Ultrasonic guided wave detection method and detection system for identifying steel rail crack

Abstract

The invention discloses an ultrasonic guided wave detection method and system for identifying steel rail cracks, and the method comprises the steps: collecting an ultrasonic reflection signal; reconstructing the ultrasonic reflection signal through a crack reflection wave dictionary, and determining a reconstructed ultrasonic signal; determining an ultrasonic reflection time based on the reconstructed ultrasonic signal and the ultrasonic reflection signal; and determining the crack position according to the ultrasonic reflection time. By reconstructing the collected ultrasonic guided wave data, the damage position on the steel rail can be positioned with high precision, and the detection reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of track detection, and in particular to an ultrasonic guided wave detection method and a detection system for identifying rail cracks. Background Art

[0002] Rails are important infrastructure in the railway system, and their safety and reliability are directly related to the safety of train operation and transportation efficiency. During long-term use, rails are prone to various types of damage due to the influence of train loads, environmental factors (such as temperature changes, corrosion), and material fatigue. Among them, cracks are the most common and most harmful. Therefore, timely and accurate detection of rail cracks is crucial. At present, with the development of ultrasonic technology, ultrasonic testing technology, as a non-destructive testing method, has the advantages of large detection depth, high sensitivity, and real-time imaging, and has gradually become the mainstream technology for rail crack detection.

[0003] However, due to the complex geometry of the rails and the anisotropy of the material, the propagation path of the ultrasonic wave is complicated. The existing detection method of collecting ultrasonic signals through sensors is not accurate enough to accurately determine the damage location on the rails. Multiple tests are required to improve the reliability of the test results, which affects the detection efficiency and makes the detection operation complicated.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide an ultrasonic guided wave detection method and detection system for identifying rail cracks, aiming to solve the problems of complex operation, low efficiency and insufficient reliability of existing rail detection.

[0006] The technical solution of the present invention is as follows: An ultrasonic guided wave detection method for identifying rail cracks, comprising: Collecting ultrasonic reflection signals; Reconstructing the ultrasonic reflection signal through the crack reflection wave dictionary to determine the reconstructed ultrasonic signal; determining an ultrasound reflection time based on the reconstructed ultrasound signal and the ultrasound reflection signal; The crack position is determined according to the ultrasonic reflection time.

[0007] In the ultrasonic guided wave detection method for identifying rail cracks, the step of collecting ultrasonic reflection signals specifically includes: An ultrasonic component is arranged on the surface of the rail; wherein the ultrasonic component comprises a first signal generator, a second signal generator, a first signal receiver and a second signal receiver, wherein the first signal generator and the second signal generator are arranged along the height direction of the rail; the first signal receiver and the second signal receiver are arranged along the height direction of the rail; the first signal generator and the first signal receiver are arranged along the length direction of the rail; the second signal generator and the second signal receiver are arranged along the length direction of the rail; The first signal generator is started to generate a first ultrasonic signal, and a first reflection signal reflected by the crack is collected through the first signal receiver; the second signal generator is started to generate a second ultrasonic signal, and a second reflection signal reflected by the crack is collected through the second signal receiver; The first reflection signal and the second reflection signal are recorded as ultrasonic reflection signals.

[0008] The ultrasonic guided wave detection method for identifying rail cracks, wherein the first signal generator is a piezoelectric ceramic sensor, and / or the second signal generator is a piezoelectric ceramic sensor; The first signal receiver is a fiber Bragg grating sensor, and / or the second signal receiver is a fiber Bragg grating sensor.

[0009] The ultrasonic guided wave detection method for identifying rail cracks, wherein the first ultrasonic signal is a sine wave modulated by a 5-cycle Hanning window, and the center frequency is 300 kHz; the second ultrasonic signal is a sine wave modulated by a 5-cycle Hanning window, and the center frequency is 300 kHz.

[0010] In the ultrasonic guided wave detection method for identifying rail cracks, the step of reconstructing the ultrasonic reflection signal by using the crack reflection wave dictionary and determining the reconstructed ultrasonic signal specifically comprises: Initialize residual and index set; Perform correlation matching between the ultrasonic reflection signal and dictionary elements in the crack reflection wave dictionary, select the dictionary element with the greatest correlation based on the condition of reducing residual error, and construct an index set in the current iteration number; Perform linear regression calculation on the index set in the current iteration to determine the weight matrix in the current iteration; Determine an approximate reconstructed signal in the current iteration number based on the weight matrix in the current iteration number; Determine a residual of a current iteration number based on the approximate reconstructed signal and the ultrasonic reflection signal; Verify whether the current number of iterations reaches the condition for iteration termination. When the result is no, bring the residual of the current number of iterations and the index set in the current number of iterations into the next iteration, and select a new index set from the index set of the current number of iterations based on the condition of reducing the residual until the iteration termination condition is reached, and output the reconstructed ultrasound signal; wherein, the condition for iteration termination is the preset number of iterations.

[0011] The ultrasonic guided wave detection method for identifying rail cracks, wherein the step of determining the crack position based on the ultrasonic reflection time specifically includes: Determine, based on the ultrasonic reflection time, a propagation distance of the first ultrasonic signal reflected by the crack and propagated to the first signal receiver, and a propagation distance of the second ultrasonic signal reflected by the crack and propagated to the second signal receiver; Establishing a rectangular coordinate system, taking the midpoint of the line connecting the first signal receiver and the second signal receiver as the origin, taking the direction of the line connecting the first signal receiver and the second signal receiver as the y direction, and determining the coordinates of the first signal generator, the second signal generator, the first signal receiver, and the second signal receiver; The coordinates of the crack are determined based on the coordinates of the first signal generator, the coordinates of the second signal generator, the coordinates of the first signal receiver, the coordinates of the second signal receiver, the propagation distance of the first ultrasonic signal reflected from the crack and propagated to the first signal receiver, and the propagation distance of the second ultrasonic signal reflected from the crack and propagated to the second signal receiver.

[0012] The ultrasonic guided wave detection method for identifying rail cracks, wherein the vertical coordinate of the crack is , satisfying the following relationship: ; The horizontal coordinate of the crack is , satisfying the following relationship: ; Among them, the is the propagation distance of the first ultrasonic signal reflected by the crack and propagated to the first signal receiver; is the propagation distance of the second ultrasonic signal reflected by the crack and propagated to the second signal receiver; It is half of the connection distance between the first signal receiver and the second signal receiver.

[0013] In the ultrasonic guided wave detection method for identifying rail cracks, the method for constructing the crack reflection wave dictionary includes: Determine a first waveform feature based on the waveform and frequency of the ultrasonic wave propagating on the rail; Processing the first waveform feature based on a plurality of preset hysteresis times and a plurality of amplitude decay rates to determine a plurality of second waveform features; Superimposing each of the second waveform features with the first waveform feature to determine reference waveform features of multiple crack reflection waves; All of the reference waveform features are collected to construct a crack reflection wave dictionary that characterizes the waveform features of different crack reflection waves.

[0014] The ultrasonic guided wave detection method for identifying rail cracks, wherein the lag time is 10-15 microseconds; and the amplitude attenuation rate is 0-0.9.

[0015] The present application also discloses an ultrasonic guided wave detection system for identifying rail cracks, which comprises: An ultrasonic excitation module is arranged on the rail and is used to generate ultrasonic signals; An ultrasonic receiving module is provided on the rail and is used to collect ultrasonic reflection signals; A central control module is connected to the ultrasonic excitation module and the ultrasonic receiving module. The central control module is used to carry a preset crack reflection wave dictionary, reconstruct the ultrasonic reflection signal through the crack reflection wave dictionary, determine the ultrasonic reflection time, and determine the crack position based on the ultrasonic reflection time.

[0016] Compared with the prior art, the embodiments of the present invention have the following advantages: The ultrasonic guided wave detection method for identifying rail cracks disclosed in the present invention reconstructs the ultrasonic reflection signal collected on the rail, uses the crack reflection wave dictionary to find the waveform characteristics formed by the ultrasonic guided wave after the crack reflection, and then tracks the position of the reflection wave in the detection result of the ultrasonic reflection signal to determine the propagation time of the ultrasonic guided wave. The propagation speed of the ultrasonic guided wave can be known from existing data and is certain, so when the propagation time of the ultrasonic guided wave from the beginning of propagation to the collection is obtained, the length of the propagation path can be determined, so the information obtained based on the ultrasonic reflection signal processing can reversely infer the crack position, thereby achieving fast, high-precision, and high-reliability detection of the crack position, reducing the difficulty of operation and improving the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a flow chart of the ultrasonic guided wave detection method for identifying rail cracks in the present invention; Figure 2 It is a schematic diagram of the assembly of the ultrasonic guided wave detection system for identifying rail cracks in the present invention; Figure 3 is a waveform diagram of the first ultrasonic signal or the second ultrasonic signal in the present invention; Figure 4 is another waveform diagram of the first ultrasonic signal or the second ultrasonic signal in the present invention; Figure 5 It is a schematic diagram of the positions of the first signal generator, the second signal generator, the first signal receiver, the second signal receiver and the cracks on the rail surface in the present invention; Figure 6 It is a schematic diagram of the structure of the crack reflection wave dictionary in the present invention; Figure 7 A diagram showing a step of determining a reconstructed ultrasound signal in one embodiment of the present invention; Figure 8 This is a diagram showing the effect of matching tracking and identification of ultrasonic reflection signals and reconstructed ultrasonic signals in the present invention; Fig. 9 It is a schematic diagram of the positions of the first signal generator, the second signal generator, the first signal receiver, the second signal receiver and the crack in the rectangular coordinate system in the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, in one embodiment of the present invention application, an ultrasonic guided wave detection method for identifying rail cracks is disclosed, which includes: S10, collecting ultrasonic reflection signals.

[0021] In this embodiment, the rails are detected by ultrasound. Specifically, a sensor is set on the side of the rails so that the ultrasound on the surface of the rails can be collected. The hysteresis characteristics and attenuation characteristics of the normally propagating ultrasound and the ultrasound reflected by the crack position are used to locate the crack position.

[0022] Specifically, as an implementation of this embodiment, step S10 is disclosed to specifically include: S11, setting an ultrasonic component on the surface of the rail; wherein, Figure 1 and Figure 5 As shown, the ultrasonic component includes a first signal generator, a second signal generator, a first signal receiver and a second signal receiver, the first signal generator and the second signal generator are arranged along the height direction of the rail; the first signal receiver and the second signal receiver are arranged along the height direction of the rail; the first signal generator and the first signal receiver are arranged along the length direction of the rail; the second signal generator and the second signal receiver are arranged along the length direction of the rail.

[0023] The signal generator and the signal receiver are arranged on the side of the rail, which occupies a small space and is hidden on the side of the rail, so it is not easy to fall, so the service life of the ultrasonic component can be extended. In this embodiment, two signal generators and two signal receivers are arranged to increase the positioning accuracy, and the signals generated by the superposition of two ultrasonic waves are used to accurately locate the position of the crack on the surface of the rail, thereby improving the positioning accuracy.

[0024] Specifically, the ultrasonic component can be fixed by welding or bonding, the assembly operation is simple, and it will not damage the rails.

[0025] like Figure 5 As shown, as another implementation of this embodiment, it is disclosed that the first signal generator is a piezoelectric ceramic sensor (PZT1); or, the second signal generator is a piezoelectric ceramic sensor (PZT2); or both the first signal generator and the second signal generator are piezoelectric ceramic sensors. The piezoelectric ceramic sensor utilizes the piezoelectric effect. When an alternating voltage is applied to both ends of the piezoelectric ceramic, the ceramic sheet will generate mechanical vibration due to the piezoelectric effect. This vibration is transmitted in the form of ultrasonic waves, thereby realizing the conversion of electrical energy into mechanical energy and generating ultrasonic guided waves on the surface of the rail. The first signal generator and the second signal generator adopt the same type and size structure, which can simplify the structure of the ultrasonic component, reduce the manufacturing and use costs, and facilitate control.

[0026] like Figure 2 As shown, in this embodiment, the first signal generator and the second signal generator can be connected to a power amplifier and an arbitrary waveform generator, and the power amplifier can control the frequency of the ultrasonic wave. Figure 3 and Figure 4 As shown, the arbitrary waveform generator can adjust the waveform to a time domain waveform (such as Figure 3 waveform shown) or frequency domain waveform (such as Figure 4 Therefore, by improving the control of the waveform and frequency of the ultrasonic wave, it is convenient to adjust the characteristics of the detection wave according to actual needs, collect accurate detection data, and increase the detection accuracy.

[0027] For example Figure 5 As shown, as another implementation of this embodiment, the first signal receiver is a fiber grating sensor (FBG1); or, the second signal receiver is a fiber grating sensor (FBG2); or, the first signal receiver and the second signal receiver are both fiber grating sensors. The use of fiber grating sensors to detect ultrasonic signals has the characteristics of small size, corrosion resistance, and not susceptible to electromagnetic interference, so it is conducive to improving the reliability of the detection results, thereby improving the effectiveness of the data processing results, and quickly and efficiently locating the damaged position on the rail.

[0028] For example Figure 2 As shown, the first signal receiver and the second signal receiver disclosed in this embodiment can be connected to a 3-port optical circulator, and the other two ports of the 3-port optical circulator are connected to a single laser source and a balanced photodetector, and the balanced photodetector is electrically connected to an oscilloscope, so that during the working process, the ultrasonic signal collected by the signal receiver is converted into an optical signal, and then the optical signal is converted into an electrical signal. The waveform can be displayed and recorded on the oscilloscope, which is convenient for processing and observation.

[0029] It should be noted that the types of the first signal generator, the second signal generator, the first signal receiver, and the second signal receiver disclosed in this embodiment are examples and not exhaustive, and the protection scope of the present invention is not limited to this. As long as other types of first signal generators, second signal generators, first signal receivers, and second signal receivers can achieve the technical effects disclosed in this application, they should also be within the scope of protection of this application as equivalent replacements for the concepts of the present invention.

[0030] Specifically, as another implementation of this embodiment, it is disclosed that the first ultrasonic signal is a sine wave modulated by a 5-cycle Hanning window, and the center frequency is 300 kHz; the second ultrasonic signal is a sine wave modulated by a 5-cycle Hanning window, and the center frequency is 300 kHz. The ultrasonic reflection signal disclosed in this embodiment includes two ultrasonic signals. When the crack position is inferred based on the ultrasonic reflection signal, the superposition calculation of the ultrasonic signals is involved. Therefore, the first ultrasonic signal and the second ultrasonic signal are set to sine waves with the same amplitude and frequency, so that the superimposed waveform generated when excited at the same time is more regular and easy to analyze, which is conducive to reducing the difficulty of ultrasonic tracking and improving detection efficiency and reliability.

[0031] S12, start the first signal generator to generate a first ultrasonic signal, and collect a first reflection signal reflected from the crack through the first signal receiver; start the second signal generator to generate a second ultrasonic signal, and collect a second reflection signal reflected from the crack through the second signal receiver.

[0032] The first ultrasonic signal and the second ultrasonic signal disclosed in this embodiment can occur successively, so that the first signal generator only collects the first ultrasonic signal that is directly transmitted or transmitted after reflection, and is not interfered by the second ultrasonic signal, thereby reducing the difficulty of analyzing the first reflected signal. Similarly, in this embodiment, when the second ultrasonic signal occurs, the second signal receiver only collects the second ultrasonic signal that is directly transmitted or the second reflected signal.

[0033] S13. Record the first reflection signal and the second reflection signal as ultrasonic reflection signals.

[0034] In this embodiment, two detection points are set to respectively perform two times of excitation and detection of ultrasonic signals, and two points are used to locate one point (ie, the crack position), thereby improving the detection accuracy of the crack position.

[0035] S20. Reconstruct the ultrasonic reflection signal through a crack reflection wave dictionary to determine a reconstructed ultrasonic signal.

[0036] Due to the complex shape of the rail, ultrasonic waves are prone to multiple reflections in the medium, so the collected ultrasonic reflection signals are messy. In this embodiment, the ultrasonic reflection signals are reconstructed through the crack reflection wave dictionary to obtain valid data for inferring the crack position.

[0037] like Figure 6 As shown, as another implementation of this embodiment, a method for constructing the crack reflection wave dictionary is disclosed, including: M10. Determine a first waveform feature based on the waveform and frequency of the ultrasonic wave propagating on the rail; M20. Processing the first waveform feature based on a plurality of preset hysteresis times and a plurality of amplitude attenuation rates to determine a plurality of second waveform features; M30, superimposing each of the second waveform features with the first waveform feature to determine reference waveform features of multiple crack reflection waves; M40. Collect all the reference waveform features to construct a crack reflection wave dictionary that characterizes the waveform features of different crack reflection waves.

[0038] When damage occurs on the rail disclosed in this embodiment, it is generally a small crack in the early stage. When the ultrasonic wave propagates to the crack position, it will be reflected at the two edges of the crack respectively, and the reflected waves generated by these two reflections will have time lag and amplitude attenuation. Based on this, in this embodiment, ultrasonic waves with different lag times and different amplitude attenuations are pre-superimposed with the original waveform to construct a crack reflection wave dictionary that characterizes different waveform characteristics and characterizes the redundancy of the waveform characteristics of the crack reflection wave. During the detection process, the crack reflection wave dictionary can be used to screen out the waveform with the greatest correlation with the detection scene, thereby determining the position of the first reflection signal or the second reflection signal in the ultrasonic reflection signal, and then inferring the crack position.

[0039] In summary, in this embodiment, a crack reflection plate dictionary is constructed by presetting a reasonable subsequent time and amplitude attenuation rate, so as to obtain the waveform information of the crack reflection on the rail in combination with the ultrasonic reflection signal.

[0040] Specifically, as another implementation of this embodiment, it is disclosed that the lag time is 10-15 microseconds (μs); and the amplitude attenuation rate is 0-0.9.

[0041] Specifically, as another implementation of this embodiment, step S20 is disclosed to specifically include: S21. Initialize the residual and index set.

[0042] Using the orthogonal matching pursuit algorithm, first initialize the residual, index set and other parameters. The details are as follows: ; ; ; in, is the initial residual; is an ultrasonic reflection signal, which may specifically be a first reflection signal or a second reflection signal; is the initial index set (since iteration has not started, the index set is an empty set); is the number of iterations.

[0043] S22, performing correlation matching between the ultrasonic reflection signal and dictionary elements in the crack reflection wave dictionary, selecting the dictionary element with the greatest correlation based on the condition of reducing residual error, and constructing an index set in the current iteration number.

[0044] In the At the beginning of the iteration, select the element (Its index is ) reconstructs the signal so that the residual Reduce, that is: = . Then the index of the dictionary element selected in this iteration is Update to index set ,Right now: .

[0045] It should be noted that, in the reconstruction process of the above formula, the selected dictionary elements do not appear in the previous iteration rounds.

[0046] S23. Perform linear regression calculation on the index set in the current iteration number to determine the weight matrix in the current iteration number.

[0047] After obtaining the index set of this iteration, linear regression is performed to calculate the weight matrix, namely: ;in, Dictionary of crack reflection waves.

[0048] S24. Determine an approximate reconstructed signal in the current iteration number based on the weight matrix in the current iteration number.

[0049] The first All selected dictionary elements in the iteration and the previous round are used to linearly reconstruct the target signal. The approximate reconstructed signal is as follows: .

[0050] S25, determining the residual of the current iteration number based on the approximate reconstructed signal and the ultrasonic reflection signal, as shown below: .

[0051] S26. Verify whether the current number of iterations reaches the condition for iteration termination. When the result is no, bring the residual of the current number of iterations and the index set in the current number of iterations into the next iteration, and select a new index set from the index set of the current number of iterations based on the condition of reducing the residual until the iteration termination condition is reached, and output the reconstructed ultrasound signal; wherein, the condition for iteration termination is a preset number of iterations.

[0052] In this embodiment, the residual is gradually reduced by incremental iteration, and the most relevant waveform feature is screened out from the crack reflection wave dictionary, thereby determining the waveform feature of the reflection wave of the crack.

[0053] like Figure 7 As shown, in one implementation of this embodiment, the process of determining the reconstructed ultrasound signal is as follows: Step 1: Initialize the residual and index set ; Step 2: Start incremental iteration; Step 3: Update the difference dictionary ; Step 4: Select the dictionary element index with the greatest relevance ; Step 5: Update the residual based on the dictionary element index and index set ; Step 6: Verify the stop iteration condition. If the result is no, return to step 3 for the next iteration process; if the result is yes, proceed to step 7; Step 7: Output coefficients to reconstruct the signal .

[0054] S30: Determine an ultrasound reflection time based on the reconstructed ultrasound signal and the ultrasound reflection signal.

[0055] like Figure 8 As shown, in this embodiment, the ultrasonic reflection signal includes all the reflected wave information collected by the first signal receiver or the second signal receiver, and the reconstructed ultrasonic signal is compared with the ultrasonic reflection signal to find the overlapping waveforms of the two, and determine the starting time of the waveform at the overlapping position ( Figure 8 The time from the start of ultrasonic signal propagation to the time of acquisition can be inferred from the t moment in the image, which is the ultrasonic reflection time.

[0056] S40, determining the crack position according to the ultrasonic reflection time.

[0057] After obtaining the ultrasonic reflection time, the propagation path of the ultrasonic wave can be calculated based on the propagation speed of the ultrasonic wave, and then the crack position can be inferred.

[0058] It can be seen that the ultrasonic guided wave detection method for rail cracks disclosed in this embodiment has fewer steps, high detection efficiency, and accurate inverse results, which is conducive to obtaining high-precision and high-reliability detection results.

[0059] Specifically, as another implementation of this embodiment, step S40 is disclosed to specifically include: S41, determining, based on the ultrasonic reflection time, a propagation distance of the first ultrasonic signal reflected by the crack and propagated to the first signal receiver, and a propagation distance of the second ultrasonic signal reflected by the crack and propagated to the second signal receiver; S42, establishing a rectangular coordinate system, taking the midpoint of the line connecting the first signal receiver and the second signal receiver as the origin, taking the direction of the line connecting the first signal receiver and the second signal receiver as the y direction, and determining the coordinates of the first signal generator, the second signal generator, the first signal receiver, and the second signal receiver; S43. Determine the coordinates of the crack based on the coordinates of the first signal generator, the coordinates of the second signal generator, the coordinates of the first signal receiver, the coordinates of the second signal receiver, the propagation distance of the first ultrasonic signal reflected from the crack and propagated to the first signal receiver, and the propagation distance of the second ultrasonic signal reflected from the crack and propagated to the second signal receiver.

[0060] The ultrasonic component disclosed in this embodiment is arranged on the side of the rail. When a crack occurs on the side wall of the rail, it is located on the same surface as the ultrasonic component, so a plane rectangular coordinate system can be established for calculation. In addition, since the first signal generator, the second signal generator, the first signal receiver and the second signal receiver are all relatively small in volume, the size of the initial crack is also relatively small, so these positions can be regarded as points and expressed by point coordinates in the rectangular coordinate system.

[0061] like Fig. 9 As shown, the distance between the first signal generator and the first signal receiver is set to , the distance between the first signal generator and the second signal generator is The first signal receiver and the second signal receiver are on the y-axis, so their coordinates are (0, ) and (0, - ); The coordinates of the first signal generator are (- , ), the coordinates of the second signal generator are (- ,- Then, according to the Euclidean distance calculation formula, the crack (i.e. Figure 8 The coordinates of the “damage” position in the , ), satisfying the following relationship: ; ; ; .

[0062] in, is the distance between the first signal generator and the crack; is the distance between the first signal receiver and the crack; is the distance between the second signal generator and the crack; is the distance between the second signal receiver and the crack; is the propagation distance of the first ultrasonic signal reflected by the crack and propagated to the first signal receiver; is the propagation distance of the second ultrasonic signal after being reflected by the crack and propagating to the second signal receiver.

[0063] In the actual detection process, it is reasonable to assume that the propagation distance of the crack reflection wave is much greater than the propagation distance of the ultrasonic wave that directly reaches the signal receiver, that is, and , so it can be simplified to: ; .

[0064] It can be seen that in this embodiment, based on the reverse calculation of the ultrasonic reflection signal, the position of the crack can be accurately obtained and the coordinates of the crack in the rectangular coordinate system can be located.

[0065] As another embodiment of the present application, an ultrasonic guided wave detection system for identifying rail cracks is disclosed, which includes an ultrasonic excitation module, an ultrasonic receiving module and a central control module. The ultrasonic excitation module is arranged on the rail and is used to generate an ultrasonic signal; the ultrasonic receiving module is arranged on the rail and is used to collect an ultrasonic reflection signal; the central control module is connected to the ultrasonic excitation module and the ultrasonic receiving module, and the central control module is used to carry a preset crack reflection wave dictionary, reconstruct the ultrasonic reflection signal through the crack reflection wave dictionary, determine the ultrasonic reflection time, and determine the crack position based on the ultrasonic reflection time.

[0066] In summary, the present application discloses an ultrasonic guided wave detection method for identifying rail cracks, which includes: S10, collecting ultrasonic reflection signals; S20, reconstructing the ultrasonic reflection signals through crack reflection wave dictionaries, and determining reconstructed ultrasonic signals; S30, determining ultrasonic reflection time based on the reconstructed ultrasonic signals and the ultrasonic reflection signals; S40, determining crack positions according to the ultrasonic reflection time. The ultrasonic reflection signals collected on the rails are reconstructed, and the waveform features formed by the ultrasonic guided waves reflected from the cracks are found using the crack reflection wave dictionary, and then the positions of the reflected waves are tracked in the detection results of the ultrasonic reflection signals, the propagation time of the ultrasonic guided waves is determined, and the crack positions are inferred, so as to achieve fast, high-precision, and high-reliability detection of crack positions, reduce the difficulty of operation, and improve detection efficiency.

[0067] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0068] It should be noted that the present invention takes the ultrasonic guided wave detection method and detection system for identifying rail cracks as an example to introduce the specific structure and working principle of the present invention, but the application of the present invention is not limited to the ultrasonic guided wave detection method and detection system for identifying rail cracks, and can also be applied to the production and use of other similar workpieces.

[0069] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An ultrasonic guided wave detection method for identifying rail cracks, characterized in that: include: Collecting ultrasonic reflection signals; Reconstructing the ultrasonic reflection signal through the crack reflection wave dictionary to determine the reconstructed ultrasonic signal; determining an ultrasound reflection time based on the reconstructed ultrasound signal and the ultrasound reflection signal; The crack position is determined according to the ultrasonic reflection time.

2. The ultrasonic guided wave detection method for identifying rail cracks according to claim 1, characterized in that: The step of collecting ultrasonic reflection signals specifically includes: An ultrasonic component is arranged on the surface of the rail; wherein the ultrasonic component comprises a first signal generator, a second signal generator, a first signal receiver and a second signal receiver, wherein the first signal generator and the second signal generator are arranged along the height direction of the rail; the first signal receiver and the second signal receiver are arranged along the height direction of the rail; the first signal generator and the first signal receiver are arranged along the length direction of the rail; the second signal generator and the second signal receiver are arranged along the length direction of the rail; The first signal generator is started to generate a first ultrasonic signal, and a first reflection signal reflected by the crack is collected through the first signal receiver; the second signal generator is started to generate a second ultrasonic signal, and a second reflection signal reflected by the crack is collected through the second signal receiver; The first reflection signal and the second reflection signal are recorded as ultrasonic reflection signals.

3. The ultrasonic guided wave detection method for identifying rail cracks according to claim 2, characterized in that: The first signal generator is a piezoelectric ceramic sensor, and / or the second signal generator is a piezoelectric ceramic sensor; The first signal receiver is a fiber Bragg grating sensor, and / or the second signal receiver is a fiber Bragg grating sensor.

4. The ultrasonic guided wave detection method for identifying rail cracks according to claim 2, characterized in that: The first ultrasonic signal is a sine wave modulated by a 5-cycle Hanning window, and the center frequency is 300 kHz; the second ultrasonic signal is a sine wave modulated by a 5-cycle Hanning window, and the center frequency is 300 kHz.

5. The ultrasonic guided wave detection method for identifying rail cracks according to any one of claims 2 to 4, characterized in that: The step of reconstructing the ultrasonic reflection signal by using the crack reflection wave dictionary and determining the reconstructed ultrasonic signal specifically comprises: Initialize residual and index set; Perform correlation matching between the ultrasonic reflection signal and dictionary elements in the crack reflection wave dictionary, select the dictionary element with the greatest correlation based on the condition of reducing residual error, and construct an index set in the current iteration number; Perform linear regression calculation on the index set in the current iteration to determine the weight matrix in the current iteration; Determine an approximate reconstructed signal in the current iteration number based on the weight matrix in the current iteration number; Determine a residual of a current iteration number based on the approximate reconstructed signal and the ultrasonic reflection signal; Verify whether the current number of iterations reaches the condition for iteration termination. When the result is no, bring the residual of the current number of iterations and the index set in the current number of iterations into the next iteration, and select a new index set from the index set of the current number of iterations based on the condition of reducing the residual until the iteration termination condition is reached, and output the reconstructed ultrasound signal; wherein, the condition for iteration termination is the preset number of iterations.

6. The ultrasonic guided wave detection method for identifying rail cracks according to claim 5, characterized in that: The step of determining the crack position according to the ultrasonic reflection time specifically includes: Determine, based on the ultrasonic reflection time, a propagation distance of the first ultrasonic signal reflected by the crack and propagated to the first signal receiver, and a propagation distance of the second ultrasonic signal reflected by the crack and propagated to the second signal receiver; Establishing a rectangular coordinate system, taking the midpoint of the line connecting the first signal receiver and the second signal receiver as the origin, taking the direction of the line connecting the first signal receiver and the second signal receiver as the y direction, and determining the coordinates of the first signal generator, the second signal generator, the first signal receiver, and the second signal receiver; The coordinates of the crack are determined based on the coordinates of the first signal generator, the coordinates of the second signal generator, the coordinates of the first signal receiver, the coordinates of the second signal receiver, the propagation distance of the first ultrasonic signal reflected from the crack and propagated to the first signal receiver, and the propagation distance of the second ultrasonic signal reflected from the crack and propagated to the second signal receiver.

7. The ultrasonic guided wave detection method for identifying rail cracks according to claim 6, characterized in that: The ordinate of the crack is , satisfying the following relationship: ； The horizontal coordinate of the crack is , satisfying the following relationship: ； Among them, the is the propagation distance of the first ultrasonic signal reflected by the crack and propagated to the first signal receiver; is the propagation distance of the second ultrasonic signal reflected by the crack and propagated to the second signal receiver; It is half of the connection distance between the first signal receiver and the second signal receiver.

8. The ultrasonic guided wave detection method for identifying rail cracks according to claim 1, characterized in that: The method for constructing the crack reflection wave dictionary includes: Determine a first waveform feature based on the waveform and frequency of the ultrasonic wave propagating on the rail; Processing the first waveform feature based on a plurality of preset hysteresis times and a plurality of amplitude decay rates to determine a plurality of second waveform features; Superimposing each of the second waveform features with the first waveform feature to determine reference waveform features of multiple crack reflection waves; All of the reference waveform features are collected to construct a crack reflection wave dictionary that characterizes the waveform features of different crack reflection waves.

9. The ultrasonic guided wave detection method for identifying rail cracks according to claim 8, characterized in that: The lag time is 10-15 microseconds; the amplitude attenuation rate is 0-0.

9.

10. An ultrasonic guided wave detection system for identifying rail cracks, characterized in that: include: An ultrasonic excitation module is arranged on the rail and is used to generate ultrasonic signals; An ultrasonic receiving module is provided on the rail and is used to collect ultrasonic reflection signals; A central control module is connected to the ultrasonic excitation module and the ultrasonic receiving module. The central control module is used to carry a preset crack reflection wave dictionary, reconstruct the ultrasonic reflection signal through the crack reflection wave dictionary, determine the ultrasonic reflection time, and determine the crack position based on the ultrasonic reflection time.

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