structural analysis software as that used in the finite element method analysis in "Analysis of fracture stress in honeycomb structures" mentioned above. Create a model using The finite element model of the entire honeycomb base material is a partial finite element model divided into quarters so that each part has the same shape.

Next, the Poisson's ratio of the partition walls and the plugging material of the honeycomb base material, the Young's modulus of the partition wall, the Young's modulus Y _b of the plugging material of the plugged portion, and the coefficient of thermal expansion are set, and the temperature distribution of the honeycomb structure is , perform finite element analysis to calculate stress, and find the maximum principal stress at the end face of the honeycomb structure. To set the temperature distribution of the honeycomb structure, temperatures are given to each node of the model (finite element model) from temperature distribution data under actual usage conditions. The maximum principal stress of the end face of the honeycomb structure is determined by finite element analysis in accordance with the method described in JP-A No. 2005-242679.

10 Honeycomb structure 11 Peripheral wall 12 Partition wall 15 Cells 16, 26 Test area 19 Plugging portion 21 Indenter 22 Support stand

Claims (3)

A partition wall that partitions a plurality of cells penetrating from one end face to the other end face to form a flow path, and an open end on the one end face side of a predetermined cell and the other end face of the remaining cells. A method for analyzing fracture stress of a columnar honeycomb structure, the method comprising: a plugging portion for plugging a side opening end;
specifying a test area of a predetermined size that partially includes cells having the plugged portions from the end face having the plugged portions;
In the test area, performing the following (a) or (b);
(a) removing 80% or more of the plugging portion from each cell from the test area, and then cutting out the test area to form a test piece P _a ;
(b) Cutting out the test region, and then removing 80% or more of the plugged portions per cell from the cut out object to obtain a test piece P _a ;
performing a predetermined bending test on the test piece P _a from which the plugged portions have been removed, and obtaining an actual value of the breaking load of the test piece P _a ;
Using the measured value of the breaking load of the test piece P _a and the arbitrarily set value of the Young's modulus of the plugging material of the plugged portion, analysis was performed using the finite element method, and the plugging obtaining an estimated value L _a of the fracture stress of the partition wall constituting the cell near the cell;
A method for analyzing the fracture stress of a honeycomb structure with obtaining an estimated value L _a of the fracture stress of a partition wall constituting a cell near the plugged portion by the method according to claim 1;
In the honeycomb structure according to claim 1, an area having the same size as the test area, which partially includes cells having the plugged parts, is specified and cut out from the end face having the plugged parts. , a step of forming a test piece P _b ;
A step of performing a bending test similar to the bending test according to claim 1 on the test piece P _b to obtain a measured value of the breaking load of the test piece P _b ;
Using the measured value of the fracture load of the test piece P _b and the value of the Young's modulus of the plugging material of the plurality of plugged parts, an analysis is performed using the finite element method, and the estimated fracture stress - eye a step of creating a graph of Young's modulus of the encapsulant;
In the graph of the estimated breaking stress vs. Young's modulus of the plugging material, the Young's modulus Y of the plugging material of the plugged portion when the estimated value L _a of the breaking stress matches the estimated breaking stress. a step of obtaining _b ;
A method for analyzing the Young's modulus of a plugging material in the plugged parts of a honeycomb structure. Obtaining Young's modulus Y _b of the plugging material of the plugging portion by the method according to claim 2;
Young's modulus Y _b of the plugging material of the plugged portions, Young's modulus of the partition walls, thermal expansion coefficient of the partition walls of the honeycomb structure, and thermal expansion coefficient of the plugging material of the plugged portions. A process of performing analysis using the finite element method and estimating the stress on the end face of the honeycomb structure,
A method for analyzing stress on the end face of a honeycomb structure with