CN117517478A - Method, system and equipment for quantifying buried depth of buried defect of rail web of steel rail - Google Patents
Method, system and equipment for quantifying buried depth of buried defect of rail web of steel rail Download PDFInfo
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Abstract
The invention discloses a method, a system and equipment for quantifying the burial depth of a rail web burial defect of a steel rail, and relates to the field of nondestructive detection. According to the method, SH0, SH1 and SH2 modes of the excited SH guided waves are taken as research objects, so that dispersion curves of the guided waves of different modes are obtained; then calculating normalized distribution conditions of displacement fields and energy fields of different guided wave orders to obtain corresponding relations of reflected guided wave energy of defects under different normal deviations, and further obtaining normalized E-s curves of guided waves of all modes; then calculating the specific order coefficient G of the position of the equal energy point and the guided waves of different modes roc Relationship between them, control G roc The s-plot allows the determination of the normal offset s of the buried defect. The invention canAs an important supplement to ultrasonic guided wave rail defect quantification technology, the method can realize depth quantification and high-precision evaluation of normal deviation of the buried defect under the condition of no-defect baseline signals, and is particularly suitable for nondestructive detection of the buried defect of the rail network.
Description
Technical Field
The invention relates to the technical field of nondestructive testing, in particular to a method, a system and equipment for quantifying the burial depth of a rail web burial defect of a steel rail.
Background
The rapid development of railways provides a convenient transportation means for people and becomes an important high-efficiency carrier for transporting bulk cargoes. In addition, the railway has the advantages of small climate influence, strong transportation capability, good energy saving performance and the like. Rails are an important component of railway systems. They directly bear the load transmitted by the wheel set and often operate in extreme environments such as high temperature, high speed, reciprocating impact, sudden temperature changes, etc. Therefore, along with the continuous deterioration of the external environment, the bearing capacity is gradually improved, and the steel rail is inevitably aged and damaged along with the increase of the service life, so that the safe running of the train is seriously threatened. Typical rail defects include surface cracks, screw hole cracks, localized corrosion, scale marks, compound cracks, and the like, distributed at the head, waist, bottom of the rail. However, internal buried defects tend to be more difficult to find than these more pronounced external defects, and may already exist at the time of rail manufacture. Unlike the heads and feet which are prone to wear, the relatively thin web is more prone to internal fatigue cracking due to the greater amplitude of reciprocation impact that occurs as the train passes. Most of the existing detection technologies are sensitive to rail head and rail bottom defects, and less research is conducted on detection and quantitative characterization of rail web internal defects. Therefore, an effective nondestructive testing method is highly desirable to achieve high sensitivity and high accuracy quantification of buried rail web defects.
Locating and quantifying a rail embedded defect involves 6 dimensions of information including the length, width, depth of the defect itself, axial distance, circumferential distance related to the location of the defect, and normal offset (also the depth of the defect). The existing ultrasonic guided wave defect detection method can realize quantification of the first five dimensions, such as: length quantization is related to defect axial reflection, width quantization is related to multichannel position of highest intensity signal, depth is related to signal intensity of reflected wave and transmitted wave; the defect axial distance is related to the travel time and wave speed of the guided wave, and the circumferential distance is related to the multi-channel guided wave amplitude ratio. At present, no better method is available for determining the normal offset of the embedded defect, the physical quantity is related to the embedded depth of the invisible defect, and judging whether the embedded defect is located near the surface or in the depth of the sample is one of the challenges faced by the existing ultrasonic nondestructive testing technology.
Currently, manual inspection is the most commonly used method for detecting rail defects. However, this method is inefficient, time consuming, labor intensive, and relies on subjective judgment by experienced inspectors. In contrast, popular machine vision methods, such as traditional image processing and deep learning, can identify most defects with very high efficiency and without operator intervention. However, the image generated by this method is based on a high-speed camera scan, does not contain information about buried defects, and the method is only sensitive to surface defects. Therefore, various nondestructive testing techniques, particularly physical testing methods, are more suitable choices. One common method is to analyze the difference in light passing through the rail using radiation detection to determine if defects are present, based on the difference in radiation penetration of different object densities. However, the radiation detection equipment is often very large, and on-line detection of the steel rail is difficult to realize, so that the radiation detection equipment is mainly used for quality control in the steel rail production process. Another common method is eddy current detection, which includes conventional techniques, far field techniques, pulsed techniques, multi-frequency techniques, and the like. These methods typically use the change in impedance of the induction coil to detect irregularities in the rail surface and obtain location and magnitude information of the defect by analyzing the characteristics of the received signal. However, the eddy current detection method is greatly affected by the lift-off distance, and is not easy to apply to the on-line detection of the high-speed train with strong vibration. Furthermore, eddy current detection is relatively sensitive to surface defects, and detection of internal defects requires a reduction in excitation frequency, which has some effect on detection sensitivity. In addition, there is also leakage detection that detects defects by using a leakage magnetic field generated by a magnetized object in the vicinity of a surface defect, and collects leakage magnetic signals by a magnetic sensor chip. However, the leakage magnetic detection is difficult to be used for on-line detection of a high-speed vehicle due to the influence of magnetization relaxation time and velocity effect, and the detection sensitivity for buried fine defects and circumferential cracks is low. In addition, there are other railway testing methods such as acoustic emissions, magnetic particles, infrared and alternating field measurements, but currently have less application in industry.
The existing ultrasonic guided wave detection method can only realize the preliminary positioning of defects, and is difficult to realize high-precision quantitative analysis. Although the defect length can be obtained by the travel time of the reflected wave at the interface, the defect width can be obtained by using a guided wave array, accurate quantification of the defect depth still faces challenges. In addition, the existing methods mainly rely on baseline signal subtraction or time domain inversion methods, which have low computational efficiency and lack accuracy in quantitative analysis capability. Secondly, the ultrasonic guided wave method has the advantages that the ultrasonic energy can cover the whole section of the sample and the single detection distance is longer, so that the ultrasonic guided wave method has potential in the aspects of buried defect detection and steel rail on-line monitoring. The method can evaluate the axial and circumferential distance of the defect. However, there is currently no effective method for quantifying the normal offset of defects, which limits the accurate assessment of the health of the rail.
Disclosure of Invention
Aiming at the problems in the background art, the invention provides a method, a system and equipment for quantifying the buried defect depth of a rail web of a steel rail, so as to realize depth quantification and high-precision evaluation of normal deviation of the buried defect under the condition of no-defect baseline signals.
In order to achieve the above object, the present invention provides the following solutions:
on one hand, the invention provides a method for quantifying the burial depth of a rail web burial defect of a steel rail, which comprises the following steps:
taking SH0, SH1 and SH2 modes of the excited SH guided waves as research objects, and obtaining dispersion curves of the guided waves of different modes;
calculating normalized energy distribution of the guided waves of different modes along the thickness direction of the steel rail sample based on the dispersion curves of the guided waves of different modes;
integrating normalized energy distribution of guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain the corresponding relation of reflected guided wave energy of the defect under different normal deviations;
after the depth of the defect and the thickness of the sample are determined, a normalized E-s curve of each mode guided wave is obtained according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations;
calculating the position of an equal energy point and the guided wave ratio order coefficient G of the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot;
control G roc -s-plot determining normal offset of buried defect.
Optionally, the obtaining the dispersion curve of the guided waves of different modes by using the SH0, SH1 and SH2 modes of the excited SH guided wave as the research object specifically includes:
simplifying a Navier motion displacement equation according to the displacement characteristic of the excited SH guided wave to obtain a simplified equation;
combining the real part of the simplified equation general solution with SH guided wave mode characteristics to obtain displacement field equations of symmetrical and antisymmetric modes;
according to displacement field equations of symmetrical and antisymmetric modes and free surface boundary conditions of the free boundary steel plate, obtaining dispersion equations of SH guided waves of the symmetrical and antisymmetric modes;
solving the dispersion equation, expressing the guided wave speed as a function of the frequency-thickness product, and drawing dispersion curves of three modal guided waves of SH0, SH1 and SH 2.
Optionally, calculating normalized energy distribution of different mode guided waves along the thickness direction of the steel rail sample based on the dispersion curve of the different mode guided waves specifically includes:
based on the dispersion curves of the guided waves of different modes, a formula is adoptedAlong rail sampleCalculating displacement fields of the guided waves of different modes in the thickness direction; wherein-> And->Respectively representing displacement fields of three modal guided waves of SH0, SH1 and SH2 along the thickness direction of the steel rail sample; a 'and B' are constant coefficients; t represents the thickness of the sample; z represents the coordinates of the sample in the thickness direction;
and calculating the normalized distribution of the energy field according to the displacement fields of the guided waves of different modes, so as to obtain the normalized energy distribution of the guided waves of different modes.
Optionally, integrating the normalized energy distribution of the guided waves of different modes along the upper and lower boundaries of the depth direction of the defect to obtain the corresponding relation of the reflected guided wave energy of the defect under different normal deviations, which specifically includes:
according to the formulaIntegrating normalized energy distribution of guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain the corresponding relation of reflected guided wave energy of the defect under different normal deviations; wherein E is SH0 、E SH1 And E is SH2 The guided wave energy of three modal guided waves of SH0, SH1 and SH2 are respectively represented; s is the normal offset of the defect; d is the defect depth.
Optionally, after the defect depth and the thickness of the sample are determined, a normalized E-s curve of each mode guided wave is obtained according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations, and specifically includes:
aiming at the determined defect depth d and sample thickness t of the steel rail sample, drawing normalized E-s curves of three mode guided waves of SH0, SH1 and SH2 in a segmented manner according to the corresponding relation of reflected guided wave energy of the defect under different normal deviations; the abscissa of the normalized E-s curve is normal offset, and the ordinate is guided wave energy.
Optionally, calculating the ratio coefficient G of the position of the equal energy point and the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot, comprising in particular:
calculating E according to normalized E-s curves of SH1 and SH2 mode guided waves SH2 ＝E SH1 Time-constant energy point s c Is a position of (2);
using the formula
Calculating the guided wave specific order coefficient G of the guided waves of different modes roc The method comprises the steps of carrying out a first treatment on the surface of the Wherein the method comprises the steps ofG representing second order guided wave roc G of value and first order guided wave roc A ratio of values; />G representing first order guided waves roc G of value and zero order guided wave roc A ratio of values;
taking the normal offset s as the abscissa, and taking the corresponding guided wave ratio order coefficientOr->As the ordinate, G is generated roc -s-plot.
On the other hand, the invention also provides a rail web embedded defect embedded depth quantification system, which comprises:
the dispersion curve drawing module is used for taking SH0, SH1 and SH2 modes of the excited SH guided waves as research objects to obtain dispersion curves of the guided waves of different modes;
the normalized energy distribution calculation module is used for calculating normalized energy distribution of the guided waves of different modes along the thickness direction of the steel rail sample based on the dispersion curves of the guided waves of different modes;
the buried depth-energy correspondence determining module is used for integrating normalized energy distribution of the guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain correspondence of reflected guided wave energy of the defect under different normal deviations;
the normalized E-s curve generation module is used for obtaining normalized E-s curves of all mode guided waves according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations after the defect depth and the thickness of the sample are determined;
G roc an s curve graph generating module for calculating the position of the equal energy point and the guided wave ratio order coefficient G of the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot;
normal offset determination module for comparing G roc -s-plot determining normal offset of buried defect.
In still another aspect, the present invention further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and capable of running on the processor, where the processor implements the method for quantifying the depth of the rail web embedded defect when executing the computer program.
Optionally, the memory is a non-transitory computer readable storage medium.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
aiming at the problem that normal offset of an ultrasonic guided wave rail web embedded defect is difficult to obtain, the invention converts a problem of solving the normal offset of the defect into a problem of measuring energy of guided waves of different orders by utilizing the wave structure characteristic of a mixed high-order SH guided wave normal and the fusion characteristic of the SH guided waves of different orders, and firstly takes SH0, SH1 and SH2 modes of the excited SH guided wave as research objects to obtain dispersion curves of the guided waves of different modes; then calculate the displacement of different guided wave ordersThe field and energy field normalization distribution condition is used for obtaining the corresponding relation of reflected guided wave energy of defects under different normal deviations, and further obtaining normalized E-s curves of guided waves of all modes; then calculating the specific order coefficient G of the position of the equal energy point and the guided waves of different modes roc Relationship between them, control G roc The s-plot allows the determination of the normal offset s of the buried defect. The method can be used as an important supplement of ultrasonic guided wave rail defect quantification technology, can realize depth quantification and high-precision evaluation of normal deviation of the buried defect under the condition of no defect baseline signal, and is particularly suitable for detecting the buried defect of the rail network.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for quantifying the depth of a rail web embedded defect of a rail in accordance with the present invention;
FIG. 2 is a graph showing normalized E-s curves of guided waves of various modes according to an embodiment of the present invention;
FIG. 3 is a diagram of an embodiment G of the present invention roc -s-curve schematic.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Most of the existing detection technologies are sensitive to rail head and rail bottom defects, and less research is conducted on detection and quantitative characterization of rail web internal defects, so that the problems of accurate positioning and accurate quantification of rail web buried defects of the steel rail are key technical problems to be solved by the invention. The invention aims to provide a method, a system and equipment for quantifying the buried depth of a rail web defect of a steel rail, so as to realize high-precision quantification and high-sensitivity magneto-acoustic guided wave detection of the buried web defect under the condition of no defect baseline signals.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
FIG. 1 is a flow chart of a method for quantifying the depth of a rail web embedded defect in a rail in accordance with the present invention. Referring to fig. 1, the method for quantifying the burial depth of the burial defect of the rail web of the steel rail comprises the following steps:
step 1: taking SH0, SH1 and SH2 modes of the excited SH guided waves as research objects, and obtaining dispersion curves of the guided waves of different modes.
Guided wave detection is a non-destructive detection technique for identifying and locating defects or changes in a material by injecting transmitted acoustic, electromagnetic or ultrasonic energy into the material based on the propagation characteristics of the guided wave, and then measuring reflected signals caused by the defects or material changes to identify the problem. Guided wave detection is often used to identify defects such as corrosion, cracking, loosening, etc. in pipes, plates, concrete structures, etc. to aid in early discovery and preventive maintenance.
According to the mixed high-order SH-EMAT (Shear Horizontal Electromagnetic Acoustic Transducer) guided wave detection method suitable for detecting the buried defects of the rail network, firstly, displacement fields of symmetrical and antisymmetric modes are calculated according to the excited SH mode ultrasonic guided wave AISI 4340 alloy steel rail material parameters, and a dispersion curve of guided waves of different orders is obtained. Wherein the AISI 4340 alloy steel is a heat-treatable low alloy steel containing chromium, nickel and molybdenum, and has high toughness and strength in a heat-treated state.
The calculation method of the displacement field is to solve a Navier motion displacement equation (1) in an isotropic medium, consider that SH guided waves propagate along the x-axis direction and only have displacement components in the y-direction, simplify the equation (1), combine the real part of the generalized solution of the simplified equation (4) with the SH guided wave modal characteristics, and obtain the displacement fields of symmetrical and antisymmetric modes.
Wherein the Navier motion displacement equation in the isotropic medium is:
wherein λ 'and μ' are Lame constants; u is the displacement field of the particle; ρ is the medium density; let be the vector operator; t is t time Time is indicated.
According to the characteristics of SH mode, the displacement component forms in different directions are as follows:
u x ＝u z ＝0 (2)
where k=ω/c p Is wave number, ω is angular frequency, c p Is the phase velocity. u (u) x 、u y 、u z The displacement components in the x, y and z axis directions respectively. f (z) is the displacement amplitude component in the z direction.
Considering that the SH guided wave propagates along the x-axis direction and there is only a displacement component in the y-direction, equation (1) can be simplified as:
wherein the transverse wave velocity c T =μ/ρ. Combining the real part of the solution of the simplified equation (4) with the SH guided wave mode characteristics, the displacement fields of the symmetric and antisymmetric modes can be obtained:
wherein the method comprises the steps ofAnd->Displacement fields of a symmetrical mode and an antisymmetric mode respectively; A. b is a coefficient; n is a positive integer; t represents the thickness of a steel rail sample; z represents the coordinates of the sample in the thickness direction; k represents the wave number.
And then according to the displacement field equations (5) and (6) of the SH wave symmetrical mode and the anti-symmetrical mode and the boundary condition of the free surface of the free boundary steel plate, the dispersion equation of the SH wave of the symmetrical mode and the anti-symmetrical mode can be obtained. Solving the dispersion equation, and expressing the wave speed of the guided wave as a function of the product of the frequency and the thickness, so that the dispersion curves of the guided waves with different orders can be drawn. The SH0, SH1 and SH2 mode guided waves studied by the invention refer to guided waves with different orders. The dispersion curve shows the excitation frequency versus sample thickness versus guided wave order. Only if a dispersion curve is obtained, the magnitude of the excitation frequency can be determined when specific guided wave modes (such as SH0, SH1, SH 2) are studied. For example, the excitation frequency is below the SH1 cut-off frequency, and the SH2 mode cannot be excited. Therefore, the obtained dispersion curve of the guided waves with different orders is the premise of exciting the SH0, SH1 and SH2 guided waves subsequently, and is also an important theoretical basis of the SH guided wave detection technology.
Step 2: based on the dispersion curves of the guided waves of different modes, the normalized energy distribution of the guided waves of different modes is calculated along the thickness direction of the steel rail sample.
The SH0, SH1, SH2 mode guided waves refer to guided waves of different orders, and vibration modes of the guided waves of different orders are different. According to the invention, SH0, SH1 and SH2 modes are taken as research objects, displacement fields and energy field normalized distribution of guided waves of different modes are calculated along the thickness z direction, wherein the displacement fields are represented as u, and the energy fields are represented as u 2 。
The displacement field formula for different modes along the thickness z direction can be expressed as:
wherein the method comprises the steps ofAnd->Respectively representing displacement fields of three modal guided waves of SH0, SH1 and SH2 along the thickness direction of the steel rail sample; a 'and B' are constant coefficients; t represents the thickness of the sample; z represents the coordinates of the sample in the thickness direction; y represents the circumferential propagation component of the ultrasonic wave.
And calculating the normalized distribution of the energy field (square of the displacement field) according to the displacement fields of the guided waves of different modes, so as to obtain the normalized energy distribution of the guided waves of different modes.
Step 3: and integrating the normalized energy distribution of the guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain the corresponding relation of the reflected guided wave energy of the defect under different normal deviations.
The correspondence of reflected guided wave energy for different normal deviations of the defect refers to the relation of guided wave energy E to normal deviation s. The normal offset s is the normal distance between the three-dimensional geometric center of the defect and the thickness center of the rail web, namely the burial depth of the defect. Since the guided wave energy reflected by the defect is related to the defect depth and the normal shift, and the defect depth can be calculated by combining SH0 mode guided wave with a virtual time reversal method, the corresponding relation of the reflected guided wave energy of the defect under different normal shifts satisfies the following formula:
wherein E is SH0 、E SH1 And E is SH2 The guided wave energy of three modal guided waves of SH0, SH1 and SH2 are respectively represented; t is the thickness of the sample; s is the normal offset of the defect; d is the defect depth.
Step 4: and after the depth of the defect and the thickness of the sample are determined, obtaining a normalized E-s curve of each mode guided wave according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations.
When the defect depth d and the specimen thickness t are determined, the energy E is a function of the normal shift s of the defect. Wherein the defect depth d and the specimen thickness t can be measured by a conventional ultrasonic bulk wave detection method. The normalized E-s curve is drawn according to the E-s function (8), the segmentation is carried out, the upper bound of the segmentation function is obtained, and the maximum value is introduced to normalize the image, namely, the maximum value is dimensionless 1. The normalized E-s curves of the SH0, SH1 and SH2 mode guided waves are shown in FIG. 2, the abscissa is the normal deviation s, and the ordinate is the guided wave energy E, including E SH0 、E SH1 And E is SH2 。
Step 5: calculating the position of an equal energy point and the guided wave ratio order coefficient G of the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot.
As shown in FIG. 2, the intersection of normalized E-s curves of SH1 and SH2 mode guided waves, i.e., E, is determined SH2 ＝E SH1 The normal offset corresponding to the time is equal energy point s c Is a position of (c).
When E is SH2 ＝E SH1 At the time, the equal energy point s is calculated c The guided wave ratio order coefficient G of the position of the guided wave and the guided wave of different modes roc Is the relation of:
wherein the method comprises the steps ofG representing second order guided wave roc G of value and first order guided wave roc A ratio of values; />G representing first order guided waves roc G of value and zero order guided wave roc Ratio of values./>At s epsilon [0,0.5t]When being a monotonically increasing function, when s > s c The relationship is satisfied within the range of (3). About->When E is SH2 ＝E SH1 When having physical meaning s c Take the value of
Then taking the normal offset s as the abscissa, and taking the guided wave ratio order coefficient G of the guided waves of different modes roc (includeAnd) As the ordinate, G is generated roc S-plot, as shown in fig. 3. It can be found that->At s is less than or equal to s c Is a monotonic function in the range of (a), i.e. for a certain thickness t of the sample with a known defect depth d, by calculating the iso-energy point s c And measuring the relative reflected energy ratio G of the guided waves of different modes roc The normal offset s of the buried defect can be uniquely determined. It should be noted that since s.ltoreq.s c When E is SH2 Always not less than E SH1 Thus->In addition, in the case of s > s c Within all s ranges, E SH1 Is always less than E SH0 Thus->It is possible to determine which G to use by this method roc (/>Or->)。
Step 6: control G roc -s-plot determining normal offset of buried defect.
G shown in FIG. 3 roc In the s graph, G roc The vertical axis value is known, and the horizontal axis value, namely the normal offset s, can be obtained by comparing the graph. As can be seen from the view of figure 3,and->Corresponding to different values of s, the values are segmented on the horizontal axis, and when s is less than or equal to s c In the case of taking->Corresponding normal offset s, when s > s c In the case of taking->A corresponding normal offset s.
Therefore, aiming at the problems that the buried defect of the rail web of the ultrasonic guided wave rail is difficult to measure and the normal offset of the defect is difficult to obtain, the invention can quickly and accurately determine the normal offset s of the buried defect by utilizing the wave structure characteristic of the mixed high-order SH guided wave normal.
In order to facilitate better understanding of the present invention, a method for quantifying the depth of a rail web embedded defect according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
In this embodiment, the axial distance a of the buried defect is 600mm, the circumferential distance c is 0mm, and the length l and width w of the defect are both 2mm. In the course of grindingS is a relative order coefficient G of guided wave roc In the relation between them, the defect depth d was fixed to 2mm.
Fig. 2 shows experimentally measured reflected wave signals at different defect normal shifts s. It can be seen that as s increases, the amplitude of the SH0 guided wave signal remains unchanged, the amplitude of the SH1 guided wave increases, and the amplitude of the SH2 guided wave decreases first and then, which is caused by the different distribution characteristics of the different guided wave modes. FIG. 3 showsAnd->And the relation between the S and the S adopts the results of analysis, simulation and experimental methods to compare and mutually verify the conditions. It should be noted that s c =1.73 mm is the iso-energy point under the conditions of this example. Due to->And->The normal shift s of the buried defect can thus be uniquely determined. The theoretical calculation, simulation analysis and experimental measurement results shown in fig. 3 mutually verify that the parameter fitness is greater than 98.5%, and prove the effectiveness of the method for quantifying the buried defect of the rail web of the steel rail in the mixed high-order guided wave detection.
Based on the method provided by the invention, the invention also provides a system for quantifying the burial depth of the burial defect of the rail web of the steel rail, which comprises the following steps:
the dispersion curve drawing module is used for taking SH0, SH1 and SH2 modes of the excited SH guided waves as research objects to obtain dispersion curves of the guided waves of different modes;
the normalized energy distribution calculation module is used for calculating normalized energy distribution of the guided waves of different modes along the thickness direction of the steel rail sample based on the dispersion curves of the guided waves of different modes;
the buried depth-energy correspondence determining module is used for integrating normalized energy distribution of the guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain correspondence of reflected guided wave energy of the defect under different normal deviations;
the normalized E-s curve generation module is used for obtaining normalized E-s curves of all mode guided waves according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations after the defect depth and the thickness of the sample are determined;
G roc an s curve graph generating module for calculating the position of the equal energy point and the guided wave ratio order coefficient G of the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot;
normal offset determination module for comparing G roc -s-plot determining normal offset of buried defect.
Further, the present invention also provides an electronic device, which may include: a processor, a communication interface, a memory, and a communication bus. The processor, the communication interface and the memory complete communication with each other through a communication bus. The processor may call a computer program in memory to perform the rail web defect burial depth quantification method.
Furthermore, the computer program in the above-described memory may be stored in a non-transitory computer readable storage medium when it is implemented in the form of a software functional unit and sold or used as a separate product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a U disk, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk.
The invention provides a high-sensitivity buried defect buried depth quantification method based on a guided wave ratio order coefficient by utilizing the normal wave structural characteristics of mixed high-order SH guided waves, which is beneficial to the fusion characteristic of the SH guided waves of different orders and converts the problem of solving the normal displacement of the defect into the problem of measuring the energy of the guided waves of different orders. In addition, for a test piece with a certain thickness and known defect depth, the normal displacement of the buried defect can be uniquely and quantitatively determined by calculating the positions of the equal energy points and measuring the specific order coefficients of different guided wave modes, the depth quantization and high-precision evaluation of the normal displacement of the buried defect can be realized under the condition of no-defect baseline signals, and the method has a wide application prospect.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (9)
1. A method for quantifying the burial depth of a rail web burial defect of a steel rail is characterized by comprising the following steps:
taking SH0, SH1 and SH2 modes of the excited SH guided waves as research objects, and obtaining dispersion curves of the guided waves of different modes;
calculating normalized energy distribution of the guided waves of different modes along the thickness direction of the steel rail sample based on the dispersion curves of the guided waves of different modes;
integrating normalized energy distribution of guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain the corresponding relation of reflected guided wave energy of the defect under different normal deviations;
after the depth of the defect and the thickness of the sample are determined, a normalized E-s curve of each mode guided wave is obtained according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations;
calculating the position of an equal energy point and the guided wave ratio order coefficient G of the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot;
control G roc -s-plot determining normal offset of buried defect.
2. The method for quantifying the burial depth of a rail web burial defect of a steel rail according to claim 1, wherein the obtaining the dispersion curve of the guided waves of different modes by taking the SH0, SH1 and SH2 modes of the excited SH guided waves as the study object specifically comprises:
simplifying a Navier motion displacement equation according to the displacement characteristic of the excited SH guided wave to obtain a simplified equation;
combining the real part of the simplified equation general solution with SH guided wave mode characteristics to obtain displacement field equations of symmetrical and antisymmetric modes;
according to displacement field equations of symmetrical and antisymmetric modes and free surface boundary conditions of the free boundary steel plate, obtaining dispersion equations of SH guided waves of the symmetrical and antisymmetric modes;
solving the dispersion equation, expressing the guided wave speed as a function of the frequency-thickness product, and drawing dispersion curves of three modal guided waves of SH0, SH1 and SH 2.
3. The method for quantifying the burial depth of the rail web burial defect of the steel rail according to claim 2, wherein the calculating the normalized energy distribution of the guided waves of different modes along the thickness direction of the steel rail sample based on the dispersion curves of the guided waves of different modes specifically comprises:
based on the dispersion curves of the guided waves of different modes, a formula is adoptedGauge along thickness direction of steel rail sampleCalculating displacement fields of the guided waves of different modes; wherein-> And->Respectively representing displacement fields of three modal guided waves of SH0, SH1 and SH2 along the thickness direction of the steel rail sample; a 'and B' are constant coefficients; t represents the thickness of the sample; z represents the coordinates of the sample in the thickness direction;
and calculating the normalized distribution of the energy field according to the displacement fields of the guided waves of different modes, so as to obtain the normalized energy distribution of the guided waves of different modes.
4. The method for quantifying the burial depth of a rail web embedded defect of a steel rail according to claim 3, wherein integrating the normalized energy distribution of the guided waves of different modes along the upper and lower boundaries of the depth direction of the defect to obtain the corresponding relation of the reflected guided wave energy of the defect under different normal deviations specifically comprises:
according to the formulaIntegrating normalized energy distribution of guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain the corresponding relation of reflected guided wave energy of the defect under different normal deviations; wherein E is SH0 、E SH1 And E is SH2 The guided wave energy of three modal guided waves of SH0, SH1 and SH2 are respectively represented; s is the normal offset of the defect; d is the defect depth.
5. The method for quantifying the burial depth of a rail web embedded defect of a steel rail according to claim 4, wherein after the depth of the defect and the thickness of the sample are determined, a normalized E-s curve of each mode guided wave is obtained according to the correspondence of the reflected guided wave energy of the defect under different normal deviations, and the method specifically comprises:
aiming at the determined defect depth d and sample thickness t of the steel rail sample, drawing normalized E-s curves of three mode guided waves of SH0, SH1 and SH2 in a segmented manner according to the corresponding relation of reflected guided wave energy of the defect under different normal deviations; the abscissa of the normalized E-s curve is normal offset, and the ordinate is guided wave energy.
6. The method for quantifying the burial depth of a rail web burial defect of a steel rail according to claim 5, wherein the step coefficient G of the position of the equal energy point and the guided wave of different modes is calculated according to the normalized E-s curve of the guided wave of each mode roc Generates G roc -s-plot, comprising in particular:
calculating E according to normalized E-s curves of SH1 and SH2 mode guided waves SH2 ＝E SH1 Time-constant energy point s c Is a position of (2);
using the formula
Calculating the guided wave specific order coefficient G of the guided waves of different modes roc The method comprises the steps of carrying out a first treatment on the surface of the Wherein the method comprises the steps ofG representing second order guided wave roc G of value and first order guided wave roc A ratio of values; />G representing first order guided waves roc G of value and zero order guided wave roc A ratio of values;
taking the normal offset s as the abscissa, and taking the corresponding guided wave ratio order coefficientOr->As the ordinate, G is generated roc -s-plot.
7. A rail web defect burial depth quantization system, comprising:
the dispersion curve drawing module is used for taking SH0, SH1 and SH2 modes of the excited SH guided waves as research objects to obtain dispersion curves of the guided waves of different modes;
the normalized energy distribution calculation module is used for calculating normalized energy distribution of the guided waves of different modes along the thickness direction of the steel rail sample based on the dispersion curves of the guided waves of different modes;
the buried depth-energy correspondence determining module is used for integrating normalized energy distribution of the guided waves of different modes along the upper boundary and the lower boundary of the depth direction of the defect to obtain correspondence of reflected guided wave energy of the defect under different normal deviations;
the normalized E-s curve generation module is used for obtaining normalized E-s curves of all mode guided waves according to the corresponding relation of the reflected guided wave energy of the defect under different normal deviations after the defect depth and the thickness of the sample are determined;
G roc an s curve graph generating module for calculating the position of the equal energy point and the guided wave ratio order coefficient G of the guided waves of different modes according to the normalized E-s curve of the guided waves of each mode roc Generates G roc -s-plot;
normal offset determination module for comparing G roc -s-plot determining normal offset of buried defect.
8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the rail web defect burial depth quantification method of any one of claims 1-6 when the computer program is executed by the processor.
9. The electronic device of claim 8, wherein the memory is a non-transitory computer readable storage medium.
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| CN117871693B (en) * | 2024-03-11 | 2024-05-17 | 西南交通大学 | Method and device for exciting zero-order horizontal shear wave in steel rail |
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