Turnout switch rail crack detection method and device based on nonlinear ultrasonic guided waves

Abstract

The invention provides a turnout switch rail crack detection method and device based on nonlinear ultrasonic guided waves, and the method comprises the steps: firstly, generating a first target fundamental wave signal containing a first fundamental wave signal and a second fundamental wave signal, the two sine wave signals are continuously and simultaneously sent, and the sending duration is longer than the transmission delay of the fundamental wave signal between the two end points of the turnout switch rail; then, a signal generated by vibration of the turnout switch rail is received, a first relative nonlinear coefficient of the signal is calculated, and whether cracks exist in the switch rail or not is judged by comparing the first relative nonlinear coefficient with a preset damage threshold value; if the crack is detected, a second target fundamental wave signal is sent, the signal is composed of a third fundamental wave signal and a fourth fundamental wave signal, detailed detection of a specific detection area is achieved by adjusting the positions of the two signals in a mixed area of the switch rail, and then the specific position of the crack in the switch rail is determined based on a second relative nonlinear coefficient. According to the invention, long-distance flaw detection of turnout switch rail cracks can be realized, and identification and positioning of the cracks are realized.

Description

Technical Field

[0001] The present application relates to the field of railway detection, and in particular to a method and device for detecting cracks in a turnout point rail based on nonlinear ultrasonic guided waves. Background Art

[0002] Turnout point rails are essential track equipment for the intersection of railway lines and for realizing high-speed trains turning or crossing lines. Due to their complex structure, changeable state and numerous diseases, they are the weak link of high-speed railway lines, the focus and difficulty of maintenance and repair, and are also key infrastructure that affects the stability and safety of driving. According to the survey of turnout point rail lines, crack damage is very common in turnout point rails, accounting for about 80% of the total damage of turnouts, and has become one of the main reasons for reducing their service life.

[0003] Traditional non-destructive testing methods for rails mainly include: magnetic particle testing, eddy current testing, magnetic flux leakage testing, machine vision testing, ultrasonic body wave testing and ultrasonic guided wave testing. Magnetic particle testing, magnetic flux leakage testing, eddy current testing and machine vision testing can only detect cracks on the surface or near the surface of the rail, but cannot detect internal cracks; rail flaw detection based on ultrasonic body waves cannot detect the entire cross-section of the rail and at a long distance. Placing the probe at a certain position on the point rail cannot cover the entire point rail; since the point rail is a variable-section component, the ultrasonic guided wave has a dispersion characteristic, and the guided wave mode changes during the propagation process, and the mode becomes extremely complex, resulting in the inability of the propagation linear ultrasonic guided wave detection method to distinguish between normal signals and defect signals. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a method and device for detecting cracks in a switch point rail based on nonlinear ultrasonic guided waves, which can realize long-distance flaw detection of cracks in a switch point rail based on a nonlinear ultrasonic guided wave method, and realize crack identification and positioning.

[0005] The technical solution of the embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a method for detecting cracks in a turnout point rail based on nonlinear ultrasonic guided waves, the method comprising:

[0007] Generate a first target fundamental wave signal acting on the switch point rail, wherein the first target fundamental wave signal includes a first fundamental wave signal and a second fundamental wave signal, the first fundamental wave signal and the second fundamental wave signal are continuously transmitted sine waves, the first fundamental wave signal and the second fundamental wave signal are transmitted simultaneously, and the transmission time length is greater than the transmission delay of the fundamental wave signal between the two end points of the switch point rail;

[0008] receiving a vibration signal generated in the switch point rail;

[0009] A first relative nonlinear coefficient is calculated for the vibration signal, and whether the switch point rail has a crack is determined based on a preset damage threshold; if the switch point rail has a crack, a second target fundamental wave signal acting on the switch point rail is generated, and a detection area in the switch point rail is detected by the second target fundamental wave signal, and the position of the crack in the switch point rail is determined based on the second relative nonlinear coefficient of the detection area, wherein the second target fundamental wave signal includes a third fundamental wave signal and a fourth fundamental wave signal, and the detection area is determined by changing the position of a mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the switch point rail.

[0010] In a second aspect, an embodiment of the present application further provides a turnout point rail crack detection device based on nonlinear ultrasonic guided waves, the device comprising:

[0011] A signal excitation device, used for generating a first target fundamental wave signal acting on the switch point rail, wherein the first target fundamental wave signal includes a first fundamental wave signal and a second fundamental wave signal, the first fundamental wave signal and the second fundamental wave signal are continuously transmitted sine waves, the first fundamental wave signal and the second fundamental wave signal are transmitted simultaneously, and the transmission time length is greater than the transmission delay of the fundamental wave signal between the two end points of the switch point rail; and when there is a crack in the switch point rail, generating a second target fundamental wave signal acting on the switch point rail, wherein the second target fundamental wave signal includes a third fundamental wave signal and a fourth fundamental wave signal;

[0012] A signal receiving device, used for receiving a vibration signal generated in the switch point rail;

[0013] A signal processing device, used for calculating a first relative nonlinear coefficient for the vibration signal, and determining whether there is a crack in the switch point rail based on a preset damage threshold; and when there is a crack in the switch point rail, detecting a detection area in the switch point rail by using the second target fundamental wave signal, and determining the position of the crack in the switch point rail based on the second relative nonlinear coefficient of the detection area, wherein the detection area is determined by changing the position of a mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the switch point rail.

[0014] In a third aspect, an embodiment of the present application further provides an electronic device, comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the storage medium through the bus, and the processor executes the machine-readable instructions to execute the turnout point rail crack detection method based on nonlinear ultrasonic guided waves as described in any one of the first aspects.

[0015] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method for detecting cracks in a turnout point rail based on nonlinear ultrasonic guided waves as described in any one of the first aspects is executed.

[0016] The embodiments of the present application have the following beneficial effects:

[0017] (1) Efficient and fast scanning: By using the signal excitation device to continuously emit sinusoidal signals and combining it with the nonlinear ultrasonic guided wave mixing method, the turnout point rail can be comprehensively and quickly scanned in a short period of time. This method greatly shortens the detection cycle and improves the detection efficiency. It is particularly suitable for scenarios that require frequent detection or emergency inspection.

[0018] (2) Accurately locate cracks: By precisely controlling the delay time of the two fundamental waves, the mixing area of ​​the fundamental waves in the pointed rail can be flexibly adjusted. The relative nonlinear coefficients of different mixing areas can be calculated to accurately reflect the existence and location of the crack. This positioning method is not only highly accurate, but also can achieve a preliminary assessment of the depth and length of the crack, providing an important basis for subsequent repair work.

[0019] (3) Reduce misjudgment and missed detection: Traditional detection methods may lead to misjudgment or missed detection due to environmental factors, equipment accuracy and other limitations. The detection method based on nonlinear ultrasonic guided wave mixing method can eliminate external interference to a certain extent by calculating the relative nonlinear coefficient, thereby improving the accuracy and reliability of detection and reducing the possibility of misjudgment and missed detection.

[0020] (4) Non-destructive testing: This method does not cause any physical damage to the switch rail or affect its normal use. This not only reduces the safety risks during the testing process, but also avoids the additional costs and time consumption caused by the testing.

[0021] (5) Enhanced detection flexibility: By adjusting the delay time and the parameters of the excitation signal, the detection area and detection depth can be flexibly changed to meet the detection requirements of turnout point rails of different materials and structures. This flexibility makes this method have a wider application prospect and higher practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1ais a schematic diagram of a detection system provided in an embodiment of the present application;

[0024] Figure 1b It is a flow chart of steps S101-S103 of a method for detecting cracks in a turnout point rail based on nonlinear ultrasonic guided waves provided in an embodiment of the present application;

[0025] Figure 2 It is a schematic diagram of the position of the sinusoidal signal scanning probe provided in an embodiment of the present application;

[0026] Figure 3 is a damage threshold schematic diagram provided in an embodiment of the present application;

[0027] Figure 4 is a schematic diagram of a Hanning window modulation signal provided in an embodiment of the present application;

[0028] Figure 5 It is a schematic diagram of arrangement mode 1 provided in an embodiment of the present application;

[0029] Figure 6 This is a schematic diagram of dividing different mixing areas provided in an embodiment of the present application;

[0030] Figure 7 It is a schematic diagram of the relationship between the mixing area and the relative nonlinear coefficient provided in the embodiment of the present application;

[0031] Figure 8 This is a schematic diagram of opposite collinear mixing detection provided by an embodiment of the present application;

[0032] Fig. 9 This is a schematic diagram of the results of method 3 provided in the embodiment of the present application;

[0033] Fig.10 It is a flowchart of steps S201-S202 provided in an embodiment of the present application;

[0034] Fig.11 is a schematic structural diagram of a turnout point rail crack detection device based on nonlinear ultrasonic guided waves provided in an embodiment of the present application;

[0035] Fig.12 It is a schematic diagram of the composition structure of the electronic device provided in the embodiment of the present application. DETAILED DESCRIPTION

[0036] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0037] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0038] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0039] In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0040] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0042] During the implementation of the embodiments of the present application, the applicant discovered that the prior art has the following problems:

[0043] Traditional non-destructive testing methods for rails mainly include: magnetic particle testing, eddy current testing, magnetic flux leakage testing, machine vision testing, etc.

[0044] (1) Magnetic particle testing: It is a method that uses magnetic fields and magnetic forces to detect surface and near-surface cracks in materials. When magnetic materials such as rails are magnetized, their magnetic permeability is significantly higher than that of the surrounding air. If there are cracks or other defects, the magnetic field lines will bend, resulting in leakage flux and local magnetic poles at the cracks. During magnetic particle testing, a medium composed of ferromagnetic particles is spread. These particles are attracted by the leakage flux and aggregate, which can intuitively show the location and approximate size of the cracks.

[0045] (2) Eddy current testing: It is a non-contact measurement technology. This detection method is mainly suitable for conductive materials and can effectively detect surface and near-surface structural defects and damage of conductive materials.

[0046] (3) Magnetic flux leakage detection: It is a method of detecting rail surface defects by using a strong magnetic field. First, the rail is magnetized. When there are cracks or other defects on the rail surface, these discontinuities will cause disturbances in the local magnetic field. The magnetic field signals leaking from the rail defects can be captured by using Hall effect sensors. By analyzing the captured magnetic field signals, the shape of the crack can be inferred.

[0047] (4) Visual inspection: It is a method of inspecting the object using human eyes or industrial cameras. It is mainly used to detect defects on the surface of workpieces. Machine vision inspection can accurately locate the defect position and identify the defect category.

[0048] At present, all the inspection equipment for cracks in railway rails is developed based on the ultrasonic body wave method, which mainly uses large flaw detection vehicles and supplemented by small flaw detectors to detect flaws in rails. The effective area of ​​ultrasonic body wave detection is the limited area scanned by the sound beam below the sensor. It requires the sensor to be continuously moved to complete data collection and then complete the detection of the entire component. The corresponding ultrasonic guided wave detection method has the advantages of wide coverage, long propagation distance and fast propagation speed, and is suitable for real-time online monitoring.

[0049] The traditional linear ultrasonic guided wave detection process based on ultrasonic guided waves first transmits the ultrasonic guided waves into the rail through an ultrasonic probe. When it encounters defects during the propagation process, an echo will be generated. Finally, the ultrasonic probe collects the signal and processes it to obtain information related to the defect.

[0050] However, magnetic particle testing, magnetic flux leakage testing, eddy current testing and machine vision testing can only detect cracks on the surface or near the surface of the rail, but cannot detect internal cracks. Rail flaw detection based on ultrasonic body waves cannot detect the entire cross-section of the rail at a long distance. Placing the probe at a certain position on the point rail cannot cover the entire point rail. Since the point rail is a variable-section component, the ultrasonic guided wave mode changes during the propagation process due to its dispersion characteristics, and the mode becomes extremely complex, resulting in the inability of the propagation linear ultrasonic guided wave detection method to distinguish between normal signals and defect signals.

[0051] In view of this, an embodiment of the present application provides a method for detecting cracks in a turnout rail based on nonlinear ultrasonic guided waves. Based on the nonlinear ultrasonic guided wave method, long-distance flaw detection of cracks in a turnout rail is achieved, and crack identification and positioning are achieved.

[0052] Before describing the embodiments of the present application, the theoretical basis used in the embodiments of the present application will first be explained.

[0053] Theoretical basis: There are two main sources for introducing nonlinear acoustic problems in solid media: classical nonlinearity and nonclassical nonlinearity. Classical nonlinearity is also called nonlinear elasticity, that is, the geometric nonlinearity and material nonlinearity of solid media. The stress-strain relationship here is considered to be a nonlinear relationship, and the definition is as follows:

[0054] σ=Eε(1+βε+...)

[0055] Among them, E is the elastic modulus, β is the second-order nonlinear coefficient, σ is the stress, and ε is the strain.

[0056] For non-classical nonlinearity, its source is mainly microscopic defects in solid media, which can be described by establishing relevant defect models. The developed theoretical models mainly include Hertz contact theory, hysteresis model theory and contact acoustic nonlinear theory (CAN), etc. Among them, the contact acoustic nonlinear (CAN) theory: due to the interaction between elastic waves and defective interfaces, the stiffness of the local area changes, and the corresponding bilinear stress-strain constitutive model is established.

[0057] When an ultrasonic wave of a certain frequency propagates in a medium, the crack alternately opens and closes during the process of passing through the crack, which is called a "breathing crack". The modulation effect of the ultrasonic guided wave through the crack causes the ultrasonic guided wave to be distorted. Due to the existence of contact acoustic nonlinearity (CAN), two fundamental wave signals with different excitation frequencies are used. In an undamaged specimen, when the two fundamental waves meet, since the intact material is approximately a linear elastic medium, the wave equation of the elastic wave is regarded as a linear equation. At this time, the two fundamental waves will not interact with each other and no mixing phenomenon will occur. However, when the material has damage such as plastic deformation and cracks, the nonlinear effect in the material will be significantly enhanced. In the damaged area, when the two waves meet, sum frequency waves or difference frequency waves will be generated. These newly generated waves contain relevant information reflecting the damage state of the material.

[0058] Relative nonlinear coefficient: When a solid medium is excited by multiple sound waves of different frequencies at the same time, a mixed sound field will be generated in the medium. The nonlinearity of the medium will be manifested through linear modulation between waves of different frequencies. By using two harmonic excitations of different frequencies and considering only the second-order nonlinear coefficient, the approximate solution of the nonlinear ultrasonic wave dynamic equation is obtained as follows:

[0059]

[0060] From the frequency component point of view, in addition to the fundamental wave components of ω1 and ω2, there are also the double frequency components of 2ω1 and 2ω2, as well as the difference frequency and sum frequency components of ω1-ω2 and ω1+ω2. The calculation formula of the nonlinear coefficient is obtained:

[0061]

[0062] Furthermore, considering only the amplitude-related components, the relative nonlinear coefficient formula is obtained:

[0063]

[0064] Therefore, when two fundamental waves of different frequencies propagate in a solid, due to the nonlinear effect of the solid, the radiated sound wave contains not only the fundamental component and the second harmonic component, but also the sum frequency and difference frequency components generated by the interaction of the two fundamental frequency signals. By calculating the nonlinear coefficient, the amplitude of the second-order harmonic, sum frequency, and difference frequency wave signals in the measurement signal can be obtained, and then the damage of the medium can be quantitatively evaluated.

[0065] In this problem, we discuss the nonlinear effects of a solid medium when it is excited by two acoustic waves of different frequencies. This nonlinear effect manifests itself through the interaction between the waves of different frequencies, producing, in addition to the fundamental frequencies (ω1 and ω2), the harmonics (2ω1 and 2ω2) as well as the sum (ω1+ω2) and difference (ω1-ω2) frequencies.

[0066] The approximate solution u(x,t) of the nonlinear wave equation contains the linear part u(0) and the nonlinear part u(1). The linear part consists of two fundamental frequency waves, while the nonlinear part contains the double frequency and sum and difference frequency components. The specific form is as follows:

[0067] u(x,t)=u(0)+βu(1)

[0068] =A1cos(ω1τ)+A2cos(ω2τ)-βx[8A12k12cos(2ω1τ)+8A22k22cos(2ω2τ)]+βx[4A1

[0069] A2k1k2(cos((ω1-ω2)τ)-cos((ω1+ω2)τ))]

[0070] Among them, A1 and A2 are the amplitudes of the fundamental waves, k1 and k2 are the corresponding wave numbers, ω1 and ω2 are the angular frequencies, τ=t-cx is the delay time (c is the wave speed), and β is the second-order nonlinear coefficient.

[0071] In order to extract the nonlinear coefficient β from the experimental data, we can use the relationship between the amplitude of the sum frequency or difference frequency component and the amplitude of the fundamental frequency. Based on the solution of the nonlinear wave equation, we can derive the calculation formula of the nonlinear coefficient:

[0072] β=k1k2x4A(ω1)A(ω2)A(ω1±ω2)

[0073] Among them, A(ω1±ω2) is the amplitude of the sum or difference frequency component, and A(ω1) and A(ω2) are the amplitudes of the fundamental frequency component.

[0074] To simplify the calculation, we can define the relative nonlinear coefficient β*, which is only related to the amplitude ratio:

[0075] β*=A(ω1)A(ω2)A(ω1±ω2)

[0076] This relative nonlinear coefficient can be measured directly from experimental data without knowing the wave numbers k1, k2 or the propagation distance x.

[0077] By measuring the nonlinear coefficient (or relative nonlinear coefficient), we can quantitatively evaluate the damage of solid media. Because the nonlinear effect is usually related to the microstructural changes of the medium (such as cracks, dislocations, etc.), the change of the nonlinear coefficient can reflect the degree of damage to the medium. This method has broad application prospects in the field of nondestructive testing.

[0078] See also Figure 1a , Figure 1a is a schematic diagram of a detection system provided in an embodiment of the present application, such as Figure 1aAs shown, the signal excitation device is used to generate two columns of fundamental wave signals, which are applied to the point rail through the excitation transducer AB to realize the excitation of the two columns of fundamental wave signals; the signal receiving device receives the vibration signal in the point rail through the connection receiving transducer R, and realizes signal filtering and storage; the signal processing device is used to analyze the received signal, amplify the signal, filter the signal, and calculate the relative nonlinear coefficient through FFT spectrum analysis. Figure 1a In the figure, the detection object is the switch point rail, the left end is close to the tip, and the right end is close to the thick end.

[0079] See also Figure 1b , Figure 1b is a flow chart of steps S101-S103 of a turnout rail crack detection method based on nonlinear ultrasonic guided waves provided in an embodiment of the present application, which will be combined with Figure 1b Steps S101-S103 are shown for explanation.

[0080] In step S101, a first target fundamental wave signal acting on the turnout point rail is generated, wherein the first target fundamental wave signal includes a first fundamental wave signal and a second fundamental wave signal, the first fundamental wave signal and the second fundamental wave signal are continuously transmitted sine waves, the first fundamental wave signal and the second fundamental wave signal are transmitted simultaneously, and the transmission time length is greater than the transmission delay of the fundamental wave signal between the two end points of the turnout point rail.

[0081] In step S102, a vibration signal generated in the switch point rail is received.

[0082] In combination with steps S101-S102, the excitation frequencies of the signal excitation device are respectively f a and f b Two columns of sinusoidal signals are used to achieve continuous excitation.

[0083] In some embodiments, the signal source of the target fundamental wave signal is located at a side away from the tip of the switch point rail, and the receiving end of the vibration signal is located close to the signal source.

[0084] As an example, see Figure 2 , Figure 2 Schematic diagram of the position of the sinusoidal signal scanning probe provided in the embodiment of the present application. Figure 2As shown, since the rail surface deformation at the tip of the pointed rail is large and it is not easy to install the transducer, the two excitation transducers and the receiving transducer are installed on the side away from the tip of the pointed rail, and the installation of the probe is easy. The continuous excitation sinusoidal signal allows the two columns of fundamental wave signals to be fully mixed in the entire pointed rail. If there is a crack in the pointed rail, no matter where the microcrack is, the mixed wave can interact with the crack, and due to the existence of contact acoustic nonlinearity (CAN), combined harmonics (sum frequency and difference frequency) are generated. Therefore, steps S101-S102 can quickly scan the entire pointed rail to determine whether there are microcracks, which can save time in a large number of detection tasks.

[0085] In step S103, a first relative nonlinear coefficient is calculated for the vibration signal, and whether the switch point rail has a crack is determined based on a preset damage threshold; if the switch point rail has a crack, a second target fundamental wave signal acting on the switch point rail is generated, and a detection area in the switch point rail is detected by the second target fundamental wave signal, and a position of the crack in the switch point rail is determined based on the second relative nonlinear coefficient of the detection area, wherein the second target fundamental wave signal includes a third fundamental wave signal and a fourth fundamental wave signal, and the detection area is determined by changing the position of a mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the switch point rail.

[0086] In some embodiments, the damage threshold is calculated as follows:

[0087] Determine a point rail to be detected, perform multiple measurements on the point rail to be detected, and calculate the first relative nonlinear coefficient for each measurement;

[0088] Calculate the mean and standard deviation of the first relative nonlinear coefficient calculated for each measurement;

[0089] determining a confidence interval based on the mean and the standard deviation;

[0090] The upper limit of the confidence interval is taken as the damage threshold.

[0091] See also Figure 3 , Figure 3 is a schematic diagram of damage threshold provided in an embodiment of the present application, such as Figure 3 As shown, the healthy state is 3001, the damaged state is 3002, and the damage threshold is 3003.

[0092] The damage threshold of each pointed rail is different, so for any pointed rail, multiple experiments are performed to calculate the relative nonlinear coefficient, which is recorded as {x1, x2, ..., x n}. Now calculate the mean (μ) and standard deviation (σ) of the data:

[0093]

[0094] Determine the confidence interval as [μ-kσ, μ+kσ], and select the upper limit of the confidence interval as the threshold, that is:

[0095] T=μ+kσ

[0096] The value of k depends on the confidence level (95% confidence level corresponds to k=1.96, 99% confidence level corresponds to k=2.58).

[0097] In actual detection tasks, this threshold can be optimized by adjusting the k value. When a relative nonlinear coefficient higher than this threshold appears in the detection task, it is considered that the pointed rail is damaged.

[0098] Next, the objects determined to be unhealthy point rails are further inspected to locate the cracks.

[0099] In the theoretical study of ultrasonic guided waves, the general window function uses a raised cosine window, and the modulation formula is:

[0100]

[0101] In the formula, a0 is the weighting coefficient, f c is the center frequency, n is the number of cycles of the sine signal, when a0=0.5, it is called the Hanning window, such as Figure 4 The schematic diagram of the Hanning window modulated signal is shown in FIG.

[0102] The excitation frequencies of the signal excitation device are respectively f a and f b The sine signal modulated by the Hanning window is assumed to be u a and u b , the sum frequency or difference frequency signal generated by their interaction with the microcracks is u n The arrangement of the excitation transducer is divided into method 1, method 2 and method 3.

[0103] The following will describe method 1, method 2, and method 3 in detail.

[0104] Method 1:

[0105] In some embodiments, the signal sources of the third fundamental wave signal and the fourth fundamental wave signal are located on a side away from the tip of the turnout point rail, and the signal source of the third fundamental wave signal and the signal source of the fourth fundamental wave signal are located in the same vertical direction, and the receiving end of the vibration signal is located close to the third fundamental wave signal or the fourth fundamental wave signal.

[0106] See also Figure 5 , Figure 5 is a schematic diagram of arrangement mode 1 provided in an embodiment of the present application, such as Figure 5As shown, the excitation transducers A and B are located on the side away from the tip of the pointed rail and in the same vertical direction. Arrangement 1: Both excitation transducers are located on the side away from the tip of the pointed rail. The probe installation method is simple, and only one probe can be used to transmit two wave packet signals at the same position, so that the mixed position can be calculated more accurately. However, when the microcrack is at the tip of the pointed rail, the excitation and reception distances are too far from the crack, which may result in a weak received mixed signal.

[0107] In some embodiments, the third fundamental wave signal and the fourth fundamental wave signal are sinusoidal signals modulated by a Hanning window, and the detection area is determined by:

[0108] Determine a first relationship between the position of the mixing area and the delay time, wherein the mixing area is the meeting position of the third fundamental wave signal and the fourth fundamental wave signal, and the delay time is the time interval for respectively exciting the third fundamental wave signal and the fourth fundamental wave signal;

[0109] determining a plurality of mixed regions based on the first relationship;

[0110] The second relative nonlinear coefficient of each of the plurality of mixed regions is calculated, and the position of the crack in the switch point rail is determined as the peak value according to the variation of the second relative nonlinear coefficient in different mixed regions.

[0111] In some embodiments, the group velocity of the third fundamental wave signal is less than the group velocity of the fourth fundamental wave signal, and determining the first relationship between the position of the mixing area and the delay time includes:

[0112] exciting the third fundamental wave signal;

[0113] After the delay time, the fourth fundamental wave signal is excited;

[0114] Based on the fact that the displacements of the third fundamental wave signal and the fourth fundamental wave signal are equal when the fourth fundamental wave signal catches up with the third fundamental wave signal, determining a first function of the distance of the mixing area from the right end of the point rail with respect to the delay time;

[0115] The first relationship is determined based on the first function, wherein the first relationship represents that the position of the mixing area and the delay time are in a linear relationship.

[0116] In some embodiments, dividing the switch point rail into at least one mixed area based on the first relationship comprises:

[0117] The mixed area is distributed at a designated position in the switch point rail by adjusting the delay time;

[0118] The switch point rail is divided into at least one mixed area based on the designated position.

[0119] In combination with the above embodiment, the fundamental wave u a The group velocity is less than the fundamental wave u b , then the fundamental wave u is first excited at the right end of the pointed rail a , after a time of Δt, the fundamental wave u is excited again b , when the fundamental wave u b Catch up with Kibo a When , the displacements of the two fundamental waves are equal, then:

[0120] C ga (t m +Δt)=C gb t m

[0121] Among them, C ga and C gb are the group velocities of the two fundamental waves, t m is the fundamental wave u b Catch up with Kibo a Therefore, it can be concluded that the distance x between the mixing area of ​​the two baseband signals and the right end of the point track is a function of the delay time Δt, that is,

[0122]

[0123] It can be seen that the position of the mixing area of ​​the fundamental frequency wave is linearly related to the delay time. Therefore, the delay time can be adjusted so that the mixing area of ​​the two fundamental frequency waves is distributed at any position of the pointed rail. Based on this, the pointed rail is subdivided into different mixing areas, and it is assumed that there is a crack in a certain mixing area. The schematic diagram of dividing different mixing areas is as follows: Figure 6 shown.

[0124] By calculating the relative nonlinear coefficients of the received signals in different mixing areas, we can get a schematic diagram of the relationship between the mixing area and the relative nonlinear coefficient, as shown in Figure 7 It can be seen that when the two fundamental waves are mixed at the crack, a relative nonlinear coefficient peak appears. Further detection of the peak area can accurately locate the crack position.

[0125] Method 2:

[0126] In some embodiments, the signal sources of the third fundamental wave signal and the fourth fundamental wave signal are respectively located at two ends of the switch point rail, and the receiving end of the vibration signal is located near the right end of the switch point rail.

[0127] In some embodiments, the third fundamental wave signal and the fourth fundamental wave signal are sinusoidal signals modulated by a Hanning window, and the detection area is determined by:

[0128] Determine a second relationship between the position of the mixing area and the delay time, wherein the delay time is a time interval for respectively exciting the third fundamental wave signal and the fourth fundamental wave signal;

[0129] The mixed area is made to scan the switch point rail by adjusting the time interval, and during the scanning process, the second nonlinear coefficient of the mixed area is calculated in real time, and the position of the crack in the switch point rail is determined as the peak value through the change of the second relative nonlinear coefficient in different mixed areas.

[0130] In some embodiments, determining the second relationship between the position of the mixing area and the delay time includes:

[0131] Exciting any one of the third fundamental wave signal or the fourth fundamental wave signal, and exciting the other fundamental wave signal after the delay time has elapsed;

[0132] Determine a second function of the distance from the mixed area to one end of the switch point rail and the delay time based on the encounter time of the third fundamental wave signal and the fourth fundamental wave signal;

[0133] The second relationship is determined based on the second function.

[0134] In combination with the above embodiment, the collinear mixing detection is excited at the left and right ends of the pointed rail respectively, and the two excitation signals can be delayed respectively, so as to control the mixing area to realize the global scanning of the board. In this case, there is no strict requirement for the group velocity of the fundamental frequency wave. Assume that the excitation signals are applied to the left and right ends of the pointed rail at the initial moment, and the fundamental frequency u is applied to the left end. a , the fundamental wave u is applied to the right end b , then the time when the two fundamental waves meet is:

[0135]

[0136] In the formula, l is the distance between the two excitation ends, C ga is the fundamental wave u a The group velocity, C gb is the fundamental wave u b The group velocity.

[0137] If the fundamental wave u is excited at the left end of the pointed rail at the initial moment a , after Δt b After the moment, the fundamental wave u is excited at the right end of the pointed rail. b , then the time t at which they meet can be calculated as follows n1 :

[0138] C ga t n1 +Cgb (t n1 -Δt b )=l

[0139] Right now:

[0140]

[0141] The distance from the mixing area to the excitation point at the left end of the switch rail and the delay time Δt b The functional relationship can be expressed as follows:

[0142]

[0143] If the fundamental wave u is excited at the right end of the pointed rail at the initial moment b , after Δt a After the moment, the fundamental wave u is excited at the left end of the pointed rail. a , then the time t at which they meet can be calculated as follows n2 :

[0144] C gb t n2 +C ga (t n2 -Δt a )=l

[0145] Right now:

[0146]

[0147] The distance from the mixing area to the excitation point at the left end of the switch rail and the delay time Δt b The functional relationship can be expressed as follows:

[0148]

[0149] When the fundamental wave u is applied to the left and right ends of the pointed rail at the same time a and fundamental wave u b , the mixing area is roughly near the middle of the pointed track. When the left excitation signal u a Apply Δt a After the delay, the mixed area will move to the left end of the pointed track. On the contrary, when the right end excitation signal u b Apply Δt b After the delay, the mixed area will move to the right end of the pointed track. Based on this, by changing the delay time of the two excitation signals respectively, the mixed area can scan the entire pointed track. The schematic diagram of the opposite collinear mixing detection is shown in Figure 8 As shown in the figure. When there is a crack in the mixed area, the mixed wave will interact with the crack to produce an obvious mixed frequency signal, thus realizing the location of the microcracks in the pointed rail. Compared with the same direction collinear mixed frequency detection, the opposite direction collinear mixed frequency detection makes the location calculation of the microcracks more concise and clear.

[0150] The detection principle of method 2 is the same as that of method 1. By changing the mixing area of ​​the two signals, the relationship between the relative nonlinear coefficient and the mixing area is obtained to achieve the location of the crack. In method 2, the excitation transducers are located at both ends of the pointed rail, which shortens the distance from the crack to the excitation end and makes it easier to receive obvious mixing signals. However, it is not easy to install the probe at the tip of the pointed rail, and the installation is troublesome.

[0151] Method 3:

[0152] The above two implementations (method 1 and method 2) only distinguish the installation position of the transducer. The principle of locating cracks is based on finding the maximum value of the relative nonlinear coefficient. However, even for the same pointed rail, the damage threshold will be different if the installation position of the transducer is different. By introducing the damage threshold in the crack location stage, reliability can be improved, false alarms can be reduced, and sensitivity to the damage threshold in step 1 can be reduced. The installation position of the transducer is the same as that of implementation 1, and the calculation method of the damage threshold is the same as above. The damage threshold at different positions is calculated for different mixing positions obtained using the delay setting. The result diagram is shown in the figure below. Fig. 9 shown.

[0153] There are certain differences in the damage thresholds at different positions. When locating the crack position, it is not necessary to focus only on the peak position of the relative nonlinear coefficient. When a coefficient value exceeding the threshold appears at a certain position, the position can also be further subdivided into mixed positions for detection.

[0154] In some embodiments, see Fig.10 , Fig.10 It is a flowchart of steps S201-S202 provided in an embodiment of the present application. The method also includes steps S201-S202, which will be described in combination with each step.

[0155] In step S201, in response to an adjustment operation on the packet widths of the third fundamental wave signal and the fourth fundamental wave signal, a width of the mixed region is determined;

[0156] In step S202, the size or width of the detection area is determined based on the width of the mixed area.

[0157] Here, the embodiment of the present application allows the wave packet width of the third fundamental wave signal and the fourth fundamental wave signal to be adjusted. The wave packet width is an important parameter of the signal, which affects the propagation characteristics of the signal in the material and the interaction with damage such as cracks. In response to the adjustment operation of the wave packet width, the method can determine the width of the mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the turnout point rail. The width of the mixed area is a key area for signal interaction and nonlinear effects, which affects the effect and accuracy of crack detection. Based on the width of the mixed area, the method can further determine the size or width of the detection area. Generally speaking, the wider the mixed area, the more obvious the nonlinear effect, but it may also reduce the spatial resolution of the detection. Therefore, it is necessary to make a trade-off between size, width and spatial resolution according to actual application requirements.

[0158] In the above manner, by introducing the adjustment operation of the wave packet width and the step of determining the size or width based on the mixed area width, the method provides a more flexible and customizable detection strategy to meet the needs of different turnout point rails and crack detection tasks.

[0159] In summary, the embodiments of the present application have the following beneficial effects:

[0160] (1) Efficient and fast scanning: By using the signal excitation device to continuously emit sinusoidal signals and combining it with the nonlinear ultrasonic guided wave mixing method, the turnout point rail can be comprehensively and quickly scanned in a short period of time. This method greatly shortens the detection cycle and improves the detection efficiency. It is particularly suitable for scenarios that require frequent detection or emergency inspection.

[0161] (2) Accurately locate cracks: By precisely controlling the delay time of the two fundamental waves, the mixing area of ​​the fundamental waves in the pointed rail can be flexibly adjusted. The relative nonlinear coefficients of different mixing areas can be calculated to accurately reflect the existence and location of the crack. This positioning method is not only highly accurate, but also can achieve a preliminary assessment of the depth and length of the crack, providing an important basis for subsequent repair work.

[0162] (3) Reduce misjudgment and missed detection: Traditional detection methods may lead to misjudgment or missed detection due to environmental factors, equipment accuracy and other limitations. The detection method based on nonlinear ultrasonic guided wave mixing method can eliminate external interference to a certain extent by calculating the relative nonlinear coefficient, thereby improving the accuracy and reliability of detection and reducing the possibility of misjudgment and missed detection.

[0163] (4) Non-destructive testing: This method does not cause any physical damage to the switch rail or affect its normal use. This not only reduces the safety risks during the testing process, but also avoids the additional costs and time consumption caused by the testing.

[0164] (5) Enhanced detection flexibility: By adjusting the delay time and the parameters of the excitation signal, the detection area and detection depth can be flexibly changed to meet the detection requirements of turnout point rails of different materials and structures. This flexibility makes this method have a wider application prospect and higher practical value.

[0165] Based on the same inventive concept, the embodiments of the present application also provide a turnout point rail crack detection device based on nonlinear ultrasonic guided waves corresponding to the turnout point rail crack detection method based on nonlinear ultrasonic guided waves in the first embodiment. Since the principle of solving the problem by the device in the embodiments of the present application is similar to the above-mentioned turnout point rail crack detection method based on nonlinear ultrasonic guided waves, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0166] like Fig.11 As shown, Fig.11 : is a schematic diagram of the structure of a switch rail crack detection device 300 based on nonlinear ultrasonic guided waves provided in an embodiment of the present application. The switch rail crack detection device 300 based on nonlinear ultrasonic guided waves includes:

[0167] A signal excitation device 301 is used to generate a first target fundamental wave signal acting on the switch rail, wherein the first target fundamental wave signal includes a first fundamental wave signal and a second fundamental wave signal, the first fundamental wave signal and the second fundamental wave signal are continuously transmitted sine waves, the first fundamental wave signal and the second fundamental wave signal are transmitted simultaneously, and the transmission time length is greater than the transmission delay of the fundamental wave signal between the two end points of the switch rail; and when there is a crack in the switch rail, generate a second target fundamental wave signal acting on the switch rail, wherein the second target fundamental wave signal includes a third fundamental wave signal and a fourth fundamental wave signal;

[0168] A signal receiving device 302, used to receive a vibration signal generated in the switch point rail;

[0169] The signal processing device 303 is used to calculate a first relative nonlinear coefficient for the vibration signal, and determine whether there is a crack in the switch point rail based on a preset damage threshold; and when there is a crack in the switch point rail, detect a detection area in the switch point rail through the second target fundamental wave signal, and determine the position of the crack in the switch point rail based on the second relative nonlinear coefficient of the detection area, wherein the detection area is determined by changing the position of a mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the switch point rail.

[0170] Those skilled in the art should understand that Fig.11 The functions of the various units in the switch point rail crack detection device 300 based on nonlinear ultrasonic guided waves can be understood by referring to the related description of the switch point rail crack detection method based on nonlinear ultrasonic guided waves mentioned above. Fig.11 The functions of the various units in the switch point rail crack detection device 300 based on nonlinear ultrasonic guided waves shown can be implemented by a program running on a processor, or by a specific logic circuit.

[0171] In a possible implementation manner, a signal source of the first target fundamental wave signal is located at a side away from the tip of the switch point rail, and a receiving end of the vibration signal is located close to the signal source.

[0172] In a possible implementation, the damage threshold is calculated in the following manner:

[0173] Determine a point rail to be detected, perform multiple measurements on the point rail to be detected, and calculate the first relative nonlinear coefficient for each measurement;

[0174] Calculate the mean and standard deviation of the first relative nonlinear coefficient calculated for each measurement;

[0175] determining a confidence interval based on the mean and the standard deviation;

[0176] The upper limit of the confidence interval is taken as the damage threshold.

[0177] In a possible implementation, the signal sources of the third fundamental wave signal and the fourth fundamental wave signal are located on a side away from the tip of the turnout point rail, and the signal source of the third fundamental wave signal and the signal source of the fourth fundamental wave signal are located in the same vertical direction, and the receiving end of the vibration signal is located close to the third fundamental wave signal or the fourth fundamental wave signal.

[0178] In a possible implementation manner, the third fundamental wave signal and the fourth fundamental wave signal are sinusoidal signals modulated by a Hanning window, and the detection area is determined by:

[0179] Determine a first relationship between the position of the mixing area and the delay time, wherein the mixing area is the meeting position of the third fundamental wave signal and the fourth fundamental wave signal, and the delay time is the time interval for respectively exciting the third fundamental wave signal and the fourth fundamental wave signal;

[0180] determining a plurality of mixed regions based on the first relationship;

[0181] The second relative nonlinear coefficient of each of the plurality of mixed regions is calculated, and the position of the crack in the switch point rail is determined as the peak value according to the variation of the second relative nonlinear coefficient in different mixed regions.

[0182] In a possible implementation manner, the group velocity of the third fundamental wave signal is less than the group velocity of the fourth fundamental wave signal, and the signal processing device 303 determines the first relationship between the position of the mixing area and the delay time, including:

[0183] exciting the third fundamental wave signal;

[0184] After the delay time, the fourth fundamental wave signal is excited;

[0185] Based on the fact that the displacements of the third fundamental wave signal and the fourth fundamental wave signal are equal when the fourth fundamental wave signal catches up with the third fundamental wave signal, determining a first function of the distance of the mixing area from the right end of the point rail with respect to the delay time;

[0186] The first relationship is determined based on the first function, wherein the first relationship represents that the position of the mixing area and the delay time are in a linear relationship.

[0187] In a possible implementation manner, the signal processing device 303 divides the turnout point rail into at least one mixed area based on the first relationship, including:

[0188] The mixed area is distributed at a designated position in the switch point rail by adjusting the delay time;

[0189] The switch point rail is divided into at least one mixed area based on the designated position.

[0190] In a possible implementation manner, the signal sources of the third fundamental wave signal and the fourth fundamental wave signal are respectively located at two ends of the switch point rail, and the receiving end of the vibration signal is located near the right end of the switch point rail.

[0191] In a possible implementation manner, the third fundamental wave signal and the fourth fundamental wave signal are sinusoidal signals modulated by a Hanning window, and the detection area is determined by:

[0192] Determine a second relationship between the position of the mixing area and the delay time, wherein the delay time is a time interval for respectively exciting the third fundamental wave signal and the fourth fundamental wave signal;

[0193] The mixed area is made to scan the switch point rail by adjusting the time interval, and during the scanning process, the second nonlinear coefficient of the mixed area is calculated in real time, and the position of the crack in the switch point rail is determined as the peak value through the change of the second relative nonlinear coefficient in different mixed areas.

[0194] In a possible implementation manner, the signal processing device 303 determines the second relationship between the position of the mixed area and the delay time, including:

[0195] Exciting any one of the third fundamental wave signal or the fourth fundamental wave signal, and exciting the other fundamental wave signal after the delay time has elapsed;

[0196] Determine a second function of the distance from the mixed area to one end of the switch point rail and the delay time based on the encounter time of the third fundamental wave signal and the fourth fundamental wave signal;

[0197] The second relationship is determined based on the second function.

[0198] In a possible implementation manner, the third fundamental wave signal is close to the left end of the switch rail, the fourth fundamental wave signal is close to the right end of the switch rail, and the signal processing device 303 adjusts the time interval so that the mixed area scans the switch rail, including:

[0199] The mixing area is moved to the right by exciting the third fundamental wave signal and then exciting the fourth fundamental wave signal after the time interval, or is moved to the left by exciting the fourth fundamental wave signal and then exciting the third fundamental wave signal after the time interval, until the mixing area scans the entire switch point rail.

[0200] In a possible implementation manner, the signal excitation device 301 further includes:

[0201] determining the width of the mixed region in response to an adjustment operation on the width of the wave packets of the third fundamental wave signal and the fourth fundamental wave signal;

[0202] The size or width of the detection region is determined based on the width of the mixed region.

[0203] The above-mentioned turnout point rail crack detection device based on nonlinear ultrasonic guided waves has the following beneficial effects:

[0204] (1) Efficient and fast scanning: By using the signal excitation device to continuously emit sinusoidal signals and combining it with the nonlinear ultrasonic guided wave mixing method, the turnout point rail can be comprehensively and quickly scanned in a short period of time. This method greatly shortens the detection cycle and improves the detection efficiency. It is particularly suitable for scenarios that require frequent detection or emergency inspection.

[0205] (2) Accurately locate cracks: By precisely controlling the delay time of the two fundamental waves, the mixing area of ​​the fundamental waves in the pointed rail can be flexibly adjusted. The relative nonlinear coefficients of different mixing areas can be calculated to accurately reflect the existence and location of the crack. This positioning method is not only highly accurate, but also can achieve a preliminary assessment of the depth and length of the crack, providing an important basis for subsequent repair work.

[0206] (3) Reduce misjudgment and missed detection: Traditional detection methods may lead to misjudgment or missed detection due to environmental factors, equipment accuracy and other limitations. The detection method based on nonlinear ultrasonic guided wave mixing method can eliminate external interference to a certain extent by calculating the relative nonlinear coefficient, thereby improving the accuracy and reliability of detection and reducing the possibility of misjudgment and missed detection.

[0207] (4) Non-destructive testing: This method does not cause any physical damage to the switch rail or affect its normal use. This not only reduces the safety risks during the testing process, but also avoids the additional costs and time consumption caused by the testing.

[0208] (5) Enhanced detection flexibility: By adjusting the delay time and the parameters of the excitation signal, the detection area and detection depth can be flexibly changed to meet the detection requirements of turnout point rails of different materials and structures. This flexibility makes this method have a wider application prospect and higher practical value.

[0209] like Fig.12 As shown, Fig.12 The present invention provides a schematic diagram of the structure of an electronic device 400, wherein the electronic device 400 includes:

[0210] A processor 401, a storage medium 402 and a bus 403, wherein the storage medium 402 stores machine-readable instructions executable by the processor 401. When the electronic device 400 is running, the processor 401 communicates with the storage medium 402 via the bus 403, and the processor 401 executes the machine-readable instructions to perform the steps of the turnout point rail crack detection method based on nonlinear ultrasonic guided waves described in the embodiment of the present application.

[0211] In actual application, the components in the electronic device 400 are coupled together via the bus 403. It is understood that the bus 403 is used to realize the connection and communication between these components. In addition to the data bus, the bus 403 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, Fig.12 Various buses are labeled as bus 403.

[0212] The above electronic device has the following beneficial effects:

[0213] (1) Efficient and fast scanning: By using the signal excitation device to continuously emit sinusoidal signals and combining it with the nonlinear ultrasonic guided wave mixing method, the turnout point rail can be comprehensively and quickly scanned in a short period of time. This method greatly shortens the detection cycle and improves the detection efficiency. It is particularly suitable for scenarios that require frequent detection or emergency inspection.

[0214] (2) Accurately locate cracks: By precisely controlling the delay time of the two fundamental waves, the mixing area of ​​the fundamental waves in the pointed rail can be flexibly adjusted. The relative nonlinear coefficients of different mixing areas can be calculated to accurately reflect the existence and location of the crack. This positioning method is not only highly accurate, but also can achieve a preliminary assessment of the depth and length of the crack, providing an important basis for subsequent repair work.

[0215] (3) Reduce misjudgment and missed detection: Traditional detection methods may lead to misjudgment or missed detection due to environmental factors, equipment accuracy and other limitations. The detection method based on nonlinear ultrasonic guided wave mixing method can eliminate external interference to a certain extent by calculating the relative nonlinear coefficient, thereby improving the accuracy and reliability of detection and reducing the possibility of misjudgment and missed detection.

[0216] (4) Non-destructive testing: This method does not cause any physical damage to the switch rail or affect its normal use. This not only reduces the safety risks during the testing process, but also avoids the additional costs and time consumption caused by the testing.

[0217] (5) Enhanced detection flexibility: By adjusting the delay time and the parameters of the excitation signal, the detection area and detection depth can be flexibly changed to meet the detection requirements of turnout point rails of different materials and structures. This flexibility makes this method have a wider application prospect and higher practical value.

[0218] The embodiment of the present application further provides a computer-readable storage medium, which stores executable instructions. When the executable instructions are executed by at least one processor 401, the turnout point rail crack detection method based on nonlinear ultrasonic guided waves described in the embodiment of the present application is implemented.

[0219] In some embodiments, the storage medium can be a magnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface storage, an optical disk, or a compact disc read-only memory (CDROM); it can also be various devices including one or any combination of the above memories.

[0220] In some embodiments, executable instructions may be in the form of a program, software, software module, script or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0221] As an example, executable instructions may, but do not necessarily, correspond to a file in a file system, may be stored as part of a file that stores other programs or data, for example, in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple coordinated files (for example, files storing one or more modules, subroutines, or code portions).

[0222] By way of example, executable instructions may be deployed to be executed on one computing device, or on multiple computing devices located at one site, or on multiple computing devices distributed across multiple sites and interconnected by a communication network.

[0223] The computer-readable storage medium has the following advantages:

[0224] (1) Efficient and fast scanning: By using the signal excitation device to continuously emit sinusoidal signals and combining it with the nonlinear ultrasonic guided wave mixing method, the turnout point rail can be comprehensively and quickly scanned in a short period of time. This method greatly shortens the detection cycle and improves the detection efficiency. It is particularly suitable for scenarios that require frequent detection or emergency inspection.

[0225] (2) Accurately locate cracks: By precisely controlling the delay time of the two fundamental waves, the mixing area of ​​the fundamental waves in the pointed rail can be flexibly adjusted. The relative nonlinear coefficients of different mixing areas can be calculated to accurately reflect the existence and location of the crack. This positioning method is not only highly accurate, but also can achieve a preliminary assessment of the depth and length of the crack, providing an important basis for subsequent repair work.

[0226] (3) Reduce misjudgment and missed detection: Traditional detection methods may lead to misjudgment or missed detection due to environmental factors, equipment accuracy and other limitations. The detection method based on nonlinear ultrasonic guided wave mixing method can eliminate external interference to a certain extent by calculating the relative nonlinear coefficient, thereby improving the accuracy and reliability of detection and reducing the possibility of misjudgment and missed detection.

[0227] (4) Non-destructive testing: This method does not cause any physical damage to the switch rail or affect its normal use. This not only reduces the safety risks during the testing process, but also avoids the additional costs and time consumption caused by the testing.

[0228] (5) Enhanced detection flexibility: By adjusting the delay time and the parameters of the excitation signal, the detection area and detection depth can be flexibly changed to meet the detection requirements of turnout point rails of different materials and structures. This flexibility makes this method have a wider application prospect and higher practical value.

[0229] In the several embodiments provided in the present application, it should be understood that the disclosed methods and electronic devices can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0230] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0231] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0232] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a platform server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks, or optical disks.

[0233] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for detecting cracks in turnout point rails based on nonlinear ultrasonic guided waves, characterized in that: The method comprises: Generate a first target fundamental wave signal acting on the switch point rail, wherein the first target fundamental wave signal includes a first fundamental wave signal and a second fundamental wave signal, the first fundamental wave signal and the second fundamental wave signal are continuously transmitted sine waves, the first fundamental wave signal and the second fundamental wave signal are transmitted simultaneously, and the transmission time length is greater than the transmission delay of the fundamental wave signal between the two end points of the switch point rail; receiving a vibration signal generated in the switch point rail; A first relative nonlinear coefficient is calculated for the vibration signal, and whether the switch point rail has a crack is determined based on a preset damage threshold; if the switch point rail has a crack, a second target fundamental wave signal acting on the switch point rail is generated, and a detection area in the switch point rail is detected by the second target fundamental wave signal, and the position of the crack in the switch point rail is determined based on the second relative nonlinear coefficient of the detection area, wherein the second target fundamental wave signal includes a third fundamental wave signal and a fourth fundamental wave signal, and the detection area is determined by changing the position of a mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the switch point rail.

2. The method according to claim 1, characterized in that The signal source of the first target fundamental wave signal is located at a side away from the tip of the turnout point rail, and the receiving end of the vibration signal is located close to the signal source.

3. The method according to claim 1, characterized in that The damage threshold is calculated as follows: Determine a point rail to be detected, perform multiple measurements on the point rail to be detected, and calculate the first relative nonlinear coefficient for each measurement; Calculate the mean and standard deviation of the first relative nonlinear coefficient calculated for each measurement; determining a confidence interval based on the mean and the standard deviation; The upper limit of the confidence interval is taken as the damage threshold.

4. The method according to claim 1, characterized in that The signal sources of the third fundamental wave signal and the fourth fundamental wave signal are located on a side away from the tip of the turnout point rail, and the signal source of the third fundamental wave signal and the signal source of the fourth fundamental wave signal are located in the same vertical direction, and the receiving end of the vibration signal is located close to the third fundamental wave signal or the fourth fundamental wave signal.

5. The method according to claim 4, characterized in that The third fundamental wave signal and the fourth fundamental wave signal are sinusoidal signals modulated by a Hanning window, and the detection area is determined by: Determine a first relationship between the position of the mixing area and the delay time, wherein the mixing area is the meeting position of the third fundamental wave signal and the fourth fundamental wave signal, and the delay time is the time interval for respectively exciting the third fundamental wave signal and the fourth fundamental wave signal; determining a plurality of mixed regions based on the first relationship; The second relative nonlinear coefficient of each of the plurality of mixed regions is calculated, and the position of the crack in the switch point rail is determined as the peak value according to the variation of the second relative nonlinear coefficient in different mixed regions.

6. The method according to claim 5, characterized in that The group velocity of the third fundamental wave signal is less than the group velocity of the fourth fundamental wave signal, and the determining of the first relationship between the position of the mixing area and the delay time includes: exciting the third fundamental wave signal; After the delay time, the fourth fundamental wave signal is excited; Based on the fact that the displacements of the third fundamental wave signal and the fourth fundamental wave signal are equal when the fourth fundamental wave signal catches up with the third fundamental wave signal, determining a first function of the distance of the mixing area from the right end of the point rail with respect to the delay time; The first relationship is determined based on the first function, wherein the first relationship represents that the position of the mixing area and the delay time are in a linear relationship.

7. The method according to claim 5, characterized in that The step of dividing the switch rail into at least one mixed area based on the first relationship comprises: The mixed area is distributed at a designated position in the switch point rail by adjusting the delay time; The switch point rail is divided into at least one mixed area based on the designated position.

8. The method according to claim 1, characterized in that The signal sources of the third fundamental wave signal and the fourth fundamental wave signal are respectively located at two ends of the switch point rail, and the receiving end of the vibration signal is located near the right end of the switch point rail.

9. The method according to claim 8, characterized in that The third fundamental wave signal and the fourth fundamental wave signal are sinusoidal signals modulated by a Hanning window, and the detection area is determined by: Determine a second relationship between the position of the mixing area and the delay time, wherein the delay time is a time interval for respectively exciting the third fundamental wave signal and the fourth fundamental wave signal; The mixed area is made to scan the switch point rail by adjusting the time interval, and during the scanning process, the second nonlinear coefficient of the mixed area is calculated in real time, and the position of the crack in the switch point rail is determined as the peak value through the change of the second relative nonlinear coefficient in different mixed areas.

10. The method according to claim 9, characterized in that Determining the second relationship between the position of the mixing area and the delay time includes: Exciting any one of the third fundamental wave signal or the fourth fundamental wave signal, and exciting the other fundamental wave signal after the delay time has elapsed; Determine a second function of the distance from the mixed area to one end of the switch point rail and the delay time based on the encounter time of the third fundamental wave signal and the fourth fundamental wave signal; The second relationship is determined based on the second function.

11. The method according to claim 9, characterized in that The third fundamental wave signal is close to the left end of the switch rail, the fourth fundamental wave signal is close to the right end of the switch rail, and the time interval is adjusted so that the mixed area scans the switch rail, including: The mixing area is moved to the right by exciting the third fundamental wave signal and then exciting the fourth fundamental wave signal after the time interval, or is moved to the left by exciting the fourth fundamental wave signal and then exciting the third fundamental wave signal after the time interval, until the mixing area scans the entire switch point rail.

12. The method according to any one of claims 5-7 or 9-11, characterized in that: The method further comprises: determining the width of the mixed region in response to an adjustment operation on the width of the wave packets of the third fundamental wave signal and the fourth fundamental wave signal; The size or width of the detection region is determined based on the width of the mixed region.

13. A turnout rail crack detection device based on nonlinear ultrasonic guided waves, characterized in that: The device comprises: A signal excitation device, used for generating a first target fundamental wave signal acting on the switch point rail, wherein the first target fundamental wave signal includes a first fundamental wave signal and a second fundamental wave signal, the first fundamental wave signal and the second fundamental wave signal are continuously transmitted sine waves, the first fundamental wave signal and the second fundamental wave signal are transmitted simultaneously, and the transmission time length is greater than the transmission delay of the fundamental wave signal between the two end points of the switch point rail; and when there is a crack in the switch point rail, generating a second target fundamental wave signal acting on the switch point rail, wherein the second target fundamental wave signal includes a third fundamental wave signal and a fourth fundamental wave signal; A signal receiving device, used for receiving a vibration signal generated in the switch point rail; A signal processing device, used for calculating a first relative nonlinear coefficient for the vibration signal, and determining whether there is a crack in the switch point rail based on a preset damage threshold; and when there is a crack in the switch point rail, detecting a detection area in the switch point rail by using the second target fundamental wave signal, and determining the position of the crack in the switch point rail based on the second relative nonlinear coefficient of the detection area, wherein the detection area is determined by changing the position of a mixed area of ​​the third fundamental wave signal and the fourth fundamental wave signal in the switch point rail.

14. An electronic device, characterized in that: include: A processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the storage medium via the bus, and the processor executes the machine-readable instructions to execute the turnout point rail crack detection method based on nonlinear ultrasonic guided waves as described in any one of claims 1 to 12.

15. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for detecting cracks in a turnout point rail based on nonlinear ultrasonic guided waves according to any one of claims 1 to 12 is executed.

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