Method and device for identifying stress state of corrosion damage pull sling

Abstract

The invention discloses a method and a device for identifying the stress state of a corrosion damage pull sling. Relates to the technical field of bridge detection. The method comprises the following steps: step 1, controlling a stress sensing assembly to move to a preset measuring point along the axial direction of a sling, and establishing a data transmission link; step 2, carrying out low-frequency resonance enhanced force magnetic coupling-based pulling and hoisting cable force identification and high-frequency self-inductance effect pulling and hoisting cable corrosion damage diagnosis by using a transmission link; 3, calculating the stress state of the corrosion damage pull sling according to an identification result and a diagnosis result; and 4, drawing an axial distribution diagram according to the stress state of the corrosion damage pull sling, and marking an abnormal section to obtain an identification result. According to the invention, by adjusting the working coil and the working frequency, the integrated diagnosis of the cable force and the corrosion damage of the pulling and hoisting cable is realized, the problem of alignment of detection results in time and space caused by adopting multiple methods for detection is avoided, and the detection speed and accuracy are improved.

Description

Technical Field

[0001] This invention relates to the field of bridge inspection technology, and more specifically to a method and apparatus for identifying the stress state of corrosion-damaged suspension cables. Background Technology

[0002] In cable-stayed bridges, suspension bridges, and through-arch bridges, the suspenders, as key load-bearing components connecting the main girder to the bridge towers, main cables, or arch ribs, directly affect the overall safety and service performance of the bridge. Under the coupled effects of load and environment, the PE sheath of the suspenders is prone to damage, allowing corrosive media such as air and moisture to penetrate the cable body, causing corrosion damage. Corrosion damage reduces the cross-sectional area of ​​the suspender, leading to increased stress under the same cable force. If the stress exceeds its ultimate tensile strength, it will cause the suspender to break or even cause bridge collapse. Therefore, accurately identifying the stress state of corrosion-damaged suspenders is crucial for ensuring the safe operation of bridges.

[0003] Currently, scholars both domestically and internationally have proposed various methods for identifying cable force by utilizing the sensitivity of the physical parameters of suspension cables to cable force, including the vibration frequency method, the magnetoelastic effect method, and the ultrasonic guided wave method. The vibration frequency method uses technologies such as accelerometers or lidar to measure the natural frequency of the suspension cable, and then inverses the cable force based on the frequency-cable force relationship model. It has the advantages of high efficiency and low cost, but is easily affected by boundary conditions, dampers, and local damage to the suspension cable. The magnetoelastic effect method utilizes the correlation between cable force and permeability in ferromagnetic suspension cables, converting cable force detection into the measurement of electromagnetic parameters to indirectly assess cable force. However, this method is affected by the initial magnetization state of the suspension cable and historical loads, requiring laboratory calibration to establish the electromagnetic parameter-cable force relationship. The ultrasonic guided wave method uses the changes in acoustic characteristics after guided waves propagate in the cable to assess cable force, and can quickly detect the average cable force of the suspension cable. However, the detection results are affected by corrosion damage to the suspension cable.

[0004] Although existing methods for identifying cable stress in bridges have been applied in practice, these methods all assume the cables are undamaged. When determining the stress state of the cables to assess their service condition, they do not consider the cross-sectional loss caused by corrosion damage. This leads to deviations in the stress state assessment from the actual stress state, resulting in inappropriate maintenance measures and threatening the operational safety of the bridge. Therefore, in addition to accurately identifying cable stress, it is also necessary to quantitatively diagnose the changes in cross-sectional area caused by corrosion damage.

[0005] In the diagnosis of corrosion damage in cable-stayed bridges, existing techniques such as ultrasonic guided wave methods and spontaneous magnetic flux leakage methods also have certain limitations. Ultrasonic guided wave methods locate corrosion damage by analyzing characteristics such as wave reflection and mode conversion, but they struggle to quantitatively assess the degree of corrosion damage. Furthermore, the influence of stress state and corrosion damage on the guided wave is difficult to decouple. Spontaneous magnetic flux leakage methods are based on the magnetic flux leakage phenomenon in cable-stayed bridges caused by corrosion damage. This method requires no active excitation and is simple to operate, but it is highly sensitive to environmental electromagnetic interference and cannot yet achieve a quantitative assessment of corrosion damage.

[0006] In summary, the stress state of the suspension cable changes due to the cross-sectional area variation caused by corrosion damage. However, existing methods are unable to simultaneously identify the cable force and the degree of corrosion damage, making it difficult to obtain the true stress state of the suspension cable and to take targeted maintenance measures for the high stress state caused by corrosion damage.

[0007] Therefore, there is an urgent need to develop a method that can simultaneously diagnose the tension and corrosion damage of cable-stayed bridges, so as to accurately identify the stress state of corrosion-damaged cable-stayed bridges and provide practical technical means for the maintenance of cable-stayed bridge systems. Summary of the Invention

[0008] In view of this, the present invention provides a method and device for identifying the stress state of a suspension cable damaged by corrosion. By adjusting the working coil and regulating the working frequency, the integrated diagnosis of cable force and corrosion damage is achieved, avoiding the time and space alignment problems of the detection results caused by using multiple detection methods, and improving the detection speed and accuracy.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a method for identifying the stress state of corrosion-damaged suspension cables, comprising: Step 1: Control the stress sensing component to move along the axial direction of the suspension cable to the preset measuring point and establish a data transmission link; Step 2: Using the transmission link, identify the cable force of the suspension cable based on low-frequency resonant enhanced force-magnetic coupling and diagnose corrosion damage of the suspension cable based on high-frequency self-inductance effect; Step 3: Calculate the stress state of the corrosion-damaged suspension cable based on the identification and diagnosis results; Step 4: Draw an axial distribution diagram based on the stress state of the suspension cable under corrosion damage and mark the abnormal sections to obtain the identification results.

[0010] Preferably, the cable force identification based on low-frequency resonance enhanced force-magnetic coupling in step 2 includes: matching the low-frequency frequency with the initial resonant frequency of the relay coil to generate resonant coupling between the excitation coil and the relay coil, and converting the cable force change into the induced voltage change of the readout coil through the force-magnetic coupling effect to obtain the identification result.

[0011] Preferably, the diagnosis of corrosion damage to the suspension cable due to high-frequency self-inductance effect in step 2 includes: controlling an LCR digital bridge to measure the inductance value of the excitation coil at high frequency, and transmitting the result to a PC terminal via a wireless transmission module to obtain the diagnosis result.

[0012] Preferably, the magnetic permeability of the suspension cable under the identification result is calculated, and combined with the inductance value of the excitation coil, the equivalent radius of the corrosion-damaged suspension cable is deduced, thereby determining the actual cross-sectional area of ​​the suspension cable; according to the principles of mechanics of materials, the actual stress state of the suspension cable at the measuring point is calculated as stress = cable force ÷ actual cross-sectional area.

[0013] Preferably, step 4 specifically includes: plotting an axial distribution diagram of the cable force, equivalent radius, and stress state of the cable with the axial distance of the cable as the abscissa, and automatically marking the sections with severe corrosion or abnormal stress.

[0014] Preferably, a device for identifying the stress state of corrosion-damaged suspension cables includes: a stress identification sensor, a stress identification control system, and a post-processing device connected in sequence. The stress identification sensor includes: a displacement controller, a rigid support, a coil frame, an excitation coil, a relay coil, a readout coil, and a magnetically shielded housing; The stress recognition and control system includes: a signal generator, a power amplifier, an LCR digital bridge, a data acquisition card, a wireless transmission module, and a lithium battery; The post-processing device includes a PC terminal.

[0015] Preferably, the displacement controller is connected to a rigid support, the coil frame is fixedly installed on the rigid support, and the excitation coil, relay coil and readout coil are all tightly wound on the coil frame and the winding direction is the same; the magnetic shielding shell is installed on the outside of the coil and fixed on the rigid support.

[0016] Preferably, the signal generator is connected to the excitation coil via a power amplifier; the LCR digital bridge is connected to the excitation coil; the data acquisition card is connected to the readout coil, the LCR digital bridge, and the wireless transmission module; the wireless transmission module is connected to the PC terminal for communication; and the lithium battery is connected to the displacement controller, the excitation coil, the signal generator, the power amplifier, the LCR digital bridge, the data acquisition card, and the wireless transmission module.

[0017] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method and device for identifying the stress state of corrosion-damaged suspension cables, with the following beneficial effects: (1) Innovative diagnostic method for corrosion damage of suspension cables: The skin effect was first proposed to efficiently adjust the sensitivity of test indicators to cable force and corrosion degree. By measuring the inductance of the excitation coil at high frequency, the sensitivity of the excitation coil inductance to cable force was greatly reduced, while its sensitivity to the cross-sectional area of ​​the corrosion-damaged suspension cable was greatly improved, thus realizing non-destructive quantitative diagnosis of the degree of corrosion damage of suspension cables (i.e., the degree of cross-sectional loss).

[0018] (2) A stress identification method suitable for corrosion-damaged suspension cables is proposed: considering the influence of corrosion damage on the stress caused by the reduction of the cross-sectional area of ​​the suspension cable, the cable force and permeability of the suspension cable are identified by using the low-frequency resonance enhanced force-magnetic coupling effect. On this basis, the degree of cross-sectional damage of the corrosion-damaged suspension cable is quantified by using the high-frequency self-induction effect and the measured permeability. Then, the stress state of the suspension cable is accurately evaluated by combining the cable force and the actual cross-sectional area.

[0019] (3) An integrated diagnostic device for cable stress and corrosion was developed: The core of the cable stress state identification device proposed in this invention is a coil-based sensing system. By adjusting the working coil and regulating the working frequency, the integrated diagnosis of cable stress and corrosion damage of cable is realized, avoiding the problem of time and space alignment of detection results caused by using multiple methods for detection, and improving detection speed and accuracy.

[0020] (4) Applicable to undamaged and corroded slings, it can simultaneously identify the sling tension and the degree of corrosion damage, significantly improving the accuracy of sling stress identification. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 The method flowchart provided by the present invention.

[0023] Figure 2 A flowchart is provided for embodiments of the present invention.

[0024] Figure 3 This is a schematic diagram of the device provided by the present invention.

[0025] Figure 4 This is a schematic diagram of the operation of the device provided by the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 As shown in the figure, an embodiment of the present invention discloses a method for identifying the stress state of corrosion-damaged suspension cables, including: Step 1: Control the stress sensing component to move along the axial direction of the suspension cable to the preset measuring point and establish a data transmission link; Step 2: Using the transmission link, identify the cable force of the suspension cable based on low-frequency resonant enhanced force-magnetic coupling and diagnose corrosion damage of the suspension cable based on high-frequency self-inductance effect; Step 3: Calculate the stress state of the corrosion-damaged suspension cable based on the identification and diagnosis results; Step 4: Draw an axial distribution diagram based on the stress state of the suspension cable under corrosion damage and mark the abnormal sections to obtain the identification results.

[0028] Specifically, step 2, the cable force identification based on low-frequency resonance enhanced force-magnetic coupling, includes: matching the low-frequency frequency with the initial resonant frequency of the relay coil to enable the excitation coil and the relay coil to resonate and couple; and converting the cable force change into the induced voltage change of the readout coil through the force-magnetic coupling effect to obtain the identification result.

[0029] In a specific embodiment of the present invention, when identifying the cable force of the suspension cable, the suspension cable is considered as a non-damaged component with uniform material properties and an intact cross-section. According to Kirchhoff's voltage law, the circuit system consisting of the excitation coil, relay coil, and readout coil can be represented by Equation 1.

[0030] (1) (2) In the formula: U in It is a sinusoidal excitation signal. ω It is the frequency of the sinusoidal excitation signal. I It is the current in the coil. Z This refers to the coil impedance. Subscripts 1, 2, and 3 represent the excitation coil, relay coil, and readout coil, respectively. M 12 (= M 21 ), M 13 (= M 31 ), M23 (= M 32 These are the mutual inductance coefficients between the excitation coil and the relay coil, the excitation coil and the readout coil, and the relay coil and the readout coil, respectively. The impedance of each coil can be determined by Equation 2, where: L , R and C These represent inductance, resistance, and capacitance, respectively, with subscripts... l This refers to a data acquisition card.

[0031] Since the excitation coil and the relay coil are in a resonant coupling state, and the readout coil and the relay coil only form a loosely coupled transformer, the influence of the readout coil on the relay coil can be ignored, that is, it can be considered that... M 23 =M 32 ≈0 Then the induced current of the relay coil can be determined by Equation 3, where k 12 It is the coupling coefficient between the excitation coil and the relay coil.

[0032] Because the distance between the readout coil and the excitation coil is relatively large, and they do not resonate with each other, the influence of the primary coil can be ignored when analyzing the induced voltage in the readout coil; that is, it can be considered that... M 13 =M 32 ≈0 The induced voltage of the readout coil is then determined by equation 4, where... g It is a function. As can be seen from Equations 3 and 4, when the excitation frequency is equal to the sensor's operating frequency (equal to the initial resonant frequency of the relay coil), the excitation coil and the relay coil resonantly couple, and the coupling strength between them, the induced current of the relay coil, and the induced voltage of the readout coil all reach their maximum values.

[0033] (3) (4) The resonant frequency of the relay coil can be determined by Equation 5, that is, the resonant frequency of the relay coil is determined by its inductance and parasitic capacitance. The parasitic capacitance of the relay coil is determined by the coil winding method, while its inductance is related to the suspension cable inside the coil. Since the relay coil and the suspension cable constitute an iron core inductance, the inductance of the relay coil can be expressed by Equation 6.

[0034] (5) (6) In the formula μ It is the initial magnetic permeability of the suspension cable. μ 0 is the permeability of air. Aair20 It is the cross-sectional area of ​​the air gap between the relay coil and the suspension cable. N 2 represents the number of turns in the relay coil.

[0035] Suspension cables are typically made of ferromagnetic materials such as high-strength steel wire or steel strand, so changes in the cable force affect its magnetization state. Due to the force-magnetic coupling effect, there exists a relationship between the cable force and magnetic permeability as shown in Equation 5.

[0036] (7)

[0037] In the formula: F It's Soli. E It is Young's modulus of elasticity. A c0 It is the cross-sectional area of ​​the undamaged sling. K u It is the uniaxial magnetic anisotropy constant. λ s It is the magnetostriction coefficient. M s It is the saturation magnetization. H It is the magnetic field strength. θ It is the angle between the easy magnetization axis of the suspension cable and the magnetic field. Δμ It is the increase in magnetic permeability.

[0038] Substituting Equations 5, 6, and 7 into Equation 4, the correlation between the induced voltage of the readout coil and the tension cable force can be expressed as Equation 8. As can be seen from Equation 8, by utilizing the principle of resonant enhanced force-magnetic coupling and electromagnetic induction, the tension cable force identification can be converted into the measurement of the induced voltage of the readout coil. Based on the establishment of the induced voltage-tension mapping, the tension cable force can be quantitatively evaluated using the induced voltage.

[0039] (8)

[0040] In the formula, h and p are functions.

[0041] Specifically, the diagnosis of corrosion damage to the suspension cable due to high-frequency self-inductance effect in step 2 includes: controlling an LCR digital bridge to measure the inductance value of the excitation coil at high frequency, and transmitting the result to a PC terminal via a wireless transmission module to obtain the diagnosis result.

[0042] In another specific embodiment of the present invention, based on the accurate identification of the cable force, it is necessary to quantify and diagnose the degree of corrosion damage to the cable and determine the cross-sectional area loss of the cable to provide a basis for assessing the stress state of the cable. During corrosion damage diagnosis, the cable and the excitation coil form an iron-core inductor. Under the control of an LCR digital bridge, a high-frequency alternating magnetic field is generated inside the excitation coil. For the cable located in the alternating magnetic field, its internal magnetic flux density accumulates on the cable surface due to the skin effect; the skin depth can be determined by Equation 9. (9)

[0043] In the formula δ It is skin depth, σ e It is electrical conductivity. ω m It is the alternating frequency of the magnetic field.

[0044] To reduce the impact of changes in magnetic permeability caused by variations in the tension of the sling and to improve the sensitivity of the excitation coil's self-inductance to corrosion damage, the excitation coil inductance is measured under high-frequency conditions. In this case, considering the skin effect, the inductance value of the core inductance formed by the excitation coil and the sling can be determined by Equation 10.

[0045] (10)

[0046] In the formula L 1,hf It is the inductance of the excitation coil measured at high frequency. r c It is the equivalent radius of the corrosion-damaged sling corresponding to its actual cross-sectional area. A air1 It is the air gap area inside the excitation coil after corrosion damage to the suspension cable. N 1 represents the number of turns in the excitation coil.

[0047] Equations 6 and 7 show that the magnetic permeability of the suspension cable can be determined based on the induced voltage of the readout coil measured under the cable force identification mode. Combining Equations 9 and 10, when the magnetic permeability, conductivity, measurement frequency, and winding parameters of each coil are determined, the equivalent radius of the corrosion-damaged suspension cable can be determined by the inductance of the excitation coil. The relationship between the two can be expressed as Equation 11, where q is a function. Based on this, the effective cross-sectional area of ​​the corrosion-damaged suspension cable can be determined, and the stress state of the corrosion-damaged suspension cable can be calculated by combining the cable force identification results.

[0048] (11)

[0049] Specifically, the magnetic permeability of the suspension cable under the identification results is calculated, and combined with the inductance value of the excitation coil, the equivalent radius of the corrosion-damaged suspension cable is deduced, thereby determining the actual cross-sectional area of ​​the suspension cable; according to the principles of mechanics of materials, the actual stress state of the suspension cable at the measuring point is calculated as stress = cable force ÷ actual cross-sectional area.

[0050] Specifically, step 4 includes: plotting the axial distribution diagram of cable force, equivalent radius and stress state of the cable with the axial distance of the cable as the abscissa, and automatically marking the sections with severe corrosion or abnormal stress.

[0051] Based on the identification of cable stress and diagnosis of corrosion damage, the stress of the cable under corrosion damage is calculated according to Equation 12 based on the fundamental theory of mechanics of materials. Compared with traditional cable stress identification, this method considers the cross-sectional area damage of the cable caused by corrosion damage, avoiding a serious underestimation of the stress state of the cable under corrosion damage. In addition, based on the identification of the stress state of a single section of the cable, the detection device proposed in this invention can also scan along the axial direction of the cable to obtain a distribution map of the cable stress along its axial direction, thereby intuitively judging the degree of stress anomaly and determining the key control section.

[0052] (12)

[0053] In another specific embodiment of the present invention, such as Figure 2 As shown, the following operating steps are adopted: (1) Assembly and configuration of the device: Based on the aforementioned connection relationship, the displacement controller, rigid support, coil frame, excitation coil, relay coil, readout coil and magnetic shielding shell are assembled to form a stress identification sensor; the signal generator, power amplifier, LCR digital bridge, data acquisition card and wireless transmission module and lithium battery are connected to form a stress identification control system; a PC terminal with dedicated data processing software is used as a post-processing device; the physical and electrical connection between the stress identification sensor, stress identification control system and post-processing device is completed.

[0054] (2) System initialization: Start the stress identification control system and post-processing device, check the working status of each component, and establish a stable communication link.

[0055] (3) Scanning and positioning: The displacement controller drives the stress identification sensor to scan or move to the preset measuring point along the axial direction of the cable according to the predetermined step length.

[0056] (4) Low-frequency pull-down cable force identification: The control signal generator outputs a sinusoidal excitation signal with a frequency equal to the initial resonant frequency of the relay coil. This signal is amplified by the power amplifier and then input into the excitation coil. The data acquisition card measures and reads the induced voltage of the coil and transmits it to the PC terminal through the wireless transmission module.

[0057] (5) High-frequency pull-down cable corrosion damage diagnosis: control the LCR digital bridge to measure the inductance of the excitation coil at high frequency, input the measured inductance value into the data acquisition card, and transmit it to the PC terminal through the wireless transmission module.

[0058] (6) Data Processing and Result Output: Based on the pre-calibrated induced voltage-cable force mapping model, the cable force of the suspension cable is evaluated using the induced voltage of the readout coil, and the permeability of the suspension cable under the current cable force is calculated. Combined with the inductance of the excitation coil measured at high frequency, the equivalent radius of the corrosion-damaged suspension cable is determined, and then the actual stress state of the suspension cable is calculated. On this basis, with the axial distance of the suspension cable as the abscissa, a distribution map of cable force, equivalent radius and stress state of the suspension cable is drawn, and the severely corroded or stress-abnormal sections of the suspension cable are automatically marked.

[0059] Specifically, such as Figure 3 As shown, a device for identifying the stress state of corrosion-damaged suspension cables includes: a stress identification sensor, a stress identification control system, and a post-processing device connected in sequence. The stress identification sensor includes: a displacement controller, a rigid support, a coil frame, an excitation coil, a relay coil, a readout coil, and a magnetically shielded housing; The stress recognition and control system includes: a signal generator, a power amplifier, an LCR digital bridge, a data acquisition card, a wireless transmission module, and a lithium battery; The post-processing device includes a PC terminal.

[0060] Specifically, such as Figure 4 As shown, the displacement controller is connected to a rigid support, the coil frame is fixedly installed on the rigid support, and the excitation coil, relay coil and readout coil are all tightly wound on the coil frame and the winding direction is the same; the magnetic shielding shell is installed on the outside of the coil and fixed on the rigid support.

[0061] Specifically, the signal generator is connected to the excitation coil via a power amplifier; the LCR digital bridge is connected to the excitation coil; the data acquisition card is connected to the readout coil, the LCR digital bridge, and the wireless transmission module; the wireless transmission module communicates with the PC terminal; and the lithium battery is connected to the displacement controller, excitation coil, signal generator, power amplifier, LCR digital bridge, data acquisition card, and wireless transmission module.

[0062] In a specific embodiment of the present invention, the displacement controller is connected to the rigid support and drives the stress identification sensor and the stress identification control system to move with high precision along the axial direction of the cable through its own precise axial displacement, so as to ensure full coverage detection of the entire length of the cable.

[0063] Rigid support: Made of high-strength non-metallic material, it is connected to the coil frame and magnetic shielding shell to provide stable support for the sensor to ensure the stability of its posture and avoid measurement errors caused by its own deformation.

[0064] Coil frame: Made of non-metallic materials such as engineering plastics and epoxy resin, it provides a platform for the excitation coil, relay coil and readout coil.

[0065] Excitation coil: It is formed by tightly winding enameled copper wire on the coil frame. In the cable force recognition mode, the excitation coil acts as an excitation source to excite the relay coil and make it resonate. In the corrosion damage diagnosis mode, the excitation coil works as a self-inductance sensor under the control of the LCR digital bridge.

[0066] Relay coil: It is formed by tightly winding enameled copper wire on the coil frame. The number of turns of the relay coil should be much larger than that of the excitation coil. It is used for cable force identification. Under the action of the excitation signal, it generates a resonant coupling with the excitation coil, which provides a larger excitation magnetic field for the cable, improves the initial magnetization of the cable and reduces the influence of hysteresis effect.

[0067] Readout coil: It is formed by tightly winding enameled copper wire on the coil frame. The number of turns of the readout coil should be on the same order of magnitude as that of the excitation coil, but there should be a large difference. It is used specifically for identifying the cable force of the sling. It forms a loosely coupled transformer with the relay coil to reduce the amplitude of the induced voltage of the relay coil and reduce the performance requirements of the data acquisition card.

[0068] Magnetic shielding shell: Made of electromagnetic shielding materials such as permalloy, reducing the influence of environmental electromagnetic fields or nearby ferromagnetic components.

[0069] Signal generator: capable of providing a sine wave with adjustable amplitude and phase between 10 kHz and 2 MHz, providing a low-frequency excitation signal for cable force identification of the stress identification sensor.

[0070] Power amplifier: capable of amplifying the excitation signal provided by the signal generator, with an amplification factor of 1 to 10 times.

[0071] LCR digital bridge: measures the inductance of the excitation coil, with a test frequency that is steplessly adjustable between 20 Hz and 1 MHz.

[0072] Data acquisition card: When detecting the tension of the sling, it acquires the peak-to-peak value of the induced voltage of the coil; when diagnosing corrosion damage to the sling, it obtains the inductance value of the excitation coil measured by the LCR digital bridge.

[0073] Wireless transmission module: It can communicate with the data acquisition card and PC terminal, and input the data measured by the data acquisition card into the PC terminal for further processing.

[0074] Lithium batteries: power the displacement controller, excitation coil, signal generator, power amplifier, LCR digital bridge, data acquisition card, and wireless transmission module.

[0075] PC terminal: Receives detection data provided by the wireless transmission module. First, it evaluates the cable force based on the peak-to-peak value of the induced voltage of the readout coil measured in the cable force detection mode. Then, it calculates the cross-sectional area of ​​the cable based on the inductance value of the excitation coil measured in the corrosion damage diagnosis mode. Finally, it calculates the actual stress state of the cable at the measuring point by combining the cable force and the cross-sectional area.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for identifying the stress state of a corrosion-damaged stay cable, characterized by, The method comprises the following steps: Step 1: controlling the stress sensing assembly to move axially along the stay cable to a preset measuring point to establish a data transmission link; Step 2: using the transmission link to respectively perform stay cable force identification based on low-frequency resonance enhanced force magnetic coupling and stay cable corrosion damage diagnosis based on high-frequency self-induction effect; Step 3: calculating the stress state of the corrosion-damaged stay cable according to the identification result and the diagnosis result; Step 4: drawing an axial distribution graph and marking abnormal sections according to the stress state of the corrosion-damaged stay cable to obtain the identification result.

2. The method of claim 1, wherein the method is characterized by: The stay cable force identification based on low-frequency resonance enhanced force magnetic coupling in step 2 comprises the following steps: matching the low-frequency frequency with the initial resonance frequency of the relay coil to make the excitation coil and the relay coil resonantly coupled, converting the change of the cable force into the change of the induced voltage of the readout coil through the force magnetic coupling effect, and obtaining the identification result.

3. The method of claim 1, wherein the method further comprises: The stay cable corrosion damage diagnosis based on high-frequency self-induction effect in step 2 comprises the following steps: controlling the LCR digital bridge to measure the inductance value of the excitation coil at high frequency, and transmitting the inductance value to the PC terminal through the wireless transmission module to obtain the diagnosis result.

4. The method of claim 3, wherein the method further comprises: The magnetic permeability of the stay cable under the identification result is calculated, the equivalent radius of the corrosion-damaged stay cable is inversely deduced in combination with the inductance value of the excitation coil, and then the actual cross-sectional area of the stay cable is determined; according to the principle of material mechanics, the actual stress state of the stay cable at the measuring point is calculated according to stress = cable force ÷ actual cross-sectional area.

5. The method of claim 4, wherein the method further comprises: Step 4 specifically comprises the following steps: taking the axial distance of the stay cable as the horizontal coordinate to draw the axial distribution graphs of the stay cable force, the equivalent radius and the stress state, and automatically marking the sections with severe corrosion or abnormal stress.

6. A device for identifying the stress state of a corrosion-damaged stay cable, for carrying out the method according to any one of claims 1 to 5, characterized in that The method comprises the following steps: sequentially connecting a stress identification sensor, a stress identification control system and a post-processing device; the stress identification sensor comprises a displacement controller, a rigid support, a coil framework, an excitation coil, a relay coil, a readout coil and a magnetic shielding shell; the stress identification control system comprises a signal generator, a power amplifier, an LCR digital bridge, a data acquisition card, a wireless transmission module and a lithium battery; the post-processing device comprises a PC terminal.

7. The device for identifying the stress state of a corrosion-damaged pull-in sling according to claim 6, characterized in that The displacement controller is connected with the rigid support, the coil framework is fixedly installed on the rigid support, the excitation coil, the relay coil and the readout coil are densely wound on the coil framework to form the same winding direction, and the magnetic shielding shell is installed outside the coil and fixed on the rigid support.

8. The device for identifying the stress state of a corrosion-damaged tensile cable according to claim 6, characterized in that The signal generator is connected with the excitation coil through the power amplifier; the LCR digital bridge is connected with the excitation coil; the data acquisition card is connected with the readout coil, the LCR digital bridge and the wireless transmission module; the wireless transmission module is in communication connection with the PC terminal; and the lithium battery is connected with the displacement controller, the excitation coil, the signal generator, the power amplifier, the LCR digital bridge, the data acquisition card and the wireless transmission module.

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