A suspension bridge main cable steel wire bending friction corrosion fatigue test device and method

Abstract

The present invention provides a suspension bridge main cable steel wire bending friction corrosion fatigue test device and method, the device is composed of a base frame, a constant pressure loading system, a dynamic tension loading monitoring system, and a dynamic torque measurement system; the method is to put the steel wire in a clamp; realize the control of the servo electric cylinder; make the fatigue steel wire in a tensioned state; add a corrosion solution into the corrosion tank; clamp the fatigue steel wire; reset the initial reading; obtain the required constant pressure; changing the constant loading pressure can study the bending friction corrosion fatigue behavior of the steel wire under different contact loads, and record the data of each sensor force in real time until the fatigue steel wire produces observable wear. The beneficial effects are: avoiding the sudden drop in contact load caused by wear in the micro-motion zone of the steel wire during the experiment; simulating the contact state and the corrosion environment, realizing complex coupling conditions, dynamically detecting friction and fatigue load, and evaluating the friction corrosion fatigue life; the operation is simple, the function is complete, and the practicability is strong.

Description

Technical Field

[0001] The invention relates to the technical field of steel wire fatigue testing, and in particular to a device and method for testing bending friction corrosion fatigue of main cable steel wires of a suspension bridge. Background Art

[0002] my country's bridge construction has entered the era of crossing rivers and seas. Multi-tower and multi-span suspension bridges achieve ultra-long span bearing capacity by adding intermediate cable towers on the basis of traditional double-tower suspension bridges. They have the advantages of reducing main cable tension, anchorage scale, main span length and comprehensive cost. A suspension bridge (mainly including main cables, cable towers, anchors, slings and stiffening beams) is a suspension system that uses main cables and slings as stiffening beams to transfer loads to cable towers and anchors. The main cable is the key load-bearing structure of a suspension bridge. At the cable tower position, the cross-sectional profile of the main cable is hexagonal. Each main cable is composed of multiple parallel cable strands, and each cable strand is composed of multiple parallel high-strength galvanized steel wires. Therefore, the service status of the main cable directly affects the load-bearing safety and reliability of the suspension bridge.

[0003] The main cables of large-span multi-tower suspension bridges across rivers and seas are subjected to variable load characteristics of the main cables on both sides of the saddle due to wind loads, dead loads (loads of the bridge deck system, stiffening beams, main cables, slings, etc.) and live loads of vehicles. When the main cables bend and pass through the saddle grooves, the variable loads of the main cables on both sides of the saddles cause bending fatigue stress of the steel wires inside the main cables, dynamic contact loads and relative slip between the bent steel wires and between the bent steel wires and the saddle grooves, that is, bending friction fatigue of the main cable steel wires. At the same time, the atmospheric environment of rivers and seas has the characteristics of high humidity, high salt mist (NaCl, MgCl2, etc.), and easy formation of acid rain, and is easy to form electrolyte corrosion solutions with different salt concentrations and pH values. Electrolyte corrosion solution can invade and stay in the main cable during the installation period (more than 1 year). During the service period of the bridge, due to the lack of wire protection at the main cable saddle, loose sealing of the cable strand inlet and outlet, and wind and rain, the corrosion solution invades and accumulates in the gap of the main cable. Therefore, the main cable of a large-span multi-tower suspension bridge across the river and the sea will be in the electrolyte corrosion solution for a long time. Therefore, the coupling effect of bending friction fatigue of the main cable steel wire and electrolyte corrosion solution can easily cause bending friction corrosion fatigue damage of the main cable steel wire, which in turn causes friction wear, electrochemical corrosion, fatigue crack initiation and expansion, and fracture characteristics of the steel wire under different friction pairs, thereby reducing the effective cross-sectional area and bearing capacity of the main cable, and further affecting the bearing safety of the main cable. For this reason, a bending friction corrosion fatigue test device and method for the main cable steel wire of a suspension bridge are urgently needed to reveal the damage and failure mechanism of the main cable steel wire during the bending friction corrosion fatigue process, which is of great significance to prolonging the service life of the main cable steel wire, improving the safety and reliability of the main cable bearing, and ensuring the service safety of the suspension bridge.

[0004] The test devices related to steel wire friction fatigue include: Chinese patent CN111855163A discloses a test device and method for reciprocating tensile friction wear of steel wire rope, which makes the steel wire rope reciprocate through a winch and a pulley block, and applies axial fatigue stress to the steel wire rope using a weight counterweight. The device cannot achieve friction measurement and electrochemical corrosion during bending fatigue; Chinese patent CN107290234B discloses a test system and method for determining the fatigue life of corroded steel wire, which applies axial fatigue load to the steel wire through the reciprocating motion of a jack, and uses a corrosive solution to pre-corrode the test steel wire for a period of time before the test. The device cannot achieve the simultaneous effects of steel wire bending fatigue and the coupled effects of bending fatigue and electrochemical corrosion; Chinese patent CN104297046B discloses a device and method for monitoring the fretting friction fatigue state of steel wire, which can realize multi-axis fretting fatigue experiments of steel wire under composite motion modes such as pull-pull fatigue, torsion and variable cross angle swing, but cannot realize the application of steel wire bending fatigue and electrochemical corrosion environment; Chinese patent CN101598647B discloses a steel wire fretting fatigue testing machine and method, which can realize steel wire fretting fatigue testing under the coupled effects of fretting wear and axial fatigue stress, but cannot realize the application of steel wire bending fatigue and electrochemical corrosion environment. Summary of the invention

[0005] In order to solve the above problems, especially to address the deficiencies in the prior art, the present invention provides a suspension bridge main cable steel wire bending friction corrosion fatigue test device and method that can comprehensively solve the above problems.

[0006] To achieve the above purpose, the present invention adopts the following technical means:

[0007] A suspension bridge main cable steel wire bending friction corrosion fatigue test device, which is composed of a base frame, a constant pressure loading system, a dynamic tension loading monitoring system, and a dynamic torque measurement system;

[0008] The base frame includes a middle table, the four corners of the middle table steel plate are respectively connected to support columns, the lower part of the support column is connected to a support cross frame, the top of the support cross frame is connected to the lower table, the top of the middle table is connected to the upper table through a support plate, and the upper table is connected to a guide rail mounting plate;

[0009] The constant pressure loading system includes a double steel wire clamp, a pressure sensor adapter plate connected to the double steel wire clamp, a flat pressure sensor connected to the pressure sensor adapter plate, a loading tray connected to the flat pressure sensor, a ball slider connected to the loading tray, and a guide rail connected to the guide rail mounting plate, the front and rear sides of the guide rail mounting plate are respectively connected to a rope pulley frame 1 and a rope pulley frame 3, and the top of the guide rail mounting plate is connected to a rope pulley frame 2;

[0010] The dynamic tension loading monitoring system includes a movable end and a fixed end, wherein the movable end includes a large steering wheel bracket plate 1 fixed on the top of the middle table, a large steering wheel 1 connected to the large steering wheel bracket plate 1, a servo electric cylinder fixed on the top of the lower platform, a coupling connected to the servo electric cylinder, an S-type tension sensor 1 connected to the coupling, and a monofilament clamp 1 connected to the S-type tension sensor 1; the fixed end includes a large steering wheel bracket plate 2 fixed on the top of the middle table, an S-type tension sensor mounting plate and a large steering wheel 2 connected to the large steering wheel bracket plate 2, an S-type tension sensor 2 connected to the S-type tension sensor mounting plate, and a monofilament clamp 2 connected to the S-type tension sensor 2;

[0011] The dynamic torque measurement system includes a saddle plate, a saddle mounting plate connected to the saddle plate, a flange plate 1 connected to the rear end of the saddle mounting plate, a rotating shaft 1 connected to the flange plate 1, a deep groove ball bearing 1 connected to the end of the rotating shaft 1 away from the flange plate 1, a rotating shaft support plate 1 connected to the deep groove ball bearing 1, a flange plate 2 symmetrically installed with the flange plate 1, the rotating shaft 1, the deep groove ball bearing 1, and the rotating shaft support plate 1 about the saddle mounting plate, a rotating shaft 2, a deep groove ball bearing 2 and a rotating shaft support plate 2, a flange plate 3 connected to the end of the rotating shaft 2 away from the flange plate 2, a flange plate 4 connected to the flange plate 3, a thick shaft 1 connected to the flange plate 4, a flange plate 5 connected to the end of the thick shaft 1 away from the flange plate 4, a torque sensor connected to the flange plate 5, a flange plate 6 connected to the end of the torque sensor away from the flange plate 5, a thick shaft 2 connected to the flange plate 6, a flange plate 7 connected to the end of the thick shaft 2 away from the flange plate 6, and a fixed frame connected to the flange plate 7, wherein the rotating shaft support plate 1, the rotating shaft support plate 2 and the fixed frame are all connected to the upper table.

[0012] A further preferred embodiment of the present invention is as follows: the guide rail mounting plate comprises a guide rail mounting fixed plate and a guide rail mounting vertical plate, the guide rail mounting vertical plate is vertically connected to the guide rail mounting fixed plate, the guide rail mounting fixed plate is fastened to the guide rail mounting vertical plate via reinforcing rib three, and the reinforcing rib three is in the shape of a triangular plate.

[0013] A further preferred embodiment of the present invention is as follows: the double steel wire clamp comprises a movable block and a fixed block, the movable block is connected to the fixed block by a fastening bolt, the movable block and the fixed block are both provided with an arc groove matching the bending curvature and diameter of the steel wire, and the radius of the arc groove is slightly smaller than the radius of the steel wire.

[0014] A further preferred solution of the present invention is that the loading tray is L-shaped, and threaded holes are respectively provided at the four corners on the top of the loading tray, and the threaded holes are connected with eye nuts.

[0015] A further preferred embodiment of the present invention is as follows: the rope pulley frame 1 comprises a pulley mounting base plate 1 connected to the guide rail mounting plate, the pulley mounting base plate 1 is connected to a pulley mounting block 1 through a pulley support frame 1, and the pulley mounting block 1 is rotatably connected to a pulley 1;

[0016] The rope pulley frame 2 includes a pulley mounting base plate 2 connected to the guide rail mounting plate, the pulley mounting base plate 2 is connected to a pulley mounting block 2 through a pulley support frame 2, and the pulley mounting block 2 is rotatably connected to a pulley 2;

[0017] The rope pulley frame three includes a pulley mounting base plate three connected to the guide rail mounting plate, the pulley mounting base plate three is connected to a pulley mounting block three through a pulley support frame three, and the pulley mounting block three is rotatably connected to a pulley three.

[0018] A further preferred embodiment of the present invention is as follows: the large steering wheel 1 and the large steering wheel 2 are installed symmetrically in space about the vertical center line of the saddle groove and are located on the same horizontal plane; the large steering wheel bracket plate 2 and the large steering wheel bracket plate 1 are both connected to the middle table surface through a triangular reinforcement rib 1.

[0019] A further preferred embodiment of the present invention is as follows: the structure of the single wire clamp 1 is the same as that of the single wire clamp 2, the single wire clamp 1 comprises a fixed block and a movable block connected to the fixed block, and the bottom end of the fixed block is connected to the S-shaped tension sensor via an external thread.

[0020] A further preferred solution of the present invention is that the upper half of the saddle plate is an arc-shaped plate, and the wrap angle of the saddle plate is the same as the wrap angle of the saddle of the suspension bridge tower.

[0021] A further preferred embodiment of the present invention: the axes of the rotating shaft 1, rotating shaft 2, thick shaft 1, thick shaft 2, deep groove ball bearing 1, deep groove ball bearing 2, flange 1, flange 2, flange 3, flange 4, flange 5, flange 6 and flange 7 are all on the same horizontal line with the center positions of the arcs and wrap angles on the saddle plate.

[0022] A method for testing bending friction corrosion fatigue of main cable steel wires of a suspension bridge, the specific method is as follows:

[0023] a. Use a support rod to prop up the constant pressure loading system at the bottom of the pressure sensor adapter plate, place two sections of steel wire that are slightly longer than the arc length of the double steel wire clamp in the arc groove of the double steel wire clamp in turn, tighten the fastening screws of the double steel wire clamp, and use pointed pliers to bend the excess steel wire at both ends of the double steel wire clamp upwards;

[0024] b. Turn on the power supply of the servo electric cylinder and the frequency converter, connect the frequency converter through the servo controller to control the servo electric cylinder, use the servo controller to adjust the number of pulses, so that the telescopic rod of the electric cylinder moves upward for a certain distance, and stop the displacement action of the electric cylinder;

[0025] c. Fix one end of the fatigue steel wire on the single wire clamp 2, pass the other end of the fatigue steel wire through the large steering wheel 2, the saddle groove on the saddle groove plate, and the large steering wheel 1 in sequence, and fix it on the single wire clamp 1; use the servo controller to adjust the number of pulses to make the telescopic rod of the servo electric cylinder move downward for a certain distance until the fatigue steel wire is in a tensioned state, and then stop the displacement action of the electric cylinder;

[0026] d. Install the corrosion trough on the saddle plate, fill the gaps between the corrosion trough, the saddle plate and the fatigue steel wire with waterproof glue, wait for the waterproof glue to solidify and play a waterproof role, and add the corrosion solution into the corrosion trough;

[0027] e. Remove the support rod at the bottom of the pressure sensor adapter plate. During the removal process, hold the constant pressure loading system with your hands, slowly lower the constant pressure loading system, and place the fatigue steel wire of the saddle groove arc section directly below the middle position of the two curved parallel steel wires clamped by the upper double steel wire clamp;

[0028] f. Turn on the power of the flat pressure sensor, torque sensor, S-type tension sensor 1, and S-type tension sensor 2, connect each sensor to the acquisition card and host computer software, and clear the initial reading of the sensor;

[0029] g. Consider the deadweight of the constant pressure loading device. If the deadweight of the constant pressure loading device is greater than the required constant pressure, use wire ropes to connect the eye nuts at the four corners of the loading tray in sequence, and pass the wire ropes through the first, second, and third sheave frames. Hang a counterweight at the end of the wire rope to offset the deadweight of the constant pressure loading system. If the deadweight of the constant pressure loading system is less than the required constant pressure, place weights of appropriate weight on the loading tray. Through the above operations, the required constant pressure can be obtained.

[0030] h. Change the frequency and forward and reverse rotation of the servo motor to control the speed, position and direction of the telescopic rod of the electric cylinder. The constant loading pressure is measured by a flat pressure sensor, the torque generated by the friction between the fatigue steel wire and the saddle groove is measured by a torque sensor, and the tension at the movable end and the fixed end of the fatigue steel wire is measured by S-type tension sensor 1 and S-type tension sensor 2. The total friction between the fatigue steel wire and the bending parallel loading steel wire and the fatigue steel wire and the saddle groove is obtained by the tension difference of the two S-type tension sensors. The subsequent data processing of the tension difference of the S-type tension sensor and the torque value of the torque sensor can obtain the friction between the fatigue steel wire and the loading steel wire, and between the fatigue steel wire and the saddle groove. Changing the constant loading pressure can study the bending friction corrosion fatigue behavior of the steel wire under different contact loads, and record the data of each sensor force in real time until the fatigue steel wire produces observable wear.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention adopts a loading method of ball slider guide, placing weights on the loading tray and hanging a fixed load on the rope rack wheel. It can apply a constant contact load between steel wires. Under the action of gravity, the loaded steel wire and the fatigue steel wire always maintain contact, avoiding the sudden drop of contact load caused by wear in the micro-motion zone of the steel wire during the experiment; it can simulate the bending contact state and corrosion environment of the high-strength galvanized steel wire inside the main cable at the saddle, realize the complex coupling conditions of bending fatigue, friction wear and corrosion environment, dynamically detect the direct friction force and fatigue load between the steel wire and the saddle groove pair during the bending friction corrosion fatigue process, and can quantitatively evaluate the friction wear evolution, fatigue fracture characteristics and bending friction corrosion fatigue life of the bending steel wire; the device is easy to operate and fully functional, and has strong practicality for studying the bending corrosion fatigue behavior of the main cable steel wire at the saddle. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a front view of the structure of the present invention;

[0034] Figure 2 The structure of the present invention Figure 1 Left view of part I;

[0035] Figure 3 It is a front view of the saddle plate and the saddle mounting plate of the present invention;

[0036] Figure 4 is a schematic diagram of a monofilament clamp of the present invention;

[0037] Figure 5 It is a front view, a cross-sectional view and a partial enlarged view of the double steel wire clamp of the present invention;

[0038] Figure 6 It is a schematic diagram of the split type etching tank of the present invention;

[0039] In the figure:

[0040] 1. Support column; 2. Support cross frame; 3. Middle table; 4. Large steering wheel bracket plate 2; 5. S-type tension sensor mounting plate; 6. Reinforcement rib 1; 7. S-type tension sensor 2; 8. Monofilament clamp 2; 9. Large steering wheel 2; 10. Reinforcement rib 2; 11. Support plate; 12. Upper table; 13. Fatigue steel wire; 14. Large steering wheel 1; 15. Monofilament clamp 1; 16. S-type tension sensor 1; 17. Large steering wheel bracket Plate 1; 18, coupling; 19, servo electric cylinder; 20, lower table; 21, guide rail mounting plate; 22, deep groove ball bearing 1; 23, reinforcing rib 3; 24, rotating shaft 1; 25, guide rail mounting vertical plate; 26, double wire clamp movable block; 27, double wire clamp fixed block; 28, pressure sensor adapter plate; 29, flat pressure sensor; 30, lifting eye nut; 31, loading tray; 32, slider; 33, slide 1. Pulley mounting base plate 3; 2. Pulley support frame 3; 3. Pulley mounting block 3; 3. Pulley 3; 3. Pulley mounting base plate 2; 3. Pulley support frame 2; 3. Pulley mounting block 2; 4. Pulley 2; 4. Pulley mounting base plate 1; 4. Pulley support frame 1; 4. Pulley mounting block 1; 4. Pulley 1; 4. Guide rail; 4. Saddle plate; 4. Corrosion groove; 4. Rotating shaft 2; 4. Flange plate 3; 5. 0. Flange four; 51. Thick shaft one; 52. Flange five; 53. Thick shaft two; 54. Reinforcing rib four; 55. Fixed frame; 56. Flange seven; 57. Flange six; 58. Torque sensor; 59. Deep groove ball bearing two; 60. Rotating shaft support plate two; 61. Flange two; 62. Saddle groove mounting plate; 63. Flange one; 64. Rotating shaft support plate one; 65. Movable block of monofilament clamp; 66. Fixed block of monofilament clamp. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings:

[0042] As attached Figure 1 -Attached Figure 6 As shown, a suspension bridge main cable steel wire bending friction corrosion fatigue test device is mainly composed of a base frame, a constant pressure loading system, a dynamic tension loading monitoring system, and a dynamic torque measurement system.

[0043] The base frame is mainly divided into three levels: an upper table 12, a middle table 3 and a lower table 20, including four support columns 1 symmetrically arranged at the four corners of the steel plate of the middle table 3, a support cross frame 2 symmetrically arranged at the lower part of the support column 1, a lower table 20 connected to the support cross frame 2 through a threaded key, a support plate 11 and a second reinforcing rib 10 symmetrically arranged on the middle table 3, an upper table 12 connected to the upper part of the support plate 11 through a threaded key, and a guide rail mounting plate and a third reinforcing rib 23 arranged on the upper table 12; the lower table 20 is used to install a servo electric cylinder 19, and four threaded holes are opened on the lower table 20 for connecting the servo electric cylinder 19 with the lower table 20; the middle table 3 has a rectangular notch on the upper part of the servo electric cylinder 19 to ensure that the servo electric cylinder shaft 19 can smoothly extend out of the middle table 3;

[0044] The guide rail mounting plate includes a guide rail mounting fixed plate 21 and a guide rail mounting vertical plate 25. The guide rail mounting vertical plate 25 is fixed to the guide rail mounting fixed plate 21 by a threaded key, and a reinforcing rib three 23 is added to make the structure firm; the reinforcing rib three 23 is in the shape of a triangular plate, and the reinforcing rib ensures the reliability and verticality of the structure.

[0045] The constant pressure loading system includes a double steel wire clamp, a pressure sensor adapter plate 28 connected to the double steel wire clamp by threads, a flat pressure sensor 29 connected to the pressure sensor adapter plate 28 by threads, a loading tray 31 connected to the flat pressure sensor 29 by threads, and a ball slider 32 connected to the loading tray 31 by threads. The ball slider 32 and the guide rail 45 installed on the guide rail mounting plate form a moving pair, the first and third pulley frames are symmetrically installed on the front and rear surfaces of the upper end of the guide rail mounting plate, and the second pulley frame is centrally installed on the top of the guide rail mounting plate.

[0046] The double steel wire clamp comprises a fixed block 27 and a movable block 26. Both the fixed block 27 and the movable block 26 have arc grooves matching the bending curvature and diameter of the steel wire. The radius of the arc groove is slightly smaller than the radius of the steel wire. After the two sections of steel wire are bent and placed in parallel in the groove, the fastening bolts between the fixed block 27 and the movable block 26 are tightened to clamp the bent parallel steel wires. Part of the arc surface of the two sections of loaded steel wires is exposed at the bottom of the double steel wire clamp as a direct contact part with the fatigue steel wire.

[0047] The loading tray 31 is L-shaped, and the L-shaped loading tray 31 is reinforced by reinforcing ribs on the left and right sides to ensure the verticality between the vertical plate and the horizontal plate. A total of four threaded holes are symmetrically provided at the four corners of the top of the loading tray 31. The eye nuts 30 can be tightened at the corresponding threaded holes. The four eye nuts 30 are connected by nylon ropes and passed through the first, second and third rope pulley frames in sequence. A heavy object is hung at the other end of the nylon rope to offset the deadweight of the constant pressure loading system.

[0048] The guide rail 45 is composed of two sections of guide rails that are symmetrical with respect to the middle surface of the guide rail mounting plate, are equal in length, and are parallel to each other. There is a ball slider 32 on each of the two sections of the guide rails. The rope pulley frame 1 includes a pulley mounting base plate 141 connected to the guide rail mounting plate. The pulley mounting base plate 141 is connected to a pulley mounting block 143 through a pulley support frame 142. The pulley mounting block 143 is rotatably connected to a pulley 144.

[0049] The rope pulley frame 2 includes a pulley mounting base plate 2 37 connected to the guide rail mounting plate, the pulley mounting base plate 2 37 is connected to a pulley mounting block 2 39 through a pulley support frame 2 38, and the pulley mounting block 2 39 is rotatably connected to a pulley 2 40;

[0050] The rope pulley frame three includes a pulley mounting base plate three 33 connected to the guide rail mounting plate, the pulley mounting base plate three 33 is connected to a pulley mounting block three 35 through a pulley support frame three 34, and the pulley mounting block three 35 is rotatably connected to a pulley three 36.

[0051] The dynamic tension loading monitoring system is generally divided into a movable end and a fixed end, wherein the movable end includes a servo electric cylinder 19 fixed to the lower platform 20 of the base frame, a coupling 18 threadedly connected to the servo electric cylinder shaft, an S-type tension sensor 16 connected to the coupling 18, and a single wire clamp 15 connected to the S-type tension sensor 16; the fixed end includes a single wire clamp 28, an S-type tension sensor 27 threadedly connected to the single wire clamp 28, an S-type tension sensor mounting plate 5 threadedly connected to the S-type tension sensor 27, and a large steering wheel bracket plate 24 threadedly connected to the S-type tension sensor mounting plate 5;

[0052] The fatigue steel wire is connected with the single wire clamp 15, the large steering wheel 14, the saddle plate 46, the large steering wheel 29, and the single wire clamp 28 in sequence;

[0053] The large steering wheel 14 and the large steering wheel 2 9 are installed symmetrically in space about the vertical center line of the saddle groove and are on the same horizontal plane. The large steering wheel 14 and the large steering wheel 2 9 are connected to the large steering wheel bracket plate 17 and the large steering wheel bracket plate 2 4 respectively through threaded keys; the large steering wheel bracket plate 17 and the large steering wheel bracket plate 2 4 are both equipped with triangular reinforcing ribs 1 6, which ensure the verticality of the large steering wheel bracket plate and enhance the reliability of the structure;

[0054] The coupling 18 is made of bar stock, the internal thread of the coupling 18 is threadedly connected with the external thread shaft on the electric cylinder 19, and the upper end of the coupling 18 is processed into an external thread that matches the S-type tension sensor 16;

[0055] The single wire clamp 15 and the single wire clamp 2 8 have the same structure. The single wire clamp consists of a fixed block 66 and a movable block 65. The bottom end of the fixed block 66 is connected to the S-type tension sensor 16 through an external thread. A total of four threaded holes are symmetrically opened on the upper half of the plate of the fixed block 66 about the axis, and a semi-cylindrical groove with a diameter slightly smaller than the diameter of the fatigue steel wire is opened along the axial direction. A through hole and a semi-cylindrical groove corresponding to the thread position of the fixed block 66 are opened on the movable block 65. There is a through hole for the excess steel wire to pass through on the center line of the lower part of the movable block 65. In the longitudinal position, the through hole for the excess steel wire to pass through is lower than the remaining holes; when the fatigue steel wire is in a tensioned state, the direction of the fatigue steel wire from the single wire clamp to the large steering wheel section should be perpendicular to the working table of the base frame, and at the same time, the fatigue steel wire from the saddle groove to the large steering wheel section should form a natural and smooth transition with the saddle groove to conform to the wrap angle of the saddle groove plate 46 and reduce the friction and wear of the non-working part of the fatigue steel wire during operation.

[0056] The dynamic torque measurement system includes a saddle plate 46, a saddle mounting plate 62 connected to the saddle plate 46, a flange 63 connected to the rear end of the saddle mounting plate 62 by threads, a rotating shaft 24 connected to the flange 63, a deep groove ball bearing 22 connected to the end of the rotating shaft 24 away from the flange 63, a rotating shaft support plate 64 connected to the deep groove ball bearing 22 by interference fit, a flange 61 symmetrically installed with the flange 63, the rotating shaft 24, the deep groove ball bearing 22, and the rotating shaft support plate 64 about the saddle mounting plate 62, a rotating shaft 48, a deep groove ball bearing 59, and a rotating shaft support plate 64. Plate 2 60, flange 3 49 connected to the end of rotating shaft 2 48 away from flange 2 61, flange 4 50 connected to flange 3 49 by thread, thick shaft 1 51 connected to flange 4 50, flange 5 52 connected to the end of thick shaft 1 51 away from flange 4 50, torque sensor 58 connected to flange 5 52 by thread, flange 6 57 connected to the end of torque sensor 58 away from flange 5 52 by thread, thick shaft 2 53 connected to flange 6 57, flange 7 56 connected to the end of thick shaft 2 53 away from flange 6 57, and fixing frame 55 connected to flange 7 56 by thread;

[0057] The upper half of the saddle groove plate 46 is an arc-shaped plate, and the wrap angle of the saddle groove plate 46 is the same as the wrap angle of the cable saddle of the suspension bridge tower. The left and right sides of the bottom of the saddle groove plate 46 are ear-shaped. There are four threaded holes symmetrical about the vertical plane of the saddle groove plate 46 on the left and right ear plates. Four threaded holes are symmetrically opened on the front and rear surfaces of the saddle groove plate 46. The four threaded holes are on the same horizontal plane. In the steel wire fatigue corrosion test, screws can be screwed on the threaded holes, and the corrosion groove 47 is installed on the screws. The screws play a role in positioning and supporting the corrosion groove 47.

[0058] The corrosion groove 47 is composed of two components with the same structure. A groove of a suitable size is opened at the bottom of a single component. After the two components of the corrosion groove 47 are fastened together by bolt connection, the size of the rectangular groove at the bottom of the connected corrosion groove 47 is adapted to the rectangular size of the saddle groove plate 46. There are grooves on the left and right sides of the corrosion groove 47 for the fatigue steel wire to pass through. The grooves ensure that the fatigue steel wire and the corrosion groove 47 do not interfere with each other during the experiment.

[0059] The saddle groove mounting plate 62 has ear plates at the left and right ends of the upper half, and the left and right ear plates have four through holes corresponding to the positions of the threaded holes on the left and right ear plates of the saddle groove plate 46. The saddle groove plate 46 and the saddle groove mounting plate 62 are connected by threads, and the saddle groove part is prone to wear and failure. Making the saddle groove plate 46 and the saddle groove mounting plate 62 into a split type is conducive to replacing the saddle groove plate 46 that has worn and failed in subsequent fatigue experiments; in terms of space, the center of the circle corresponding to the arc of the saddle groove on the saddle groove plate 46 exists on the saddle groove mounting plate 62, and the distance L from any point on the saddle groove to the center of the circle is the size of the force arm in the torque calculation. Four threaded holes are opened on the saddle groove mounting plate 62 and are evenly distributed in a circle with the center position, and the distance from the threaded hole to the center position should match the position and size of the through holes on the flanges 1 63 and 2 61;

[0060] The axes of the rotating shaft 1 24, the rotating shaft 2 48, the thick shaft 1 51, the thick shaft 2 53, the deep groove ball bearing 1 22, the deep groove ball bearing 2 59, the flange 1 63, the flange 2 61, the flange 3 49, the flange 4 50, the flange 5 52, the flange 6 57, and the flange 7 56 are all on the same horizontal line as the center positions of the arcs and the wrap angles on the saddle plate 46;

[0061] The rotating shaft support plate is a T-shaped plate, which is connected to the upper table 12 of the base frame through threads;

[0062] The fixing frame 55 is fixed by a triangular reinforcing rib 54 to ensure verticality and enhance structural reliability. The fixing frame 55 is fixed to the upper table 12 of the base frame by threaded connection;

[0063] During the fatigue test, the micro-motion fatigue steel wire and the saddle groove are in surface contact and there is friction, and the friction is finally transmitted to the torque sensor 58 through the saddle groove plate 46, the saddle groove plate mounting frame, and the rotating shaft; in the torque transmission assembly, one end of the torque sensor 58 is supported by a rotatable shaft and a deep groove ball bearing to achieve torque transmission, and the other end is connected to the fixed frame 55 for fixation, thereby achieving torque transmission and measurement. The friction between the fatigue steel wire and the saddle groove is obtained from the measurement data of the torque sensor 58 and the known size L of the fixed force arm, thereby achieving indirect measurement of the friction between the fatigue steel wire and the saddle groove by the torque sensor 58.

[0064] A method for testing bending friction corrosion fatigue of main cable steel wires of a suspension bridge, the specific method is as follows:

[0065] a. Use a support rod to support the bottom of the pressure sensor adapter plate 28 to prop up the constant pressure loading system, place two sections of steel wire slightly longer than the arc length of the double wire clamp in the arc groove of the double wire clamp in turn, tighten the fastening screws of the double wire clamp, and use a pointed pliers to bend the excess steel wire at both ends of the double wire clamp upward;

[0066] b. Turn on the servo electric cylinder 19 and the inverter power supply, connect the inverter through the servo controller to control the servo electric cylinder 19, adjust the number of pulses with the servo controller, so that the telescopic rod of the electric cylinder 19 moves upward for a period of time, and stop the displacement action of the electric cylinder 19;

[0067] c. Fix one end of the fatigue steel wire on the single wire clamp 2 8, pass the other end of the fatigue steel wire through the large steering wheel 2 9, the saddle groove on the saddle groove plate 46, the large steering wheel 14 in sequence, and fix it on the single wire clamp 15; use the servo controller to adjust the number of pulses so that the telescopic rod of the servo electric cylinder 19 moves downward for a certain distance until the fatigue steel wire is in a tensioned state, and stop the displacement action of the electric cylinder 19;

[0068] d. The corrosion groove 47 is installed on the saddle groove plate 46, and the corrosion groove 47 and the saddle groove plate 46 are filled with waterproof glue, and the gap between the fatigue wire is filled, and the waterproof glue is solidified to play a waterproof role, and the corrosion solution is added to the corrosion groove 47;

[0069] e. Remove the support rod supported at the bottom of the pressure sensor adapter plate 28, hold the constant pressure loading system by hand during the removal process, slowly lower the constant pressure loading system, and place the fatigue wire of the saddle groove arc segment directly below the middle position of the two curved parallel wires clamped by the upper double wire clamp;

[0070] f. Turn on the power of the flat-plate pressure sensor 29, torque sensor 58, S-type tension sensor 16, S-type tension sensor 2 7, connect each sensor to the acquisition card, host computer software and reset the initial reading of the sensor;

[0071] g. Consider the deadweight of the constant pressure loading device. If the deadweight of the constant pressure loading device is greater than the required constant pressure, use wire ropes to connect the eye nuts at the four corners of the loading tray in sequence, and pass the wire ropes through the first, second, and third sheave frames. Hang a counterweight at the end of the wire rope to offset the deadweight of the constant pressure loading system. If the deadweight of the constant pressure loading system is less than the required constant pressure, place a weight of appropriate weight on the loading tray. Through the above operations, the required constant pressure can be obtained.

[0072] h. Change the frequency and forward and reverse rotation of the servo motor to control the speed, position and direction of the telescopic rod of the electric cylinder. The constant loading pressure is measured by a flat pressure sensor, the torque generated by the friction between the fatigue steel wire and the saddle groove is measured by a torque sensor, and the tension of the movable end and the fixed end of the fatigue steel wire is measured by S-type tension sensor 1 and S-type tension sensor 2. The total friction between the fatigue steel wire and the bending parallel loading steel wire and the fatigue steel wire and the saddle groove is obtained by the tension difference of the two S-type tension sensors. The friction between the fatigue steel wire and the loading steel wire and between the fatigue steel wire and the saddle groove can be obtained by subsequent data processing of the tension difference of the S-type tension sensor and the torque value of the torque sensor. The friction between the fatigue steel wire and the loading steel wire and between the fatigue steel wire and the saddle groove can be obtained. Changing the constant loading pressure can study the bending friction corrosion fatigue behavior of the steel wire under different contact loads, and the data of each sensor force can be recorded in real time until the fatigue steel wire produces observable wear.

[0073] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0074] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. 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. A method for testing bending friction corrosion fatigue of main cable steel wires of a suspension bridge, characterized in that: The test device adopts the bending friction corrosion fatigue test device of the main cable wire of the suspension bridge, which is composed of a base frame, a constant pressure loading system, a dynamic tension loading monitoring system, and a dynamic torque measurement system; The base frame includes a middle table, the four corners of the middle table steel plate are respectively connected to support columns, the lower part of the support column is connected to a support cross frame, the top of the support cross frame is connected to the lower table, the top of the middle table is connected to the upper table through a support plate, and the upper table is connected to a guide rail mounting plate; The constant pressure loading system includes a double steel wire clamp, a pressure sensor adapter plate connected to the double steel wire clamp, a flat pressure sensor connected to the pressure sensor adapter plate, a loading tray connected to the flat pressure sensor, a ball slider connected to the loading tray, and a guide rail connected to the guide rail mounting plate, the front and rear sides of the guide rail mounting plate are respectively connected to a rope pulley frame 1 and a rope pulley frame 3, and the top of the guide rail mounting plate is connected to a rope pulley frame 2; The dynamic tension loading monitoring system includes a movable end and a fixed end, wherein the movable end includes a large steering wheel bracket plate 1 fixed on the top of the middle table, a large steering wheel 1 connected to the large steering wheel bracket plate 1, a servo electric cylinder fixed on the top of the lower platform, a coupling connected to the servo electric cylinder, an S-type tension sensor 1 connected to the coupling, and a monofilament clamp 1 connected to the S-type tension sensor 1; the fixed end includes a large steering wheel bracket plate 2 fixed on the top of the middle table, an S-type tension sensor mounting plate and a large steering wheel 2 connected to the large steering wheel bracket plate 2, an S-type tension sensor 2 connected to the S-type tension sensor mounting plate, and a monofilament clamp 2 connected to the S-type tension sensor 2; The dynamic torque measurement system comprises a saddle plate, a saddle mounting plate connected to the saddle plate, a flange plate 1 connected to the rear end of the saddle mounting plate, a rotating shaft 1 connected to the flange plate 1, a deep groove ball bearing 1 connected to the end of the rotating shaft 1 away from the flange plate 1, a rotating shaft support plate 1 connected to the deep groove ball bearing 1, a flange plate 2 symmetrically installed with the flange plate 1, the rotating shaft 1, the deep groove ball bearing 1, and the rotating shaft support plate 1 about the saddle mounting plate, a rotating shaft 2, a deep groove ball bearing 2 and a rotating shaft support plate 2, a flange plate 3 connected to the end of the rotating shaft 2 away from the flange plate 2, a flange plate 4 connected to the flange plate 3, a thick shaft 1 connected to the flange plate 4, a flange plate 5 connected to the end of the thick shaft 1 away from the flange plate 4, a torque sensor connected to the flange plate 5, a flange plate 6 connected to the end of the torque sensor away from the flange plate 5, a thick shaft 2 connected to the flange plate 6, a flange plate 7 connected to the end of the thick shaft 2 away from the flange plate 6, and a fixed frame connected to the flange plate 7, wherein the rotating shaft support plate 1, the rotating shaft support plate 2 and the fixed frame are all connected to the upper table surface; The specific method is as follows: a. Use a support rod to prop up the constant pressure loading system at the bottom of the pressure sensor adapter plate, place two sections of steel wire that are slightly longer than the arc length of the double steel wire clamp in the arc groove of the double steel wire clamp in turn, tighten the fastening screws of the double steel wire clamp, and use pointed pliers to bend the excess steel wire at both ends of the double steel wire clamp upwards; b. Turn on the power supply of the servo electric cylinder and the frequency converter, connect the frequency converter through the servo controller to control the servo electric cylinder, use the servo controller to adjust the number of pulses, so that the telescopic rod of the electric cylinder moves upward for a certain distance, and stop the displacement action of the electric cylinder; c. Fix one end of the fatigue steel wire on the single wire clamp 2, pass the other end of the fatigue steel wire through the large steering wheel 2, the saddle groove on the saddle groove plate, and the large steering wheel 1 in sequence, and fix it on the single wire clamp 1; use the servo controller to adjust the number of pulses to make the telescopic rod of the servo electric cylinder move downward for a certain distance until the fatigue steel wire is in a tensioned state, and then stop the displacement action of the electric cylinder; d. Install the corrosion trough on the saddle plate, fill the gaps between the corrosion trough, the saddle plate and the fatigue steel wire with waterproof glue, wait for the waterproof glue to solidify and play a waterproof role, and add the corrosion solution into the corrosion trough; e. Remove the support rod at the bottom of the pressure sensor adapter plate. During the removal process, hold the constant pressure loading system with your hands, slowly lower the constant pressure loading system, and place the fatigue steel wire of the saddle groove arc section directly below the middle position of the two curved parallel steel wires clamped by the upper double steel wire clamp; f. Turn on the power of the flat pressure sensor, torque sensor, S-type tension sensor 1, and S-type tension sensor 2, connect each sensor to the acquisition card and host computer software, and clear the initial reading of the sensor; g. Consider the deadweight of the constant pressure loading device. If the deadweight of the constant pressure loading device is greater than the required constant pressure, use wire ropes to connect the eye nuts at the four corners of the loading tray in sequence, and pass the wire ropes through the first, second, and third sheave frames. Hang a counterweight at the end of the wire rope to offset the deadweight of the constant pressure loading system. If the deadweight of the constant pressure loading system is less than the required constant pressure, place weights of appropriate weight on the loading tray. Through the above operations, the required constant pressure can be obtained. h. Change the frequency and forward and reverse rotation of the servo motor to control the speed, position and direction of the telescopic rod of the electric cylinder. The constant loading pressure is measured by a flat pressure sensor, the torque generated by the friction between the fatigue steel wire and the saddle groove is measured by a torque sensor, and the tension at the movable end and the fixed end of the fatigue steel wire is measured by S-type tension sensor 1 and S-type tension sensor 2. The total friction between the fatigue steel wire and the bending parallel loading steel wire and the fatigue steel wire and the saddle groove is obtained by the tension difference of the two S-type tension sensors. The subsequent data processing of the tension difference of the S-type tension sensor and the torque value of the torque sensor can obtain the friction between the fatigue steel wire and the loading steel wire, and between the fatigue steel wire and the saddle groove. Changing the constant loading pressure can study the bending friction corrosion fatigue behavior of the steel wire under different contact loads, and record the data of each sensor force in real time until the fatigue steel wire produces observable wear.

2. A suspension bridge main cable steel wire bending friction corrosion fatigue test method according to claim 1, characterized in that: The guide rail mounting plate includes a guide rail mounting fixed plate and a guide rail mounting vertical plate, the guide rail mounting vertical plate is vertically connected to the guide rail mounting fixed plate, the guide rail mounting fixed plate is fastened to the guide rail mounting vertical plate through a reinforcing rib three, and the reinforcing rib three is in the shape of a triangular plate.

3. The bending friction corrosion fatigue test method of the main cable steel wire of a suspension bridge according to claim 1 is characterized in that: The double steel wire clamp comprises a movable block and a fixed block, wherein the movable block is connected to the fixed block by a fastening bolt, and both the movable block and the fixed block are provided with an arc groove matching the bending curvature and diameter of the steel wire, and the radius of the arc groove is slightly smaller than the radius of the steel wire.

4. The bending friction corrosion fatigue test method for main cable steel wire of a suspension bridge according to claim 1 is characterized in that: The loading tray is L-shaped, and threaded holes are respectively opened at the four corners of the top of the loading tray, and the threaded holes are connected with eye nuts.

5. The bending friction corrosion fatigue test method of the main cable steel wire of a suspension bridge according to claim 1 is characterized in that: The rope pulley frame 1 includes a pulley mounting base plate 1 connected to the guide rail mounting plate, the pulley mounting base plate 1 is connected to a pulley mounting block 1 through a pulley support frame 1, and the pulley mounting block 1 is rotatably connected to a pulley 1; The rope pulley frame 2 includes a pulley mounting base plate 2 connected to the guide rail mounting plate, the pulley mounting base plate 2 is connected to a pulley mounting block 2 through a pulley support frame 2, and the pulley mounting block 2 is rotatably connected to a pulley 2; The rope pulley frame three includes a pulley mounting base plate three connected to the guide rail mounting plate, the pulley mounting base plate three is connected to a pulley mounting block three through a pulley support frame three, and the pulley mounting block three is rotatably connected to a pulley three.

6. A suspension bridge main cable steel wire bending friction corrosion fatigue test method according to claim 1, characterized in that: The large steering wheel 1 and the large steering wheel 2 are installed symmetrically in space about the vertical center line of the saddle groove and are on the same horizontal plane; the large steering wheel bracket plate 2 and the large steering wheel bracket plate 1 are both connected to the middle table surface through a triangular reinforcement rib 1.

7. A suspension bridge main cable steel wire bending friction corrosion fatigue test method according to claim 1, characterized in that: The structure of the single wire clamp 1 is the same as that of the single wire clamp 2. The single wire clamp 1 includes a fixed block and a movable block connected to the fixed block. The bottom end of the fixed block is connected to the S-shaped tension sensor through an external thread.

8. The method for testing bending friction corrosion fatigue of main cable steel wires of a suspension bridge according to claim 1, characterized in that: The upper part of the saddle plate is an arc-shaped plate, and the wrap angle of the saddle plate is the same as the wrap angle of the saddle of the cable tower of the suspension bridge.

9. A suspension bridge main cable steel wire bending friction corrosion fatigue test method according to claim 8, characterized in that: The axes of the rotating shaft 1, rotating shaft 2, thick shaft 1, thick shaft 2, deep groove ball bearing 1, deep groove ball bearing 2, flange 1, flange 2, flange 3, flange 4, flange 5, flange 6 and flange 7 are all on the same horizontal line with the center positions of the arcs and wrap angles on the saddle plate.

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