JP7469653B2 - Evaluation device, evaluation method, and program - Google Patents

Description

The present invention relates to a structural member evaluation device, evaluation method, and program.

A bogie frame for railway vehicles (hereafter abbreviated as bogie frame) is a structural member that supports the car body as well as various bogie parts such as wheels, axles, main motors, drive units, and suspension parts. When the railway vehicle is running, loads are transmitted from the various bogie parts to the bogie frame. For this reason, the bogie frame must have sufficient strength and durability to withstand these loads.

Therefore, various methods have been proposed to evaluate the strength of the bogie frame. For example, in the method of evaluating the strength of the bogie frame disclosed in Patent Document 1, the strength of the bogie frame is evaluated using an FEM model of the bogie frame.

Specifically, in the strength evaluation method of Patent Document 1, a virtual strain gauge is defined for each of the multiple nodes on the surface of the FEM model, and the stress that occurs when a load is applied is calculated for each node. Then, the safety factor at each node is calculated based on a previously prepared endurance limit diagram and the stress calculated for each node.

JP 2005-190242 A

The strength of the bogie frame needs to be appropriately evaluated according to the material classification (classification indicating the type of material: SM400, SM400A, SM490, SM490A, etc.) and specification classification (classification indicating the state of each part: base material, as welded, polished finish, etc.) of each part of the bogie frame. In this regard, in the method of Patent Document 1, a durability limit diagram is prepared for each specification classification (base material, as welded, and polished finish), and the safety factor of each node is calculated for each specification classification. Then, a safety factor distribution diagram (contour diagram) is created based on the calculated safety factor of each node. The evaluator can use the created safety factor distribution diagram to evaluate the safety factor of each part of the bogie frame.

In the method of Patent Document 1, for example, a safety factor distribution diagram is created for each specification category. In this case, the evaluator of the bogie frame must understand which specification category the evaluation target part should be based on, and then select from multiple safety factor distribution diagrams a safety factor distribution diagram that corresponds to the specification category of the evaluation target part to evaluate the strength. For this reason, if the evaluator does not understand which specification category the evaluation target part should be based on, the strength of the bogie frame cannot be appropriately evaluated. In addition, it is necessary to select a safety factor distribution diagram for each evaluation target part, and the strength of the bogie frame cannot be evaluated efficiently.

Patent Document 1 also describes another method of creating a safety factor distribution diagram, in which a single type of safety factor distribution diagram (contour diagram) is created by defining a durability limit diagram for determining the safety factor for each part. In this case, it is believed that the evaluator can efficiently evaluate the strength of each part of the bogie frame based on a single safety factor distribution diagram.

However, when design changes are made to the bogie frame (such as material changes or changes to the specifications of each part), the evaluator must redefine an appropriate endurance limit diagram for each part in accordance with the design changes. In this regard, if the evaluator has a lot of experience, he or she may be able to properly define the endurance limit diagram, but if the evaluator does not have enough experience, there is a risk that he or she will not be able to properly determine what kind of endurance limit diagram should be defined for the conditions of the design change. In this case, the strength of the bogie frame cannot be properly evaluated.

The present invention aims to provide an evaluation device, evaluation method, and program that enable appropriate and efficient strength evaluation of structural members.

The present invention relates to the following evaluation device, evaluation method, and program.

(1) an assignment unit that assigns one material class selected from a plurality of material classes to each of a plurality of nodes on a surface of an FEM model of a structural member to be evaluated, and assigns one specification class selected from a plurality of specification classes to each of the nodes;
a stress calculation unit that applies a load to the FEM model and calculates a stress generated on a surface of the FEM model;
a safety factor calculation unit that calculates a safety factor corresponding to the one material class and the one specification class assigned by the assignment unit for each of the plurality of nodes based on a plurality of pieces of safety factor information linked to the material class and the specification class and the stress calculated by the stress calculation unit;
A structural member evaluation device comprising:

(2) The structural member evaluation device described in (1) above further includes a distribution map creation unit that creates a safety factor distribution map of the structural member based on the safety factor corresponding to the one material class and the one specification class calculated by the safety factor calculation unit for each of the multiple nodes.

(3) The safety factor calculation unit
A first processing unit that calculates a safety factor for each of the safety factor information for each of the plurality of nodes of the FEM model;
The structural member evaluation device described in (1) or (2) above, further comprising: a second processing unit that extracts, for each of the plurality of nodes, a safety factor calculated based on the safety factor information corresponding to the one material class and the one specification class assigned by the assignment unit, from the safety factors calculated by the first processing unit for each of the safety factor information.

(4) The safety factor calculation unit
a first processing unit that extracts, for each of the plurality of nodes of the FEM model, the safety factor information corresponding to the one material class and the one specification class assigned by the assignment unit from the plurality of pieces of safety factor information;
The structural member evaluation device described in (1) or (2) above, further comprising: a second processing unit that calculates a safety factor for each of the plurality of nodes based on the safety factor information extracted by the first processing unit.

(5) The structural member evaluation device according to any one of (1) to (4) above, further comprising an extraction unit that compares the safety factor calculated by the safety factor calculation unit with the safety factor conditions set for each of the plurality of nodes, and extracts the nodes that do not satisfy the conditions.

(6) The structural member evaluation device described in (5) above, wherein the extraction unit further generates notification data for notifying a portion of the structural member that corresponds to the extracted node or a specified area that includes the portion.

(7) The structural member evaluation device described in (6) above, in which the notification data is data that notifies the part of the structural member that corresponds to the extracted node or the specified area including that part as a focus inspection part.

(8) The structural member evaluation device described in (7) above, in which the notification data is data showing the focus inspection area on a diagram of the structural member.

(9) The structural member evaluation device described in (7) above, in which the notification data is data indicating the inspection target part that is to be the focus inspection part from among a plurality of inspection target parts previously set for the structural member.

(10) The structural member evaluation device described in (2) above further includes an extraction unit that compares the safety factor calculated by the safety factor calculation unit with the safety factor conditions set for each of the multiple nodes, extracts the nodes that do not satisfy the conditions, and generates data to display, as a focus inspection unit, the parts of the structural member that correspond to the extracted nodes or a specified area including the parts, on the safety factor distribution map created by the distribution map creation unit.

(11) The structural member evaluation device according to any one of (1) to (10) above, wherein the structural member is a bogie frame for a railway vehicle.

(12) A computer-implemented evaluation method, comprising:
an assignment step of assigning one material class selected from a plurality of material classes to each of a plurality of nodes on a surface of an FEM model of a structural member to be evaluated, and assigning one specification class selected from a plurality of specification classes to each of the nodes;
a stress calculation step of applying a load to the FEM model and calculating a stress generated on a surface of the FEM model;
a safety factor calculation step of calculating a safety factor corresponding to the one material class and the one specification class assigned in the assignment step for each of the plurality of nodes based on a plurality of pieces of safety factor information associated with the material class and the specification class and the stress calculated in the stress calculation step;
A method for evaluating a structural member comprising:

(13) The method for evaluating a structural member described in (12) above, further comprising a distribution map creation step of creating a safety factor distribution map of the structural member based on the safety factor corresponding to the one material class and the one specification class calculated for each of the plurality of nodes in the safety factor calculation step.

(14) The safety factor calculation step includes:
A first step of calculating a safety factor for each of the safety factor information for each of the plurality of nodes of the FEM model;
A method for evaluating a structural member as described in (12) or (13) above, comprising: a second step of extracting, for each of the plurality of nodes, a safety factor calculated based on the safety factor information corresponding to the one material class and the one specification class assigned in the assignment step, from the safety factors calculated for each of the safety factor information in the first step.

(15) The safety factor calculation step includes:
a first step of extracting, for each of the plurality of nodes of the FEM model, the safety factor information corresponding to the one material class and the one specification class assigned in the assigning step from the plurality of pieces of safety factor information;
A method for evaluating a structural member according to (12) or (13) above, comprising a second step of calculating a safety factor for each of the plurality of nodes based on the safety factor information extracted in the first step.

(16) The method for evaluating a structural member according to any one of (12) to (15) above, further comprising an extraction step of comparing the safety factor calculated in the safety factor calculation step with the safety factor conditions set for each of the plurality of nodes, and extracting the nodes that do not satisfy the conditions.

(17) The method for evaluating a structural member described in (16) above, further comprising generating notification data in the extraction step for notifying a portion of the structural member that corresponds to the extracted node or a specified area that includes the portion.

(18) The method for evaluating a structural member described in (17) above, in which the notification data is data that notifies a portion of the structural member that corresponds to the extracted node or the specified area including that portion as a focus inspection portion.

(19) The method for evaluating a structural member described in (18) above, in which the notification data is data showing the focus inspection area on a diagram of the structural member.

(20) The method for evaluating a structural member described in (18) above, in which the notification data is data indicating the inspection target part that is to be the focus inspection part from among a plurality of inspection target parts previously set for the structural member.

(21) The method for evaluating a structural member described in (13) above further comprises a step of comparing the safety factor calculated in the safety factor calculation step with the safety factor conditions set for each of the plurality of nodes, extracting the nodes that do not satisfy the conditions, and generating data for showing the parts of the structural member corresponding to the extracted nodes or a specified area including the parts as a focus inspection area on the safety factor distribution map created in the distribution map creation step.

(22) A method for evaluating a structural member according to any one of (12) to (21) above, wherein the structural member is a bogie frame for a railway vehicle.

(23) A program for causing a computer to execute the evaluation method described in any one of (12) to (22) above.

The present invention allows for appropriate and efficient strength evaluation of structural members, regardless of the experience of the evaluator.

FIG. 1 is a block diagram showing a schematic configuration of an evaluation device according to an embodiment of the present invention. FIG. 2 is a perspective view showing an example of a railcar bogie chassis to be evaluated by the evaluation device according to this embodiment. FIG. 3 is a block diagram specifically showing the configuration of an evaluation device according to an embodiment of the present invention. FIG. 4 is a diagram for explaining a method for extracting a reference node pair by the stress calculation unit. FIG. 5 is a diagram for explaining a method for defining a virtual node by the stress calculation unit. FIG. 6 is a stress limit diagram. FIG. 7 is a flow diagram showing the operation of the evaluation device according to one embodiment of the present invention. FIG. 8 is a block diagram showing an example of a computer that realizes an evaluation device according to an embodiment of the present invention.

The following describes an evaluation device, evaluation method, and program for a structural member according to an embodiment of the present invention. In the following, a railroad vehicle bogie frame is used as an example of a structural member, and a case is described in which the strength values (safety factors) of each part of the railroad vehicle bogie frame are calculated using an evaluation device.

[Device configuration]
1 is a block diagram showing a schematic configuration of an evaluation device according to an embodiment of the present invention. As shown in FIG. 1, an evaluation device 10 according to the present embodiment includes a stress applying unit 12, a stress calculating unit 14, and a safety factor calculating unit 16.

Figure 2 is a perspective view showing an example of a bogie frame for a railway vehicle to be evaluated by the evaluation device 10 according to this embodiment. As shown in Figure 2, the bogie frame 100 has a pair of side beams 102 and a cross beam 104 connecting the pair of side beams 102. The cross beam 104 has a pair of pipe members 104a. In the following, a case will be described in which the evaluation device 10 calculates the safety factor of each part of the bogie frame 100 using an FEM model of the bogie frame 100. However, the configuration of the bogie frame whose strength is evaluated by the evaluation device 10 is not limited to the bogie frame 100 shown in Figure 2, and the evaluation device 10 is used to perform strength evaluation of bogie frames of various configurations.

As shown in FIG. 1, the assigning unit 12 of the evaluation device 10 is provided with a FEM (Finite Element Method) model of the structural member to be evaluated (in this embodiment, the bogie frame 100). The FEM model has multiple elements and multiple nodes. In this embodiment, the multiple nodes may include corner nodes (primary nodes: nodes located at the corners of the elements) as well as intermediate nodes (secondary nodes: nodes located on the element sides so as to be located between the corner nodes). Note that a known analytical model used in stress analysis by the finite element method (FEM) can be used as the FEM model, so a detailed description of the FEM model will be omitted.

In this embodiment, the FEM model created in another device is provided to the assigning unit 12, but the assigning unit 12 may also create the FEM model based on user operations, as in known FEM analysis software.

The assigning unit 12 assigns one material class selected from among multiple material classes to each of multiple nodes on the surface of the FEM model, and also assigns one specification class selected from among multiple specification classes. In this embodiment, the material class is a class indicating the type of material (e.g., SM400, SM400A, SM490, SM490A, etc.) of the part corresponding to each node in the bogie frame 100. In addition, the specification class is a class indicating the state (e.g., base material, as welded, polished finish, etc.) of the part corresponding to each node. In this embodiment, the assigning unit 12 assigns a material class and a specification class to each node according to the material class and specification class input by the user.

The stress calculation unit 14 applies a load to the FEM model and calculates the stress generated on the surface of the FEM model. In this embodiment, the stress calculation unit 14 applies a load to the FEM model based on a load set by the user, and calculates the stress generated on the surface of the FEM model by performing stress analysis using the finite element method.

The safety factor calculation unit 16 uses multiple pieces of safety factor information to calculate the safety factor of each node on the surface of the FEM model. In this embodiment, the safety factor information is information for calculating the safety factor at a node based on the stress generated around the node. The multiple pieces of safety factor information may be input by a user when the evaluation device 10 evaluates the bogie frame 100, or may be stored in advance in the evaluation device 10. The safety factor information will be described later.

Each of the multiple safety factor information is linked to a specific material category and specification category. For example, one piece of safety factor information is linked to the material category "SM400" and the specification category "base material." Furthermore, for example, another piece of safety factor information is linked to the material category "SM400" and the specification category "as welded." In this embodiment, the number of safety factor information used is the number obtained by multiplying the number of material categories that can be assigned to each node by the number of specification categories that can be assigned to each node.

In this embodiment, the safety factor calculation unit 16 calculates a safety factor corresponding to the material classification and specification classification assigned by the assignment unit 12 for each of the multiple nodes on the surface of the FEM model based on multiple pieces of safety factor information and the stress calculated by the stress calculation unit 14.

As described above, in the evaluation device 10 according to this embodiment, the assigning unit 12 assigns one material class selected from among multiple material classes to each node of the FEM model, and also assigns one specification class selected from among multiple specification classes. The safety factor calculation unit 16 calculates the safety factor of each node based on the stress calculated by the stress calculation unit 14 and multiple pieces of safety factor information.

Here, each of the multiple pieces of safety factor information is linked to a specific material classification and specification classification. Therefore, the safety factor calculation unit 16 can determine the safety factor information to be used when calculating the safety factor of each node from the multiple pieces of safety factor information by comparing the material classification and specification classification assigned by the assignment unit 12 with the material classification and specification classification associated with each piece of safety factor information. This allows the safety factor calculation unit 16 to calculate the safety factor corresponding to the material classification and specification classification assigned by the assignment unit 12 for each node.

In this way, the evaluation device 10 according to this embodiment can set the material class and specification class of each node, and thereby calculate a safety factor according to the set material class and specification class. In this case, the strength evaluation of the bogie frame 100 can be performed more efficiently than when multiple safety factors are calculated for each node and the evaluator selects a safety factor corresponding to the specification class and material class from the multiple safety factors.

Furthermore, according to the evaluation device 10 of this embodiment, even if design changes (material changes, specification changes for each part) are made to the bogie frame, the safety factor can be calculated according to the changed material class and specification class by updating the material class and specification class assigned to each node of the FEM model. In this case, since the evaluator does not need to redefine appropriate safety factor information according to the changed material class and specification class, even if the evaluator does not have much experience, the safety factor can be calculated for each node based on appropriate safety factor information.

As a result of the above, the evaluation device 10 according to this embodiment can appropriately and efficiently perform strength evaluation of the bogie frame 100, regardless of the experience of the evaluator.

Next, the specific configuration of the evaluation device 10 will be described. Figure 3 is a block diagram specifically showing the configuration of an evaluation device according to one embodiment of the present invention.

As shown in FIG. 3, the evaluation device 10 according to this embodiment includes a distribution map creation unit 18, an extraction unit 20, and a safety factor information storage unit 22 (hereinafter abbreviated as storage unit 22) in addition to an application unit 12, a stress calculation unit 14, and a safety factor calculation unit 16. The storage unit 22 stores multiple pieces of safety factor information linked to material classifications and specification classifications.

In the evaluation device 10 according to this embodiment, as in the above-described embodiment, the assignment unit 12 assigns a material classification and a specification classification to each node on the surface of the FEM model, and the stress calculation unit 14 applies a load to the FEM model to calculate the stress generated on the surface of the FEM model. The method of calculating the stress generated on the surface of the FEM model will be described later.

In this embodiment, the safety factor calculation unit 16 includes a first processing unit 16a and a second processing unit 16b. The first processing unit 16a calculates a safety factor for each of the multiple nodes on the surface of the FEM model, for each piece of safety factor information stored in the storage unit 22. In this embodiment, the first processing unit 16a stores the safety factor of each node calculated for each piece of safety factor information in the storage unit 22. The method of calculating the safety factor will be described later.

The second processing unit 16b extracts, for each of the multiple nodes on the surface of the FEM model, a safety factor calculated based on the safety factor information corresponding to the material classification and specification classification assigned by the assignment unit 12 from the safety factors calculated by the first processing unit 16a for each piece of safety factor information. The second processing unit 16b outputs the extracted safety factor to the distribution map creation unit 18 and the extraction unit 20.

The distribution map creation unit 18 creates a safety factor distribution map showing the safety factors of the parts of the bogie frame 100 corresponding to each node, based on the safety factor of each node provided by the second processing unit 16b. In this embodiment, the distribution map creation unit 18 creates, for example, a safety factor distribution map (contour diagram) in which the safety factor of each part of the bogie frame 100 is displayed as a contour based on its magnitude. The distribution map creation unit 18 displays the created safety factor distribution map on a display device (not shown). The distribution map creation unit 18 also stores the created safety factor distribution map in the memory unit 22.

The extraction unit 20 compares the safety factor of each node provided by the second processing unit 16b with the safety factor condition (threshold value) set for each node, and extracts nodes that do not satisfy the condition. In this embodiment, the safety factor condition for each node is pre-stored in the storage unit 22.

The extraction unit 20 also generates notification data for notifying the user (evaluator) of the part in the bogie frame 100 that corresponds to the extracted node or a predetermined area including the part. In this embodiment, the extraction unit 20 generates notification data for notifying, for example, the part in the bogie frame 100 that corresponds to the node that does not satisfy the above condition or a predetermined area including the part, as a key inspection part. The notification data may be, for example, data showing the key inspection part on a diagram of the bogie frame 100 on the display device, or data clearly indicating an inspection target part that will be the key inspection part from among a plurality of inspection target parts (a plurality of inspection target parts previously set for the bogie frame 100) listed on the display device. The notification data may also be data for showing the key inspection part on a safety factor distribution diagram created by the distribution diagram creation unit 18.

In the evaluation device 10 according to this embodiment, too, by setting the material class and specification class of each node, it is possible to calculate a safety factor according to the set material class and specification class. Furthermore, in the evaluation device 10 according to this embodiment, when a design change is made to the bogie frame (material change, specification change of each part), it is possible to calculate a safety factor according to the changed material class and specification class by updating the material class and specification class assigned to each node of the FEM model. As a result, the evaluation device 10 according to this embodiment can appropriately and efficiently perform a strength evaluation of the bogie frame 100 regardless of the experience of the evaluator.

In addition, in this embodiment, the first processing unit 16a calculates a safety factor for each safety factor information stored in the memory unit 22. Then, the second processing unit 16b extracts a safety factor calculated based on the safety factor information corresponding to the material classification and specification classification assigned by the assignment unit 12 from the safety factors calculated by the first processing unit 16a for each safety factor information. That is, in this embodiment, the first processing unit 16a calculates multiple safety factors for each node based on multiple safety factor information, and the second processing unit 16b extracts an appropriate safety factor from the calculated multiple safety factors. Therefore, by retaining the data of the safety factor calculated by the first processing unit 16a, even if the specification classification of an arbitrary node is changed (for example, from as-welded to polished), the second processing unit 16b can extract an appropriate safety factor from the above-mentioned retained safety factor data without performing the processing by the first processing unit 16a again. As a result, even if the specification classification of an arbitrary node is changed, the strength evaluation of the bogie frame 100 can be performed quickly.

In addition, in this embodiment, a safety factor distribution diagram of the bogie frame 100 is created by the distribution diagram creation unit 18. In this safety factor distribution diagram, a safety factor calculated based on appropriate safety factor information for each node is shown. Therefore, the evaluator of the bogie frame 100 can evaluate the strength of the bogie frame 100 using a single safety factor distribution diagram created by the distribution diagram creation unit 18. In other words, the evaluator does not need to compare multiple safety factor distribution diagrams when evaluating the strength of the bogie frame 100. This makes it possible to more efficiently evaluate the strength of the bogie frame 100.

In addition, in this embodiment, the extraction unit 20 extracts nodes that do not satisfy a predetermined condition, and generates notification data to notify the part corresponding to the node or a predetermined area including the part. By using this notification data, the evaluator can easily identify the parts of the bogie frame 100 that should be inspected with priority.

(Calculation method of stress and safety factor)
An example of a method for calculating the stress occurring on the surface of the FEM model and the safety factor of each node will be described below, but the method for calculating the stress and the safety factor is not limited to the following example, and the stress and the safety factor can be calculated using various known methods. For example, the stress and the safety factor may be calculated by the method disclosed in the above-mentioned Patent Document 1.

(Stress calculation method)
First, a method of calculating stress will be described. In this embodiment, the stress calculation unit 14 extracts a plurality of reference node pairs from a plurality of nodes that belong to a common element on the surface of the FEM model and the target node, with an arbitrary node on the surface of the FEM model as a target node. Specifically, the stress calculation unit 14 extracts a plurality of combinations of two nodes that can form a triangle together with the target node as reference node pairs. The target node is a node that is the target of calculation of the safety factor. In this embodiment, the stress calculation unit 14 may select, for example, a plurality of nodes that belong to an area specified by a user as the target nodes, or may select all nodes on the surface of the FEM model as the target nodes. In addition, the stress calculation unit 14 may select only corner nodes as the target nodes. Hereinafter, a method of extracting reference node pairs will be described with reference to the drawings.

Figure 4 is a diagram for explaining a method for extracting reference node pairs by the stress calculation unit 14. Note that FIG. 4 shows elements e1, e2, e3, and e4, which are some of the multiple elements on the surface of the FEM model. Also shown in FIG. 4 as multiple nodes are corner nodes A, B, C, D, E, and F, and intermediate nodes G, H, I, J, K, L, M, N, and O. Note that in FIG. 4, it is assumed that there is no element edge connecting corner node B and corner node F. In other words, there is a space between element e1 and element e4 where no elements exist.

For example, in FIG. 4, corner node A belonging to elements e1 to e4 is taken as the target node. In this case, the stress calculation unit 14 extracts a reference node pair from multiple nodes B to O (excluding target node A) that belong to elements e1 to e4 that are common to target node A. Specifically, the stress calculation unit 14 extracts a combination of two nodes that can form a triangle together with target node A as the reference node pair.

For example, of elements B to O shown in FIG. 4, nodes B and C belong to element e1, which is common to target node A, and can form a triangle with target node A. Therefore, the stress calculation unit 14 extracts the combination of nodes B and C as a reference node pair. Also, for example, nodes B and H also belong to element e1, which is common to target node A, and can form a triangle with target node A. Therefore, the stress calculation unit 14 also extracts the combination of nodes B and H as a reference node pair.

However, the stress calculation unit 14 excludes from the reference node pair a combination of two nodes that can form a triangle together with the target node, but does not have a common element to which both nodes belong. For example, among elements B to O shown in FIG. 4, nodes H and K belong to elements e1, e2, and e3 that are common to the target node A, and can form a triangle together with the target node A. However, there is no common element to which nodes H and K belong. Specifically, node H belongs to element e1, and node K belongs to elements e2 and e3. Therefore, the combination of nodes H and K is a combination in which there is no common element to which both nodes belong, and the stress calculation unit 14 does not extract the combination of nodes H and K as a reference node pair. Similarly, for example, nodes H and O belong to elements e1 and e4 that are common to the target node A, and can form a triangle together with the target node A. However, there is no common element to which nodes H and O belong. Specifically, node H belongs to element e1, and node O belongs to element e4. Therefore, the combination of nodes H and O is also a combination in which there is no common element to which both nodes belong, and the stress calculation unit 14 does not extract the combination of nodes H and O as a reference node pair.

In this embodiment, the stress calculation unit 14 extracts one or more reference node pairs for each target node in accordance with the above rules. For example, when node A is set as the target node, the stress calculation unit 14 extracts 32 combinations of nodes, namely nodes B, C, node B, H, node B, I, node C, G, node C, H, node G, H, node G, I, node H, I, node C, D, node C, J, node C, K, node D, I, node D, J, node I, J, node I, K, node J, K, node D, E, node D, L, node D, M, node E, K, node E, L, node K, L, node K, M, node L, M, node E, F, node E, N, node E, O, node F, M, node F, N, node M, N, node M, O, and node N, O, as reference node pairs.

In this embodiment, the intermediate node can also be the target node. In this case, the stress calculation unit 14 extracts the reference node pairs according to the above-mentioned rules. For example, when the intermediate node I is set as the target node, the stress calculation unit 14 extracts multiple reference node pairs from the target node I and multiple nodes A to D, G, H, J, and K that belong to the elements e1 and e2 surrounding the target node I. Specifically, the stress calculation unit 14 extracts 18 combinations of nodes, namely nodes A, B, nodes A, D, nodes A, G, nodes A, H, nodes A, J, nodes A, K, nodes B, C, nodes B, G, nodes B, H, nodes C, D, nodes C, G, nodes C, H, nodes C, J, nodes C, K, nodes D, J, nodes D, K, nodes G, H, and nodes J, K, as the reference node pairs.

Although detailed explanation is omitted, for example, in order to reduce the burden on the evaluation device 10, some of the above-mentioned reference node pairs may be excluded from the reference node pairs. For example, a combination of an intermediate node located on the same element side as the target node and an intermediate node located on a different element side from the target node may be excluded from the reference node pair. Therefore, if node A is the target node in Figure 4, a combination of intermediate node G (or intermediate node I) located on the same element side as the target node A and intermediate node H located on a different element side from the target node A may be excluded from the reference node pair. Note that the combination of nodes to be excluded from the reference node pair can be set appropriately by the user.

The stress calculation unit 14 defines a virtual node for each reference node pair extracted as described above. Specifically, the stress calculation unit 14 defines one of the two nodes constituting the reference node pair as a first reference node and the other as a second reference node, and defines a virtual node between the first reference node and the second reference node.

Figure 5 is a diagram for explaining the method of defining a virtual node by the stress calculation unit 14. Note that element e1 shown in Figure 4 is shown in Figure 5. In the following, a case where a virtual node is defined for the reference node pair G, I with node A as the target node will be described.

5, when defining a virtual node for a reference node pair G and I, the stress calculation unit 14 defines, for example, node G as a first reference node, node I as a second reference node, and defines a virtual node V on a line segment GI connecting the first reference node G and the second reference node I. In this embodiment, the stress calculation unit 14 changes the position of the virtual node by changing the ratio of the distance _D1 between the first reference node G and the virtual node V to the distance _D0 between the first reference node G and the second reference node I in the range of 0 to 1. This allows the stress calculation unit 14 to define a plurality of virtual nodes for each of a plurality of reference node pairs.

In this specification, when the ratio of the distance between the first reference node and the virtual node to the distance between the first reference node and the second reference node is 0, it means that the first reference node is defined as a virtual node, and when the ratio of the distance between the first reference node and the virtual node to the distance between the first reference node and the second reference node is 1, it means that the second reference node is defined as a virtual node.

The ratio of the distance between the first reference node and the virtual node to the distance between the first reference node and the second reference node may be changed continuously in the range of 0 to 1, or multiple values may be set by the user as appropriate. Also, for example, the number of virtual nodes defined for one reference node pair may be set in advance. In this case, a preset number of virtual nodes may be defined at equal intervals between the first reference node and the second reference node.

In this embodiment, the stress calculation unit 14 defines virtual nodes for each of the multiple nodes on the surface of the FEM model according to the above rules. That is, for each node, multiple virtual nodes are defined to surround the node.

Next, the stress calculation unit 14 applies a load to the FEM model. In this embodiment, the stress calculation unit 14 applies a load to the FEM model under a plurality of different load conditions. The load conditions can be classified into, for example, a load in the up-down direction, a load in the left-right direction, a load in the front-rear direction, and a load in the torsional direction. In this embodiment, a load can be applied to the FEM model according to the load conditions shown in, for example, JIS E 4207:2019.

In this embodiment, the average load and the fluctuating load are set in advance for each load condition. In addition, in this embodiment, the stress calculation unit 14 applies to the FEM model a load obtained by adding the average load and the fluctuating load for each load condition.

Next, the stress calculation unit 14 obtains the displacement of each node (corner node, intermediate node, and virtual node) before and after applying the load for each of the multiple load conditions. In this embodiment, the stress calculation unit 14 obtains the displacement of the corner node and intermediate node by using a function similar to that of known FEM analysis software. Meanwhile, the displacement of the virtual node can be calculated by interpolation (direct interpolation) based on the displacement of the first reference node and the second reference node. For example, referring to FIG. 5, the stress calculation unit 14 calculates the displacement of the virtual node V based on the displacement of the first reference node G and the displacement of the second reference node I.

In this embodiment, the stress calculation unit 14 calculates, for example, the displacement of the virtual node V as a displacement vector. Specifically, when the displacement of the first reference node G is ΔG (=( _Δx1 , _Δy1 , _Δz1 )) and the displacement of the second reference node I is ΔI (=( _Δx2 , _Δy2 , _Δz2 )), the displacement ΔV of the virtual node V is calculated by the following formula (1).
ΔV=(1−(D ₁ /D ₀ ))×ΔG+(D ₁ /D ₀ )×ΔI (1)

Next, the stress calculation unit 14 calculates the strain occurring between the target node A and the virtual node V based on the displacement of the target node A and the displacement of the virtual node V. In this embodiment, the stress calculation unit 14 calculates the strain λ, for example, by the following formula (2).
λ=(AV ₁ −AV ₀ )/AV ₀ (2)
In the above formula, AV ₀ indicates the distance between the target node A and the virtual node V before the load is applied by the stress calculation unit 14, and AV ₁ indicates the distance between the target node A and the virtual node V after the load is applied by the stress calculation unit 14.

In this embodiment, the stress calculation unit 14 calculates the strain occurring between the target node and the virtual node for each position of the virtual node. That is, for each node, the strain occurring around that node is calculated. Next, the stress calculation unit 14 calculates the stress occurring between the target node and the virtual node for each position of the virtual node based on the strain calculated as described above and the Young's modulus that is preset in the FEM model. That is, the stress occurring around that node is calculated for each node.

In this embodiment, as described above, loads are applied to the FEM model under multiple load conditions, and the stress calculation unit 14 calculates the stress occurring between the target node and the virtual node for each load condition. In other words, the stress occurring around each node is calculated for each load condition.

Next, the stress calculation unit 14 calculates the average stress component and the variable stress component of the stress occurring between the target node and the virtual node calculated for each load condition. As described above, in this embodiment, the stress calculation unit 14 applies a load obtained by adding the average load and the variable load to the FEM model. In other words, the stress occurring between the target node and the virtual node calculated by the stress calculation unit 14 is a stress calculated based on the load obtained by adding the average load and the variable load.

Therefore, in this embodiment, the stress calculation unit 14 can calculate the average stress component of the stress occurring between the target node and the virtual node for each load condition by multiplying the stress calculated for each load condition by the ratio of the average load to the load applied to the FEM model. In addition, the stress calculation unit 14 can calculate the variable stress component of the stress occurring between the target node and the virtual node for each load condition by multiplying the stress calculated for each load condition by the ratio of the variable load to the load applied to the FEM model.

For example, assume that the load applied to the FEM model is 130 kN, of which the average load is 100 kN and the fluctuating load is 30 kN. Under these conditions, assume that the stress calculated by the stress calculation unit 14 between the target node and the virtual node is 130 MPa. In this case, the stress calculated by the stress calculation unit 14 is multiplied by the ratio (100/130) of the average load (100 kN) to the load (130 kN) applied by the stress calculation unit 14 to the FEM model, and the average stress component of the stress generated between the target node and the virtual node is calculated to be 100 MPa. In addition, the stress calculated by the stress calculation unit 14 is multiplied by the ratio (30/130) of the fluctuating load (30 kN) to the load (130 kN) applied by the stress calculation unit 14 to the FEM model, and the fluctuating stress component of the stress generated between the target node and the virtual node is calculated to be 30 MPa.

The stress calculation unit 14 calculates the composite average stress between the target node and the virtual node by taking the sum of the average stress components calculated for each load condition as described above. The stress calculation unit 14 also calculates the composite variable stress between the target node and the virtual node by taking the square root of the sum of the squares of the variable stress components calculated for each load condition as described above. In this embodiment, the stress calculation unit 14 calculates the composite average stress and composite variable stress that occur between the virtual node and the target node for each virtual node as described above. Therefore, in this embodiment, multiple composite average stresses and multiple composite variable stresses are calculated for one node (target node).

(Safety factor calculation method)
Next, a method for calculating the safety factor will be described. In this embodiment, the first processing unit 16a calculates the safety factor of each node by using the composite mean stress and composite variable stress calculated by the stress calculation unit 14 as described above and a plurality of pieces of safety factor information stored in the storage unit 22. In this embodiment, information indicating the relationship between the composite mean stress, composite variable stress, and stress limit (hereinafter referred to as stress limit relationship) is used as the safety factor information.

Figure 6 is a diagram (stress limit diagram) showing an example of a stress limit relationship. In the stress limit relationship shown in Figure 6, a stress limit line is defined on a graph with the mean stress on the first axis (horizontal axis) and the fluctuating stress on the second axis (vertical axis).

As shown in FIG. 6, in this embodiment, the first processing unit 16a first plots points indicating the composite mean stress and composite variable stress calculated for an arbitrary node on a graph showing stress limit lines. Note that FIG. 6 shows the case where the composite mean stress is "-50 MPa" and the composite variable stress is "50 MPa."

Next, first processing unit 16a calculates a straight line (hereinafter, referred to as a judgment line) that passes through the plotted points and the origin. Next, first processing unit 16a calculates a safety factor SF based on the following formula (3).
SF=OP1/OP2 (3)
In the above formula (3), OP1 is the length of the line segment connecting the intersection of the judgment line and the stress limit line and the origin, and OP2 is the length of the line segment connecting the point plotted by the safety factor calculation unit 16 on the judgment line and the origin.

For example, the stress limit diagram shown in JIS E 4207:2019 can be used to determine the stress limit relationship.

As described above, in this embodiment, multiple virtual nodes are defined around one node (target node), and multiple composite mean stresses and multiple composite variable stresses are calculated for the one node. The first processing unit 16a calculates the safety factor for each node using the composite mean stress and composite variable stress calculated for each virtual node. Therefore, in this embodiment, multiple safety factors are calculated for each node from one stress limit relationship (stress limit diagram).

Next, the first processing unit 16a extracts the lowest safety factor (hereinafter referred to as the minimum safety factor) from among the multiple safety factors calculated for each node based on one stress limit relationship (stress limit diagram). In this embodiment, the first processing unit 16a calculates the minimum safety factor for each of the multiple stress limit relationships. Therefore, in this embodiment, the first processing unit 16a calculates multiple minimum safety factors for each node.

In this embodiment, the second processing unit 16b extracts, for each of the multiple nodes on the surface of the FEM model, a minimum safety factor calculated based on the safety factor information corresponding to the material class and specification class assigned by the assignment unit 12 from the minimum safety factors calculated by the first processing unit 16a for each safety factor information. The second processing unit 16b outputs the extracted safety factor to the distribution map creation unit 18 and the extraction unit 20 as the safety factor of each node. In this embodiment, the safety factor of each node on the surface of the FEM model is calculated in the above manner.

(Modification)
In the above embodiment, the first processing unit 16a calculates the safety factor for each of the multiple nodes for each safety factor information, and the second processing unit 16b extracts the safety factor calculated based on the safety factor information corresponding to the material class and specification class assigned by the assigning unit 12 from the safety factor calculated for each safety factor information. However, the first processing unit 16a may extract the safety factor information corresponding to the material class and specification class assigned by the assigning unit 12 from the multiple safety factor information for each of the multiple nodes, and the second processing unit 16b may calculate the safety factor for each of the multiple nodes based on the safety factor information extracted by the first processing unit 16a. In this case, since the first processing unit 16a extracts appropriate safety factor information in advance for each node, the burden on the evaluation device 10 can be reduced compared to the case where the safety factor is calculated based on multiple safety factor information for each node. In this case, the second processing unit 16b may calculate the safety factor by a method similar to the above-mentioned method, or may calculate the safety factor using other known methods (for example, the method described in the above-mentioned Patent Document 1).

[Device Operation]
Next, the operation of the evaluation device 10 according to the present embodiment will be described with reference to Fig. 7. Fig. 7 is a flow diagram showing the operation of the evaluation device 10 according to an embodiment of the present invention. Note that the evaluation method according to the present embodiment is carried out by operating the evaluation device 10.

As shown in FIG. 7, in this embodiment, as described above, first, the assigning unit 12 assigns a material class and a specification class to each of a plurality of nodes on the surface of the FEM model of the bogie frame 100 (step S1). Next, as described above, the stress calculation unit 14 applies a load to the FEM model and calculates the stress generated on the surface of the FEM model (step S2).

Next, as described above, the safety factor calculation unit 16 calculates the safety factor corresponding to the material classification and specification classification assigned by the assignment unit 12 for each of the multiple nodes (step S3). In step S3, for example, the first processing unit 16a first calculates the safety factor for each safety factor information for each node (first step A1), and then the second processing unit 16b may extract the safety factor calculated based on the safety factor information corresponding to the material classification and specification classification assigned by the assignment unit 12 from the safety factors calculated for each safety factor information for each node (second step A2). In addition, in step S3, for example, the first processing unit 16a first extracts the safety factor information corresponding to the material classification and specification classification assigned by the assignment unit 12 from the multiple safety factor information for each node (first step B1), and then the second processing unit 16b may calculate the safety factor for each node based on the safety factor information extracted by the first processing unit 16a (second step B2).

Next, as described above, the distribution map creation unit 18 creates a safety factor distribution map (step S4). The extraction unit 20 also extracts nodes whose safety factors do not satisfy a predetermined condition (step S5). After that, the extraction unit 20 generates notification data for notifying the parts of the bogie frame 100 that correspond to the nodes that do not satisfy the above-mentioned condition or a predetermined area that includes the parts (step S6).

In FIG. 7, step S2 is executed after step S1, but step S1 may be executed after step S2. For example, step S1 may be executed between step S2 and step S3. Also, for example, step S1 may be executed between the first step A1 and the second step A2 of step S3. Also, in FIG. 7, steps S5 and S6 are executed after step S4, but step S4 may be executed after step S5. For example, step S4 may be executed between step S5 and step S6, or step S4 may be executed after step S6.

[program]
The program according to this embodiment may be a program that causes a computer to execute steps S1 to S6 shown in Fig. 7. By installing and executing this program in a computer, the evaluation device and evaluation method according to this embodiment can be realized. In this case, the processor of the computer functions as the applying unit 12, the stress calculating unit 14, the safety factor calculating unit 16 (the first processing unit 16a and the second processing unit 16b), and the extracting unit 20, and performs processing.

In addition, in this embodiment, the memory unit 22 is realized by storing the data files that make up these in a storage device such as a hard disk provided in the computer, or by mounting a recording medium on which these data files are stored in a reading device connected to the computer.

The program according to this embodiment may be executed by a computer system constructed by a plurality of computers. In this case, each computer may function as any one of the application unit 12, the stress calculation unit 14, the safety factor calculation unit 16 (first processing unit 16a and second processing unit 16b), the distribution map creation unit 18, and the extraction unit 20. The storage unit 22 may be constructed on a computer separate from the computer that executes the program according to this embodiment.

[Physical configuration]
8 is a block diagram showing an example of a computer that realizes the evaluation device according to an embodiment of the present invention. The computer 110 realizes the evaluation device 10 according to the embodiment by executing a program according to the embodiment.

As shown in FIG. 8, the computer 110 includes a CPU 111, a main memory 112, a storage device 113, an input interface 114, a display controller 115, a data reader/writer 116, and a communication interface 117. These components are connected to each other via a bus 121 so as to be able to communicate data with each other. Note that the computer 110 may include a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) in addition to or instead of the CPU 111.

The CPU 111 loads the program (code) in this embodiment stored in the storage device 113 into the main memory 112 and executes it in a predetermined order to perform various calculations. The main memory 112 is typically a volatile storage device such as a DRAM (Dynamic Random Access Memory). The program in this embodiment is provided in a state stored in a computer-readable recording medium 120. The program in this embodiment may be distributed over the Internet connected via the communication interface 117.

Specific examples of the storage device 113 include a hard disk drive and a semiconductor storage device such as a flash memory. The input interface 114 mediates data transmission between the CPU 111 and input devices 118 such as a keyboard and a mouse. The display controller 115 is connected to the display device 119 and controls the display on the display device 119.

The data reader/writer 116 mediates data transmission between the CPU 111 and the recording medium 120, reads programs from the recording medium 120, and writes the results of processing in the computer 110 to the recording medium 120. The communication interface 117 mediates data transmission between the CPU 111 and other computers.

Specific examples of the recording medium 120 include general-purpose semiconductor storage devices such as CF (Compact Flash (registered trademark)) and SD (Secure Digital), magnetic recording media such as flexible disks, and optical recording media such as CD-ROMs (Compact Disk Read Only Memory).

The evaluation device 10 according to this embodiment may be realized by using hardware corresponding to each part, rather than a computer on which a program is installed. Also, the evaluation device 10 may be realized in part by a program and the remaining part by hardware.

[Other embodiments]
In the above embodiment, the evaluation device calculates the safety factor of a bogie frame for a railway vehicle, but the structural member to be evaluated by the evaluation device according to the present invention is not limited to the bogie frame for a railway vehicle. For example, the evaluation device may calculate the safety factor of each part of various structural members such as other machine structural members (such as automobile bodies), architectural structural members, and civil engineering structural members.

The present invention allows for appropriate and efficient strength evaluation of structural members, regardless of the experience of the evaluator.

REFERENCE SIGNS LIST 10 Evaluation device 12 Application unit 14 Stress calculation unit 16 Safety factor calculation unit 16a First processing unit 16b Second processing unit 18 Distribution map creation unit 20 Extraction unit 22 Safety factor information storage unit 100 Bogie frame

Claims (23)

an assigning unit that assigns one material class selected from a plurality of material classes to each of a plurality of nodes on a surface of an FEM model of a structural member to be evaluated, and assigns one specification class selected from a plurality of specification classes;
a stress calculation unit that applies a load to the FEM model and calculates a stress generated on a surface of the FEM model;
a safety factor calculation unit that calculates a safety factor corresponding to the one material class and the one specification class assigned by the assignment unit for each of the plurality of nodes based on a plurality of pieces of safety factor information linked to the material class and the specification class and the stress calculated by the stress calculation unit;
A structural member evaluation device comprising: The structural member evaluation device according to claim 1, further comprising a distribution map creation unit that creates a safety factor distribution map of the structural member based on the safety factor corresponding to the one material class and the one specification class calculated by the safety factor calculation unit for each of the multiple nodes. The safety factor calculation unit is
A first processing unit that calculates a safety factor for each of the safety factor information for each of the plurality of nodes of the FEM model;
3. The structural member evaluation device according to claim 1, further comprising: a second processing unit that extracts, for each of the plurality of nodes, a safety factor calculated based on the safety factor information corresponding to the one material class and the one specification class assigned by the assignment unit, from the safety factors calculated by the first processing unit for each of the safety factor information. The safety factor calculation unit is
a first processing unit that extracts, for each of the plurality of nodes of the FEM model, the safety factor information corresponding to the one material class and the one specification class assigned by the assignment unit from the plurality of pieces of safety factor information;
3. The structural member evaluation device according to claim 1, further comprising: a second processing unit that calculates a safety factor for each of the plurality of nodes based on the safety factor information extracted by the first processing unit. The structural member evaluation device according to any one of claims 1 to 4, further comprising an extraction unit that compares the safety factor calculated by the safety factor calculation unit with the safety factor conditions set for each of the plurality of nodes, and extracts the nodes that do not satisfy the conditions. The structural member evaluation device according to claim 5, wherein the extraction unit further generates notification data for notifying a portion of the structural member that corresponds to the extracted node or a specified area that includes the portion. The structural member evaluation device according to claim 6, wherein the notification data is data for notifying a portion of the structural member corresponding to the extracted node or the specified area including the portion as a focus inspection portion. The structural member evaluation device according to claim 7, wherein the notification data is data showing the focus inspection area on a diagram of the structural member. The structural member evaluation device according to claim 7, wherein the notification data is data indicating the inspection target part that is to be the focus inspection part from among a plurality of inspection target parts preset for the structural member. The structural member evaluation device according to claim 2 further comprises an extraction unit that compares the safety factor calculated by the safety factor calculation unit with the safety factor conditions set for each of the multiple nodes, extracts the nodes that do not satisfy the conditions, and generates data to display the parts of the structural member that correspond to the extracted nodes or a specified area including the parts as a focus inspection unit on the safety factor distribution map created by the distribution map creation unit. The structural member evaluation device according to any one of claims 1 to 10, wherein the structural member is a bogie frame for a railway vehicle. 1. A computer-implemented evaluation method comprising:
an assignment step of assigning one material class selected from a plurality of material classes to each of a plurality of nodes on a surface of an FEM model of a structural member to be evaluated, and assigning one specification class selected from a plurality of specification classes to each of the nodes;
a stress calculation step of applying a load to the FEM model and calculating a stress generated on a surface of the FEM model;
a safety factor calculation step of calculating a safety factor corresponding to the one material class and the one specification class assigned in the assignment step for each of the plurality of nodes based on a plurality of pieces of safety factor information associated with the material class and the specification class and the stress calculated in the stress calculation step;
A method for evaluating a structural member comprising: The method for evaluating a structural member according to claim 12, further comprising a distribution diagram creation step of creating a safety factor distribution diagram of the structural member based on the safety factors corresponding to the one material category and the one specification category calculated for each of the plurality of nodes in the safety factor calculation step. The safety factor calculation step includes:
A first step of calculating a safety factor for each of the safety factor information for each of the plurality of nodes of the FEM model;
and a second step of extracting, for each of the plurality of nodes, a safety factor calculated based on the safety factor information corresponding to the one material class and the one specification class assigned in the assignment step, from the safety factors calculated for each of the safety factor information in the first step. The safety factor calculation step includes:
a first step of extracting, for each of the plurality of nodes of the FEM model, the safety factor information corresponding to the one material class and the one specification class assigned in the assigning step from the plurality of pieces of safety factor information;
14. The method for evaluating a structural member according to claim 12, further comprising: a second step of calculating a safety factor for each of the plurality of nodes based on the safety factor information extracted in the first step. The method for evaluating a structural member according to any one of claims 12 to 15, further comprising an extraction step of comparing the safety factor calculated in the safety factor calculation step with a safety factor condition set for each of the plurality of nodes, and extracting the nodes that do not satisfy the condition. The method for evaluating a structural member according to claim 16, further comprising generating notification data in the extraction step for notifying a portion of the structural member that corresponds to the extracted node or a predetermined area that includes the portion. The method for evaluating a structural member according to claim 17, wherein the notification data is data for notifying a portion of the structural member corresponding to the extracted node or the specified area including the portion as a focus inspection portion. The method for evaluating a structural member according to claim 18, wherein the notification data is data showing the focus inspection area on a diagram of the structural member. The method for evaluating a structural member according to claim 18, wherein the notification data is data indicating the inspection target part that is to be the focus inspection part from among a plurality of inspection target parts preset for the structural member. The method for evaluating a structural member according to claim 13 further comprises a step of comparing the safety factor calculated in the safety factor calculation step with a safety factor condition set for each of the plurality of nodes, extracting the nodes that do not satisfy the condition, and generating data for showing the parts of the structural member corresponding to the extracted nodes or a predetermined area including the parts as a focus inspection area on the safety factor distribution map created in the distribution map creation step. The method for evaluating a structural member according to any one of claims 12 to 21, wherein the structural member is a bogie frame for a railway vehicle. A program for causing a computer to execute the evaluation method according to any one of claims 12 to 22.

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