On-line monitoring system for fatigue damage of alloy steel wire based on optical fiber sensing

Abstract

This invention discloses an online fatigue damage monitoring system for alloy steel wire based on fiber optic sensing, relating to the field of fatigue damage monitoring. It addresses the problem of ineffective fatigue monitoring of corroded steel wire using fiber optic sensing. The system includes a strain calculation module, a temperature calibration module, a strain analysis module, and a fatigue analysis module. The temperature calibration module calibrates the temperature sensitivity of the intelligent sensor at different temperatures. The strain calculation module calculates the strain at different locations on the surface of the steel wire under test. The strain analysis module analyzes the strain at different locations on the surface of the corroded steel wire, obtaining strain data and analysis data at different locations on the surface of the steel wire under test and the corroded steel wire. The fatigue analysis module analyzes the fatigue condition of the corroded steel wire surface, obtaining different fatigue damage levels of the corroded steel wire. This invention achieves effective fatigue monitoring of corroded steel wire using fiber optic sensing.

Description

Technical Field

[0001] This invention belongs to the field of fatigue damage monitoring technology, specifically an online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing. Background Technology

[0002] Alloy steel wire is widely used in aerospace, energy and power, petrochemical and other fields. It is subjected to the coupled effect of high temperature cyclic load and corrosive environment for a long time, which makes it very easy for fatigue damage to accumulate and eventually lead to sudden fracture. Most existing methods assess fatigue resistance by detecting cracks on the surface of alloy steel wires at different fatigue damage testing stages. Although crack detection can detect fine cracks on the surface of alloy steel wires, due to differences in actual working environments and the poor adaptability of crack detection technology to the environment, some alloy steel wires have been working in photocorrosion environments for a long time, resulting in corrosion on the surface of the alloy steel wires, which affects the detection accuracy of early fine cracks on the surface of alloy steel wires. In contrast, although fiber optic sensors do not rely on visual inspection and have high recognition sensitivity and environmental adaptability, and can accurately identify the strain of different object surfaces in different environments, they cannot currently be effectively used to monitor fatigue of corroded steel wires. Therefore, this invention proposes an online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing. Summary of the Invention

[0003] The purpose of this invention is to propose an online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing, so as to solve the problem mentioned in the background art of the inability to effectively use fiber optic sensing to monitor the fatigue of corroded steel wire.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing includes a data acquisition module, a strain calculation module, a temperature calibration module, a strain analysis module, and a fatigue analysis module. The data acquisition module is used to acquire the initial center wavelength of incident light at different positions on the surface of the steel wire under test and send it to the strain calculation module and the temperature calibration module; the temperature calibration module is used to calibrate the temperature sensitivity of the smart sensor at different temperatures and send it to the strain calculation module. The data acquisition module is also used to acquire the real-time temperature and the real-time center wavelength of the incident light at different locations on the surface of the steel wire to be tested and send them to the strain calculation module; the strain calculation module is used to calculate the strain at different locations on the surface of the steel wire to be tested, calculate the real-time strain at different locations on the surface of the steel wire to be tested and the corroded steel wire after each fatigue damage test and send it to the strain analysis module. The strain analysis module is used to analyze the strain at different locations on the surface of the corroded steel wire, and obtains the strain data and analysis data at different locations on the surface of the steel wire to be tested and the data to be analyzed at different locations on the surface of the corroded steel wire, and sends them to the fatigue analysis module; the fatigue analysis module is used to analyze the fatigue condition of the surface of the corroded steel wire, and obtains different fatigue damage levels of the corroded steel wire.

[0005] Furthermore, the calibration process of the temperature calibration module includes the following: The steel wire to be tested is placed in a variable temperature chamber. The temperature inside the variable temperature chamber is adjusted to a fixed temperature and maintained for a fixed time. Then, the test center wavelength of the incident light at different positions on the surface of the steel wire to be tested is obtained. The different test center wavelengths are added together and the average value is taken to obtain the calibration center wavelength of the incident light at a fixed temperature. Similarly, the temperature inside the variable temperature chamber is adjusted to different temperatures and maintained for a fixed time, and then the calibration center wavelength of the incident light at different temperatures is calculated. A temperature-wavelength coordinate system is constructed with temperature as the horizontal axis and the calibration center wavelength as the vertical axis. The calibration center wavelength of incident light at different temperatures is plotted into the temperature-wavelength coordinate system, thereby obtaining multiple temperature-wavelength coordinate points.

[0006] Furthermore, the calibration process of the temperature calibration module also includes the following: Arbitrarily select a set of adjacent temperature wavelength coordinate points and record them as the first coordinate point and the second coordinate point. Subtract the ordinate of the second coordinate point from the ordinate of the first coordinate point to obtain the first value. Subtract the abscissa of the first coordinate point from the abscissa of the first coordinate point to obtain the second value. Divide the first value by the second value to obtain the slope of the line connecting the first coordinate point and the second coordinate point. Similarly, different adjacent temperature wavelength coordinate points are selected for analysis, and the slope of the line connecting different adjacent temperature wavelength coordinate points is obtained. The average slope of the lines connecting different adjacent temperature wavelength coordinate points in the temperature wavelength coordinate system is obtained by summing the slopes of the lines connecting different temperature wavelength coordinate points in the temperature wavelength coordinate system. The average slope of the line connecting coordinate points of different temperature wavelengths is used as the temperature sensitivity of the smart sensor.

[0007] Furthermore, the calculation process of the strain calculation module includes the following: Select any steel wire to be tested, connect one end of the corresponding steel wire to a wire, then connect the corresponding wire to the positive terminal of the DC power supply, connect the carbon rod to another wire, and then connect the corresponding wire to the negative terminal of the DC power supply. The steel wire and carbon rod to be tested are placed horizontally in the electrolyte solution. The DC power supply is turned on and waited for a fixed time before the DC power supply is turned off. The steel wire to be tested is then removed to complete the chemical corrosion test. The steel wire that has passed the chemical corrosion test is recorded as the corroded steel wire. The corroded steel wire is placed on the test bench and clamped at both ends using a fixing clamp. Then, a fixing pressure is repeatedly applied to the upper fixing clamp to complete a single fatigue damage test on the corroded steel wire.

[0008] Furthermore, the calculation process of the strain calculation module also includes the following: After a single fatigue damage test on the corroded steel wire, any position on the surface of the corroded steel wire is selected as the analysis object. The initial center wavelength and real-time center wavelength of the incident light at the corresponding position are obtained. The real-time wavelength shift of the incident light at the corresponding position is obtained by subtracting the initial center wavelength from the real-time center wavelength. The initial temperature and real-time temperature at the corresponding location of the corroded steel wire are obtained. The temperature offset at the corresponding location is obtained by subtracting the initial temperature from the real-time temperature. The real-time wavelength offset is then subtracted from the product of the temperature sensitivity and the temperature deviation, and divided by the strain sensitivity of the smart sensor to obtain the real-time strain at the corresponding location of the corroded steel wire. Similarly, different locations on the surface of the corroded steel wire are selected as the analysis objects to calculate the real-time strain at different locations on the surface of the corroded steel wire. Multiple fatigue damage tests are then performed on the corroded steel wire to calculate the real-time strain at different locations on the surface of the corroded steel wire after each fatigue damage test. Multiple fatigue damage tests were conducted on several steel wires that had not undergone chemical corrosion testing, and the real-time strain at different locations on the surface of the steel wires was calculated after each fatigue damage test.

[0009] Furthermore, the analysis process of the strain analysis module includes the following: After the first fatigue damage test, the real-time strain at the same position on the surface of different steel wires under test is obtained. The different real-time strains are added together and the average value is taken to obtain the average real-time strain at the corresponding position on the surface of all steel wires under test after the first fatigue damage test. The standard deviation of real-time strain at corresponding positions on the surface of all steel wires under test is calculated using the standard deviation formula. The starting value is obtained by subtracting the standard deviation of real-time strain from the average real-time strain. The ending value is obtained by summing the average real-time strain and the standard deviation of real-time strain. Using the initial value as the left endpoint and the ending value as the right endpoint, a reference strain range is constructed at the corresponding position on the surface of all tested steel wires after the first fatigue damage test. Similarly, the same calculation is performed on the real-time strain at different locations on the surface of the steel wire after each fatigue damage test, and the reference strain range at different locations on the surface of the steel wire after each fatigue damage test is obtained.

[0010] Furthermore, the analysis process of the strain analysis module also includes the following: The real-time strain at different locations on the surface of the corroded steel wire is compared with the right endpoint value of the corresponding reference strain range; If the real-time strain at all locations on the surface of the corroded steel wire is less than or equal to the right end of the corresponding reference strain range, no operation will be performed. If the real-time strain at any location on the surface of the steel wire to be tested is greater than the right end of the reference strain range, then the real-time strain at different locations on the surface of the steel wire to be tested is analyzed to obtain the strain data at different locations on the surface of the steel wire to be tested.

[0011] Furthermore, the analysis process of the strain analysis module also includes the following: A number strain coordinate system is constructed by taking the number of fatigue damage tests as the horizontal axis and the real-time strain at the corresponding position as the vertical axis. Different strain coordinate points are plotted in the number strain coordinate system according to the real-time strain at the analysis position after different fatigue damage tests. Obtain the coordinates of different strain coordinate points, iterate and compare the ordinates of different strain coordinate points to obtain the maximum value of the ordinate, extract the x-coordinate corresponding to the maximum value of the ordinate and record it as the first test number at the corresponding position; Strain polygons are obtained by connecting different strain coordinate points with straight line segments, and the slopes of different strain polygons in the degree strain coordinate system are calculated by the slope formula. By iterating through and comparing the slopes of different strain breaklines, the maximum slope value is obtained, and the strain breakline corresponding to the maximum slope value is recorded as the characteristic breakline. The axonometric mark corresponding to the right endpoint of the characteristic breakline is marked as the second test number at the corresponding position. Similarly, different locations on the surface of the steel wire to be tested are selected as the analysis objects, strain coordinate systems and strain coordinate points of different degrees are constructed, and the first test number and the second test number at different locations are calculated. Different locations on the surface of the corroded steel wire were selected as the analysis objects. A number strain coordinate system and strain coordinate points were constructed. The first number of tests at different locations was obtained and recorded as the first number to be analyzed. The second number of tests at different locations was obtained and recorded as the second number to be analyzed.

[0012] Furthermore, the analysis process of the strain analysis module also includes the following: The average number of first tests at the same location on the surface of different steel wires to be tested is obtained by summing the first test counts at the same location and taking the average value. The average number of second tests at the same location on the surface of different steel wires to be tested is obtained by summing the results and taking the average number of abrupt test results at the corresponding location on the surface of all steel wires to be tested. Similarly, the average number of peak tests at different locations on the surface of all the steel wires under test is calculated, and the average number of abrupt change tests at different locations on the surface of all the steel wires under test is calculated. The average peak test number and the average mutation test number are recorded as strain data at different locations on the surface of the steel wire to be tested; the first number of tests to be analyzed and the second number of tests to be analyzed are recorded as data to be analyzed at different locations on the surface of the corroded steel wire.

[0013] Furthermore, the analysis process of the fatigue analysis module includes the following: The first number of analyses at different locations on the surface of the corroded steel wire was compared with the corresponding average peak number. If the number of first analyses at any location on the surface of the corroded steel wire exceeds the corresponding average peak test number, the fatigue damage level of the corresponding corroded steel wire will be recorded as unqualified. If the first number of analyses at all locations on the surface of the corroded steel wire is less than or equal to the corresponding average peak number, then the second number of analyses at different locations on the surface of the corroded steel wire is compared with the corresponding average number of mutation tests. If the number of second analyses at all locations on the surface of the corroded steel wire is less than or equal to the corresponding average number of mutation tests, then the fatigue damage resistance level of the corresponding corroded steel wire is recorded as a qualified level. If the number of second analyses at any location on the surface of the corroded steel wire exceeds the corresponding average number of mutation tests, the fatigue damage level of the corresponding corroded steel wire will be recorded as unqualified.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention first selects multiple qualified alloy steel wires of the same batch and specifications as the steel wires to be tested, then selects one steel wire to be tested for electrochemical corrosion testing and uses it as the corroded steel wire. Then, the corroded steel wire and different steel wires to be tested are subjected to the same fatigue damage test multiple times. This invention achieves effective fatigue damage testing of corroded steel wires and steel wires to be tested. 2. This invention also calculates the real-time strain at different locations on the surfaces of the corroded steel wire and the steel wire to be tested. Then, based on the calculation results of the real-time strain, it analyzes the strain data at different locations on the surface of the steel wire to be tested and the data to be analyzed at different locations on the surface of the corroded steel wire. Finally, it analyzes the fatigue damage level of the corroded steel wire based on the strain data and the data to be analyzed, thereby effectively using fiber optic sensing to monitor the fatigue damage level of the corroded steel wire. Attached Figure Description

[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is an overall system block diagram of the present invention; Figure 2 This is a wiring diagram for the electrochemical corrosion test in this invention; Figure 3 This is a schematic diagram of the fatigue damage test in this invention; Figure 4 This is a schematic diagram of the number strain coordinate system in this invention; Figure 5 This is a flowchart of the method of the present invention. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1, please refer to Figures 1-4 As shown, the technical solution provided by this invention is as follows: an online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing. Multiple qualified alloy steel wires of the same batch and specification are selected as test wires. Then, one test wire is selected for electrochemical corrosion testing and used as the corroded wire. Next, the same fatigue damage tests are performed multiple times on the corroded wire and different test wires. Then, the real-time strain at different locations on the surfaces of the corroded wire and the test wire is analyzed. The analysis yields strain data at different locations on the surface of the test wire and the data to be analyzed at different locations on the surface of the corroded wire. Finally, the fatigue damage resistance level of the corroded wire is analyzed. The system includes a data acquisition module, a strain calculation module, a temperature calibration module, a strain analysis module, and a fatigue analysis module. In this embodiment, a test light source is connected to a smart sensor. Incident light is emitted into the smart sensor through the test light source. The smart sensor is then attached to the surface of the steel wire to be tested. The smart sensor is an optical fiber sensor with temperature acquisition function. The data acquisition module is used to acquire the initial center wavelength of the incident light at different positions on the surface of the steel wire to be tested, and sends the initial center wavelength of the incident light at different positions to the strain calculation module and the temperature calibration module. In practical implementation, the temperature calibration module is used to calibrate the temperature sensitivity of the smart sensor at different temperatures. The calibration process includes the following: The steel wire to be tested is placed in a variable temperature chamber. The temperature inside the variable temperature chamber is adjusted to a fixed temperature and maintained for a fixed time. Then, the test center wavelength of the incident light at different positions on the surface of the steel wire to be tested is obtained. The different test center wavelengths are added together and the average value is taken to obtain the calibration center wavelength of the incident light at a fixed temperature. Similarly, the temperature inside the variable temperature chamber is adjusted to different temperatures and maintained for a fixed time, and then the calibration center wavelength of the incident light at different temperatures is calculated. A temperature-wavelength coordinate system is constructed with temperature as the horizontal axis and the calibration center wavelength as the vertical axis. The calibration center wavelength of incident light at different temperatures is plotted into the temperature-wavelength coordinate system, thereby obtaining multiple temperature-wavelength coordinate points. Arbitrarily select a set of adjacent temperature wavelength coordinate points and record them as the first coordinate point and the second coordinate point. Subtract the ordinate of the second coordinate point from the ordinate of the first coordinate point to obtain the first value. Subtract the abscissa of the first coordinate point from the abscissa of the first coordinate point to obtain the second value. Divide the first value by the second value to obtain the slope of the line connecting the first coordinate point and the second coordinate point. Similarly, different adjacent temperature wavelength coordinate points are selected for analysis, and the slope of the line connecting different adjacent temperature wavelength coordinate points is obtained. The average slope of the lines connecting different adjacent temperature wavelength coordinate points in the temperature wavelength coordinate system is obtained by summing the slopes of the lines connecting different temperature wavelength coordinate points in the temperature wavelength coordinate system. The average slope of the line connecting the coordinate points of different temperature wavelengths is used as the temperature sensitivity of the smart sensor. It should be explained that the average slope represents the degree of influence of temperature on the calibration center wavelength; In this embodiment, the initial center wavelength and the test center wavelength of the incident light can be obtained through an optical fiber sensor; The temperature calibration module sends the temperature sensitivity of the smart sensor to the strain calculation module.

[0019] In this embodiment, the data acquisition module is also used to acquire the real-time temperature and the real-time center wavelength of the incident light at different locations on the surface of the steel wire to be tested, and send the different real-time temperatures and real-time center wavelengths to the strain calculation module. Specifically, the data acquisition module is an optical fiber sensor with integrated temperature acquisition function. In the specific implementation process, the strain calculation module is used to calculate the strain at different locations on the surface of the steel wire under test based on the real-time temperature and real-time center wavelength. The calculation results are obtained at different locations on the surfaces of the steel wire under test and the corroded steel wire after each fatigue damage test. The calculation process includes the following: Please see Figure 2 As shown, select any steel wire to be tested, connect one end of the corresponding steel wire to a wire, then connect the corresponding wire to the positive terminal of the DC power supply, connect the carbon rod to another wire, and then connect the corresponding wire to the negative terminal of the DC power supply. In this embodiment, the steel wire under test acts as the anode to undergo an oxidation reaction, and the carbon rod acts as the cathode to undergo a reduction reaction; The steel wire and carbon rod to be tested are placed horizontally in the electrolyte solution. The DC power supply is turned on and waited for a fixed time before the DC power supply is turned off. The steel wire to be tested is then removed to complete the chemical corrosion test. The steel wire that has passed the chemical corrosion test is recorded as the corroded steel wire. In this embodiment, the electrolyte solution is a 5% sodium chloride solution; Please see Figure 3 As shown, the corroded steel wire is placed on the test bench and the two ends of the corroded steel wire are clamped with a fixing clamp. Then, the fixing pressure is repeatedly applied to the upper fixing clamp to complete the single fatigue damage test of the corroded steel wire. After a single fatigue damage test on the corroded steel wire, any position on the surface of the corroded steel wire is selected as the analysis object. The initial center wavelength and real-time center wavelength of the incident light at the corresponding position are obtained. The real-time wavelength shift of the incident light at the corresponding position is obtained by subtracting the initial center wavelength from the real-time center wavelength. The initial temperature and real-time temperature at the corresponding location of the corroded steel wire are obtained. The temperature offset at the corresponding location is obtained by subtracting the initial temperature from the real-time temperature. The real-time wavelength offset is then subtracted from the product of the temperature sensitivity and the temperature deviation, and divided by the strain sensitivity of the smart sensor to obtain the real-time strain at the corresponding location of the corroded steel wire. Similarly, different locations on the surface of the corroded steel wire are selected as the analysis objects to calculate the real-time strain at different locations on the surface of the corroded steel wire. Multiple fatigue damage tests are then performed on the corroded steel wire to calculate the real-time strain at different locations on the surface of the corroded steel wire after each fatigue damage test. In the specific implementation process, the strain sensitivity of the smart sensor can be obtained through experiments; Multiple fatigue damage tests were conducted on several steel wires that had not undergone chemical corrosion testing, and the real-time strain at different locations on the surface of the steel wires was calculated after each fatigue damage test. It should be noted that the fatigue damage test of the steel wire to be tested is the same as the fatigue damage test of the corroded steel wire, and will not be repeated here. The strain calculation module sends the real-time strain at different locations on the surface of the steel wire under test and the corroded steel wire after each fatigue damage test to the strain analysis module.

[0020] In this embodiment, the strain analysis module is used to analyze the strain at different locations on the surface of the corroded steel wire based on real-time strain. The analysis process includes the following: After the first fatigue damage test, the real-time strain at the same position on the surface of different steel wires under test is obtained. The different real-time strains are added together and the average value is taken to obtain the average real-time strain at the corresponding position on the surface of all steel wires under test after the first fatigue damage test. The standard deviation of real-time strain at corresponding positions on the surface of all steel wires under test is calculated using the standard deviation formula. The starting value is obtained by subtracting the standard deviation of real-time strain from the average real-time strain. The ending value is obtained by summing the average real-time strain and the standard deviation of real-time strain. Using the initial value as the left endpoint and the ending value as the right endpoint, a reference strain range is constructed at the corresponding position on the surface of all tested steel wires after the first fatigue damage test. Similarly, the same calculation is performed on the real-time strain at different locations on the surface of the steel wire after each fatigue damage test, and the reference strain range at different locations on the surface of the steel wire after each fatigue damage test is obtained. The real-time strain at different locations on the surface of the corroded steel wire is compared with the right endpoint value of the corresponding reference strain range; If the real-time strain at all locations on the surface of the corroded steel wire is less than or equal to the right end of the corresponding reference strain range, no operation will be performed. In the specific implementation process, when the real-time strain at all locations on the surface of the corroded steel wire is less than or equal to the right end value of the corresponding reference strain range, it indicates that the fatigue damage resistance level of the corroded steel wire is qualified. If the real-time strain at any location on the surface of the steel wire to be tested is greater than the right endpoint of the reference strain interval, then the real-time strain at different locations on the surface of the steel wire to be tested is analyzed to obtain strain data at different locations on the surface of the steel wire to be tested. The analysis process includes the following: Please see Figure 4As shown, any position on the surface of the steel wire to be tested is selected as the analysis object. The number of fatigue damage tests is used as the horizontal axis and the real-time strain at the corresponding position is used as the vertical axis to construct a number-strain coordinate system. Based on the real-time strain at the analysis position after different fatigue damage tests, different strain coordinate points are plotted in the number-strain coordinate system. Obtain the coordinates of different strain coordinate points, iterate and compare the ordinates of different strain coordinate points to obtain the maximum value of the ordinate, extract the x-coordinate corresponding to the maximum value of the ordinate and record it as the first test number at the corresponding position; Strain polygons are obtained by connecting different strain coordinate points with straight line segments, and the slopes of different strain polygons in the degree strain coordinate system are calculated by the slope formula. By iterating through and comparing the slopes of different strain breaklines, the maximum slope value is obtained, and the strain breakline corresponding to the maximum slope value is recorded as the characteristic breakline. The axonometric mark corresponding to the right endpoint of the characteristic breakline is marked as the second test number at the corresponding position. Similarly, different locations on the surface of the steel wire to be tested are selected as the analysis objects, strain coordinate systems and strain coordinate points of different degrees are constructed, and the first test number and the second test number at different locations are calculated. Different locations on the surface of the corroded steel wire were selected as the analysis objects. A number strain coordinate system and strain coordinate points were constructed. The first number of tests at different locations was obtained and recorded as the first number to be analyzed. The second number of tests at different locations was obtained and recorded as the second number to be analyzed. In this embodiment, the analysis process for the first and second test counts at different locations on the surface of the corroded steel wire and the steel wire under test is the same, and will not be repeated here. The first test count represents the number of fatigue damages required to reach the maximum strain value at any location on the surface of the steel wire under test, and the second test count represents the number of fatigue damages corresponding to the maximum strain increase at any location on the surface of the steel wire under test. The average number of first tests at the same location on the surface of different steel wires to be tested is obtained by summing the first test counts at the same location and taking the average value. The average number of second tests at the same location on the surface of different steel wires to be tested is obtained by summing the numbers of the second tests at the same location on the surface of all steel wires to be tested and taking the average number of abrupt test results. Similarly, the average number of peak tests at different locations on the surface of all the steel wires under test is calculated, and the average number of abrupt change tests at different locations on the surface of all the steel wires under test is calculated. The average peak test number and the average abrupt change test number are recorded as strain data at different locations on the surface of the steel wire to be tested; the first analysis number and the second analysis number are recorded as analysis data at different locations on the surface of the corroded steel wire. The strain analysis module sends strain data at different locations on the surface of the steel wire to be tested and analysis data at different locations on the surface of the corroded steel wire to the fatigue analysis module.

[0021] In this embodiment, the fatigue analysis module is used to analyze the fatigue condition of the corroded steel wire surface based on strain data and data to be analyzed, and to obtain different fatigue damage levels of the corroded steel wire. The analysis process includes the following: The first number of analyses at different locations on the surface of the corroded steel wire was compared with the corresponding average peak number. If the number of first analyses at any location on the surface of the corroded steel wire exceeds the corresponding average peak test number, the fatigue damage level of the corresponding corroded steel wire will be recorded as unqualified. If the first number of analyses at all locations on the surface of the corroded steel wire is less than or equal to the corresponding average peak number, then the second number of analyses at different locations on the surface of the corroded steel wire is compared with the corresponding average number of mutation tests. If the number of second analyses at all locations on the surface of the corroded steel wire is less than or equal to the corresponding average number of mutation tests, then the fatigue damage resistance level of the corresponding corroded steel wire is recorded as a qualified level. If the number of second analyses at any location on the surface of the corroded steel wire exceeds the corresponding average number of mutation tests, the fatigue damage level of the corresponding corroded steel wire will be recorded as unqualified.

[0022] Example 2, please refer to Figure 5 As shown, based on another concept of the same invention, a method for online monitoring of fatigue damage in alloy steel wire based on fiber optic sensing is proposed, comprising the following steps: Step S101: Calibrate the temperature sensitivity of the smart sensor at different temperatures; Step S102: Calculate the real-time strain at different locations on the surface of the steel wire to be tested based on the real-time temperature and the real-time center wavelength. Step S103: Perform fatigue damage tests on the steel wire to be tested and the corroded steel wire, and construct reference strain ranges at different locations on the surface of the steel wire to be tested based on real-time strain. Step S104: Construct a number strain coordinate system based on real-time strain, and analyze different coordinate points within the number strain coordinate system to obtain strain data at different locations on the surface of the steel wire to be tested and data to be analyzed at different locations on the surface of the corroded steel wire. Step S105: Analyze the fatigue condition of the corroded steel wire surface based on the strain data and the data to be analyzed, and obtain different fatigue damage levels of the corroded steel wire.

[0023] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing, characterized in that, include: The data acquisition module is used to acquire the initial center wavelength of incident light at different positions on the surface of the steel wire under test and send it to the strain calculation module and the temperature calibration module. The temperature calibration module is used to calibrate the temperature sensitivity of the smart sensor at different temperatures and send the calibration data to the strain calculation module. The data acquisition module is also used to collect the real-time temperature and the real-time center wavelength of the incident light at different locations on the surface of the steel wire under test and send them to the strain calculation module. The strain calculation module is used to calculate the strain at different locations on the surface of the steel wire under test, obtain the real-time strain at different locations on the surface of the steel wire under test and the corroded steel wire after each fatigue damage test, and send it to the strain analysis module. The strain analysis module is used to analyze the strain at different locations on the surface of the corroded steel wire, obtain the strain data at different locations on the surface of the steel wire to be tested and the data to be analyzed at different locations on the surface of the corroded steel wire, and send them to the fatigue analysis module. The fatigue analysis module is used to analyze the fatigue condition of the corroded steel wire surface and obtain different fatigue damage levels of the corroded steel wire.

2. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 1, characterized in that, The calibration process of the temperature calibration module includes the following: The steel wire to be tested is placed in a variable temperature chamber. The temperature inside the variable temperature chamber is adjusted to a fixed temperature and maintained for a fixed time. Then, the test center wavelength of the incident light at different positions on the surface of the steel wire to be tested is obtained. The different test center wavelengths are added together and the average value is taken to obtain the calibration center wavelength of the incident light at a fixed temperature. Similarly, the temperature inside the variable temperature chamber is adjusted to different temperatures and maintained for a fixed time, and then the calibration center wavelength of the incident light at different temperatures is calculated. A temperature-wavelength coordinate system is constructed with temperature as the horizontal axis and the calibration center wavelength as the vertical axis. The calibration center wavelength of incident light at different temperatures is plotted into the temperature-wavelength coordinate system, thereby obtaining multiple temperature-wavelength coordinate points.

3. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 2, characterized in that, The calibration process of the temperature calibration module also includes the following: Arbitrarily select a set of adjacent temperature wavelength coordinate points and record them as the first coordinate point and the second coordinate point. Subtract the ordinate of the second coordinate point from the ordinate of the first coordinate point to obtain the first value. Subtract the abscissa of the first coordinate point from the abscissa of the first coordinate point to obtain the second value. Divide the first value by the second value to obtain the slope of the line connecting the first coordinate point and the second coordinate point. Similarly, different adjacent temperature wavelength coordinate points are selected for analysis, and the slope of the line connecting different adjacent temperature wavelength coordinate points is obtained. The average slope of the lines connecting different adjacent temperature wavelength coordinate points in the temperature wavelength coordinate system is obtained by summing the slopes of the lines connecting different temperature wavelength coordinate points in the temperature wavelength coordinate system. The average slope of the line connecting coordinate points of different temperature wavelengths is used as the temperature sensitivity of the smart sensor.

4. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 1, characterized in that, The calculation process of the strain calculation module includes the following: Select any steel wire to be tested, connect one end of the corresponding steel wire to a wire, then connect the corresponding wire to the positive terminal of the DC power supply, connect the carbon rod to another wire, and then connect the corresponding wire to the negative terminal of the DC power supply. The steel wire and carbon rod to be tested are placed horizontally in the electrolyte solution. The DC power supply is turned on and waited for a fixed time before the DC power supply is turned off. The steel wire to be tested is then removed to complete the chemical corrosion test. The steel wire that has passed the chemical corrosion test is recorded as the corroded steel wire. The corroded steel wire is placed on the test bench and clamped at both ends using a fixing clamp. Then, a fixing pressure is repeatedly applied to the upper fixing clamp to complete a single fatigue damage test on the corroded steel wire.

5. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 4, characterized in that, The calculation process of the strain calculation module also includes the following: After a single fatigue damage test on the corroded steel wire, any position on the surface of the corroded steel wire is selected as the analysis object. The initial center wavelength and real-time center wavelength of the incident light at the corresponding position are obtained. The real-time wavelength shift of the incident light at the corresponding position is obtained by subtracting the initial center wavelength from the real-time center wavelength. The initial temperature and real-time temperature at the corresponding location of the corroded steel wire are obtained. The temperature offset at the corresponding location is obtained by subtracting the initial temperature from the real-time temperature. The real-time wavelength offset is then subtracted from the product of the temperature sensitivity and the temperature deviation, and divided by the strain sensitivity of the smart sensor to obtain the real-time strain at the corresponding location of the corroded steel wire. Similarly, different locations on the surface of the corroded steel wire are selected as the analysis objects to calculate the real-time strain at different locations on the surface of the corroded steel wire. Multiple fatigue damage tests are then performed on the corroded steel wire to calculate the real-time strain at different locations on the surface of the corroded steel wire after each fatigue damage test. Multiple fatigue damage tests were conducted on several steel wires that had not undergone chemical corrosion testing, and the real-time strain at different locations on the surface of the steel wires was calculated after each fatigue damage test.

6. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 1, characterized in that, The analysis process of the strain analysis module includes the following: After the first fatigue damage test, the real-time strain at the same position on the surface of different steel wires under test is obtained. The different real-time strains are added together and the average value is taken to obtain the average real-time strain at the corresponding position on the surface of all steel wires under test after the first fatigue damage test. The standard deviation of real-time strain at corresponding positions on the surface of all steel wires under test is calculated using the standard deviation formula. The starting value is obtained by subtracting the standard deviation of real-time strain from the average real-time strain. The ending value is obtained by summing the average real-time strain and the standard deviation of real-time strain. Using the initial value as the left endpoint and the ending value as the right endpoint, a reference strain range is constructed at the corresponding position on the surface of all tested steel wires after the first fatigue damage test. Similarly, the same calculation is performed on the real-time strain at different locations on the surface of the steel wire after each fatigue damage test, and the reference strain range at different locations on the surface of the steel wire after each fatigue damage test is obtained.

7. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 6, characterized in that, The analysis process of the strain analysis module also includes the following: The real-time strain at different locations on the surface of the corroded steel wire is compared with the right endpoint value of the corresponding reference strain range; If the real-time strain at all locations on the surface of the corroded steel wire is less than or equal to the right end of the corresponding reference strain range, no operation will be performed. If the real-time strain at any location on the surface of the steel wire to be tested is greater than the right end of the reference strain range, then the real-time strain at different locations on the surface of the steel wire to be tested is analyzed to obtain the strain data at different locations on the surface of the steel wire to be tested.

8. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 7, characterized in that, The analysis process of the strain analysis module also includes the following: A number strain coordinate system is constructed by taking the number of fatigue damage tests as the horizontal axis and the real-time strain at the corresponding position as the vertical axis. Different strain coordinate points are plotted in the number strain coordinate system according to the real-time strain at the analysis position after different fatigue damage tests. Obtain the coordinates of different strain coordinate points, iterate and compare the ordinates of different strain coordinate points to obtain the maximum value of the ordinate, extract the x-coordinate corresponding to the maximum value of the ordinate and record it as the first test number at the corresponding position; Strain polygons are obtained by connecting different strain coordinate points with straight line segments, and the slopes of different strain polygons in the degree strain coordinate system are calculated by the slope formula. By iterating through and comparing the slopes of different strain breaklines, the maximum slope value is obtained, and the strain breakline corresponding to the maximum slope value is recorded as the characteristic breakline. The axonometric mark corresponding to the right endpoint of the characteristic breakline is marked as the second test number at the corresponding position. Similarly, different locations on the surface of the steel wire to be tested are selected as the analysis objects, strain coordinate systems and strain coordinate points of different degrees are constructed, and the first test number and the second test number at different locations are calculated. Different locations on the surface of the corroded steel wire were selected as the analysis objects. A number strain coordinate system and strain coordinate points were constructed. The first number of tests at different locations was obtained and recorded as the first number to be analyzed. The second number of tests at different locations was obtained and recorded as the second number to be analyzed.

9. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 8, characterized in that, The analysis process of the strain analysis module also includes the following: The average number of first tests at the same location on the surface of different steel wires to be tested is obtained by summing the first test counts at the same location and taking the average value. The average number of second tests at the same location on the surface of different steel wires to be tested is obtained by summing the results and taking the average number of abrupt test results at the corresponding location on the surface of all steel wires to be tested. Similarly, the average number of peak tests at different locations on the surface of all the steel wires under test is calculated, and the average number of abrupt change tests at different locations on the surface of all the steel wires under test is calculated. The average peak test number and the average mutation test number are recorded as strain data at different locations on the surface of the steel wire to be tested; the first number of tests to be analyzed and the second number of tests to be analyzed are recorded as data to be analyzed at different locations on the surface of the corroded steel wire.

10. The online monitoring system for fatigue damage of alloy steel wire based on fiber optic sensing according to claim 1, characterized in that, The analysis process of the fatigue analysis module includes the following: The first number of analyses at different locations on the surface of the corroded steel wire was compared with the corresponding average peak number. If the number of first analyses at any location on the surface of the corroded steel wire exceeds the corresponding average peak test number, the fatigue damage level of the corresponding corroded steel wire will be recorded as unqualified. If the first number of analyses at all locations on the surface of the corroded steel wire is less than or equal to the corresponding average peak number, then the second number of analyses at different locations on the surface of the corroded steel wire is compared with the corresponding average number of mutation tests. If the number of second analyses at all locations on the surface of the corroded steel wire is less than or equal to the corresponding average number of mutation tests, then the fatigue damage resistance level of the corresponding corroded steel wire is recorded as a qualified level. If the number of second analyses at any location on the surface of the corroded steel wire exceeds the corresponding average number of mutation tests, the fatigue damage level of the corresponding corroded steel wire will be recorded as unqualified.

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