Wideband Magnetostrictive SH Guided Wave Detection Device and Method

Abstract

Wideband magnetostrictive SH guided wave detection device and method, which relate to the technical field of nondestructive testing. Aiming at the problem that the existing magnetostrictive SH guided wave technology can only be applied to manual detection and it is difficult to monitor industrial plates and pipe fittings for a long time, the technical solution provided by this application is as follows: The wideband magnetostrictive SH guided wave detection device includes: an even number of permanent magnets, a magnetostrictive tape, coils and a coupling agent; the magnetostrictive tape is pasted along the circumference of the workpiece to be measured for at least one week through the coupling agent; the even number of permanent magnets are arranged in a circular manner on the magnetostrictive tape, and the magnetization directions of two adjacent permanent magnets are opposite; a coil is wound on each permanent magnet, the winding directions of the coils on adjacent permanent magnets are opposite, the coils on adjacent permanent magnets are connected in series, and the position of the coil corresponds to that of the magnetostrictive tape. It is applicable to long-term monitoring of industrial equipment such as pipelines and plates, and prediction of the remaining life of industrial equipment.

Description

Technical Field

[0001] It relates to the field of non-destructive testing technology. Background Art

[0002] During service, plates, pipe fittings, etc. often have defects such as cracks and corrosion, posing potential safety hazards. To ensure the safe operation and effective use of products, non-destructive testing has become a mandatory measure in fields such as petroleum and petrochemical, rail transit, etc. However, existing detection technologies have problems such as a small detection range, low efficiency, high cost of manual detection, and large errors. Magnetostrictive SH guided waves can propagate over a long distance and are suitable for long-term health monitoring of large plates and pipe fittings.

[0003] According to the definition of the Wiedemann effect, ferromagnetic plates and pipe fittings will generate SH guided waves under the combined action of a horizontal static magnetic field perpendicular to the sound wave propagation direction and an alternating magnetic field parallel to the sound wave propagation direction. At present, the detection devices of magnetostrictive guided wave detection systems all use pre-magnetized magnetostrictive tapes and meandering coils. The magnetostrictive tape is pasted circumferentially along the pipeline or perpendicular to the sound wave propagation direction of the plate, and a permanent magnet is used to magnetize the magnetostrictive material along this direction. Then, the meandering coil is placed on the upper surface of the magnetostrictive tape along the same direction. After passing an alternating current, an alternating magnetic field along the sound wave propagation direction is generated. On the one hand, pre-magnetization of this structural detection device results in a small bias magnetic field, and the magnetostrictive material cannot exhibit the best magnetostrictive performance, and demagnetization makes long-term monitoring impossible; on the other hand, the circumferential meandering coil structure forms a band-pass filter with a fixed center frequency, that is, it is necessary to manually replace the coil to change the working frequency of the SH guided wave, resulting in the magnetostrictive SH guided wave technology being only applicable to point-by-point detection and difficult to perform long-term monitoring on industrial plates and pipe fittings. Summary of the Invention

[0004] Aiming at the problem mentioned in the background art that the existing magnetostrictive SH guided wave technology can only be applied to point-by-point detection and is difficult to perform long-term monitoring on industrial plates and pipe fittings, the technical solution provided by this application is as follows:

[0005] A broadband magnetostrictive SH guided wave detection device for detecting defects of a workpiece to be measured, the device includes: an even number of permanent magnets, a magnetostrictive tape, coils, and a coupling agent; the magnetostrictive tape is pasted circumferentially along the workpiece to be measured at least one week through the coupling agent; the even number of permanent magnets are arranged in a circular pattern on the magnetostrictive tape, and the magnetization directions of adjacent two permanent magnets are opposite; each permanent magnet is wound with a coil, the winding directions of the coils on adjacent permanent magnets are opposite, the coils on adjacent permanent magnets are connected in series, and the coils correspond to the position of the magnetostrictive tape.

[0006] Further, the winding method of the coil is specifically as follows: continuously winding in a tight manner, that is, adjacent coils are in close contact, and the coil is wound around the middle part of the permanent magnet.

[0007] Further, the winding width of the coil is half of the SH0 guided wave wavelength.

[0008] Further, the width of the magnetostrictive tape is the same as the width of the coil, and the magnetostrictive tape is located in the middle part of the permanent magnet.

[0009] Further, the magnetostrictive tape is made of nickel, iron-cobalt alloy or iron-gallium alloy.

[0010] Based on the same inventive concept, the present invention also provides a broadband magnetostrictive SH guided wave detection method for detecting defects of a workpiece to be measured, and the method is implemented based on the device according to any one of the above solutions:

[0011] The method includes:

[0012] A range determination step for obtaining the frequency range of the alternating current signal passed into the coil according to the width of the coil;

[0013] A passing-in step for passing an alternating current signal into the coil from low to high or from high to low at a fixed step within the frequency range of the alternating current signal;

[0014] A result acquisition step for obtaining an echo signal and obtaining the defect diameter when passing alternating current signals of different frequencies.

[0015] Further, the range determination step is specifically as follows: including:

[0016] A step of collecting the main frequency of the coil corresponding to the width of the coil;

[0017] A step of obtaining the excitation signal frequency range according to the main frequency of the coil.

[0018] Further, the passing-in step is specifically as follows:

[0019] Pass an excitation signal into the coil, the frequency of the excitation signal is any frequency within the frequency range obtained in the range determination step, obtain a plurality of frequencies in sequence at a fixed step, and pass the plurality of frequencies into the coil respectively.

[0020] Further, the result acquisition step is specifically as follows: including:

[0021] A step of collecting an echo signal;

[0022] A step of obtaining the minimum amplitude according to the collected echo signal;

[0023] Steps of obtaining the corresponding frequency according to the minimum amplitude described above;

[0024] Steps of obtaining the corresponding wavelength according to the corresponding frequency described above;

[0025] Steps of determining the defect diameter according to the wavelength described above.

[0026] Based on the same inventive concept, the present invention also provides a computer-readable storage medium, which is used to store a computer program. When the computer program is executed, the broadband magnetostrictive SH guided wave detection method described above is run.

[0027] The present invention solves the problem that the existing magnetostrictive SH guided wave technology can only be applied to point-by-point detection and it is difficult to monitor industrial plates and pipe fittings for a long time. The specific advantages are as follows:

[0028] The broadband magnetostrictive SH guided wave detection device provided by the present invention realizes the ability to monitor industrial plates and pipe fittings for a long time by using the permanent magnets arranged in the permanent magnet arrangement provided by the present invention and the coils wound in the coil winding method provided in the present invention.

[0029] The broadband magnetostrictive SH guided wave detection device and method provided by the present invention use a permanent magnet array to provide a circumferential static magnetic field, improve the transducer efficiency, and solve the problem of demagnetization; secondly, the same poles of adjacent two magnets face each other, forcing the magnetic induction lines to form a closed magnetic circuit through the magnetostrictive material and the specimen, further improving the static magnetic field strength; finally, the wire winding method provided in the present application is adopted to make the current directions in adjacent coils opposite, providing an alternating magnetic field, and different frequency ranges of alternating current signals are applied according to the coil width and the magnetostrictive tape width to obtain the defect diameter, without manual replacement of the coil.

[0030] The detection device provided by the present invention not only solves the problem of demagnetization, realizes long-term monitoring, but also significantly improves the transducer efficiency of the detection device.

[0031] The broadband magnetostrictive SH guided wave detection device and method described in the present invention are applicable to long-term monitoring of industrial equipment such as pipelines and plates, and predicting the remaining life of industrial equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the broadband magnetostrictive SH guided wave detection device provided in Embodiment 1;

[0033] Figure 2 The left part is a schematic diagram of the simulation model of the 4-magnet array with the same-direction magnetization mentioned in Embodiment 1, and the right part is a schematic diagram of the static magnetic field strength tangential vector in the magnetostrictive tape of the 4-magnet array with the same-direction magnetization;

[0034] Figure 3 The left part is a schematic diagram of the simulation model of the 34-magnet array with co-directional magnetization mentioned in Embodiment 1, and the right part is a schematic diagram of the circumferential static magnetic field intensity segmentation vector in the magnetostrictive tape of the 34-magnet array with co-directional magnetization;

[0035] Figure 4 The left part is a schematic diagram of the simulation model of the 34-magnet array with alternating magnetization mentioned in Embodiment 1, and the right part is a schematic diagram of the circumferential static magnetic field intensity segmentation vector in the magnetostrictive tape of the 34-magnet array with alternating magnetization;

[0036] Figure 5 It is a schematic diagram of the experimental results for comparing the pre-magnetization methods of the Wiedemann effect;

[0037] Figure 6 It is a schematic diagram of the influence of the coil and the width of the magnetostrictive tape on the frequency response of the detection device;

[0038] Among them, in the leftmost column of coordinate points in the coordinate system, from top to bottom are the amplitudes of widths of 10.0 mm, 7.5 mm, 12.5 mm, 5.0 mm, and 2.5 mm respectively;

[0039] Figure 7 It is a schematic diagram of the detection results of frequency scanning of defects with different diameters using the detection device provided by the present invention;

[0040] Among them, a represents the detection result when the through-hole diameter is 3.0 mm, b represents the detection result when the through-hole diameter is 3.5 mm, c represents the detection result when the through-hole diameter is 4.0 mm, d represents the detection result when the through-hole diameter is 4.5 mm, e represents the detection result when the through-hole diameter is 5.0 mm, f represents the detection result when the through-hole diameter is 5.5 mm, and g represents the detection result when the through-hole diameter is 6.0 mm;

[0041] Figure 8 It is the pipeline life prediction result based on the SH guided wave frequency scanning quantitative result;

[0042] Figure 9 It is the influence of the permanent magnet lift-off distance on the bias magnetic field;

[0043] Figure 10 It is a schematic diagram of the SH guided wave excitation and reception implementation device;

[0044] Figure 11 It is a schematic diagram of the excitation and reception signals;

[0045] Among them, the left part represents the excitation and reception signals when the detection device is at position 1, and the right part represents the excitation and reception signals when the detection device is at position 2.

[0046] Among them, from top to bottom, each figure corresponds to the excitation and received signals when the excitation current frequencies are 200 kHz, 300 kHz, and 400 kHz respectively;

[0047] Among them, 1 is a permanent magnet, 2 is a magnetostrictive belt, 3 is a coil, 4 is a coupling agent, and 5 is a workpiece to be measured. Specific implementation mode

[0048] Implementation mode one, combined with Figures 1-7 Describe this implementation mode. This implementation mode provides a broadband magnetostrictive SH guided wave detection device for detecting defects of the workpiece 5 to be measured. The device includes: an even number of permanent magnets 1, a magnetostrictive belt 2, a coil 3, and a coupling agent 4; the magnetostrictive belt 2 is pasted along the circumference of the workpiece 5 to be measured for at least one week through the coupling agent 4; the even number of permanent magnets 1 are arranged in a circular manner on the magnetostrictive belt 2, and the magnetization directions of two adjacent permanent magnets 1 are opposite; a coil 3 is wound on each permanent magnet 1, the winding directions of the coils 3 on adjacent permanent magnets are opposite, the coils 3 on adjacent permanent magnets are connected in series, and the position of the coil 3 corresponds to that of the magnetostrictive belt 2.

[0049] Specifically, the device is based on the Wiedemann effect principle. The Wiedemann effect refers to that ferromagnetic materials will undergo horizontal shear deformation under the combined action of a dynamic magnetic field and a static magnetic field with perpendicular directions, thereby being able to generate SH0 guided waves. The frequency of the SH0 guided waves is the same as that of the dynamic magnetic field. Among them, the direction of the dynamic magnetic field is parallel to the propagation direction of the SH0 guided waves, and the direction of the static magnetic field is perpendicular to the propagation direction of the SH0 guided waves. When the detection device provided in this implementation mode works, it will excite and receive SH0 guided waves propagating along the axial direction of the pipeline. The permanent magnet 1 provides a static magnetic field along the circumference of the pipeline. "After the coil 3 is energized with an alternating current, a dynamic magnetic field along the axial direction of the pipeline is generated, that is, the direction of the dynamic magnetic field is parallel to the propagation direction of the SH0 guided waves, and the direction of the static magnetic field is perpendicular to the propagation direction of the SH0 guided waves. According to the Wiedemann effect, the magnetostrictive belt 2 generates SH0 guided waves under the combined action of a static magnetic field perpendicular to the sound wave propagation direction and a dynamic magnetic field parallel to the sound wave propagation direction and propagates along the axial direction of the pipeline. Since the directions of the static magnetic fields generated by adjacent permanent magnets 1 are opposite, and the current directions of the coils 3 wound on adjacent permanent magnets 1 are also opposite, the vibration directions generated in the magnetostrictive belt 2 at the same moment are the same.

[0050] Use the permanent magnet 1 to provide a static magnetic field, and change the magnitude of the static magnetic field by adjusting the relevant parameters of the permanent magnet 1 to finally obtain the optimal static magnetic field. Such as Figure 2As shown, compared with the pre-magnetization method adopted at the current stage mentioned in the background, this detection device not only solves the problem of demagnetization and realizes long-term monitoring, but also significantly improves the transducer efficiency of the detection device. In order to obtain the optimal static magnetic field, it is first necessary to determine the optimal magnitude of the static magnetic field required for the magnetostrictive tape 2 through experimental methods. Then, according to the optimal magnitude of the static magnetic field, relevant parameters of the permanent magnet 1 are determined through simulation or experimental means, including but not limited to the grade of the permanent magnet 1, the size of the permanent magnet 1, the lift-off distance between the permanent magnet 1 and the coil 3, etc.

[0051] An array of permanent magnets 1 with NS poles along the circumferential direction of the pipeline is adopted. The array of permanent magnets 1 is evenly arranged along the circumferential direction of the pipeline, and the magnetization directions of adjacent permanent magnets 1 are opposite. This structure of the array of permanent magnets 1 in cooperation with the coil 3 can enable the magnetic induction lines distributed in the circumferential direction of the pipeline to form a closed loop through the magnetostrictive tape 2, reducing the requirement for the magnetic field intensity of the permanent magnet 1 at the optimal transducer efficiency, thereby reducing the design difficulty and cost. If the magnetic pole directions of all permanent magnets 1 are the same, then the circumferentially arranged permanent magnets 1 form a closed loop by themselves, and the number of magnetic induction lines in the magnetostrictive tape 2 is significantly reduced. A permanent magnet 1 with a stronger magnetic field intensity is required to make the bias magnetic field in the magnetostrictive tape 2 reach the optimal value.

[0052] The advantages of this embodiment are as follows:

[0053] Adopting a circumferential alternating permanent magnet array can not only obtain a complete circumferential bias magnetic field, but also have the same magnetic poles of adjacent two permanent magnets 1 facing each other, which can improve the bias magnetic field intensity. As Figures 2-4 shown, a finite element simulation is carried out on the static magnetic fields generated by 3 different arrays of permanent magnets 1. Using 4 permanently magnetized permanent magnets 1 in the same direction, the circumferential magnetic field in the magnetostrictive tape 2 is a 4-period distribution. The required circumferential static magnetic field is distributed in the magnetostrictive tape 2 between adjacent two magnets, but a relatively strong reverse magnetic field will be generated directly below and in the vicinity of the permanent magnet 1. When the relative magnetic permeability of the measured workpiece 5 increases to 300, the bias magnetic field intensity in the magnetostrictive tape 2 is only 1.5 kA / m. Increasing the number of permanently magnetized permanent magnets 1 in the same direction to 34, the circumferential magnetic field in the magnetostrictive tape 2 is a 34-period distribution, and the reverse magnetic field intensity generated directly below the permanent magnet 1 is slightly less than the magnetic field intensity in the required direction. The magnetic field intensity in the required direction decreases significantly. Even if the test piece is a non-ferromagnetic material, the maximum value of the bias magnetic field intensity in the magnetostrictive tape 2 is less than 0.3 kA / m. The reason for this phenomenon is that the distance between adjacent permanent magnets 1 is small, and most of the magnetic induction lines generated by the permanent magnets 1 are closed through the permanent magnets 1. Using 34 alternately magnetized permanent magnets 1 to form a circumferential array, the circumferential magnetic field in the magnetostrictive tape 2 is a 34-period distribution. The required circumferential magnetic field is directly below the permanent magnet 1, and the circumferential magnetic field directions below adjacent two permanent magnets 1 are opposite and the magnitudes are the same. Compared with the array of permanently magnetized permanent magnets 1, the circumferential bias generated by the alternately magnetized permanent magnet array is significantly enhanced.

[0054] A permanent magnet 1 is used to provide a static magnetic field. Compared with the existing magnetostrictive SH0 guided wave detection device using the pre-magnetization method, it not only solves the problem of demagnetization of the magnetostrictive tape 2 over time and can be used for long-term monitoring, but also can effectively improve the transducer efficiency by adjusting the magnet parameters to provide a static magnetic field of the optimal size. As Figure 5 shown, when the excitation conditions are the same, under the optimal static magnetic field, the amplitude of the SH0 guided wave signal excited by the detection device is more than 3 times higher than that of the pre-magnetization method.

[0055] The width of the coil 3 is the same as that of the magnetostrictive tape 2, about half of the wavelength of the SH0 guided wave at the optimal operating frequency. By changing the widths of the coil 3 and the magnetostrictive tape 2, the center frequency and bandwidth of the detection device can be changed. Without manually replacing the coil 3, by only changing the current frequency, SH0 guided wave signals with larger amplitudes can be excited within a relatively wide frequency range, which is suitable for remotely controlling the excitation and reception of guided wave signals. Figure 6 It is the frequency response characteristic curve of the detection device when using coils 3 and magnetostrictive tapes 2 with different widths for experimental measurement. The results show that the detection device designed by the present invention can change the center frequency and bandwidth of the detection device by adjusting the widths of the coil 3 and the magnetostrictive tape 2, and achieve frequency scanning within a certain frequency range.

[0056] Using the detection device provided by the present invention, defects can be detected by frequency scanning and then quantified. However, the existing ultrasonic guided wave detection device with a fixed frequency can only detect the presence or absence of defects and cannot accurately quantify the defects. Figure 7 It is the result of frequency scanning detection of through holes with different diameters using the detection device described in the present invention. The diameter of the through hole is quantified by multiplying the wavelength corresponding to the minimum value point by 0.43, and the quantification error is almost no more than 5%.

[0057] The detection device provided by the present invention can perform long-term monitoring on industrial equipment such as pipelines and plates. By combining the defect quantification results obtained through frequency scanning detection with the monitoring time, the remaining life of industrial equipment can be predicted. Figure 8 It is the experimental result of monitoring and simulating an aluminum plate using the detection device described in the present invention, which fully demonstrates the potential of the detection device provided by the present application for defect detection.

[0058] Embodiment 2: This embodiment further limits the broadband magnetostrictive SH guided wave detection device provided in Embodiment 1. The winding method of the coil 3 is specifically: continuously winding in a tight manner, that is, adjacent coils 3 are in close contact, and the coil 3 is wound around the middle part of the permanent magnet 1.

[0059] Embodiment 3. This embodiment further limits the broadband magnetostrictive SH guided wave detection device provided in Embodiment 2. The winding width of the coil 3 is half of the wavelength of the SH0 guided wave.

[0060] The width of the coil 3 is the same as the width of the magnetostrictive strip 2 and is half of the wavelength of the SH0 guided wave at the optimal operating frequency. By changing the widths of the coil 3 and the magnetostrictive strip 2, the center frequency and bandwidth of the detection device can be changed. For the detection device provided in this application, the width of the surface force load of the workpiece 5 to be measured is approximately the same as the widths of the coil 3 and the magnetostrictive strip 2. When the force load on the specimen is evenly distributed, the displacement fields of the mass points distributed along the propagation direction of the SH0 guided wave are completely cancelled out by the mass points spaced at intervals of l / 2 wavelength. That is, when the width of the force load is less than l / 2 wavelength, the total displacement increases with the increase in the width of the force load; when the width of the force load exceeds l / 2 wavelength, an increase in the width of the force load will cause displacement cancellation and reduce the transducer efficiency. It is generally considered that the widths w of the coil 3 and the magnetostrictive strip 2 are approximately equal to the width of the force load of the specimen. Therefore, the detection device proposed in the present invention constitutes a band-pass filter with a center frequency of c / 2*w. By adjusting the widths w of the coil 3 and the magnetostrictive strip 2, the center frequency and bandwidth of the detection device can be changed. Here, c is the wave velocity of the SH0 guided wave.

[0061] Embodiment 4. This embodiment further limits the broadband magnetostrictive SH guided wave detection device provided in Embodiment 3. The width of the magnetostrictive strip 2 is the same as the width of the coil 3, and the magnetostrictive strip 2 is located in the middle part of the permanent magnet 1.

[0062] Embodiment 5. This embodiment further limits the broadband magnetostrictive SH guided wave detection device provided in Embodiment 1. There are at least two permanent magnets 1. The specific number is designed according to the diameter of the pipe to be measured and the size of the permanent magnet 1. For example: 4, 8 or 34.

[0063] Embodiment 6. This embodiment further limits the broadband magnetostrictive SH guided wave detection device provided in Embodiment 1. The magnetostrictive strip 2 is made of nickel, iron-cobalt alloy or iron-gallium alloy as the material.

[0064] Embodiment 7. This embodiment provides a broadband magnetostrictive SH guided wave detection method for detecting defects of the workpiece 5 to be measured. The method is implemented based on the device provided in any one of Embodiments 1 to 6:

[0065] The method includes:

[0066] A range determination step for obtaining the frequency range of the alternating current signal passed through the coil 3 according to the width of the coil 3;

[0067] A feeding step, for feeding an alternating current signal into the coil 3 from low to high or from high to low at a fixed step within the frequency range of the alternating current signal;

[0068] A result acquisition step, for acquiring an echo signal and the diameter of a defect when an alternating current signal of different frequencies is fed.

[0069] Wherein, the relationship among the width w, the number of turns n, and the wire diameter d of the coil 3 is:

[0070] w = n × d;

[0071] Wherein, the specific way to obtain the range of the alternating current signal is: through the relationship among the center frequency f, the sound velocity c, and the width w of the coil 3:

[0072]

[0073] First determine the center frequency f, and then obtain the range through the center frequency f. Usually, the range of 150 kHz before and after f is taken as the range for feeding the alternating current signal;

[0074] Usually, the step is taken as 1 kHz, 5 kHz, 10 kHz, or 15 kHz.

[0075] Embodiment 8. This embodiment further limits the broadband magnetostrictive SH guided wave detection method provided in Embodiment 7. The range determination step specifically includes:

[0076] A step of collecting the main frequency of the coil 3 corresponding to the width of the coil 3;

[0077] A step of obtaining the frequency range of the excitation signal according to the main frequency of the coil 3.

[0078] Embodiment 9. This embodiment further limits the broadband magnetostrictive SH guided wave detection method provided in Embodiment 7. The feeding step specifically is:

[0079] Feed an excitation signal into the coil 3. The frequency of the excitation signal is any frequency within the frequency range obtained in the range determination step. Obtain multiple frequencies in sequence at a fixed step, and feed the multiple frequencies into the coil 3 respectively.

[0080] Embodiment 10. This embodiment further limits the broadband magnetostrictive SH guided wave detection method provided in Embodiment 7. The result acquisition step specifically includes:

[0081] A step of collecting the echo signal;

[0082] A step of obtaining the minimum amplitude according to the collected echo signal;

[0083] Step of obtaining corresponding frequency according to the minimum amplitude described above;

[0084] Step of obtaining corresponding wavelength according to the corresponding frequency described above;

[0085] Step of determining defect diameter according to the wavelength described above.

[0086] Embodiment XI. This embodiment further limits the broadband magnetostrictive SH guided wave detection method provided in Embodiment VII. The result acquisition step specifically includes:

[0087] Echo acquisition step of respectively acquiring echo signals when different frequency alternating current signals are applied to coil 3 in the above-mentioned energizing step;

[0088] Step of obtaining the minimum amplitude according to the acquisition result of the echo acquisition step;

[0089] Step of obtaining corresponding frequency according to the minimum amplitude described above;

[0090] Step of obtaining corresponding wavelength according to the corresponding frequency described above;

[0091] Step of determining defect diameter according to the wavelength described above.

[0092] Embodiment XII. Combining Figures 1-11 To illustrate this embodiment, this embodiment is a specific example of exciting and receiving 300 kHz SH0 guided wave in a carbon steel pipe with a nominal diameter of 100 mm and a wall thickness of 3.5 mm provided by the detection device of the present application. Specifically:

[0093] First, determine the optimal static magnetic field magnitude of the magnetostrictive strip 2. Measure the amplitudes of the SH0 guided wave signals received by the detection device under different static magnetic field magnitudes through experiments, as Figures 2-4 shown. According to the measurement results, when the static magnetic field magnitude on the surface of the magnetostrictive strip 2 is about 200 Gs, the transducer efficiency of the detection device is the largest.

[0094] Then, use Comsol software to determine the relevant parameters of the magnet through finite element simulation. The magnet grade, size, lift-off distance between the magnet and coil 3, etc. will all affect the static magnetic field magnitude. To simplify the design process, the lift-off distance between the magnet and coil 3 is adjusted to adjust the static magnetic field magnitude. The magnet uses a common N35 neodymium iron boron magnet with dimensions of 10 mm × 10 mm × 50 mm on the market, and the magnetization direction is magnetization on the smallest surface. According to Figure 9Based on the shown simulation results, it is determined that the lift-off distance between the magnet and coil 3 is approximately 5 mm. On this basis, it is determined by fine-tuning the lift-off distance of the magnet through experimental testing. It can also be directly determined by experimental testing the lift-off distance between the magnet and coil 3. The number of magnets is determined by the pipe size and the magnet size. The outer surface circumference of the pipe is 108 mm × 3.14 ≈ 340 mm, and the width of a single magnet is 10 mm. Therefore, 34 permanent magnets 1 are arranged along the circumferential direction of the pipe in this implementation scheme.

[0095] Secondly, calculate the size of the magnetostrictive tape 2. The magnetostrictive tape 2 needs to be wound around the outer wall of the pipe. Therefore, the length of the magnetostrictive tape 2 is equal to the outer surface circumference of the pipe, that is, 108 mm × 3.14 ≈ 340 mm; the width of the magnetostrictive tape 2 is determined by the optimal operating frequency of the detection device. In the carbon steel pipe used in this implementation scheme, the sound velocity of the SH0 guided wave is about 3200 m / s, and the operating frequency is 300 kHz. According to the formula "wavelength = sound velocity / frequency", it can be known that the wavelength of the SH0 guided wave is about 10 mm. The width of the magnetostrictive tape 2 is half of the wavelength, that is, 5 mm. Therefore, a magnetostrictive tape 2 of 5 mm × 340 mm × 0.1 mm is adopted, and the thickness of the magnetostrictive tape 2 is the standard thickness of the strip provided by the manufacturer, which is 0.1 mm.

[0096] Next, design the parameters of coil 3. The coil 3 wound on each permanent magnet 1 is composed of 25 turns of 0.19 mm wide wires closely arranged side by side in the same direction. There is no clear design requirement for the number of wire turns and the wire width, but it is necessary to satisfy that the width of coil 3 is equal to the width of the magnetostrictive tape 2 of the magnetostrictive tape 2. The width of coil 3 is the product of the wire diameter and the number of turns of coil 3. In addition, the wire diameter needs to enable coil 3 to withstand the current intensity during the operation of the detection device. The coil 3 used in the present invention is hand-wound with copper wires.

[0097] Finally, install the detection device and excite / receive the guided wave. The detection device is a self-exciting and self-receiving structure and can be used to excite and receive the SH0 guided wave. As Figure 1 shown, epoxy resin is evenly applied on one side of the magnetostrictive tape 2, and the magnetostrictive tape 2 is bonded to the outer surface of the pipe to form a complete ring structure. Then, coil 3 is placed around on the surface of the magnetostrictive tape 2. Finally, 34 permanent magnets 1 are placed above coil 3 according to the detection device structure proposed by the present invention. The magnetization directions of adjacent permanent magnets 1 are opposite, and the center line of each permanent magnet 1 is aligned with the center line of coil 3. The lift-off distance between the permanent magnet 1 and coil 3 is realized by padding a layer of non-ferromagnetic material with a corresponding thickness between coil 3 and the permanent magnet 1. Use the RITEC RAM-5000SNAP ultrasonic transmitting and receiving device to excite the detection device so that it can excite and receive the SH0 guided wave in the carbon steel pipe. The experimental device is as Figure 10As shown in the figure. The detection device is installed at two positions 100 mm and 150 mm away from the pipe end face, and the detection device is excited with excitation currents of 200 kHz, 300 kHz, and 400 kHz respectively. The experimental results are as follows Figure 11 As shown. The results show that when the detection device is placed at different positions, the signal reception times are 61.8 microseconds and 92.1 microseconds respectively, and the sound velocities are 3236 m / s and 3257 m / s respectively. For every 1 mm deviation in the distance between the detection device and the end face, the deviation of the calculated sound velocity result is about 100 - 150 m / s, which is basically consistent with the theoretical sound velocity of 3200 m / s of the SH0 mode. In addition, when the excitation frequency is changed, the received signal frequency always remains consistent with the excitation signal frequency, and the sound velocity does not change, that is, the received signal has non-dispersive characteristics. Therefore, it can be proved that the detection device can excite and receive SH0 mode guided waves in the pipeline.

[0098] Embodiment Thirteen. This embodiment provides a specific example for the detection device provided by the present invention. Specifically:

[0099] Excite and receive SH guided waves in a carbon steel pipe with a nominal diameter of 108 mm and a wall thickness of 3.5 mm;

[0100] First, design the detection device. Use a copper enameled wire with a diameter of 0.19 mm to wind coil 3, and the number of turns is 25. Then the width of coil 3 is 5 mm. The center frequency of the detection device, hereinafter referred to as: main frequency, can be calculated by the formula "main frequency = sound velocity / 2 times the width of coil 3". The theoretical sound velocity of SH guided waves in the pipeline used in this embodiment is about 3200 m / s. Therefore, the main frequency of the detection device is about 320 kHz. The magnetostrictive tape 2 is wound around the pipeline circumferentially, and the width of the magnetostrictive tape 2 is the same as the width of coil 3.

[0101] Then, determine the permanent magnet 1 array parameters of the detection device. Measure the amplitudes of the SH0 guided wave signals received by the detection device under different static magnetic field magnitudes through experiments, as shown in Figure 5As shown. According to the measurement results, when the static magnetic field on the surface of the magnetostrictive tape 2 is about 200 Gs, the transducer efficiency of the detection device is the largest. Using COMSOL software, the relevant parameters of the magnet are determined through finite element simulation. The magnet grade, size, the lift-off distance between the magnet and the coil 3, etc. will all affect the magnitude of the static magnetic field. In order to simplify the design process, the magnitude of the static magnetic field is adjusted by adjusting the lift-off distance between the magnet and the coil 3. The magnet uses a common N35 neodymium iron boron magnet with dimensions of 10 mm × 10 mm × 50 mm on the market. The magnetization direction is along the circumferential direction of the pipeline, and the magnetic poles of two adjacent magnets are opposite. The number of magnets is determined by the pipeline size and the magnet size. The outer surface circumference of the pipeline is approximately 340 mm (108 mm × 3.14), and the width of a single magnet is 10 mm. Therefore, 34 permanent magnets 1 are closely arranged along the circumferential direction of the pipeline in this implementation scheme. According to the finite element simulation results, the lift-off distance between the magnet and the coil 3 is determined. On this basis, through experimental testing, the lift-off distance of the magnet is fine-tuned to determine the lift-off distance. The lift-off distance between the magnet and the coil 3 can also be directly determined through experimental testing.

[0102] Finally, install the detection device and excite / receive the guided wave. The detection device has a self-exciting and self-receiving structure and can be used to excite and receive SH guided waves. As Figure 1 shown, evenly apply epoxy resin on one side of the magnetostrictive tape 2, bond the magnetostrictive tape 2 to the outer surface of the pipeline to form a complete ring structure. Then, place the coil 3 around the surface of the magnetostrictive tape 2. Finally, place 34 permanent magnets 1 above the coil 3 according to the structure of the detection device proposed in the present invention. The magnetization directions of adjacent permanent magnets 1 are opposite, and the center line of each permanent magnet 1 is aligned with the center line of the coil 3. The lift-off distance between the permanent magnet 1 and the coil 3 is achieved by padding a layer of non-ferromagnetic material with a corresponding thickness between the coil 3 and the permanent magnet 1. Use the RITEC RAM-5000SNAP ultrasonic transmitting and receiving device to excite the detection device to excite and receive SH guided waves in the carbon steel pipeline. The experimental device is as Figure 10 shown. Install the detection device at two positions 100 mm and 150 mm away from the pipeline end face, and use sine pulse signals with frequencies of 200 kHz, 300 kHz, and 400 kHz to excite the detection device respectively. The experimental results are as Figure 11As shown. The results show that when the detection device is placed at different positions, the signal reception times are 61.8 microseconds and 92.1 microseconds respectively, and the sound speeds are 3236 m / s and 3257 m / s respectively; for every 1 mm deviation in the distance between the detection device and the end face, the deviation of the calculated sound speed is about 100 - 150 m / s, which is basically consistent with the theoretical sound speed of 3200 m / s of the SH guided wave in the SH0 mode. In addition, when the excitation frequency is changed, the frequency of the received signal is always consistent with the excitation signal frequency, and the sound speed does not change, that is, the received signal has non-dispersive characteristics. Therefore, it can be proved that this detection device can excite and receive SH guided waves in the SH0 mode in the pipeline.

[0103] Embodiment Fourteen: This embodiment provides a specific example for the detection device provided by the present invention. Specifically:

[0104] Perform quantitative detection on the through-hole defects in a 2-mm-thick aluminum plate;

[0105] First, design and install the detection device. Unfold the detection device in Embodiment One and install it on an aluminum plate with a wall thickness of 2 mm as the transmitting detection device for exciting SH guided waves. Use an electromagnetic ultrasonic detection device based on the Lorentz force principle as the receiving detection device. Process through-hole defects with diameters of 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, and 6 mm at a distance of 500 mm from the transmitting detection device. The receiving detection device is located between the transmitting detection device and the through-hole defect, 150 mm away from the transmitting detection device.

[0106] Then, perform frequency scanning detection on the through-hole defects. The main frequency of the detection device used in this embodiment is about 320 kHz. Therefore, the frequency scanning range is set to 200 kHz - 500 kHz, and the detection frequency interval is 15 kHz each time, that is, 200 kHz, 215 kHz, 230 kHz, etc., until the frequency reaches 500 kHz. Use the RITEC RAM-5000SNAP ultrasonic transmitting and receiving device to excite the detection device, and the excitation signal is a 10-cycle sine pulse signal with frequencies of 200 kHz, 215 kHz, 230 kHz, etc., until 500 kHz. Record the amplitudes of the SH guided wave signals excited by the transmitting detection device received by the receiving detection device and the amplitudes of the through-hole defect echo signals at each frequency.

[0107] Finally, perform quantitative analysis on the through-hole defects. Divide the amplitude of the through-hole defect echo signal received by the receiving detection device at the same frequency by the amplitude of the SH guided wave signal excited by the transmitting detection device received by the receiving detection device as the amplitude of the through-hole defect reflection signal ignoring the frequency response difference of the detection device. Plot the curve of the amplitude of this through-hole defect reflection signal versus frequency, as Figure 6As shown, determine the frequency corresponding to the minimum amplitude value within the frequency scanning range. Calculate the wavelength based on this frequency. The theoretical sound velocity of SH guided waves in a 2-mm-thick aluminum plate is approximately 3,100 m / s, and the wavelength can be calculated using the formula "wavelength = sound velocity / frequency". Multiply the wavelength by 0.43 times, which is the diameter of the through-hole defect. According to this method, the quantitative results of the through-hole defect diameter are as follows: for a 3-mm-diameter through-hole, the quantitative result is 3.19 mm, with a relative quantitative error of 6.33%; for a 3.5-mm-diameter through-hole, the quantitative result is 3.56 mm, with a relative quantitative error of 1.71%; for a 4-mm-diameter through-hole, the quantitative result is 4.23 mm, with a relative quantitative error of 5.75%; for a 4.5-mm-diameter through-hole, the quantitative result is 4.67 mm, with a relative quantitative error of 3.78%; for a 5-mm-diameter through-hole, the quantitative result is 4.92 mm, with a relative quantitative error of -1.60%; for a 5.5-mm-diameter through-hole, the quantitative result is 5.5 mm, with a relative quantitative error of 0%; for a 6-mm-diameter through-hole, the quantitative result is 5.89 mm, with a relative quantitative error of -1.83%.

[0108] Embodiment 15. This embodiment provides a computer-readable storage medium for storing a computer program, which, when executed, runs the broadband magnetostrictive SH guided wave detection method provided by the present invention.

[0109] The above further elaborates on several specific embodiments of the present invention through specific implementation manners. However, the above-mentioned several embodiments are only several relatively preferred embodiments of the present invention and are not used as limitations of the present invention. Any modifications, improvements to the implementation manners, substitutions, combinations, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A broadband magnetostrictive SH guided wave detection device for detecting defects of a workpiece to be measured (5), characterized in that, The described device includes: an even number of permanent magnets (1), a magnetostrictive tape (2), a coil (3), and a coupling agent (4); the magnetostrictive tape (2) is adhered circumferentially around the workpiece to be measured (5) for at least one turn through the coupling agent (4); the even number of permanent magnets (1) are arranged in a circular manner on the magnetostrictive tape (2), and the magnetization directions of two adjacent permanent magnets (1) are opposite; a coil (3) is wound around each permanent magnet (1), the winding directions of the coils (3) on adjacent permanent magnets are opposite, the coils (3) on adjacent permanent magnets are connected in series, and the position of the coil (3) corresponds to that of the magnetostrictive tape (2); The coil (3) is wound around the middle part of the permanent magnet (1), The winding width of the coil (3) is half of the SH0 guided wave wavelength; The width of the magnetostrictive tape (2) is the same as that of the coil (3), and the magnetostrictive tape (2) is located in the middle part of the permanent magnet (1).

2. The broadband magnetostrictive SH guided wave detection device according to claim 1, characterized in that, The winding method of the coil (3) is specifically: continuously winding in a tight manner, that is, adjacent coils (3) are in close contact.

3. The broadband magnetostrictive SH guided wave detection device according to claim 1, characterized in that, The magnetostrictive tape (2) is made of nickel, iron-cobalt alloy or iron-gallium alloy as the material.

4. A broadband magnetostrictive SH guided wave detection method for detecting defects in a workpiece to be measured (5), characterized in that, The described method is implemented based on the device according to any one of claims 1 to 3: The described method includes: A range determination step for obtaining the frequency range of the alternating current signal applied to the coil (3) according to the width of the coil (3); An application step for applying an alternating current signal to the coil (3) from low to high or from high to low in a fixed step within the frequency range of the alternating current signal; A result acquisition step for obtaining an echo signal and the diameter of a defect when applying alternating current signals of different frequencies.

5. The broadband magnetostrictive SH guided wave detection method according to claim 4, wherein The range determination step is specifically: including: A step of collecting the main frequency of the coil (3) corresponding to the width of the coil (3); A step of obtaining the excitation signal frequency range according to the main frequency of the coil (3).

6. The broadband magnetostrictive SH guided wave detection method according to claim 4, characterized in that The application step is specifically: Applying an excitation signal to the coil (3), the frequency of the excitation signal is any frequency within the frequency range obtained in the range determination step, obtaining multiple frequencies in sequence according to a fixed step, and respectively applying the multiple frequencies to the coil (3).

7. The broadband magnetostrictive SH guided wave detection method according to claim 4, wherein, The result acquisition step is specifically: including: A step of collecting an echo signal; A step of obtaining the minimum amplitude according to the collected echo signal; A step of obtaining the corresponding frequency according to the minimum amplitude; A step of obtaining the corresponding wavelength according to the corresponding frequency; A step of determining the defect diameter according to the wavelength.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program, and when the computer program is executed, it runs the broadband magnetostrictive SH guided wave detection method according to any one of claims 5 - 7.

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