JP7445130B2 - Shear deformation characteristics evaluation method - Google Patents

Description

The present invention relates to a method for evaluating shear deformation characteristics.

In the conventional evaluation method for shear deformation, a flat test piece is held at two places, and these places are moved in different directions in a plane parallel to the plate surface of the test piece. Shear deformation occurred in some parts.

However, with the conventional method of deforming a simple rectangular test piece by grasping its ends, it has not been possible to appropriately evaluate the shear deformation of the material forming the test piece. In such conventional testing methods, before the material forming the test piece reaches the limit of shear deformation, a load is applied to the test piece outside the evaluation range of shear deformation (for example, at the gripping part or the end of the test piece) where shear deformation occurs. In some cases, the thickness of the plate is locally reduced due to the concentration of the metal, which may cause cracks or breaks in the material. Therefore, measurement became impossible before the shear deformation reached its actual limit, and the amount of strain measured at this point was taken as the amount of shear strain of the test piece.

Conventionally, there have been various attempts to solve such problems. For example, Patent Document 1 discloses a measurement method in which shear characteristics are measured by applying force to a test piece in which a cut has been made, while the test piece is restrained so as not to deform other than the cut portion.

Japanese Unexamined Patent Publication No. 59-193336

The present inventors investigated and found that when the method of Patent Document 1 is applied to a test piece with high strength and small plate thickness, the cut at the end of the test piece is deformed and easily breaks due to stress concentration. Then, we came to the idea that there was a need for a method that could more easily evaluate shear deformation characteristics with high accuracy without requiring complicated processing of test pieces.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a shear deformation characteristic evaluation method, an evaluation device, and a shear deformation characteristic evaluation test piece that can obtain highly accurate shear deformation evaluation characteristics. shall be.

(1) The shear deformation characteristic evaluation method according to one aspect of the present invention includes:
A method for evaluating shear deformation characteristics of a material forming a test piece by causing shear deformation in a test piece, the method comprising:
forming on the test piece a flat part, and a first restraining surface and a second restraining surface connected via the flat part and inclined with respect to the flat part;
a first range spanning the flat portion, the first restraining surface, and the second restraining surface; a second range spanning the flat portion, the first restraining surface, and the second restraining surface and adjacent to the first range; A wall is formed between the first range and the second range by relatively moving in parallel in a direction of displacement inclined with respect to the plane part, and
When moving the first range and the second range in parallel in the displacement direction, shearing and deforming the wall by flowing material from the second range toward the wall;
The present invention is characterized in that the shear deformation characteristics of the shear deformed portion of the wall portion are evaluated.
(2) In the shear deformation characteristic evaluation method described in (1) above,
The evaluation may be performed by changing the angle formed between the flat portion and the first restraining surface.
(3) In the shear deformation characteristic evaluation method described in (1) or (2) above,
The evaluation may be performed by changing the angle between the plane portion and a reference line parallel to the displacement direction.
(4) In the shear deformation characteristic evaluation method described in (1) above,
In the direction in which the first restraint surface and the second restraint surface are lined up, a plurality of the flat parts may be formed, and adjacent flat parts may be inclined to each other.
(5) In the shear deformation characteristic evaluation method described in (4) above,
The angle formed by the first restraining surface and the flat part adjacent to the first restraining surface may be different from the angle formed by the second restraining surface and the flat part adjacent to the second restraining surface. .

The present invention can provide a shear deformation characteristic evaluation method, an evaluation device, and a shear deformation characteristic evaluation test piece that allow highly accurate shear deformation evaluation characteristics to be obtained.

FIG. 2 is a schematic perspective view showing an example in which a plane, a first restraint surface, and a second restraint surface are formed by deforming the test piece according to the first embodiment of the present invention. It is a schematic perspective view showing an example of a first range and a second range. It is a schematic perspective view for demonstrating the state in the middle of forming a wall part. FIG. 2 is a schematic perspective view of a test piece in which a wall portion is formed by moving the first range and the second range in parallel to a predetermined position. FIG. 3 is a schematic view of the test piece viewed from a direction parallel to the plate surfaces of the flat portion, the first restraining surface, and the second restraining surface, and is a side view for explaining the angle θ. FIG. 3 is a schematic view of the test piece viewed from a direction parallel to the plate surfaces of the flat portion, the first restraining surface, and the second restraining surface, and is a side view for explaining the angle α. FIG. 2 is a schematic perspective view of a test piece in which two wall portions are formed by moving a first range and a second range in parallel. It is a schematic perspective view for demonstrating the structure of the upper unit which is a part of evaluation apparatus based on 3rd embodiment of this invention. It is a schematic perspective view for demonstrating the structure of the lower unit which is a part of evaluation apparatus based on 3rd embodiment of this invention. It is a schematic perspective view for explaining the evaluation device concerning a third embodiment of the present invention, and is a sectional view of the evaluation device showing a state in which a test piece is placed. 11 is a cross-sectional view of the evaluation device 1000 in the state shown in FIG. 10 when viewed from a plane parallel to the press direction at the A-A' position. It is a schematic perspective view for explaining the evaluation device concerning a third embodiment of the present invention, and is a sectional view of the evaluation device showing a state where the test piece is deformed. FIG. 13 is a cross-sectional view of the evaluation device 1000 in the state shown in FIG. 12 when viewed from a plane parallel to the press direction at the A-A' position. It is a schematic perspective view for explaining the evaluation device concerning a third embodiment of the present invention, and is a sectional view of the evaluation device showing a state in which a wall portion is formed on a test piece to cause shear deformation. FIG. 15 is a cross-sectional view of the evaluation apparatus 1000 in the state shown in FIG. 14 when viewed from a plane parallel to the press direction at the A-A' position. It is a graph showing the FLD distribution according to the example, and is a graph showing an example in which the shear strain region is adjusted by changing the angle α. It is a graph showing the FLD distribution according to the example, and is a graph showing an example in which the angle α is adjusted so that the distribution is in a pure shear region. 17 is a graph showing the FLD distribution according to the example, and is a graph showing an example in which the shear strain region is adjusted in a direction different from that in FIG. 16 by changing the angle α. FIG. 3 is a diagram for explaining maximum principal strain ε1 and minimum principal strain ε2. It is a graph showing the FLD distribution according to the example, and is a graph showing an example in which the amount of shear strain is adjusted when a mold with an angle θ of 93° is used. It is a graph showing the FLD distribution according to the example, and is a graph showing an example in which the amount of shear strain is adjusted when a mold with an angle θ of 112.5° is used. It is a graph showing the FLD distribution according to the example, and is a graph showing an example in which the amount of shear strain is adjusted when a mold with an angle θ of 128° is used.

Hereinafter, embodiments of the present invention will be described using examples, but it is obvious that the present invention is not limited to the examples described below. In the following description, specific numerical values and materials may be illustrated, but other numerical values and materials may be applied as long as the effects of the present invention can be obtained. Moreover, each component of the following embodiments can be combined with each other.

[First embodiment]
The shear deformation characteristic evaluation method according to the present embodiment is a method for evaluating the shear deformation characteristics of a material forming the test piece by causing shear deformation in a test piece, and the method includes: , and form a first restraining surface and a second restraining surface that are inclined with respect to the flat part, and a first range extending over the flat part, the first restraining surface, and the second restraining surface; The distance between the first range and the second range by relatively moving the first range and the adjacent second range across the first restraint surface and the second restraint surface in parallel in the displacement direction inclined with respect to the plane part. At the same time, when the first range and the second range are moved in parallel in the displacement direction, the material is caused to flow from the second range toward the wall, thereby shearing and deforming the wall. Evaluate the shear deformation characteristics of the shear deformed part of the section.

In the shear deformation characteristic evaluation method having the above configuration, a wall portion is formed by relative translation of the first range and the second range including a part of the plane portion, the first restraint surface, and the second restraint surface. , shear deformation occurs in this wall. At this time, the first range, which is not subject to evaluation, is suppressed from deformation by being sandwiched between the upper and lower molds as described later. Even if cracks occur at the gripping part or the end of the test piece, which are not the target, the test piece does not crack, and highly accurate shear deformation characteristics can be obtained.

Examples of test pieces include metal plates such as steel plates, aluminum alloy plates, and titanium alloy plates. When the test piece is a steel plate, for example, a steel plate having a tensile strength of 590 MPa to 1900 MPa can be preferably applied. When the test piece is a steel plate, for example, it can be preferably applied to a steel plate with a thickness of 1.2 mm to 3.0 mm.

Although the shape of the test piece is not limited, a flat test piece is preferably used.

FIG. 1 is a schematic perspective view showing an example of a deformed test piece according to this embodiment.
In the shear deformation characteristic evaluation method according to the present embodiment, as shown in FIG. 102 and a second restraint surface 103. The plane part 101 is connected to the first restraining surface 102, and the plane part 101 and the first restraining surface 102 are inclined to each other. The plane part 101 is connected to the second restraint surface 103, and the plane part 101 and the second restraint surface 103 are inclined to each other.

In the example of this embodiment, a case where the first restraint surface 102 and the second restraint surface 103 are parallel will be described as an example, but the first restraint surface 102 and the second restraint surface 103 are mutually parallel. It may be inclined.

In this way, a test piece 100 formed to have a flat part 101 and a first restraint surface 102 and a second restraint surface 103 connected through the flat part 101 and inclined with respect to the flat part 101, It may also be referred to as a test piece for evaluating shear deformation characteristics.

Next, as shown in FIG. 2, regarding the above test piece 100, a first range 104 extending over the flat part 101, the first restraining surface 102, and the second restraining surface 103, and a first range 104 extending over the flat part 101, the first restraining surface 102, and the second restraining surface 103, A first range 104 and an adjacent second range 105 are set across the two restraint surfaces 103.

Then, by relatively moving the first range 104 and the second range 105 in parallel in the displacement direction A inclined with respect to the plane part 101, a wall part 106 is created between the first range 104 and the second range 105. form.

FIG. 3 is a schematic perspective view for explaining a state in the middle of forming the wall portion 106. As shown in FIG. 3, a part of the plane part 101, the first restraint surface 102 and the second restraint surface 103 located in the first range 104, and a part of the plane part 101 and the first restraint surface 102 located in the second range 105. and a part of the second restraint surface 103 are relatively moved in parallel, thereby forming the wall portion 106.

At this time, out-of-plane deformation is prevented by holding the material forming part of the plane part 101, first restraint surface 102, and second restraint surface 103 with upper and lower molds from the second region 105 toward the wall part 106. Flow with restraint or restraint. With such flow of the material, the wall portion 106 is formed, and a portion where shear deformation occurs is formed in a portion of the wall portion 106.

FIG. 4 is a schematic perspective view of the test piece 100 in which the first range 104 and the second range 105 are moved in parallel to a predetermined position to form the wall portion 106 to a predetermined height.

By translating the first range 104 and the second range 105 in the displacement direction A inclined with respect to the plane part 101, a shear deformation part 107 in the range indicated by diagonal lines is formed in the wall part 106. The shear deformation portion 107 is mainly formed by a part of the material of the plane portion 101 flowing toward the wall portion 106 .

Note that, depending on the angle formed between the plate surface of the first restraining surface 102 or the second restraining surface 103 and the displacement direction A, shear deformation occurs also in the portions of the wall portion 106 other than the shear deformation portion 107. For example, in the example shown in FIG. 4, shear deformation also occurs in portions of the wall portion 106 other than the shear deformation portion 107.

By deforming the test piece 100 using the method described above, a shear deformation portion 107 can be formed in the wall portion 106, and the test piece 100 can be caused to undergo shear deformation.

In the shear deformation characteristic evaluation method according to the present embodiment, during the formation of the wall portion 106, the thickness of the test piece 100 does not decrease or hardly decreases in the shear deformation portion 107 and the wall portion 106 around the shear deformation portion 107. occurs. This is because the first restraint surface 102 and the second restraint surface 103 adjacent to the plane part 101 were provided in advance before the wall part 106 was formed. When the wall portion 106 is formed, a part of the material of the flat portion 101 flows toward the wall portion 106 to form a shear deformation portion 107. Similarly, the first restraining surface 102 and the shear deformation portion 107 are formed. A portion of the second restraint surface 103 flows toward the wall portion 106. As a result, a wall portion 106 having the same plane as the shear deformation portion 107 is also formed around the shear deformation portion 107 . By having the first restraint surface 102 and the second restraint surface 103 that are inclined with respect to the flat part 101, these first restraint surface 102 and second restraint surface 103 can apply an appropriate force to the material of the test piece 100 that is in the process of being deformed. When gripped, the material flows appropriately, and local reduction in plate thickness can be suppressed. Therefore, shear deformation can be caused in the test piece 100 without reducing or hardly reducing the thickness in the range where the shear deformation of the test piece 100 occurs and its surroundings.

According to the shear deformation characteristic evaluation method according to the present embodiment, no cracks occur in the test piece even under conditions where cracks would occur in conventional testing methods. Therefore, it is possible to generate shear deformation exceeding the amount of shear deformation that was conventionally considered the limit of testing, and the inherent deformation strain of the material can be evaluated with high accuracy.

More specifically, in the shear deformation characteristics evaluation method according to the present embodiment, the presence or absence of cracks in the test piece 100 can be detected as the shear deformation characteristics of the test piece 100. Therefore, the shear deformation limit of a test piece can be accurately measured based on the presence or absence of cracks in the test piece when shear deformation under predetermined conditions is caused in the test piece.

As described above, in the conventional testing method, cracks occur outside the evaluation range of shear deformation before the material forming the test piece reaches the limit of shear deformation. However, in the shear deformation characteristic evaluation method according to the present embodiment, it is possible to cause shear deformation to exceed the amount of strain at which cracking occurs in the conventional test method, so that the limit of shear deformation of the test piece can be more accurately reflected.
For example, even if a material is subject to a strain limit of a certain amount in the pure shear region due to the occurrence of cracks in conventional testing methods, the shear deformation characteristic evaluation method according to this embodiment can be used to determine the amount of strain. Since cracks do not occur even in the case of high strain, higher strains can be measured with higher accuracy.

For example, in the shear deformation characteristic evaluation method according to the present embodiment, evaluation may be performed by changing the angle θ between the plane portion 101 and the first restraining surface 102. This allows the amount of shear strain to be adjusted. Being able to adjust the amount of shear strain has the advantage that it is possible to evaluate the desired strain that is to be measured as a criterion for determining the actual product, such as whether or not the actual product can be manufactured into a desired shape.

FIG. 5 is a schematic side view of the test piece 100 viewed from a direction parallel to the plate surfaces of the flat portion 101, the first restraining surface 102, and the second restraining surface 103. As shown in FIG. 5, among the angles formed by the plane portion 101 and the first restraining surface 102, the smaller angle is defined as θ.

Furthermore, in the shear deformation characteristic evaluation method according to the present embodiment, evaluation may be performed by changing the angle α between the plane portion 101 and a reference line parallel to the displacement direction A.

This allows the shear strain region to be adjusted. Being able to adjust the shear strain region has the advantage that it is possible to evaluate the desired strain that is to be measured as a criterion for determining the actual product, such as whether or not the actual product can be manufactured into the desired shape.

FIG. 6 is a schematic view of the test piece 100 viewed from a direction parallel to the plate surfaces of the flat portion 101, the first restraining surface 102, and the second restraining surface 103, and the displacement direction A is indicated by an arrow. As shown in FIG. 6, among the angles formed by the plane portion 101 and the reference line a parallel to the displacement direction A, the smaller angle is α. The displacement direction A is parallel to the paper plane of FIG.

In the above-described embodiment, an example has been described in which the wall portion 106 is formed between the first range 104 and the second range 105. However, as shown in FIG. 7, two second ranges 105 may be provided on both sides of the first range 104, and two wall parts 106 and a shear deformation part 107 may be formed.

(Measurement of shear deformation limit)
By performing the shear deformation characteristic evaluation method according to the above embodiment while changing the shear deformation angle of the shear deformation occurring in the wall portion 106 of the test piece 100, the limit conditions of shear deformation of the material forming the test piece are evaluated. be able to.

Specifically, the angle (angle θ) between the flat part 101 and the first restraining surface and the angle (angle α) between the flat part 101 and the reference line parallel to the displacement direction A are changed multiple times. By evaluating the relationship between these angles and cracking of the test piece, it is possible to determine the amount of shear strain and shear area under various conditions.

As a method for determining the amount of shear strain at the shear deformation limit, for example, the following procedure is preferable. First, set the angle α between the flat part 101 and a reference line parallel to the displacement direction A, and while maintaining this angle α, set the angle θ between the flat part 101 and the first restraint surface 102 to 90° or more. The angle is changed by 10 degrees within a range of less than 180 degrees, and the test is performed in the order of increasing angles, starting from the smallest angle θ. Then, the shear strain amount is calculated from the stroke amount at the angle θ at which the crack occurs. Since the stroke amount is equal to the amount of movement of the mold, the actual value of the amount of movement of the mold may be used as the stroke amount. Alternatively, the stroke amount may be calculated by computer simulation. Incidentally, the angles α and θ may be calculated in advance by computer simulation according to the evaluation method according to the present embodiment so as to fall within a range in which a desired shear deformation can be obtained.

Further, as described above, by changing the angle α between the plane portion 101 and the reference line parallel to the displacement direction A, the shear strain region can be adjusted. Therefore, we simulate various forms of shear deformation in the shear strain range (uniaxial compression to uniaxial tension), which cannot be measured using conventional evaluation methods, and, for example, evaluate the amount of shear strain in any shear deformation state. be able to.

By the above-described procedure, the amount of shear strain at the shear deformation limit of the material of the test piece to be tested and the amount of shear strain over a wide range can be measured with high accuracy.

Note that the shear deformation angle and the shear deformation strain amount are determined by experimentally measuring the shear deformation portion 107 of the wall portion 106 by marking the actual test piece with etching, targets, dots, scribed circles, etc., and observing the deformation. It may be determined by CAE (Computer Aided Engineering) analysis based on numerical values such as the angle θ and the angle α obtained by the method or the evaluation method described above.

[Second embodiment]
Next, other embodiments of the present invention will be described.

The shear deformation characteristic evaluation method according to the present embodiment is a method for evaluating the shear deformation characteristics of a material forming the test piece by causing shear deformation in a test piece, and the method includes: , and form a first restraining surface and a second restraining surface that are inclined with respect to the flat part, and a first range extending over the flat part, the first restraining surface, and the second restraining surface; The distance between the first range and the second range by relatively moving the first range and the adjacent second range across the first restraint surface and the second restraint surface in parallel in the displacement direction inclined with respect to the plane part. By forming a wall part in the wall part and flowing the material from the second range towards the wall part when moving the first range and the second range in parallel in the displacement direction, the surface in the wall part or the second range is The wall is subjected to shear deformation while restraining external deformation, and the shear deformation characteristics of the shear deformed portion of the wall are evaluated.
In the shear deformation characteristic evaluation method according to the present embodiment, a plurality of flat parts are formed in the direction in which the first restraining surface and the second restraining surface are lined up, and adjacent flat parts are inclined to each other.

In the shear deformation characteristic evaluation method having the above configuration, a plurality of flat parts are formed in the plane part of the test piece in the direction in which the first restraining surface and the second restraining surface are lined up, and adjacent flat parts are inclined to each other. are doing. Therefore, shear properties under multiple conditions can be evaluated using one test piece.

In the shear deformation characteristic evaluation method according to the present embodiment, the material of the test piece 100 described in the first embodiment can be used.

In addition, in the shear deformation characteristic evaluation method according to the present embodiment, two flat parts (the first A test piece deformed to have a flat part and a second flat part may also be used.

The test piece according to the second embodiment has a first restraining surface, a first plane part, a second flat part, and a second restraining surface in this order in one direction. The first plane part and the second plane part are inclined to each other, the first restraining surface and the first plane part are inclined to each other, and the second plane part and the second restraining surface are tilted to each other.

In the shear deformation characteristic evaluation method according to the present embodiment, in the same manner as in the first embodiment, for a test piece, a first range extending over a first plane part, a second plane part, a first restraining surface, and a second restraining surface. , a second range adjacent to the first range is set across the first plane part, the second plane part, the first restraining surface, and the second restraining surface.

Similarly to the first embodiment, the first range and the second range are moved in parallel relative to each other in the displacement direction B inclined with respect to the first plane part or the second plane part. A wall is formed between the second range and the second range.

In the test piece according to the second embodiment, the first plane part is connected to the first restraining surface and the second plane part. Therefore, the first restraint surface and the second plane part play the roles of the first restraint surface and the second restraint surface described in the first embodiment. Similarly, since the second plane part is connected to the first plane part and the second restraining surface, the first plane and the second restraining surface are connected to the first restraining surface and the second restraining surface explained in the first embodiment. It plays the role of a restraining surface.

That is, when forming the wall, a part of the first plane part flows toward the wall to form the first shear deformation part, and at the same time, a part of the second plane part flows towards the wall. As a result, a second shear deformation portion is formed. During the formation of the wall portion, shear deformation occurs in the first shear deformation portion, the second shear deformation portion, and the surrounding wall portions, with the thickness of the test piece not decreasing or almost not decreasing.

At this time, since the angle between the first plane part and the displacement direction B is different from the angle between the second plane part and the displacement direction B, it is possible to cause shear deformation under two conditions in one test piece. can.

Therefore, in the shear deformation characteristic evaluation according to this embodiment, multiple conditions can be measured with one test piece, so it is possible to measure the shear deformation limit described in the first embodiment with fewer test pieces. can.

The angle formed by the first restraint surface and the plane portion adjacent to the first restraint surface may be different from the angle formed by the second restraint surface and the plane portion adjacent to the second restraint surface. Thereby, information on two or more shear strain amounts can be obtained with one test piece.

[Third embodiment]
Next, an evaluation device according to the present invention will be explained.

The evaluation device according to the present embodiment is an evaluation device for causing shear deformation in a test piece to evaluate the shear deformation characteristics of a material forming the test piece, and has first pressing surfaces parallel to each other. A first upper mold and a second upper mold, a first lower mold that holds the test piece between the first upper mold and the first upper mold, and a second upper mold that holds the test piece between the second upper mold and the second upper mold. The second lower die to be sandwiched, the first upper die, and the first lower die are inclined with respect to the first press surface with respect to the second upper die and the second lower die, and It includes a drive mechanism that allows translation in a displacement direction that intersects the direction toward the mold.

By causing shear deformation in a test piece using the evaluation device having the above configuration, it is possible to evaluate shear deformation characteristics with high accuracy without causing cracks in the test piece.

8 and 9 show schematic perspective views of upper and lower molds that constitute the evaluation device 1000 according to this embodiment.

FIG. 8 is a perspective view for explaining the upper unit 1100 that is a part of the evaluation apparatus 1000. In the example of FIG. 8, the upper unit 1100 includes a first upper die 1110 and two units arranged adjacent to the first upper die 1110 when viewed along the direction intersecting the press surface of the first upper die 1110. two second upper molds 1120.

Further, FIG. 9 is a perspective view for explaining a lower unit 1200 that is a part of the evaluation apparatus 1000. In the example of FIG. 9, the lower unit 1200 includes a first lower die 1210 and two units arranged adjacent to the first lower die 1210 when viewed along the direction intersecting the press surface of the first lower die 1210. two second lower molds 1220.

The first upper die 1110 includes a first press surface 1111, a second press surface 1112, and a third press surface 1113.
The second press surface 1112 and the third press surface 1113 are connected via the first press surface 1111, and the first press surface 1111 and the second press surface 1112 are inclined to each other. Moreover, the first press surface 1111 and the third press surface 1113 are inclined to each other.

In addition, the first upper mold 1110 has a first side surface 1114 and a second side surface 1115 (not shown in the example of FIG. 8) that intersect with the first press surface 1111, the second press surface 1112, and the third press surface 1113, respectively. We are prepared.

The second upper mold 1120 includes a first press surface 1121, a second press surface 1122, and a third press surface 1123.
The second press surface 1122 and the third press surface 1123 are connected via the first press surface 1121, and the first press surface 1121 and the second press surface 1122 are inclined to each other. Moreover, the first press surface 1121 and the third press surface 1123 are inclined to each other.

The first press surface 1111 of the first upper mold 1110 and the first press surface 1121 of the second upper mold 1120 are arranged parallel to each other. Further, the second press surface 1112 of the first upper mold 1110 and the second press surface 1122 of the second upper mold 1120 are also parallel to each other, and the third press surface 1113 of the first upper mold 1110 and the third press surface 1113 of the second upper mold 1120 are parallel to each other. The press surfaces 1123 are also arranged parallel to each other.

The second upper mold 1120 includes a side surface 1124, and the side surface 1124 is arranged parallel to either the first side surface 1114 or the second side surface 1115 of the adjacent first upper mold 1110. Further, a predetermined clearance is provided between the first side surface 1114 and the second side surface 1115 and the side surface 1124.

The first lower die 1210 has a first press surface 1211, a second press surface 1212, and a second press surface 1212, which have shapes corresponding to the first press surface 1111, second press surface 1112, and third press surface 1113, respectively, of the first upper die 1110. Three press surfaces 1213 are provided. The second press surface 1212 and the third press surface 1213 are connected via the first press surface 1211, and the first press surface 1211 and the second press surface 1212 are inclined to each other. Moreover, the first press surface 1211 and the third press surface 1213 are inclined to each other. A test piece can be sandwiched between the first upper mold 1110 and the first lower mold 1210.

Similarly, the second lower die 1220 has a first press surface 1221 and a second press surface that correspond to the first press surface 1121, second press surface 1122, and third press surface 1123 of the second upper die 1120, respectively. 1222 and a third press surface 1223. The second press surface 1222 and the third press surface 1223 are connected via the first press surface 1221, and the first press surface 1221 and the second press surface 1222 are inclined to each other. Moreover, the first press surface 1221 and the third press surface 1223 are inclined to each other. A test piece can be sandwiched between the second upper mold 1120 and the second lower mold 1220.

That is, the first press surface 1211 of the first lower mold 1210 and the first press surface 1221 of the second lower mold 1220 are arranged to be parallel to each other. Further, the second press surface 1212 of the first lower mold 1210 and the second press surface 1222 of the second lower mold 1220 are also parallel to each other, and the third press surface 1213 of the first lower mold 1210 and the third press surface 1213 of the second lower mold 1220 are parallel to each other. The press surfaces 1223 are also arranged parallel to each other.

The first lower die 1210 also has a first side surface 1214 and a second side surface 1215 (not shown in the example of FIG. 9) that intersect with the first press surface 1211, the second press surface 1212, and the third press surface 1213, respectively. We are prepared. The second lower mold 1220 includes a side surface 1224, and the side surface 1224 is arranged to be parallel to either the first side surface 1214 or the second side surface 1215 of the adjacent first lower mold 1210. Further, a predetermined clearance is provided between the first side surface 1214 and the second side surface 1215 and the side surface 1224.

The evaluation device 1000 holds an upper unit 1100 (FIG. 8) that holds a first upper mold 1110 and a second upper mold 1120 as shown in FIGS. 8 and 9, and a first lower mold 1210 and a second lower mold 1220. A lower unit 1200 (FIG. 9) may be provided, and a unit drive mechanism (not shown) for relatively moving the upper unit 1100 and the lower unit 1200 may be provided. This unit drive mechanism allows the first upper mold 1110 and the second upper mold 1120 to be moved relative to the first lower mold 1210 and the second lower mold 1220.

The evaluation device 1000 includes a drive mechanism (not shown) for relatively moving the molds in parallel. With this drive mechanism, the first upper mold 1110 and the first lower mold 1210 are tilted with respect to the first press surface 1111 of the first upper mold 1110 with respect to the second upper mold 1120 and the second lower mold 1220, Moreover, it becomes possible to move in parallel in a displacement direction that intersects the direction from the first upper mold 1110 to the second upper mold 1120. This drive mechanism is, for example, held by the upper unit 1100 or the lower unit 1200, and allows the first upper mold 1110 or the first lower mold 1210 to be moved relative to the second upper mold 1120 or the second lower mold 1220. Good too. Alternatively, this drive mechanism may be able to move the second upper mold 1120 or the second lower mold 1220 relative to the first upper mold 1110 or the first lower mold 1210.

Each of the above drive mechanisms may be a hydraulic pump, an electric actuator, or the like, as long as it can apply a sufficient load to the test piece to cause deformation.

In the above description, for convenience, they are referred to as an upper mold, a lower mold, an upper unit, and a lower unit, but the positional relationship of these structures is not limited to the vertical direction. Further, the first upper mold 1110, the second upper mold 1120, the first lower mold 1210, and the second lower mold 1220 are removable from the upper unit 1100 and the lower unit 1200, respectively, and can be easily attached to molds having different shapes. Can be exchanged.

Next, a test method for causing shear deformation in a test piece using the evaluation device according to this embodiment will be described. 10, 12, and 14 used in the following description are perspective views of the evaluation device 1000 cut along a plane passing through the first press surface 1111, second press surface 1112, and third press surface 1113 of the first upper die 1110. It is a diagram. That is, the actual evaluation device has a structure similar to and symmetrical to the structure shown in these figures, with the cross sections of these figures serving as planes of symmetry.

First, as shown in FIG. 10, the flat test piece 300 described in the first embodiment is placed on the pressing surfaces of the first lower mold 1210 and the second lower mold 1220. At this time, each press surface of the first lower mold 1210 and each press surface of the second lower mold 1220 are arranged on the same plane.

Here, FIGS. 11, 13, and 15 are cross sections of the evaluation apparatus 1000 in the states shown in FIGS. 10, 12, and 14, respectively, when viewed from a plane parallel to the press direction at the AA' position. It is a diagram.

Next, as shown in FIGS. 12 and 13, the upper unit 1100 is moved to the lower unit 1200 side, and a test is performed using the first upper mold 1110 and the first lower mold 1210, and the second upper mold 1120 and the second lower mold 1220. The test piece 300 is deformed by sandwiching the piece 300. At this time, since the pressing surfaces of the first upper mold 1110, the first lower mold 1210, the second upper mold 1120, and the second lower mold 1220 are inclined, the test piece 300 has a flat part 301 and a flat part 301. A first restraint surface 302 and a second restraint surface 303 are formed which are connected via the portion 301 and are inclined with respect to the plane portion 301.

Next, as shown in FIG. 14, while maintaining the positions of the upper unit 1100 and the lower unit 1200, the first upper mold 1110 and the first lower mold 1210 are placed against the second upper mold 1120 and the second lower mold 1220. , the wall portion 306 is formed by moving in parallel in a displacement direction that is inclined with respect to the first press surface 1111 of the first upper mold 1110 and intersects with the direction from the first upper mold 1110 to the second upper mold 1120.

During this parallel movement, the portion of the test piece 300 that is sandwiched between the first upper die 1110 and the first lower die 1210 is sandwiched with a force that prevents the test piece 300 from being deformed out of plane. Further, the portion of the test piece 300 that is sandwiched between the second upper die 1120 and the second lower die 1220 is sandwiched with such force that the portion of the test piece 300 can be moved in the in-plane direction.

Due to such parallel movement of the first upper mold 1110 and the first lower mold 1210 with respect to the second upper mold 1120 and the second lower mold 1220, the first side surface 1114 of the first upper mold 1110 and the second lower mold 1220 are moved. A wall portion 306 of the test piece 300 is formed between the side surface 1224 and the side surface 1224.

Here, a portion of the test piece 300 that is sandwiched between the first upper mold 1110 and the first lower mold 1210 corresponds to the first range described in the first embodiment, and the second upper mold 1120 and the second lower mold The area between 1220 and 1220 corresponds to the second range described in the first embodiment. In other words, the portion of the test piece 300 that is sandwiched between the second upper die 1120 and the second lower die 1220 is sandwiched with such force that the portion of the test piece 300 can be moved in the in-plane direction. As the mold moves in parallel, it flows toward the wall portion 306.

Due to the movement of the mold as described above, a wall portion 306 is formed in the test piece 300 as illustrated in FIG. 14 or 15, and a portion of the wall portion 306 is subjected to shear deformation as described in the first embodiment. A section 307 is formed. Therefore, using this evaluation device 1000, it is possible to cause shear deformation in the test piece 300 and detect the occurrence of cracks in the test piece 300.

Note that a detector (not shown) is connected to the above-mentioned drive mechanism, and a detector (not shown) is connected to the drive mechanism described above, and the detection occurs in any of the molds of the first upper mold 1110, the first lower mold 1210, the second upper mold 1120, and the second lower mold 1220. By detecting the load, it may be possible to measure the stroke amount when a crack occurs in the test piece 300. Here, the stroke amount is the amount of movement of the first upper mold 1110 or the first lower mold 1210 with respect to the second upper mold 1120 or the second lower mold 1220 in the above-mentioned parallel movement direction.

Note that if no cracks occur in the test piece 300, all the parts of the test piece 300 that are sandwiched between the second upper mold 1120 and the second lower mold 1220 are connected to the first side surface 1114 of the first upper mold 1110 and the second lower mold 1220. It flows between the side surface 1224 of the second lower mold 1220.

Note that the side surfaces of the first upper mold 1110, the second upper mold 1120, the first lower mold 1210, and the second lower mold 1220 are driven by a drive mechanism so that the side surfaces are parallel to the displacement direction and have the same thickness as the test piece 300. It may be possible to move in parallel while maintaining the distance. With this configuration, the thickness of the test piece 300 does not decrease or almost decreases between each side of the first upper mold 1110, the second upper mold 1120, the first lower mold 1210, and the second lower mold 1220. It is possible to generate shear deformation without causing any deformation.

Note that as long as the side surfaces are parallel to the displacement direction and maintain a distance equal to the thickness of the test piece 300, the wall portion 306 and the flat portion 301 are not limited to being perpendicular, but may be such that these surfaces are inclined to each other. It may be sheared and deformed.

In the evaluation device 1000 according to the present embodiment, by using a mold in which the first press surface (1111, 1121, 1211, 1221) and the second press surface (1112, 1122, 1212, 1222) have different angles, Evaluation can be performed by changing the angle formed by the plane portion 301 and the first restraint surface 302, that is, the angle θ mentioned above. This allows the amount of shear strain to be adjusted.

In the evaluation device 1000 according to the present embodiment, by tilting the mold, the displacement direction and each first press of the first upper mold 1110, the second upper mold 1120, the first lower mold 1210, and the second lower mold 1220 can be adjusted. The angle formed by the surface (1111, 1121, 1211, 1221), that is, the angle α mentioned above, can be changed. Thereby, evaluation can be performed by changing the angle between the plane portion 301 and the reference line parallel to the displacement direction. This allows the shear strain region to be adjusted.

Furthermore, in the evaluation device 1000 according to the present embodiment, a plurality of first press surfaces are provided in the direction in which the second press surface and the third press surface are lined up in each mold, and adjacent first press surfaces are mutually adjacent to each other. It may be inclined.
By forming and shearing a test piece using such a mold, it is possible to form a plurality of shear deformation parts under different conditions in one test piece as described in the second embodiment.

By using such an evaluation apparatus 1000, a flat test piece can be shear-deformed within a single mold, and shear deformation can be evaluated very easily and accurately. The evaluation device according to this embodiment can be preferably used, for example, in the shear deformation characteristic evaluation method described in the first embodiment or the second embodiment. Moreover, by using the above-described evaluation apparatus 1000, the test piece can be sheared and deformed while ensuring the clearance between the respective molds at a predetermined value.

Note that the first upper mold 1110, second upper mold 1120, first lower mold 1210, and second lower mold 1220 described above can be removed from the upper unit 1100 and the lower unit 1200, and can be replaced with desired molds as appropriate. can.

[Fourth embodiment]
Next, a test piece for evaluating shear deformation characteristics according to the present invention will be explained.

The test piece for evaluating shear deformation characteristics according to the present embodiment is a test piece used for causing shear deformation in the test piece and evaluating the shear deformation characteristics of the material forming the test piece, and is used for evaluating the shear deformation characteristics of the material forming the test piece. , a first restraint surface and a second restraint surface that are connected via a plane part and are inclined with respect to the plane part. This test piece for evaluating shear deformation characteristics is placed on the press surfaces of a mold of a predetermined shape, for example, the first lower mold 1210 and the second lower mold 1220 of the evaluation apparatus 1000 described in the third embodiment, and the shear deformation is performed. may be caused.

The test piece for evaluating shear deformation characteristics having the above configuration is provided with a flat surface, a first restraint surface, and a second restraint surface, so that a part of these planes can be translated in parallel to form a wall containing a shear deformation part. A section can be formed. Therefore, even under conditions that would have caused cracks in conventional testing methods, the test piece does not crack, and the original deformation strain of the material can be obtained with high accuracy.

Examples of the present invention will be described below.

Steel plates having the tensile strength and thickness shown in Table 1 below were prepared for use in the shear deformation test. The steel plate is flat.

(Example A)
In this example, the steel plates in Table 1 were set to have a rectangular shape.

Then, a test was conducted in which each processed steel plate was deformed in the in-plane direction of the test piece to cause shear deformation. That is, in Example A, the test piece was subjected to shear deformation using a conventional method. When cracking occurred during shear deformation, the shear strain amount (principal strain amount) and shear deformation angle under that condition were calculated by CAE analysis. The results are shown in Table 3.

(Example B)
In this example, each steel plate in Table 1 was deformed and sheared by the evaluation method of the present invention using the evaluation apparatus of the third embodiment described above. Each steel plate was subjected to deformation and shear deformation using a mold under the conditions shown in Table 4. The size of each steel plate was 165 mm in width and 190 mm in length. In each test piece, the wall portion extended in the length direction of each steel plate.

As in Example A, when a crack occurred in the test piece during shear deformation, the shear strain amount and shear deformation angle under that condition were calculated by CAE analysis. The results are shown in Table 5.

As can be seen from the comparison between Table 3 of Example A and Table 5 of Example B, when the amount of shear strain was measured using the evaluation method according to the present invention in any of the steel plates, the amount of shear strain was higher than that measured by the conventional test method. I was able to measure the amount.

(Example C)
In this example, the steel plate C in Table 1 was deformed and sheared using the evaluation apparatus of the third embodiment described above. In this example, three types of molds with different angles between the first press surface and the second press surface of the molds were prepared, and the occurrence of cracks in each mold was evaluated. The test was carried out under a deformation region (condition) in which FLD is distributed around the pure shear axis.

Table 6 lists the value of θ, the corresponding crack occurrence status, and the shear strain amount and shear deformation angle calculated by CAE analysis.

From the results in Table 6, in steel plate C, cracking occurred in the test piece when θ was 112.5°, so the shear strain amount and shear deformation angle at this time were taken as the evaluation values for steel plate C.

(Example D)
In this example, the steel plate C in Table 1 was deformed and sheared using the evaluation apparatus of the third embodiment described above. In this example, a mold in which θ is 93° is used, and the first press surface of this mold (the first press surface 1111 of the first upper mold 1110 in FIG. 8 and the first lower mold 1210 in FIG. 9) is used. The inclination angle (angle α) of the first press surface 1211) with respect to the pressing direction was changed to obtain a graph of FLD (Forming Limit Diagram) distribution at each inclination angle. This is shown in FIGS. 16 to 18.

The vertical axis in FIGS. 16 to 18 indicates the maximum principal strain ε1, and the horizontal axis indicates the minimum principal strain ε2. The straight line a in FIGS. 16 to 18 represents the pure shear deformation axis, the straight line b represents the uniaxial tension axis, and the straight line c represents the uniaxial compression axis. That is, the range surrounded by straight lines b and c is a shear strain region.
Moreover, the physical meaning is as follows.
Maximum principal strain (ε1): As illustrated in FIG. 19, this indicates the maximum strain in the tensile direction that occurs when the material is deformed.
Minimum principal strain (ε2): As illustrated in FIG. 19, this indicates the maximum strain in the compressive direction that occurs when the material is deformed.
Pure shear deformation axis: tensile/compressive strain ratio (ε1=-ε2)
Uniaxial tensile axis: tensile/compressive strain ratio (ε1=-2*ε2)
Uniaxial compression axis: tension/compression strain ratio (ε1=-1/2*ε2)

In other words, the graphs in Figures 16 to 18 show the balance of tensile/compressive strain in each part of the test piece, and the closer the strain ratio is to -1 (pure shear axis), the more From the viewpoint of constant volume, the change in plate thickness during deformation is reduced. The ideal state of deformation is distribution on the pure shear deformation axis, and the area on the uniaxial tension side from the pure shear axis has a large strain in the tensile direction, so the plate thickness decreases slightly, and the area on the uniaxial compression side The plate thickness increases.

In FIGS. 16 to 18, black plots indicate distortions in the shear deformation evaluation section, and gray plots indicate distortions in other parts. The black plot corresponds to the shear deformation section in FIG.

In the example of FIG. 16 or 18, the angle α is adjusted so that the distribution is on the straight line b side or the straight line c side, and in the case of the distribution on the b side, the deformation is caused by a slightly large tensile strain, and in the case of the distribution on the c side, the deformation is caused by a slightly compressive strain. It simulates a large deformation of . In the example shown in FIG. 17, the angle α is adjusted so that the distribution lies on the straight line a, simulating a deformed state in which the decrease in plate thickness is extremely small.

As shown in FIGS. 16 to 18, the shear strain region (strain ratio) can be adjusted by changing the inclination angle α of the mold with respect to the pressing direction. As described above, by the shear deformation characteristic evaluation method according to the present invention, it is possible to accurately evaluate the critical shear strain amount in various deformation states at various locations in an actual product using a simple test shape and apparatus.

(Example E)
In this example, the steel plate C was deformed and sheared using the evaluation apparatus of the third embodiment described above. In this example, three types of molds in which θ is 93°, 112.5°, and 128° are used so that the above-mentioned FLD distribution is distributed on or near the pure shear axis (a). , the inclination angle (angle α) of the first press surface of these molds with respect to the press direction was changed. Graphs of FLD distribution in each mold are shown in FIGS. 20 to 22. In FIG. 20, θ is 93°, in FIG. 21, θ is 112.5°, and in FIG. 22, θ is 128°. The notations in FIGS. 20 to 22 are the same as those in FIGS. 16 to 18.

As shown in FIGS. 20 to 22, by using the present invention, the amount of strain in any deformation axis (for example, pure shear) can be adjusted, so there is an advantage that characteristic tests can be performed at the amount of strain that is desired to be evaluated.

According to the present invention, there are provided a shear deformation characteristic evaluation method, an evaluation device, and a test piece for shear deformation characteristic evaluation that allow highly accurate shear deformation evaluation characteristics to be obtained, thereby allowing advance prediction of molding defects such as cracks and shortening of construction period/man-hour reduction. It is extremely useful industrially as it can be used for many purposes.

100, 300 Test piece 101, 301 Plane section 102, 302 First restraining surface 103, 303 Second restraining surface 104 First range 105 Second range 106, 306 Wall section 107, 307 Shear deformation section

Claims (5)

A method for evaluating shear deformation characteristics of a material forming a test piece by causing shear deformation in a test piece, the method comprising:
forming on the test piece a flat part, and a first restraining surface and a second restraining surface connected via the flat part and inclined with respect to the flat part;
a first range spanning the flat portion, the first restraining surface, and the second restraining surface; a second range spanning the flat portion, the first restraining surface, and the second restraining surface and adjacent to the first range; A wall is formed between the first range and the second range by relatively moving in parallel in a direction of displacement inclined with respect to the plane part, and
When moving the first range and the second range in parallel in the displacement direction, shearing and deforming the wall by flowing material from the second range toward the wall;
A method for evaluating shear deformation characteristics, comprising evaluating shear deformation characteristics of a shear deformation portion of the wall portion. 2. The shear deformation characteristic evaluation method according to claim 1, wherein the evaluation is performed by changing the angle formed by the flat portion and the first restraining surface. 3. The shear deformation characteristic evaluation method according to claim 1, wherein the evaluation is performed by changing an angle formed between the plane portion and a reference line parallel to the displacement direction. Shear deformation according to claim 1, characterized in that a plurality of the flat parts are formed in the direction in which the first restraining surface and the second restraining surface are lined up, and the adjacent flat parts are inclined to each other. Characterization methods. The angle formed by the first restraining surface and the flat part adjacent to the first restraining surface is different from the angle formed by the second restraining surface and the flat part adjacent to the second restraining surface. The shear deformation characteristic evaluation method according to claim 4.

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