A method of testing a rail for fracture

Abstract

The present application provides a kind of rail fracture test method, comprising the following steps: step one: through the vibration sensor of vehicle running part axle box end, collect the vibration displacement of vehicle running part to steel rail;Step two: vibration sensor converts the collected mechanical vibration displacement into electrical signal, and is transmitted to the signal acquisition instrument of test equipment;Step three: signal processing unit is calculated and deduced to the deflection deformation of steel rail by formula through mechanics principle;Step four: the bending stiffness of the section steel rail is calculated by formula;Step five: test equipment is further calculated according to the collected deflection displacement data and bending stiffness data of steel rail The vertical vibration displacement and change rate of steel rail are calculated by formula;Step six: test equipment will automatically complete the detection, analysis and judgment of steel rail according to the obtained data;Solve the problem that user needs to manually operate and identify when testing by traditional flaw detection vehicle, without special arrangement of skylight time for testing, improve the efficiency of testing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of track detection, more particularly relates to a steel rail fracture testing method. BACKGROUND

[0002] With the development of railway transportation, steel rails are an important part of railway transportation, providing a support, running and guiding surface for train wheels, and maintaining the integrity of steel rails is a necessary condition to ensure the safe operation of trains. However, under the load of the train, the steel rail will inevitably be damaged in various ways, of which the steel rail fracture is the most serious damage affecting the safety of train operation and must be discovered and disposed of in a timely manner.

[0003] For example, the Chinese utility model patent with patent number 202321351872.3 provides a steel rail damage detection mechanism and a steel rail flaw detection vehicle. The steel rail flaw detection vehicle is provided with a traction vehicle and a detection vehicle. When in use, the detection vehicle is pulled by the power running part of the traction vehicle. The detection vehicle performs ultrasonic detection and electromagnetic detection on the steel rail through the electromagnetic probe mechanism and the ultrasonic probe mechanism, thereby improving the accuracy of detection. However, the traditional flaw detection trolley has certain limitations. It needs to be placed on the steel rail during the line window period and then detected. It also needs to be manually operated by the user. It cannot realize the normalization monitoring of the steel rail and reduces the detection efficiency. SUMMARY

[0004] To solve the above technical problems, the present application provides a steel rail fracture testing method to solve the technical problem that the traditional flaw detection vehicle needs to be manually operated by the user and placed on the steel rail during the line window period, which cannot realize the normalization monitoring of the steel rail and reduces the detection efficiency.

[0005] The purpose and effect of the steel rail fracture testing method of the present application are achieved by the following specific technical means:

[0006] A steel rail fracture testing method, comprising a steel rail and a train, wherein the train comprises a vehicle running part, the top of the steel rail is in contact with the vehicle running part, vibration sensors are arranged at both ends of the vehicle running part axle box, a carriage is arranged at the top of the vehicle running part, a test device is arranged in the carriage, and two groups of vibration sensors are electrically connected to the test device.

[0007] The test method comprises the following steps:

[0008] Step 1: When the train runs on the steel rail, the vehicle running part wheels will exert a load on the steel rail to produce vibration and displacement. The vibration sensors installed at the ends of the vehicle running part axle box will collect the vibration displacement exerted by the vehicle running part on the steel rail.

[0009] Step two: the vibration sensor can convert the collected mechanical vibration displacement into an electrical signal, and a data line or a wireless connection is adopted between the vibration sensor and the test equipment, the test equipment includes a signal acquisition analyzer, the vibration sensor converts the electrical signal obtained by the displacement into the signal acquisition analyzer through the connecting line, the signal acquisition analyzer collects, amplifies and encodes the electrical signal input from each channel, and then transmits the signal to the signal processing unit in the test equipment;

[0010] Step three: the signal processing unit calculates and deduces the deflection deformation of the steel rail by the mechanical principle that the steel rail will produce deflection deformation when subjected to load;

[0011] Step four: the stiffness of each section of the steel rail is different, so the formula is needed to calculate the numerical value of the bending stiffness of the steel rail;

[0012] Step five: the test equipment can further calculate the vertical vibration displacement of the steel rail according to the collected deflection displacement data and bending stiffness data of the steel rail through the formula;

[0013] Step six: after obtaining the vertical vibration displacement of the steel rail through steps one to five, the test equipment analyzes the obtained data to automatically complete the detection and judgment of the steel rail, and completes the detection of the steel rail.

[0014] As a further scheme of the application, in step three, the deduced formula is: Wherein, u represents the deflection displacement of the steel rail, E represents the elastic modulus of the steel rail, I represents the moment of inertia of the steel rail, represents the vertical vibration displacement of the steel rail.

[0015] As a further scheme of the application, in step three, when the steel rail is fractured or damaged, the moment of inertia I decreases, the vertical displacement increases, and by comparing the deflection deformation of the steel rail under the same dynamic action with the normal value, the integrity of the steel rail can be preliminarily inferred.

[0016] As a further scheme of the application, in step four, the formula is a bending stiffness formula, which is based on the material of the steel rail to calculate the bending stiffness of the steel rail, the bending stiffness represents the resistance of the steel rail to bending deformation, therefore, under the same external bending moment, when the bending stiffness is larger, the deflection deformation of the steel rail will decrease, and the ability to resist bending deformation is stronger.

[0017] As a further scheme of the application, the bending stiffness formula is: Wherein, k represents the bending stiffness of the steel rail, u represents the deflection displacement of the steel rail, E represents the elastic modulus of the steel rail, the represents the vertical inertia moment of the steel rail.

[0018] As a further scheme of the present application, in step five, the formula is a deflection deformation equation, and the general solution of the differential equation of the formula is: And the steel rail is rigidly fixed on the line, and has a constraint condition, so that the calculation conforms to the actual use, and therefore the deflection deformation equation is: Wherein, represents the vertical vibration displacement of the steel rail, k represents the bending stiffness of the steel rail, and u represents the deflection displacement of the steel rail.

[0019] As a further scheme of the present application, in step six, when the displacement change calculated by the test equipment is less than 10% of the standard value, the steel rail does not need to be concerned.

[0020] As a further scheme of the present application, in step six, when the displacement change calculated by the test equipment is 10% to 30% of the standard value, the test equipment will retrieve the historical data of the steel rail for comparison, and mark it.

[0021] As a further scheme of the present application, when the displacement change of the marked steel rail continues to increase and reaches or is greater than 30% of the standard value, the test equipment will perform waveform analysis on the marked steel rail, and then issue a rail breakage warning.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1. Compared with the prior art, by setting the test equipment on a conventional operating train, and through the signal acquisition instrument and the signal processing unit of the test equipment, the data is automatically collected and recorded and analyzed, the problem of manual operation of the traditional flaw detection vehicle detection is solved, special sky window time is not needed for testing, the whole process does not need manual operation, labor cost is saved, real-time monitoring is realized, problems are found in time and alarm is given, and detection efficiency is improved.

[0024] 2. By setting the vibration sensor and the vehicle running part, when the test method is used, the vibration displacement data of the steel rail can be collected by the vibration sensor to provide data input for subsequent calculation, and then the deflection displacement, the bending stiffness and the vertical vibration displacement of the steel rail are calculated by using the formula; then the integrity of the steel rail is judged according to the displacement change, when the displacement change reaches a certain degree, it is judged that the steel rail is damaged and needs to be concerned and repaired; the test method avoids the trouble of manual inspection, can monitor the condition of the steel rail in real time, and effectively improves the safety.

[0025] 3. Through the setting of the threshold, when using the test method, the rail parameters are obtained by a theoretical calculation formula, and compared with the standard value, the health status of the rail can be accurately judged; if the displacement change is within 10%, the rail is normal; between 10-30%, attention is needed; more than 30% is judged to be damaged, and needs to be repaired; this quantitative judgment can minimize the probability of false positives, and improve the accuracy of the test results. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a calculation flowchart of the rail fracture test method of the present application;

[0027] Figure 2 is a schematic diagram of the increase of the vertical displacement of the rail caused by the crack in the rail fracture test method of the present application;

[0028] Figure 3 is a schematic diagram of the change trend of the vertical displacement y(x) and the moment of inertia I of the rail fracture test method of the present application. DETAILED DESCRIPTION

[0029] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with the drawings and examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present application, and are not a limitation on the claims of the present application.

[0030] Example: the test method includes the following steps:

[0031] Step 1: When the train is running on the rail, the wheels of the vehicle running part will produce vibration and exert displacement force on the rail, and the wheels of the vehicle running part are in direct contact with the rail, and the wheels will cause the rail to produce flexural deformation when rolling; in order to collect this flexural deformation, vibration sensors are installed at both ends of the axle box of the vehicle running part, and the vibration will be transmitted to the vibration sensor through the vehicle running part, and the vibration sensor can detect the mechanical vibration and displacement exerted by the wheels of the vehicle running part on the rail in real time, avoiding the trouble of manually checking the rail, improving the detection efficiency and safety;

[0032] Step two: the vibration sensor can detect the mechanical vibration displacement of the rail and convert it into corresponding electrical signals, which are collected and processed through the connecting line between the vibration sensor and the test equipment, or through wireless signal transmission. The test equipment contains a signal acquisition instrument for collecting, amplifying and coding the electrical signals output by the vibration sensor. The electrical signals output by the vibration sensor are transmitted to the signal acquisition instrument through the connecting line. The signal acquisition instrument has multiple signal input ports and can simultaneously collect the output signals of multiple vibration sensors. The signal acquisition instrument first filters and amplifies the input electrical signals to eliminate interference signals, then encodes the signals, and then sends the encoded digital signals to the signal processing unit in the test equipment, realizing the collection, transmission, processing and analysis of the rail mechanical vibration displacement signals.

[0033] Step three: the signal processing unit contains the material parameters and mechanical calculation model of the rail. When the train is running, the external force exerted by the wheel on the rail will cause the rail to deflect and deform. The signal processing unit can calculate the theoretical deflection and deformation of the rail under the external force according to the input rail parameters, using mechanical principles and related formulas, to ensure detection accuracy and reliability.

[0034] Step four: the stiffness of the rail refers to the ability of the rail to resist deformation, which is related to the material properties and structural geometry of the rail. Due to the long length of the rail, local deformation may occur during laying and use, resulting in differences in the stiffness of each section of the rail. If these differences are not considered and a unified theoretical calculation model is used, it may lead to errors in the detection results. Therefore, in order to improve the detection accuracy, the signal processing unit needs to calculate the stiffness of different sections of the rail when calculating the theoretical deflection and deformation, and obtain the bending stiffness value of each section of the rail. Then, the actual stress is substituted into the calculation model of the corresponding section to obtain a more accurate theoretical deflection and deformation. The rail is calculated by the formula to further improve the accuracy of the calculation results.

[0035] Step five: during the detection of the rail, the test equipment not only collects the deflection and deformation data of the rail, but also obtains the bending stiffness values of different sections of the rail. The test equipment can calculate the vertical vibration displacement of the rail according to the input deflection and deformation data and bending stiffness data through the formula. If the actual deflection and deformation exceeds a certain range of the theoretical calculation value, it indicates that there is abnormal vibration displacement, which may be caused by structural damage.

[0036] Step six: through the foregoing steps, the test equipment obtains the displacement change of the vertical vibration position of different sections of the rail, and compares it with the threshold value to determine whether the structure of the rail is complete, and completes the detection of the rail; the test equipment also compares the test data with historical data to avoid false positives as much as possible, and also monitors the long-term state of the rail through big data analysis to improve detection accuracy. This method can provide strong protection for ensuring the safety of railway operation.

[0037] wherein the derivation formula in step three is: wherein u represents the deflection displacement of the rail, E represents the elastic modulus of the rail, I represents the moment of inertia of the rail, represents the vertical vibration displacement of the rail, and the test equipment can calculate the theoretical deflection displacement of the rail by using the derivation formula, thereby providing a basis for judging the structural integrity. Selecting the bending stiffness of the corresponding section can improve the calculation accuracy and make the result more accurately reflect the actual state of the rail.

[0038] wherein, as shown in Figure 3 When the rail is broken or damaged, the cross-sectional size and the moment of inertia I decrease, and under the same external force, the decreased cross-sectional size and the moment of inertia I will cause the stiffness of the structure to decrease, resulting in increased deflection deformation and vibration displacement. When the test equipment detects the rail, it will select the same detection conditions and the same dynamic action, collect the deflection displacement data of the rail, and then compare the collected data with the theoretical calculation value or historical data under the normal state. If the collected data is significantly greater than the normal value, it indicates that under the same external force, the deformation of the rail increases, the structural stiffness decreases, and it is likely that the decrease in the cross-sectional size or the moment of inertia I is caused, which means that the structure of the rail may be damaged or broken and needs to be paid attention to. If the difference between the collected data and the normal value is within the allowable range, it indicates that the structure of the rail is complete; under the same dynamic action, the deformation response of the structure does not change significantly, indicating that the cross-sectional size and the moment of inertia I have not decreased, and the structural stiffness has not decreased. This can preliminarily determine the structural integrity of the rail and does not need to be paid attention to. Therefore, the test equipment adopts the method of detecting the rail multiple times under the same detection conditions and dynamic action and comparing it with the normal value, which can effectively determine the structural integrity of the rail and provide protection for railway safety.

[0039] wherein, as shown in Figure 2As shown in FIG. 4, in step four, the formula is a bending stiffness formula, the bending stiffness represents the resistance of the rail to bending deformation, the greater the value, the stronger the resistance to bending deformation, under the same external bending moment, the greater the bending stiffness, the smaller the deflection deformation of the rail, and the stronger the resistance to bending deformation; the test equipment can calculate the theoretical bending stiffness of different sections according to the material and cross-sectional size of the rail, if the deflection deformation of the rail is greater than the theoretical calculation value under the same external bending moment, it indicates that the bending stiffness of the section may decrease, and the resistance to deformation is weakened, which may be due to the crack on the rail, and the vertical displacement caused by the crack has a specific steady-state waveform shape, therefore, the test equipment can compare the steady-state waveform shape of the rail with the theoretical calculation value to determine whether the bending stiffness of different sections of the rail changes, this method can avoid the error of single detection result and improve the accuracy of judgment.

[0040] The bending stiffness formula is: Wherein, k represents the bending stiffness of the rail, the greater the bending stiffness, the stronger the resistance of the rail to bending deformation; u represents the deflection displacement of the rail, the greater the bending stiffness k, the smaller the deflection displacement u under the same external force; E represents the elastic modulus of the rail, the greater the elastic modulus, the higher the stiffness of the material, and the stronger the resistance to deformation; I represents the vertical inertia moment of the rail, the greater the inertia moment, the stronger the resistance of the cross section to bending deformation; therefore, according to the bending stiffness formula, it can be known that the bending stiffness k of the rail is positively correlated with the elastic modulus E and the inertia moment I; the greater the elastic modulus E and the inertia moment I, the higher the bending stiffness k, and the stronger the resistance of the rail to bending deformation.

[0041] Wherein, please refer to FIG. 5, Figure 3 As shown in FIG. 5, in step five, the formula is a deflection deformation equation, the general solution of the differential equation of the equation is: However, the rail is rigidly fixed on the line, and has a constraint condition, in order to make the calculation conform to the actual use, the test equipment adopts the following deflection deformation equation: Wherein, The vertical vibration displacement of the rail is represented by k, and the deflection displacement of the rail is represented by u. According to the equation, the change of the vertical displacement of the rail from the crack is a 3rd order exponential change process; by using the calculation of the deflection deformation equation, the crack propagation ratio and the displacement change ratio relationship are obtained, it can be obtained that in the initial stage of the crack, the vertical displacement change is not large, with the increase of the crack propagation, the displacement change also gradually increases, and the sensitivity increases.

[0042] In step six, when the test device calculates that the displacement change of the rail is 10% of the standard value, it indicates that the deflection deformation of the rail is small, and the ability to resist bending deformation is strong, so the rail does not need to be concerned; this also means that the bending stiffness of the rail is large, and can withstand the action of the same external bending moment, thereby reducing the deflection deformation it produces; wherein, due to the influence of various factors in the track line, the stiffness of the rail at each position will be different, and the standard value represents the value when the rail at the same position is intact. In actual use, the test device will automatically judge the integrity of the rail according to the calculated displacement change, and perform corresponding processing and warning, thereby ensuring the safety of train travel.

[0043] In step six, when the test device calculates that the displacement change of the rail is 10% to 30% of the standard value, the test device will take further measures to evaluate the condition of the rail; in order to more accurately judge the health status of the rail, the test device will retrieve the historical data of the rail for comparative analysis; through comparison with the historical data, the test device can detect whether there are potential problems or abnormal changes in the rail; at the same time, the test device will mark these rails with potential problems for subsequent monitoring and maintenance, and can also remind relevant personnel to observe and pay more attention to these rails, and take necessary repair or replacement measures; through timely marking and processing, the risk of rail failure and fracture can be effectively prevented and reduced, ensuring the safety and reliability of railway transportation.

[0044] When the displacement change of the marked rail continues to increase and reaches or is greater than 30% of the standard value, the test device will perform waveform analysis on the marked rail; through waveform analysis on the marked rail, the test device can further understand the vibration characteristics and deformation mode of the rail, and refer to Figure 2 the rail displacement change test and waveform analysis to identify rail cracking from multiple angles, which can more accurately predict rail fracture; when the rail cracks, the vertical displacement increases, indicating that the moment of inertia I decreases, so the rail may have cracked; once the test device confirms through waveform analysis that there is a risk of rail fracture, it will immediately issue a warning signal of rail fracture; this warning signal will be sent to relevant maintenance personnel or monitoring systems, so that they can immediately take appropriate emergency measures, such as limiting train speed, emergency repair or replacing damaged rails, to ensure the safety of train travel.

[0045] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method of testing a rail for fracture, characterised by: It includes the following steps: Step 1: When the train travels on the rails, the wheels of the vehicle's running gear will exert vibration and displacement on the rails. Vibration sensors are installed at both ends of the axle boxes of the vehicle's running gear to collect the vibration and displacement exerted by the vehicle's running gear on the rails. Step 2: The vibration sensor can convert the collected mechanical vibration displacement into an electrical signal. A testing and analysis device is installed on the train, and the vibration sensor and the testing device are connected by a data cable or wirelessly. The testing device includes a signal acquisition and analysis instrument. The vibration sensor transmits the converted electrical signal to the signal acquisition instrument through the connecting cable. The signal acquisition instrument collects, amplifies, and analyzes the input electrical signals and then transmits them to the signal processing unit in the testing device. Step 3: The signal processing unit uses the mechanical principle that the rail will flex when subjected to load to calculate and derive the flexural deformation of the rail and its variation law using formulas. Step 4: The stiffness of each section of the rail is different, so it is necessary to calculate the value of the bending stiffness of the rail using a formula. Step 5: The testing equipment calculates the vertical vibration displacement of the rail using formulas based on the collected flexural displacement and bending stiffness data of the rail. Step Six: After obtaining the displacement change of the vertical vibration position of the rail through Steps One to Five, the testing equipment will automatically complete the detection and judgment of the rail based on the obtained data, thus completing the detection of the rail. When the rail breaks or is damaged, the moment of inertia I The vertical displacement will increase as the vertical displacement decreases. By comparing the flexural deformation of the rail under the same dynamic action with the normal value, the integrity of the rail can be preliminarily inferred. In step six, if the displacement change calculated by the testing equipment is less than 10% of the standard value, then no attention needs to be paid to that section of the rail. When the displacement change calculated by the testing equipment is 10% to 30% of the standard value, the testing equipment will retrieve the historical data of the rail section for comparison and mark it. When the displacement of the marked rail continues to increase and reaches or exceeds 30% of the standard value, the testing equipment will perform waveform analysis on the marked rail and then issue a warning of rail breakage.

2. A method of testing a rail for fracture according to claim 1, characterised in that: In step three, the formula is derived as: wherein u represents the deflection displacement of the rail, E represents the elastic modulus of the rail, I represents the moment of inertia of the rail, and represents the vertical vibration displacement of the rail.

3. A method of testing a rail for fracture according to claim 1, wherein: In step four, the formula is a bending stiffness formula. Based on the material of the rail, the bending stiffness of the rail is calculated. The bending stiffness represents the rail's resistance to bending deformation. Therefore, under the same external bending moment, when the bending stiffness is larger, the flexural deformation of the rail will be reduced, and its ability to resist bending deformation will be stronger.

4. The rail fracture testing method according to claim 3, characterized in that: The bending stiffness formula is: where k represents the bending stiffness of the rail, u represents the deflection displacement of the rail, E represents the elastic modulus of the rail, and represents the vertical inertia moment to which the rail is subjected.

5. The rail fracture testing method according to claim 1, characterized in that: In step five, the formula is a deflection deformation equation, the differential equation general solution of which is: And the steel rail is rigidly fixed or laid on the line, with a constraint condition, so that the calculation conforms to the actual use, and therefore the deflection deformation equation is: Wherein, represents the vertical vibration displacement of the steel rail, k represents the bending stiffness of the steel rail, and u represents the deflection displacement of the steel rail.

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