Automatic noise reduction type magnetostrictive guided wave monitoring transducer

Abstract

The invention discloses an automatic noise reduction type magnetostrictive guided wave monitoring transducer. The sensor shell is placed on a to-be-tested sample, the electromagnetic noise receiving sensor, the excitation sensor, the phase inverter, the summator and the damping spring are all located in the sensor shell, and the electromagnetic noise receiving sensor and the excitation sensor are both fixedly connected to the upper surface of the to-be-tested sample. Damping springs are arranged above the electromagnetic noise receiving sensor and the excitation sensor, the excitation sensor is connected with the adder through a phase inverter, the electromagnetic noise receiving sensor is connected with the adder through a cable, the electromagnetic noise receiving sensor and the excitation sensor are respectively provided with an enameled wire and a backing layer, and the enameled wires are wound on the backing layers. Electromagnetic noise is effectively filtered, guided wave signals are amplified, accuracy of guided wave monitoring data is improved, influence of interference signals on monitoring results is avoided, the noise reduction type transducer can effectively suppress the interference signals, and the service life of the transducer is prolonged.

Description

Technical Field

[0001] The invention belongs to the cross field of magnetostrictive sensors and guided wave monitoring, and in particular relates to an automatic noise reduction type magnetostrictive guided wave monitoring transducer. Background Art

[0002] In long-term monitoring of guided waves, magnetostrictive sensors are often used to excite and receive guided wave signals. However, under conditions of poor electromagnetic environment, the sensor will be affected by the surrounding electromagnetic interference, causing signal contamination and interference. These electromagnetic interference signals may come from electromagnetic fields, power supply equipment, cables or other electronic equipment. Their frequencies and amplitudes are similar to those of guided wave signals and are difficult to distinguish. Magnetostrictive sensor technology is a technology that uses the magnetostrictive effect to measure physical quantities. The magnetostrictive effect refers to the fact that when ferromagnetic materials are magnetized under the action of a magnetic field, a tiny change in length will occur. This material can be used as a sensor to obtain information about the measured physical quantity by measuring the changes in the magnetostrictive sheet. Ultrasonic guided wave nondestructive testing technology is widely used in various fields due to its advantages such as long distance, large range, and single-ended transmission and reception. Ultrasonic guided wave technology has many advantages: 1. High sensitivity: Guided wave monitoring has high sensitivity and can detect signals in structures far away from the sensor; 2. Wide bandwidth: Guided wave monitoring can monitor over a wide range of frequencies and is suitable for guided wave signals in different frequency bands; 3. Real-time: Guided wave monitoring can record and analyze guided wave signals in real time, detect the health of the structure in time, and effectively prevent accidents; 4. Non-contact long-distance propagation: Guided wave monitoring technology is a non-destructive test. Guided waves can propagate over long distances and over a large range, avoiding the possibility of destructive testing and personal injury, especially for objects with coatings and difficult to access. The single-ended transceiver and long-distance propagation characteristics will have unique detection and monitoring technology advantages. Guided wave technology is widely used in structural health monitoring, such as bridges, buildings, and aircraft. By monitoring and analyzing the propagation characteristics and changes of guided wave signals, the health status, damage or defects of the structure can be detected and evaluated, thereby preventing accidents.

[0003] When encountering electromagnetic noise, traditional magnetostrictive sensors often use filters to try to remove interference signals. However, traditional filters have some disadvantages: 1. Signal distortion: Filters often introduce phase delays and amplitude distortions, resulting in errors in monitoring results; 2. Inability to adapt quickly: Traditional methods require manual adjustment of filter parameters and cannot quickly adapt to different electromagnetic interference environments, reducing real-time and applicability; 3. Increased energy consumption: Traditional filters need to consume additional energy to process interference signals, increasing the energy consumption and maintenance costs of the sensor. Therefore, a new technology is urgently needed to solve the problem of electromagnetic noise pollution and interference of traditional magnetostrictive sensors in long-term guided wave monitoring. This new technology will be able to automatically filter out electromagnetic noise and improve the accuracy and reliability of monitoring results. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide an automatic noise reduction magnetostrictive guided wave monitoring transducer.

[0005] The technical solution adopted by the present invention is:

[0006] The guided wave monitoring transducer includes an electromagnetic noise receiving sensor, a sensor housing, an excitation sensor, an inverter, an adder and a damping spring; the sensor housing is placed on a sample to be tested, the electromagnetic noise receiving sensor, the excitation sensor, the inverter, the adder and the damping spring are all located in the sensor housing, the electromagnetic noise receiving sensor and the excitation sensor are both fixedly connected to the upper surface of the sample to be tested, and damping springs are placed above the electromagnetic noise receiving sensor and the excitation sensor, the excitation sensor is connected to the adder through an inverter, and the electromagnetic noise receiving sensor is connected to the adder through a cable.

[0007] The electromagnetic noise receiving sensor comprises an electromagnetic enameled wire, an electromagnetic backing layer and a cushion layer, wherein the electromagnetic enameled wire is wound around the outer periphery of the electromagnetic backing layer, the electromagnetic backing layer wound with the electromagnetic enameled wire is placed on the cushion layer, and the cushion layer is bonded to the sample to be tested through a waveguide coupling agent; the excitation sensor comprises an excitation enameled wire, an excitation backing layer and a magnetostrictive strip, wherein the excitation enameled wire is wound around the outer periphery of the excitation backing layer, the excitation backing layer wound with the excitation enameled wire is placed on the magnetostrictive strip, the magnetostrictive strip is bonded to the sample to be tested through a waveguide coupling agent, and the electromagnetic noise receiving sensor and the excitation sensor are arranged at intervals.

[0008] The adder comprises an operational amplifier, a first input resistor R1, a second input resistor R2, a balancing resistor R3 and a feedback resistor R f One end of the first input resistor R1 is led out as the first input port of the adder, and one end of the second input resistor R2 is led out as the second input port of the adder. The other ends of the first input resistor R1 and the second input resistor R2 are connected in parallel, and the circuit after the first input resistor R1 and the second input resistor R2 are connected in parallel is respectively connected to the feedback resistor R f One end is connected to an input port of the operational amplifier, and the feedback resistor R f The other end of is connected to the output port of the operational amplifier as the output port of the adder, one end of the balancing resistor R3 is connected to the other input port of the operational amplifier, and the other end of the balancing resistor R3 is grounded.

[0009] Among them, the second input resistor R2 and the feedback resistor R fThe resistance values ​​of the first input resistor R1 and the balancing resistor R3 are fixed. The first input resistor R1 and the balancing resistor R3 are sliding resistors, and their resistance values ​​can be adjusted as needed. The resistance value of the balancing resistor R3 is equal to the first input resistor R1, the second input resistor R2, and the feedback resistor R f And, that is

[0010] R3=1 / ((1 / R1)+(1 / R2)+(1 / R f ))

[0011] Wherein, R1 represents the resistance value of the first input resistor, R2 represents the resistance value of the second input resistor, and R f R represents the resistance value of the feedback resistor, and R3 represents the resistance value of the balancing resistor.

[0012] The transducer is provided with two groups of damping springs, one group of damping springs is placed on the electromagnetic backing layer of the electromagnetic noise receiving sensor, and the other group of damping springs is placed on the excitation backing layer of the excitation sensor, and the sensor housing is placed on the damping springs.

[0013] The excitation sensor is connected to one end of the inverter, the other end of the inverter is connected to the first input port of the adder, the electromagnetic noise receiving sensor is connected to the second input port of the adder, and the output port of the adder is connected to the external waveguide detection device through a cable.

[0014] The resistance value of the balancing resistor R3 is obtained by the following method:

[0015] R3=1 / ((1 / R1)+(1 / R2)+(1 / R f ))

[0016] Wherein, R1 represents the resistance value of the first input resistor, R2 represents the resistance value of the second input resistor, and R f R represents the resistance value of the feedback resistor, and R3 represents the resistance value of the balancing resistor.

[0017] The electromagnetic backing layer and the excitation backing layer are made of non-ferromagnetic material with a thickness of 0.8 mm to 1.2 mm.

[0018] The magnetostrictive strip is made of an iron-cobalt-nickel alloy material with a thickness of 1 mm to 2 mm, and the cushion layer is made of an aluminum alloy material, and the thickness of the cushion layer is consistent with the thickness of the magnetostrictive strip.

[0019] The operational amplifier is an integrated operational amplifier.

[0020] The adder adopts an inverting addition operation circuit.

[0021] Preferably, the inverter is a CMOS inverter composed of two enhancement mode MOS field effect transistors.

[0022] Preferably, the operational amplifier is an integrated operational amplifier.

[0023] Preferably, the excitation sensor and the electromagnetic noise receiving sensor are respectively tightly attached to the sample to be tested via a waveguide coupling agent, thereby improving the efficiency of guided wave acoustic energy conversion.

[0024] Preferably, the waveguide coupling agent is an epoxy coupling agent.

[0025] Preferably, the adder is an inverting addition circuit.

[0026] The present invention realizes effective filtering of electromagnetic noise and amplification of waveguide signals through the corresponding inverters and adders through the cleverly designed excitation sensor and electromagnetic noise receiving sensor, thereby improving the accuracy of waveguide monitoring data, avoiding the influence of interference signals on monitoring results, and making monitoring results more reliable. At the same time, traditional waveguide transducers are easily damaged by interference signals under conditions of poor electromagnetic environment, and their service life is easily shortened. This noise reduction transducer can effectively suppress interference signals and extend the service life of the sensor.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention adopts an inverter to only invert the phase of the electromagnetic noise signal without involving a change in the signal amplitude, which can better remove the electromagnetic noise without affecting the waveguide signal itself, thereby improving the signal-to-noise ratio and stability of the waveguide signal.

[0029] 2. The present invention can not only eliminate electromagnetic noise, but also amplify the waveguide signal by using the inverting addition circuit. The noise reduction transducer can effectively suppress interference signals and extend the service life of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural block diagram of the connection between the magnetostrictive guided wave monitoring transducer and the guided wave detection equipment of the present invention.

[0031] Figure 2 The invention is a block diagram of the installation of the automatic noise reduction magnetostrictive guided wave monitoring transducer and the sample to be tested.

[0032] Figure 3 It is a schematic diagram of the enameled wire of the magnetostrictive guided wave monitoring transducer of the present invention being wound around a backing layer.

[0033] Figure 4 The invention discloses an adder circuit schematic diagram of an automatic noise reduction magnetostrictive waveguide monitoring transducer.

[0034] Figure 5 This is a waveform diagram before noise reduction obtained from an embodiment of the magnetostrictive guided wave monitoring transducer of the present invention.

[0035] Figure 6 This is a waveform diagram after noise reduction obtained from an embodiment of the magnetostrictive guided wave monitoring transducer of the present invention.

[0036] Figure 7 1 is a waveform diagram of the transducer before and after noise reduction obtained in an embodiment of the present invention.

[0037] In the figure: 1-sample to be tested; 2-cushion; 3-electromagnetic noise receiving sensor; 4-sensor housing; 5-excitation sensor; 6-magnetostrictive strip; 7-inverter; 8-adder; 9-guided wave detection equipment; 10-cable; 11-backing layer; 12-enamelled wire; 13-damping spring; 14-operational amplifier; 15-earth. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with specific implementation cases. The following implementation cases will help those skilled in the art to further understand the present invention, but will not limit the present invention in any form.

[0039] like Figure 1 and Figure 2 As shown, the transducer includes an electromagnetic noise receiving sensor 3, a sensor housing 4, an excitation sensor 5, an inverter 7, an adder 8 and a damping spring 13; the sensor housing 4 is placed on the sample to be tested 1, the electromagnetic noise receiving sensor 3, the excitation sensor 5, the inverter 7, the adder 8 and the damping spring 13 are all located in the sensor housing 4, the electromagnetic noise receiving sensor 3 and the excitation sensor 5 are both fixedly connected to the upper surface of the sample to be tested 1, and the damping spring 13 is placed above the electromagnetic noise receiving sensor 3 and the excitation sensor 5, the excitation sensor 5 is connected to the adder 8 through the inverter 7, and the electromagnetic noise receiving sensor 3 is connected to the adder 8 through a cable.

[0040] like Figure 3 As shown, the electromagnetic noise receiving sensor 3 includes an electromagnetic enameled wire, an electromagnetic backing layer and a cushion layer 2, the electromagnetic enameled wire is wound around the outer periphery of the electromagnetic backing layer, the electromagnetic backing layer wound with the electromagnetic enameled wire is placed on the cushion layer 2, and the cushion layer 2 is bonded to the sample 1 to be tested through a waveguide coupling agent; the excitation sensor 5 includes an excitation enameled wire, an excitation backing layer and a magnetostrictive tape 6, the excitation enameled wire is wound around the outer periphery of the excitation backing layer, the excitation backing layer wound with the excitation enameled wire is placed on the magnetostrictive tape 6, the magnetostrictive tape 6 is bonded to the sample 1 to be tested through a waveguide coupling agent, and the electromagnetic noise receiving sensor 3 and the excitation sensor 5 are arranged side by side with an interval, and the electromagnetic noise receiving sensor 3 and the excitation sensor 5 are not in contact with each other.

[0041] The electromagnetic enameled wire and the excitation enameled wire are both enameled wire 12, and the electromagnetic enameled wire and the excitation enameled wire are made of the same material. The electromagnetic backing layer and the excitation backing layer are both backing layer 11, and the electromagnetic backing layer and the excitation backing layer are made of the same material. The electromagnetic noise receiving sensor 3 and the excitation sensor 5 are placed side by side.

[0042] like Figure 4 As shown, the adder 8 includes an operational amplifier 14, a first input resistor R1, a second input resistor R2, a balancing resistor R3 and a feedback resistor R f One end of the first input resistor R1 is led out as the first input port of the adder 8, one end of the second input resistor R2 is led out as the second input port of the adder 8, the other ends of the first input resistor R1 and the second input resistor R2 are connected in parallel, that is, the other end of the first input resistor R1 is connected to the other end of the second input resistor R2, and the circuit after the first input resistor R1 and the second input resistor R2 are connected in parallel is connected to the feedback resistor R through the cable 10. f One end of the feedback resistor R f The other end of the balancing resistor R3 is connected to the output port of the operational amplifier 14 and serves as the output port of the adder 8. One end of the balancing resistor R3 is connected to the other input port of the operational amplifier 14 through the cable 10, and the other end of the balancing resistor R3 is connected to the ground 15.

[0043] Among them, the second input resistor R2 and the feedback resistor R f The resistance values ​​of the first input resistor R1 and the balancing resistor R3 are fixed. The first input resistor R1 and the balancing resistor R3 are sliding resistors, and their resistance values ​​can be adjusted as needed. The resistance value of the balancing resistor R3 is equal to the first input resistor R1, the second input resistor R2, and the feedback resistor R f And, that is

[0044] R3=1 / ((1 / R1)+(1 / R2)+(1 / R f ))

[0045] Wherein, R1 represents the resistance value of the first input resistor, R2 represents the resistance value of the second input resistor, and R f R represents the resistance value of the feedback resistor, and R3 represents the resistance value of the balancing resistor.

[0046] Specifically, the positive input terminal of the operational amplifier 14 is connected to the first input resistor R1, the second input resistor R2 and the feedback resistor R f The negative input terminal of the operational amplifier 14 is connected to the balancing resistor R3.

[0047] Two groups of damping springs 13 are provided in the transducer, one group of damping springs 13 is placed on the electromagnetic backing layer of the electromagnetic noise receiving sensor 3, and the other group of damping springs 13 is placed on the excitation backing layer of the excitation sensor 5. The sensor housing 4 is placed on the damping springs 13 for fixing the waveguide transducer of the present invention.

[0048] In a specific implementation, there are 12 damping springs 13 in total, one group of 6 of which are evenly placed on the electromagnetic noise receiving sensor 3 , and another group of 6 of which are evenly placed on the excitation sensor 5 .

[0049] The excitation sensor 5 is connected to one end of the inverter 7, the other end of the inverter 7 is connected to the first input port of the adder 8, the electromagnetic noise receiving sensor 3 is connected to the second input port of the adder 8, and the output port of the adder 8 is connected to the external waveguide detection device 9 through the cable 10.

[0050] Specifically, the inverter 7 is electrically connected to the first input resistor R1, the electromagnetic noise receiving sensor 3 is electrically connected to the second input resistor R2, and the feedback resistor R f And the operational amplifier 14 are connected to the waveguide detection device 9.

[0051] The resistance value of the balancing resistor R3 is obtained by the following method:

[0052] R3=1 / ((1 / R1)+(1 / R2)+(1 / R f ))

[0053] Wherein, R1 represents the resistance value of the first input resistor, R2 represents the resistance value of the second input resistor, and R f R represents the resistance value of the feedback resistor, and R3 represents the resistance value of the balancing resistor.

[0054] The electromagnetic backing layer and the excitation backing layer are made of non-ferromagnetic material with a thickness of 0.8 mm to 1.2 mm.

[0055] The magnetostrictive strip 6 is made of an iron-cobalt-nickel alloy material with a thickness of 1 mm to 2 mm, and the material is a flexible thin sheet structure. The cushion layer 2 is made of an aluminum alloy material, and the thickness of the cushion layer 2 is consistent with the thickness of the magnetostrictive strip 6 .

[0056] The operational amplifier 14 is an integrated operational amplifier, and the adder is an inverting addition circuit.

[0057] Assume that the output signals of the excitation sensor and the electromagnetic noise receiving sensor are Ps and Pn respectively, where Ps = S1 + noise, Pn = noise, where S1 is the waveguide signal and noise is the electromagnetic noise signal; Figure 1 As shown, the signal obtained after passing through the inverter 7 is set to Pf=-Ps=-(S1+noise).

[0058] Further, by Figure 4 It is known that the output signal of adder 8 is set to Pj, and the expression of the output signal Pj is as follows:

[0059] Pj=-((R f / R1)×Pf+(R f / R2)×Pn)=-((R f / R1)×(-(S1+noise))+(R f / R2)×noise)

[0060] It can be seen that we only need to adjust the sliding rheostat R1 so that the input resistance R1 is equal to the input resistance R2, and set R1=R2=R, then the above formula can be rearranged as:

[0061] Pj=-((R f / R1)×(-(S1+noise))+(R f / R2)×noise)=(R f / R)×S1

[0062] It can be seen that the electromagnetic noise signal noise is eliminated, while the waveguide signal S1 is retained and the amplification R is realized. f / R times.

[0063] Therefore, as a beneficial effect, the present invention can not only eliminate electromagnetic noise, but also achieve different multiples of amplification of the waveguide signal.

[0064] During operation, this embodiment uses a switch point rail as the object to be measured, which is about 22 meters long. The waveguide working mode is a single-transmit single-receive mode. The transducer proposed in the present invention is used as a receiving sensor in the waveguide single-transmit single-receive mode. First, according to Figure 1 As shown, the detection equipment is connected; secondly, in the absence of a waveguide excitation signal, the output of the adder 8 is made zero by adjusting the sliding rheostat (i.e., the input resistor R1), and then the sliding rheostat-balancing resistor R3 is adjusted so that the resistance value of the balancing resistor R3 is equal to the first input resistor R1, the second input resistor R2, and the feedback resistor R f And, that is

[0065] R3=1 / ((1 / R1)+(1 / R2)+(1 / R f ))

[0066] Wherein, R1 represents the resistance value of the first input resistor, R2 represents the resistance value of the second input resistor, and R f R represents the resistance value of the feedback resistor, and R3 represents the resistance value of the balancing resistor.

[0067] Again, in the single-transmit and single-receive mode, the waveguide excitation signal is loaded, and the received waveguide signal is as follows Figure 6 The red waveform in (i.e., the signal after noise reduction); again, the inverter 7 is removed, that is, no inversion processing is performed, so the electromagnetic noise signal with the same phase received by the excitation sensor and the electromagnetic noise receiving sensor is then added by the adder. Since the phases are the same, the electromagnetic noise signal will not cancel out; again, the waveguide signal is excited, and the received signal is as follows Figure 5 The blue waveform in (i.e. the signal before noise reduction) is shown in Figure 2. Figure 5 and Figure 6 Put together and show, Figure 7 As shown in the figure, the waveforms before and after noise reduction show that the design structure of the present invention with noise reduction function can well filter out electromagnetic noise in the environment and improve the signal-to-noise ratio of the waveguide signal. In actual long-term monitoring of waveguides, it has important engineering application value and significance for ensuring the stability and signal-to-noise ratio of the waveguide signal.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic noise reduction magnetostrictive guided wave monitoring transducer, characterized in that: The invention comprises an electromagnetic noise receiving sensor (3), a sensor housing (4), an excitation sensor (5), an inverter (7), an adder (8) and a damping spring (13); the sensor housing (4) is placed on a sample to be tested (1); the electromagnetic noise receiving sensor (3), the excitation sensor (5), the inverter (7), the adder (8) and the damping spring (13) are all located in the sensor housing (4); the electromagnetic noise receiving sensor (3) and the excitation sensor (5) are both fixedly connected to the upper surface of the sample to be tested (1); a damping spring (13) is placed above the electromagnetic noise receiving sensor (3) and the excitation sensor (5); the excitation sensor (5) is connected to the adder (8) via the inverter (7); and the electromagnetic noise receiving sensor (3) is connected to the adder (8) via a cable.

2. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 1, characterized in that: The electromagnetic noise receiving sensor (3) comprises an electromagnetic enameled wire, an electromagnetic backing layer and a cushion layer (2), wherein the electromagnetic enameled wire is wound around the outer periphery of the electromagnetic backing layer, the electromagnetic backing layer wound with the electromagnetic enameled wire is placed on the cushion layer (2), and the cushion layer (2) is bonded to the sample to be tested (1); the excitation sensor (5) comprises an excitation enameled wire, an excitation backing layer and a magnetostrictive strip (6), wherein the excitation enameled wire is wound around the outer periphery of the excitation backing layer, the excitation backing layer wound with the excitation enameled wire is placed on the magnetostrictive strip (6), the magnetostrictive strip (6) is bonded to the sample to be tested (1), and the electromagnetic noise receiving sensor (3) and the excitation sensor (5) are arranged with an interval between them.

3. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 1, characterized in that: The adder (8) comprises an operational amplifier (14), a first input resistor R1, a second input resistor R2, a balancing resistor R3 and a feedback resistor R f One end of the first input resistor R1 is led out as the first input port of the adder (8), one end of the second input resistor R2 is led out as the second input port of the adder (8), the other ends of the first input resistor R1 and the second input resistor R2 are connected in parallel, and the circuit after the first input resistor R1 and the second input resistor R2 are connected in parallel is respectively connected to the feedback resistor R f One end of the feedback resistor R is connected to an input port of the operational amplifier (14). f The other end of the balancing resistor R3 is connected to the output port of the operational amplifier (14) and serves as the output port of the adder (8). One end of the balancing resistor R3 is connected to the other input port of the operational amplifier (14), and the other end of the balancing resistor R3 is grounded.

4. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 2, characterized in that: Two groups of damping springs (13) are arranged in the transducer, one group of damping springs (13) is placed on the electromagnetic backing layer of the electromagnetic noise receiving sensor (3), and the other group of damping springs (13) is placed on the excitation backing layer of the excitation sensor (5), and the sensor housing (4) is placed on the damping springs (13).

5. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 3 is characterized in that: The excitation sensor (5) is connected to one end of an inverter (7), the other end of the inverter (7) is connected to a first input port of an adder (8), the electromagnetic noise receiving sensor (3) is connected to a second input port of the adder (8), and the output port of the adder (8) is externally connected to a waveguide detection device (9) via a cable (10).

6. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 3, characterized in that: The resistance value of the balancing resistor R3 is obtained by the following method: R3=1 / ((1 / R1)+(1 / R2)+(1 / R f )) Wherein, R1 represents the resistance value of the first input resistor, R2 represents the resistance value of the second input resistor, and R f R represents the resistance value of the feedback resistor, and R3 represents the resistance value of the balancing resistor.

7. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 2, characterized in that: The electromagnetic backing layer and the excitation backing layer are made of non-ferromagnetic material with a thickness of 0.8 mm to 1.2 mm.

8. The automatic noise reduction magnetostrictive guided wave monitoring transducer according to claim 2, characterized in that: The magnetostrictive strip (6) is made of an iron-cobalt-nickel alloy material with a thickness of 1 mm to 2 mm, and the cushion layer (2) is made of an aluminum alloy material. The thickness of the cushion layer (2) is consistent with the thickness of the magnetostrictive strip (6).

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