Rail fracture testing method

Abstract

The present invention provides a rail fracture testing method, comprising the following steps: step 1, by means of vibration sensors at ends of an axle box of a vehicle running part, collecting vibration displacement applied to rails by the vehicle running part; step 2, the vibration sensors converting the collected mechanical vibration displacement into electric signals, and transmitting the electric signals to a signal collector of a testing device; step 3, a signal processing unit calculating and deriving flexural deformation of the rails by means of the principle of mechanics and a formula; step 4, calculating the bending stiffness of the rails of the current section by means of a formula; step 5, on the basis of collected flexural displacement data and bending stiffness data of the rails, the testing device further calculating the vertical vibration displacement and the change rate of the rails by means of a formula; and step 6, on the basis of the obtained data, the testing device automatically completing detection, analysis and determination of the rails. Therefore, the problem that a user needs to manually operate for recognition during testing of a traditional flaw detection car is solved, and testing can be conducted without scheduling a dedicated maintenance window, thereby improving the testing efficiency.

Description

A rail fracture testing method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 5, 2023, with application number 202311649096.X and invention name “A Method for Testing Rail Fracture”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the technical field of track detection, and more specifically, relates to a rail fracture testing method. Background Art

[0003] With the development of railway transportation, rails have become an important component of railway transportation, providing a working surface for support, running and guidance for train wheels. Maintaining the integrity of rails is a necessary condition for ensuring the safe operation of trains. However, under the load of trains, rails will inevitably suffer various types of damage. Among them, rail breakage is the most serious damage that affects the safety of train operation and must be discovered and dealt with in a timely manner.

[0004] For example, the Chinese utility model patent with patent number 202321351872.3 provides a rail damage detection mechanism and a rail flaw detection vehicle. The rail flaw detection vehicle is set up by a traction vehicle and a detection vehicle. When in use, the detection vehicle is pulled by the power running gear of the traction vehicle, and the detection vehicle uses an electromagnetic probe mechanism and an ultrasonic wheel detection mechanism to perform ultrasonic and electromagnetic detection on the rails, thereby improving the accuracy of detection; however, traditional flaw detection trolley detection has certain limitations. It needs to be placed on the rails during the skylight period of the line and then detect it. It also requires manual operation by the user, and cannot achieve normal monitoring of the rails, which reduces the detection efficiency.

[0005] Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a rail fracture testing method to solve the technical problem in the prior art that traditional flaw detection vehicles require manual operation by users during testing, and are placed on the rails during the window period of the line, which makes it impossible to achieve normalized monitoring of the rails and reduces the detection efficiency.

[0007] The purpose and efficacy of the rail fracture testing method of the present invention are achieved by the following specific technical means:

[0008] A rail fracture testing method includes a rail and a train, the train including a running gear, the top of the rail in contact with the running gear, vibration sensors disposed at both ends of an axle box of the running gear, a carriage disposed on top of the running gear, a testing device disposed within the carriage, and two sets of vibration sensors electrically connected to the testing device.

[0009] The testing method comprises the following steps:

[0010] Step 1: When the train runs on the rails, the wheels of the running gear will apply load to the rails, causing vibration and displacement. A vibration sensor installed at the end of the axle box of the running gear will collect the vibration displacement applied by the running gear to the rails.

[0011] Step 2: The vibration sensor can convert the collected mechanical vibration displacement into an electrical signal. A data line or wireless connection is used between the vibration sensor and the test equipment. The test equipment includes a signal acquisition and analyzer. The vibration sensor transmits the electrical signal obtained by the displacement conversion to the signal acquisition instrument through a connecting line. The signal acquisition instrument collects, amplifies and encodes the electrical signals input from each channel, and then transmits them to the signal processing unit in the test equipment.

[0012] Step 3: The signal processing unit calculates and derives the deflection of the rail using a formula based on the mechanical principle that the rail will bend when subjected to a load;

[0013] 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;

[0014] Step 5: The testing equipment calculates the vertical vibration displacement of the rail using a formula based on the collected flexural displacement data and bending stiffness data of the rail;

[0015] Step 6: After obtaining the displacement change of the vertical vibration position of the rail through steps 1 to 5, the testing equipment will analyze the obtained data, automatically complete the detection and judgment of the rail, and complete the detection of the rail.

[0016] As a further solution of the present invention, in step three, the derivation formula is:

[0017] Wherein, u represents the flexural displacement of the rail, E represents the elastic modulus of the rail, I represents the moment of inertia of the rail, and y(x) represents the vertical vibration displacement of the rail.

[0018] As a further solution of the present invention, in step three, when the rail is broken or damaged, the moment of inertia I will decrease and the vertical displacement generated will increase. 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.

[0019] As a further solution of the present invention, in step four, the formula is a bending stiffness formula, which calculates the bending stiffness of the rail based on the material of the rail. The bending stiffness represents the resistance of the rail to bending deformation. Therefore, under the same external force and 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 also be stronger.

[0020] As a further solution of the present invention, the bending stiffness formula is:

[0021] Wherein, k represents the bending stiffness of the rail, u represents the flexural displacement of the rail, E represents the elastic modulus of the rail, and I x It represents the vertical moment of inertia of the rail.

[0022] As a further solution of the present invention, in step 5, the formula is a flexural deformation equation, and the general differential equation solution of the equation is:

[0023] y(x)=C1e kx coskx+C2e kx sinkx+C3e -kx coskx+C4e -kx sinkx;

[0024] The rails are rigidly fixed on the line and have constraints. In order to make the calculation consistent with actual usage, the deflection deformation equation is:

[0025] Wherein, y(x) represents the vertical vibration displacement of the rail, k represents the bending stiffness of the rail, and u represents the flexural displacement of the rail.

[0026] As a further solution of the present invention, in step six, when the displacement change calculated by the testing equipment is less than 10% of the standard value, the section of the rail does not need to be paid attention to.

[0027] As a further solution of the present invention, in step six, when the displacement change calculated by the testing device is 10% to 30% of the standard value, the testing device will retrieve historical data of the section of the rail for comparison and mark it.

[0028] As a further solution of the present invention, when the displacement change 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 rail breakage warning.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Compared with the existing technology, the test equipment is installed on a regular operating train through the setting of the test equipment, and the signal acquisition instrument and signal processing unit of the test equipment are used to automatically collect, record and analyze the data, which solves the problem that the traditional flaw detection vehicle inspection requires manual operation by the user. There is no need to arrange special window time for testing. The whole process does not require manual operation, saving labor costs, and realizing real-time monitoring, timely discovering problems and issuing alarms, thereby improving detection efficiency.

[0031] 2. Through the setting of vibration sensors and vehicle running gear, when using this test method, the vibration sensor can collect rail vibration displacement data, provide data input for subsequent calculations, and then use the formula to calculate the flexural displacement, bending stiffness and vertical vibration displacement of the rail; then the integrity of the rail is judged based on the displacement change. When the displacement change reaches a certain level, it is judged that the rail is damaged and needs attention and repair; this test method avoids the trouble of manual inspections, can monitor the condition of the rail in real time, and effectively improves safety.

[0032] 3. By setting the threshold, when using this test method, the rail parameters are calculated through theoretical calculation formulas and then compared with the standard values, which can more accurately determine the health of the rail. If the displacement change is within 10%, the rail is considered normal; if it is between 10% and 30%, it requires attention; if it exceeds 30%, the rail is considered damaged and needs repair. This quantitative judgment can minimize the probability of false alarms and improve the accuracy of the test results.

[0033] Figures in the specification

[0034] FIG1 is a calculation flow chart of a rail fracture testing method of the present invention;

[0035] FIG2 is a schematic diagram of an increase in vertical displacement of a rail caused by a crack in a rail fracture testing method according to the present invention;

[0036] FIG3 is a schematic diagram showing the changing trend of the vertical displacement y(x) and the moment of inertia I in a rail fracture testing method according to the present invention. DETAILED DESCRIPTION

[0037] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with the accompanying drawings and examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0038] Example:

[0039] The test method includes the following steps:

[0040] Step 1: When a train runs on rails, the wheels of the running gear vibrate and exert a displacement force on the rails. The wheels of the running gear are in direct contact with the rails, and the rails will bend when the wheels roll over them. To detect this deformation, vibration sensors are installed at both ends of the axle box of the running gear. The vibrations are transmitted to the vibration sensors through the running gear. The vibration sensors can detect the mechanical vibration and displacement exerted by the wheels on the rails in real time, avoiding the trouble of manual inspection of the rails and improving inspection efficiency and safety.

[0041] Step 2: The vibration sensor can detect the mechanical vibration displacement of the rail and convert it into a corresponding electrical signal. These electrical signals 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 encoding 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 collect the output signals of multiple vibration sensors at the same time. The signal acquisition instrument will first filter and amplify the input electrical signals to eliminate interference signals, and then encode the signals. The encoded digital signals are then sent to the signal processing unit in the test equipment, realizing the collection, transmission, processing, analysis and judgment of the mechanical vibration displacement signals of the rail.

[0042] Step 3: 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 wheels on the rail will cause the rail to bend and deform. The signal processing unit can calculate the theoretical flexural deformation (flexural displacement) of the rail under the action of this external force based on the input rail parameters, using mechanical principles and relevant formulas to ensure detection accuracy and reliability.

[0043] The calculation formula for the flexural displacement is:

[0044] Among them, u represents the flexural displacement of the rail, E represents the elastic modulus of the rail, I represents the moment of inertia of the rail, and y(x) represents the vertical vibration displacement of the rail. The test equipment uses the derived formula to calculate the theoretical flexural displacement of the rail, providing a basis for judging the structural integrity. Selecting the bending stiffness of the corresponding section can improve the calculation accuracy and make the results more accurately reflect the actual state of the rail.

[0045] As shown in Figure 3, when a rail is broken or damaged, its cross-sectional dimensions and moment of inertia (I) decrease. Under the same external force, this reduced cross-sectional dimension and moment of inertia (I) decrease the structural stiffness, resulting in increased flexural deformation and vibration displacement. When testing the rail, the testing equipment selects the same testing conditions and the same dynamic force, collects rail flexural displacement data, and then compares the collected data with theoretically calculated values ​​or historical data under normal conditions. If the collected data is significantly greater than the normal value, it indicates that under the same external force, the rail deformation has increased and the structural stiffness has decreased, likely due to a decrease in cross-sectional dimensions or moment of inertia (I). This indicates that the rail structure may be damaged or broken, requiring attention. If the difference between the collected data and the normal value is within the allowable range, the rail structure is intact. Under the same dynamic force, the structural deformation response does not change significantly, indicating that the cross-sectional dimensions and moment of inertia (I) have not decreased, and the structural stiffness has not decreased. This can be used to preliminarily determine that the rail structure is intact and no further attention is required. Therefore, the testing equipment uses a method of multiple tests on the rails under the same testing conditions and power, and compares the results with normal values, which can effectively determine the integrity of the rail structure and safeguard railway safety.

[0046] Step 4: The stiffness of the rail refers to the ability of the rail to resist deformation, which is related to the material properties and structural geometric dimensions of the rail. Due to the long length of the rail, local deformation is inevitable during the laying and use process, which makes the stiffness of each section of the rail different. If this difference is not taken into account and a unified theoretical calculation model is directly adopted, it is likely to cause errors in the detection results; therefore, in order to improve the detection accuracy, the signal processing unit needs to calculate the stiffness of the rails in different sections separately when calculating the theoretical flexural deformation, and obtain the bending stiffness value of the rails in each section. Then, the actual force is substituted into the calculation model of the corresponding section to obtain a more accurate theoretical flexural deformation. The rail is calculated through the formula, which further improves the accuracy of the calculation results.

[0047] Wherein, please refer to FIG2 . In step 4 thereof, the formula is the bending stiffness formula. Bending stiffness represents the rail's resistance to bending deformation. A larger value indicates a stronger resistance to bending deformation. Under the same external bending moment, the greater the bending stiffness, the smaller the flexural deformation of the rail will be, and the stronger its resistance to bending deformation will be. The testing equipment can calculate the theoretical bending stiffness of different sections based on the material and cross-sectional dimensions of the rail. If, under the same external bending moment, the flexural deformation of the rail is greater than the theoretical calculated value, it indicates that the bending stiffness of the section may have decreased and its resistance to deformation has weakened. It is possible that a crack has occurred on the rail, and the vertical displacement caused by the crack has a specific steady-state waveform shape. Therefore, the testing equipment can compare the steady-state waveform shape of the rail with the theoretical calculated value to determine whether the bending stiffness of different sections of the rail has changed. This method can avoid the error of a single test result and improve the accuracy of the judgment.

[0048] The bending stiffness formula is:

[0049] Wherein, k represents the bending stiffness of the rail. The greater the bending stiffness, the stronger the rail's ability to resist bending deformation; u represents the flexural displacement of the rail. Under the same external force, the greater the bending stiffness k, the smaller the flexural displacement u; E represents the elastic modulus of the rail. The greater the elastic modulus, the higher the stiffness of the material and the stronger its ability to resist deformation; I x It represents the vertical moment of inertia of the rail. The larger the moment of inertia, the stronger the cross-section's resistance to bending deformation. Therefore, according to the bending stiffness formula, the bending stiffness k of the rail is positively correlated with the elastic modulus E and the moment of inertia I. The larger the elastic modulus E and the moment of inertia I, the higher the bending stiffness k and the stronger the rail's ability to resist bending deformation.

[0050] Step 5: During the rail inspection process, the testing equipment not only collects the rail's flexural deformation data, but also obtains the bending stiffness values ​​of the rails in different sections. The testing equipment can calculate the vertical vibration displacement of the rail based on the input flexural displacement data and bending stiffness data using a formula. If the actual flexural deformation exceeds a certain range of the theoretical calculated value, it indicates that there is abnormal vibration displacement, which is likely caused by structural damage.

[0051] As shown in FIG3 , in step 5, the formula is the flexural deformation equation, and the general differential equation solution of the equation is:

[0052] y(x)=C1e kx coskx+C2e kx sinkx+C3e -kx coskx+C4e -kx sinkx.

[0053] However, the rails are rigidly fixed on the track and have constraints. To ensure that the calculations are consistent with actual usage, the test equipment uses the following flexural deformation equation:

[0054] Where y(x) represents the vertical vibration displacement of the rail, k represents the bending stiffness of the rail, and u represents the flexural displacement of the rail. According to this equation, the process from the initiation of a crack to the change in vertical displacement is a cubic exponential process. By analyzing the flexural deformation equation, we can determine the relationship between the crack growth ratio and the displacement change ratio. It can be concluded that in the early stages of a crack, the vertical displacement changes little. As the crack grows, the displacement change gradually increases, and the sensitivity increases.

[0055] Step 6: Through the above steps, the test equipment obtains the displacement changes of the vertical vibration position of different sections of the rail, and compares it with the threshold to determine whether the structure of the rail is intact, thus completing the inspection of the rail; the test equipment will also make a comprehensive judgment on the current set of test data and historical data to try to avoid the occurrence of false alarms. At the same time, it will also monitor the long-term status of the rail through big data analysis to improve the detection accuracy. This method can provide a strong guarantee for ensuring the safety of railway operations.

[0056] In step six, when the rail displacement change calculated by the test equipment is 10% of the standard value, it means that the flexural deformation of this section of rail is small and its ability to resist bending deformation is strong, so this section of rail does not need to be paid attention to; this also means that the bending stiffness of this section of rail is large and can withstand the same external force and bending moment, thereby reducing the flexural deformation it produces; in actual use, the test equipment will automatically judge the integrity of the rail based on the calculated displacement change, and perform corresponding processing and early warning to ensure the safety of train operation.

[0057] In step six, when the rail displacement change calculated by the test equipment is 10% to 30% of the standard value, the test equipment will take further measures to evaluate the condition of the rail. To more accurately determine the health status of the rail, the test equipment will retrieve the historical data of the section of rail for comparative analysis. By comparing with the historical data, the test equipment can detect whether there are potential problems or abnormal changes in the rail. At the same time, the test equipment will mark these rails with potential problems for subsequent monitoring and maintenance, and can also remind relevant personnel to observe and pay more close attention to these rails, and take necessary repair or replacement measures. Through timely marking and treatment, the risk of rail failure and breakage can be effectively prevented and reduced, ensuring the safety and reliability of railway transportation.

[0058] When the displacement change of a 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. This waveform analysis allows the testing equipment to further understand the rail's vibration characteristics and deformation patterns. Further analysis of the rail displacement waveform, as shown in Figure 2, can be performed to determine whether the rail has cracked based on the characteristics of the displacement waveform. Combining rail displacement change testing and waveform analysis allows for multi-faceted identification of rail cracks, enabling more accurate prediction of rail fracture. When a rail crack develops, an increase in vertical displacement y(x) indicates a decrease in the moment of inertia I, indicating a possible crack. Once the testing equipment confirms a risk of rail breakage through waveform analysis, it will immediately issue a breakage warning signal. This warning signal is then sent to relevant maintenance personnel or monitoring systems, allowing them to take immediate emergency measures, such as limiting train speeds or urgently repairing or replacing damaged rails, to ensure train safety.

[0059] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A rail fracture testing method, characterized in that: The following steps are included: Step 1: When the train is running on the rails, the wheels of the vehicle running gear will apply vibration and displacement to the rails. Vibration sensors are installed at both ends of the axle box of the vehicle running gear to collect the vibration displacement applied by the vehicle running gear to the rails; Step 2: The vibration sensor can convert the collected mechanical vibration displacement into an electrical signal. A test and analysis device is installed on the train, and the vibration sensor and the test device are connected by a data line or wirelessly. The test device includes a signal acquisition analyzer. The vibration sensor transmits the electrical signal obtained by the displacement conversion to the signal acquisition device through a connecting line. The signal acquisition device collects, amplifies and analyzes the electrical signals input from each channel, and then transmits them to the signal processing unit in the test device. Step 3: The signal processing unit calculates and derives the flexural deformation of the rail and its changing rules using a formula based on the mechanical principle that the rail will flex and deform when subjected to a load; Step 4: The stiffness of each section of the rail is different, so it is necessary to calculate by a formula to obtain the value of the bending stiffness of the rail; Step 5: The testing equipment can further calculate the vertical vibration displacement of the rail by calculating the collected flexural displacement data and bending stiffness data of the rail through a formula; Step 6: After obtaining the displacement change of the vertical vibration position of the rail through steps 1 to 5, the testing equipment will automatically complete the detection and judgment of the rail according to the obtained data, and complete the detection of the rail.

2. A rail fracture testing method according to claim 1, characterized in that: In step three, the derivation formula is: Wherein, u represents the flexural displacement of the rail, E represents the elastic modulus of the rail, I represents the moment of inertia of the rail, and y(x) represents the vertical vibration displacement of the rail.

3. A rail fracture testing method according to claim 2, characterized in that: When the rail is broken or damaged, the moment of inertia I will decrease and the vertical displacement will increase. By comparing the flexural deformation of the rail under the same dynamic force with the normal value, the integrity of the rail can be preliminarily inferred.

4. A rail fracture testing method according to claim 1, characterized in that: In step four, the formula is a bending stiffness formula, which calculates the bending stiffness of the rail based on the material of the rail. The bending stiffness represents the resistance of the rail to bending deformation. Therefore, under the same external force and 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 also be stronger.

5. A rail fracture testing method according to claim 4, characterized in that: The bending stiffness formula is: Where, k represents the bending stiffness of the rail, u represents the flexural displacement of the rail, E represents the elastic modulus of the rail, and I x It represents the vertical moment of inertia of the rail.

6. A rail fracture testing method according to claim 1, characterized in that: In step 5, the formula is the flexural deformation equation, and the differential equation of the equation is generally solved as follows: y(x)=C1e kx coskx+C2e kx sinkx+C3e -kx coskx+C4e -kx sinkx; The rails are rigidly fixed or laid on the line, and there are constraints to make the calculation In line with the actual use, the deflection deformation equation is: Among them, y(x) represents the vertical vibration displacement of the rail, k represents the bending stiffness of the rail, and u represents the flexural displacement of the rail.

7. A rail fracture testing method according to claim 1, characterized in that: In step six, when the displacement change calculated by the testing equipment is less than 10% of the standard value, the section of the rail does not need to be paid attention to.

8. A rail fracture testing method according to claim 1, characterized in that: 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 section of the rail for comparison and mark it.

9. A rail fracture testing method according to claim 8, characterized in that: When the displacement change 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 rail breakage warning.

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