A method and system for characterizing the circumferential corrosion state of the cross-section of a lifting sling based on spontaneous magnetic flux leakage

Abstract

The present invention discloses a method and system for characterizing the circumferential corrosion state of the cross-section of a pulling and suspending cable based on spontaneous magnetic leakage, belonging to the field of corrosion damage diagnosis of bridge pulling and suspending cable structures. The present invention is based on the spontaneous magnetic leakage technology and establishes an accurate characterization method for the circumferential corrosion state of the pulling and suspending cable. By monitoring the change of the magnetic induction intensity component B x along the length of the pulling and suspending cable and superimposing and analyzing the B x distribution under different paths, the preliminary identification of the corrosion position is realized. Further, by using the correlation between the B x peak value and its circumferential position, the number and position of the corrosion are accurately quantified. At the same time, through integral and relationship diagram analysis, the circumferential corrosion rate and the central angle are obtained, and then the corrosion depth is evaluated. This method provides a scientific and comprehensive evaluation means for the circumferential corrosion state of in-service pulling and suspending cables, which helps to improve the accuracy and efficiency of structural safety monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion damage diagnosis of bridge stay cables, and more specifically, to a method and system for characterizing the circumferential corrosion state of the cross-section of a stay cable based on spontaneous magnetic leakage. Background Art

[0002] Stay cables are the main load-bearing structures in cable-supported bridges. Under the combined action of complex environments and long-term loading, their sheaths are extremely vulnerable to damage, which increases the probability of damage to the internal steel strands or wire bundles. When damage occurs to the cable body, the ultimate bearing capacity of the bridge will be reduced. Once the damage accumulates to the limit, the service function of the bridge will be destroyed. The damage of the cable mainly occurs on the entire circumference of the long axis and short axis of the cable. Among them, the circumferential damage of the stay cable is of great significance for judging the cable state. Therefore, circumferential non-destructive testing of the cable has great practical application value and scientific significance.

[0003] Spontaneous magnetic leakage testing is a non-destructive testing method proposed by Dubov based on the magnetic memory characteristics of ferromagnetic materials. After years of exploration and research, this technology has been widely used in fields such as mechanical engineering, aerospace, civil engineering, chemical engineering, and petroleum. In civil engineering, this method is often used for stay cables with ferromagnetic characteristics to detect internal damage. Due to environmental reasons, the damage of stay cables often exists in the form of circumferential multi-point corrosion. Existing quantification methods are difficult to quantify relevant states such as the number, location, depth, included angle range, and corrosion rate of circumferential corrosion, and lack corresponding quantification formulas.

[0004] Therefore, how to provide a method and system for characterizing the circumferential corrosion state of the cross-section of a stay cable based on spontaneous magnetic leakage is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method and system for characterizing the circumferential corrosion state of the cross-section of a stay cable based on spontaneous magnetic leakage, which can quantify relevant states such as the number, location, depth, included angle range, and corrosion rate of the circumferential corrosion of the stay cable.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a method for characterizing the circumferential corrosion state of the cross-section of a stay cable based on spontaneous magnetic leakage, including the following steps:

[0008] S1. Obtain the detected value B of the magnetic induction intensity in the x direction of the stay cable by using a magnetic array sensor x , and draw the x-B x distribution broken line graph;

[0009] S2. Along the x direction, for all detection paths, the x-Bx Overlay the broken lines to obtain x - B x-S Overlay graph;

[0010] S3. According to the x - B x-S Overlay graph, obtain the detected value B after overlay x-S The detected value B of the cross - section where the maximum peak is located x-max , and plot the circumferential position θ corresponding to the detected value B of the cross - section where the maximum peak is located x-max and the detected value B of the cross - section where the maximum peak is located x-max into a θ - B x-max broken - line graph;

[0011] S4. According to the θ - B x-max broken - line graph, obtain the number n of single - peak bulges of the broken line, and determine the preliminary number c' of circumferential concentrated corrosion; normalize the slope B x-max between adjacent two points in the θ - B x-max＇ broken - line graph, and determine the accurate number c of circumferential concentrated corrosion according to the relationship between the normalization result and the circumferential position θ;

[0012] S5. Classify and quantify the circumferential concentrated corrosion center θ according to the relationship between the preliminary number c' of circumferential concentrated corrosion and the accurate number c of circumferential concentrated corrosion c ;

[0013] S6. Integrate the θ - B x-max broken - line graph within 0° ≤ θ ≤ 360° to obtain the full - circumference signal integral value B x-maxS value of the sling cross - section, and obtain the circumferential corrosion rate α according to the B x-maxS -α relationship graph;

[0014] S7. Calculate the full - circumference signal integral value B x-maxS of the sling cross - section to obtain the processed value s, determine the processed value l of the circumferential corrosion central angle L according to the s - l relationship graph, and then obtain the circumferential corrosion central angle L according to the inverse formula of the processed value l of the circumferential corrosion central angle L;

[0015] S8. Combine the circumferential corrosion rate α and the circumferential corrosion central angle L to determine the circumferential corrosion depth h.

[0016] Preferably, S3 includes:

[0017] The detected value B of the cross - section where the maximum peak is located x-max and the circumferential position θ corresponding to the detected value B of the cross - section where the maximum peak is located x-max are plotted into a θ - B x-max broken - line graph after 2 - time cycling.

[0018] Preferably, S4 includes:

[0019] S401. Obtain the number \(n\) of single-peak bulges of the broken line according to the distribution characteristics of the broken-line graph shape of \(\theta - B\), and calculate the preliminary circumferential concentrated corrosion number \(c'\) according to the number of single-peak bulges: x-max Among them, \(n\) is the number of single-peak bulges in the \(\theta - B\) broken-line graph;

[0020]

[0021] Among them, \(n\) is the \(\theta - B\) x-max number of single-peak bulges in the broken-line graph;

[0022] S402. Normalize the slope \(B\) between adjacent two points in the \(\theta - B\) broken-line graph to obtain the normalized value \(e\), draw the \(e-\theta\) relationship graph according to the relationship between the normalized value \(e\) and the circumferential position \(\theta\), and calculate the extreme value spacing corresponding to the single-peak bulge in the \(\theta - B\) broken-line graph according to the \(e-\theta\) relationship graph, and calculate the accurate circumferential concentrated corrosion number \(c\): x-max Among them, \(L\) x-max＇ is the extreme value spacing of the \(n\)th single-peak bulge, and \(L\) x-max is the mode value of the extreme value spacing of a single bulge.

[0023]

[0024] Among them, \(L\) n is the extreme value spacing of the \(n\)th single-peak bulge, and \(L\) n-mode is the mode value of the extreme value spacing of a single bulge.

[0025] Preferably, S5 includes:

[0026] S501. Determine the calculation method of the axial concentrated corrosion center according to the relationship between the preliminary circumferential concentrated corrosion number \(c'\) and the accurate circumferential concentrated corrosion number \(c\);

[0027] S502. When \(c = c'\), calculate the circumferential corrosion center \(\theta\) through the corrosion center \(\theta\) where the peak value of the \(\theta - B\) broken-line graph is located: \(\theta\) x-max Among them, \(\theta\) max is the corrosion center \(\theta\) c of the circumferential corrosion; \(\theta\) c =\(\theta\) max

[0028] S503. When \(c\neq c'\), perform Lorentz curve fitting on the \(\theta - B\) broken-line graph, and take the \(\theta\) where the peak value of the Lorentz curve is located x-max as the calculation of the circumferential corrosion center \(\theta\) L The expression for calculating the \(\theta\) where the peak value of the Lorentz curve is located is: c Among them, both \(w\) and \(A\) are fitting parameters of the circumferential corrosion degree and the corrosion included angle range. L The expression for calculating the \(\theta\) where the peak value of the Lorentz curve is located is:

[0029]

[0030] Among them, both \(w\) and \(A\) are fitting parameters of the circumferential corrosion degree and the corrosion included angle range.

[0031] Preferably, for θ-B x-max The calculation formula for integrating the broken line graph is:

[0032]

[0033] The calculation formula for the circumferential corrosion rate α is:

[0034] α = 0.000083·B x-maxS -2.48

[0035] where B x-maxS is the integral value of the full-circumference signal of the cross-section of the lifting sling.

[0036] Preferably, the processing value s of the integral value B of the full-circumference signal of the cross-section of the lifting sling x-maxS has the following calculation formula:

[0037]

[0038] Preferably, the calculation formula for the circumferential corrosion center angle L is:

[0039] L = d·(1 + l) = d·(1 + 4.2s) (0 < s < 1.90)

[0040] where d is the known starting circumferential corrosion center angle.

[0041] Preferably, the calculation formula for the circumferential corrosion depth h is:

[0042]

[0043] In the formula, r is the radius of the specimen.

[0044] On the other hand, the present invention provides a system for characterizing the full-circumference corrosion state of the cross-section of a lifting sling based on spontaneous magnetic leakage, which is used to implement the above-mentioned method for characterizing the full-circumference corrosion state of the cross-section of a lifting sling based on spontaneous magnetic leakage, and includes:

[0045] A magnetic array sensor for obtaining the detected value B of the magnetic induction intensity in the x direction of the lifting sling x ;

[0046] A distribution map generation module for generating an x-B x distribution broken line graph according to the x direction of the lifting sling and the corresponding detected value B x ;

[0047] A superimposing module for superimposing the x-B x broken lines under all detection paths along the x direction to obtain an x-B x-S superimposed graph;

[0048] θ-B x-max A broken line graph generation module for generating a broken line graph based on the x-B x-S The superimposed graph obtains the superimposed detected value B x-S The detected value B of the cross-section where the maximum peak is located x-max and plots the circumferential position θ corresponding to the detected value B of the cross-section where the maximum peak is located x-max against the detected value B of the cross-section where the maximum peak is located x-max as a θ-B x-max broken line graph;

[0049] A circumferential concentration corrosion number determination module for obtaining the number n of single-peak protrusions of the broken line from the θ-B x-max broken line graph and determining the preliminary circumferential concentration corrosion number c'; normalizing the slope B between adjacent points in the θ-B x-max broken line graph and determining the accurate circumferential concentration corrosion number c according to the relationship corresponding to the normalization result and the circumferential position θ; x-max＇

[0050] A circumferential concentration corrosion center determination module for classifying and quantifying the circumferential concentration corrosion center θ according to the relationship between the preliminary circumferential concentration corrosion number c' and the accurate circumferential concentration corrosion number c c ;

[0051] A circumferential corrosion rate calculation module for integrating the θ-B x-max broken line graph within 0° ≤ θ ≤ 360° to obtain the full-circumference signal integration value B of the sling cross-section x-maxS value, and obtaining the circumferential corrosion rate α according to the B x-maxS -α relationship graph;

[0052] A circumferential corrosion central angle calculation module for calculating the full-circumference signal integration value B of the sling cross-section x-maxS to obtain a processed value s, determining the processed value l of the circumferential corrosion central angle L according to the s-l relationship graph, and then obtaining the circumferential corrosion central angle L according to the inverse formula of the processed value l of the circumferential corrosion central angle L;

[0053] A circumferential corrosion depth calculation module for determining the circumferential corrosion depth h by combining the circumferential corrosion rate α and the circumferential corrosion central angle L.

[0054] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method and system for characterizing the full-circumference corrosion state of a sling cross-section based on spontaneous magnetic leakage. Relying on the spontaneous magnetic leakage detection technology, a comprehensive characterization system for the all-round corrosion condition of the sling cross-section is constructed. Specifically, by deeply analyzing the θ-B x-max ​Regarding the distribution characteristics of the line graph, a calculation formula for quantifying the number and position of the corrosion points on the sling is proposed. Further, through the fine processing and analysis of B x-maxS Precise determination methods for the circumferential central angle and corrosion depth of the corrosion area are also realized. Through these characterization formulas, not only the accuracy and efficiency of the assessment of the full-circumference corrosion state of the in-service sling are significantly improved, but also strong technical support and scientific basis are provided for more comprehensively and deeply understanding and dealing with the sling corrosion problem. Brief Description of the Drawings

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0056] Figure 1 It is a flowchart of a method for characterizing the full-circumference corrosion state of the cross-section of a sling based on spontaneous magnetic leakage disclosed by the present invention;

[0057] Figure 2 It is a schematic diagram of each parameter of the full-circumference corrosion state of the sling disclosed by the present invention;

[0058] Figure 3 It is the sling signal B x-max＇ Normalized value e and circumferential position θ correlation model (e-θ diagram);

[0059] Figure 4 It is the circumferential position θ and magnetic leakage signal value B x-max Correlation model (Lorentz fitting curve diagram);

[0060] Figure 5 It is the integral area B x-maxS And corrosion rate α correlation model (B x-maxS-α Diagram);

[0061] Figure 6 It is the signal integral processing value s and circumferential corrosion central angle processing value l correlation model (s-l diagram) disclosed by the present invention. Detailed Embodiments

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0063] An embodiment of the present invention discloses a method for characterizing the circumferential corrosion state of the cross-section of a pulling sling based on spontaneous magnetic leakage, as Figure 1-2 shown, including the following steps:

[0064] S1. Use a magnetic array sensor to obtain the measured value B of the magnetic induction intensity of the pulling sling in the x direction x , and draw an x-B x distribution broken line graph.

[0065] Specifically, the distance between the magnetic array sensor and the surface of the pulling sling remains unchanged all the time. Along the length direction of the pulling sling (x direction), record the x-direction component B of the magnetic induction intensity of the measured pulling sling x , and draw an x-B x distribution broken line.

[0066] When recording, in addition to recording the magnetic induction intensity B in the x direction of the pulling sling x , it is also necessary to record its position and distance information. Among them, the position information is the length position with the straight line where the pulling sling is located as the horizontal coordinate axis, and the distance information is the distance between the magnetic array sensor and the surface of the pulling sling when collecting the magnetic induction intensity B x .

[0067] S2. Along the x direction, superimpose the x-B x broken lines under all detection paths to obtain an x-B x-S superimposed graph.

[0068] S3. According to the x-B x-S superimposed graph, obtain the measured value B of the maximum peak of the superimposed measured value B x-S in the cross-section where the maximum peak is located, and plot the measured value B x-max in the cross-section where the maximum peak is located and the circumferential position θ corresponding to the measured value B x-max in the cross-section where the maximum peak is located into a θ-B x-max broken line graph. x-max

[0069] S4. According to the θ-B x-max broken line graph, obtain the number n of single-peak protrusions of the broken line, and determine the preliminary number c' of circumferential concentrated corrosion; normalize the slopes B x-max between adjacent points in the θ-B x-max＇ broken line graph, and determine the accurate number c of circumferential concentrated corrosion according to the relationship between the normalization result and the circumferential position θ.

[0070] S5. Classify and quantify the circumferential concentrated corrosion center θ c according to the relationship between the preliminary number c' of circumferential concentrated corrosion and the accurate number c of circumferential concentrated corrosion.

[0071] S6. For the θ-B​x-max The broken line graph is integrated within 0° ≤ θ ≤ 360° to obtain the full - circumference signal integral value B of the sling cross - section x-maxS value. According to B x-maxS -α relationship graph, the circumferential corrosion rate α is obtained. The B x-maxS-α relationship graph is drawn based on the corrosion condition of the sling, as Figure 5 shown

[0072] S7. Calculate the full - circumference signal integral value B of the sling cross - section x-maxS to obtain the processed value s. According to the s - l relationship graph, the processed value l of the circumferential corrosion central angle L is determined, and then the circumferential corrosion central angle L is obtained according to the inverse formula of the processed value l of the circumferential corrosion central angle L. Among them, the s - l relationship graph is drawn based on the corrosion condition of the sling

[0073] Through the B x-maxS value of the 2 - 18 - 1# specimen, the B x-maxS values of all specimens are processed to obtain s, and the processed value l of the circumferential corrosion central angle is determined by combining with the "s - l relationship graph". The s - l relationship graph is as Figure 6 shown

[0074] S8. Combine the circumferential corrosion rate α and the circumferential corrosion central angle L to determine the circumferential corrosion depth h

[0075] Further, S3 includes

[0076] The detection value B of the cross - section where the maximum peak is located x-max and the circumferential position θ corresponding to the detection value B of the cross - section where the maximum peak is located x-max are cycled 2 times and then plotted as a θ - B x-max broken line graph

[0077] Further, S4 includes

[0078] S401. According to the distribution characteristics of the shape of the θ - B x-max broken line graph, obtain the number n of single - peak bulges of the broken line, and calculate the preliminary number c' of circumferential concentrated corrosion according to the number of single - peak bulges

[0079]

[0080] Among them, n is the number of single - peak bulges in the θ - B x-max broken line graph

[0081] S402. Normalize the slope B x-max between adjacent two points in the θ - B x-max＇ broken line graph to obtain the normalized value e, and draw the e - θ relationship graph according to the relationship between the normalized value e and the circumferential position θ. The e - θ relationship graph is as Figure 3As shown, calculate according to the e-θ relationship diagram for θ-B x-max For the extreme value spacing corresponding to the single-peak bulge in the line graph, calculate the exact number c of circumferential concentrated corrosion according to the extreme value spacing:

[0082]

[0083] Wherein, L n is the extreme value spacing of the nth single-peak bulge, and L n-mode is the mode value of the extreme value spacing of a single bulge, which is 60.

[0084] Specifically, S5 includes:

[0085] S501. Determine the calculation method of the axial concentrated corrosion center according to the relationship between the preliminary number c' of circumferential concentrated corrosion and the exact number c of circumferential concentrated corrosion;

[0086] S502. When c = c', through the corrosion center θ x-max where the peak of the θ-B max line graph is located, perform the calculation of the circumferential corrosion center θ c : θ c = θ max

[0087] S503. When c ≠ c', perform Lorentz curve fitting on the θ-B x-max line graph. The Lorentz fitting curve graph is as Figure 4 shown. Take the θ L where the peak of the Lorentz curve is located as the circumferential corrosion center θ c for calculation. The expression for calculating the θ L where the peak of the Lorentz curve is located is:

[0088]

[0089] Wherein, both w and A are fitting parameters of the circumferential corrosion degree and the corrosion included angle range.

[0090] Therefore, the piecewise calculation formula for the circumferential corrosion center θ c in S501 is:

[0091]

[0092] In the formula, θ max is the θ corresponding to the peak of B x-max in the θ-B x-max line graph, and θ L is the abscissa corresponding to the peak of the Lorentz fitting curve.

[0093] Furthermore, for the θ-B x-maxThe calculation formula for integrating the line graph is as follows:

[0094]

[0095] The calculation formula for the circumferential corrosion rate α is as follows:

[0096] α = 0.000083·B x-maxS -2.48

[0097] where B x-maxS is the integral value of the full - circumference signal of the cross - section of the tension sling.

[0098] Furthermore, the calculation formula for the processed value s of the integral value B of the full - circumference signal of the cross - section of the tension sling is as follows: x-maxS The calculation formula for the processed value s of the integral value B of the full - circumference signal of the cross - section of the tension sling is as follows:

[0099]

[0100] Furthermore, the calculation formula for the circumferential corrosion central angle L is as follows:

[0101] L = d·(1 + l)=d·(1 + 4.2s)(0 < s < 1.90)

[0102] where s is the processed value of B x-maxS s is restricted by L, and its value range is 0 - 1.90; d is the known starting circumferential corrosion central angle, which is 40, corresponding to the circumferential corrosion central angle of the specimen when N = 2.

[0103] Furthermore, the calculation formula for the circumferential corrosion depth h is as follows:

[0104]

[0105] In the formula, r is the radius of the specimen, which is 7mm.

[0106] On the other hand, the present invention provides a system for characterizing the full - circumference corrosion state of the cross - section of a tension sling based on spontaneous magnetic leakage, which is used to implement the above - mentioned method for characterizing the full - circumference corrosion state of the cross - section of a tension sling based on spontaneous magnetic leakage, including:

[0107] A magnetic array sensor for obtaining the detected value B of the magnetic induction intensity in the x - direction of the tension sling x ;

[0108] A distribution graph generation module for generating an x - B x distribution line graph according to the x - direction of the tension sling and the corresponding detected value B x distribution line graph;

[0109] A superposition module for superposing the x - B x line graphs under all detection paths along the x - direction to obtain an x - B x-S superposition graph;

[0110] θ - B x-max A broken line graph generation module, for generating a broken line graph based on x - B x-S An overlay graph obtains the superimposed detected value B x-S The detected value B of the cross - section where the maximum peak is located x-max , and plots the circumferential position θ corresponding to the detected value B of the cross - section where the maximum peak is located as a θ - B x-max broken line graph with the detected value B of the cross - section where the maximum peak is located x-max ; x-max broken line graph;

[0111] A circumferential concentration corrosion number determination module, for obtaining the number n of single - peak protrusions of the broken line from the θ - B x-max broken line graph and determining the preliminary circumferential concentration corrosion number c'; for the slope B x-max between adjacent two points in the θ - B x-max＇ broken line graph to perform normalization processing, and determine the accurate circumferential concentration corrosion number c according to the relationship corresponding to the normalization result and the circumferential position θ;

[0112] A circumferential concentration corrosion center determination module, for classifying and quantifying the circumferential concentration corrosion center θ according to the relationship between the preliminary circumferential concentration corrosion number c' and the accurate circumferential concentration corrosion number c c ;

[0113] A circumferential corrosion rate calculation module, for integrating the θ - B x-max broken line graph within 0° ≤ θ ≤ 360° to obtain the full - circumference signal integral value B x-maxS of the sling cross - section, and obtaining the circumferential corrosion rate α according to the B x-maxS -α relationship graph drawn based on the corrosion situation of the sling;

[0114] A circumferential corrosion central angle calculation module, for calculating the full - circumference signal integral value B x-maxS of the sling cross - section to obtain a processed value s, determining the processed value l of the circumferential corrosion central angle L according to the s - l relationship graph drawn based on the corrosion situation of the sling, and then obtaining the circumferential corrosion central angle L according to the inverse formula of the processed value l of the circumferential corrosion central angle L;

[0115] A circumferential corrosion depth calculation module, for determining the circumferential corrosion depth h by combining the circumferential corrosion rate α and the circumferential corrosion central angle L.

[0116] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description in the method part.

[0117] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present 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 present invention. Thus, the present invention is not intended 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 characterizing the full-circumference corrosion state of a sling cross section based on spontaneous magnetic leakage, characterized in that: The following steps are involved: S1. Use the magnetic array sensor to obtain the detection value B of the magnetic induction intensity in the x direction of the sling x , and draw xB x Distribution line chart; S2, along the x direction, scan the xB under each sensor path x The polylines are superimposed to obtain xB x-S Overlay graph; S3, according to the xB x-S The overlay image obtains the detection value B after overlay x-S Maximum peak cross-section detection value B x-max , the cross-section detection value B where the maximum peak is located x-max The maximum peak value of the cross section detection value B x-max The corresponding circumferential position θ is plotted as θ-B x-max Line chart; S4, according to the θ-B x-max The number of single peak convexities n of the broken line is obtained from the broken line graph, and the number of preliminary circumferential concentrated corrosion c' is determined; x-max The slope B of two adjacent points in the line graph x-max 'Perform normalization processing, and determine the precise circumferential concentrated corrosion number c according to the relationship between the normalization result and the circumferential position θ; S5. Classify and quantify the circumferential concentrated corrosion center θ according to the relationship between the preliminary circumferential concentrated corrosion number c' and the precise circumferential concentrated corrosion number c. c ; S6, for the θ-B x-max The line graph is integrated within 0°≤θ≤360° to obtain the full-circle signal integral value B of the sling cross section. x-maxS Value, according to B x-maxS -α relationship diagram, the circumferential corrosion rate α is obtained; S7, calculate the full-circle signal integral value B of the cross section of the sling x-maxS Obtaining a processed value s, determining a processed value l of the circumferential corrosion center angle L according to the sl relationship diagram, and then obtaining the circumferential corrosion center angle L according to an inverse formula of the processed value l of the circumferential corrosion center angle L; S8. Determine the circumferential corrosion depth h by combining the circumferential corrosion rate α and the circumferential corrosion center angle L.

2. The method for characterizing the full-circumference corrosion state of a sling cross section based on spontaneous magnetic flux leakage according to claim 1, characterized in that S3 include: The maximum peak cross-sectional detection value B x-max The maximum peak value of the cross section detection value B x-max The corresponding circumferential position θ is plotted as θ-B after two cycles. x-max Line chart.

3. The method for characterizing the full-circumference corrosion state of a cable cross section based on spontaneous magnetic flux leakage according to claim 1, characterized in that S4 include: S401, according to θ-B x-max The distribution characteristics of the broken line graph shape are used to obtain the number n of single-peak protrusions of the broken line, and the preliminary circumferential concentrated corrosion number c' is calculated based on the number of single-peak protrusions: Where n is θ-B x-max The number of unimodal bulges in the line chart; S402, for θ-B x-max The slope B of two adjacent points in the line graph x-max＇ Normalization is performed to obtain a normalized value e, and an e-θ relationship diagram is drawn according to the relationship between the normalized value e and the circumferential position θ. The relationship between θ-B is calculated according to the e-θ relationship diagram. x-max The extreme value spacing corresponding to the single peak bulge in the line graph is used to calculate the precise number of circumferential concentrated corrosion c: Among them, L n is the extreme value spacing of the nth single peak protrusion, L n-mode is the mode value of the distance between the extreme values ​​of a single protrusion.

4. The method for characterizing the full-circumference corrosion state of a cable cross section based on spontaneous magnetic flux leakage according to claim 1, characterized in that S5 include: S501, determining a calculation method for the circumferential concentrated corrosion center according to the relationship between the preliminary circumferential concentrated corrosion number c' and the precise circumferential concentrated corrosion number c; S502, when c = c', through θ-B x-max The peak of the line graph is the corrosion center θ max Circumferential corrosion centerθ c Calculation of: θ c =θ max S503, when c≠c', by x-max The line graph is fitted with the Lorentz curve, and the peak value of the Lorentz curve is taken as θ L is the circumferential corrosion center θ c The calculation is used to calculate the peak of the Lorentz curve θ L The expression is: Among them, w and A are the fitting parameters of the circumferential corrosion degree and corrosion angle range.

5. The method for characterizing the full-circumference corrosion state of a sling cross section based on spontaneous magnetic flux leakage according to claim 1 is characterized in that: For θ-B x-max The calculation formula for the integral of the line chart is: The calculation formula of circumferential corrosion rate α is: α＝0.000083·B x-maxS -2.48 Among them, B x-maxS It is the integral value of the full-circle signal of the cross section of the sling.

6. The method for characterizing the full-circumference corrosion state of a sling cross section based on spontaneous magnetic flux leakage according to claim 1 is characterized in that: The full-circle signal integral value B of the cross section of the sling x-maxS The calculation formula of the processing value s is:

7. The method for characterizing the full-circumference corrosion state of a sling cross section based on spontaneous magnetic flux leakage according to claim 1 is characterized in that: The calculation formula of the circumferential corrosion center angle L is: L=d·(1+l)=d·(1+4.2s)0<s<1.90 Where d is the known starting central angle of circumferential corrosion.

8. The method for characterizing the full-circumference corrosion state of a sling cross section based on spontaneous magnetic flux leakage according to claim 1 is characterized in that: The calculation formula of the circumferential corrosion depth h is: Where r is the radius of the specimen.

9. A system for characterizing the full-circumference corrosion state of a cable cross section based on spontaneous magnetic flux leakage, used to implement a method for characterizing the full-circumference corrosion state of a cable cross section based on spontaneous magnetic flux leakage as described in any one of claims 1 to 8, characterized in that: include: Magnetic array sensor, used to obtain the detection value B of the magnetic induction intensity in the x direction of the sling x ; The distribution map generation module is used to generate the distribution map according to the x direction of the pull rope and the corresponding detection value B x Generate xB x Distribution line chart; The superposition module is used to add xB along all the detection paths in the x direction. x The polylines are superimposed to obtain xB x-S Overlay graph; θ-B x-max A line chart generation module is used to generate a line chart according to the xB x-S The overlay image obtains the detection value B after overlay x-S Detection value B of the cross section where the maximum peak is located x-max , the cross-section detection value B where the maximum peak is located x-max The maximum peak value of the cross section detection value B x-max The corresponding circumferential position θ is plotted as θ-B x-max Line chart; The module for determining the number of circumferential concentrated corrosion is used to determine the number of circumferential concentrated corrosion according to the θ-B x-max The number of single peak convexities n of the broken line is obtained from the broken line graph, and the number of preliminary circumferential concentrated corrosion c' is determined; x-max The slope B of two adjacent points in the line graph x-max＇ Perform normalization processing, and determine the precise circumferential concentrated corrosion number c according to the relationship between the normalization result and the circumferential position θ; A circumferential concentrated corrosion center determination module is used to classify and quantify the circumferential concentrated corrosion center θ according to the relationship between the preliminary circumferential concentrated corrosion number c' and the precise circumferential concentrated corrosion number c c ; Circumferential corrosion rate calculation module, used for the θ-B x-max The line graph is integrated within 0°≤θ≤360° to obtain the full-circle signal integral value B of the sling cross section. x-maxS Value, according to B x-maxS -α relationship diagram, the circumferential corrosion rate α is obtained; The module for calculating the central angle of circumferential corrosion is used to calculate the integral value B of the full-circumference signal of the cross section of the sling. x-maxS A processing value s is obtained, and a processing value l of the circumferential corrosion center angle L is determined according to the sl relationship diagram, and then the circumferential corrosion center angle L is obtained according to the inverse formula of the processing value l of the circumferential corrosion center angle L; a circumferential corrosion depth calculation module is used to determine the circumferential corrosion depth h by combining the circumferential corrosion rate α and the circumferential corrosion center angle L.

Images