JP6578986B2 - Specimen holding device - Google Patents

Description

  The present invention relates to a test piece holding apparatus.

  Structures such as bridges are subjected to shear loads according to the conditions of use. When this structure is subjected to a greater shear load than expected, for example, when an earthquake greater than expected occurs, shear cracks occur in structural members such as abutments, and the slope of the bridge surface or falling bridges There is a risk of reaching. In order to prevent the occurrence of such an accident, it is necessary to evaluate the mechanical properties of the structural members.

  However, it is impossible to evaluate the mechanical properties of the structural members of the structure with respect to the actual structure. Therefore, a load form in a structure is simulated by applying a tensile load, a torsion load, or the like to a test piece that simulates an actual component member. The small mechanical test piece is used to evaluate the partial mechanical properties of the structure, and the mechanical properties of the entire structure are estimated based on the evaluation results.

  Examples of the shear property evaluation method include methods described in Patent Documents 1 and 2 and Non-Patent Documents 1 to 3.

  The method described in Patent Document 1 applies a force in a direction parallel to the shear surface of the test piece (so-called misload) by a jig that moves in a direction orthogonal to the axis of the cylindrical test piece. This is a method of applying shear stress. The method described in Patent Document 2 is a method of applying a compressive stress and a shear stress to a test piece by sandwiching a sheet-like test piece with two holding means of a test apparatus and relatively shifting the two holding means. It is.

  The method described in Non-Patent Document 1 is a four-point bending test, and the method described in Non-Patent Document 2 is a three-point bending test. The method described in Non-Patent Document 3 is a method in which a notch is provided in a test piece, and the test piece is compressed to cause shear fracture between these notches.

Japanese Utility Model Publication No. 62-176741 JP 2010-71774 A

Suzuki Tatsuo, Kanno Yoshimasa, Ogawa Masato, “Evaluation of Shear Strength of Si Structures by Asymmetric Four-Point Bending Test Method”, Proc. , P. 719-720 JIS K 7057, “Fiber-Reinforced Plastics – How to Determine Apparent Interlaminar Shear Strength by the Short Beam Method”, established on March 1, 1987 JIS K 7092, “Test method for interlaminar shear strength by notch compression of carbon fiber reinforced plastic”, established on December 20, 2005

  The structural member includes a portion to which not only shear stress but also tensile stress or compressive stress is applied, such as residual stress in a welded portion. Therefore, if a tensile stress or a compressive stress can be applied together with a shear stress, a test simulating a load form in an actual structure can be performed, and more accurate material evaluation can be performed.

  For example, if a tensile stress or a compressive stress can be applied together with a shear stress to a small test piece, there are the following advantages. A test simulating an actual load form can be performed on a small test piece collected from a minute region of the structure so as not to impair the performance of the structure. Thereby, it becomes possible to evaluate the residual strength of the structure itself. In this case, the evaluation can be performed with higher accuracy than a test performed using a simulated test piece simulating a structural member of the structure.

  Conventionally, when applying a shear stress, a tensile stress, or a compressive stress to a test piece, the test piece is held using, for example, a chuck. However, if the test piece is held by the chuck, the test piece may be deformed. Thus, if stress is applied in a state where the test piece is deformed, the accuracy of the material evaluation may be lowered due to the influence of the deformation. In particular, when the test piece is small, the test piece is likely to be deformed, and the accuracy of the material evaluation is likely to be greatly reduced. On the other hand, there is a method using a pin chuck as a method of grasping a small test piece. However, since the small pin chuck is difficult to obtain high dimensional accuracy, the accuracy of material evaluation may be reduced.

  On the other hand, the jig used in the method described in Patent Document 1 cannot move in the axial direction of the test piece. Therefore, neither tensile stress nor compressive stress can be applied to the test piece. Further, in the method described in Patent Document 2, only the entire surface of the sheet-like test piece is sandwiched from both sides by two holding means, and a tensile stress cannot be applied to the test piece.

  Since the method described in Non-Patent Document 1 is a method based on a four-point bending test, and the method described in Non-Patent Document 2 is a method based on a three-point bending test, both tensile stress and compressive stress can be applied. Can not. Also, the method described in Non-Patent Document 3 cannot apply either tensile stress or compressive stress to the portion where shear fracture occurs.

  In the present invention, the test piece can be stably held without being deformed, and a shear stress caused by a so-called misload (hereinafter simply referred to as “shear stress”) is applied to the test piece. It is an object of the present invention to provide a test piece holding device capable of applying a tensile stress or a compressive stress.

  A test piece holding device according to an embodiment of the present invention includes a test section extending in one direction, and a test section that protrudes in a shear direction perpendicular to the extending direction of the test section with respect to the test section. An apparatus for holding a test piece having a pair of holding portions provided at both ends in the extending direction, the first fixing portion holding one of the pair of holding portions, and the shear direction A movably provided first arm, a connecting portion connecting the first fixing portion and the first arm, a second fixing portion holding the other of the pair of holding portions, and the second fixing And a second arm provided integrally with the portion so as to be movable in the extending direction. The first fixing part includes a first stretching direction fixing part that holds the one holding part from both sides in the extending direction, and a first shear direction fixing part that holds the one holding part from both sides in the shearing direction. The second fixing portion includes a second extending direction fixing portion that holds the other holding portion from both sides in the extending direction, and a second shear that holds the other holding portion from both sides in the shearing direction. The first arm has a support portion provided on the opposite side of the second fixing portion when viewed from the first fixing portion in the extending direction. The support part has a support hole formed so as to open toward the first fixed part and extend in the extending direction. The connecting portion is provided in the support hole so as to be fixed to the first fixing portion and extending in the extending direction from the first fixing portion side toward the supporting portion side, and in the extending direction. And a cylindrical linear motion bearing. The shaft member is inserted into the linear motion bearing so that an outer peripheral surface thereof is covered with the linear motion bearing.

  Since the holding device has the above-described configuration, by relatively displacing the first fixing portion and the second fixing portion that respectively hold the pair of holding portions of the test piece in the shear direction of the test portion of the test piece, A shear stress can be applied to the test part. Moreover, a tensile stress or a compressive stress can be applied to the test part by relatively displacing the first fixing part and the second fixing part in the extending direction of the test part.

  A 1st fixing | fixed part and a 2nd fixing | fixed part hold | maintain the holding | maintenance part of a test piece from 4 directions with a shear direction fixing | fixed part and an extending | stretching direction fixing | fixed part. By holding the holding part of the test piece from four directions in this way, at least one of shear stress and tensile stress or shear stress is applied to the test part of the test piece without rotating the holding part of the test piece. can do. Therefore, the test part can be more reliably deformed by a desired stress component, and it becomes possible to perform a highly accurate test for various load forms.

  In addition, by holding the test piece holder from four directions, the test piece can be held without being deformed regardless of the size of the test piece. For example, when a small test piece having a length of several millimeters on one side is used, it is possible to perform highly accurate evaluation even for a minute region on the order of submillimeters.

  A cylindrical linear motion bearing is provided in the support hole of the first arm so as to extend in the extending direction. The linear motion bearing supports the shaft member so as to cover the outer peripheral surface of the shaft member fixed to the first fixed portion. With such a configuration, the linear motion bearing does not restrict movement of the shaft member in the extending direction, but restricts movement in the shearing direction and movement in a direction orthogonal to the extending direction and the shearing direction. Thus, the shaft member can be supported. Thereby, it can prevent that the shaft member fixed to the 1st fixing | fixed part moves relatively to directions other than the said extending | stretching direction with respect to the support part of a 1st arm. Therefore, for example, when the first arm and the second arm are reciprocated relatively in the shearing direction to apply a shear load to the test portion, the first fixing portion extends with respect to the support portion of the first arm. It is possible to prevent relative movement in directions other than the direction. For this reason, when a load in the shear direction is transmitted between the first arm (supporting portion) and the first fixing portion via the connecting portion (linear motion bearing and shaft member), the first arm and the first fixing It can prevent that a vibration generate | occur | produces in a part. As a result, it is possible to suppress the occurrence of disturbance in the waveform of the shear load actually applied to the test unit with respect to the input waveform of the shear load (the waveform of the load input to the first arm or the second arm). Thereby, a desired shear stress can be generated in the test part, and an appropriate test can be performed.

  The connection portion further includes a load cell that is provided between the support portion and the first fixing portion and detects a load acting on the support portion and the first fixing portion in the extending direction, and the support portion Has at least two support holes respectively formed on one side and the other side of the load cell in the shear direction, and the connection portion has at least two linear motion bearings and at least two shaft members. In addition, the linear motion bearing may be provided in each support hole, and the shaft member may be inserted into the linear motion bearing.

  In this configuration, movement of the first fixed portion relative to the support portion in a direction other than the extending direction is restricted by the linear motion bearing and the shaft member provided on one side and the other side of the load cell in the shear direction. Thereby, when giving a shear load to a test part, it can fully suppress that a support part and the 1st fixed part displace relatively to directions other than the above-mentioned extension direction. Therefore, it can fully suppress that the load of the said shearing direction is provided to a load cell. Further, as described above, the linear motion bearing does not regulate the movement of the shaft member in the extending direction. Thereby, when applying the tensile load or the compressive load to the test part, it is possible to prevent the load in the extending direction from being applied to the shaft member. As a result, the load in the stretching direction applied to the test part can be detected with high accuracy by the load cell.

  The linear motion bearing may be filled with a solid lubricant. In this case, when a load in the shearing direction is transmitted from the first arm (supporting portion) to the first fixing portion via the connecting portion (linear motion bearing and shaft member), the first arm and the first fixing portion vibrate. Can be sufficiently prevented. As a result, the occurrence of disturbance in the shear load applied to the test part can be sufficiently suppressed.

  The first stretching direction fixing portion and the second stretching direction fixing portion are respectively opposite to the compression direction fixing portion in contact with the end of the test piece in the stretching direction and the compression direction fixing portion in the stretching direction. You may have the tension direction fixing | fixed part which contacts the said holding | maintenance part from the side.

  With this configuration, when the shear stress and the tensile stress or the compressive stress are applied to the test portion of the test piece, the rotation of the holding portion of the test piece can be more reliably prevented.

  At least one of the first fixing part and the second fixing part is connected to an extension direction driving part that relatively displaces the first fixing part and the second fixing part in the extension direction, and the first fixing part And at least one of the second fixing part may be connected to a shearing direction driving part that relatively displaces the first fixing part and the second fixing part in the shearing direction.

  By relatively displacing the first fixed part and the second fixed part by the stretching direction driving part and the shear direction driving part, a tensile stress or a compressive stress is also applied while applying a shear stress to the test part of the test piece. The configuration can be realized.

  According to the test piece holding apparatus according to the embodiment of the present invention, tensile stress or compressive stress is applied to the test piece together with shear stress in a state where the test piece is stably held regardless of the size of the test piece. be able to.

FIG. 1 is a schematic view of a test piece holding device according to the present invention. FIG. 1 (a) is a plan view of the whole holding device, and FIG. 1 (b) is a portion around the test piece of FIG. 1 (a). An enlarged view is shown. FIG. 2 is a block diagram showing an example of a specific configuration of the test piece holding device of the present invention. FIG. 2 (a) shows a plan view of the whole holding device, and FIG. 2 (b) shows FIG. The partial enlarged view of the 1st fixing | fixed part and 2nd fixing | fixed part of a) is shown. FIG. 3 is a schematic sectional view taken along line III-III of the first arm of FIG. FIG. 4 is a perspective view of a first fixing portion of the holding device shown in FIG. FIG. 5 is a plan view of the first base member. 6 is a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a plan view of a test piece suitable for the test method according to the embodiment of the present invention. FIG. 8 is a configuration diagram of a test piece more suitable for a fatigue test among the test methods according to the embodiment of the present invention. FIG. 8 (a) shows a plan view and FIG. 8 (b) shows a side view. . FIG. 9 is a diagram showing the result of FEM analysis of the case where stress is applied to the test piece shown in FIG. 8 as stress distribution. FIG. 9A shows the case where shear stress is applied, and FIG. ) Shows the case where tensile stress is applied. FIG. 10 is a diagram illustrating the configuration of the holding device used in the shear test of the comparative example. FIG. 11 is a graph showing the waveform of the load input to the second arm and the waveform of the load detected by the second load cell in the shear test of the example. FIG. 12 is a graph showing the waveform of the load input to the second arm and the waveform of the load detected by the second load cell in the shear test of the comparative example.

  Hereinafter, preferred embodiments of a test piece holding apparatus and a test method using the holding apparatus according to the present invention will be described with reference to the drawings. In addition, the dimension of the structural member in each figure does not represent the dimension of an actual structural member, the dimension ratio of each structural member, etc. faithfully.

1. FIG. 1 is a schematic view of a test piece holding device of the present invention, FIG. 1 (a) shows a plan view of the whole holding device, and FIG. 1 (b) shows FIG. The partial enlarged view of the test piece periphery of a) is shown. First, with reference to the schematic diagram of FIG. 1, the structure of the holding | maintenance apparatus of this invention is demonstrated easily.

  As shown in FIG. 1A, the holding device 10 includes a surface plate 11, a first moving body 12, and a second moving body 13. The first moving body 12 and the second moving body 13 are arranged on the surface plate 11. The holding device 10 holds the test piece 60 with the first moving body 12 and the second moving body 13.

  Here, as shown in FIG. 1B, the test piece 60 includes a test portion 61 and a pair of holding portions 62 and 63. The test part 61 is formed so as to extend in one direction (the direction indicated by the arrow A in the figure) at the center of the test piece 60. Hereinafter, the extending direction A of the test unit 61 is referred to as a reference direction A of the test unit 61. In the present embodiment, the reference direction A of the test unit 61 coincides with the longitudinal direction of the test piece 60. In the reference direction A, a holding unit 62 is provided at one end of the test unit 61, and a holding unit 63 is provided at the other end of the test unit 61. The holding parts 62 and 63 protrude in a direction perpendicular to the reference direction A with respect to the test part 61 (a direction indicated by an arrow B in the figure, hereinafter also referred to as “shear direction B”).

  The holding unit 62 is held by the first moving body 12. The holding unit 63 is held by the second moving body 13. The first moving body 12 is configured to be movable in the reference direction A. The second moving body 13 is configured to be movable in the shear direction B. In the holding device 10, a tensile stress or a compressive stress can be applied to the test unit 61 by moving the first moving body 12 in the reference direction A. Further, by moving the second moving body 13 in the shear direction B, a shear stress can be applied to the test unit 61. FIG. 1A shows a state in which the second moving body 13 is displaced in the shear direction B with respect to the first moving body 12 so that shear stress acts on the test unit 61.

  As shown in FIG. 1A, the first moving body 12 includes a first fixing unit 20, a first arm 41, a first load cell 42, and a second load cell 43. The first fixing unit 20 is connected to the first arm 41 by a connection unit 44. In the present embodiment, the first load cell 42, a linear motion bearing 44a described later, and a shaft member 44b described later constitute a connecting portion 44.

  The first fixing portion 20 has a C shape as viewed from above. As shown in FIG. 1B, the first fixing portion 20 is referred to as a compression direction fixing portion 21 (hereinafter simply referred to as the fixing portion 21) and a pair of tension direction fixing portions 22 (hereinafter simply referred to as the fixing portion 22). ) And a pair of shear direction fixing parts 23 (hereinafter simply referred to as fixing parts 23). In FIG. 1A, the first fixing portion 20 is shown in a simplified manner, and the boundary lines between the fixing portion 21, the pair of fixing portions 22, and the pair of fixing portions 23 are not shown. In the present embodiment, the fixing portion 21 and the pair of fixing portions 22 function as a first stretching direction fixing portion, and a fixing portion 31 and a pair of fixing portions 32 described later function as a second stretching direction fixing portion. Moreover, a pair of fixing | fixed part 23 functions as a 1st shear direction fixing | fixed part, and a pair of fixing | fixed part 33 mentioned later functions as a 2nd shearing direction fixing | fixed part.

  As shown in FIG. 1B, the fixing portion 21 is arranged so as to contact the end portion on the holding portion 62 side among the both end portions of the test piece 60 in the reference direction A. The pair of fixing portions 22 are arranged so as to contact the holding portion 62 from the side opposite to the fixing portion 21 in the reference direction A. Further, the pair of fixing portions 22 are arranged so as to sandwich the test portion 61 from both sides in the shear direction B. A pair of fixing | fixed part 23 is arrange | positioned so that the one edge part and the other edge part of the holding | maintenance part 62 in the shear direction B may each contact.

  That is, the fixing part 21, the pair of fixing parts 22, and the pair of fixing parts 23 are arranged so as to surround one holding part 62 of the test piece 60 from four directions. Therefore, the holding part 62 of the test piece 60 is held from four directions by the first fixing part 20. Specifically, the fixing portion 21 and the pair of fixing portions 22 hold the holding portion 62 from both sides in the reference direction A, and the pair of fixing portions 23 hold the holding portion 62 from both sides in the shearing direction B.

  As shown to Fig.1 (a), the 1st arm 41 has the shape bent in the substantially L shape seeing from upper direction. Specifically, the first arm 41 includes a first extending portion 41 a extending in the reference direction A and a second extending portion 41 b extending in the shear direction B. Although details will be described later, one end portion of the first extending portion 41 a in the reference direction A is connected to the first driving unit 40 (extending direction driving unit) via the second load cell 43. Moreover, although mentioned later for details, the 1st fixing | fixed part 20 is connected to the 2nd extending | stretching part 41b via the connection part 44. FIG. In the present embodiment, the second extending portion 41b corresponds to the support portion.

  In the reference direction A, the second extending portion 41b is provided on the opposite side to the second fixing portion 30 described later when viewed from the first fixing portion 20. In the present embodiment, the second extending portion 41 b is provided so as to extend in the shear direction B from the other end portion of the first extending portion 41 a in the reference direction A. The second extending portion 41 b has a support hole 41 c having a circular cross section formed so as to open toward the first fixed portion 20 and extend in the reference direction A. In the present embodiment, the second extending portion 41b has a plurality of (for example, two) support holes 41c. In the present embodiment, each support hole 41c is formed so as to penetrate the second extending portion 41b in the reference direction A.

  The first load cell 42 has a column part 42a. The first fixed portion 20 and the second extending portion 41 b of the first arm 41 are connected via the column portion 42 a of the first load cell 42. That is, the first load cell 42 is connected to the first fixing unit 20 and the first arm 41. The first load cell 42 detects the load acting on the first fixed portion 20 and the first arm 41 in the reference direction A, that is, the magnitude of the load acting on the test portion 61 of the test piece 60 in the reference direction A direction. To do. More specifically, the first load cell 42 detects the magnitude of the tensile load and the compressive load that act on the test unit 61.

  The second load cell 43 has a pillar portion 43a. The first extending part 41 a of the first arm 41 and the first driving part 40 are connected via a pillar part 43 a of the second load cell 43. That is, the second load cell 43 is connected to the first arm 41 and the first drive unit 40. The second load cell 43 detects the load acting on the first fixed portion 20 and the first arm 41 in the shear direction B, that is, the magnitude of the load acting on the test portion 61 of the test piece 60 in the shear direction B. More specifically, the second load cell 43 detects the magnitude of the shear load acting on the test unit 61.

  In addition to the first load cell 42, the connecting portion 44 includes one or more cylindrical (for example, cylindrical) linear motion bearings 44a and one or more columnar (for example, cylindrical) shaft members 44b. Have. In the present embodiment, the connection portion 44 has a pair of linear motion bearings 44a and a pair of shaft members 44b. In the present embodiment, in the shear direction B, the connecting portion 44 is positioned such that the first load cell 42 is positioned between the one linear motion bearing 44a and the shaft member 44b and the other linear motion bearing 44a and the shaft member 44b. Is provided. The columnar shaft member includes not only a solid shaft member but also a hollow (for example, cylindrical) shaft member.

  The linear motion bearing 44a includes, for example, a ball guide. The linear motion bearing 44a is inserted into the support hole 41c of the second extending portion 41b so as to extend in the reference direction A. In the present embodiment, the linear motion bearing 44a is press-fitted into the support hole 41c, for example. Thereby, the linear motion bearing 44a is fixed to the second extending portion 41b. In the present embodiment, one end of the linear motion bearing 44a in the reference direction A is press-fitted into the support hole 41c, and the other end protrudes from the support hole 41c. In the present embodiment, the linear motion bearing 44a is filled with a solid lubricant.

  One end portion of the shaft member 44b in the reference direction A is fixed to the first fixing portion 20. In the present embodiment, the shaft member 44b extends in the reference direction A from the first fixed portion 20 side toward the second extending portion 41b side. The other end side in the reference direction A of the shaft member 44b is inserted into the linear motion bearing 44a. That is, in this embodiment, the linear motion bearing 44a supports the shaft member 44b so as to cover the outer peripheral surface of the other end side of the shaft member 44b. Specifically, the linear motion bearing 44a does not restrict the movement of the shaft member 44b in the reference direction A, moves in the shear direction B, and a direction orthogonal to the reference direction A and the shear direction B (this embodiment). In the embodiment, the shaft member 44b is supported so as to restrict movement in the vertical direction).

  The second moving body 13 includes a second fixing unit 30 and a second arm 51. The second fixing unit 30 is connected to the second driving unit 50 (shear direction driving unit) via the second arm 51. The second arm 51 has one end connected to the second fixing unit 30 and the other end connected to the second driving unit 50.

  The 2nd fixing | fixed part 30 has C shape seeing from upper direction. As shown in FIG. 1B, the second fixing portion 30 is referred to as a compression direction fixing portion 31 (hereinafter simply referred to as the fixing portion 21) and a pair of tension direction fixing portions 32 (hereinafter simply referred to as the fixing portions 32). ) And a pair of shear direction fixing parts 33 (hereinafter simply referred to as fixing parts 33). The fixing unit 31, the fixing unit 32, and the fixing unit 33 are arranged with respect to the holding unit 63 in the same manner as the fixing unit 21, the fixing unit 22, and the fixing unit 23 with respect to the holding unit 62. Therefore, the holding portion 63 of the test piece 60 is held from four directions by the second fixing portion 30. Specifically, the fixing portion 31 and the pair of fixing portions 32 hold the holding portion 63 from both sides in the reference direction A, and the pair of fixing portions 33 hold the holding portion 63 from both sides in the shearing direction B.

  The first drive unit 40 displaces the first moving body 12 in the reference direction A. As a result, the first fixing portion 20 and the second fixing portion 30 are relatively displaced in the reference direction A. The second drive unit 50 displaces the second moving body 13 in the shear direction B. As a result, the first fixing portion 20 and the second fixing portion 30 are relatively displaced in the shear direction B.

  Although not particularly shown, the first drive unit 40 and the second drive unit 50 are both configured to be reciprocally movable along a linear guide provided on the surface plate 11 by a motor or the like.

  In the present embodiment, as shown in FIG. 1B, the first fixing portion 20 includes a fixing portion 21, a pair of fixing portions 22, and a pair of fixing portions 23 as viewed from above. 62 is in contact with the entire portion other than the connection portion C with the test portion 61. That is, the fixing portion 21, the pair of fixing portions 22, and the pair of fixing portions 23 are in contact with the holding portion 62 so as to cover all the side surfaces of the holding portion 62 when viewed from above. However, the fixing portion 21 may be disposed so as to contact at least a part of one end portion in the longitudinal direction of the holding portion 62. Further, each of the pair of fixing portions 22 may be disposed so as to contact at least a part of the other end portion in the longitudinal direction of the holding portion 62. Furthermore, one fixing portion 23 contacts at least a part of one end portion in the shearing direction B of the holding portion 62, and the other fixing portion 23 is at least one of the other end portions in the shearing direction B of the holding portion 62. You may arrange | position so that a part may be contacted. Although the detailed description is omitted, the same applies to the second fixing portion 30.

  However, as in the present embodiment, the fixing portion 21, the pair of fixing portions 22, and the pair of fixing portions 23 of the first fixing portion 20 cover the entire side surfaces of the holding portion 62 as viewed from above. Thus, the holding part 62 is contacted, and the fixing part 31, the pair of fixing parts 32, and the pair of fixing parts 33 of the second fixing part 30 cover all the side surfaces of the holding part 63 as viewed from above. It is preferable to contact the holding part 63 as described above. Thereby, the holding parts 62 and 63 can be held more stably, and more accurate material evaluation can be performed using the holding device 10.

  In the present embodiment, the first fixing unit 20 is displaced in the reference direction A of the test unit 61 as shown in FIG. On the other hand, the second fixing portion 30 is displaced in the shear direction B orthogonal to the reference direction A. However, the first fixing part 20 may be displaced in the shear direction B, and the second fixing part 30 may be displaced in the reference direction A. Further, both the first fixing part 20 and the second fixing part 30 may be displaced in the reference direction A and the shear direction B.

2. Specific Configuration Example of Test Specimen Holding Device In FIG. 1, each component is shown in a simplified manner in order to explain the function of the holding device. Hereinafter, a specific configuration of the holding device will be described with reference to FIGS. 2 to 6.

  FIG. 2 is a block diagram showing an example of a specific configuration of the test piece holding device of the present invention. FIG. 2 (a) shows a plan view of the whole holding device, and FIG. 2 (b) shows FIG. The partial enlarged view of the 1st fixing | fixed part and 2nd fixing | fixed part of a) is shown. 2, the same members as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG. FIG. 2 shows a state in which the holding device 15 holds the test piece 60. Also in FIG. 2, the reference direction A and the shearing direction B are shown as in FIG.

  A test piece holding device 15 shown in FIG. 2A includes a surface plate 11, a first moving body 16, and a second moving body 17. The first moving body 16 includes a first fixing portion 80, a first arm 46, a first load cell 47, and a second load cell 43, and the second moving body 17 includes a second fixing portion 90 and a second arm 56. . In the present embodiment, the first fixing portion 80 is fixed to the first arm 46 by the connection portion 45. In the present embodiment, the connecting portion 45 is constituted by the first load cell 47, a plurality (four in this embodiment) of linear motion bearings 44a, a plurality (four in the present embodiment) of shaft members 44b, and a case 49 described later. Composed.

  The first moving body 16 and the second moving body 17 are specific examples of the configuration of the first moving body 12 or the second moving body 13 in FIG. The first fixing unit 80 and the first load cell 47 are specific examples of the configuration of the first fixing unit 20 or the first load cell 42 in FIG. The second fixing portion 90 is a specific example of the second fixing portion 30 in FIG. The first arm 46 and the second arm 56 are specific examples of the first arm 41 and the second arm 51 in FIG. 1, respectively.

  In the holding device 15, a case 49 is attached between the first fixing unit 80 and the first arm 46 in the reference direction A of the test unit 61.

  The first arm 46 includes a first extending portion 46 a extending in the reference direction A and a second extending portion 46 b extending in the shear direction B. The first extending portion 46a and the second extending portion 46b of the first arm 46 are integrally formed. In the present embodiment, the second extending portion 46b corresponds to the support portion.

  One end of the first extending portion 46 a in the reference direction A is connected to the column portion 43 a of the second load cell 43. The second extending portion 46 b is provided on the side opposite to the second fixing portion 90 when viewed from the first fixing portion 80 in the reference direction A. In the present embodiment, the second extending portion 46 b is provided so as to extend in the shear direction B from the other end portion of the first extending portion 46 a in the reference direction A.

  FIG. 3 is a schematic sectional view taken along line III-III of the first arm 46 of FIG. Referring to FIGS. 2A and 3, the second extending portion 46 b has a recess 46 c that opens toward the first fixing portion 80 side and a plurality (four in this embodiment) of support holes 46 d. In the present embodiment, each support hole 46d has a circular cross section and is formed so as to penetrate the second extending portion 46b in the reference direction A. In the present embodiment, in the shear direction B, two support holes 46d are formed on one side of the recess 46c, and two support holes 46d are formed on the other side of the recess 46c.

  Referring to FIG. 2A, the case 49 includes a storage portion 49 a formed in a rectangular parallelepiped shape, and a flange portion 49 b extending in the shear direction B from one end portion of the storage portion 49 a in the reference direction A. The accommodating part 49a has the recessed part 49c opened toward the 2nd extending | stretching part 46b side. The concave portion 46c of the second extending portion 46b and the concave portion 49c of the accommodating portion 49a are provided so as to face each other in the reference direction A. The case 49 is fixed to the first fixing portion 80 by a bolt (not shown). In the present embodiment, for example, the flange portion 49 b is fixed to the first fixing portion 80.

  The first load cell 47 is accommodated in the recess 46c and the recess 49c. In the present embodiment, the first load cell 47 is fixed to the second extending portion 46b by a bolt 47a. Moreover, although illustration is abbreviate | omitted, the 1st load cell 47 is fixed to the case 49 with a volt | bolt, for example.

  In the present embodiment, the connection portion 45 has four linear motion bearings 44a and four shaft members 44b. Each linear motion bearing 44a is inserted into the support hole 46d of the second extending portion 46b so as to extend in the reference direction A. In the present embodiment, the linear motion bearing 44a is press-fitted into the support hole 46d, for example. Thereby, the linear motion bearing 44a is fixed to the second extending portion 46b. In the present embodiment, one end of the linear motion bearing 44a in the reference direction A is press-fitted into the support hole 46d, and the other end protrudes from the support hole 46d. Also in this embodiment, the linear motion bearing 44a is filled with a solid lubricant.

  One end portion of each shaft member 44b in the reference direction A is fixed to the flange portion 49b of the case 49 by a bolt 48. In the present embodiment, each shaft member 44b is fixed to the first fixing portion 80 via the flange portion 49b. In the present embodiment, each shaft member 44b extends in the reference direction A from the first fixed portion 80 side toward the second extending portion 46b side. The other end side in the reference direction A of each shaft member 44b is inserted into the linear motion bearing 44a. That is, also in the present embodiment, the linear motion bearing 44a supports the shaft member 44b so as to cover the outer peripheral surface on the other end side of the shaft member 44b. Specifically, the linear motion bearing 44a does not restrict the movement of the shaft member 44b in the reference direction A, moves in the shear direction B, and a direction orthogonal to the reference direction A and the shear direction B (this embodiment). In the embodiment, the shaft member 44b is supported so as to restrict movement in the vertical direction). The shaft member 44b may be indirectly fixed to the first fixing portion 80 via the flange portion 49b as described above, and is directly fixed to the first fixing portion 80 as in the holding device 10 of FIG. May be.

  The case 49 is fixed to the first fixing portion 80 by a bolt (not shown). In the present embodiment, for example, the flange portion 49 b is fixed to the first fixing portion 80. The case 49 is connected to the second extending portion 46b by a plurality of linear motion bearings 44a and a plurality of shaft members 44b. Therefore, the case 49 is not displaced with respect to the second extending portion 46b in the shear direction B and the vertical direction. As a result, even when a stress in the shear direction B is applied to the test piece 60 (test unit 61), no bending load is generated in the first load cell 47 accommodated in the recess 46c and the recess 49c, and the first load cell 47 Durability can be improved.

  The second arm 56 extends in the reference direction A of the test unit 61, and one side in the reference direction A is connected to the second driving unit 50, and the other of the first extending part 56a in the reference direction A And a second extending portion 56b that is connected to the side and extends in the shear direction B. The first extending portion 56a and the second extending portion 56b are integrally formed. A second fixing portion 90 is fixed to one end side of the second extending portion 56b in the reference direction A.

  The first fixed portion 80 of the first moving body 16 and the second fixed portion 90 of the second moving body 17 are relatively displaced in the reference direction A by the first driving portion 40 and are sheared by the second driving portion 50. It is displaced relative to B.

  Next, the structure of the 1st fixing | fixed part 80 of the 1st moving body 16 is demonstrated using FIG. 2 and FIG. 4 to FIG. FIG. 4 is a perspective view of a first fixing portion of the holding device shown in FIG. FIG. 5 is a plan view of the first base member. 6 is a cross-sectional view taken along line VI-VI in FIG. In the following description, the longitudinal direction of the test piece 60 (arrow A direction) and the shear direction of the test piece 60 (arrow B) are based on the state in which the test piece 60 is held by the first fixing part 80 and the second fixing part 90. Each component of the first fixing unit 80 will be described with reference to (direction).

  The first fixing portion 80 includes a first base member 25, a first insertion member 27, and a pair of first slide members 28.

  As shown in FIGS. 4 to 6, the first base member 25 has a shape in which a concave portion having a V-shaped cross section is formed on the upper surface of a rectangular parallelepiped member as a whole. Specifically, the first base member 25 includes a substantially rectangular base portion 25a as viewed from above, a pair of plate-like front walls 25c positioned on one end side of the base portion 25a in the longitudinal direction of the test piece 60, and a test. And a plate-like rear wall 25e located on the other end side of the base portion 25a in the longitudinal direction of the piece 60. The base 25a, the front wall 25c, and the rear wall 25e are integrally formed.

  As shown in FIG. 6, the base 25 a has an upper surface 25 b that is recessed in a V shape when viewed from the longitudinal direction of the test piece 60. That is, the base portion 25a has the largest height at both ends in the shear direction of the test piece 60 and the smallest at the center. As a result, a concave portion having a V-shaped cross section is formed on the upper surface 25b of the first base member 25 as described above. A pair of first slide members 28 is placed on the upper surface 25b of the base portion 25a. The inclination angle of the upper surface 25b of the base portion 25a with respect to the horizontal plane can be 45 °, for example. In order to allow the pair of first slide members 28 to move in the shear direction of the test piece 60 on the upper surface 25b, the inclination angle is set to less than 90 °. The inclination angle is preferably as small as possible.

  A gap 25d extending in the vertical direction is provided between the pair of front walls 25c. In the pair of front walls 25c, a pair of fixing portions 22 are formed at end portions located on the gap 25d side. A pair of fixing | fixed part 22 is formed by notching the base part 25a side of the said edge part in a pair of front wall 25c. The pair of fixing parts 22 are positioned so as to sandwich the test piece 60 positioned in the gap 25d in the shearing direction in a state where the test piece 60 is disposed in the first fixing part 80 as shown in FIG. 2B. . Specifically, the pair of fixing portions 22 are positioned so as to contact the fixing portion 23 and the holding portion 62 in a state where the test piece 60 is arranged in the first fixing portion 80 as shown in FIG. It is done. A stage 29 is disposed in a gap 25d located between the pair of front walls 25c. The stage 29 will be described later.

  A gap 25f is formed in the rear wall 25e at the center of the test piece 60 in the shearing direction. Specifically, the gap 25f is formed to extend from the upper end of the rear wall 25e to a substantially central portion in the vertical direction of the rear wall 25e. The fixing portion 21 described below is inserted into the gap 25f.

  The first insertion member 27 is a member having a T shape as viewed from above. The first insertion member 27 includes a plate-like stable portion 27a extending in the shear direction of the test piece 60, and a fixing portion 21 extending in the longitudinal direction of the test piece 60 from the longitudinal center portion of the stable portion 27a. The fixing portion 21 is inserted into a gap 25f provided in the rear wall 25e. Thereby, the fixing | fixed part 21 is positioned so that it may contact the edge part of the longitudinal direction of the test piece 60 in the state which has arrange | positioned the test piece 60 in the 1st fixing | fixed part 80 as shown in FIG.2 (b). The stable portion 27a is fixed to the rear wall 25e by a bolt (not shown). Thereby, the fixing | fixed part 21 is also fixed to the position which contacts the edge part of the longitudinal direction of the test piece 60. FIG.

  Therefore, in the first fixing portion 80 of the present embodiment, the fixing portion 21 can be fixed at a position in contact with the end portion in the longitudinal direction of the test piece 60 according to the size of the test piece 60. In the present embodiment, the holding portion 62 of the test piece 60 can be held from both sides in the longitudinal direction of the test piece 60 by the fixing portion 21 and the pair of fixing portions 22 without being deformed. Moreover, the configuration in which the fixing portion 21 is inserted into the gap 25f provided in the rear wall 25e as described above allows the test piece 60 to be formed by the fixing portion 21 and the pair of fixing portions 22 regardless of the size of the test piece 60. The holding part 62 can be held.

  The pair of first slide members 28 is a prismatic member having a trapezoidal cross section perpendicular to the axis and extending along the axis. Each of the pair of first slide members 28 has a fixing portion 23 that protrudes in the axial direction on one of the end faces in the axial direction. The pair of first slide members 28 are placed on the upper surface 25 b of the base portion 25 a so that the axial direction is the longitudinal direction of the test piece 60. Thereby, as for a pair of 1st slide member 28, the movement in the longitudinal direction of the test piece 60 is controlled by the front wall 25c and the rear wall 25e. In the pair of first slide members 28, the movement of the test piece 60 in the shearing direction is restricted when the fixing portion 23 is positioned in the fixing portion 22 of the front wall 25 c. The pair of first slide members 28 has the test piece 60 disposed in the first fixing portion 80 as shown in FIG. 2B, and the fixing portion 23 holds the holding portion 62 of the test piece 60 of the test piece 60. While being sandwiched from both sides in the shearing direction, the fixing portion 23 is disposed so as to be in contact with the fixing portion 22. The pair of first slide members 28 are respectively fixed to the base portion 25 a of the first base member 25 by bolts 24.

  Therefore, in the first fixing portion 80 of the present embodiment, the fixing portion 23 is in a position where it contacts the holding portion 62 of the test piece 60 from both sides in the shear direction of the test piece 60 according to the size of the test piece 60. Can be fixed. That is, the pair of fixing portions 22 can hold the test piece 60 from both sides in the shear direction without deforming the holding portion 62 of the test piece 60.

  The second fixing unit 90 also has the same configuration as the first fixing unit 80. Specifically, the second fixing portion 90 includes a fixing portion 31, a pair of fixing portions 32, a pair of fixing portions 33, a bolt 34, a second base member 35, a base portion 35a, a base upper surface 35b, a front wall 35c, and a front wall. 35d, a rear wall 35e, a rear wall gap 35f, a second insertion member 37, a stabilizing portion 37a, and a second slide member 38. These members of the second fixing portion 90 include the fixing portion 21, the fixing portion 22, the fixing portion 23, the bolt 24, the first base member 25, the base portion 25a, the base upper surface 25b, and the front wall 25c of the first fixing portion 80, respectively. The front wall gap 25d, the rear wall 25e, the rear wall gap 25f, the first insertion member 27, the stabilizing portion 27a, and the first slide member 28 have the same configuration. Note that the second base member 35 may be formed integrally with the second arm 56.

  As described above, the stage 29 is disposed in the gap 25d between the pair of front walls 25c. The stage 29 is disposed so as to be positioned also in the gap 35d between the pair of front walls 35c. That is, the stage 29 is positioned in the gap 25d and the gap 35d. A test piece 60 is placed on the stage 29.

  As described above, the first insertion member 27 and the pair of first slide members 28 are movable with respect to the first base member 25. The first insertion member 27 is fixed to the first base member 25 by bolts (not shown), and the pair of first slide members 28 are fixed to the first base member 25 by bolts 24. The second insertion member 37 and the pair of second slide members 38 are movable with respect to the second base member 35. The second insertion member 37 is fixed to the second base member 35 by bolts (not shown), and the pair of second slide members 38 are fixed to the second base member 35 by bolts 34. For this reason, the fixing part 21, the pair of fixing parts 22 and the pair of fixing parts 23 are fixed at positions where they contact the holding part 62 of the test piece 60, and the fixing part 31, the pair of fixing parts 32 and the pair of fixing parts 33 are fixed. The test piece 60 can be fixed at a position in contact with the holding portion 63. Therefore, it is possible to hold a small test piece having a side length of several millimeters without deforming the holding portion. As an example of a test piece having a size applicable to the holding device shown in FIG. 2, a test piece having a shape shown in FIG. 7 to be described later has a length in the longitudinal direction of 3 mm, a width in the shear direction of the test piece of 2 mm, and a thickness. The thing which set the thickness to 0.3 mm is mentioned.

3. Test Method Using Test Specimen Holding Device As shown in FIG. 2, the first fixing unit 80 is configured such that one of the pair of holding units 62 and 63 of the test piece 60 is moved in the longitudinal direction of the test piece 60. The test piece 60 is held from both sides in the shear direction, that is, from four directions. Similarly, the second fixing portion 90 holds the other holding portion 63 from four directions. As described above, the holding device 15 holds the holding parts 62 and 63 from the four directions by the first fixing part 80 and the second fixing part 90. Therefore, in a state where the test piece 60 is held using the holding device 15, the first driving unit 40 tests the first fixing unit 80 of the first moving body 16 and the second fixing unit 90 of the second moving body 17. By relatively displacing in the longitudinal direction (reference direction A) of the piece 60, tensile stress or compressive stress can be applied to the test portion 61 of the test piece 60. In the test piece holding device 15 according to the present embodiment, since the shearing stress and the tensile stress or the compressive stress can be applied in a state where the test portion 61 of the test piece 60 is exposed, the test portion 61 after the stress is applied is provided. It can be easily observed.

  The first fixing part 80 and the second fixing part 90 are relatively and periodically displaced in the longitudinal direction of the test piece 60 (reference direction A of the test part 61), and tensile stress or compressive stress is repeatedly applied to the test part 61. By repeatedly applying as, a fatigue test by tensile / compressive stress can be performed. An example of the repeated stress applied in the fatigue test is a double-swing stress. The swing stress is a stress that alternately changes between a positive maximum value and a negative minimum value, which have the same absolute value, when the tensile stress is positive and the compressive stress is negative. A value obtained by dividing the minimum value of the stress by the maximum value of the stress is referred to as a minimum / maximum stress ratio R, and R = −1 in the double swing stress. The repeated stress applied in the fatigue test is not limited to the double swing stress, but may be a partial swing stress, a single swing stress, a partial single swing stress, or the like.

  Further, the second driving unit 50 relatively displaces the second fixing unit 90 of the second moving body 17 and the first fixing unit 80 of the first moving body 16 in the shearing direction B orthogonal to the reference direction A. The shear stress can be applied to the test part 61. The holding device 15 holds the holding portions 62 and 63 from four directions by the first moving body 16 and the second moving body 17, and therefore rotates the holding portions 62 and 63 when applying shear stress to the test portion 61. It can be moved without Therefore, the deformation of the test unit 61 does not include a bending component, a tensile component, or the like, and it is possible to evaluate the shear characteristics with high accuracy.

  By periodically displacing the first fixing portion 80 and the second fixing portion 90 in the shear direction B and applying the shear stress to the test portion 61 as a repeated stress, a fatigue test using the shear stress can be performed. The repeated stress of the shear stress is also classified into a double swing stress, a partial swing stress, a single swing stress, and a partial single swing stress according to the change in the stress. The definition of the cyclic stress when the one direction of the shear stress is positive and the opposite direction of the one direction is negative is the same as the case of the tensile / compressive stress.

  Further, the first fixing portion 80 and the second fixing portion 90 are relatively displaced in the longitudinal direction of the test piece 60 (reference direction A of the test portion 61), and tensile stress or compressive stress is applied to the test portion 61. By displacing the first fixing part 80 and the second fixing part 90 in the shearing direction B perpendicular to the reference direction A, a shear stress can be applied to the test part 61. Thus, the test which simulated the load form in an actual structure can be performed by giving a shear stress, giving a tensile stress or a compressive stress.

  In addition, the first fixing part 80 and the second fixing part 90 are relatively displaced in the longitudinal direction of the test piece 60 and tensile stress or compressive stress is applied to the test part 61. By cyclically displacing the second fixing portion 90 in the shear direction B, a shear stress can be applied to the test portion 61 as a repeated stress. Furthermore, by displacing the first fixing part 80 and the second fixing part 90 relatively and periodically in the longitudinal direction (reference direction A) of the test piece 60 and also periodically in the shear direction B, It is also possible to apply tensile / compressive stress and shear stress to the test portion 61 as repeated stress. Therefore, by using the holding device 15 described above, a fatigue test simulating a load form to which various repeated stresses are applied can be performed.

  In the holding device 15, a cylindrical linear motion bearing 44 a is provided in the support hole 46 d of the first arm 46 so as to extend in the reference direction A. The linear motion bearing 44 a supports the shaft member 44 b so as to cover the outer peripheral surface of the shaft member 44 b fixed to the first fixing portion 80. More specifically, in the present embodiment, one end side of the shaft member 44b is fixed to the first fixing portion 80 via the case 49, and the outer peripheral surface of the other end side of the shaft member 44b is covered by the linear motion bearing 44a. Yes. With such a configuration, the linear motion bearing 44a supports the shaft member 44b so as not to restrict the movement of the shaft member 44b in the reference direction A but to restrict the movement in the shear direction B and the movement in the vertical direction. can do. Accordingly, it is possible to prevent the shaft member 44b fixed to the first fixing portion 80 from moving in a direction other than the reference direction A with respect to the second extending portion 46b of the first arm 46. Therefore, for example, when the first arm 46 and the second arm 56 are reciprocated relatively in the shear direction B to apply a shear load to the test portion 61, the first fixing portion 80 is moved relative to the second extending portion 46b. Thus, relative movement in directions other than the reference direction A can be prevented. Therefore, when the load in the shear direction B is transmitted between the second extending portion 46b and the first fixing portion 80 via the connection portion 45, vibration is generated in the first arm 46 and the first fixing portion 80. Can be prevented. As a result, the shear load waveform actually applied to the test unit 61 is prevented from being disturbed with respect to the shear load input waveform (the load waveform input to the first arm 46 or the second arm 56). it can. Thereby, a desired shear stress can be generated in the test part 61, and an appropriate test can be performed.

  Further, in the holding device 15, the reference direction of the first fixed portion 80 with respect to the second extending portion 46b by the linear motion bearing 44a and the shaft member 44b provided on one side and the other side of the first load cell 42 in the shear direction B, respectively. Movement in directions other than A is restricted. Thereby, when giving a shear load to the test part 61, it can fully suppress that the 2nd extending | stretching part 46b and the 1st fixing | fixed part 80 displace relatively to directions other than the reference direction A. FIG. Therefore, it is possible to sufficiently suppress the load in the shear direction B from being applied to the first load cell 42. Further, as described above, the linear motion bearing 44a does not regulate the movement of the shaft member 44b in the reference direction A. Thereby, when a tensile load or a compressive load is applied to the test portion 61, it is possible to prevent a load in the reference direction A from being applied to the shaft member 44b. As a result, the load in the reference direction A applied to the test unit 61 can be detected with high accuracy by the first load cell 42.

  In the holding device 15, the linear motion bearing 44a is filled with a solid lubricant. In this case, when a load in the shear direction is transmitted from the second extending portion 46b to the first fixing portion 80 via the connection portion 45, vibration is generated in the second extending portion 46b and the first fixing portion 80. It can be sufficiently prevented. As a result, the occurrence of disturbance in the shear load applied to the test unit 61 can be sufficiently suppressed.

4). FIG. 7 is a plan view of a test piece suitable for the test method according to the embodiment of the present invention. As described with reference to FIG. 1B, the test piece 60 shown in FIG. 7 is arranged between a pair of holding portions 62 and 63 arranged at both ends in the longitudinal direction and the holding portions 62 and 63. And a test unit 61.

  Furthermore, as shown in FIG. 7, the test unit 61 has R portions 61 a at both ends connected to the holding units 62 and 63. In the test part 61, an arc part 61 b is formed at the center part in the longitudinal direction of the test piece 60. The arc portion 61 b is formed such that the width dimension of the test portion 61 is smallest at the center portion in the longitudinal direction of the test piece 60. The radius of curvature of the arc portion 61b is larger than the radius of curvature of the R portion 61a.

  In the test method according to the embodiment of the present invention, as described above, it is preferable to use a test piece having a shape in which the test portion 61 includes the R portion 61a and the arc portion 61b. The reason is as follows. When stress is applied to the test piece 60 by the R portion 61a, stress concentration at the connection portion between the test portion 61 and the holding portions 62 and 63 can be suppressed, and the failure of the test piece to break at this connection portion can be prevented. Can be reduced. When stress is applied to the test piece 60 by the arc portion 61b, the possibility of deformation due to yielding occurring in the central portion in the longitudinal direction of the test piece 60 of the test portion 61 becomes very high, and the same position for a plurality of test pieces Can be used to evaluate deformation. Therefore, it is possible to perform highly accurate evaluation with a high yield.

  FIG. 8 is a configuration diagram of a test piece more suitable for a fatigue test among the test methods according to the embodiment of the present invention. FIG. 8 (a) shows a plan view and FIG. 8 (b) shows a side view. . A test piece 70 shown in FIG. 8 has a pair of holding portions 72 and 73 located at both ends in the longitudinal direction, and a test portion 71 provided between the holding portions 72 and 73. The holding parts 72 and 73 protrude in the shearing direction of the test piece 70.

  Furthermore, as shown in FIG. 8, the test unit 71 has R portions 71a at both ends connected to the holding portions 72 and 73, and has parallel portions 71c having a uniform width W between the R portions 71a. The parallel portion 71 c is formed with a notch 71 b in the center portion in the longitudinal direction of the test piece 70. The notch 71b is provided so as to extend in the shearing direction of the test piece 70, and its cross section has an arc shape. Therefore, the thickness dimension of the test part 71 is the smallest at the center part in the longitudinal direction of the test piece 70, that is, the bottom part of the notch 71b. The other surface in the thickness direction of the test piece 70 is flat. Further, the thickness t of the test piece 70 at the bottom of the notch 71b is ½ or less of the maximum thickness dimension h of the test portion 71, and the radius of curvature of the arc constituting the cross section of the notch 71b is the radius of curvature of the R portion 71a. Therefore, when tensile stress, compressive stress, or shear stress is applied to the test piece 70, the bottom of the notch 71b becomes a stress concentration portion. As described above, when a shear fatigue test is performed using the test piece 70, a fatigue crack is generated at the bottom of the notch 71b. Therefore, the fatigue crack can be evaluated at the same position for a plurality of test pieces. Therefore, evaluation can be performed with a high yield.

The cross-sectional area (W × t) at the bottom of the notch 71b of the test piece 70 is preferably 0.05 mm ² or more. By setting the cross-sectional area at the bottom of the notch 71b to 0.05 mm ² or more, a sufficiently large stress can be applied during the fatigue test, and highly accurate measurement can be performed. The cross-sectional area at the bottom of the notch 71b is more preferably 0.075 mm ² or more.

  In the parallel part 71c, it is preferable that the relationship between the width W and the length L in the longitudinal direction of the test piece 70 satisfies W> L. In this case, since the shear stress acts larger than the bending stress during the shear fatigue test, the central portion in the width direction of the bottom of the notch 71b becomes the stress concentration portion. Since the fatigue crack is generated at this stress concentration portion, it is possible to perform evaluation with higher yield. The reason why W> L is preferable will be described below.

When the shearing force P in the shear direction of the test piece 70 is applied to the holding portion 73 of the test piece 70, the maximum shear stress τ _max generated in the cross section including the bottom of the notch 71b is expressed by the following equation (i).
τ _max = (3/2) × (P / tW) (i)
Further, in this case, the maximum value σ _{max of the} stress generated on the boundary surface between the R portion 71a and the parallel portion 71c on the holding portion 73 side is set to L in the longitudinal direction of the test piece 70 of the parallel portion 71c. Assuming the bending stress of the surface, it is expressed by the following equation (ii).
^{_{σ max ≒ (PL × W /}} 2) / (hW 3/12) = 6PL / hW 2 ... (ii)

Here, assuming that the fracture law of the test piece 70 follows the misses stress, when the following equation (iii) holds, the misses stress in the cross section including the bottom of the notch 71b is the R portion 71a on the holding portion 73 side and the parallel portion 71c. It becomes more than the misses stress at the boundary surface. That is, the shear stress acts more than the bending stress. In this case, the test piece 70 is broken at the bottom of the notch 71b.
τ _max ≧ σ _max / 3 ^1/2 (iii)

Here, as described above, the thickness t of the test piece 70 at the bottom of the notch 71b is equal to or less than ½ of the maximum thickness dimension h of the test piece 70, that is, h / 2 ≧ t. The following formula (iv) is obtained from h / 2 ≧ t and the formulas (i) to (iii), and the formula (v) is further obtained from the formula (iv). From the equation (v), it is understood that W> L is preferable.
h / 2 ≧ (3 ^1/2 / 2) × (hW / L) ≧ t (iv)
W / L ≧ 2/3 ^1/2 ≈1 (v)

  FIG. 9 is a diagram showing the result of analyzing the test piece 70 by the finite element method (FEM) in terms of stress distribution. As a result of the analysis by FEM, in the test piece 70, the stress is concentrated at the bottom of the notch 71b in both cases where the shear stress is applied and the tensile / compressive stress is applied as shown in FIG. Was confirmed to occur. When shear stress is applied, maximum stress is generated particularly at the center in the width direction of the bottom of the notch 71b. The notch 71b may be provided on only one of the surfaces in the thickness direction of the test piece 70, or may be provided on both.

  It is preferable that both the test piece 60 and the test piece 70 are pickled and then used for the test. This is for removing a surface layer such as an electric discharge machining layer or a residual stress layer formed on the surface when a test piece is produced by electric discharge machining, for example.

  In order to confirm the effect of the above-described configuration, a shear test of Examples and Comparative Examples was performed. The shear test of the example was performed using the holding device 15 shown in FIG. The shear test of the comparative example was performed using the holding device 100 shown in FIG.

  10 is different from the holding device 15 in FIG. 2 in that the first arm 101 is provided instead of the first arm 46, and the case 102 is provided instead of the case 49. The point is that the linear motion bearing 44a and the shaft member 44b are not provided. The first arm 101 is provided so as to cover both side surfaces 102 a and 102 b in the shear direction B of the case 102 and one side surface 102 c in the reference direction A. The case 102 is fixed to the first fixing portion 80. In the holding device 100, both side surfaces 102 a and 102 b of the case 102 are fixed to the first arm 101 in order to accurately detect the load in the reference direction A acting on the test portion 61 of the test piece 60 by the first load cell 47. I can't do it. Therefore, a slight gap is formed between the side surfaces 102 a and 102 b and the first arm 101.

  In both the example and the comparative example, the load in the shear direction B that periodically changes was applied to the second arm 56, and the load in the shear direction B acting on the test piece 60 was detected by the second load cell 43. FIG. 11 is a graph showing the waveform of the load input to the second arm 56 and the waveform of the load detected by the second load cell 43 in the shear test of the example. FIG. 12 shows the shear of the example. 4 is a graph showing a waveform of a load input to a second arm 56 and a waveform of a load detected by a second load cell 43 in a test.

  As can be seen from FIG. 11, in the shear test of the embodiment using the holding device 15, the waveform of the load detected by the second load cell 43 is almost distorted with respect to the waveform of the load input to the second arm 56. There wasn't. From this, it is considered that the desired shear stress could be generated in the test part 61 of the test piece 60 in the shear test of the example.

  On the other hand, as can be seen from FIG. 12, in the shear test of the comparative example using the holding device 100, the load waveform detected by the second load cell 43 is disturbed with respect to the load waveform input to the second arm 56. It was. From this, it is considered that in the shear test of the comparative example, the waveform of the shear stress generated in the test portion 61 of the test piece 60 was also disturbed. That is, it is considered that a desired shear stress could not be generated in the test part 61.

  In the holding device 100, as described above, it is necessary to form a gap between the side surfaces 102a and 102b of the case 102 and the first arm 101. For this reason, when the second arm 56 periodically moves in the shear direction B, the first arm 101 and the both side surfaces 102a and 102b of the case 102 repeat contact and separation, whereby the first arm 101 and the first arm It is considered that vibration occurred in the fixed portion 80. For this reason, as described above, it is considered that the waveform of the load detected by the second load cell 43 is disturbed.

  The test piece holding apparatus according to the present invention can be applied to a test apparatus capable of applying tensile stress or compressive stress while applying shear stress without causing deformation of a small test piece.

10, 15 Holding device 20 First fixing part 30 Second fixing part 40 First driving part (stretching direction driving part)
50 Second drive unit (shear direction drive unit)
60, 70 Test piece 61, 71 Test part 61a, 71a R part 61b Arc part 71b Notch 71c Parallel part 62, 72 One holding part 63, 73 The other holding part 80 First fixing part 90 Second fixing part A Test part Stretching direction (longitudinal direction of test piece)
B Direction perpendicular to the stretching direction of the test section (shear direction of the test piece)
C Connection part of holding part with test part

Claims (5)

A test part extending in one direction, and a pair of holding parts respectively provided at both ends in the extending direction of the test part so as to protrude in the shear direction perpendicular to the extending direction of the test part with respect to the test part An apparatus for holding a test piece having
A first fixing portion that holds one of the pair of holding portions;
A first arm movably provided in the shear direction;
A connecting portion for connecting the first fixed portion and the first arm;
A second fixing portion that holds the other of the pair of holding portions;
A second arm provided integrally with the second fixing portion so as to be movable in the extending direction;
The first fixing part is
A first stretching direction fixing portion that holds the one holding portion from both sides in the stretching direction;
A first shearing direction fixing part that holds the one holding part from both sides in the shearing direction;
The second fixing part is
A second stretching direction fixing portion that holds the other holding portion from both sides in the stretching direction;
A second shearing direction fixing part that holds the other holding part from both sides in the shearing direction;
The first arm has a support portion provided on the opposite side of the second fixing portion when viewed from the first fixing portion in the extending direction;
The support part has a support hole formed so as to open toward the first fixed part and extend in the extending direction;
The connecting portion is provided in the support hole so as to be fixed to the first fixing portion and extending in the extending direction from the first fixing portion side toward the supporting portion side, and in the extending direction. A cylindrical linear motion bearing,
The test piece holding device, wherein the shaft member is inserted into the linear motion bearing such that an outer peripheral surface thereof is covered with the linear motion bearing. The specimen holding device according to claim 1,
The connection portion further includes a load cell that is provided between the support portion and the first fixing portion and detects a load acting on the support portion and the first fixing portion in the extending direction,
The support part has at least two support holes respectively formed on one side and the other side of the load cell in the shear direction;
The connection portion includes at least two linear motion bearings and at least two shaft members;
A holding device for a test piece, wherein the linear motion bearing is provided in each support hole, and the shaft member is inserted into the linear motion bearing. The holding device according to claim 1 or 2,
A test piece holding device in which the linear motion bearing is filled with a solid lubricant. The specimen holding device according to any one of claims 1 to 3,
The first stretching direction fixing portion and the second stretching direction fixing portion are respectively opposite to the compression direction fixing portion in contact with the end of the test piece in the stretching direction and the compression direction fixing portion in the stretching direction. A test piece holding device having a tensile direction fixing portion that comes into contact with the holding portion from the side. In the holding device of the test piece according to any one of claims 1 to 4,
At least one of the first fixing part and the second fixing part is connected to an extension direction driving part that relatively displaces the first fixing part and the second fixing part in the extension direction;
At least one of the first fixing part and the second fixing part is connected to a shear direction driving part that relatively displaces the first fixing part and the second fixing part in the shear direction. Holding device.