High-order torsional mode flexible magnetostrictive phased array guided wave sensor

Abstract

The invention provides a high-order torsional mode flexible magnetostriction phased array guided wave sensor which comprises a double-layer flexible circuit board, at least one excitation coil is arranged in the double-layer flexible circuit board, and flexible silica gel shells are arranged on the two sides of the double-layer flexible circuit board. An iron-cobalt alloy belt is arranged on the lower side of a flexible silica gel shell arranged on the lower side of the double-layer flexible circuit board in an attached mode, the iron-cobalt alloy belt is pasted on a carbon steel pipeline to be detected through epoxy resin, and the flexible silica gel shell is connected with a signal processing and analyzing device through a switching circuit board. According to the invention, the precision and sensitivity of defect detection are improved by virtue of the shorter wavelength of the frequency dispersion guided wave, meanwhile, the axial and circumferential resolution of defect detection in the pipeline is enhanced by utilizing a phased array detection mode of a multi-sensor array element, and automatic remote monitoring and long-term evaluation of the health condition of the carbon steel pipeline are realized.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic nondestructive testing and ultrasonic imaging, and in particular to a high-order torsional mode flexible magnetostrictive phased array guided wave sensor. Background Art

[0002] Long-distance pipelines are widely used in the fields of petrochemical, natural gas transportation, domestic water and sewage treatment. With the rapid development of the energy industry and manufacturing industry, long-distance pipelines are often in various complex working conditions, such as high humidity, high salt and strong corrosive environment. Conventional non-destructive testing methods require scanning or excavation of pipelines section by section, which consumes a lot of manpower and material resources in complex working conditions, and the detection efficiency is low. The detection method based on ultrasonic guided waves has the advantages of single-point excitation, long detection distance and high scanning efficiency, so it is very suitable for continuous detection of carbon steel pipelines. Commonly used ultrasonic guided wave detection sensors include ultrasonic guided wave sensors based on piezoelectric chip excitation, magnetostrictive ultrasonic guided wave sensors and electromagnetic pulse ultrasonic guided wave sensors. These three types of ultrasonic guided wave sensors each have their own unique advantages and disadvantages. For example, although the piezoelectric chip ultrasonic guided wave sensor has good excitation efficiency and signal-to-noise ratio, it is difficult to achieve large-area mechanical coupling due to the limitation of its own rigid structure under the condition that the curvature of the measured pipeline surface changes extremely drastically. Although it can be used with coupling agents, the energy loss is severe. There are similarities between electromagnetic pulse ultrasonic guided wave sensors and magnetostrictive ultrasonic guided wave sensors. Both use high-frequency alternating electromagnetic fields to generate guided wave excitation signals to achieve detection, but the efficiency of electromagnetic pulse ultrasonic guided wave sensors in exciting torsional guided wave modes is lower than that of magnetostrictive ultrasonic guided wave sensors. At present, the magnetostrictive ultrasonic guided wave sensors widely used in industry mainly use zero-order non-dispersive modal torsional guided waves. This mode has stable phase velocity and group velocity, but its application scenarios are limited to the low-frequency range. High-order modal torsional guided waves have shorter wavelengths and higher sensitivity, but there are currently few reports on high-order modal torsional guided wave detection sensors based on the magnetostrictive principle. In summary, achieving higher frequency and higher resolution detection based on the magnetostrictive guided wave detection and excitation principle is a new problem that needs to be solved in the field of non-destructive testing.

[0003] For example, the invention patent with application number: 201710790221.7 discloses a torsional modal guided wave magnetostrictive sensor based on a double-ring permanent magnet array. The sensor mainly includes two symmetrical half-ring sensor components, which are coated on the pipeline surface through elastic snap-on connection. Each half-ring sensor component mainly includes a double-row permanent magnet array, two iron-cobalt alloy strips, a detection coil, a rubber shell and an epoxy resin layer. The two iron-cobalt alloy strips are pre-bent into an arc to adapt to the outer diameter of the measured pipeline, and the two sides are fixed by a molded base. The detection coil is wound around the two iron-cobalt alloy strips at a fixed spacing, and an alternating current is passed to form an alternating magnetic field along the length direction of the iron-cobalt alloy strip. The rectangular permanent magnets in the double-row permanent magnet array are all adsorbed on the outside of the iron-cobalt alloy strip in the same direction, providing a static magnetic field along the width direction of the iron-cobalt alloy strip. The two sets of detection coils in the sensor are passed through an AC signal with a phase difference of 90° to generate a direction-controllable torsional modal guided wave for pipeline defect detection. The above inventions show a high signal-to-noise ratio in detection, but the sensor structure is a single-element excitation coil, so it has axial resolution in defect detection but insufficient ability to locate the circumferential position of the defect. Compared with invention patent 201710790221.7, the present invention uses a phased array waveguide sensor composed of multiple elements to realize the excitation and reception of torsional mode waveguide signals in the pipeline, which not only has axial resolution of defects, but also can realize circumferential positioning detection of defects, thus having higher spatial positioning accuracy of defects in the pipeline. Summary of the invention

[0004] In view of the technical problem that the existing technology cannot achieve higher frequency and higher resolution detection based on the magnetostrictive guided wave detection and excitation principle, the present invention proposes a high-order torsional mode flexible magnetostrictive phased array guided wave sensor, which is beneficial to significantly improve the detection efficiency and accuracy of defects.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the present invention is implemented as follows: a high-order torsional mode flexible magnetostrictive phased array guided wave sensor, including a double-layer flexible circuit board, at least one excitation coil is arranged in the double-layer flexible circuit board, flexible silicone shells are arranged on both sides of the double-layer flexible circuit board, and an iron-cobalt alloy belt is bonded to the lower side of the flexible silicone shell arranged on the lower side of the double-layer flexible circuit board. The iron-cobalt alloy belt is adhered to the carbon steel pipeline to be tested by epoxy resin, and the flexible silicone shell is connected to the signal processing and analysis device through a adapter circuit board.

[0006] The double-layer flexible circuit board includes an upper flexible circuit board and a lower flexible circuit board of equal size and consistent shape. The lower flexible circuit board is connected to the upper flexible circuit board through a via pad structure. An excitation coil is arranged in the upper flexible circuit board and the lower flexible circuit board. The end pad structure is arranged on one side of the upper flexible circuit board. A flexible silicone shell is arranged on the upper side of the upper flexible circuit board and the lower side of the lower flexible circuit board.

[0007] The flexible silicone shell includes an upper flexible silicone shell and a lower flexible silicone shell. The upper flexible silicone shell is arranged on the top of the upper flexible circuit board, and the lower flexible silicone shell is arranged on the bottom of the lower flexible circuit board. A transfer circuit board is arranged on one side of the upper flexible silicone shell, which is connected to the excitation coil through an end pad structure. A high-voltage connection socket is arranged on the transfer circuit board, and the lower flexible silicone shell is tightly fitted with a high magnetostrictive iron-cobalt alloy strip.

[0008] The excitation coil includes at least one coil finger, the coil fingers are arranged in parallel in sequence, adjacent coil fingers are connected, and the coil finger farthest from the end pad structure is connected to the end pad structure.

[0009] The width of the coil finger structure is the same as the wavelength of the excited high-order torsional mode guided wave.

[0010] The coil finger includes a first forward current wire, a second forward current wire, a first reverse current wire, a second reverse current wire and at least one transverse wire which are arranged in parallel in sequence, one end of the first forward current wire is connected to one end of the second reverse current wire through the transverse wire, the other end of the first forward current wire is connected to the other end of the second reverse current wire in the adjacent coil finger far away from the end pad structure through the transverse wire, the other end of the second reverse current wire is connected to the other end of the first forward current wire in the adjacent coil finger close to the end pad structure through the transverse wire, one end of the second forward current wire and one end of the first reverse current wire are connected through the transverse wire, the other end of the second forward current wire is connected to the other end of the first reverse current wire in the adjacent coil finger far away from the end pad structure through the transverse wire, the other end of the first reverse current wire is connected to the other end of the second forward current wire in the adjacent coil finger close to the end pad structure through the transverse wire, the other end of the second forward current wire in the coil finger farthest from the end pad structure is connected to the end pad structure through the transverse wire, and the other end of the second reverse current wire in the coil finger closest to the end pad structure is provided with a via pad.

[0011] The signal processing and analysis device comprises a magnetostrictive ultrasonic guided wave imaging system and a host computer. The high-voltage connection socket is connected to the magnetostrictive ultrasonic guided wave imaging system through a high-voltage connection socket I, a multi-channel signal transmission cable and a high-voltage connection socket II which are connected in sequence. The magnetostrictive ultrasonic guided wave imaging system and the host computer are connected by wireless signals. The magnetostrictive ultrasonic guided wave imaging system is connected to at least one guided wave sensor.

[0012] The iron-cobalt alloy strip is an iron-cobalt alloy strip with high magnetostriction.

[0013] The method of use is as follows: first, at least one waveguide sensor is fixed on the carbon steel pipeline to be tested, a permanent magnet is placed on one side of the carbon steel pipeline to be tested, and the iron-cobalt alloy strip is pre-magnetized by the permanent magnet. Subsequently, a double-layer flexible circuit board wrapped in a flexible silicone shell is attached to the surface of the iron-cobalt alloy strip, at least one waveguide sensor is connected to a magnetostrictive ultrasonic guided wave imaging system, and a host computer is used to control the magnetostrictive ultrasonic imaging system to excite and collect waveguide signals, obtain detection waveforms, and analyze detection results;

[0014] During the detection process, the host computer controls the magnetostrictive ultrasonic guided wave imaging system to emit excitation signal pulses, which are transmitted to the waveguide sensor via a multi-channel signal transmission cable, thereby generating a high-frequency alternating electromagnetic field, generating a second-order dispersive modal torsional ultrasonic guided wave in the high magnetostrictive iron-cobalt alloy strip, and coupling the mechanical vibration to the carbon steel pipeline to be tested. The dispersive modal torsional ultrasonic guided wave encounters defects in the carbon steel pipeline to be tested and generates reflections. The reflected guided wave components are received by the sensor and transmitted to the magnetostrictive ultrasonic guided wave imaging system, and then transmitted to the host computer via wireless signals, which performs waveform detection and result analysis.

[0015] The method for fixing at least one waveguide sensor on the carbon steel pipeline to be tested is: using epoxy resin to fix the iron-cobalt alloy strip on the carbon steel pipeline to be tested.

[0016] The beneficial effects of the present invention are:

[0017] 1) The present invention proposes a high-order torsional mode flexible magnetostrictive phased array guided wave sensor containing 16 array elements. The sensor is attached to the surface of the carbon steel pipeline to be tested in a flexible bonding manner for detection. No mechanical installation is required in advance, and the detection and removal process is simple and practical.

[0018] 2) The present invention proposes a second-order dispersive modal torsional ultrasonic guided wave excitation method based on the Widmann magnetostrictive effect and the propagation characteristics of high-order dispersive torsional guided wave modes. Compared with the zero-order non-dispersive modal torsional guided wave, this modal wave has a shorter wavelength and a higher excitation frequency, thereby bringing higher temporal and spatial resolution.

[0019] 3) The high-order torsional modal flexible magnetostrictive phased array guided wave sensor with 16 array elements proposed in the present invention performs simultaneous circumferential and axial scanning of the pipeline by superimposing the results of multiple array elements. Compared with a single-element torsional guided wave sensor, it has higher detection accuracy and can achieve simultaneous axial and circumferential positioning of defects.

[0020] 4) The magnetostrictive ultrasonic guided wave detection system proposed in the present invention controls the magnetostrictive ultrasonic imaging system in the form of a Wifi wireless hotspot through the control software of a thin and light host laptop computer, without the need for wired connection, and can achieve remote real-time monitoring of the health status of carbon steel pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a cross-sectional view of the flexible magnetostrictive phased array guided wave sensor of the present invention;

[0023] Figure 2 It is a schematic diagram of the coil structure of the magnetostrictive sensor;

[0024] Figure 3 A schematic diagram of the present invention for detecting a carbon steel pipeline;

[0025] Figure 4 Schematic diagram of the standard sample tube used in the example;

[0026] Figure 5 This is a waveform diagram of the signal obtained by using a magnetostrictive ultrasonic guided wave detection system to detect a standard sample tube.

[0027] In the figure, 1 is a high-voltage connection socket, 21 is a first forward current wire, 22 is a second forward current wire, 31 is a first reverse current wire, 32 is a second reverse current wire, 4 is an upper flexible silicone shell, 5 is a double-layer flexible circuit board, 6 is a lower flexible silicone shell, 7 is a carbon steel pipeline to be tested, 8 is a switching circuit board, 9 is an iron-cobalt alloy belt, 10 is epoxy resin, 11 is a permanent magnet, 12 is a high-voltage connection socket I, 13 is a multi-channel signal transmission cable, 14 is a high-voltage connection socket II, 15 is a magnetostrictive ultrasonic guided wave imaging system, 16 is a wireless signal, and 17 is a host computer. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1As shown, a high-order torsional mode flexible magnetostrictive phased array guided wave sensor includes a double-layer flexible circuit board 5, in which at least one excitation coil is arranged. Flexible silicone shells are arranged on both sides of the double-layer flexible circuit board 5, and an iron-cobalt alloy belt 9 is bonded to the lower side of the flexible silicone shell arranged on the lower side of the double-layer flexible circuit board 5. The iron-cobalt alloy belt 9 is bonded to the carbon steel pipeline 7 to be tested through epoxy resin 10. The flexible silicone shell is connected to the signal processing and analysis device through a transfer circuit board 8.

[0030] Specifically, the double-layer flexible circuit board 5 is mainly used to improve the excitation and receiving efficiency of the torsional waveguide in the pipeline. The flexible silicone shell is mainly used for the encapsulation and insulation protection of the sensor circuit structure. The excitation coil is mainly used to generate and receive high-frequency alternating electromagnetic signals in the pipeline. The iron-cobalt alloy strip 9 is mainly used to realize the transmission of the mechanical displacement of the torsional waveguide with the carbon steel pipeline 7 to be tested. The iron-cobalt alloy strip 9 is an iron-cobalt alloy strip with a high magnetostriction rate. The permanent magnet 11 is mainly used to generate a magnetic field. The permanent magnet 11 uses a nylon-iron-boron permanent magnet. The bias magnetic field generated by the nylon-iron-boron permanent magnet realizes magnetization, avoids the frequency doubling vibration effect generated under the action of the high-frequency alternating electromagnetic field, and realizes efficient excitation of high-order torsional modal waveguides.

[0031] The flexible silicone shell includes an upper flexible silicone shell 4 and a lower flexible silicone shell 6. The upper flexible silicone shell 4 is arranged on the top of the upper flexible circuit board, and the lower flexible silicone shell 6 is arranged at the bottom of the lower flexible circuit board. A transfer circuit board 8 is arranged on one side of the upper flexible silicone shell 4, and is connected to the excitation coil through the end pad structure. A high-voltage connection socket 1 is arranged on the transfer circuit board 8, and the lower flexible silicone shell 6 is tightly fitted with a high magnetostrictive iron-cobalt alloy belt. There is no need to achieve permanent mechanical coupling by bonding. The transfer circuit board 8 is mainly used to realize the circuit transition between the high-voltage connection socket and the excitation coil. The high-voltage connection socket 1 is mainly used to connect the waveguide sensor to the signal processing and analysis device.

[0032] The double-layer flexible circuit board 5 includes an upper flexible circuit board and a lower flexible circuit board of equal size and consistent shape, such as Figure 3As shown, the lower flexible circuit board is connected to the upper flexible circuit board through a via pad structure, an excitation coil is provided in both the upper flexible circuit board and the lower flexible circuit board, the end pad structure is provided on one side of the upper flexible circuit board, and a flexible silicone shell is provided on the upper side of the upper flexible circuit board and the lower side of the lower flexible circuit board. The use of a multi-layer flexible circuit board structure can significantly increase the intensity of the alternating electromagnetic field, thereby improving the excitation and receiving efficiency of the torsional waveguide in the pipeline. The excitation coil includes at least one coil finger, the coil fingers are arranged in parallel in sequence, the adjacent coil fingers are connected, and the coil finger farthest from the end pad structure is connected to the end pad structure. The width of the coil finger structure is the same as the wavelength of the excited high-order torsional mode waveguide. According to the dispersion relationship of the torsional waveguide mode in the pipeline, this setting can excite the dispersion waveguide of the same wavelength mode in the pipeline.

[0033] Specifically, Figure 2 As shown, the coil finger includes a first forward current wire 21, a second forward current wire 22, a first reverse current wire 31, a second reverse current wire 32 and at least one transverse wire arranged in parallel in sequence, one end of the first forward current wire 21 and one end of the second reverse current wire 32 are connected through the transverse wire, and the other end of the first forward current wire 21 is connected to the other end of the second reverse current wire 32 in the adjacent coil finger away from the end pad structure through the transverse wire. The other end of the second reverse current wire 32 is connected to the other end of the first forward current wire 21 in the adjacent coil finger close to the end pad structure through the transverse wire. One end of the second forward current wire 22 and one end of the first reverse current wire 31 are connected through the transverse wire, the other end of the second forward current wire 22 is connected to the other end of the first reverse current wire 31 in the adjacent coil finger away from the end pad structure through the transverse wire, and the other end of the first reverse current wire 31 is connected to the other end of the second forward current wire 22 in the adjacent coil finger close to the end pad structure through the transverse wire. The other end of the second forward current wire 22 in the coil finger farthest from the end pad structure is connected to the end pad structure through a transverse wire, and the other end of the second reverse current wire 32 in the coil finger closest to the end pad structure is provided with a via pad.

[0034] The signal processing and analysis device includes a magnetostrictive ultrasonic guided wave imaging system 15 and a host computer 17. The high-voltage connection socket 1 is connected to the magnetostrictive ultrasonic guided wave imaging system 15 through the high-voltage connection socket Ⅰ12, the multi-channel signal transmission cable 13 and the high-voltage connection socket Ⅱ14 connected in sequence. The magnetostrictive ultrasonic guided wave imaging system 15 and the host computer 17 are connected by wireless signals, and the wireless signal can be WiFi. The magnetostrictive ultrasonic guided wave imaging system 15 is mainly used to generate an excitation signal, realize the reception of the guided wave signal and transmit it to the notebook host computer for data post-processing, and the host computer 17 is mainly used to analyze the guided wave signal. The high-voltage connection socket Ⅰ12, the multi-channel signal transmission cable 13 and the high-voltage connection socket Ⅱ14 are mainly used to transmit the information collected by the guided wave sensor to the magnetostrictive ultrasonic guided wave imaging system 15.

[0035] like Figure 4 As shown, a specific method for using a high-order torsional mode flexible magnetostrictive phased array guided wave sensor is as follows: first, an iron-cobalt alloy strip 9 is fixed on a carbon steel pipe 7 to be tested using epoxy resin 10. A permanent magnet 11 is placed on one side of the carbon steel pipe 7 to be tested, and the iron-cobalt alloy strip 9 is pre-magnetized using the permanent magnet 11. Subsequently, a double-layer flexible circuit board 5 wrapped in a flexible silicone shell is attached to the surface of the iron-cobalt alloy strip 9, and the guided wave sensor is connected to a magnetostrictive ultrasonic guided wave imaging system 15. The upper computer 17 is used to control the magnetostrictive ultrasonic imaging system 15 to excite and collect guided wave signals, obtain detection waveforms, and analyze detection results.

[0036] During the detection process, the host computer 17 controls the magnetostrictive ultrasonic guided wave imaging system 15 to emit an excitation signal pulse, which is transmitted to the waveguide sensor via the multi-channel signal transmission cable 13, thereby generating a high-frequency alternating electromagnetic field, generating a second-order dispersive modal torsion ultrasonic guided wave in the high magnetostrictive iron-cobalt alloy belt, and coupling the mechanical vibration to the carbon steel pipeline 7 to be tested. The dispersive modal torsion ultrasonic guided wave encounters the defects in the carbon steel pipeline 7 to be tested and generates reflection. The reflected guided wave component is received by the sensor and transmitted to the magnetostrictive ultrasonic guided wave imaging system 15, and transmitted to the host computer 17 via the wireless signal 16, and the host computer 17 performs waveform detection and result analysis. Among them, the wireless signal 16 can be a WiFi signal.

[0037] Figure 5 The sample pipe used for testing is a carbon steel pipe with a length of 2m and a diameter of 350mm. In this application, 16 waveguide sensors are used, and the 16 waveguide sensors are evenly fixed on the vertical section of the carbon steel pipe 7 to be tested. The defect echo signal obtained after the magnetostrictive sensor is installed on the pipe is as follows: Figure 5 As shown, it can be seen that the torsional mode flexible magnetostrictive phased array guided wave sensor is able to detect and locate defects on carbon steel pipelines.

[0038] The present invention proposes a high-order torsional modal flexible magnetostrictive phased array waveguide sensor and a magnetostrictive ultrasonic waveguide detection system containing the sensor. The sensor can be used to detect the carbon steel pipeline to be tested by simply fitting it in place. The reception of the waveguide signal and the real-time monitoring of the health status can be completed through wireless communication. Pre-magnetizing the iron-cobalt magnetostrictive strip using a nebium-iron-boron permanent magnet can significantly improve the excitation efficiency of the torsional modal waveguide and avoid the frequency doubling effect, thereby exciting a second-order dispersion modal torsional ultrasonic waveguide with a pure modality, which is beneficial to significantly improve the detection efficiency and accuracy of defects.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-order torsional mode flexible magnetostrictive phased array guided wave sensor, characterized in that: The invention comprises a double-layer flexible circuit board (5), at least one excitation coil is arranged in the double-layer flexible circuit board (5), flexible silicone shells are arranged on both sides of the double-layer flexible circuit board (5), an iron-cobalt alloy strip (9) is bonded to the lower side of the flexible silicone shell arranged on the lower side of the double-layer flexible circuit board (5), the iron-cobalt alloy strip (9) is bonded to the carbon steel pipeline (7) to be tested through epoxy resin (10), and the flexible silicone shell is connected to the signal processing and analysis device through a switching circuit board (8).

2. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 1, characterized in that: The double-layer flexible circuit board (5) comprises an upper flexible circuit board and a lower flexible circuit board of equal size and consistent shape; the lower flexible circuit board is connected to the upper flexible circuit board via a via pad structure; an excitation coil is arranged in both the upper flexible circuit board and the lower flexible circuit board; the terminal pad structure is arranged on one side of the upper flexible circuit board; and a flexible silicone shell is arranged on the upper side of the upper flexible circuit board and on the lower side of the lower flexible circuit board.

3. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 2, characterized in that: The flexible silicone shell comprises an upper flexible silicone shell (4) and a lower flexible silicone shell (6); the upper flexible silicone shell (4) is arranged on the top of the upper flexible circuit board, and the lower flexible silicone shell (6) is arranged on the bottom of the lower flexible circuit board; a switching circuit board (8) is arranged on one side of the upper flexible silicone shell (4) and is connected to the excitation coil via an end pad structure; a high-voltage connection socket (1) is arranged on the switching circuit board (8); and the lower flexible silicone shell (6) is tightly fitted to a high magnetostrictive iron-cobalt alloy strip.

4. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 3, characterized in that: The excitation coil includes at least one coil finger, the coil fingers are arranged in parallel in sequence, adjacent coil fingers are connected, and the coil finger farthest from the end pad structure is connected to the end pad structure.

5. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 4, characterized in that: The width of the coil finger structure is the same as the wavelength of the excited high-order torsional mode guided wave.

6. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 4 or 5, characterized in that: The coil finger comprises a first forward current wire (21), a second forward current wire (22), a first reverse current wire (31), a second reverse current wire (32) and at least one transverse wire which are arranged in parallel in sequence; one end of the first forward current wire (21) and one end of the second reverse current wire (32) are connected via the transverse wire; the other end of the first forward current wire (21) is connected to the other end of the second reverse current wire (32) in an adjacent coil finger away from the terminal pad structure via the transverse wire; the other end of the second reverse current wire (32) is connected to the other end of the first forward current wire (21) in an adjacent coil finger close to the terminal pad structure via the transverse wire; 2) is connected to one end of the first reverse current wire (31) through a transverse wire, the other end of the second forward current wire (22) is connected to the other end of the first reverse current wire (31) in the adjacent coil finger far away from the end pad structure through the transverse wire, the other end of the first reverse current wire (31) is connected to the other end of the second forward current wire (22) in the adjacent coil finger close to the end pad structure through the transverse wire, the other end of the second forward current wire (22) in the coil finger farthest from the end pad structure is connected to the end pad structure through the transverse wire, and the other end of the second reverse current wire (32) in the coil finger closest to the end pad structure is provided with a via pad.

7. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 6, characterized in that: The signal processing and analysis device comprises a magnetostrictive ultrasonic guided wave imaging system (15) and a host computer (17); the high-voltage connection socket (1) is connected to the magnetostrictive ultrasonic guided wave imaging system (15) through a high-voltage connection socket I (12), a multi-channel signal transmission cable (13) and a high-voltage connection socket II (14) which are connected in sequence; the magnetostrictive ultrasonic guided wave imaging system (15) and the host computer (17) are connected by wireless signals (16); and the magnetostrictive ultrasonic guided wave imaging system (15) is connected to at least one guided wave sensor.

8. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 7, characterized in that: The iron-cobalt alloy strip (9) is an iron-cobalt alloy strip with a high magnetostriction rate.

9. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 8, characterized in that: The method of use is as follows: first, at least one waveguide sensor is fixed on a carbon steel pipeline (7) to be tested, a permanent magnet (11) is placed on one side of the carbon steel pipeline (7) to be tested, and an iron-cobalt alloy strip (9) is pre-magnetized by using the permanent magnet (11). Subsequently, a double-layer flexible circuit board (5) wrapped in a flexible silicone shell is attached to the surface of the iron-cobalt alloy strip (9), at least one waveguide sensor is connected to a magnetostrictive ultrasonic waveguide imaging system (15), and a host computer (17) is used to control the magnetostrictive ultrasonic imaging system (15) to excite and collect waveguide signals, obtain detection waveforms, and analyze detection results; During the detection process, the magnetostrictive ultrasonic guided wave imaging system (15) is controlled by the host computer (17) to emit an excitation signal pulse, which is transmitted to the waveguide sensor via the multi-channel signal transmission cable (13), thereby generating a high-frequency alternating electromagnetic field, generating a second-order dispersive modal torsion ultrasonic guided wave in the high magnetostrictive iron-cobalt alloy strip, and coupling the mechanical vibration to the carbon steel pipeline (7) to be tested. The dispersive modal torsion ultrasonic guided wave is reflected after encountering defects in the carbon steel pipeline (7) to be tested. The reflected guided wave component is received by the sensor and transmitted to the magnetostrictive ultrasonic guided wave imaging system (15), and then transmitted to the host computer (17) via a wireless signal (16). The host computer (17) performs waveform detection and result analysis.

10. The high-order torsional mode flexible magnetostrictive phased array guided wave sensor according to claim 9, characterized in that: The method for fixing at least one waveguide sensor on the carbon steel pipeline to be tested comprises: using epoxy resin (10) to fix an iron-cobalt alloy strip (9) on the carbon steel pipeline (7) to be tested.

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