Accelerated fatigue test device and method for acute-angle notch of hot-rolled U-shaped steel sheet pile

Abstract

The invention discloses a hot-rolled U-shaped steel sheet pile acute angle notch accelerated fatigue test device and method, and belongs to the technical field of hot-rolled U-shaped steel sheet pile tests, and the hot-rolled U-shaped steel sheet pile acute angle notch accelerated fatigue test device comprises a hot-rolled U-shaped steel sheet pile, a sample notch sample preparation device, an accelerated fatigue test device and a medium system device; the sample notch sample preparation device consists of a first base, a positioning structure and a sample preparation structure; the accelerated fatigue test device is composed of a second base, a clamping structure and an experimental power structure; the medium system device is composed of a low-temperature fatigue test system, a seawater corrosion medium system and a rubber soft sealing cover system. According to the hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device and method, the sample notch preparation device realizes acute-angle notch sample preparation at the intersection of the flange and the web of the U-shaped steel sheet pile, and the accelerated fatigue test device can realize a continuous fatigue test on the hot-rolled U-shaped steel sheet pile; the medium system device can simulate a low-temperature test and a seawater corrosion test on the hot-rolled U-shaped steel sheet pile.

Description

Technical Field

[0001] The invention relates to the technical field of hot-rolled U-shaped steel sheet pile testing, and in particular to a device and method for accelerating fatigue testing of a hot-rolled U-shaped steel sheet pile with an acute-angle notch. Background Art

[0002] Steel sheet piles are a new type of building material that is fast, efficient and environmentally friendly. They are widely used in construction projects such as docks, embankment revetments, retaining walls, docks, and cofferdams due to their high strength, easy installation, and no welding. Steel sheet piles are divided into cold-bent steel sheet piles and hot-rolled steel sheet piles according to the production method. During the piling construction on coastal beaches, soil acts on hot-rolled steel sheet piles. With the erosion of saline-alkali silt and seawater, the thrust of steel sheet piles against the earthwork will be affected. The failure mechanism of hot-rolled steel sheet piles is the nucleation mechanism of fatigue cracks in inclusions. It is generally believed that stress concentration in the cross section of inclusions and matrix is ​​the main cause of fatigue failure. The thermal shrinkage of inclusions and steel matrix is ​​different during the cooling process of steel. Due to the different elastic constants of inclusions and steel matrix, stress concentration is generated at the interface under the action of external stress. During the thermal deformation process of hot-rolled steel sheet piles, cracks will initiate at the interface between inclusions and matrix.

[0003] It is impossible to test and technically evaluate the fatigue resistance of hot-rolled U-shaped steel sheet piles for elevated pillars only by routine factory performance testing or internal routine testing. Yield strength testing, tensile strength testing, elongation testing, and small sample impact toughness testing belong to small sample testing of metal materials, and cannot test and evaluate the service fatigue resistance of hot-rolled U-shaped steel sheet piles for engineering structures. There is no method and device in the prior art specifically for testing the corrosion of hot-rolled U-shaped steel sheet piles in coastal areas and the fatigue resistance of earthwork and water thrust, and the quality of hot-rolled U-shaped steel sheet piles cannot be ensured. Summary of the invention

[0004] In order to solve the problem that there is no method and device for detecting the corrosion of hot-rolled U-shaped steel sheet piles in coastal areas and the fatigue strength test under earthwork and water thrust, the present invention provides a device and method for accelerating fatigue test of hot-rolled U-shaped steel sheet piles with sharp-angle notch, and the technical scheme is as follows:

[0005] The hot-rolled U-shaped steel sheet pile acute angle notch accelerated fatigue test device comprises a hot-rolled U-shaped steel sheet pile, a sample notch sample preparation device, an accelerated fatigue test device and a medium system device;

[0006] The sample notch sample preparation device is composed of a first base, a positioning structure and a sample preparation structure, a mold is arranged in the middle of the top of the first base, the positioning structure is arranged on the top of the first base, and the sample preparation structure is arranged on the bottom of the positioning structure;

[0007] The accelerated fatigue test device is composed of a second base, a clamping structure and an experimental power structure. Two load-bearing brackets are arranged on the left and right sides of the top of the second base. The clamping structure and the experimental power structure are arranged on the opposite sides of the two load-bearing brackets. The experimental power structure is located on the top of the clamping structure.

[0008] The medium system device consists of a low-temperature fatigue test system, a seawater corrosion medium system and a rubber soft sealing cover system. The low-temperature fatigue test system includes a condenser, an evaporator, a refrigeration compressor, an expansion valve and a circulating fan. The seawater corrosion medium system includes a corrosion medium storage box, a filter, a corrosion-resistant pump and a steam heat exchanger. The rubber soft sealing cover system includes an inlet three-way valve, an outlet three-way valve and a rubber soft sealing cover.

[0009] Preferably, the positioning structure includes a first hydraulic cylinder, a top seat and an adjustment structure. The first hydraulic cylinder is arranged around the top of the hot-rolled U-shaped steel sheet pile of the base. The top seat is arranged on the output shaft of the first hydraulic cylinder. Movable grooves are opened on the left and right sides of the front of the top seat. The adjustment structure is arranged on the inner side of the movable groove. The adjustment structure includes a screw rod and a movable block. The number of the screw rods is two and they are respectively arranged inside the two movable grooves. The movable block is arranged on the outer surface of the screw rod.

[0010] Preferably, the sample preparation structure comprises a moving seat, a second hydraulic cylinder and a diamond block, the moving seat is arranged at the bottom of the adjustment structure, the second hydraulic cylinder is arranged at the bottom of the moving seat, and the diamond block is arranged on the output shaft of the second hydraulic cylinder.

[0011] The setting of the positioning structure facilitates the positioning of the sample making structure. After the positioning is completed, the sample making structure can easily complete the notch sampling of the U-shaped steel sheet pile, and realize the sharp-angle notch sampling at the intersection of the flange and the web of the three-dimensional U-shaped steel sheet pile, thereby facilitating the accelerated fatigue test of the hot-rolled U-shaped steel sheet pile.

[0012] Preferably, the movable seat is arranged at the bottom of the movable block, the opposite ends of the screw rod penetrate and extend to the outside of the top seat, the opposite sides of the screw rod are provided with handles, and the left and right sides of the top of the mold are provided with grooves, and the grooves correspond to the positions of the diamond blocks and have the same inclination angles.

[0013] Preferably, the experimental power structure includes a fourth hydraulic cylinder, a test push block, a spring seat and a return spring, the fourth hydraulic cylinder and the spring seat are respectively arranged on opposite sides of two bearing brackets, the test push block is arranged on the output shaft of the fourth hydraulic cylinder, and the return spring is arranged on the side of the spring seat close to the hot-rolled U-shaped steel sheet pile.

[0014] Preferably, the clamping structure includes a third hydraulic cylinder, a first clamping block and a second clamping block, the third hydraulic cylinder is arranged on the opposite side of the two supporting brackets, the first clamping block is arranged on the output shaft of the third hydraulic cylinder on the left, and the second clamping block is arranged on the output shaft of the third hydraulic cylinder on the right.

[0015] The hot-rolled U-shaped steel sheet pile is pushed by the experimental power structure. After the hot-rolled U-shaped steel sheet pile undergoes a certain deformation, the test push block is reset. After the hot-rolled U-shaped steel sheet pile is reset by the reset spring, the above process is repeated. This reciprocating process can realize the fatigue test of the hot-rolled U-shaped steel sheet pile.

[0016] Preferably, the shapes of the opposite sides of the first clamping block and the second clamping block are respectively adapted to the outer side wall and the inner side wall of the hot-rolled U-shaped steel sheet pile.

[0017] The setting of the clamping structure can firmly fix the hot-rolled U-shaped steel sheet piles, which can effectively prevent the hot-rolled U-shaped steel sheet piles from accidentally falling off or sliding, thereby enhancing the stability of the overall structure.

[0018] Preferably, the condenser, evaporator and refrigeration compressor are connected by copper pipes, the corrosive medium storage tank, filter, corrosion-resistant pump and steam heat exchanger are connected by anti-corrosion pipes, and the top of the corrosive medium storage tank is provided with an agitator extending into the interior of the corrosive medium storage tank.

[0019] The cold air generated by the low-temperature fatigue test system will be transported by the circulating fan to the rubber soft sealing cover system to simulate the low-temperature test of the hot-rolled U-shaped steel sheet piles. The seawater corrosion medium system can pass the corrosive medium into the rubber soft sealing cover to simulate the seawater corrosion test of the hot-rolled U-shaped steel sheet piles.

[0020] The method for accelerated fatigue testing of hot-rolled U-shaped steel sheet piles with sharp notches comprises the following steps:

[0021] S1 Notch sampling: Place the hot-rolled U-shaped steel sheet pile on the mold, and adjust the position of the diamond block through the cooperation of the first hydraulic cylinder and the handle, so that the diamond block and the position where the sample is required on the hot-rolled U-shaped steel sheet pile are in the same straight line, and then start the second hydraulic cylinder to drive the diamond block to penetrate the hot-rolled U-shaped steel sheet pile and extend into the groove, so that the notch sampling of the hot-rolled U-shaped steel sheet pile can be completed, and a hot-rolled U-shaped steel sheet pile with a notch can be obtained;

[0022] S2 fatigue test: move the hot-rolled U-shaped steel sheet pile with a notch between the first clamping block and the second clamping block, and make the first clamping block and the test push block both on the same horizontal line with the hot-rolled U-shaped steel sheet pile, and ensure that the notch of the hot-rolled U-shaped steel sheet pile is not blocked by the first clamping block or the test push block, start the four third hydraulic cylinders to drive the first clamping block and the second clamping block to move to the opposite side until the hot-rolled U-shaped steel sheet pile is fixed. After the hot-rolled U-shaped steel sheet pile is fixed, start the fourth hydraulic cylinder to push the hot-rolled U-shaped steel sheet pile via the test push block, reset the test push block after the hot-rolled U-shaped steel sheet pile undergoes a certain deformation, and repeat the above process after the hot-rolled U-shaped steel sheet pile is reset by the reset spring. Repeat this process to achieve the fatigue test of the hot-rolled U-shaped steel sheet pile;

[0023] S3 Low temperature corrosion simulation: Put the rubber soft sealing cover on the hot-rolled U-shaped steel sheet pile, and make its notch located on the inner side of the rubber soft sealing cover, start the low temperature fatigue test system, so that the cold air generated by it will be transported to the refrigeration compressor by the circulating fan, and then start the simulation of the low temperature test of the hot-rolled U-shaped steel sheet pile. When the hot-rolled U-shaped steel sheet pile needs to be corroded, start the seawater corrosion medium system, pass the corrosive medium into the refrigeration compressor, and then start the simulation of the seawater corrosion test of the hot-rolled U-shaped steel sheet pile.

[0024] Preferably, the low temperature corrosion simulation in step S3 can be used alone or simultaneously in the process of the fatigue test in step S2.

[0025] Beneficial effects:

[0026] The beneficial effects produced by the technical solution of the present invention are as follows:

[0027] 1. The hot-rolled U-shaped steel sheet pile sharp-angle notch accelerated fatigue test device and method are provided with a sample notch sample making device. The setting of the positioning structure facilitates the positioning of the sample making structure. After the positioning is completed, the sample making structure can easily complete the notch sample making of the U-shaped steel sheet pile, and realizes the sharp-angle notch sample making at the intersection of the flange and the web of the three-dimensional U-shaped steel sheet pile, thereby facilitating the accelerated fatigue test of the hot-rolled U-shaped steel sheet pile.

[0028] 2. The hot-rolled U-shaped steel sheet pile sharp-angle notch accelerated fatigue test device and method are provided with an accelerated fatigue test device, and the hot-rolled U-shaped steel sheet pile is pushed by an experimental power structure. After the hot-rolled U-shaped steel sheet pile undergoes a certain deformation, the test push block is reset, and the hot-rolled U-shaped steel sheet pile is reset by a reset spring, and the above process is repeated. In this way, the fatigue test of the hot-rolled U-shaped steel sheet pile can be realized by reciprocating, and the setting of the clamping structure can firmly fix the hot-rolled U-shaped steel sheet pile, which can effectively prevent the hot-rolled U-shaped steel sheet pile from accidentally falling off or sliding, thereby enhancing the stability of the overall structure.

[0029] 3. The hot-rolled U-shaped steel sheet pile sharp-angle notch accelerated fatigue test device and method are provided with a medium system device. The cold air generated by the low-temperature fatigue test system will be transported to the rubber soft sealing cover system by the circulating fan to simulate the low-temperature test of the hot-rolled U-shaped steel sheet pile. The seawater corrosion medium system can pass the corrosive medium into the rubber soft sealing cover to simulate the seawater corrosion test of the hot-rolled U-shaped steel sheet pile, and can be used together with the accelerated fatigue test device at the same time to make the test effect better and more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a schematic diagram of the front view structure of a sample notch sample preparation device of a hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device and method of the present invention;

[0032] Figure 2 It is a three-dimensional structural schematic diagram of a sample notch sample preparation device of a hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device and method of the present invention;

[0033] Figure 3 It is a schematic diagram of the three-dimensional structure of the accelerated fatigue test device of the hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device and method of the present invention;

[0034] Figure 4 It is a front view structural schematic diagram of an accelerated fatigue test device of an acute-angle notch accelerated fatigue test device and method for hot-rolled U-shaped steel sheet piles of the present invention;

[0035] Figure 5 It is a schematic diagram of the overall system of the medium system device of the hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device and method of the present invention.

[0036] In the figure, 1. hot-rolled U-shaped steel sheet pile; 2. first base; 3. mold; 4. first hydraulic cylinder; 5. top seat; 6. screw rod; 7. movable block; 8. moving seat; 9. second hydraulic cylinder; 10. diamond block; 11. handle; 12. groove; 13. second base; 14. bearing bracket; 15. third hydraulic cylinder; 16. first clamping block; 17. second clamping block; 18. spring seat; 19. return spring; 20. fourth hydraulic cylinder; 21. test push block; 22. condenser; 23. evaporator; 24. refrigeration compressor; 25. expansion valve; 26. circulating fan; 27. corrosive medium storage box; 28. filter; 29. ​​corrosion-resistant pump; 30. steam heat exchanger; 31. agitator; 32. inlet three-way valve; 33. outlet three-way valve; 34. rubber soft sealing cover. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] like Figure 1-2 As shown, the hot-rolled U-shaped steel sheet pile acute angle notch accelerated fatigue test device and method include a hot-rolled U-shaped steel sheet pile 1, a sample notch sample preparation device, an accelerated fatigue test device and a medium system device;

[0039] The sample notch sample preparation device is composed of a first base 2, a positioning structure and a sample preparation structure. A mold 3 is arranged in the middle of the top of the first base 2, the positioning structure is arranged on the top of the first base 2, and the sample preparation structure is arranged at the bottom of the positioning structure.

[0040] The positioning structure includes a first hydraulic cylinder 4, a top seat 5 and an adjustment structure. The first hydraulic cylinder 4 is arranged around the top of the base hot-rolled U-shaped steel sheet pile 1. The top seat 5 is arranged on the output shaft of the first hydraulic cylinder 4. The left and right sides of the front of the top seat 5 are provided with movable grooves. The adjustment structure is arranged on the inner side of the movable groove. The positioning structure can conveniently complete the positioning of the sample preparation structure.

[0041] The adjustment structure includes a screw rod 6 and a movable block 7. The screw rods 6 are two in number and are respectively arranged inside the two movable grooves. The movable block 7 is arranged on the outer surface of the screw rod 6. The adjustment structure is used to adjust the positions of the two diamond blocks 10, which facilitates the positioning when the notch is prepared.

[0042] The sample preparation structure includes a moving seat 8, a second hydraulic cylinder 9 and a diamond block 10. The moving seat 8 is arranged at the bottom of the adjustment structure, the second hydraulic cylinder 9 is arranged at the bottom of the moving seat 8, and the diamond block 10 is arranged on the output shaft of the second hydraulic cylinder 9.

[0043] Specifically, the movable seat 8 is arranged at the bottom of the movable block 7, the opposite ends of the screw rod 6 penetrate and extend to the outside of the top seat 5, the opposite sides of the screw rod 6 are provided with handles 11, and grooves 12 are provided on the left and right sides of the top of the mold 3. The grooves 12 correspond to the positions of the diamond blocks 10 and have the same inclination angle to avoid damage to the mold 3 during sample preparation.

[0044] In this embodiment, the sample notch sampling device can conveniently complete the notch sampling of the U-shaped steel sheet pile, realizing the sharp-angle notch sampling at the intersection of the flange and the web of the three-dimensional hot-rolled U-shaped steel sheet pile 1, thereby facilitating the accelerated fatigue test of the hot-rolled U-shaped steel sheet pile 1.

[0045] like Figure 3-4 As shown, the accelerated fatigue test device is composed of a second base 13, a clamping structure and an experimental power structure. Two load-bearing brackets 14 are arranged on the left and right sides of the top of the second base 13. The clamping structure and the experimental power structure are arranged on the opposite side of the two load-bearing brackets 14, and the experimental power structure is located on the top of the clamping structure.

[0046] The experimental power structure includes a fourth hydraulic cylinder 20, a test push block 21, a spring seat 18 and a return spring 19. The fourth hydraulic cylinder 20 and the spring seat 18 are respectively arranged on opposite sides of the two bearing brackets 14. The test push block 21 is arranged on the output shaft of the fourth hydraulic cylinder 20. The return spring 19 is arranged on the side of the spring seat 18 close to the hot-rolled U-shaped steel sheet pile 1. The experimental power structure can perform fatigue tests on the hot-rolled U-shaped steel sheet pile 1 in a reciprocating manner.

[0047] The clamping structure includes a third hydraulic cylinder 15, a first clamping block 16 and a second clamping block 17. The third hydraulic cylinder 15 is arranged on the opposite side of the two supporting brackets 14. The first clamping block 16 is arranged on the output shaft of the third hydraulic cylinder 15 on the left side, and the second clamping block 17 is arranged on the output shaft of the third hydraulic cylinder 15 on the right side. The clamping structure can firmly fix the hot-rolled U-shaped steel sheet pile 1 and can effectively prevent the hot-rolled U-shaped steel sheet pile 1 from accidentally falling off or sliding.

[0048] Specifically, the shapes of the opposite sides of the first clamping block 16 and the second clamping block 17 are respectively adapted to the outer side wall and the inner side wall of the hot-rolled U-shaped steel sheet pile 1, so that the hot-rolled U-shaped steel sheet pile 1 is fixed more firmly.

[0049] In this embodiment, the accelerated fatigue testing device can perform fatigue tests on the hot-rolled U-shaped steel sheet piles 1 repeatedly and firmly fix the hot-rolled U-shaped steel sheet piles 1, thereby effectively preventing the hot-rolled U-shaped steel sheet piles 1 from accidentally falling off or sliding.

[0050] like Figure 5 As shown, the medium system device consists of a low-temperature fatigue test system, a seawater corrosion medium system and a rubber soft sealing cover system. The low-temperature fatigue test system includes a condenser 22, an evaporator 23, a refrigeration compressor 24, an expansion valve 25 and a circulating fan 26. The seawater corrosion medium system includes a corrosive medium storage box 27, a filter 28, a corrosion-resistant pump 29 and a steam heat exchanger 30. The rubber soft sealing cover system includes an inlet three-way valve 32, an outlet three-way valve 33 and a rubber soft sealing cover 34. The condenser 22, the evaporator 23 and the refrigeration compressor 24 are all connected by copper pipes. The corrosive medium storage box 27, the filter 28, the corrosion-resistant pump 29 and the steam heat exchanger 30 are all connected by anti-corrosion pipes. The top of the corrosive medium storage box 27 is provided with an agitator 31 extending to the inside of the corrosive medium storage box 27.

[0051] In this embodiment, the medium system device can simulate the low temperature test and seawater corrosion test of the hot-rolled U-shaped steel sheet pile 1, and can be used together with the accelerated fatigue test device at the same time to make the test effect better and more efficient.

[0052] The method for accelerated fatigue testing of hot-rolled U-shaped steel sheet piles with sharp notches comprises the following steps:

[0053] S1 notch sampling: Place the hot-rolled U-shaped steel sheet pile 1 on the mold 3, and adjust the position of the diamond block 10 through the cooperation of the first hydraulic cylinder 4 and the handle 11, so that the diamond block 10 and the position on the hot-rolled U-shaped steel sheet pile 1 where the sample needs to be prepared are in the same straight line, and then start the second hydraulic cylinder 9 to drive the diamond block 10 to penetrate the hot-rolled U-shaped steel sheet pile 1 and extend to the inside of the groove 12, so that the notch sampling of the hot-rolled U-shaped steel sheet pile 1 can be completed, and the hot-rolled U-shaped steel sheet pile 1 with a notch can be obtained;

[0054] S2 fatigue test: move the hot-rolled U-shaped steel sheet pile 1 with a notch to between the first clamping block 16 and the second clamping block 17, and make the first clamping block 16 and the test push block 21 both on the same horizontal line with the hot-rolled U-shaped steel sheet pile 1, and ensure that the notch of the hot-rolled U-shaped steel sheet pile 1 is not blocked by the first clamping block 16 or the test push block 21, start the four third hydraulic cylinders 15 to drive the first clamping block 16 and the second clamping block 17 to move to the opposite side until the hot-rolled U-shaped steel sheet pile 1 is fixed. After the hot-rolled U-shaped steel sheet pile 1 is fixed, start the fourth hydraulic cylinder 20 to push the hot-rolled U-shaped steel sheet pile 1 via the test push block 21, reset the test push block 21 after the hot-rolled U-shaped steel sheet pile 1 undergoes a certain deformation, and repeat the above process after the hot-rolled U-shaped steel sheet pile 1 is reset by the reset spring 19. Repeat this process, and the fatigue test of the hot-rolled U-shaped steel sheet pile 1 can be achieved by repeating this process.

[0055] S3 Low temperature corrosion simulation: The rubber soft sealing cover 34 is sleeved on the hot-rolled U-shaped steel sheet pile 1, and the notch is located on the inner side of the rubber soft sealing cover 34, and the low temperature fatigue test system is started so that the cold air generated by it will be transported to the refrigeration compressor 24 by the circulating fan 26, and the low temperature test of the hot-rolled U-shaped steel sheet pile 1 can be simulated. When the hot-rolled U-shaped steel sheet pile 1 needs to be subjected to a corrosion test, the seawater corrosion medium system is started, and the corrosive medium is passed into the refrigeration compressor 24, and the seawater corrosion test of the hot-rolled U-shaped steel sheet pile 1 can be simulated.

[0056] The test principle of the present invention is: a diamond-shaped hole is punched at the intersection of the flange and the web of the hot-rolled U-shaped steel sheet pile 1 with a rounded corner to achieve a sharp-angle crack notch, resulting in stress concentration in the notch. At the same time, seawater corrodes and penetrates the notch, and then a fatigue test is carried out at a low temperature to achieve an accelerated corrosion fatigue test, thereby solving the technical problem that the prior art lacks a method and device for detecting corrosion in coastal areas of the hot-rolled U-shaped steel sheet pile 1 and fatigue strength testing against earthwork and water thrust.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Hot-rolled U-shaped steel sheet pile acute angle notch accelerated fatigue test device, characterized in that: include: Hot-rolled U-shaped steel sheet pile (1), a specimen notch sample preparation device, an accelerated fatigue test device and a medium system device; The sample notch sample preparation device comprises a first base (2), a positioning structure and a sample preparation structure, wherein a mold (3) is arranged in the middle of the top of the first base (2), the positioning structure is arranged at the top of the first base (2), and the sample preparation structure is arranged at the bottom of the positioning structure; The accelerated fatigue test device is composed of a second base (13), a clamping structure and an experimental power structure. Two bearing brackets (14) are arranged on the left and right sides of the top of the second base (13). The clamping structure and the experimental power structure are arranged on opposite sides of the two bearing brackets (14). The experimental power structure is located on the top of the clamping structure. The medium system device is composed of a low-temperature fatigue test system, a seawater corrosion medium system and a rubber soft sealing cover system. The low-temperature fatigue test system includes a condenser (22), an evaporator (23), a refrigeration compressor (24), an expansion valve (25) and a circulating fan (26). The seawater corrosion medium system includes a corrosion medium storage tank (27), a filter (28), a corrosion-resistant pump (29) and a steam heat exchanger (30). The rubber soft sealing cover system includes an inlet three-way valve (32), an outlet three-way valve (33) and a rubber soft sealing cover (34).

2. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 1, characterized in that: The positioning structure comprises a first hydraulic cylinder (4), a top seat (5) and an adjustment structure. The first hydraulic cylinder (4) is arranged around the top of the base hot-rolled U-shaped steel sheet pile (1). The top seat (5) is arranged on the output shaft of the first hydraulic cylinder (4). The left and right sides of the front of the top seat (5) are both provided with movable grooves. The adjustment structure is arranged on the inner side of the movable groove. The adjustment structure comprises a screw rod (6) and a movable block (7). The number of the screw rods (6) is two and they are respectively arranged inside two movable grooves. The movable block (7) is arranged on the outer surface of the screw rod (6).

3. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 2, characterized in that: The sample preparation structure comprises a moving seat (8), a second hydraulic cylinder (9) and a diamond block (10); the moving seat (8) is arranged at the bottom of the adjustment structure, the second hydraulic cylinder (9) is arranged at the bottom of the moving seat (8), and the diamond block (10) is arranged on the output shaft of the second hydraulic cylinder (9).

4. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 3, characterized in that: The movable seat (8) is arranged at the bottom of the movable block (7), the opposite ends of the screw rod (6) penetrate and extend to the outside of the top seat (5), the opposite sides of the screw rod (6) are provided with handles (11), and the left and right sides of the top of the mold (3) are provided with grooves (12), and the grooves (12) correspond to the positions of the diamond blocks (10) and have the same inclination angles.

5. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 1, characterized in that: The experimental power structure comprises a fourth hydraulic cylinder (20), a test push block (21), a spring seat (18) and a return spring (19); the fourth hydraulic cylinder (20) and the spring seat (18) are respectively arranged on opposite sides of two bearing brackets (14); the test push block (21) is arranged on the output shaft of the fourth hydraulic cylinder (20); and the return spring (19) is arranged on a side of the spring seat (18) close to the hot-rolled U-shaped steel sheet pile (1).

6. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 5, characterized in that: The clamping structure comprises a third hydraulic cylinder (15), a first clamping block (16) and a second clamping block (17); the third hydraulic cylinder (15) is arranged on one side opposite to the two supporting brackets (14); the first clamping block (16) is arranged on the output shaft of the left third hydraulic cylinder (15); and the second clamping block (17) is arranged on the output shaft of the right third hydraulic cylinder (15).

7. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 6, characterized in that: The shapes of the opposite sides of the first clamping block (16) and the second clamping block (17) are respectively adapted to the outer side wall and the inner side wall of the hot-rolled U-shaped steel sheet pile (1).

8. The hot-rolled U-shaped steel sheet pile acute-angle notch accelerated fatigue test device according to claim 1, characterized in that: The condenser (22), evaporator (23) and refrigeration compressor (24) are connected by copper pipes, the corrosive medium storage tank (27), filter (28), corrosion-resistant pump (29) and steam heat exchanger (30) are connected by anti-corrosion pipes, and the top of the corrosive medium storage tank (27) is provided with an agitator (31) extending into the interior of the corrosive medium storage tank (27).

9. The method for accelerated fatigue testing of hot-rolled U-shaped steel sheet piles with acute angle notches according to claims 1-8, characterized in that: The following steps are involved: S1 notch sampling: placing the hot-rolled U-shaped steel sheet pile (1) on the mold (3), adjusting the position of the rhombus block (10) through the cooperation of the first hydraulic cylinder (4) and the handle (11), so that the rhombus block (10) and the position on the hot-rolled U-shaped steel sheet pile (1) where the sampling is required are on the same straight line, and then starting the second hydraulic cylinder (9) to drive the rhombus block (10) to penetrate the hot-rolled U-shaped steel sheet pile (1) and extend to the inside of the groove (12), so that the notch sampling of the hot-rolled U-shaped steel sheet pile (1) is completed, and the hot-rolled U-shaped steel sheet pile (1) with a notch is obtained; S2 fatigue test: The hot-rolled U-shaped steel sheet pile (1) with a notch is moved between the first clamping block (16) and the second clamping block (17), and the first clamping block (16) and the test push block (21) are both on the same horizontal line with the hot-rolled U-shaped steel sheet pile (1), and it is ensured that the notch of the hot-rolled U-shaped steel sheet pile (1) is not blocked by the first clamping block (16) or the test push block (21), and the four third hydraulic cylinders (15) are started to drive the first clamping block (16) and the second clamping block (17) to move. 7) moving to the opposite side until the hot-rolled U-shaped steel sheet pile (1) is fixed. After the hot-rolled U-shaped steel sheet pile (1) is fixed, the fourth hydraulic cylinder (20) is started to push the hot-rolled U-shaped steel sheet pile (1) via the test push block (21). After the hot-rolled U-shaped steel sheet pile (1) undergoes a certain deformation, the test push block (21) is reset. After the hot-rolled U-shaped steel sheet pile (1) is reset via the reset spring (19), the above process is repeated. In this way, the fatigue test of the hot-rolled U-shaped steel sheet pile (1) can be realized by repeating the process. S3 low temperature corrosion simulation: the rubber soft sealing cover (34) is sleeved on the hot-rolled U-shaped steel sheet pile (1), and the notch is located on the inner side of the rubber soft sealing cover (34). The low temperature fatigue test system is started so that the cold air generated by it is transported to the refrigeration compressor (24) by the circulating fan (26). Then, the low temperature test of the hot-rolled U-shaped steel sheet pile (1) can be simulated. When the hot-rolled U-shaped steel sheet pile (1) needs to be subjected to a corrosion test, the seawater corrosion medium system is started and the corrosive medium is passed into the refrigeration compressor (24). Then, the seawater corrosion test of the hot-rolled U-shaped steel sheet pile (1) can be simulated.

10. The method for accelerated fatigue testing of hot-rolled U-shaped steel sheet pile acute-angle notch according to claim 9, characterized in that: The low temperature corrosion simulation in step S3 can be used alone or simultaneously in the process of the fatigue test in step S2.

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