JP7328547B2 - Strength test method - Google Patents

Description

The present invention relates to a strength test method.

Conventionally, in order to evaluate the situation in which an impacting object collides with a structure, there has been an impact test method in which a test body that simulates the partial structure of the structure is impacted.

However, in the conventional crash test method, plastic deformation occurs at an early stage at a location different from the designated evaluation location where evaluation is desired in the partial structure. In some cases, the limits could not be properly evaluated.

WO2015/083376

SUMMARY OF THE INVENTION An object of the present invention is to provide a strength test method capable of appropriately evaluating the strength limit of a portion to be evaluated in a partial structure in view of the problems of the background art described above.

The gist of the present invention is as follows.

(1) A strength testing method according to an aspect of the present invention includes a partial structure model preparation step of preparing a partial structure model simulating a partial structure; a weak point identification step of identifying a weak point in the partial structure model; An evaluation point designation step of designating an evaluation point from other points other than the weak point in the partial structure model, an evaluation model preparation step of preparing an evaluation model simulating the evaluation point, and applying an excess load to the evaluation model. and an evaluation test step.
(2) In the above (1), in the weak point identification step, a specific load is applied to the partial structure to identify the weak point in the partial structure, and in the evaluation test step, the evaluation is performed with the specific load. Said excess load may be greater than the distributed load acting on the site.
(3) In (1) or (2) above, the partial structure model preparation step may include converting the partial structure into a finite element model.
(4) In any one of the above (1) to (3), the weak point identification step performs analysis for outputting a strain or stress distribution as an analysis output on the partial structure model, and outputs the analysis output. An area based on which the index is larger than a predetermined threshold may be identified as the weak point.
(5) In any one of (1) to (4) above, the evaluation point includes a first member, a second member, and an evaluation connection portion that connects the first member and the second member. It may be a structure having
(6) In (5) above, the evaluation joint may be a weld.
(7) In (6) above, the evaluation joint may be a spot weld.

ADVANTAGE OF THE INVENTION According to this invention, the strength test method which can evaluate the strength limit of the evaluation location in a partial structure appropriately can be provided.

1 is a perspective view of a full car model representing the structure of an entire vehicle; FIG. 1 is a front view of a partial structure model according to the first embodiment; FIG. 1 is a front view of an evaluation model according to a first embodiment; FIG. It is an explanatory view of a strength testing device concerning a 1st embodiment. FIG. 11 is a front view of a partial structural model according to the second embodiment; It is a front view of an evaluation model according to the second embodiment. It is explanatory drawing of the strength test apparatus which concerns on 2nd Embodiment.

In the field of automobiles, from the viewpoint of reducing the load on the global environment, there is a demand for lighter vehicles. Therefore, the frame of the vehicle is designed based on high-strength materials and thin plate thickness. Newly designed vehicles are required to assess their impact in a crash as part of their safety assessment. One of the evaluation methods, a test using the entire vehicle (full car test) requires high cost, so a test that evaluates the partial structure using the partial structure of the vehicle that can be performed at a relatively low cost. (partial structural test) is in demand. A test specimen for the partial structure test is required to accurately simulate the partial structure of the vehicle that will be the test specimen for the full car test.
However, in the conventional crash test method, plastic deformation occurs at an early stage in a portion of the partial structure that is different from the desired evaluation point, and it is not possible to apply a specific large load to the designated evaluation point. In some cases, the limits could not be properly evaluated.

For example, a center pillar assembly, which is a partial structure of a vehicle and consists of a center pillar, a roof rail portion joined to the upper end of the center pillar, and a side sill portion joined to the lower end of the center pillar, was used as a test specimen. As a result of the impact test in which an impact load was applied to the test specimen, when plastic deformation occurred earliest at the connection between the center pillar and the side sill, the connection between the center pillar and the roof rail , it becomes difficult for a load larger than the load acting at that time to act. For this reason, since the load cannot be applied to the limit, the limit strength of the joint between the center pillar and the roof rail could not be evaluated.

Accordingly, the present invention provides a strength testing method, comprising: a partial structure model preparation step of preparing a partial structure model simulating a partial structure; a weak point identification step of identifying a weak point in the partial structure model; Includes an evaluation point designation process of designating evaluation points from other points excluding weak points, an evaluation model preparation process of preparing an evaluation model that simulates the evaluation points, and an evaluation test process of applying an excessive load to the evaluation model. . This makes it possible to positively apply a large load to an evaluation point different from the weak point and evaluate the critical strength of the evaluation point. Therefore, it is possible to appropriately evaluate the strength limit of the evaluation portion of the partial structure.
A strength test method according to an embodiment of the present invention will be described below.

(First embodiment)
FIG. 1 is a perspective view of a full car model 1 representing the structure of the entire vehicle. FIG. 2 is a front view of the partial structure model 3 according to the first embodiment. FIG. 3 is a front view of the evaluation model 4 according to the first embodiment. In FIG. 1, the chain double-dashed line represents the center pillar 21 deformed under the action of the specific load L. As shown in FIG.
Hereinafter, the partial structure P is a center pillar assembly composed of a center pillar 21, a portion of a roof rail 23 connected to the upper end of the center pillar 21, and a portion of a side sill 22 connected to the lower end of the center pillar 21. 2, the weak point W is the connection portion between the center pillar 21 and the side sill 22 in the center pillar assembly 2, and the evaluation point E is the evaluation connection portion J between the center pillar 21 and the roof rail 23. A strength test method according to an embodiment will be described in chronological order.

(First strength test method)
(A1) First, as shown in FIG. 1, a full car model 1 representing the structure of the entire vehicle including the partial structure P is subjected to load (impact load, tensile load, compression load), moment, or a combination thereof. Analyze the stress, strain, etc. generated when a specific load L is applied. Then, based on the analysis results, a partial structure model 3 simulating the center pillar assembly 2 (partial structure P) as shown in FIG. 2 is prepared (partial structure model preparation step).
The partial structure model 3 is a substantial part that looks like a center pillar assembly 2 cut out for use in an actual vehicle, in which boundary conditions (constraint conditions and load conditions) are set by simulating constraint conditions using jigs B. It may be a structural model. The jig B can be set to an appropriate rigidity depending on the constraint conditions. The substructure model 3 may be an insubstantial analytical model for computer simulation, such as a finite element model used in the finite element method, in which boundary conditions are set. That is, the partial structure model 3 may be created by converting the center pillar assembly 2 (partial structure P) into a finite element model. As a result, the partial structural model preparation process can be realized without creating a substantive partial structural model.
An actual vehicle may be used instead of the full car model 1 . It should be noted that the partial structure P is not limited to the center pillar assembly 2, and may be a structure including the A-pillar, roof rails, and connecting portions thereof in the structure of the entire vehicle. Note that the partial structure P is not limited to a partial structure for the entire vehicle, and may be a partial structure for another overall structure (for example, a flying object, a ship, etc.).

(A2) Next, a weak point W in the center pillar assembly 2 (partial structure P) is specified (weak point specifying step). To specify the weak point W, a specific load L is applied to the partial structural model 3 to specify the weak point W in the partial structural model 3 . The weak point W is, for example, a connecting portion between the center pillar 31 and the side sill 32 in the partial structure model 3, as shown in FIG. The identification of the weak point W may be performed by a human based on the results of a strength test on the substance, or may be performed by a computer based on the results of a computer-aided design analysis (CAE analysis). In the case of a human, for example, when a specific load L is applied to the partial structural model 3 in a predetermined position and in a predetermined direction, a region where plastic deformation is greatest is identified as the weak point W. When the computer performs, in detail, a specific load L is applied at a predetermined position in a predetermined direction to the partial structure model 3 simulating the center pillar assembly 2 (partial structure P), and strain or stress distribution is calculated. Analysis output as an analysis output is performed, and an area where an index based on the analysis output (for example, strain distribution density representing the degree of concentration of strain in a unit volume) is larger than a predetermined threshold is specified as a weak point W. The analysis output may be displayed in gradation corresponding to the magnitude of strain or stress, as appropriate. Thereby, the weak point W can be identified objectively.

(A3) Next, in the partial structure model 3 simulating the center pillar assembly 2 (partial structure P, see FIG. 1), an evaluation point E is specified from other points excluding the weak point W (evaluation point designation step). . The evaluation point E may be the next weakest point after the weak point W, or may be any point other than the weak point W. The designation of the evaluation point E may be performed by a human or by a computer. The evaluation point E connects, for example, the center pillar portion 41 (first member), the roof rail portion 43 (second member), and the center pillar portion 41 (first member) and the roof rail portion 43 (second member). and an evaluation connection J. Thereby, the strength limit of the evaluation point E in the partial structure model 3 can be evaluated appropriately.

Designation of the evaluation point E by the computer may be performed as follows.
(A31) First, from the first partial structure model, which is the partial structure model 3, a first weak point, which is a weak point W having a predetermined area, is identified by the above-described weak point identification step.
(A32) Next, a second partial structural model is created by modeling the remaining first residual structure after removing the first weak point from the first partial structural model.
(A33) Next, a second weak point having a predetermined region is specified by the above-described weak point specifying step again for the second partial structure model.
(A34) Next, a second residual structure remaining after removing the second weak point from the second partial structure model is modeled to create a third partial structure model.
(A35) Next, a third weak point having a predetermined area is specified again by the above-described weak point specifying step for the third partial structure model.
(A36) Next, a fourth partial structural model is created by modeling a third residual structure remaining after removing the third weak point from the third partial structural model.
(A37) Then, such a sequence is repeated until the n-th partial structure model modeling the (n-1)-th (n-1)-th residual structure becomes smaller than a predetermined region.
In this way, any one or all of the second weak point, the third weak point, .

(A4) Next, an evaluation model 4 that simulates the evaluation point E is prepared (evaluation model preparation step).
The evaluation model 4 is, as shown in FIG. 3, a portion corresponding to the evaluation point E further extracted from the partial structure model 3 (see FIG. 2) simulating the partial structure P. As shown in FIG. The evaluation model 4 is formed at the center pillar portion 41, the roof rail portion 43, the evaluation connection portion J between the center pillar portion 41 and the roof rail portion 43, and the end portion corresponding to the cross section of the member cut out from the partial structure P. and jigs BB1 and BB2.
The evaluation model 4 is an evaluation point E in the center pillar assembly 2 (partial structure P, see FIG. 1) where boundary conditions (constraint conditions and load conditions) are set by simulating constraint conditions using jigs BB1 and BB2. It may be a partial structure model that has a substance that looks like it has been cut out. Note that the jigs BB1 and BB2 can be set to appropriate rigidity depending on the constraint conditions. The evaluation model 4 may be an insubstantial analytical model for computer simulation, such as a finite element model used in the finite element method, in which boundary conditions are set.
Thereby, the joint strength of the evaluation joint J at the evaluation point E can be evaluated. Therefore, the strength limit of the evaluation joint J at the evaluation point E can be properly evaluated. The evaluation connection J may be a weld. When the evaluation joint J is a welded portion, the joint strength of the welded portion at the evaluation point E can be evaluated. The connections may be spot welds. If the evaluation joint J is a spot welded portion, the joint strength of the spot welded portion at the evaluation point E can be evaluated.

(A5) Next, as shown in FIG. 4, an excess load H is given to the evaluation model 4 (evaluation test step). Here, the excess load H is a load larger than the distributed load D acting on the evaluation point E due to the specific load L applied to the center pillar assembly 2 (partial structure P) in the weak point identification step. In other words, the distributed load D is the load acting on the evaluation point E when the specific load L acts on the center pillar assembly 2 and the fragile point W is damaged in the fragile point identification step. Then, in the evaluation test process, the evaluation model 4 is given an excess load H that is larger than the distributed load D. As a result, it is possible to apply a large load to the evaluation point E, which does not act in an actual collision with the vehicle. Therefore, the strength limit of the evaluation point E in the partial structure P can be properly evaluated.

(First strength test device)
The first strength testing device 5 for carrying out the strength testing method will be described.
FIG. 4 shows a perspective view of the first strength testing device 5 according to the first embodiment. In FIG. 4, arrows X, Y, and Z indicate three coordinate axes in a three-dimensional orthogonal coordinate system.
As shown in FIG. 4, the first strength test device 5 is a device capable of applying an excessive load H to the evaluation model 4, which is a substructure model with substance, in the evaluation test process.
The first strength testing apparatus 5 includes a first fixture 51 that supports one end of the evaluation model 4 under a predetermined restraint condition via a jig BB1, and a first fixture 51 that supports the other end of the evaluation model 4 via a jig BB2. A second fixture 52 that supports under a predetermined constraint condition, a cylinder 53 that pulls the other end of the evaluation model 4 in the direction indicated by the white arrow along the X axis, and is provided at the end of the cylinder 53, A chuck 54 that rotatably supports a shaft member 55 and a shaft member 55 that fixes the jig BB2 of the evaluation model 4 are provided. The shaft member 55 is rotatable as indicated by an arrow R around the Y-axis perpendicular to the X-axis.
The jig BB1 is a portion of the roof rail portion 43 that is directly fixed to the first fixture 51, and its rotation and movement are restricted.
The jig BB2 is provided at the end of the center pillar portion 41 and fixed to the shaft member 55 .
In addition, since a moment around the Y-axis is applied to one end of the evaluation model 4, one end of the evaluation model 4 and the other end of the evaluation model 4 are separated by ΔZ in the Z-axis direction.

Then, when the other end of the evaluation model 4 is pulled by the cylinder 53 in the direction indicated by the white arrow along the X axis with the excess load H, the one end of the evaluation model 4 and the other end of the evaluation model 4 are pulled together. Since they are separated by ΔZ, a tensile load in the X-axis direction can be applied to the evaluation model 4 while applying a rotational moment about the Y-axis.
In this manner, the first strength testing apparatus 5 can be used to implement the strength testing method according to the present embodiment.

In this way, even if the specific load L is applied to the partial structure P, the weak point W is deformed, and only a relatively small distributed load D is applied to the evaluation joint J. According to the strength test method and the first strength test device 5, the tensile load in the X-axis direction acting on the evaluation model 4 is applied to the partial structure P in the weak point identification process, and the specific load L applied to the partial structure P is applied to the evaluation point E Given an excess load H greater than the distribution load D acting on the evaluation connection J, a load greater than the distribution load D can be applied to the evaluation connection J, for example a load so great as to cause the evaluation connection J to break. Therefore, the strength limit of the evaluation point E or the evaluation joint J in the partial structure P can be evaluated appropriately.

(Second embodiment)
Next, the strength testing method according to the second embodiment and the second strength testing apparatus 8 for carrying out the strength testing method according to the second embodiment will be described. In addition, hereinafter, the description of the parts common to the strength test method according to the first embodiment or the first strength test apparatus 5 for carrying out the strength test method according to the first embodiment may be omitted.
FIG. 5 is a front view of the partial structural model 6 according to the second embodiment. FIG. 6 is a front view of the evaluation model 7 according to the second embodiment.

(Second strength test method)
(B1) First, as shown in FIG. 1, a full car model 1 representing the structure of the entire vehicle including the partial structure P is subjected to load (impact load, tensile load, compression load, etc.), moment, or a combination thereof. The stress, strain, etc. generated when such a specific load L is applied are analyzed. Based on the analysis results, a partial structure model 6 simulating the center pillar assembly 2 (partial structure P, see FIG. 1) as shown in FIG. 5 is prepared (partial structure model preparation step).
The partial structural model 6 is a substantial part that looks like a center pillar assembly 2 cut out for use in an actual vehicle, in which boundary conditions (constraint conditions and load conditions) are set by simulating constraint conditions using jigs B. It may be a structural model. The jig B can be set to an appropriate rigidity depending on the constraint conditions. Here, the jig B has a predetermined torsional rigidity around the longitudinal direction of the side sill 62 or roof rail 63 . As a result, the jig B is in a state between a state in which it is freely rotatable about its longitudinal direction and a state in which it is restricted in rotation, and is in a state in which it undergoes torsional plastic deformation while providing a predetermined resistance to rotation. Constraint conditions at the boundary of the partial structure P cut out from the structure can be simulated. By using such a jig B, the deformation mode when the specific load L is applied to the partial structure model 6 can be accelerated and conspicuous. The substructure model 6 may be an intangible analytical model for computer simulation, such as a finite element model used in the finite element method, in which boundary conditions are set. That is, the partial structure model 6 may be created by converting the center pillar assembly 2 (partial structure P) into a finite element model. As a result, the partial structural model preparation process can be realized without creating a substantive partial structural model.

(B2) Next, the weak point W in the center pillar assembly 2 (partial structure P) is specified (weak point specifying step). To specify the weak point W, a specific load L is applied to the partial structural model 6 to specify the weak point W in the partial structural model 6 . The weak point W is, for example, a connecting portion between the center pillar 61 and the side sill 62 in the partial structural model 6, as shown in FIG.

(B3) Next, in the partial structure model 6 simulating the center pillar assembly 2 (partial structure P), an evaluation point E is specified from other points excluding the weak point W (evaluation point designation step). The evaluation point E is, for example, the center pillar 61 (first member), the roof rail 63 (second member), and the evaluation joint J that connects the center pillar 61 (first member) and the roof rail 63 (second member). and is a structure having Thereby, the strength limit of the evaluation point E in the partial structure model 6 can be evaluated appropriately.

(B4) Next, an evaluation model 7 that simulates the evaluation point E is prepared (evaluation model preparation step).
The evaluation model 7 is, as shown in FIG. 6, a portion corresponding to the evaluation point E further cut out from the partial structure model 6 (see FIG. 5) simulating the partial structure P. As shown in FIG. The evaluation model 7 corresponds to the center pillar portion 71, the roof rail portion 73, the evaluation connection portion J between the center pillar portion 71 and the roof rail portion 73, and the member cross section at the position cut out from the partial structure P (see FIG. 1). and jigs BB1 and BB2 formed at the ends.
The evaluation model 7 is such that an evaluation point E in the center pillar assembly 2 (partial structure P) is cut out, where boundary conditions (constraint conditions and load conditions) are set by simulating constraint conditions using jigs BB1 and BB2. It may be a substructure model with substance.

(B5) Next, as shown in FIG. 7, an excess load H is given to the evaluation model 7 (evaluation test step). Then, in the evaluation test step, the evaluation model 7 is given an excess load H that is larger than the distributed load D. As a result, it is possible to apply a large load to the evaluation point E, which does not act in an actual collision with the vehicle. Therefore, the strength limit of the evaluation point E in the partial structure P can be properly evaluated.

(Second strength test device)
Next, the second strength testing device 8 for carrying out the strength testing method will be described.
FIG. 7 shows a perspective view of a second strength testing device 8 according to the second embodiment. In FIG. 7, arrows X, Y, and Z indicate three coordinate axes in a three-dimensional orthogonal coordinate system.
As shown in FIG. 7, the second strength test device 8 is a device capable of applying an excess load H to the evaluation model 7, which is a substructure model with substance, in the evaluation test process.
The second strength testing apparatus 8 includes a first fixture 81 that supports one end of the evaluation model 7 under a predetermined restraint condition via a jig BB1, and a first fixture 81 that supports the other end of the evaluation model 7 via a jig BB2. A second fixture 82 that supports under a predetermined constraint condition, a cylinder 83 that pulls the other end of the evaluation model 7 in the direction indicated by the white arrow along the X axis, and is provided at the end of the cylinder 83, A chuck 84 that supports a shaft member 85 and a shaft member 85 that supports the jig BB2 of the evaluation model 7 are provided. The shaft member 85 passes through a through hole h provided in the jig BB2.
The jig BB1 is a portion of the roof rail portion 73 that is directly fixed to the first fixture 81, and is restricted in rotation and movement.
The jig BB2 is provided at the end of the center pillar portion 71 and supported by the shaft member 85 .
Further, in order to apply a moment around the Z-axis to one end of the evaluation model 7, the center of one end of the evaluation model 7 and the part supported by the shaft member 85 at the other end of the evaluation model 7 are: They are separated by ΔY in the Y-axis direction.

Then, when the other end of the evaluation model 7 is pulled by the cylinder 83 in the direction indicated by the white arrow along the X axis with the excess load H, the center of the one end of the evaluation model 7 and the other end of the evaluation model 7 are pulled. is separated from the point supported by the shaft member 85 by ΔY in the Y-axis direction, it is possible to apply a tensile load in the X-axis direction to the evaluation model 7 while applying a rotational moment around the Z-axis. can.
In this manner, the second strength testing device 8 can be used to implement the strength testing method according to the present embodiment.

As described above, when the specific load L was applied to the partial structure P, the weak point W was deformed, and only a relatively small distributed load D was applied to the evaluation joint J. According to the strength test method and the second strength test apparatus 8 according to the embodiment, the tensile load in the X-axis direction acting on the evaluation model 7 is applied to the partial structure P in the weak point identification process, and the specific load L is applied to the evaluation point. Given an excess load H greater than the distribution load D acting on E, the evaluation connection J can be subjected to a load greater than the distribution load D, for example a load so great as to cause the evaluation connection J to break. Therefore, the strength limit of the evaluation point E or the evaluation joint J in the partial structure P can be evaluated appropriately.

The means for supporting the evaluation model by the strength testing device is not limited to the above means. The means for supporting the evaluation model by the strength test equipment is the X axis, Y axis and Z It can be set for every six degrees of freedom in the orthogonal coordinate system of the three-dimensional space composed of axes.

The strength test method according to the present embodiment includes a partial structure model preparation step of preparing partial structure models 3 and 6 simulating the partial structure P, and a weak point identification step of identifying a weak point W in the partial structure models 3 and 6. , an evaluation point designation step of designating an evaluation point E from other points excluding the weak point W in the partial structure models 3 and 6, an evaluation model preparation step of preparing evaluation models 4 and 7 simulating the evaluation point E, and an evaluation Since the models 4 and 7 include an evaluation test process for applying an excess load H, an excess load H greater than the distributed load D acting on the evaluation point E when the weak point W is damaged is applied to the evaluation point E. can be given, and the strength limit of the evaluation point E in the partial structure P can be evaluated appropriately.

1 Full car model 2 Center pillar assembly 3, 6 Partial structure model 4, 7 Evaluation model 5 First strength test device 8 Second strength test device 11 Actuator 21, 31, 61 Center pillar 22, 32, 62 Side sill 23, 63 Roof rail 41, 71 Center pillar parts 43, 73 Roof rail parts 51, 81 First fixtures 52, 82 Second fixtures 53, 83 Cylinders 54, 84 Chucks 55, 85 Shaft members B, BB1, BB2 Jig D Distributed load E Evaluation Point h Through hole H Overload J Evaluation connection L Specific load P Partial structure R Arrow W Weak point

Claims (7)

A strength test method,
a partial structure model preparation step of preparing a partial structure model simulating the partial structure;
a weak point identifying step of identifying a weak point in the partial structural model;
an evaluation point designation step of designating an evaluation point from a point other than the weak point in the partial structural model;
an evaluation model preparation step of preparing an evaluation model simulating the evaluation point;
and an evaluation test step of applying an excessive load to the evaluation model. in the weak point identifying step, applying a specific load to the partial structure to identify the weak point in the partial structure;
2. A strength test method according to claim 1, wherein in said evaluation test step, said excess load larger than the distributed load acting on said evaluation point is applied by said specific load. 3. The strength test method according to claim 1, wherein said partial structure model preparation step includes converting said partial structure into a finite element model. The weak point identification step performs an analysis for outputting a distribution of strain or stress as an analysis output for the partial structural model,
4. The strength testing method according to any one of claims 1 to 3, wherein an area in which the index based on the analysis output is larger than a predetermined threshold is specified as the weak point. 5. The structure according to claim 1, wherein the evaluation point has a structure including a first member, a second member, and an evaluation connecting portion connecting the first member and the second member. The strength test method according to any one of. 6. The strength testing method according to claim 5, wherein the evaluation connection is a weld. 7. The strength testing method of claim 6, wherein the evaluation connection is a spot weld.

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