Tension, bending and torsion friction corrosion fatigue test device and method for straddle type sling of suspension bridge

Abstract

The invention belongs to the technical field of suspension bridge sling tests, and discloses a suspension bridge straddle type sling tension-bending-torsion friction corrosion fatigue test device and method, and the device comprises a rack module, a driving module, an environment simulation module and a data acquisition and processing module. The rack module comprises a plurality of supporting stand columns, a middle cross beam, a supporting platform, two vertical beams, a top cross beam and a rack top plate. The driving module comprises a servo controller, a servo electric cylinder and a heavy load rotary table; the driving module further comprises a ball screw mechanism and a sling groove, the sling groove is sleeved with the middle of the sling, and the data collecting and processing module comprises a first tension sensor, a second tension sensor, a first high-speed camera, a second high-speed camera and a third high-speed camera. Through cooperation of multiple modules, the functions of fatigue loading, bending simulation, torsion application, corrosion environment simulation and the like are integrated, and the multi-factor coupling effect of tension, bending, torsion, friction, corrosion and fatigue is accurately reproduced.

Description

Technical Field

[0001] This invention relates to the field of suspension bridge cable testing technology, and in particular to a device and method for testing the tensile, bending, torsional, frictional, corrosion, and fatigue of suspension bridge straddle cables. Background Technology

[0002] Suspension bridges are one of the mainstream configurations for long-span bridges. As the core force-transferring component, the suspenders bear the crucial function of stably transferring the bridge deck load to the main cable. Their structural safety during service directly determines the long-term reliability and operational safety of the overall suspension bridge structure. Overhead suspenders, with their significant advantages such as compact structural layout, strong spatial adaptability, and optimized force transmission path, are increasingly widely used in modern suspension bridge projects, such as long-span sea / river suspension bridges, where there are special requirements for structural space and appearance. However, due to their unique structural form, the complexity of their service environment and the special nature of their stress state are fundamentally different from traditional ordinary straight suspenders.

[0003] The core structural feature of straddle-type suspenders is that the suspender forms a specific straddle contact section at the contact points with cable clamps, bogies, or bridge deck connectors. This contact section is not subjected to a simple linear stress mode but is under constant bending deformation, resulting in a significant stress concentration effect in the contact area. Simultaneously, bridge deck vibration, alternating temperature changes causing thermal expansion and contraction displacement of the suspender, and dynamic load excitation from vehicle movement drive continuous fretting wear between the suspender and the contact components, causing wear damage to the suspender contact surface. Furthermore, the service environment of suspenders is often accompanied by harsh corrosive media. Environmental factors such as chloride ions in the marine atmosphere and high humidity and rainfall exert a continuous corrosive effect on the suspenders. Combined with the repeated dynamic loads throughout the bridge's lifespan, straddle-type suspenders actually endure a multi-field coupled effect of "bending-friction-corrosion fatigue." This coupling effect significantly accelerates the surface damage evolution, microcrack initiation, and propagation process of the suspender wires through frictional damage to the protective layer, accelerated corrosion intrusion, increased stress concentration due to bending, and fatigue-promoted crack propagation. Ultimately, this leads to premature failure of the suspender, causing bridge structural safety accidents and threatening public transportation safety. Therefore, there is an urgent need for a bending friction fatigue testing device for hoisting wire ropes of deep-sea drilling rigs, which can be used to reveal the evolution law of bending friction fatigue damage of wire ropes under different friction pairs (between wire ropes, wire rope-drum groove, wire rope-drum partition, wire rope-pulley groove), which is of great significance to ensuring the safe and reliable service of the hoisting system of deep-sea drilling rigs.

[0004] Regarding experimental devices for cable friction fatigue testing, Chinese invention patent CN118961393B, entitled "A Cable Tension-Bending Fatigue Testing Device," discloses a cable tension-bending fatigue testing device that can simultaneously perform axial tension and bending of the cable, obtaining various fatigue performance indicators of steel strands or parallel steel wires through tension-bending fatigue testing. However, it cannot perform cable bending friction corrosion fatigue testing under torsion, fretting fatigue wear, and electrochemical corrosion coupling conditions. Chinese invention patent CN120293678A, entitled "Test Device and Method for Accelerated Corrosion Testing of Bridge Cables under Tension-Bending Coupling," discloses a test device and method for accelerated corrosion testing of bridge cables under tension-bending coupling conditions. It can simulate the corrosion conditions of bridge cables under tension-bending coupling, thereby evaluating the corrosion resistance of cable specimens. However, it fails to realize the complex conditions of cable torsion and fretting fatigue wear, and cannot collect damage location information in real time. Chinese invention patent with publication number "CN117517103A" and titled "A Corrosion-Fatigue Coupled Durability Test System and Method for Suspension Bridge Cables" discloses a corrosion-fatigue coupled durability test system and method for suspension bridge cables. It can simulate the simultaneous corrosion and fatigue failure of cables during actual service, collect comprehensive damage information of cables, and perform displacement and strain analysis on damage images. However, it cannot realize the complex working conditions of cable torsion and fretting fatigue wear. Summary of the Invention

[0005] To address the problem that existing cable testing devices cannot perform tests on complex conditions such as cable torsion and fretting fatigue wear, this invention provides a tensile, bending, torsional, frictional, and corrosion fatigue testing device and method for straddle-type suspension cables of suspension bridges. By integrating functions such as fatigue loading, bending simulation, torsion application, environmental simulation, and data acquisition, it accurately reproduces the multi-factor coupled conditions in actual service of straddle-type suspension cables, enabling the exploration of damage evolution laws, fatigue life, and failure mechanisms of straddle-type suspension cables of suspension bridges.

[0006] This invention is achieved through the following technical solution: It includes a rack module, a drive module, an environment simulation module, and a data acquisition and processing module. The rack module includes multiple vertically arranged support columns fixed to the rack base plate, a horizontally arranged central beam and support platform, two vertical beams arranged between the support platform and the central beam, a top beam arranged on top of the support columns, and a rack top plate covering the top beam. The drive module includes a servo controller, a servo electric cylinder, and a heavy-duty turntable mounted on the rack base plate. The servo electric cylinder is vertically arranged with its output end facing away from the rack base plate. The output end of the servo electric cylinder is connected to a first tension sensor and a first lifting ring. A second tension sensor and a second lifting ring are connected to the heavy-duty turntable, and the two ends of the lifting cable are connected to the first and second lifting rings respectively. The drive module also includes horizontally arranged support columns... The support platform includes a ball screw mechanism comprising a guide rail and a moving table. The ball screw mechanism is driven by a servo motor. A sling groove is fixedly connected to the moving table, and the sling is fitted onto the sling groove in the middle. The data acquisition and processing module includes a first tension sensor, a second tension sensor, a laser displacement sensor fixed via an upper crossbeam, a temperature and humidity sensor fixed to the top plate of the frame, a first high-speed camera fixed to the top plate of the frame via a camera bracket, and a second and third high-speed cameras fixed to two vertical beams respectively. The installation direction of the first high-speed camera is perpendicular to the plane where the sling is located. The heavy-duty turntable, servo motor, first tension sensor, second tension sensor, laser displacement sensor, temperature and humidity sensor, first high-speed camera, second high-speed camera, and third high-speed camera are all connected to a host computer via data cables.

[0007] As a further preferred embodiment, the environmental simulation module includes a corrosion liquid storage tank, a full-spectrum solar spotlight, and an ultraviolet spotlight; the corrosion liquid storage tank is connected to a water inlet pipe, the other end of which passes through a liquid passage hole on the support platform and is connected to a corrosion liquid nozzle; the full-spectrum solar spotlight and the ultraviolet spotlight are both fixed to the top plate of the frame, symmetrically distributed on both sides of the sling groove, and both point to the top of the middle of the sling groove; the full-spectrum solar spotlight, the ultraviolet spotlight, and the sling are on the same plane.

[0008] As a further preferred embodiment, a sling clamp is fixed to the sling located between the support platform and the central crossbeam, and a first conical block and a second conical block are respectively fixed to the sling on the side of the sling away from the support platform.

[0009] As a further preferred embodiment, a side plate is provided within the range from the middle crossbeam to the top crossbeam to enclose the middle and upper supporting columns into a closed space. The horizontally arranged side plate located at the middle crossbeam is provided with through holes and water outlet holes.

[0010] As a further preferred embodiment, the corrosive liquid storage tank is also connected to a water outlet pipe, the other end of which is connected to a water outlet hole on a horizontally arranged side plate at the central crossbeam.

[0011] As a further preferred embodiment, the sling groove is provided with uniformly distributed scale grooves on both planes along the guide rail direction of the ball screw mechanism, with 3 scale grooves arranged on each side, and the 3 scale grooves are arranged in a circular array, spaced 30° apart.

[0012] As a further preferred embodiment, an extension platform is provided on one side of the support platform, and a groove for placing a servo motor is provided in the middle of the extension platform.

[0013] As a further preferred embodiment, the through holes on the horizontally arranged side plates at the central crossbeam are respectively provided with a first O-ring and a second O-ring, and the side plates covering the supporting columns are made of transparent acrylic sheets.

[0014] As a further preferred embodiment, both the first and second tension sensors are S-shaped tension sensors, with a support column side support provided on the side of each support column, and two support brackets provided between the extension platform and the support column.

[0015] The present invention also provides a test method applicable to the suspension bridge straddle cable tension-bending-torsion friction corrosion fatigue test device described in the present invention, comprising the following steps:

[0016] S1. Install a side panel onto the upper part of the middle crossbeam;

[0017] S2. Zero the first tension sensor and the second tension sensor;

[0018] S3. Install the sling into the sling groove, and install the sling clamp, the first conical block, and the second conical block to the middle position of the sling; lead the two ends of the sling out from the through holes of the side plate, and connect the two ends of the sling to the first lifting ring and the second lifting ring, respectively;

[0019] S4. The servo electric cylinder is controlled by the servo controller to tighten the sling to the predetermined value;

[0020] S5. Readjust the positions of the sling clamp, the first conical block, and the second conical block;

[0021] S6. Set the specific parameters of the servo electric cylinder through the servo controller; set the torsion angle, torsion speed and cycle number of the heavy-duty turntable through the host computer; set the lateral displacement, lateral speed and cycle number of the ball screw mechanism.

[0022] S7. Connect the remaining side panels to the frame;

[0023] S8. Open the data acquisition interface and high-speed camera monitoring interface on the host computer and start recording relevant data;

[0024] S9. The servo electric cylinder, ball screw mechanism and heavy-duty turntable are operated, and the corrosion liquid nozzles begin to spray the corrosion liquid evenly.

[0025] S10. The host computer acquires the working status of the servo electric cylinder, ball screw mechanism and heavy-duty turntable in real time. When the number of cycles of operation of the three reaches the numerical threshold preset in step S, the experiment is stopped.

[0026] S11. The relevant data collected during the experiment are processed and analyzed by the host computer to obtain the friction coefficient change curve and dynamic slip amplitude of the sling, and the friction behavior of the two ends of the sling above the sling clamp.

[0027] S12. Repeat steps S1-S11. By adjusting key variables such as sling wrap angle, fatigue load, tensile speed, torsion angle, torsion speed, lateral displacement, and lateral speed, conduct sling tension, bending, torsion, friction, corrosion fatigue tests under different working conditions to explore the tribological behavior of the sling.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. This invention integrates fatigue loading, bending simulation, torsion application, and corrosion environment simulation through multi-module collaborative operation, accurately reproducing the multi-factor coupling effect of "tension, bending, torsion, friction, corrosion, and fatigue," overcoming the shortcomings of existing devices that cannot cover complex working conditions. Single or combined working condition experiments can be conducted through different combinations of drive modules, and key variables such as the wrap angle, load, and speed can be adjusted to adapt to different testing requirements. It accurately simulates environmental conditions such as corrosive media, ultraviolet aging, and temperature control. Through multiple sensors and a high-speed camera, it simultaneously acquires data such as tensile force, friction coefficient, displacement, temperature, and humidity, as well as dynamic contact images, enabling in-depth research into damage evolution and failure mechanisms. This device is easy to operate, fully functional, and has excellent application results, possessing broad application value in its technical field. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the fatigue testing device of the present invention.

[0031] Figure 2 This is a schematic diagram of the internal structure of the fatigue testing device of the present invention.

[0032] Figure 3 This is a schematic diagram of the frame structure of the fatigue testing device of the present invention.

[0033] Figure 4 This is a schematic diagram of the transverse loading structure of the fatigue testing device of the present invention.

[0034] Figure 5 This is a schematic diagram of the tension change curves at both ends of the sling during the experiment of this invention.

[0035] Figure 6 This is a schematic diagram illustrating displacement tracking during the relative sliding process between the sling and the sling groove in the experiment of this invention.

[0036] Figure 7 This is a schematic diagram showing the test parameters of each component of the fatigue testing device of the present invention.

[0037] The image shows:

[0038] 1. Frame base plate; 2. Servo controller; 3. Servo electric cylinder; 4. First tension sensor; 5. First lifting ring; 6. Lifting sling; 7. Transparent acrylic sheet; 8. Ball screw mechanism; 9. Water inlet pipe; 10. Water outlet pipe; 11. Second lifting ring; 12. Second tension sensor; 13. Heavy-duty turntable; 14. Corrosion solution storage tank; 15. First conical casting block; 16. Second conical casting block; 17. Lifting sling clamp; 18. Moving stage; 19. Guide rail; 20. Servo motor; 21. Laser displacement sensor; 22. Full-spectrum solar spotlight; 23. Ultraviolet spotlight; 24. Temperature and humidity sensor; 25. First high-speed camera; 26. Camera bracket; 27. Lifting sling groove; 28. Corrosion solution nozzle; 29. ​​Second... 30. High-speed camera; 31. First O-ring seal; 32. Second O-ring seal; 33. First support column; 34. Side support of the first support column; 35. Side support of the second support column; 36. Second support column; 37. Middle crossbeam; 38. First vertical beam; 39. Second vertical beam; 40. Support platform; 41. Fluid passage hole; 42. Top crossbeam; 43. Frame top plate; 44. Side plate of support platform; 45. Upper crossbeam; 46. Extension platform; 47. Groove; 48. First support inclined frame; 49. Second support inclined frame; 50. Third support column; 51. Fourth support column; 52. Side support of the third support column; 53. Side support of the fourth support column; 54. Scale groove. Detailed Implementation

[0039] The advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments, which are given by way of example only with reference to the accompanying drawings.

[0040] like Figures 1 to 4 As shown, the present invention provides a fatigue testing device for tension, bending, torsion, friction, corrosion and fatigue of suspension bridge straddle cables. The fatigue testing device includes a frame module, a drive module, an environmental simulation module and a data acquisition and processing module.

[0041] The rack module serves as the mounting base for other functional modules, supporting the entire weight of the drive module, environmental simulation module, and data acquisition and processing module, ensuring the overall structural stability after assembly. Side supports are added to one side of each support column of the rack module, and a diagonal support frame is installed below the extension platform. These support components ensure the overall stability of the rack module meets usage requirements.

[0042] like Figure 3 As shown, the rack module includes multiple vertically arranged support columns fixed to the rack base plate 1, a central crossbeam 37, and a support platform 40. Both the central crossbeam 37 and the support platform 40 are horizontally arranged, dividing the support columns into three parts from bottom to top. To enhance the stability of the rack module, side supports can be provided on the side of each support column. Preferably, there are four support columns: a first support column 33, a second support column 36, a third support column 50, and a fourth support column 51. Correspondingly, there are also four side supports: a first support column side support 34, a second support column side support 35, a third support column side support 52, and a fourth support column side support 53. Two vertical beams, a first vertical beam 38 and a second vertical beam 39, are provided between the support platform 40 and the central crossbeam 37, respectively used to mount the second high-speed camera 29 and the third high-speed camera 30. To increase the experimental range of the entire fatigue testing apparatus, an extension platform 46 can be set on one side of the support platform 40. A groove 47 for placing the servo motor 20 is provided in the middle of the extension platform 46. To enhance the stability of the extension platform 46, two supporting inclined frames, namely a first supporting inclined frame 48 and a second supporting inclined frame 49, can be set between the extension platform 46 and the support column. The support platform 40 also has several perforations to prevent interference with the movement of the suspension cable during subsequent experiments. Support platform side plates are provided at corresponding positions of the perforations on the support platform 40, and liquid passage holes 41 are provided on the support platform side plates. These liquid passage holes 41 are used to connect to the water inlet pipe 10 to facilitate the flow of corrosive liquid to the suspension cable. To facilitate control of environmental factors, the frame module also includes a top crossbeam 42, which is horizontally positioned on top of the support columns. A frame top plate 43 covers the top crossbeam 42. Side plates are provided between the middle crossbeam 37 and the top crossbeam 42, enclosing the upper and middle support columns into a closed space. The horizontally positioned side plates at the middle crossbeam 37 have through holes for the hoisting slings 6 to pass through and outlet holes for the corrosive liquid to flow out. For ease of reading and observation of the test process, the side plates enclosing the support columns are made of transparent acrylic sheets 7. An upper crossbeam 45 is also provided on the support columns between the support platform 40 and the top crossbeam 42 for fixing the laser displacement sensor 21.

[0043] like Figure 1 , Figure 2 and Figure 4As shown, the drive module includes a servo controller 2, a servo electric cylinder 3, and a heavy-duty turntable 13 mounted on the frame base plate 1. The servo electric cylinder 3 is vertically positioned with its output end facing away from the frame base plate 1. The output end of the servo electric cylinder 3 is connected to a first tension sensor 4 and a first lifting ring 5. A second tension sensor 12 and a second lifting ring 11 are connected to the heavy-duty turntable 13. The two ends of the sling 6 are connected to the first lifting ring 5 and the second lifting ring 11, respectively. The drive module also includes a ball screw mechanism 8 horizontally mounted on the support platform 40. The ball screw mechanism 8 includes a guide rail 19 and a moving platform 18, i.e., a slider that cooperates with the guide rail 19. The ball screw mechanism 8 is driven by a servo motor 20, which is located in a groove 47 of the extension platform 46. A sling rope groove 27 is fixedly connected to the moving platform 18, and the middle part of the sling 6 is sleeved on the sling rope groove 27. A sling clamp 17 is fixed on the sling 6 located between the support platform 40 and the central crossbeam 37. A first conical block 15 and a second conical block 16 are respectively fixed on the sling 6 on the side of the sling clamp 17 away from the support platform 40.

[0044] The servo controller 2 is connected to the servo electric cylinder 3 via a data cable, thereby controlling the relevant loading parameters of the servo electric cylinder 3. The sling 6 has a double-layer structure design, with a load-bearing steel wire rope inside and a non-metallic coating on the outside. The sling groove 27 has evenly distributed graduated grooves 54 on two planes along the guide rail 19 of the ball screw mechanism 8, with three graduated grooves 54 arranged on each side. The three graduated grooves are arranged in a circular array, spaced 30° apart. Figure 6 As shown in the left figure, the lifting sling clamp 17, the first conical casting block 15, and the second conical casting block 16 can adjust the wrap angle of the lifting sling 6 by moving them up and down.

[0045] like Figure 1 and Figure 2 As shown, the environmental simulation module includes a corrosion liquid storage tank 14, a full-spectrum solar spotlight 22, and an ultraviolet spotlight 23. The corrosion liquid storage tank 14 is connected to an inlet pipe 9 and an outlet pipe 10. The other end of the inlet pipe 9 passes through a liquid passage hole 41 on the support platform 40 and connects to the corrosion liquid nozzle 28. The other end of the outlet pipe 10 connects to an outlet hole on a horizontally positioned side plate at the central crossbeam 37. To prevent corrosion liquid leakage, a first O-ring 31 and a second O-ring 32 are respectively installed at the through holes for the hoisting cable 6 to pass through on the horizontally positioned side plate at the central crossbeam 37. The full-spectrum solar spotlight 22 and the ultraviolet spotlight 23 are both fixed to the top plate 43 of the frame, symmetrically distributed on both sides of the hoisting cable groove 27, and both point towards the top center of the hoisting cable groove 27. The full-spectrum solar spotlight 22, the ultraviolet spotlight 23, and the hoisting cable 6 are on the same plane.

[0046] During the experiment, the corrosive liquid in the corrosion liquid storage tank 14 is transported to the liquid passage hole 41 through the water inlet pipe 9. After being atomized by the corrosion liquid nozzle 28, it is sprayed out in a uniform spray form. Utilizing the relatively enclosed space formed by the transparent acrylic plate 7, the supporting column, and the crossbeam, the corrosion conditions of the suspension cable 6 in a salt spray environment are accurately simulated. The corrosive liquid formed after spraying and liquefaction flows along the surface of the transparent acrylic plate 7 above the central crossbeam 37, flows into the water outlet pipe 10 through the outlet, and finally flows back to the corrosion liquid storage tank 14 for recycling. At the same time, the temperature and humidity sensor 24 installed in the enclosed space collects the environmental temperature and humidity parameters in real time and transmits the data synchronously to the host computer for real-time monitoring of the environmental status. The ultraviolet spotlight 23 can be flexibly turned on according to the preset experimental requirements to accurately simulate the aging process of the non-metallic coating on the surface of the sling 6 under ultraviolet radiation in the natural environment; the full-spectrum solar spotlight 22 has a dual function. On the one hand, it provides sufficient and uniform light source for the high-speed camera to capture the dynamic contact process between the sling 6 and the sling groove 27. On the other hand, by adjusting the irradiation intensity, the temperature of the contact area between the sling 6 and the sling groove 27 can be kept stable within the experimental setting range, ensuring the consistency of experimental environmental parameters.

[0047] The full-spectrum solar spotlight 22 illuminates the top of the sling 6 in a directional manner, providing a light source for high-speed camera shooting while ensuring that the temperature of the sling 6 remains within a certain temperature range. The ultraviolet spotlight 23 illuminates the top of the sling 6 in a directional manner, thereby simulating the aging process of the non-metallic coating on the outside of the sling 6 under ultraviolet light.

[0048] like Figure 1 and Figure 2As shown, the data acquisition and processing module includes a first tension sensor 4, a second tension sensor 12, a laser displacement sensor 21, a temperature and humidity sensor 24, a first high-speed camera 25, a second high-speed camera 29, and a third high-speed camera 30. Both the first tension sensor 4 and the second tension sensor 12 are S-shaped tension sensors. The first high-speed camera 25 is fixed to the top plate 43 of the frame via a camera bracket 26, and its installation direction is perpendicular to the plane where the sling 6 is located. The temperature and humidity sensor 24 is fixed to the top plate 43 of the frame. The second high-speed camera 29 and the third high-speed camera 30 are respectively fixed at the middle positions of the first vertical beam 38 and the second vertical beam 39, and are located on the same horizontal plane as the top of the sling clamp 17. The first tension sensor 4, the second tension sensor 12, the laser displacement sensor 21, the temperature and humidity sensor 24, the first high-speed camera 25, the second high-speed camera 29, and the third high-speed camera 30 are all connected to a host computer via data cables for data processing. The aforementioned sensors can acquire real-time images of the contact points between the sling 6 and the sling groove 27, and between the sling 6 and the sling clamp 17 during the experiment; obtain the real-time tension at both ends of the sling 6; and upload the data to the host computer. Through post-processing, the real-time friction coefficient change curve at the sling 6 and the sling groove 27 can be obtained.

[0049] The formula for calculating the friction coefficient of the sling is:

[0050] ;

[0051] In the formula, The angle of wrapping between the sling 6 and the sling groove 27 is represented; F1 and F2 are the tensions at both ends of the sling 6. Specifically, F1 is the tension of the sling 6 at the end where the fatigue load is applied by the servo electric cylinder 3, and F2 is the tension of the sling 6 at the end of the heavy-duty turntable 13. Both F1 and F2 are acquired by tension sensors. In the example experiment, the tension changes at both ends of the sling 6 as follows: Figure 5 As shown, this invention selects the average tension of cable 6 when the fatigue load exceeds 80% of the maximum value within a single cycle as the average tension at both ends of cable 6 for the corresponding cycle. The average friction coefficient for this cycle is calculated using the formula for calculating the friction coefficient of the cable. Combining the variation law of the friction coefficient, the average friction coefficient is selected according to different intervals for different fatigue cycles, and finally a friction coefficient curve is plotted.

[0052] The dynamic contact test between the sling 6 and the sling groove 27 during the experiment was achieved through the following method:

[0053] The first high-speed camera 25 is connected to the host computer via a data cable to capture real-time images of the sling 6 and the sling groove 27 during the experiment, enabling dynamic contact testing between the sling 6 and the sling groove 27. Three graduated grooves 54 are evenly distributed on both sides of the sling groove 27, with adjacent grooves 54 spaced 30° apart. Each groove 54 corresponds to an observation area. Observation area 1 is located at the center of the sling groove 27, observation area 2 is near the servo electric cylinder 3, and observation area 3 is near the heavy-duty turntable 13. A red marker is placed at the center of each of observation areas 1, 2, and 3 as a reference point. A black tracking point is marked on the sling 6, and the displacement change of the black tracking point relative to the red marker is observed. Using a polar coordinate system, the red marker on the cable groove 27 is the pole. Taking observation area 1 as an example, the line connecting the black tracking point on cable 6 and the pole is the polar axis. During the experiment, the distance between the black tracking point and the pole is the polar radius ρ, and the angle between the polar radius and the polar axis is the polar angle θ. The real-time position coordinates of the black tracking point are (ρ, θ). The polar angle is in radians. Therefore, the displacement change of cable 6 is ρ∙θ. Figure 6 As shown. The above process is implemented in the host computer through subsequent processing.

[0054] like Figure 7 The diagram shown is a schematic representation of the test parameters for each component of the fatigue testing device of the present invention.

[0055] The present invention also provides a test method applicable to the suspension bridge straddle cable tension, bending, torsion, friction, corrosion fatigue test device described in the present invention, for conducting cable tension, bending, torsion, friction, corrosion fatigue tests, the specific steps of which are as follows:

[0056] S1. Before the experiment, a transparent acrylic plate 7 is installed on the upper part of the middle crossbeam 27, and the first O-ring 31 and the second O-ring 32 are installed into the reserved holes of the transparent acrylic plate 7.

[0057] S2. Zero the first tension sensor 4 and the second tension sensor 12.

[0058] S3. Cut a certain length of sling 6 and install the sling 6 into the sling groove 27. Install the sling clamp 17, the first conical casting 15, and the second conical casting 16 into the middle position of the sling 6. Lead both ends of the sling 6 out from the first O-ring 31 and the second O-ring 32 respectively, and connect both ends of the sling 6 to the first lifting ring 5 and the second lifting ring 11 respectively.

[0059] S4. The servo controller 2 controls the servo electric cylinder 3 to tighten the sling 6. By observing the value of the tension sensor in the host computer, the tension of the sling 6 is made to reach the predetermined value.

[0060] S5. Readjust the positions of the sling clamp 17, the first conical casting block 15, and the second conical casting block 16.

[0061] S6. Set specific parameters through the servo controller 2 to regulate the fatigue load, tension speed and cycle number of the servo electric cylinder 3; set the torsion angle, torsion speed and cycle number of the heavy-duty turntable 13 through the host computer; set the lateral displacement, lateral speed and cycle number of the ball screw mechanism 8.

[0062] S7. Connect the remaining transparent acrylic sheet 7 to the frame with bolts to form a relatively sealed space.

[0063] S8. Open the data acquisition interface and high-speed camera monitoring interface on the host computer and start recording relevant data.

[0064] S9. Start the experiment. Run the servo electric cylinder 3, ball screw mechanism 8 and heavy-duty turntable 13 according to the pre-set parameters. The corrosion liquid nozzle 28 in the sealed space formed in step S7 starts to spray the corrosion liquid evenly.

[0065] S10. During the experiment, the host computer acquires the working status (fatigue load, tensile speed, torsion angle, torsion speed, lateral displacement, and lateral speed) of the servo electric cylinder 3, ball screw mechanism 8, and heavy-duty turntable 13 in real time. When the number of cycles of operation of the three components reaches the numerical threshold preset in step S6, the experiment is stopped.

[0066] S11. The relevant data collected during the experiment are processed and analyzed by the host computer to obtain the friction coefficient change curve and dynamic slip amplitude of the sling 6, and the friction behavior of the two ends of the sling 6 above the sling clamp 17.

[0067] S12. Repeat steps S1-S11. By adjusting key variables such as sling wrap angle, fatigue load, tensile speed, torsion angle, torsion speed, lateral displacement, and lateral speed, conduct sling tension, bending, torsion, friction, corrosion fatigue tests under different working conditions to explore the tribological behavior of the sling.

[0068] In this invention, during the experimental operation phase of step S9, the experimental conditions can be adjusted by regulating the start and stop states of the relevant mechanisms: the lateral movement of the ball screw mechanism 8 and the torsional drive of the heavy-duty turntable 13 are turned off, and only the servo electric cylinder 3 is kept running stably according to preset parameters. With the help of the fatigue load and tensile action provided by the servo electric cylinder 3, combined with the corrosive liquid spraying environment in the sealed space and the contact structure between the sling 6 and the sling groove 27, the bending friction corrosion fatigue test of the sling can be carried out accurately, providing a reliable experimental scheme for studying the tribological characteristics and corrosion fatigue behavior of the sling 6 under bending conditions.

[0069] In addition to the above embodiments, the present invention may have other implementation methods. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A fatigue testing device for tension, bending, torsion, friction, corrosion, and stress of suspension bridge straddle cables, comprising a frame module, a drive module, an environmental simulation module, and a data acquisition and processing module, characterized in that: The frame module includes multiple vertically arranged support columns fixed to the frame base plate (1), a horizontally arranged central crossbeam (37) and support platform (40), two vertical beams arranged between the support platform (40) and the central crossbeam (37), a top crossbeam (42) arranged on top of the support columns, and a frame top plate (43) covering the top crossbeam (42); the drive module includes a servo controller (2), a servo electric cylinder (3), and a heavy-duty turntable (13) arranged on the frame base plate (1), wherein the servo electric cylinder (3) The servo electric cylinder (3) is vertically positioned with its output end facing away from the base plate (1). The output end of the servo electric cylinder (3) is connected to a first tension sensor (4) and a first lifting ring (5). A second tension sensor (12) and a second lifting ring (11) are connected to the heavy-duty turntable (13). The two ends of the sling (6) are connected to the first lifting ring (5) and the second lifting ring (11), respectively. The drive module also includes a ball screw mechanism (8) horizontally positioned on the support platform (40). The ball screw mechanism (8) includes a guide rail (19) and a moving table (18). The ball screw mechanism (8) is driven by a servo motor (20). A sling groove (27) is fixedly connected to the moving platform (18). The sling (6) is sleeved in the middle of the sling groove (27). The data acquisition and processing module includes a first tension sensor (4), a second tension sensor (12), a laser displacement sensor (21) fixed by an upper crossbeam (45), a temperature and humidity sensor (24) fixed to the top plate (43) of the frame, and a first high-pressure sensor fixedly connected to the top plate (43) of the frame by a camera bracket (26). The high-speed camera (25), the second high-speed camera (29) and the third high-speed camera (30) are fixedly connected to the two vertical beams respectively. The installation direction of the first high-speed camera (25) is perpendicular to the plane where the sling (6) is located. The heavy-duty turntable (13), servo motor (20), first tension sensor (4), second tension sensor (12), laser displacement sensor (21), temperature and humidity sensor (24), first high-speed camera (25), second high-speed camera (29) and third high-speed camera (30) are all connected to the host computer through data cables.

2. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 1, characterized in that: The environmental simulation module includes a corrosion liquid storage tank (14), a full-spectrum solar spotlight (22), and an ultraviolet spotlight (23). A water inlet pipe (9) is connected to the corrosion liquid storage tank (14). The other end of the water inlet pipe (9) passes through the liquid passage hole (41) on the support platform (40) and is connected to the corrosion liquid nozzle (28). The full-spectrum solar spotlight (22) and the ultraviolet spotlight (23) are both fixed to the top plate (43) of the frame and are symmetrically distributed on both sides of the sling rope groove (27), both pointing to the top of the middle of the sling rope groove (27). The full-spectrum solar spotlight (22), the ultraviolet spotlight (23), and the sling (6) are on the same plane.

3. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 2, characterized in that: A sling clamp (17) is fixed on the sling (6) located between the support platform (40) and the middle crossbeam (37). A first conical block (15) and a second conical block (16) are fixed on the sling (6) on the side of the sling (6) away from the support platform (40).

4. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 3, characterized in that: Side plates are provided within the range from the middle crossbeam (37) to the top crossbeam (42), which enclose the middle and upper support columns into a closed space. The side plates located at the middle crossbeam (37) are provided with through holes and water outlet holes.

5. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 4, characterized in that: The corrosive liquid storage tank (14) is also connected to the water outlet pipe (10), and the other end of the water outlet pipe (10) is connected to the water outlet hole on the horizontally arranged side plate at the middle crossbeam (37).

6. The suspension bridge straddle cable tension-bending-torsion-friction corrosion fatigue test device according to claim (5), characterized in that: The sling groove (27) is provided with uniformly distributed scale grooves (54) on two planes along the guide rail (19) of the ball screw mechanism (8). Three scale grooves (54) are arranged on each side, and the three scale grooves are arranged in a circular array, spaced 30° apart.

7. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 6, characterized in that: An extension platform (46) is provided on one side of the support platform (40), and a groove (47) for placing a servo motor (20) is provided in the middle of the extension platform (46).

8. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 6, characterized in that: The horizontal side plate at the central crossbeam (37) is provided with a first O-ring (31) and a second O-ring (32) respectively at the through holes, and the side plate covering the supporting column is a transparent acrylic plate.

9. The suspension bridge straddle-type cable tension, bending, torsion, friction, corrosion fatigue testing device according to claim 6, characterized in that: The first tension sensor (4) and the second tension sensor (12) are both S-shaped tension sensors. Supporting columns are provided on the side of each supporting column, and two supporting inclined frames are provided between the extension platform (46) and the supporting column.

10. A test method applicable to the suspension bridge straddle cable tension-bending-torsion-friction corrosion fatigue test apparatus according to any one of claims 6 to 9, characterized in that: Includes the following steps: S1. Install a side plate onto the upper part of the middle crossbeam (27); S2. Zero the first tension sensor (4) and the second tension sensor (12); S3. Install the sling (6) into the sling groove (27), and install the sling clamp (17), the first conical block (15), and the second conical block (16) into the middle position of the sling (6); lead the two ends of the sling (6) out from the through holes of the side plate, and connect the two ends of the sling (6) to the first lifting ring (5) and the second lifting ring (11) respectively; S4. The servo electric cylinder (3) is controlled by the servo controller (2) to tighten the sling (6) to the predetermined value. S5. Readjust the positions of the sling clamp (17), the first conical block (15), and the second conical block (16); S6. Set the specific parameters of the servo electric cylinder (3) through the servo controller (2); set the torsion angle, torsion speed and cycle number of the heavy-duty turntable (13) through the host computer; set the lateral displacement, lateral speed and cycle number of the ball screw mechanism (8); S7. Connect the remaining side panels to the frame; S8. Open the data acquisition interface and high-speed camera monitoring interface on the host computer and start recording relevant data; S9. Run the servo electric cylinder (3), ball screw mechanism (8) and heavy-duty turntable (13), and the corrosion liquid nozzle (28) starts to spray corrosion liquid evenly. S10. The host computer acquires the working status of the servo electric cylinder (3), ball screw mechanism (8) and heavy-duty turntable (13) in real time. When the number of cycles of operation of the three reaches the numerical threshold set in step S (6), the experiment is stopped. S11. The relevant data collected during the experiment are processed and analyzed by the host computer to obtain the friction coefficient change curve and dynamic slip amplitude of the sling (6), and the friction behavior of the two ends of the sling (6) above the sling clamp (17). S12. Repeat steps S1-S11. By adjusting key variables such as sling wrap angle, fatigue load, tensile speed, torsion angle, torsion speed, lateral displacement, and lateral speed, conduct sling tension, bending, torsion, friction, corrosion fatigue tests under different working conditions to explore the tribological behavior of the sling.

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