Fatigue testing fixture, fatigue testing apparatus, and fatigue testing method

Abstract

This paper proposes a fatigue testing jig, fatigue testing apparatus, and fatigue testing method that suppress axial displacement during loading tests and enable efficient fatigue testing of concrete. [Solution] A fatigue test jig 13 having an upper plate 2, a lower plate 3 facing the upper plate 2 with the test specimen S in between, and a plurality of leg members 4, 4 interposed between the upper plate 2 and the lower plate 3 around the test specimen S, wherein at least one of the upper plate 2 and the lower plate 3 is provided with a shear stopper 23, 31 for holding the test specimen S.

Description

Technical Field

[0001] The present invention relates to a fatigue test jig, a fatigue test apparatus, and a fatigue test method.

Background Art

[0002] For the purpose of reducing the emission amount of greenhouse gases, the demand for renewable energy is increasing. Examples of renewable energy include solar power generation, wind power generation, hydroelectric power generation, geothermal power generation, biomass, etc. Wind power generation facilities may affect the living environment due to noise and vibration from wind turbines, and it is necessary to fully consider the impact on living spaces, etc., so they are often installed in mountainous areas far from residential areas. However, it is difficult to secure land for installing large wind turbines in mountainous areas, and it is also difficult to secure transportation routes to the wind power generation facilities and install transmission lines, etc. Therefore, it has been considered to install wind power generation facilities on the sea (water).

[0003] When constructing a structure on water, a floating structure may be adopted as the foundation structure. Examples of floating foundation structures include semi-submersible type, spar type, perge type, TLP type, etc. Among these, the semi-submersible type foundation (semi-submersible floating foundation) includes a center column, a plurality of side columns arranged at intervals around the center column, and beams (pontoons) connecting the center column and the side columns, and has excellent stability performance against waves and wind, so there are relatively many actual achievements. Floating foundations are often mainly composed of steel members. On the other hand, if all or part of the floating foundation is constructed of concrete, cost reduction can be achieved.

[0004] Furthermore, the floating foundations of offshore wind power generation facilities are constantly subjected to wave forces and forces from the wind turbines. For example, assuming a service life of 25 years and a wave period of 10 seconds, the floating foundation will be subjected to wave forces approximately 80 million times (25 years × 365 days × 24 hours × 3600 seconds ÷ 10 seconds) over 25 years. Therefore, when adopting a floating foundation made of concrete, it is necessary to consider the fatigue of the concrete. On the other hand, there are many unknowns regarding the fatigue life of concrete under low stress. Therefore, in order to confirm the fatigue life of concrete under low stress, loading tests (fatigue tests) are necessary, but loading tests involving tens of millions of cycles will require a long test period even if conducted at loading speeds of a few Hz to 10 Hz. Therefore, conducting multiple test cases will require a considerable amount of time.

[0005] Patent Document 1 discloses a fatigue testing jig for efficiently performing fatigue tests on multiple test cases, comprising a columnar base having two opposing planes, an internal space, and an opening on one of the planes; a spherical seat positioned on the surface opposite the opening in the internal space; and a pressure plate rotatably held within the internal space by the spherical seat. The fatigue testing jig of Patent Document 1 makes it possible to perform tests on multiple test cases simultaneously by stacking them vertically with the test specimens placed in the internal space. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-055515 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The fatigue testing fixture described in Patent Document 1 has a structure with a spherical base, which may cause instability due to the shifting of the central axis between the base or pressure plate and the test specimen caused by vibrations from repeated loading. Furthermore, the base may tilt when the test specimen is destroyed. When multiple fatigue test fixtures are stacked and multiple test cases are performed, if the base of one fatigue test fixture tilts, the central axis of the other fatigue test fixtures may shift.

[0008] The present invention aims to propose a fatigue testing jig, fatigue testing apparatus, and fatigue testing method that suppress the deviation of the central axis during loading tests and enable efficient fatigue testing of concrete. [Means for solving the problem]

[0009] The first fatigue testing fixture of the present invention, which solves the aforementioned problems, has an upper plate and a lower plate that faces the upper plate with the test specimen in between, and a shear stopper for holding the test specimen is provided on at least one of the upper plate and the lower plate. With this fatigue testing fixture, displacement of the central axis is suppressed when loading is performed or when the test specimen is set up.

[0010] The second fatigue test fixture comprises an upper plate, a lower plate facing the upper plate with the test specimen in between, and a plurality of leg members interposed between the upper and lower plates around the test specimen. The leg members consist of an upper leg member fixed to the lower surface of the upper plate and a lower leg member fixed to the upper surface of the lower plate. A recess is formed at one end of the upper leg member and the lower leg member, and a protrusion is formed at the other end of the upper leg member and the lower leg member that can be fitted into the recess. Furthermore, the leg members are arranged such that a part of the protrusion is inserted into the recess, and there is a gap between the tip surface of the protrusion and the bottom surface of the recess. With this fatigue test fixture, because the leg members are arranged between the upper and lower plates, tilting of the upper and lower plates due to vibration from repeated loading is suppressed, and consequently, displacement of the central axis during loading is suppressed.

[0011] Furthermore, if a pressure plate is formed on the lower surface of the upper plate that contacts the upper surface of the test specimen, sufficient load-bearing capacity can be ensured in the necessary parts, which is less expensive than increasing the load-bearing capacity of the entire upper plate.

[0012] Furthermore, if a water tank surrounding the test specimen is formed between the upper and lower plates, testing simulating underwater conditions can also be performed. In this case, the height of the water tank should be greater than the height of the test specimen.

[0013] The first fatigue testing apparatus of the present invention comprises a base, a loading means disposed above the base, and the fatigue testing fixtures stacked vertically in multiple stages between the base and the loading means. With such a fatigue testing apparatus, since multiple fatigue testing fixtures are stacked, long-term fatigue testing can be efficiently performed on multiple test cases.

[0014] Furthermore, if multiple laser displacement meters for measuring the displacement of each upper plate are provided on the lower plate of the fatigue test fixture located at the lowest level, it is desirable that through holes be formed in the upper and lower plates, which are positioned between the laser displacement meters and the upper plate being measured by the laser displacement meters, corresponding to the irradiation direction of the laser displacement meters. In this way, the displacement history of fatigue tests for multiple test cases can be measured over a long period of time.

[0015] The second fatigue testing apparatus comprises a base, a loading means disposed above the base, a plurality of plate materials disposed above and below the test specimen between the base and the loading means, and a plurality of leg materials interposed between the plate materials around the test specimen. At least one of the upper and lower surfaces of the plate material is provided with a slip-prevention device to hold the test specimen. The leg materials consist of an upper leg member and a lower leg member disposed above and below each other, with a recess formed at one end of the upper leg member and the lower leg member, and a protrusion formed at the other end of the upper leg member and the lower leg member that can be fitted into the recess. The leg materials are disposed such that a part of the protrusion is inserted into the recess, and there is a gap between the tip surface of the protrusion and the bottom surface of the recess. With such a fatigue testing apparatus, when fatigue testing is performed on multiple test specimens simultaneously, only one plate material is interposed between the test specimens, making it more economical than when there are upper and lower plates.

[0016] The fatigue test method of the present invention includes a specimen installation step of setting a columnar specimen between the upper plate and the lower plate, a jig installation step of stacking a plurality of the fatigue test jigs with the specimen set between the pedestal and the loading means, and a loading step of repeatedly applying a load by the loading means. When the fatigue test jig used in the fatigue test has a water tank, a water injection step of pouring water into the water tank is performed before the loading step.

Advantages of the Invention

[0017] According to the fatigue test jig, fatigue test apparatus, and fatigue test method of the present invention, it is possible to suppress the deviation of the central axis in the loading test and efficiently perform the fatigue test of concrete.

Brief Description of the Drawings

[0018] [Figure 1] It is a front sectional view showing the fatigue test apparatus of the first embodiment. [Figure 2] It is a sectional view looking up at the upper plate from below. [Figure 3] It is a sectional view looking down at the lower plate from above. [Figure 4] It is a sectional view looking up at the lowermost lower plate from above. [Figure 5] It is an enlarged sectional view showing a part of the leg member. [Figure 6] It is a flowchart showing the fatigue test method of the first embodiment. [Figure 7A] It is a front sectional view showing the fatigue test apparatus at the time of specimen fracture. [Figure 7B] It is a partially enlarged sectional view showing a part of the leg member of the fatigue test apparatus at the time of specimen fracture. [Figure 8] It is a front sectional view showing the fatigue test apparatus of the second embodiment. [Figure 9] It is a flowchart showing the fatigue test method of the second embodiment.

Modes for Carrying Out the Invention

[0019] <First Embodiment> In the first embodiment, a submersible compression fatigue test of concrete will be described. In a submersible compression fatigue test, a concrete specimen S is submerged in water and subjected to repeated loads to measure the strength and yield strength of the specimen S. The specimen S is cylindrical in shape. In this embodiment, a submersible compression fatigue test is performed simultaneously on multiple (three in this embodiment) specimens S, S, S using a fatigue testing apparatus 1. Figure 1 shows the fatigue testing apparatus 1.

[0020] As shown in Figure 1, the fatigue testing apparatus 1 comprises a base 11, a loading means 12 positioned above the base 11, and fatigue testing fixtures 13, 13, 13 stacked vertically in multiple layers (three layers in this embodiment) between the base 11 and the loading means 12. The fatigue testing apparatus 1 is a device that performs a compression fatigue test on a test specimen S by repeatedly applying a load to the fatigue testing fixture 13 on which the test specimen S is placed using the loading means 12.

[0021] The fatigue test fixture 13 comprises an upper plate 2, a lower plate 3, a plurality of (four in this embodiment) leg members 4, 4, ..., and a water tank 5. The lowest fatigue test fixture 13 also comprises a plurality of laser displacement meters 6, 6, ... The fatigue test fixtures 13 are stacked by placing the lower plate 3 on the upper plate 2 of the fatigue test fixture 13 located below. The upper plate 2 and lower plate 3 (fatigue test fixtures 13) stacked vertically may be fixed together with fixing fixtures as needed.

[0022] The upper plate 2 is positioned above the specimen S. Figure 2 shows the upper plate 2. As shown in Figures 1 and 2, the upper plate 2 consists of a main body 21 made of a stainless steel plate that is rectangular in plan view, and a pressure plate 22 formed on the lower surface of the main body 21. The pressure plate 22 is formed on the lower surface of the upper plate 2 at a position that contacts the upper surface of the specimen S. The pressure plate 22 is made of a stainless steel member that is rectangular in plan view and has a planar shape smaller than the planar shape of the main body 21. The pressure plate 22 has a thickness that exhibits sufficient resistance to the compressive force applied by the loading means 12. Note that the shape of the upper plate 2 and the materials that constitute the upper plate 2 are not limited. Also, the main body 21 and the pressure plate 22 do not necessarily have to be rectangular in plan view.

[0023] A shear stopper 23 for holding the test specimen S is provided on the lower surface of the pressure plate 22 (upper plate 2). As shown in Figures 1 and 2, the shear stopper 23 is an annular projection in plan view, formed to abut against the upper end of the side surface of the test specimen S. Note that the shear stopper 23 does not necessarily have to be annular, and may be an intermittently formed projection.

[0024] The lower plate 3 consists of a stainless steel plate with a rectangular shape in plan view, positioned opposite the upper plate 2 with the test specimen S in between. Figure 3 shows the lower plate 3. As shown in Figures 1 and 3, the lower plate 3 in this embodiment has the same planar shape and thickness as the main body portion 21 of the upper plate 2. The shape and dimensions of the lower plate 3 are not limited, and for example, it may be made of a plate that is thinner than the upper plate 2.

[0025] A slip-preventing device 31 is provided on the upper surface of the lower plate 3 to hold the test specimen S. As shown in Figures 1 and 3, the slip-preventing device 31 is an annular projection in plan view, formed to abut against the lower end of the side surface of the test specimen S. Note that the slip-preventing device 31 does not necessarily have to be annular, and may be an intermittently formed projection. Furthermore, the slip-preventing device 31 may be formed only as needed. For example, only one of the slip-preventing devices 23 on the upper plate 2 and the slip-preventing device 31 on the lower plate 3 may be formed.

[0026] As shown in Figure 1, the leg members 4 are interposed between the upper plate 2 and the lower plate 3. In this embodiment, as shown in Figures 2 and 3, the leg members 4 are provided at the four corners of the upper plate 2 and the lower plate 3 so as to surround the specimen S interposed between the upper plate 2 and the lower plate 3. In this embodiment, reinforcing horizontal members 45 are horizontally placed between adjacent leg members 4. The height position and number of horizontal members 45 are not limited. Also, horizontal members 45 may be provided as needed.

[0027] As shown in Figure 1, the leg member 4 consists of an upper leg member 41 fixed to the lower surface of the upper plate 2 and a lower leg member 42 fixed to the upper surface of the lower plate 3. A recess 43 is formed at the upper end of the lower leg member 42, and a protrusion 44 that can be fitted into the recess 43 is formed at the lower end of the upper leg member 41. Figure 5 shows the joint between the upper leg member 41 and the lower leg member 42. As shown in Figure 5, the leg member 4 is arranged such that a part of the protrusion 44 is inserted into the recess 43, and there is a gap between the tip surface of the protrusion 44 and the bottom surface of the recess 43. When the leg member 4 has a gap between the tip surface of the protrusion 44 and the bottom surface of the recess 43, it has a length (height) equal to the height of the specimen S before failure, and when the recess 43 and the protrusion 44 are fitted together, it has a length (height) smaller than the height of the specimen S before failure.

[0028] The water tank 5 is provided between the upper plate 2 and the lower plate 3. As shown in Figures 1 and 3, the water tank 5 is provided so as to surround the test specimen S interposed between the upper plate 2 and the lower plate 3. The water tank 5 is made of a transparent material such as acrylic and is configured so that the test specimen S provided inside can be seen. In this embodiment, the water tank 5 has a rectangular shape in plan view, with dimensions larger than the pressure plate 22. The planar shape of the water tank 5 is not limited and may be cylindrical, for example. The upper end of the water tank 5 is located above the lower surface of the pressure plate 22 and below the lower surface of the main body 21. That is, the water tank 5 is greater than the height of the test specimen S and has a height that does not come into contact with the upper plate 2. The distance between the upper end of the water tank 5 and the lower surface of the upper plate 2 is greater than the distance between the tip surface of the convex portion 44 and the bottom surface of the concave portion 43.

[0029] As shown in Figures 1 and 4, multiple laser displacement meters 6, 6, ... are mounted on the lower plate 3 of the fatigue test fixture 13 located at the bottom. Figure 4 is a cross-sectional view showing the lower plate 3 of the bottommost fixture. The laser displacement meter 6 measures the displacement of one of the upper plates 2 of the multiple fatigue test fixtures 13, 13, 13 stacked vertically. As shown in Figure 1, through holes 24 and 32 are formed in the upper plate 2 and lower plate 3, which are positioned between the laser displacement meter 6 and the upper plate 2 that the laser displacement meter 6 is measuring, corresponding to the irradiation direction of the laser beam L of the laser displacement meter 6. For example, the through holes 24 and 32 are formed in a straight line in the upper plate 2 of the bottommost fatigue test fixture 13, the upper plate 2 and lower plate 3 of the middle fatigue test fixture 13, and the lower plate 3 of the topmost fatigue test fixture 13, in accordance with the irradiation direction of the laser beam L of the laser displacement meter 6 that measures the displacement of the upper plate 2 of the topmost fatigue test fixture 13. Furthermore, through holes 24 and 32 are formed in a straight line in the upper plate 2 of the lowest fatigue test fixture 13 and the lower plate 3 of the middle fatigue test fixture 13, aligned with the direction of irradiation of the laser beam L of the laser displacement meter 6 that measures the displacement of the upper plate 2 of the middle fatigue test fixture 13.

[0030] The fatigue testing method using the fatigue testing apparatus 1 of this embodiment will be described below. Figure 6 shows the procedure of the fatigue testing method. As shown in Figure 6, the fatigue testing method of this embodiment comprises a test specimen installation step S11, a jig installation step S12, a water injection step S13, and a loading step S14.

[0031] In the specimen setup process S11, the columnar specimen S is set between the upper plate 2 and lower plate 3 of the fatigue test fixture 13. First, the specimen S is erected inside the slip-prevention stopper 31 of the lower plate 3. Next, the water tank 5 is placed around the specimen S, and the upper plate 2 is set from above the specimen S. At this time, a gap is ensured between the tip surface of the convex portion 44 of the leg member 4 and the bottom surface of the concave portion 43 (see Figure 5).

[0032] In the jig installation process S12, the fatigue test jigs 13, 13, 13, each containing the test specimen S, are stacked on the base 11, and the loading means 12 is set from above (see Figure 1). In the water filling process S13, water is poured into the water tank 5. In the loading process S14, a repeated load is applied to the fatigue test fixture 13 by the loading means 12. Since a gap is provided between the tip surface of the convex portion 44 and the bottom surface of the concave portion 43 of the leg member 4, the repeated load applied in the vertical direction acts on the test specimen S.

[0033] Figures 7A and 7B show the fatigue testing apparatus 1 after the specimen has failed. As shown in Figure 7A, when the specimen S (the lowest specimen S in Figure 7A) fails, the upper plate 2 of the fatigue testing fixture 13 on which the specimen S is set descends. At this time, as shown in Figure 7B, the gap between the tip surface of the convex portion 44 of the leg member 4 and the bottom surface of the concave portion 43 disappears, and the tip surface of the convex portion 44 comes into contact with the bottom surface of the concave portion 43. As a result, the fatigue testing fixture 13 can transmit the load via the leg member 4, and testing with other fatigue testing fixtures 13 can continue.

[0034] According to the fatigue testing apparatus 1 of this embodiment, since fatigue testing fixtures 13, 13, 13 are stacked vertically between the base 11 and the loading means 12, fatigue testing over a long period of time can be efficiently performed on multiple test cases.

[0035] Since the leg members 4 are positioned between the upper plate 2 and the lower plate 3, tilting of the upper plate 2 and the lower plate 3 due to vibrations from repeated loading is suppressed, and consequently, displacement of the central axis during loading is suppressed. Furthermore, if the test specimen S breaks, the leg members 4 allow for force transmission between the upper plate 2 and the lower plate 3, so that testing of the test specimen S using other fatigue testing fixtures 13 can continue.

[0036] Since the upper plate 2 has a pressure plate 22 that contacts the upper surface of the specimen S, it is more economical than increasing the overall thickness of the upper plate 2 to ensure sufficient load-bearing capacity against the load during loading. Furthermore, the anti-slip devices 23 and 31 suppress displacement of the central axis of the test specimen S during loading and installation.

[0037] Since it has a laser displacement meter 6 that measures the displacement of each upper plate 2, it is possible to measure the displacement history of fatigue tests for multiple test cases over a long period of time. Since it is equipped with five tanks, it is possible to conduct tests that simulate underwater conditions.

[0038] <Second Embodiment> In the second embodiment, a concrete underwater compression fatigue test will be described, similar to the first embodiment. The underwater compression fatigue test is performed simultaneously on multiple (three in this embodiment) test specimens S, S, S using the fatigue testing apparatus 10. Figure 8 shows the fatigue testing apparatus 10 of the second embodiment.

[0039] As shown in Figure 8, the fatigue testing apparatus 10 comprises a base 11, a loading means 12 positioned above the base 11, a plurality of plate materials 7, 7, ... positioned vertically between the base 11 and the loading means 12, a plurality of leg materials 4, 4, ... interposed between the plate materials 7 around the specimen S, a water tank 5, and a laser displacement meter 6.

[0040] A test specimen S is interposed between the upper and lower printing plates 7. In this embodiment, three test specimens S are arranged, and the printing plate 7 consists of an upper plate 71 positioned above the test specimens S and a lower plate 72 positioned below the lowest test specimen S (between the test specimen S and the base 11).

[0041] The upper plate 71 is positioned above the specimen S. The upper plate 71 consists of a main body 73 made of a stainless steel plate that is rectangular in plan view, and a pressure plate 74 formed on the lower surface of the main body 73. The pressure plate 74 is formed on the lower surface of the upper plate 71 at a position that contacts the upper surface of the specimen S. The pressure plate 74 is made of a stainless steel member that is rectangular in plan view and has a planar shape smaller than the planar shape of the main body 73. The pressure plate 74 has a thickness that exhibits sufficient resistance to the compressive force applied by the loading means 12. The shape of the upper plate 71 and the materials constituting the upper plate 71 are not limited. Also, the main body 73 and the pressure plate 74 do not necessarily have to be rectangular in plan view.

[0042] The lower plate 72 is made of a stainless steel plate material that is rectangular in plan view and is positioned opposite the upper plate 71 with the test specimen S in between. In this embodiment, the lower plate 72 has the same planar shape and thickness as the main body portion 73 of the upper plate 71. The shape and dimensions of the lower plate 72 are not limited, and it may be made of a plate material that is thinner than the upper plate 71, for example.

[0043] The contact surfaces of the upper plate 71 and the lower plate 72 with the test specimen S are provided with slip-preventing devices 75 for holding the test specimen S. The details of the slip-preventing devices 75 are the same as those of the slip-preventing devices 23 in the first embodiment, so a detailed explanation is omitted. Furthermore, the slip-preventing devices 75 may be formed as needed.

[0044] The leg members 4 are interposed between the plate materials 7 arranged vertically. In this embodiment, the leg members 4 are provided at each of the four corners of the plate material 7 so as to surround the specimen S interposed between the upper and lower plate materials 7. The details of the other leg members 4 are the same as those of the leg members 4 in the first embodiment, so a detailed explanation is omitted.

[0045] The water tank 5 is located between the plate materials 7 arranged vertically. The water tank 5 is positioned to surround the test specimen S. The other details of the water tank 5 are the same as those described in the first embodiment, so a detailed explanation is omitted.

[0046] Multiple laser displacement meters 6, 6, ... are installed on the plate material 7 (lower plate 72) located at the bottom. Laser displacement meter 6 measures the displacement of one of the multiple upper plates 71. Through holes 76 are formed in the plate material 7, which is placed between the laser displacement meter 6 and the upper plate 71 being measured by the laser displacement meter 6, corresponding to the direction of irradiation of the laser beam L of the laser displacement meter 6. For example, through holes 76 are formed in a straight line in the lower and middle upper plates 71, aligned with the direction of irradiation of the laser beam L of the laser displacement meter 6 that measures the displacement of the upper plate 71. Also, through holes 76 are formed in the lower plate 71, aligned with the direction of irradiation of the laser beam L of the laser displacement meter 6 that measures the displacement of the upper plate 71 one level above it.

[0047] The fatigue testing method using the fatigue testing apparatus 10 of the second embodiment will be described below. Figure 9 shows the fatigue testing method of the second embodiment. As shown in Figure 9, the fatigue testing method of this embodiment comprises a specimen installation step S21, a water injection step S22, and a loading step S23.

[0048] In the specimen installation process S21, the lower plate 72 is set on the base 11. Next, the specimen S is set on the lower plate 72, and the water tank 5 is placed around the specimen S. A laser displacement meter 6 is also set on the upper surface of the lower plate 72. At this time, a gap is ensured between the tip surface of the convex portion 44 and the bottom surface of the concave portion 43 of the leg member 4.

[0049] Next, the upper plate 71 is set, and the test specimen S and the water tank 5 are placed on top of it. Similarly, the upper plate 71 is set, and the test specimen S and the water tank 5 are placed on top of it. Then, once the topmost upper plate 71 is set, the loading means 12 is set from above.

[0050] In the water filling process S22, water is poured into the water tank 5. In the loading process S23, the loading means 12 repeatedly applies a load to the fatigue test fixture 13.

[0051] As described above, the fatigue testing apparatus 10 of the second embodiment provides the same effects and advantages as the fatigue testing apparatus 1 of the first embodiment. Furthermore, according to the fatigue testing apparatus 10 of the second embodiment, when fatigue testing is performed on multiple test specimens S simultaneously, only one plate material 7 is interposed between the test specimens S, making it economical.

[0052] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention. For example, although the above embodiments described the case in which a fatigue test is performed underwater, the fatigue testing apparatus 1,10 may also be used for fatigue tests in conditions other than underwater. In this case, the water tank 5 can be omitted.

[0053] The number of fatigue testing fixtures 13 that are stacked vertically is not limited. In the above embodiment, the case where there are four leg members 4 was described, but the number of leg members 4 is not limited. Also, the cross-sectional shape of the leg members 4 is not limited and may be cylindrical, for example. The device used for displacement measurement is not limited to the laser displacement meter 6. [Explanation of Symbols]

[0054] 1.10 Fatigue testing apparatus 11 Pedestal 12 Loading means 13. Fatigue testing fixture 2 Upper Edition 21 Main body 22 Pressure plate 23. Anti-slip 24 Through holes 3 Lower version 31. Anti-slip 32 Through holes 4 Leg materials 41 Upper leg member 42 Lower leg member 43 Recess 44 Convex part 45 Cross member 5 Aquariums 6. Laser displacement meter 7 Plate material 71 Upper Edition 72 Lower version 73 Main body 74 Pressure Plate 75 Anti-slip 76 Through hole S specimen L laser light

Claims

1. The first edition, A fatigue testing fixture having an upper plate and a lower plate facing each other with the test specimen in between, A fatigue testing jig characterized in that at least one of the upper plate and the lower plate is provided with a shear stopper for holding the test specimen.

2. The first edition, A lower plate facing the upper plate with the test specimen in between, A fatigue testing fixture having a plurality of leg members interposed between the upper plate and the lower plate around the specimen, The aforementioned leg member consists of an upper leg member fixed to the lower surface of the upper plate and a lower leg member fixed to the upper surface of the lower plate. A recess is formed at one end of the upper leg member and the lower leg member, and a protrusion is formed at the other end of the upper leg member and the lower leg member that can be fitted into the recess. A fatigue testing jig characterized in that the leg member is arranged such that a portion of the protrusion is inserted into the recess, and there is a gap between the tip surface of the protrusion and the bottom surface of the recess.

3. The fatigue testing jig according to claim 1 or claim 2, characterized in that a pressure plate is formed on the lower surface of the upper plate, which contacts the upper surface of the test specimen.

4. A water tank surrounding the test specimen is formed between the upper plate and the lower plate. The fatigue testing fixture according to claim 3, characterized in that the height of the water tank is greater than the height of the test specimen.

5. The base and A loading means is provided above the aforementioned base, A fatigue testing apparatus characterized by comprising, between the base and the load means described above, a fatigue testing jig according to claim 1 or claim 2, stacked vertically in multiple layers.

6. Multiple laser displacement meters are provided on the lower plate of the fatigue test fixture located at the lowest level, to measure the displacement of each of the upper plates. The fatigue testing apparatus according to claim 5, characterized in that through holes are formed in the upper plate and the lower plate, which are disposed between the laser displacement meter and the upper plate to be measured by the laser displacement meter, corresponding to the irradiation direction of the laser displacement meter.

7. The base and A loading means is provided above the aforementioned base, Multiple plate materials are arranged above and below the test specimen between the base and the loading means described above, A fatigue testing apparatus comprising a plurality of leg members interposed between the plate materials around the specimen, At least one of the upper and lower surfaces of the aforementioned printing plate is provided with a slip-preventing device for holding the test specimen. The aforementioned leg member consists of an upper leg member and a lower leg member arranged vertically. A recess is formed at one end of the upper leg member and the lower leg member, and a protrusion is formed at the other end of the upper leg member and the lower leg member that can be fitted into the recess. A fatigue testing apparatus characterized in that the leg member is arranged such that a portion of the protrusion is inserted into the recess, and there is a gap between the tip surface of the protrusion and the bottom surface of the recess.

8. A fatigue testing method using the fatigue testing apparatus described in claim 5, A test specimen installation step involves setting a columnar test specimen between the upper plate and the lower plate, A fixture installation step involves stacking the fatigue test fixtures on which the test specimens are set in multiple layers between the base and the loading means described above, A fatigue testing method characterized by comprising a loading step of repeatedly applying a load using the aforementioned loading means.

9. A fatigue testing method using the fatigue testing fixture described in claim 4, A test specimen installation step involves setting a columnar test specimen between the upper plate and the lower plate, A jig installation step involves stacking the fatigue test jig, on which the test specimen is set, in multiple layers between the base and a loading means disposed above the base. A water filling step of pouring water into the aforementioned tank, A fatigue testing method characterized by comprising a loading step of repeatedly applying a load using the aforementioned loading means.

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