Tensile fatigue test device based on portal frame electro-hydraulic servo loading test system

Abstract

The present invention discloses a tensile fatigue test device based on a portal frame electro-hydraulic servo loading test system, comprising a reaction foundation, a portal loading frame, a hydraulic servo actuator, a support, and a plurality of tie rods. The upper end of the hydraulic servo actuator is connected to the main loading beam of the portal loading frame, and the lower end is suspended above the support; each tie rod is symmetrically arranged on both sides of the hydraulic servo actuator, and one end of the tie rod is connected to the bottom of the fixed part of the hydraulic servo actuator, and the other end is connected to the column bolt of the portal loading frame. The connection between the upper end of the test component and the actuator head of the hydraulic servo actuator and the connection between the lower end of the test component and the support are both movable connections. It can be seen that the present invention can ensure that the hydraulic servo actuator is always in a vertical state by adjusting the tie rods, and can eliminate the uneven tension phenomenon of the test component caused by the center of the support being not completely perpendicular to the center of the hydraulic servo actuator.

Description

Technical Field

[0001] The invention relates to a component static loading or fatigue loading test, in particular to a tensile fatigue testing device based on a portal frame electro-hydraulic servo loading testing system. Background Art

[0002] The fatigue problem of steel structures in civil engineering is prominent. At the same time, with the rapid development of new materials in civil engineering in recent years, the fatigue properties of structures and new materials have become a hot topic of research in major universities and research institutes.

[0003] Fatigue loading testing machines are the core experimental equipment for fatigue research. The most common types are press fatigue machines for testing bending fatigue in beams and electro-hydraulic servo fatigue machines for testing tensile fatigue in plates. Press fatigue machines are suitable for large components such as beams. Loaded by the machine's indenter, they can study the cracking characteristics, bearing capacity, and fatigue properties of beams under cyclic loading. Electro-hydraulic servo fatigue machines are suitable for smaller components such as steel plates and wires, using hydraulic chucks to clamp the specimens for tensile fatigue loading.

[0004] In building structures and bridge engineering, computer-controlled gantry loading frame electro-hydraulic servo test systems are commonly used. The gantry loading frame is installed on the reaction foundation of the "T"-shaped reaction groove through ground rivets. The hydraulic servo actuator is connected to the main loading beam through a ball joint and is in a suspended state. The lower part of the hydraulic servo actuator piston rod is connected to the pressure head through a ball joint. This test system is widely used for bending tests and bending fatigue tests of components. For tensile fatigue tests, especially tensile fatigue tests of large-sized components that require large tensile forces, the upper and lower ball joints of the hydraulic servo actuator in this test system are installed with no gap and tight fit. A large-mass electro-hydraulic valve block is installed on one side of the hydraulic servo actuator cylinder. The electro-hydraulic valve block is connected to a multi-channel oil pipe. The reciprocating impact of the oil on the oil pipe will produce strong vibration. Therefore, the hydraulic servo actuator in the natural suspension state is not in a vertical state. The geometric center line of the tension member does not coincide with the geometric center line of the hydraulic servo actuator piston rod, and there is a certain angle. During the tensile fatigue test, the upper part of the tensile member will swing left and right, vibrate violently and the force is uneven. Therefore, the portal loading frame electro-hydraulic servo test system cannot effectively carry out tensile fatigue tests on large-scale steel members with large tension. Summary of the Invention

[0005] The purpose of the present invention is to provide a tensile fatigue test device based on a portal frame electro-hydraulic servo loading test system to meet the requirements of large-load tensile fatigue tests on components such as steel plates and steel bars.

[0006] To this end, the present invention provides the following solutions:

[0007] A tensile fatigue testing device based on a portal frame electro-hydraulic servo loading testing system includes a reaction foundation, a portal loading frame, a hydraulic servo actuator and a support. The portal loading frame and the support are respectively fixedly installed on the reaction foundation. The upper end of the hydraulic servo actuator is connected to the main loading beam of the portal loading frame, and the lower end is suspended above the support. The upper and lower ends of the test component are respectively connected to the actuating head and the support of the hydraulic servo actuator, and also include a plurality of tie rods; each tie rod is symmetrically arranged on both sides of the hydraulic servo actuator, and one end of the tie rod is connected to the bottom of the fixed part of the hydraulic servo actuator, and the other end is connected to the column bolt of the portal loading frame; the connection method between the upper end of the test component and the actuating head of the hydraulic servo actuator and the connection method between the lower end of the test component and the support are both movable connections.

[0008] Preferably, the hydraulic servo actuator is a hydraulic cylinder, and each of the four fastening screws of the hydraulic cylinder is provided with a connecting fastener near the bottom of the hydraulic cylinder; there are four tie rods; the inner ends of the tie rods are connected one-to-one with the connecting fasteners.

[0009] Preferably, the outer end of the tie rod is provided with a thread, and the outer end of the tie rod is passed through the corresponding mounting hole on the column of the portal loading frame and is locked by a nut; by adjusting the position of each nut on the corresponding tie rod, the connection length of the tie rod between the hydraulic servo actuator cylinder and the column is adjusted to achieve vertical adjustment of the hydraulic servo actuator cylinder.

[0010] Preferably, the upper end of the test component is connected to the actuating head of the hydraulic servo actuator via an upper clamping connector and two upper clamping plates; wherein: the upper clamping connector is connected to the actuating head of the hydraulic servo actuator; and a first through hole is provided through the middle position of the upper clamping connector, and a spherical pit is provided at the middle position of the upper clamping connector on the side facing the actuating head; the upper part of the test component passes through the first through hole and is bolted to the two upper clamping plates affixed to the upper clamping connector; the joints of the two upper clamping plates and the upper clamping connector are provided with spherical protrusions that match the spherical pits.

[0011] Preferably, the upper clamping connector includes a fixed plate and two side plates; a side plate is provided on each side of the fixed plate, and the two side plates are connected to the actuating head of the hydraulic servo actuator through a first bolt; a first through hole is provided at the middle position of the fixed plate, and a spherical pit is provided at the middle position of the fixed plate on the side facing the actuating head; the two upper clamping plates are affixed to the upper plate surface of the fixed plate.

[0012] Preferably, the side plate is provided with a screw hole, in which a third bolt is screwed; the head of the third bolt is lathe-machined to have an outer diameter the same as the thickness of the test component, and the third bolt is inserted between the two upper plates and tightens against the test component.

[0013] Preferably, the lower end of the test component is connected to the support through two lower plywood and a pin; a second through hole for the test component is provided in the center of the upper panel of the support; the lower part of the test component is bolted to the two lower plywood placed on the upper panel of the support and passes through the second through hole, and is connected to the support through a pin.

[0014] Preferably, the two lower clamping plates are provided with shaft holes, and the latch pins are inserted into the shaft holes.

[0015] Preferably, the latch is an arc-shaped circular cross-section latch, and circular bottom grooves are provided at the outer circles on both sides of the latch, and corresponding round rods are placed in the circular bottom grooves, and the round rods are tightly against the upper panel of the support.

[0016] Preferably, the support is connected to the reaction foundation of the "T"-shaped reaction groove on the ground through a second bolt.

[0017] Compared with the prior art, the present invention has achieved the following technical effects:

[0018] 1. By providing a restraining device for the tie rod, this invention maintains the hydraulic servo actuator in a vertical position, eliminating the jitter and creep effect caused by the offset of the electro-hydraulic valve block and the reciprocating impact of oil on the oil pipe during tensile fatigue testing. Furthermore, by providing compensation mechanisms at the upper and lower portions of the test component, the connection between the test component and the piston rod and support of the hydraulic servo actuator, respectively, is flexible, eliminating the uneven tensile force caused by the center of the support not being completely perpendicular to the center of the hydraulic servo actuator.

[0019] 2. The present invention movably connects the upper end of the test component to the fixed plate through an upper splint (matching spherical pits and spherical protrusions), and movably connects the lower end of the test component to the support through a lower splint (the shape of the hole wall of the axial hole matches the arc-shaped pin, and the outer circles on both sides of the pin are provided with round-bottomed grooves, and round rods adapted to them are placed in the round-bottomed grooves. The round rods are tightly against the upper panel of the support, and the test component can be movably rotated in two orthogonal directions through the lower splint, the pin and the round rod), thereby eliminating the uneven tension of the test component caused by the non-perpendicularity between the center of the support and the center of the hydraulic servo actuator, so that the geometric centers of the test component and the piston rod of the hydraulic servo actuator correspond to each other and are in the same direction, thereby achieving ideal experimental results.

[0020] In summary, the present invention expands the application of the portal frame electro-hydraulic servo loading test system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a structural diagram of the portal frame electro-hydraulic servo loading test system of this embodiment;

[0023] Figure 2 This is a schematic diagram of the verticality constraint structure of the hydraulic servo actuator in this embodiment;

[0024] Figure 3 This is a structural diagram of the fixed plate and side plates of this embodiment;

[0025] Figure 4 This is a schematic diagram of the test component installation structure for the "Bolt-connected Steel Structure Fatigue Test" in this embodiment.

[0026] Explanation of the accompanying symbols: 1. Test component; 2. Tie rod; 3. Fixing plate; 4. Support; 5. Hydraulic servo actuator; 6. Column; 7. Side plate; 8. Actuating head; 9. First bolt; 10. First through hole; 11. Spherical pit; 12. Upper panel; 13. Second through hole; 14. Second bolt; 15. Reaction foundation; 16. Upper clamping plate; 17. Lower clamping plate; 18. Pin; 19. Main loading beam; 20. Ball joint; 21. Electro-hydraulic valve block; 22. Oil pipe; 23. Piston rod; 24. Fastening screw; 25. Mounting hole; 26. Connecting fastener; 27. Wedge washer; 28. Nut; 29. ​​Third bolt; 30. Spherical protrusion; 31. Shaft hole; 32. Round bottom groove; 33. Round rod. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The technical concept of the tensile fatigue testing device based on the portal frame electro-hydraulic servo loading test system provided by the present invention is: on the one hand, the bottom of the hydraulic servo actuator cylinder is connected to the column of the portal loading frame through a tie rod, so that the hydraulic servo actuator is in a vertical state; on the other hand, the upper part of the test component is connected to the hydraulic servo actuator through a fixed plate, and the lower part is connected to the reaction force foundation of the "T"-shaped reaction groove on the ground through a support, and a movable connection (compensation mechanism) is set at the connection between the test component and the fixed plate and the support, thereby eliminating the uneven tension of the test component caused by the center of the support and the center of the hydraulic servo actuator not being completely perpendicular.

[0029] Specifically, if Figure 1-4 As shown, this embodiment provides a tensile fatigue test device based on a portal frame electro-hydraulic servo loading test system, wherein the test component 1 is a high-strength steel bolt connector, including a tie rod 2, a fixing plate 3, and a support 4. One end of the tie rod 2 is connected to the bottom of the oil cylinder of the hydraulic servo actuator 5, and the other end is screwed and bolted to the column 6 of the portal loading frame; side plates 7 are provided on both sides of the fixing plate 3, and the side plates 7 are tightly against the actuating head 8 of the hydraulic servo actuator. The fixing plate 3 is installed below the actuating head 8 of the hydraulic servo actuator 5 by a first bolt 9. The center of the fixing plate 3 is provided with a test component 1 has a first through hole 10 and a spherical pit 11 is provided on one side of the actuator head 8 at the center thereof, the concave surface of the spherical pit 11 is ground and polished, a second through hole 13 of the test component 1 is provided at the center of the upper panel 12 of the support 4, and the support 4 is connected to the reaction foundation 15 of the "T"-shaped reaction groove on the ground through a second bolt 14; the upper part of the test component 1 passes through the first through hole 10 and is bolted to two upper plywood 16, and the lower part of the test component 1 is bolted to two lower plywood 17 and passes through the second through hole 13, and is connected to the support 4 through a pin 18.

[0030] The present invention of the above scheme eliminates the phenomenon that the hydraulic servo actuator 5 suspended from the main loading beam 19 in the original loading system is always in a non-vertical state due to factors such as the difficulty in rotating the upper and lower ball joints 20, the offset installation of the electro-hydraulic valve block 21 installed on one side, and the reciprocating impact of the oil pipe 22 by the oil. The influence of residual factors on the test, such as the deviation of the geometric center line of the test component 1 from the geometric center of the piston rod 23 of the hydraulic servo actuator 5 due to the inaccurate installation position of the support 4 on the reaction foundation 15, is eliminated by the compensation structure provided at both ends of the test component 1. Example 1

[0031] like Figures 1 and 2The two ends of the oil cylinder of the hydraulic servo actuator 5 are fixed by four fastening screws 24. The four columns 6 of the existing portal loading frame have multiple vertically arranged mounting holes 25 for installing the main loading beam 19. Four tie rods 2 are provided to constrain the vertical position of the hydraulic servo actuator 5; the tie rod 2 is a steel round bar, and one end of the tie rod 2 is fixedly connected to the fastening screw 24 by providing a connecting fastener 26. The other end of the tie rod 2 passes through the mounting hole 25 at the same height, and a thread is provided on the tie rod 2 at this end and a wedge-shaped gasket 27 is added. The fixed connection between the tie rod 2 and the column 6 is achieved by a nut 28; the nut 28 is adjusted to adjust the connection length of the tie rod 2, so that the hydraulic servo actuator 5 can be kept in a vertical state. Example 2

[0032] like Figure 1 、 Figures 2-4 The test component 1 is a "bolted structural steel component". Accordingly, the first through hole 10 in the center of the fixing plate 3 is rectangular, and the concave surface of the spherical pit 11 is ground and polished. The side plate 7 is provided with a screw hole, and a third bolt 29 is screwed into the screw hole. The head of the third bolt is processed by a lathe to have an outer diameter with the same thickness as the test component 1. The third bolt 29 is inserted between the two upper clamping plates 16 and presses against the test component 1, so that the test component 1 is installed in the center of the first through hole 10; the bottom of the upper clamping plate 16 is provided with a spherical protrusion 3 that matches the spherical pit 11 0, the test component 1 can be rotatable through the spherical protrusions 30 on the two upper splints 16; the lower splint 17 is provided with an axial hole 31, and the plug 18 is inserted into the axial hole 31. The plug 18 is an arc-shaped circular cross-section plug. Correspondingly, the hole wall shape of the axial hole 31 also matches the arc-shaped plug 18. The outer circle of both sides of the plug 18 is provided with a round bottom groove 32, and a round rod 33 adapted thereto is placed in the round bottom groove 32. The round rod 33 is tightly against the upper panel 12 of the support 4. The test component 1 can be rotatable in two orthogonal directions through the lower splint 17, the plug 18 and the round rod 33.

[0033] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above examples is intended only to facilitate understanding of the method and core concept of the present invention. Furthermore, those skilled in the art will appreciate that, based on the principles of the present invention, variations in the specific implementation methods and scope of application will allow for the implementation of the present invention's tensile fatigue testing device based on a portal frame electro-hydraulic servo loading test system. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A tensile fatigue test device based on a gantry frame electro-hydraulic servo loading test system, comprising a reaction foundation, a gantry loading frame, a hydraulic servo actuator, a fatigue test fixture, and a support. The gantry loading frame and the support are respectively fixedly mounted on the reaction foundation. The upper end of the hydraulic servo actuator is connected to the main loading beam of the gantry loading frame, and the lower end is suspended above the support. The test component is placed in the fatigue test fixture. The upper and lower ends of the fatigue test fixture are respectively connected to the actuating head and the support of the hydraulic servo actuator. The device is characterized in that: It also includes several tie rods; Each tie rod is symmetrically arranged on both sides of the hydraulic servo actuator, and one end of the tie rod is connected to the bottom of the fixed part of the hydraulic servo actuator, and the other end is connected to the column bolt of the portal loading frame; The connection between the upper end of the fatigue test fixture and the actuator head of the hydraulic servo actuator and the connection between the lower end of the test component and the support are both movable connections; The upper end of the fatigue test fixture is connected to the actuating head of the hydraulic servo actuator via an upper clamping connector and two upper clamping plates; wherein: the upper clamping connector is connected to the actuating head of the hydraulic servo actuator, and a first through hole is formed through the middle of the upper clamping connector, and a spherical recess is formed in the middle of the upper clamping connector on a side facing the actuating head; The upper portion of the fatigue test fixture passes through the first through hole and is bolted to the two upper clamping plates attached to the upper clamping connector; The joints between the two upper clamping plates and the upper clamping connector are provided with spherical protrusions that match the spherical recesses; The lower end of the fatigue test fixture is connected to the support via two lower clamping plates and a latch; wherein a second through hole for the fatigue test fixture is provided at the center of the upper panel of the support; the lower portion of the fatigue test fixture is bolted to the two lower clamping plates placed on the upper panel of the support, passes through the second through hole, and is connected to the support via a latch; The latch is an arc-shaped circular cross-section latch, and circular bottom grooves are provided at the outer circles of both sides of the latch. Appropriate round rods are placed in the circular bottom grooves, and the round rods are tightly against the upper panel of the support.

2. The tensile fatigue testing device based on the portal frame electro-hydraulic servo loading testing system according to claim 1 is characterized in that: The hydraulic servo actuator is a hydraulic cylinder, and each of the four fastening screws of the hydraulic cylinder is provided with a connecting fastener near the bottom of the hydraulic cylinder; there are four tie rods; the inner ends of the tie rods are connected one-to-one with the connecting fasteners.

3. The tensile fatigue test device based on the portal frame electro-hydraulic servo loading test system according to claim 2 is characterized in that: The outer end of the tie rod is provided with a thread, and the outer end of the tie rod is passed through the corresponding mounting hole on the column of the portal loading frame and then locked by a nut; by adjusting the position of each nut on the corresponding tie rod, the connection length of the tie rod between the hydraulic servo actuator cylinder and the column is adjusted to achieve vertical adjustment of the hydraulic servo actuator cylinder.

4. The tensile fatigue testing device based on the portal frame electro-hydraulic servo loading testing system according to claim 1 is characterized in that: The upper clamping connector includes a fixed plate and two side plates; a side plate is provided on each side of the fixed plate, and the two side plates are connected to the actuating head of the hydraulic servo actuator through a first bolt; a first through hole is provided at the middle position of the fixed plate, and a spherical pit is provided at the middle position of the fixed plate on the side facing the actuating head; the two upper clamping plates are affixed to the upper plate surface of the fixed plate.

5. The tensile fatigue testing device based on the portal frame electro-hydraulic servo loading testing system according to claim 4 is characterized in that: The side plate is provided with a screw hole, in which a third bolt is screwed; the head of the third bolt is processed by a lathe to have an outer diameter the same as the thickness of the test component, and the third bolt is inserted between the two upper clamping plates and tightens the test component.

6. The tensile fatigue testing device based on the portal frame electro-hydraulic servo loading testing system according to claim 1 is characterized in that: The two lower clamping plates are provided with shaft holes, and the latch pins are inserted into the shaft holes.

7. The tensile fatigue testing device based on the portal frame electro-hydraulic servo loading testing system according to claim 1 is characterized in that: The support is connected to the reaction foundation of the "T"-shaped reaction groove on the ground through a second bolt.

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