A steel rail stress measurement system based on electromagnetic ultrasonic transverse waves

Abstract

The application discloses a steel rail stress measurement system based on electromagnetic ultrasonic orthogonal transverse waves, which comprises an electromagnetic ultrasonic probe and a signal processing unit. The electromagnetic ultrasonic probe is configured as an orthogonal coil group with an axis, and the electromagnetic ultrasonic probe generates eddy current under the excitation of alternating current and simultaneously generates first transverse waves and second transverse waves in the steel rail. The propagation directions of the first transverse waves and the second transverse waves are both vertically downward from the center of the rail head of the steel rail. The vibration direction of the first transverse waves is the length direction of the steel rail, and the vibration direction of the second transverse waves is the width direction of the rail head of the steel rail. The vibration directions of the first transverse waves and the second transverse waves are perpendicular to each other to form an orthogonal relationship. The signal processing unit is used for synchronously receiving echo signals of the first transverse waves and the second transverse waves, calculating the propagation time difference between the first transverse waves in the length vibration direction and the second transverse waves in the width vibration direction, and evaluating the axial stress of the steel rail according to the propagation time difference between the first transverse waves and the second transverse waves.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology for rails, and in particular to a rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves. Background Technology

[0002] Under the influence of train loads and temperature changes, steel rails experience complex stress states. Abnormal stress accumulation can lead to fatigue damage or even fracture of the rails, seriously affecting train operation safety. Therefore, accurate and efficient measurement of rail stress is of great significance.

[0003] Based on the ultrasonic propagation characteristics of materials, the speed of ultrasonic wave propagation differs when tensile or compressive stress is present, and the direction of stress is related to the direction of ultrasonic vibration. When the direction of stress is consistent with the direction of ultrasonic vibration, the change in sound velocity has a certain proportional relationship with the change in stress. Therefore, the presence of stress in a material can be determined by measuring the difference in transverse wave sound velocity in different directions.

[0004] Existing methods for measuring rail stress mainly include strain gauge method, X-ray method, and electromagnetic ultrasonic method. Among them, electromagnetic ultrasonic method has become a research hotspot due to its advantages such as non-contact, no need for coupling agent, and online measurement capability. Traditional electromagnetic ultrasonic stress measurement systems typically use a single-direction shear wave for measurement, requiring multiple adjustments of the probe direction to obtain stress information in different directions, resulting in complex operation and low efficiency. In addition, some systems use multiple probes to achieve multi-directional measurement, leading to complex system structure, increased cost, and difficulty in adapting to the measurement needs of different locations on the rail (such as the rail head tread and side). Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves. This rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves has a simple structure, high measurement efficiency, and can adapt to different rail head positions.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves includes an electromagnetic ultrasonic probe and a signal processing unit. The signal output terminal of the electromagnetic ultrasonic probe is electrically connected to the corresponding signal input terminal of the signal processing unit. The electromagnetic ultrasonic probe is configured as an orthogonal coil group with orthogonal axes. Under the excitation of alternating current, the electromagnetic ultrasonic probe generates eddy currents and simultaneously generates a first shear wave and a second shear wave on the rail. The propagation directions of both the first and second shear waves are perpendicular to the center of the rail head and downwards. The vibration direction of the first shear wave is along the length of the rail, and the vibration direction of the second shear wave is along the width of the rail head. The vibration directions of the first and second shear waves are perpendicular to each other and form an orthogonal relationship. The signal processing unit is used to synchronously receive the echo signals of the first and second shear waves, calculate the propagation time difference between the first shear wave in the length vibration direction and the second shear wave in the width vibration direction, and evaluate the axial stress of the rail based on the propagation time difference between the first and second shear waves.

[0008] For rail inspection, rail stress primarily occurs along the length of the rail. Therefore, the stress state can be determined by measuring the velocity of the first shear wave vibrating along the rail's length and the velocity of the second shear wave vibrating along the width of the rail head. When the rail height is constant, the difference between the velocity of the first shear wave along the length and the velocity of the second shear wave along the width can be directly represented by measuring the difference between the propagation times of the first and second shear waves along the length and width. During measurement, the electromagnetic ultrasonic probe can be placed at the center of the tread or the side of the rail head. By adjusting the angle of the probe, the vibration directions of the two sets of orthogonal shear waves are precisely aligned with the length and width directions of the rail, respectively, adapting to the needs of different measurement positions.

[0009] The above-mentioned electromagnetic ultrasonic probe synchronously excites two sets of orthogonal transverse waves: the propagation direction of the first transverse wave is the same as that of the second transverse wave, and the vibration direction of the first transverse wave is perpendicular to the vibration direction of the second transverse wave, forming an orthogonal relationship. The data required for stress assessment can be obtained in one measurement without repeatedly adjusting the direction of the electromagnetic ultrasonic probe. Compared with the traditional single-direction measurement system, the measurement efficiency is improved.

[0010] In a preferred embodiment, the electromagnetic ultrasonic probe includes a probe housing, a magnet, a sound-insulating layer, and an orthogonal coil group. The orthogonal coil group includes a first electromagnetic coil and a second electromagnetic coil, which are stacked vertically inside the probe housing. The magnet is installed inside the probe housing above the first electromagnetic coil, and the sound-insulating layer is positioned between the magnet and the first electromagnetic coil. The axis of the first electromagnetic coil is parallel to the length of the rail, and the eddy currents generated after energization are distributed along the width of the rail head, thereby exciting a first transverse wave with the vibration direction along the length of the rail. The axis of the second electromagnetic coil is perpendicular to the length of the rail, and the eddy currents generated after energization are distributed along the length of the rail, thereby exciting a second transverse wave with the vibration direction along the width of the rail head. The first and second electromagnetic coils generate eddy currents under alternating current excitation, thereby exciting the first and second transverse waves in orthogonal directions. Typically, the first and second electromagnetic coils are manufactured using PCB circuit printing technology, and the ultrasonic frequency is determined according to the excitation frequency.

[0011] In a further preferred embodiment, the first electromagnetic coil is a serrated conductor extending axially along the length of the rail; the second electromagnetic coil is a serrated conductor with its axial direction perpendicular to the length of the rail. The serrated conductor winding method results in a periodic gradient distribution of the alternating magnetic field generated by the coil. Compared to traditional rectangular coils, this increases the magnetic field strength, leading to a higher and more concentrated eddy current density induced on the rail surface. The serrated conductor of the first electromagnetic coil (axially along the length of the rail) ensures that the eddy currents are strictly distributed along the width of the rail, preventing eddy current diffusion and ensuring that the direction of the excited first transverse wave vibration is only along the length of the rail. The serrated conductor of the second electromagnetic coil (axially perpendicular to the length of the rail) also ensures that the eddy currents are strictly distributed along the length of the rail, ensuring that the direction of the second transverse wave vibration is only along the width of the rail. When stacked vertically, the eddy current directions of the two sets of coils do not intersect.

[0012] In a further preferred embodiment, the electromagnetic ultrasound probe further includes a probe cover, a probe wire clamp, a probe wire, a lead wire, and a protective sheet. The probe housing is cylindrical, with the probe cover mounted on top and covering the upper opening of the probe housing. The probe cover has a wire outlet, and the probe wire clamp is fixed at the outlet to secure the probe wire. The lead wire is located inside the probe housing, with one end soldered to the electrodes of the first and second electromagnetic coils, and the other end extending to the outlet and connecting to the probe wire. The protective sheet is mounted at the lower end of the probe housing and covers the lower opening, with the second electromagnetic coil positioned above the protective sheet. The lead wire connects the first and second electromagnetic coils to external signal processing equipment to achieve signal transmission.

[0013] In a further preferred embodiment, the magnet is a permanent magnet. The permanent magnet is made of neodymium iron boron material, providing a uniform static magnetic field.

[0014] In a further preferred embodiment, the signal processing unit includes an excitation module, a receiving module, and a data processing module. The excitation module provides a high-frequency alternating current to the first and second electromagnetic coils, with a frequency range of 1-10MHz, generating an alternating magnetic field that induces eddy currents on the rail surface. The eddy currents are subjected to Lorentz force in the static magnetic field, causing the internal medium of the rail to vibrate elastically, forming orthogonal first and second transverse waves that propagate vertically downwards from the center of the rail head. The receiving module receives the transverse wave echo signals induced by the first and second electromagnetic coils, amplifies, filters, and performs analog-to-digital conversion before transmitting them to the data processing module. The data processing module uses a cross-correlation algorithm to calculate the propagation time difference between the first and second transverse waves.

[0015] The excitation module described above can excite the first electromagnetic coil and the second electromagnetic coil simultaneously, or excite the first electromagnetic coil and the second electromagnetic coil in a time-division manner to avoid interference. The receiving module can receive the echo signals of the orthogonal first transverse wave and the second transverse wave synchronously or in a time-division manner.

[0016] In a further optimized scheme, the specific steps of the cross-correlation algorithm are as follows:

[0017] (1) Perform noise reduction and filtering preprocessing operations on the received first shear wave echo signal and second shear wave echo signal;

[0018] (2) Calculate the cross-correlation function of the first shear wave echo signal and the second shear wave echo signal, find the peak position of the cross-correlation function, and determine the propagation time difference Δt;

[0019] (3) The axial stress σ of the rail is calculated according to the formula σ=K·Δt, where K is the stress coefficient and is determined by calibration experiment.

[0020] In a preferred embodiment, the rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves further includes a display unit, and the signal output terminal of the signal processing unit is electrically connected to the signal input terminal of the display unit. The display unit can then display the measurement results of the axial stress of the rail.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) Compared with the traditional single-direction transverse wave measurement, which requires multiple adjustments of the probe direction to obtain multi-dimensional stress information, the present invention uses the same electromagnetic ultrasonic probe to synchronously excite the orthogonal first transverse wave and second transverse wave, and can obtain the complete signal required for stress assessment in one measurement. There is no need to repeatedly adjust the position of the electromagnetic ultrasonic probe, which shortens the measurement time and simplifies the operation process.

[0023] (2) Compared with multi-probe multi-directional measurement systems, the present invention only requires one electromagnetic ultrasonic probe to realize orthogonal transverse wave excitation and signal reception. There is no need to add additional probes, switching mechanisms and complex synchronization control modules. The structure is simple, reducing cost and maintenance difficulty.

[0024] (3) The electromagnetic ultrasonic probe of the present invention is compact in design and only needs to be attached to the center of the tread or the center of the side of the rail head during measurement. No special tooling is required: tread measurement can meet the needs of conventional line inspection, and side measurement can be adapted to scenarios where the rail head tread is severely worn or covered with oil. There is no need to replace the probe or adjust the system parameters. It is compatible with the measurement needs of different positions of the rail, improves versatility, and solves the pain point of poor adaptability of single probe in traditional systems. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an embodiment of the present invention, showing the electromagnetic ultrasonic probe being attached to the center of the rail head tread.

[0026] Figure 2 yes Figure 1 The left view;

[0027] Figure 3 This is a schematic diagram of an embodiment of the present invention, showing the electromagnetic ultrasonic probe attached to the center position of the side of the rail head;

[0028] Figure 4 This is a data flow diagram of an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of an electromagnetic ultrasonic probe according to an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the first electromagnetic coil according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the second electromagnetic coil according to an embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram of the first electromagnetic coil and the second electromagnetic coil stacked one on top of the other on the rail head tread surface according to an embodiment of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1-8As shown, the rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves in this embodiment includes an electromagnetic ultrasonic probe 1 and a signal processing unit 2. The signal output terminal of the electromagnetic ultrasonic probe 1 is electrically connected to the corresponding signal input terminal of the signal processing unit 2. The electromagnetic ultrasonic probe 1 is configured as an orthogonal coil group 14 with orthogonal axes. Under the excitation of alternating current, the electromagnetic ultrasonic probe 1 generates eddy currents and simultaneously generates a first shear wave and a second shear wave on the rail 4. The propagation directions of the first and second shear waves are both vertically downward from the center of the rail head of the rail 4. The vibration direction of the first shear wave is the length direction of the rail 4, and the vibration direction of the second shear wave is the width direction of the rail head 41. The vibration directions of the first and second shear waves are perpendicular to each other and form an orthogonal relationship. The signal processing unit 2 is used to synchronously receive the echo signals of the first and second shear waves, calculate the propagation time difference between the first shear wave in the length vibration direction and the second shear wave in the width vibration direction, and evaluate the axial stress of the rail 4 based on the propagation time difference between the first and second shear waves.

[0035] For the inspection of rail 4, the rail stress is mainly along the length direction of rail 4. Therefore, the stress state of rail 4 can be determined by measuring the sound velocity of the first transverse wave vibrating along the length direction of rail 4 and the sound velocity of the second transverse wave vibrating along the width direction of rail head 41. When the height of rail 4 is constant, the difference between the sound velocity of the first transverse wave in the length vibration direction and the sound velocity of the second transverse wave in the width vibration direction can be directly represented by measuring the difference between the propagation time of the first transverse wave in the length vibration direction and the propagation time of the second transverse wave in the width vibration direction. During measurement, the electromagnetic ultrasonic probe 1 can be placed at the center of the tread surface or the center of the side of rail head 41. By adjusting the angle of the electromagnetic ultrasonic probe 1, it can be ensured that the vibration directions of the two sets of orthogonal transverse waves are precisely aligned with the length and width directions of rail 4, respectively, to adapt to the usage requirements of different measurement positions.

[0036] The same electromagnetic ultrasonic probe 1 synchronously excites two sets of orthogonal transverse waves: the propagation direction of the first transverse wave is the same as that of the second transverse wave, and the vibration direction of the first transverse wave is perpendicular to the vibration direction of the second transverse wave, forming an orthogonal relationship. The data required for stress assessment can be obtained in one measurement without repeatedly adjusting the direction of the electromagnetic ultrasonic probe 1. Compared with the traditional single-direction measurement system, the measurement efficiency is improved.

[0037] This embodiment also includes a display unit 3, and the signal output terminal of the signal processing unit 2 is electrically connected to the signal input terminal of the display unit 3. The display unit 3 can display the measurement results of the axial stress of the rail 4.

[0038] The electromagnetic ultrasonic probe 1 includes a probe housing 11, a magnet 12, a sound insulation layer 13, and the orthogonal coil group 14. The orthogonal coil group 14 includes a first electromagnetic coil 141 and a second electromagnetic coil 142. The first electromagnetic coil 141 and the second electromagnetic coil 142 are stacked vertically inside the probe housing 11. The magnet 12 is installed inside the probe housing 11 and above the first electromagnetic coil 141. The sound insulation layer 13 is disposed between the magnet 12 and the first electromagnetic coil 141. The axial direction of the first electromagnetic coil 141 is parallel to the length direction of the rail 4. After being energized, the eddy current generated is distributed along the width direction of the rail head 41, thereby exciting a first transverse wave with the vibration direction in the length direction of the rail 4. The axial direction of the second electromagnetic coil 142 is perpendicular to the length direction of the rail 4. After being energized, the eddy current generated is distributed along the length direction of the rail 4, thereby exciting a second transverse wave with the vibration direction in the width direction of the rail head 41. The first electromagnetic coil 141 and the second electromagnetic coil 142 generate eddy currents under alternating current excitation, which in turn excite a first transverse wave and a second transverse wave in orthogonal directions. Typically, the first electromagnetic coil 141 and the second electromagnetic coil 142 are manufactured using PCB circuit printing technology, and the ultrasonic frequency is determined according to the excitation frequency.

[0039] The first electromagnetic coil 141 is a serrated conductor extending axially along the length of the rail; the second electromagnetic coil 142 is a serrated conductor with its axial direction perpendicular to the length of the rail. The serrated winding method creates a periodic gradient distribution of the alternating magnetic field generated by the coil, which, compared to traditional rectangular coils, increases the magnetic field strength, resulting in a higher and more concentrated eddy current density induced on the rail surface. The serrated conductor of the first electromagnetic coil 141 (axially along the length of the rail) ensures that the eddy currents are strictly distributed along the width of the rail, preventing eddy current diffusion and ensuring that the direction of the excited first transverse wave vibration is only along the length of the rail. The serrated conductor of the second electromagnetic coil 142 (axially perpendicular to the length of the rail) also ensures that the eddy currents are strictly distributed along the length of the rail, ensuring that the direction of the second transverse wave vibration is only along the width of the rail. When stacked vertically, the eddy current directions of the two sets of coils do not cross or interfere with each other.

[0040] The electromagnetic ultrasound probe 1 also includes a probe cover 15, a probe wire clamp 16, a probe wire 17, a lead wire 18, and a protective plate 19. The probe housing 11 is cylindrical. The probe cover 15 is installed on the top of the probe housing 11 and covers the upper opening of the probe housing 11. The probe cover 15 has a wire outlet 151. The probe wire clamp 16 is fixed at the wire outlet 151 and fixes the probe wire 17. The lead wire 18 is disposed inside the probe housing 11, and one end of the lead wire 18 is respectively soldered to the electrodes of the first electromagnetic coil 141 and the second electromagnetic coil 142. The other end of the lead wire 18 extends to the wire outlet 151 and connects to the probe wire 17. The protective plate 19 is installed at the lower end of the probe housing 11 and covers the lower opening of the probe housing 11. The second electromagnetic coil 142 is located above the protective plate 19. The lead wire 18 connects the first electromagnetic coil 141 and the second electromagnetic coil 142 to external signal processing equipment to realize signal transmission.

[0041] Magnet 12 is a permanent magnet. The permanent magnet is made of neodymium iron boron material, which provides a uniform static magnetic field.

[0042] The signal processing unit 2 includes an excitation module, a receiving module, and a data processing module. The excitation module provides a high-frequency alternating current to the first electromagnetic coil 141 and the second electromagnetic coil 142, with a frequency range of 1-10MHz, generating an alternating magnetic field that induces eddy currents on the rail surface. The eddy currents are subjected to Lorentz force in the static magnetic field, causing the internal medium of the rail to vibrate elastically, forming orthogonal first and second transverse waves that propagate vertically downwards from the center of the rail head. The receiving module receives the transverse wave echo signals induced by the first electromagnetic coil 141 and the second electromagnetic coil 142, amplifies, filters, and performs analog-to-digital conversion before transmitting them to the data processing module. The data processing module uses a cross-correlation algorithm to calculate the propagation time difference between the first and second transverse waves.

[0043] The excitation module described above can simultaneously excite the first electromagnetic coil 141 and the second electromagnetic coil 142, or excite the first electromagnetic coil 141 and the second electromagnetic coil 142 in a time-division manner to avoid interference. The receiving module can synchronously or in a time-division manner receive the orthogonal first transverse wave echo signal and the second transverse wave echo signal.

[0044] The specific steps of the cross-correlation algorithm are as follows:

[0045] (1) Perform noise reduction and filtering preprocessing operations on the received first shear wave echo signal and second shear wave echo signal;

[0046] (2) Calculate the cross-correlation function of the first shear wave echo signal and the second shear wave echo signal, find the peak position of the cross-correlation function, and determine the propagation time difference Δt;

[0047] (3) The axial stress σ of the rail is calculated according to the formula σ=K·Δt, where K is the stress coefficient and is determined by calibration experiment.

[0048] Furthermore, it should be noted that the names of the various parts of the specific embodiments described in this specification may differ. All equivalent or simple variations made to the structure, features, and principles described in this invention are included within the scope of protection of this invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this invention or exceed the scope defined in these claims, all of which should fall within the scope of protection of this invention.

Claims

1. A rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves, comprising an electromagnetic ultrasonic probe and a signal processing unit, wherein the signal output terminal of the electromagnetic ultrasonic probe is electrically connected to the corresponding signal input terminal of the signal processing unit; characterized in that: The electromagnetic ultrasound probe includes a probe housing, a magnet, a sound insulation layer, and an orthogonal coil group with orthogonal axes. The orthogonal coil group includes a first electromagnetic coil and a second electromagnetic coil, which are stacked vertically inside the probe housing. The magnet is installed inside the probe housing and above the first electromagnetic coil. The sound insulation layer is placed between the magnet and the first electromagnetic coil. The first electromagnetic coil is a wire that extends axially along the length of the rail and is distributed in a sawtooth pattern. The axial direction of the first electromagnetic coil is parallel to the length of the rail. When energized, the eddy current generated is distributed along the width of the rail head, thereby exciting the first transverse wave with the vibration direction along the length of the rail. The second electromagnetic coil is a wire with its axis perpendicular to the length of the rail and distributed in a sawtooth pattern. The axis of the second electromagnetic coil is perpendicular to the length of the rail. When energized, the eddy current generated is distributed along the length of the rail, thereby exciting a second transverse wave with the vibration direction in the width direction of the rail head. The propagation directions of the first and second transverse waves are both vertically downward from the center of the rail head, and the vibration directions of the first and second transverse waves are perpendicular to each other and form an orthogonal relationship. Place the electromagnetic ultrasonic probe at the center of the tread or the center of the side of the rail head. By adjusting the angle of the electromagnetic ultrasonic probe, the vibration directions of the two sets of orthogonal transverse waves are precisely aligned with the length and width directions of the rail, respectively. The signal processing unit is used to synchronously receive the echo signals of the first shear wave and the second shear wave, calculate the propagation time difference between the first shear wave in the length vibration direction and the second shear wave in the width vibration direction using a cross-correlation algorithm, and evaluate the axial stress of the rail based on the propagation time difference between the first and second shear waves.

2. The rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves as described in claim 1, characterized in that: The electromagnetic ultrasound probe also includes a probe cover, a probe wire clamp, a probe wire, a lead wire, and a protective sheet. The probe housing is cylindrical, and the probe cover is installed on the top of the probe housing and covers the upper opening of the probe housing. The probe cover has a wire outlet, and the probe wire clamp is fixed at the wire outlet to fix the probe wire. The lead wire is placed inside the probe housing, and one end of the lead wire is welded to the electrodes of the first electromagnetic coil and the second electromagnetic coil, respectively. The other end of the lead wire extends to the wire outlet and connects to the probe wire. The protective sheet is installed at the lower end of the probe housing and covers the lower opening of the probe housing. The second electromagnetic coil is located above the protective sheet.

3. The rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves as described in claim 1, characterized in that: The magnet is a permanent magnet.

4. The rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves as described in claim 1, characterized in that: The signal processing unit includes an excitation module, a receiving module, and a data processing module. The excitation module provides a high-frequency alternating current to the first and second electromagnetic coils, with a frequency range of 1-10MHz, generating an alternating magnetic field that induces eddy currents on the rail surface. The eddy currents are subjected to Lorentz force in the static magnetic field, causing the internal medium of the rail to vibrate elastically, forming orthogonal first and second transverse waves that propagate vertically downwards from the center of the rail head. The receiving module receives the transverse wave echo signals induced by the first and second electromagnetic coils, amplifies, filters, and performs analog-to-digital conversion before transmitting them to the data processing module. The data processing module uses a cross-correlation algorithm to calculate the propagation time difference between the first and second transverse waves.

5. The rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves as described in claim 4, characterized in that: The specific steps of the cross-correlation algorithm are as follows: (1) Perform noise reduction and filtering preprocessing operations on the received first shear wave echo signal and second shear wave echo signal; (2) Calculate the cross-correlation function of the first shear wave echo signal and the second shear wave echo signal, find the peak position of the cross-correlation function, and determine the propagation time difference Δt; (3) The axial stress σ of the rail is calculated according to the formula σ=K·Δt, where K is the stress coefficient and is determined by calibration experiment.

6. The rail stress measurement system based on electromagnetic ultrasonic orthogonal shear waves as described in claim 1, characterized in that: It also includes a display unit, wherein the signal output terminal of the signal processing unit is electrically connected to the signal input terminal of the display unit.

Images