JP2022130931A - Method for identifying plate shape, method for evaluating material characteristics, and test piece - Google Patents

Abstract

To easily and accurately carry out a method for identifying the shape of a plate, with which a discretionary stress triaxiality of deformation can be executed by a uniaxial tensile testing machine.SOLUTION: A shape of a plate is such that a principal plane is rectangular and a notch is formed at one point on each of two long sides of the principal plane, the notches having a point symmetrical relationship, with the center of the principal plane as a symmetrical point. The notches assume a shape composed of two lengths of parallel lines extending from the long sides of the principal plane to the inside of the principal plane and a semicircle of radius φ linking the tips of the two lengths of parallel lines. When it is assumed that a tip-to-distance of the semicircles of the two notches is H in the long side direction of the principal plane and W in the short-side direction, a stress triaxiality of deformation when the plate is pulled by a uniaxial tensile testing machine is obtained and a relationship between φ, H and W and the stress triaxiality is obtained in advance, with the shape of the plate identified by the relationship between φ, H and W and the stress triaxiality.SELECTED DRAWING: Figure 1

Description

The present invention provides a method for specifying the shape of a plate material that can be deformed with an arbitrary stress triaxiality with a uniaxial tensile tester, a method for evaluating material properties by a uniaxial tensile axial tester using this method for specifying the plate shape, and a uniaxial tensile tester. It relates to a test piece of plate material used for material property evaluation by a testing machine.

In recent years, with the dramatic progress in computing power of computers, structural analysis such as the finite element method (FEM) is used to implement vehicle design, structural design, performance evaluation, etc. Instead of testing, they are simulating and evaluating on a computer.

In particular, in structural analysis in vehicle design, considering that the vehicle body collides with a collision object at high speed, and that multiple parts interact with the collision object, tension, compression, and bending deformation occur, and collision safety is considered. It is necessary to evaluate performance, strength, and durability with high accuracy. Therefore, as a conventional technique, there is a case where a method of analyzing in consideration of material properties that change for each stress triaxiality is adopted for structural analysis.

The stress triaxiality is a parameter obtained by dividing the hydrostatic stress by the equivalent stress and is defined as follows.

The hydrostatic stress and Mises equivalent stress can be expressed as follows using principal stresses σ ₁ , σ ₂ and σ ₃ , respectively.

When considering material properties that change for each stress triaxiality in structural analysis, there is a known method of considering material properties evaluated by a test evaluation method according to Patent Document 1, for example. In Patent Document 1, the subject is a quantitative and highly reliable method for obtaining material properties related to brittle fracture, and a test piece of a thin steel plate with a notch is pulled uniaxially, and the stress generated in the test piece is measured. A method is disclosed to establish the relationship between axialness and material properties at break.

JP 2015-87311 A

However, in the method disclosed in Patent Document 1, since the stress triaxiality is evaluated by FEM analysis after determining the shape of the test piece, the range of the stress triaxiality field generated in the structural analysis in vehicle design cannot be covered. In other words, in order to cover all the stress triaxiality fields generated in the above structural analysis, it is necessary to determine the necessary range of stress triaxiality in advance in the above structural analysis. It is necessary to determine the shape of the piece. In addition, it is not possible to conduct an evaluation test that can cover all the above ranges only by evaluating the stress triaxiality after preparing the shape of the test piece.

Therefore, the present invention has been made in view of the above-mentioned problems, and provides a method for specifying the shape of a plate material that can perform arbitrary stress triaxiality deformation with a uniaxial tensile tester. Furthermore, the present invention provides a material property evaluation method using a uniaxial tensile axial tester that utilizes this plate shape specification method. Further, the present invention provides a plate specimen for use in material characterization with a uniaxial tensile tester.

The method for specifying the plate shape of the present invention that solves the above problems is a method for specifying the shape of a plate that can be deformed with an arbitrary stress triaxiality with a uniaxial tensile tester,
A plate made of a single material,
The principal plane is rectangular, and one notch is formed on each of the two long sides of the principal plane and has a point-symmetrical positional relationship with the center of the principal plane as a symmetrical point,
The notch portion has a shape consisting of two parallel lines extending from the long side of the main plane to the inside of the main plane and a semicircle with a curvature φ connecting the tips of the two parallel lines,
Using a plate material in which the distance between the tips of the semicircles of the two notches is H in the long side direction of the main plane and W in the short side direction,
The stress triaxiality of deformation is obtained when the two short sides of each of the plate materials with a plurality of combinations of φ, H and W are pulled with a uniaxial tensile tester, and φ, H and W and the stress triaxial The relationship between
The shape and position of the cutout portion at which the stress triaxiality when pulled by a uniaxial tensile tester has an arbitrary value is specified from the relationship between the above φ, H and W and the stress triaxiality.

It is preferable that the method for specifying the plate shape of the present invention be any one of the following.
- Two parallel lines of the notch are parallel to the short side direction of the main plane.
- The stress triaxiality is 0 or more.
- Obtain the relationship between the above φ, H and W and the stress triaxiality using the finite element method.
- H and W above are greater than zero.

Further, the material property evaluation method of the present invention for solving the above problems is a material property evaluation method by a uniaxial tensile axial tester using the plate shape specification method of the present invention,
Identify the shape of the plate that gives an arbitrary value of stress triaxiality when pulled by a uniaxial tensile tester from the method for identifying the plate shape,
A plate made of the material whose properties are to be evaluated and having the specified shape is pulled with a uniaxial tensile tester to obtain the physical properties of the material at the time of breakage,
The above operation is repeated for a plurality of stress triaxialities to determine the relationship between stress triaxiality and material properties.

Preferably, the material property method of the present invention is any of the following.
- The Young's modulus of the material whose properties are to be evaluated is 1000 GPa or less.
・The material for which we want to evaluate the above characteristics is a resin material.
- The Young's modulus of the resin material is 500 GPa or less.
・The physical properties of the material are the load-displacement diagram, breaking strain, breaking stress, or energy absorption rate up to the time equivalent to breakage.

The test piece of the invention for solving the above problems is a test piece of a plate material used for material property evaluation by a uniaxial tensile axial tester,
It consists of a material whose properties you want to evaluate,
The shape is such that the stress triaxiality when pulled by a uniaxial tensile tester is the value you want to evaluate,
It is specified by the method for specifying the plate shape of the present invention.

According to the present invention, it is possible to specify the shape of a plate that can be deformed with an arbitrary stress triaxiality with a uniaxial tensile tester, so even in structural analysis where a complex stress triaxiality field occurs , it is possible to provide a test piece that generates stress triaxiality that can cover the entire stress triaxiality range. Also, by performing a tensile test or a simulation using a plurality of prepared test pieces, the relationship between a plurality of stress triaxialities and material properties at the time of fracture can be obtained.

FIG. 1 is a flow chart showing a step-by-step method for specifying the plate shape. FIG. 2 is a schematic plan view showing the test piece produced in step S101 of FIG. FIG. 3 is a schematic plan view when performing a tensile test simulation by FEM analysis. FIG. 4 is a schematic plan view of the test piece 208 in which a cylindrical coordinate system is set with r as the center-to-center distance of the cutout portions and θ as the angle formed with the horizontal direction. In FIG. 5, the curvature φ of the semicircle at the tip of the notch is fixed to 1 mm, and the stress triaxiality is calculated with respect to the distance W between the tips of the notch in the short side direction and the distance H between the tips of the notch in the long side direction. It is a graph displayed by contour lines. FIG. 6 is a schematic plan view showing the test piece 200 (a) and the test piece 204 (b) subjected to FEM analysis immediately before fracture and the direction of load generated in the test piece. FIG. 7 shows (a) a test piece shape that achieves the target stress triaxiality of 0.5, and (b) a test piece shape that achieves the target stress triaxiality of 0.2, created from the relationship in FIG. is a schematic plan view of the. FIG. 8 shows that the test piece 200, the test pieces 204 and 208 were subjected to tensile test simulation by FEM analysis, and (a) breaking strain, (b) breaking stress and (c) energy absorption were performed for each stress triaxiality. It is the graph which calculated the ratio.

Preferred embodiments of the present invention are described below with reference to the drawings.
FIG. 1 is a flow chart showing a step-by-step method for specifying the plate shape.

In this embodiment, first, a plurality of test pieces are prepared for determining the relationship between the shape of the test piece and the stress triaxiality (step S101).

FIG. 2 is a schematic plan view showing the test piece produced in step S101 of FIG. FIGS. 2(a) to 2(c) exemplify plate-shaped test pieces of the test piece 200, the test piece 204, and the test piece 208, respectively. Note that the test piece 200, the test piece 204, and the test piece 208 are examples of the shape of the test piece produced in this embodiment, and the shape of the test piece produced in step S101 is not limited to these test pieces. is not.

The test piece 200 is formed with notches 202 and 203 whose tips are semicircles with a curvature of φ1 mm in a positional relationship of point symmetry with the center of the principal plane 201 as the point of symmetry. are separated by a distance W of 3 mm in the short side direction. The test piece 204 has cutouts 206 and 207 whose ends are semicircles with a curvature of φ2 mm in a positional relationship of point symmetry with the center of the principal plane 205 as the symmetrical point. are separated by a distance H in the long side direction of 3 mm. The test piece 208 has cutouts 210 and 211 whose ends are semicircles with a curvature of φ3 mm in a positional relationship of point symmetry with the center of the main plane 209 as the point of symmetry. The distance W in the short side direction is 3 mm, and the distance H in the long side direction is 3 mm. Both the distance W in the short side direction and the distance H in the long side direction of the two cutouts are the distances between the tips of the semicircles of the two cutouts.

The shape of the notch is formed by two parallel lines extending from the long side of the main plane to the inner side of the main plane, and a semicircle of curvature φ connecting the ends of the two parallel lines. The two parallel lines do not have to be parallel to the short sides of the principal planes, but if they are parallel to the short sides of the principal planes, the notch part is used to calculate the relationship between the shape of the test piece and the stress triaxiality. This is preferable because it reduces the number of parameters that determine the positional relationship between . The positional relationship of the notches may be separated only in the short side direction of the plate-shaped test piece like the test piece 200, or only in the long side direction of the plate-shaped test piece like the test piece 204. They may be separated, and may be separated by distances W and H in the short side and long side directions of a plate-shaped test piece like the test piece 208, respectively.

The ranges of φ, W, and H are not particularly limited as long as the shape of the test piece can cover the shape of the test piece that generates the desired stress triaxiality in step S105. The material used for the test piece is not limited, but a material whose material properties change with respect to stress triaxiality is preferred. For example, high tensile strength steel with a Young's modulus of 1000 GPa or less and fiber reinforced resin with a Young's modulus of 500 GPa or less are preferably used because the material properties change depending on the generated stress triaxiality.

Subsequently, FEM analysis is performed to determine the relationship between the shape of the test piece and the stress triaxiality by the finite element method (step S102). ANSYS simulation software LS-DYNA (version 971 R10.2.0), which is widely used in academia and industry, can freely define the relationship between stress triaxiality and breaking strain, so this embodiment use this software. However, if there is analysis software and an external program that can consider stress triaxiality, it may be used as FEM analysis.

For example, for each of test pieces 200, 204, and 208, conditions for FEM analysis are set as follows. As for the tensile test speed, it is preferable not to limit the test speed as long as the strain rate dependence can be expressed in the physical properties of the material. For example, a test speed corresponding to a strain rate of about 0.001/ms, which corresponds to a quasi-static speed, to a strain rate of about 1000/ms, which corresponds to an impact speed, is set assuming the use conditions of the target material. The ambient temperature is about −150° C. to about 200° C., preferably about −40° C. to about 80° C. assuming the use environment of the target material. For example, room temperature (23° C.) is used. Also, instead of using FEM analysis, a uniaxial tensile tester may be used to perform the tensile test.

Subsequently, the relationship between the shape of the test piece and the stress triaxiality is obtained (step S103). In this embodiment, since the uniaxial tensile tester is used, the stress triaxiality generated in the test piece is assumed to be greater than or equal to the shear deformation (stress triaxiality 0.0) generated by the uniaxial tensile tester.

Step S103 includes a first step of calculating the stress triaxiality generated in the test piece and a second step of calculating the relationship between the shape of the test piece and the stress triaxiality.

In the first step, the stress triaxiality is calculated for each test piece by the FEM analysis performed in step S102 or by the uniaxial tensile tester. FIG. 3 is a schematic plan view when performing a tensile test simulation by FEM analysis. For the stress triaxiality of the test piece, for example, the average stress triaxiality generated near the fractured portion 301 when the fractured portion 301 occurs in the test piece 300 can be used as a typical stress triaxiality. Alternatively, instead of the average stress triaxiality, the maximum stress triaxiality generated near the fracture location 301 may be used. Table 1 shows the calculation results of the average stress triaxiality occurring in the vicinity of the breaking point for the test piece 200, the test piece 204 and the test piece 208. The material is a fiber-reinforced resin manufactured by Toray Industries, Inc. (modulus of elasticity: 2.7 GPa, strength: 76 GPa), the test speed is 0.005 m/s, and the ambient temperature is 23°C.

When calculating the stress triaxiality, it is preferable to use the FEM analysis because the hydrostatic stress and the Mises equivalent stress can be easily calculated. Alternatively, the stress triaxiality may be calculated by calculating the hydrostatic stress and the Mises equivalent stress from the strain field generated in the experiment using a digital image correlation method or the like.

In the second step, the relationship between the shape of the test piece and the stress triaxiality is calculated. The stress triaxiality distribution generated in the test piece is caused by the curvature φ of the notch portion, the long-side distance H between the notch tips, and the short-side distance W between the notch tips. Therefore, the method of calculating the above relationship is, for example, taking the short-side distance W between the notch tips on the x-axis, the long-side distance H between the notch tips on the y-axis, and the curvature φ of the notch on the z-axis, It is preferable to display contour lines by assuming the values of the stress triaxiality as altitudes.

Instead of the above relationship calculation method, for example, if the above curvature or one of the distances is fixed, one of the parameters of the x to z axes is fixed, and the corresponding axis other than the fixed parameter is projected two-dimensionally. However, the stress triaxiality may be expressed by contour lines.

Alternatively, a cylindrical coordinate system may be set instead of the orthogonal coordinate system. FIG. 4 is a schematic plan view of the test piece 208 in which a cylindrical coordinate system is set with r as the center-to-center distance of the cutout portions and θ as the angle formed with the horizontal direction. For example, a cylindrical coordinate system is set with the center of the notch 210 of the test piece 208 as the origin 400, the distance to the center of the notch 211 is r, the angle with the horizontal direction is θ, and the stress triaxiality may be contoured. For example, the distance r and angle θ are calculated as follows.

Alternatively, a cylindrical coordinate system may be set with the center of the notch 211 as the origin, the distance to the center of the notch 210 may be r, and the angle to the horizontal direction may be θ. The origin 400 may be set at the tip of the notch 210 or 211, and the angle formed with the horizontal direction may be the angle formed with the long side direction of the test piece.

Further, instead of the contour line display, a contour display corresponding to the numerical value of the stress triaxiality may be used.

Steps S101 to S103 are repeated to determine whether the relationship between the shape of the test piece and the stress triaxiality has been clarified (step S104). If it is determined that the above relationship has been clarified, the process proceeds to step S105. If it is determined that the above relationship is not clarified, it is preferable to return to step S101 and increase the number of test pieces. For example, if the numerical spacing of the stress triaxiality between plots is generally coarse, it is preferable to increase the number of specimens so as to create a specimen shape that allows finer spacing between plots. For example, if the stress triaxiality numerical intervals between plots are locally coarse, the number of specimens can be increased so as to create a specimen shape that allows finer intervals between plots of interest. preferable.

In this embodiment, the curvature φ of the semicircle at the tip of the notch portion is fixed to 1 mm, the short side distance W between the notch tips is 0 mm to 12 mm, and the long side direction distance W between the notch tips is 0 mm to 12 mm. A total of 43 cases were carried out in the range up to, and the average stress triaxiality generated near the breaking point of each test piece was calculated.

In FIG. 5, the curvature φ of the semicircle at the tip of the notch is fixed to 1 mm, and the stress triaxiality is calculated with respect to the distance W between the tips of the notch in the short side direction and the distance H between the tips of the notch in the long side direction. A contour line-displayed graph will be exemplified as an example of the present embodiment. 0.2 to 0.6 indicated by contour lines in FIG. 5 indicate stress triaxiality. In addition, the relationship between the shape of the test piece prepared in this embodiment and the stress triaxiality is an example of implementation, and the method and relationship for calculating the relationship between the shape of the test piece and the stress triaxiality are not limited in any way. do not have.

In the method of creating FIG. 5, first, a graph is created in which the x-axis is the short-side distance W between the notch tips and the y-axis is the long-side distance H between the notch tips. Next, based on the stress triaxiality generated in the vicinity of the rupture point of the test piece of each of the above 43 cases, contour lines of the stress triaxiality are created for the above graph. When creating contour lines of stress triaxiality, three-dimensional interpolation from a three-dimensional data set (short-side distance W between notch tips, long-side distance H between notch tips, and stress triaxiality) A script written in Python was used because it can easily draw contour lines. If you have a program that can draw contour lines, you can use it.

Subsequently, the test piece shape is determined from the above relationship (step S105). Note that if the correlation is obtained in advance, steps S101 to S104 may be skipped and steps S105 and onwards may be performed.

In this embodiment, FIG. 5 is used to determine the shape of the test piece that achieves the desired stress triaxiality. The method for determining the shape of the test piece for determining the desired stress triaxiality is determined, for example, according to the guidelines below.

FIG. 6 is a schematic plan view showing the test piece 200 and the test piece 204 subjected to FEM analysis and showing the direction of the load generated in the test piece and the test piece immediately before fracture. When notches are formed on the same axis as in the test piece 200 shown in FIG. 603, and a biaxial tensile deformation (stress triaxiality 0.67) with loading direction 604. On the other hand, when notches are not formed on the same axis as in the test piece 204 shown in FIG. Uniaxial tensile deformation (stress triaxiality 1/3) and shear deformation (stress triaxiality 0 .0) undergoes mixed deformation. From the above, when the target stress triaxiality is close to the biaxial tensile direction, it is sufficient to use a test piece shape in which notches are formed on the same axis. Also, when the desired stress triaxiality is close to shear deformation, a shape of the test piece in which notches are not formed on the same axis may be used.

FIG. 7 shows (a) a test piece shape that achieves the target stress triaxiality of 0.5, and (b) a test piece shape that achieves the target stress triaxiality of 0.2, created from the relationship in FIG. is a schematic plan view of the. For example, when the target stress triaxiality is 0.5, the notch is formed on the same axis because the stress triaxiality of 0.5 is close to the biaxial tensile deformation (stress triaxiality of 0.67). Create the shape of the specimen. Focusing on FIG. 5, in the case of the shape of the test piece in which the notch is formed on the same axis, the curvature φ of the semicircle at the tip of the notch is 1 mm, and the distance W between the tips of the notch in the short side direction is 10.5 mm. 5 mm and 0 mm may be selected for the long-side distance H between the tips of the cutouts. FIG. 7(a) illustrates the shape of the test piece.

For example, when the target stress triaxiality is 0.2, stress triaxiality 0.2 is close to shear deformation (stress triaxiality 0.0), so the long side distance H between the notch tips is emphasized. can be determined by Focusing on FIG. 5, it is sufficient to select 1 mm for the curvature φ of the notch portion, 0 mm for the distance W between the tips of the notch in the short side direction, and 3 mm for the distance H between the tips of the notch in the long side direction. FIG. 7(b) illustrates the shape of the test piece.

Table 2 shows the results of comparing the stress triaxiality obtained by performing FEM analysis on the target stress triaxiality and the test shape obtained by the determination method described above. As shown in Table 2, the target stress triaxiality and the stress triaxiality obtained by the FEM analysis substantially matched. From the above, it was confirmed that the test piece shape determination method obtained by this embodiment is sufficiently accurate.

As described above, according to the present embodiment, it is possible to accurately specify a method for specifying the shape of a plate that can perform arbitrary stress triaxial deformation with a uniaxial tensile tester.

Subsequently, for each test piece, the relationship between the stress triaxiality and the material properties at the time of fracture is determined (step S106).

Evaluation items at the time equivalent to breakage in this embodiment are the load-displacement diagram up to the time equivalent to breakage, breaking strain, breaking stress, or energy absorption rate. The load-displacement diagram up to the time corresponding to breakage is a load-displacement diagram obtained until the test piece breaks. The breaking strain is the strain (%) at the breaking point of the test piece. The breaking stress is the stress at the breaking point of the test piece. The energy absorption rate is the energy (N·m) absorbed by the test piece before it breaks.

As specific examples, material A (non-reinforced resin material manufactured by Toray Industries, Inc. (modulus of elasticity: 1.8 GPa, strength 107 GPa)), material B (fiber-reinforced resin material manufactured by Toray Industries, Inc. (modulus of elasticity: 2.7 GPa, strength 76 GPa)) and C material (fiber reinforced resin material manufactured by Toray Industries, Inc. (elastic modulus: 9.0 GPa, strength: 120 GPa)), the test pieces 200 shown in FIGS. A case where 204 and 208 are used is illustrated. FIG. 8 shows that for each material of A to C, tensile test simulation is performed by FEM analysis on test pieces 200204 and 208, and (a) breaking strain, (b) breaking stress and (c) It is the graph which calculated the energy absorption rate.

As described above, according to the present embodiment, by using a method for specifying the shape of a plate material that can deform with arbitrary stress triaxiality with a uniaxial tensile tester, the physical properties of the material at the time of stress triaxiality and fracture relationship can be easily obtained.

The method for specifying the shape of the plate material, the method for evaluating the material properties, and the test piece of the present invention provide the shape of the test piece that covers all the complex stress triaxiality fields that occur in all simulations such as vehicle design, structural design, and performance evaluation. Specimens can be provided that achieve precisely specified and targeted stress triaxiality, and the relationship between stress triaxiality and material properties can be evaluated.

200 Test piece 201 Principal plane 202 Notch 203 Notch 204 Test piece 205 Principal plane 206 Notch 207 Notch 208 Test piece 209 Principal plane 210 Notch 211 Notch 300 Tensile test simulation performed by FEM analysis Schematic plan view when performing 301 Breaking point 400 Origin 600 in cylindrical coordinate system Center 601 of test piece 200 Load direction 602 Load direction 603 Load direction 604 Load direction 605 Test piece 204 center 606 Load direction 607 Load direction 608 Load direction 609 Load direction 700 Test piece 701 Test piece

Claims (11)

A method for specifying the shape of a plate that can be deformed with an arbitrary stress triaxiality with a uniaxial tensile tester,
A plate made of a single material,
The principal plane is rectangular, and one notch is formed on each of the two long sides of the principal plane and has a point-symmetrical positional relationship with the center of the principal plane as a symmetrical point,
The cutout portion has a shape consisting of two parallel lines extending from the long side of the main plane to the inside of the main plane and a semicircle with a curvature φ connecting the tips of the two parallel lines,
Using a plate material in which the distance between the tips of the semicircles of the two notches is H in the long side direction of the main plane and W in the short side direction,
The stress triaxiality of deformation is obtained when the two short sides of each of the plate materials with a plurality of combinations of φ, H and W are pulled with a uniaxial tensile tester, and φ, H and W and the stress triaxial The relationship between
The shape and position of the notch at which the stress triaxiality when pulled by a uniaxial tensile tester is an arbitrary value is specified from the relationship between the φ, H and W and the stress triaxiality.
How to identify plate shape. 2. The method of specifying a plate material shape according to claim 1, wherein two parallel lines of said notch are parallel to the direction of the short side of said main plane. 3. The method of specifying a plate shape according to claim 1, wherein said stress triaxiality is 0 or more. 4. The method for specifying a plate shape according to any one of claims 1 to 3, wherein the relationship between said φ, H and W and the stress triaxiality is determined using the finite element method. 5. The method of specifying a plate material shape according to any one of claims 1 to 4, wherein said H and W are greater than 0. A material property evaluation method using a uniaxial tensile axial tester using the plate shape specification method according to any one of claims 1 to 5,
Identify the shape of the plate material that gives an arbitrary value of stress triaxiality when pulled by a uniaxial tensile tester from the method for identifying the plate shape,
A plate made of a material whose properties are to be evaluated and having the specified shape is pulled with a uniaxial tensile tester to obtain the physical properties of the material at the time of breakage,
Repeating the above operation for a plurality of stress triaxialities to determine the relationship between stress triaxiality and material properties;
Material characterization methods. 7. The method of evaluating material properties according to claim 6, wherein the material whose properties are to be evaluated has a Young's modulus of 1000 GPa or less. 8. The material property evaluation method according to claim 6, wherein said material whose property is to be evaluated is a resin material. 9. The material property evaluation method according to claim 8, wherein the Young's modulus of said resin material is 500 GPa or less. 10. The material property evaluation method according to any one of claims 6 to 9, wherein said material property is a load-displacement diagram up to the time equivalent to breakage, breaking strain, breaking stress, or energy absorption rate. A test piece of a plate material used for material property evaluation by a uniaxial tensile axial tester,
It consists of a material whose properties you want to evaluate,
The shape is such that the stress triaxiality when pulled by a uniaxial tensile tester is the value you want to evaluate,
The shape is specified by the plate shape specifying method according to any one of claims 1 to 5,
Test pieces.

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