A device for simulating fretting fatigue wear of wire ropes and an evaluation method

Abstract

The present invention discloses a device and evaluation method for simulating fretting fatigue wear of a steel wire rope. The device comprises a test bench, a control system, an anchoring device disposed on the test bench for anchoring the steel wire rope, a loading system symmetrically disposed above and below the test bench, and a chuck and a fixture respectively disposed on the loading system for clamping the anchoring device. The anchoring device comprises a body, through which a first cavity and a second cavity are connected. The diameter of the first cavity matches that of the steel wire rope and is used to pass through a portion of the steel wire rope that remains in its original state. The diameter of the second cavity is twice that of the steel wire rope and is used to pass through a portion of the steel wire rope that is in a dispersed strand state. The present invention can simulate the load conditions of a steel wire rope under actual working conditions and evaluate the impact of the fretting fatigue wear of the steel wire rope on the mechanical properties and life of the steel wire rope based on the damage to the mechanical properties of the steel wire rope after the fretting fatigue wear test and the damage to the mechanical properties of the strands of the steel wire rope after stripping.

Description

Technical Field

[0001] The present invention relates to a fatigue wear simulation device and an evaluation method, and in particular to a wire rope fretting fatigue wear simulation device and an evaluation method. Background Art

[0002] Due to their unique production process and structure, steel wire ropes possess excellent load-bearing capacity and bending properties. Therefore, they are widely used as traction and load-bearing components in mines, cableways, suspension bridges, cranes, and other applications. Wire ropes used in lifting equipment such as mines and cranes are subject to impact loads. Due to their multi-filament, multi-strand, spatially spiral structure, they experience a coupling of tension, torsion, and bending when subjected to axial tension. Combined with harsh operating environments, this results in diverse and uncertain micro-motion damage to the strands within the wire rope. Wire ropes used in cableways and suspension bridges are subject to breeze vibration loads. Breeze vibration refers to high-frequency (3-50 Hz), low-amplitude (0.3-0.7 times the wire diameter) vibrations of wire ropes at low wind speeds (0.5-10 m / s). When wind blows laterally against the stay cables, a stable Karman vortex street forms behind them, causing vertical vibrations in the wire rope. When the vibration frequency approaches the natural frequency of the wire rope, resonance occurs. Resonance frequently occurs during the service life of wire ropes. Its small amplitude and high frequency make it difficult to observe with the naked eye and, therefore, difficult to detect during inspection. This causes the wire rope to vibrate for long periods of time, and the wear caused by micro-motion accumulates, gradually developing into micro-motion fatigue. Micro-motion fatigue is the most common form of damage and failure for wire ropes under actual operating conditions. It will cause the effective cross-sectional area of the wire rope to decrease, seriously affecting the service strength of the wire rope. When some wires in the wire rope reach their fatigue limit, they will break, or even break due to fatigue. Current research results have not yet fully grasped the micro-motion damage characteristics and failure mechanisms of wire ropes, making it difficult to accurately determine the remaining safe service life of serving wire ropes. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a device for simulating the fretting fatigue wear of a steel wire rope that can simulate the actual working conditions during the service of the steel wire rope;

[0004] The second object of the present invention is to provide a method for evaluating the damage caused by fretting fatigue wear to the mechanical properties of a steel wire rope using the above-mentioned steel wire rope fretting fatigue wear simulation device.

[0005] Technical solution: The wire rope micro-fatigue wear simulation device described in the present invention includes a test bench, a control system, and an anchoring device arranged on the test bench for anchoring the wire rope. Loading systems are symmetrically arranged above and below the test bench, and the two loading systems are respectively provided with clamping devices for clamping the anchoring device; the anchoring device includes a main body, and a first cavity and a second cavity are connected to each other through the main body. The first cavity is used to allow a section of the wire rope that remains in its original state to pass through, and the second cavity is used to allow a section of the wire rope that is in a dispersed state to pass through; the diameter of the first cavity is the same as the diameter of the wire rope, and the diameter of the second cavity is larger than the diameter of the wire rope.

[0006] Wherein, the length of the first cavity is smaller than the length of the second cavity.

[0007] The length of the first cavity is 1:3-1:4 of the length of the second cavity.

[0008] Wherein, the diameter of the second cavity is twice the diameter of the steel wire rope.

[0009] Wherein, the body is a bolt, the first cavity extends through the bolt head to the bolt rod, and the second cavity is arranged in the bolt rod.

[0010] The clamping device includes a clamp fixed on the loading system and a fixture fixed on the clamp for clamping the anchoring device; the fixture is controlled by the loading system to achieve clamping.

[0011] The control system includes a microcomputer for setting parameters of fretting fatigue wear experiments and a data acquisition system.

[0012] The method for evaluating the wear of a steel wire rope using the above-mentioned steel wire rope fretting fatigue wear simulation device comprises the following steps:

[0013] (A) A length of the original steel wire rope and a steel wire rope with the strands at both ends dispersed are fixed at the corresponding positions at the upper and lower ends of the steel wire rope respectively by anchoring devices, and then the two anchoring devices are clamped to the clamping devices respectively;

[0014] (B) Adjust the distance between the upper and lower loading systems so that the wire rope is subjected to axial tension on the test bench, and then lock the upper loading system. Set the experimental parameters for fretting fatigue wear through the control system, and reset the position and initial load of the clamping device.

[0015] (D) The loading system is controlled by the control system to perform axial tensile loading / unloading on the wire rope, and a fretting fatigue wear test is performed according to the set experimental parameters; the control system collects different sensor output signals, records them in the control system, and obtains the changes in the axial displacement and axial tension of the wire rope with the number of loading times under different fretting fatigue wear experimental parameters;

[0016] (E) Repeat steps (A to D) to conduct an orthogonal test of the load level and the number of fretting fatigue wear on the wire rope, collect the output signals of different sensors, and record them in the control system;

[0017] (F) performing mechanical property testing on the steel wire rope that completed the orthogonal test in step (E); performing calculations, comparisons, and analyses based on the collected data to evaluate the loss of mechanical properties and the life of the steel wire rope after fretting fatigue wear;

[0018] (G) peeling the steel wire rope after the orthogonal test in step (E) to observe the breakage of the strands inside the steel wire rope after fretting fatigue wear, counting the number of broken wires and broken strands, and measuring the mechanical properties of the intact strands after the steel wire rope is peeled;

[0019] (H) Statistically analyzing the internal strand-wire mechanical properties of the steel wire rope measured in step (G) to evaluate the fretting fatigue wear conditions of the steel wire rope under different working conditions and its effect on the mechanical properties of the steel wire rope.

[0020] Wherein, step (C) includes load level, micro-motion load mode, micro-motion frequency, micro-motion frequency, and data acquisition frequency;

[0021] Wherein, in step (H), the fretting fatigue wear condition of the wire rope under different working conditions and its influence on the mechanical properties of the wire rope are evaluated based on the number of broken wires, the strand-wire mechanical property damage and the mechanical property damage of the wire rope.

[0022] In step (B), the position and initial load of the chuck are preferably reset;

[0023] In step (D), the steel wire rope is axially stretched and loaded / unloaded by a loading system controlled by a microcomputer; and different sensor output signals are collected by a data acquisition system and recorded on the data acquisition system.

[0024] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0025] (1) The fretting fatigue wear simulation test device can be used to simulate the load condition of the wire rope under actual working conditions. The influence of the fretting fatigue wear of the wire rope on the mechanical properties and life of the wire rope can be evaluated based on the damage condition of the mechanical properties of the wire rope after the fretting fatigue wear test and the damage condition of the mechanical properties of the strands of the wire rope after stripping.

[0026] (2) The present invention has a simple structure and is easy to operate. It can comprehensively evaluate the fretting fatigue wear of wire ropes caused by axial loads in actual working conditions. Compared with existing software simulations, it is more practical and more accurate.

[0027] (3) The present invention can comprehensively evaluate the mechanical property damage caused by the fretting fatigue wear of the steel wire rope during the loading process. Compared with the existing research that only explores the fretting fatigue wear between two strands of steel wire rope or the fretting wear between two steel wires, this simulation method is closer to the fretting damage suffered by the steel wire rope in actual application and has practical significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the device of the present invention. DETAILED DESCRIPTION

[0029] The present invention is described in further detail below.

[0030] Example 1

[0031] The present invention provides a wire rope fretting fatigue wear simulation device, comprising a test bench, a control system, and an anchoring device 6 disposed on the test bench for anchoring the wire rope. Loading systems are symmetrically arranged above and below the test bench, and each loading system is equipped with a clamping device for clamping the anchoring device 6. The test bench comprises a base 1, a loading system comprising an upper loading system 9 and a lower loading system 2, symmetrically arranged above and below. The lower loading system 2 is fixed to the base 1, and the upper loading system 9 is fixed to the top beam of the test bench. The clamping device comprises an upper clamp 7 fixed below the upper loading system 9, and a lower clamp 4 fixed above the lower loading system 2. An upper chuck 8 is fixed below the upper clamp 7, and a lower chuck 3 is fixed above the lower clamp 4. The upper clamp 7 and the lower clamp 4, and the upper chuck 8 and the lower clamp 3, are symmetrically arranged above and below. Two anchoring devices 6 are provided, with the upper and lower ends of the wire rope being fixed between the upper clamp 7 and the lower clamp 4, respectively, via one anchoring device 6. The clamps are controlled by the loading system to clamp the anchoring device 6.

[0032] The anchoring device 6 includes a main body, and the steel wire rope to be tested includes a portion 5 that remains in its original state and a portion 14 in which the strands of the steel wire rope are in a dispersed state after the steel wire rope is disassembled. A first cavity and a second cavity are connected through the main body. The first cavity is used to allow the portion 5 of the steel wire rope that remains in its original state to pass through, and the second cavity is used to allow the portion 14 of the steel wire rope that is in a dispersed state of the steel wire rope to pass through. The main body of this embodiment is a bolt 12, specifically a bolt 12 with a stepped hole. A connected cavity is provided from the head of the bolt 12 to the bolt rod, which is a through hole. Moreover, the diameter of the hole at the head of the bolt 12 matches the diameter of the steel wire rope and is frictionless. The diameter of the hole from 1 / 4 of the head of the bolt 12 to the tail of the bolt 12 is twice the diameter of the steel wire rope, that is, the tail of the bolt 12 is expanded to form a stepped hole structure inside the bolt 12. The portion of the wire rope that bears the fatigue load is the portion that remains in its original state. The portion within the stepped hole in the bolt 12 is stripped and filled with epoxy resin fixing glue 13. After curing, the wire rope is anchored. This anchoring device 6 ensures that the load borne by the intact portion of the wire rope between the two bolts 12 during fretting fatigue wear is evenly distributed.

[0033] The control system includes a microcomputer 11 for setting the parameters of the fretting fatigue wear test and a data acquisition system 10. The configurable experimental parameters include load level, fretting load mode, fretting frequency, fretting frequency, data acquisition frequency, etc. The data acquisition system 10 realizes real-time acquisition of fretting times, fretting time, load, and fixture position. The control system can complete the setting of fretting fatigue wear test parameters and data acquisition during the fretting fatigue wear process.

[0034] The method for evaluating the fretting fatigue wear of a steel wire rope using the above-mentioned simulation experimental device for fretting fatigue wear of a steel wire rope comprises the following steps:

[0035] a. Anchor a 7×7 steel wire rope with a diameter of 3.6 mm using an M16×70 bolt 12. The diameters of the stepped holes in the bolts 12 are 4×15 mm, 8×50 mm, and 5 mm, respectively. The tail flare is 5 mm long. The effective length of the steel wire rope is 450 mm.

[0036] b. Assemble the steel wire rope between the upper fixture 7 and the lower fixture 4 through the anchoring device 6, adjust the distance between the upper loading system 9 and the lower loading system 2 so that the steel wire rope is subjected to axial tension on the test bench, and then lock the upper loading system 9;

[0037] c. Set the microcomputer 11 to set the fretting fatigue wear parameters, with the fretting frequencies being 5000, 7500, and 10000 times respectively, and the load mode being set to 0-0.35 ftpk of the impact load condition, and clear the wire rope position and initial load;

[0038] d. Microcomputer 11 controls loading system 2 to axially load / unload the wire rope, and conduct fretting fatigue wear tests according to the set experimental parameters. Data acquisition system 10 collects and records the output signals of different sensors, obtaining the axial displacement of the wire rope under different fretting fatigue wear test parameters and the change in axial tension with the number of loading times.

[0039] e. Repeat steps (ad) to collect output signals from different sensors and record them on the microcomputer 11;

[0040] f. peeling the steel wire rope that has completed the fatigue test under different load conditions in step (e) to observe whether the internal strands are broken after fretting fatigue wear, counting the number of broken wires and broken strands, and measuring the mechanical properties of the intact strands of the stripped steel wire rope;

[0041] Tables 1-4 show that the strand-to-strand mechanical properties of the wire rope gradually deteriorate with the frequency of fretting, and wire breakage occurs after high-frequency fretting fatigue. At 20,000 loading cycles, the center strand breaks, and numerous outer strands break, severely damaging the rope's mechanical properties.

[0042] Table 1 Core strand-surface yarn tensile strength table

[0043]

[0044] Table 2 Tensile strength of surface strands and yarns

[0045]

[0046] Table 3 Surface strand-core wire tensile strength

[0047]

[0048] Table 4 Core strand-core wire tensile strength

[0049] Load times 0 5000 7500 10000 20000 <![CDATA[Tensile strength σ b / MPa]]> 2800 2648 2644 2653 fracture

[0050] Example 2

[0051] a. Anchor a 7×7 steel wire rope with a diameter of 3.6 mm using an M16×70 bolt 12. The diameters of the stepped holes in the bolts 12 are 4×15 mm, 8×50 mm, and 5 mm, respectively. The tail flare is 5 mm long. The effective length of the steel wire rope is 450 mm.

[0052] b. Assemble the steel wire rope between the upper fixture 7 and the lower fixture 4 through the anchoring device 6, adjust the distance between the upper loading system 9 and the lower loading system 2 so that the steel wire rope is subjected to axial tension on the test bench, and then lock the upper loading system 9;

[0053] c. Set the microcomputer 11 to set the fretting fatigue wear parameters, with the fretting frequencies being 5000, 7500, and 10000 times respectively, and the load mode being set to 0-0.45 ftpk of the impact load condition, and clear the wire rope position and initial load;

[0054] d. Microcomputer 11 controls loading system 2 to axially load / unload the wire rope, and conduct fretting fatigue wear tests according to the set experimental parameters. Data acquisition system 10 collects and records the output signals of different sensors, obtaining the axial displacement of the wire rope under different fretting fatigue wear test parameters and the change in axial tension with the number of loading times.

[0055] e. Repeat steps (ad) to collect output signals from different sensors and record them on the microcomputer 11;

[0056] f. peeling the steel wire rope that has completed the fatigue test under different load conditions in step (e) to observe whether the internal strands are broken after fretting fatigue wear, counting the number of broken wires and broken strands, and measuring the mechanical properties of the intact strands of the stripped steel wire rope;

[0057] Combining Tables 5-8 with Example 1, it can be seen that under the same number of loading times, the strand-to-strand tensile strength of the wire rope after the experiment decreased significantly with increasing load value, and as the number of loading times increased, a large number of wires broke, and even strand breakage occurred. Under high load conditions, the number of times the working wire rope can withstand impact loads will drop sharply.

[0058] Table 5 Core-surface yarn tensile strength

[0059]

[0060] Table 6 Tensile strength of strands and yarns

[0061]

[0062] Table 7 Core strand-core wire tensile strength

[0063] Load times 7.5k 5k <![CDATA[Tensile strength σ b / MPa]]> 2418 2471

[0064] Table 8 Surface strand-core wire tensile strength

[0065]

[0066] As can be seen from the above embodiments, the present invention provides a method for simulating the fretting fatigue wear conditions of a wire rope during its service life in actual working conditions and for evaluating the damage to the mechanical properties of the wire rope caused by fretting fatigue wear. The wire rope is fixed using an anchoring device to ensure uniform stress on the wire rope during loading. The anchored wire rope is subjected to fretting fatigue wear loading using a fretting fatigue wear simulation experimental device to simulate the service process of the wire rope. The impact of the fretting fatigue wear of the wire rope on the mechanical properties of the wire rope and the life of the wire rope can be evaluated based on the damage to the mechanical properties of the wire rope after fretting fatigue wear and the damage to the mechanical properties of the strands of the wire rope.

Claims

1. A method for evaluating the wear of a wire rope using a wire rope fretting fatigue wear simulator, characterized in that: The following steps are involved: (A) A length of the original steel wire rope and a length of the steel wire rope in a dispersed strand-filament state are respectively fixed at corresponding positions at the upper and lower ends of the steel wire rope through anchoring devices (6), and then the two anchoring devices (6) are respectively clamped on the clamping device; (B) Adjust the distance between the upper and lower loading systems so that the wire rope is subjected to axial tension on the test bench, and then lock the upper loading system (9); (C) Setting the experimental parameters of fretting fatigue wear through the control system and clearing the position and initial load of the clamping device; (D) The loading system (2) is controlled by the control system to perform axial tensile loading / unloading on the wire rope, and the fretting fatigue wear test is performed according to the set experimental parameters; the control system collects different sensor output signals and records them in the control system to obtain the changes in the axial displacement and axial tension of the wire rope with the number of loading times under different fretting fatigue wear experimental parameters; (E) Repeat steps (A to D) to conduct an orthogonal test on the load level and the number of fretting fatigue wear of the wire rope, collect the output signals of different sensors, and record them in the control system; (F) Conducting mechanical property tests on the steel wire rope that has completed the orthogonal test in step (E); performing calculations, comparisons, and analyses based on the collected data to evaluate the loss of mechanical properties and the life of the steel wire rope after fretting fatigue wear; (G) peeling the steel wire rope after completing the orthogonal test in step (E), observing the breakage of the strands inside the steel wire rope after fretting fatigue wear, counting the number of broken wires and strands, and measuring the mechanical properties of the intact strands after the steel wire rope is peeled; (H) Statistically analyzing the internal strand-wire mechanical properties of the wire rope measured in step (G) to evaluate the fretting fatigue wear of the wire rope under different working conditions and its effect on the mechanical properties of the wire rope.

2. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 1, characterized in that: In step (A), epoxy resin fixing glue (13) is used to pour into the first cavity and the second cavity, and the anchoring of the steel wire rope is completed after solidification.

3. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 1, characterized in that: In step (H), the fretting fatigue wear condition of the wire rope under different working conditions and its influence on the mechanical properties of the wire rope are evaluated based on the number of broken wires, the strand-wire mechanical property damage and the wire rope mechanical property damage.

4. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 1, characterized in that: The wire rope micro-motion fatigue wear simulation device comprises a test bench, a control system, and an anchoring device (6) arranged on the test bench for anchoring the wire rope. Loading systems are symmetrically arranged above and below the test bench, and the two loading systems are respectively provided with clamping devices for clamping the anchoring device (6); the anchoring device (6) comprises a body, and a first cavity and a second cavity are connected to each other through the body. The first cavity is used to allow the portion (5) of the wire rope that maintains its original state to pass through, and the second cavity is used to allow the portion (14) of the wire rope that is in a dispersed state to pass through; the diameter of the first cavity is the same as the diameter of the wire rope, and the diameter of the second cavity is larger than the diameter of the wire rope.

5. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 4, characterized in that: The length of the first cavity is smaller than the length of the second cavity.

6. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 4, characterized in that: The length of the first cavity is 1:3-1:4 of the length of the second cavity.

7. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 4, characterized in that: The diameter of the second cavity is twice the diameter of the steel wire rope.

8. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 4, characterized in that: The body is a bolt, the first cavity extends through the bolt head toward the bolt rod, and the second cavity is arranged in the bolt rod.

9. The method for evaluating the wear of a steel wire rope using a steel wire rope fretting fatigue wear simulator according to claim 4, characterized in that: The clamping device comprises a clamp fixed on the loading system and a clamp fixed on the clamp for clamping the anchoring device (6); the clamp is controlled by the loading system to achieve clamping.

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