CN114295258A

CN114295258A - Electromagnetic composite nondestructive detection sensor, system and method

Info

Publication number: CN114295258A
Application number: CN202111653957.2A
Authority: CN
Inventors: 高斌; 刘乾杭
Original assignee: Sichuan Mudisheng Technology Co ltd
Current assignee: Sichuan Mudisheng Technology Co ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-04-08

Abstract

The invention discloses an electromagnetic composite nondestructive detection sensor, system and method, belonging to the technical field of nondestructive detection and comprising an excitation component and a receiving component; the excitation assembly includes a first excitation coil that receives a very low frequency excitation signal, a low frequency excitation signal, or a mid or high frequency excitation signal, and a second excitation coil that receives a mid or low frequency excitation signal or a high frequency excitation signal. The exciting assembly and the receiving assembly which work based on exciting signals with different frequencies are integrated in the same sensor, different nondestructive tests including eddy current test, alternating current magnetic field test, magnetic Barkhausen noise test, incremental permeability test and the like are realized by introducing different exciting signals to the first exciting coil and the second exciting coil at different moments, and further stress change caused by microstructures, the influence of incremental permeability on stress and the influence of conductivity and permeability on stress can be obtained, so that the stress size of a component can be accurately judged, and an experimental verification basis is provided for complex stress theory research.

Description

Electromagnetic composite nondestructive detection sensor, system and method

Technical Field

The invention relates to the technical field of nondestructive testing, in particular to an electromagnetic composite nondestructive testing sensor, system and method.

Background

Ferromagnetic materials are widely used in aerospace, automotive and steamship, high-speed rail bridges and daily life. However, during the service life of the components, with the increase of service time and external environmental and human factors such as impact, corrosion and the like, stress concentration and fatigue are caused, so that cracks occur, and then catastrophic accidents are caused. In order to solve the problems, the service state of the component in service needs to be monitored in real time, and the nondestructive testing method is well applied to industrial structure health monitoring.

The existing nondestructive testing method for the stress of the ferromagnetic material generally comprises an ultrasonic testing method, an X-ray method, a magnetic Barkhausen noise method and the like. However, the ultrasonic detection method requires a coupling agent for detection; the use scene of the X-ray method is limited; the magnetic Barkhausen noise method has a plurality of stress influence factors such as magnetic permeability, electric conductivity, microstructure, lattice state, dislocation density and the like, and a single nondestructive testing method is not enough to completely extract complete stress information, namely, the service state of a service component cannot be accurately tested. Further, how to integrate multiple non-destructive testing methods into a sensor and achieve accurate stress testing presents new challenges to the structural design of the sensor.

Disclosure of Invention

The invention aims to solve the problem of low detection accuracy caused by the fact that complete stress information of a component cannot be completely extracted in the prior art, and provides an electromagnetic composite nondestructive detection sensor, system and method.

The purpose of the invention is realized by the following technical scheme: an electromagnetic composite nondestructive inspection sensor includes an excitation component and a receiving component; the excitation assembly comprises a first excitation coil for receiving an extremely low frequency excitation signal, a low frequency excitation signal or a medium and high frequency excitation signal, and a second excitation coil for receiving the medium and low frequency excitation signal or the high frequency excitation signal; the receiving assembly comprises a magnetic head for receiving longitudinal electromagnetic signals, a magnetic induction intensity detector and a first receiving coil for receiving transverse electromagnetic signals;

the sensor also comprises a first magnetic yoke for magnetic gathering; the first excitation coil is wound on the first magnetic yoke; the magnetic head is arranged close to the first magnetic yoke; the magnetic field signal receiver is arranged on the side surface of the magnetic head; the second excitation coil is wound on the magnetic head; the first receiving coil is arranged on the side surface of the magnetic head.

In one example, the first yoke is a "U" shaped yoke.

In one example, the magnetic head comprises a shielding shell, wherein the bottom of the shell is provided with a micron-scale slit; and a second magnet yoke is arranged in the shell, and a second receiving coil is wound on the second magnet yoke.

In one example, the magnetic induction detector is a hall sensor.

In one example, the first receiving coil is a multilayer coaxial PCB coil, and the layers of PCB coils are reversely wound and connected in series.

In one example, the sensor further comprises a pre-processing circuit for filtering and amplifying, the pre-processing circuit being connected to the magnetic head and/or the magnetic field signal receiver and/or the first receiving coil and/or the excitation coil.

In one example, the receiving assembly, the second exciting coil and the preprocessing circuit are arranged on a PCB circuit board, and the receiving assembly is arranged in the center of the first magnetic yoke.

It should be further noted that the technical features corresponding to the above-mentioned examples of the sensor may be combined with each other or replaced to form a new technical solution.

The invention further comprises an electromagnetic composite nondestructive testing system, which comprises the sensor formed by combining any one or more of the above examples, an excitation source and a data processing unit, wherein the excitation source is connected with an excitation coil; the data processing unit is connected with the magnetic head, the magnetic field signal receiver and the first receiving coil.

The invention also comprises an electromagnetic composite nondestructive testing method, which is applied based on the sensor formed by any one or combination of the examples, and specifically comprises the following steps:

introducing a high-frequency alternating current signal to the second excitation coil for eddy current detection;

introducing a medium-high frequency alternating current signal to the first exciting coil for alternating current electromagnetic field detection;

introducing a very low frequency alternating current signal to the first exciting coil for magnetic Barkhausen noise detection;

introducing a very low frequency alternating current signal to the first exciting coil, and introducing a medium-low frequency alternating current signal to the second exciting coil for incremental magnetic permeability detection;

performing any two or more of the electromagnetic detections described above;

any two or more of the electromagnetic detections described above are performed.

In an example, the method further comprises:

and receiving the detection signal according to the magnetic head and/or the first receiving coil, and determining the stress of the component according to the amplitude change of the detection signal.

It should be further noted that the technical features corresponding to the above-mentioned detection methods can be combined with each other or replaced to form a new technical solution.

Compared with the prior art, the invention has the beneficial effects that:

1. in one example, an excitation assembly and a receiving assembly which work based on excitation signals of different frequencies are integrated in the same sensor, different nondestructive detections are realized by introducing different excitation signals to a first excitation coil and a second excitation coil at different moments, the nondestructive detections comprise eddy current detection, alternating current electromagnetic field detection, magnetic Barkhausen noise detection, incremental permeability detection and the like, and further stress change caused by microstructures, the influence of the incremental permeability on stress and the influence of conductivity and permeability on stress can be acquired, so that the stress of a component can be accurately judged, and an experimental verification basis is provided for complex stress theory research.

2. In one example, the magnetic yoke is used for enhancing the excited magnetic field so as to locally magnetize the tested piece, and the magnetized area of the U-shaped magnetic yoke is easy to position, small in processing difficulty and low in cost.

3. In one example, the magnetic field signal outside the gap of the magnetic head shielding shell is shielded by the shielding shell, and only the electromagnetic signal at the gap is allowed to pass through, so that the influence of clutter signals on the detection signal received by the second receiving coil is avoided, and the magnetic head with high spatial resolution can be obtained, can measure the information at the magnetic domain wall, and has the capability of measuring the stress of the micro-object.

4. In one example, the hall sensor has high sensitivity for accurately detecting magnetic induction.

5. In one example, the multi-layer coaxial series connection receiving coil can improve the detection sensitivity, simultaneously reduce the optimal detection frequency and effectively reduce the requirement on the excitation signal.

6. In one example, the pre-processing circuit is used for preprocessing the excitation signal or the received detection signal, such as filtering and amplifying, so that electromagnetic interference can be reduced, and detection accuracy can be improved.

7. In one example, the receiving assembly is located in the center of the first magnetic yoke, so that the signal transmission quality can be ensured, the energy transmission efficiency can be improved to the maximum extent, and the optimal detection effect can be achieved.

8. In one example, excitation signals with different frequencies are introduced into the two excitation coils, so that multiple nondestructive detections can be realized through a single sensor, the stress of the tested piece can be comprehensively judged according to multiple detection modes, and the stress detection accuracy of the tested piece is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention.

FIG. 1 is a schematic diagram of a sensor configuration in accordance with an example of the present invention;

FIG. 2(a) is a front view of a first magnetic yoke in an example of the invention;

FIG. 2(b) is a side view of a first magnetic yoke in an example of the invention;

FIG. 2(c) is a top view of a first magnetic yoke in an example of the invention;

FIG. 3(a) is a front view of a first excitation coil in one example of the invention;

FIG. 3(b) is a side view of a first excitation coil in an example of the invention;

FIG. 3(c) is a top view of a first excitation coil in an example of the invention;

FIG. 4(a) is a front view of the external structure of a magnetic head according to an example of the present invention;

FIG. 4(b) is a side view of an outer structure of a magnetic head in an example of the present invention;

FIG. 4(c) is a bottom view of an external structure of a magnetic head according to an example of the present invention;

FIG. 5 is a schematic view of the internal structure of a magnetic head in an example of the present invention;

FIG. 6 is a schematic diagram of a first receive coil in one example of the invention;

FIG. 7(a) is a front view of a second excitation coil in one example of the invention;

FIG. 7(b) is a side view of a second excitation coil in an example of the invention;

FIG. 7(c) is a top view of a second excitation coil in an example of the invention;

FIG. 8 is a circuit schematic of a pre-processing circuit in one example of the invention;

FIG. 9 is a schematic diagram of an electromagnetic composite nondestructive inspection system in one example of the invention;

FIG. 10 is a flow chart of a method of electromagnetic composite nondestructive testing in an example of the invention;

FIG. 11 is a schematic illustration of excitation set-up patterns in an example of the invention;

FIG. 12 is a graph illustrating eddy current test results in an example of the present invention;

FIG. 13 is a graph illustrating the results of an electromagnetic field test using an AC current in accordance with an example of the present invention;

FIG. 14 is a graph illustrating a magnetic Barkhausen noise method detection result according to an example of the present invention;

FIG. 15 is a graph illustrating incremental permeability measurements in an example of the present invention.

In the figure: the test device comprises a first excitation coil 11, a second excitation coil 12, a magnetic head 21, a second magnetic yoke 211, a second receiving coil 212, a slit 213, a magnetic induction detector 22, a first receiving coil 23, a through hole 231, a first magnetic yoke 3, a preprocessing circuit 4 and a tested piece 5.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that directions or positional relationships indicated by "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like are directions or positional relationships described based on the drawings, and are only for convenience of description and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In one example, an electromagnetic composite nondestructive testing sensor, as shown in FIG. 1, specifically includes an excitation assembly and a receiving assembly; the excitation assembly comprises a first excitation coil 11 for receiving an extremely-low frequency excitation signal, a low frequency excitation signal or a medium-high frequency excitation signal, and a second excitation coil 12 for receiving a medium-low frequency excitation signal or a high-frequency excitation signal, wherein the excitation signals are all alternating current signals; the receiving assembly comprises a magnetic head 21 for receiving the longitudinal electromagnetic signal, a magnetic induction detector 22 and a first receiving coil 23 for receiving the transverse electromagnetic signal, namely, the magnetic head 21 and the first receiving coil 23 are used for receiving a detection signal (electromagnetic signal) carrying deformation information (stress change information) of the tested piece 5. It should be noted that the low frequency, the medium-high frequency, the medium-low frequency and the high frequency referred to in the present application follow the definition of the wave frequency band in the communication field, i.e. the range of the extremely low frequency band is 3Hz to 30 Hz; the low-frequency range is 30 Hz-150 Hz; the range of the medium and low frequency ranges from 150Hz to 500 Hz; the range of the middle and high frequency ranges is 500 Hz-5 KHz; the high frequency range is 5K-16 KHz.

Further, preferably, a low-amplitude high-frequency signal of the second excitation coil 12 is given first, and then eddy current detection is performed on the tested piece 5; then, giving a high-amplitude medium-high frequency signal of the first exciting coil 11, and further carrying out alternating current electromagnetic field detection on the tested piece 5; then, a high-amplitude extremely-low-frequency signal of the first exciting coil 11 is given, and magnetic Barkhausen noise detection is carried out on the tested piece 5; and finally, giving a high-amplitude extremely-low-frequency signal of the first exciting coil 11, and simultaneously giving a low-amplitude medium-low-frequency signal of the second exciting coil 12, so as to detect the incremental permeability of the tested piece 5.

Further, the sensor further comprises a first magnetic yoke 3 for magnetic concentration; the first excitation coil 11 is wound on the first magnetic yoke 3; the magnetic head 21 is arranged close to the first yoke 3, so as to receive electromagnetic signals; the magnetic field signal receiver is arranged on one side of the magnetic head 21; the second exciting coil 12 is wound on the magnetic head 21; the first receiving coil 23 is provided on the other side of the magnetic head 21, and preferably, the first receiving coil 23 and the magnetic field signal receiver are symmetrically provided on both sides of the magnetic head 21.

When a high-frequency alternating current (high-frequency excitation signal) is applied to the second excitation coil 12 above the tested object 5, an eddy current is formed on the tested object 5, and feedback information of the eddy current can be received through the magnetic head 21 and/or the first receiving coil 23, so that eddy current detection is realized for researching the influence of the electric conductivity on the stress.

When alternating current (medium-high frequency excitation signal) with frequency above kilohertz is introduced into the first excitation coil 11, a uniform electric field is formed on the surface of the tested piece 5, the electric field signal is received by the magnetic head 21 and/or the first receiving coil 23, and therefore alternating current electromagnetic field detection is achieved and is used for researching the influence of electric conductivity and magnetic conductivity on stress.

When the first exciting coil 11 wound on the first magnetic yoke 3 is fed with the extremely low frequency alternating current, a changing magnetic field is generated at the moment, the first magnetic yoke 3 further enhances the magnetic field to generate a larger magnetic field, the tested piece 5 (component) to be tested can be locally magnetized, a series of electromagnetic pulse noises can be generated in the process, the noises can be received by the magnetic head 21 and/or the first receiving coil 23 and fed back in a voltage form, and then the magnetic Barkhausen noise detection is realized for searching stress changes caused by the microstructure.

On the basis that the tested piece 5 is magnetized, namely, a very low frequency excitation signal is correspondingly applied to the first excitation coil 11, and a medium and low frequency excitation signal is applied to the second excitation coil 12 above the tested piece 5, at the moment, a superposed magnetic field is formed at the tested piece 5, so that small magnetic hysteresis loops appear on a magnetic hysteresis loop appearing in the original magnetization process, and the increment can be detected through the magnetic head 21 and/or the first receiving coil 23, so that incremental magnetic permeability detection is realized and is used for researching the influence of the incremental magnetic permeability on stress.

The existing single detection mode such as eddy current detection has low stress detection accuracy on the tested piece 5 because a detection signal is sensitive to various influence factors except stress, such as the influence of uneven materials, plastic deformation and the like of residual stress, inclusion and the like. In this example, the excitation coils working based on excitation signals of different frequencies and the receiving component are integrated in the same sensor, different nondestructive detections are realized by introducing the excitation signals of different frequencies to the first excitation coil 11 and/or the second excitation coil 12 at different times, including eddy current detection, ac electromagnetic field detection, magnetic barkhausen noise detection, incremental permeability detection, and the like, when the stress of the test point of the tested piece 5 is different, the amplitude, the phase, the frequency band, and the like of the signal received by the magnetic head 21 or the first receiving coil 23 will change, and such changes include the change information of the stress, in this application, by controlling the detection timing, that is, introducing the excitation signals of different frequencies to the first excitation coil 11 and/or the second excitation coil 12 at different times, different nondestructive detections are realized, and signal characteristic extraction and fusion are carried out, so that the stress change caused by the microstructure, the influence of the incremental magnetic conductivity on the stress and the influence of the electric conductivity and the magnetic conductivity on the stress can be obtained, the stress state of the tested piece 5 is judged from multiple aspects, and the influence of factors such as material unevenness and plasticity is separated, so that the accuracy of stress evaluation is improved, and an experimental verification basis is provided for complex stress theory research.

In one example, as shown in fig. 2, the first yoke 3 is a "U" shaped yoke. Specifically, the magnetic yoke is stamped and laminated by a silicon steel sheet. The excited magnetic field can be enhanced to locally magnetize the tested piece 5, compared with ferrite, the magnetic yoke punched and laminated by silicon steel sheets can be freely processed in shape, the magnetic induction intensity is high in saturation, and the cost is low; the magnetization area of the U-shaped magnetic yoke is between two legs of the U-shaped magnetic yoke, and the magnetization area is easy to position.

In an example, as shown in fig. 3, the first excitation coil 11 is wound by a copper wire, specifically, is a hollow rectangular parallelepiped coil wound on the transverse section of the first magnetic yoke 3, and preferably, the first excitation coil 11 is wound at the center of the transverse section of the magnetic yoke for generating magnetic field and excitation by an alternating current electromagnetic field method, so that nondestructive electromagnetic detection in different modes can be realized according to different signal frequencies of an excitation source; more specifically, a lead is respectively led out from the head end and the tail end of the first excitation coil 11, and the lead is directly welded to the signal preprocessing circuit PCB and serves as an external excitation input port, that is, the excitation source output end is connected with the excitation input port.

In one example, as shown in fig. 4, the magnetic head 21 is externally provided with a shielding shell, and the bottom of the shell is provided with a micron-scale slit 213; a second yoke 211 is arranged in the housing, and a second receiving coil 212 is wound on the second yoke 211. Specifically, as shown in fig. 5, the second yoke 211 is a "U" shaped yoke, on which a second receiving coil 212 made of copper material is wound, for receiving a longitudinal detection signal of the test piece 5. When the magnetic head 21 receives an electromagnetic signal, a magnetic field outside a gap under the shield case is shielded by the shield case and cannot influence the internal signal reception, so that the magnetic head 21 with high spatial resolution can be obtained, information at a magnetic domain wall can be measured, and the capability of measuring the stress of a micro object is achieved.

In one example, the magnetic induction detector 22 is a Hall sensor SS496A1, has a magnetic field measurement range of +/-840 Gauss and a sensitivity of 2.500mV/Gauss, and is used for receiving a magnetic signal in a direction parallel to the piece 5 to be tested so as to detect the magnetic induction of the magnetic field. As an option, the hall sensor is also used to detect a leakage magnetic signal. More specifically, the three data pins of the hall sensor are connected to the pre-processing circuit 4.

In one example, as shown in fig. 6, the first receiving coil 23 is a multi-layer coaxial PCB coil, and each layer of the PCB coil is reversely wound and connected in series. Specifically, the first receiving coil 23 in this example is a 4-layer coaxial PCB coil for receiving signals in the transverse axis direction of the tested piece 5; the coils between the layers are connected in series through the through hole 231, and the winding direction of each layer of coils is opposite to that of the coil (adjacent to) on the previous layer. More specifically, welding points are reserved at the head end and the tail end of the PCB coil and are connected with the preprocessing circuit 4. In this example, the multi-layer coaxial series-connected receiving coils can improve the detection sensitivity, reduce the optimal detection frequency, and effectively reduce the requirement on the excitation signal.

In one example, as shown in fig. 7, the second excitation coil 12 is wound around the body of the magnetic head 21, and preferably, the second excitation coil 12 is wound around the magnetic head 21, the hall sensor and the first receiving coil 23 on both sides of the magnetic head 21, that is, the second excitation coil 12 is wound around the magnetic head 21, the hall sensor and the first receiving coil 23 to generate eddy current excitation and can be used as one of the excitations of increasing magnetic permeability.

In one example, the electromagnetic composite nondestructive testing sensor further comprises a pre-processing circuit 4 for filtering and amplifying, in this example, the pre-processing circuit 4 is connected with the receiving component, and of course, as an option, the excitation source can be connected with the excitation component through the pre-processing circuit 4 (signal preprocessing circuit). Specifically, as shown in fig. 8, the pre-processing circuit 4 includes a 0.01Hz high-pass filter circuit, an operational amplifier circuit constructed based on an INA849 operational amplifier chip, and a 1MHz low-pass passive filter circuit, which are connected in sequence. More specifically, the pre-processing circuit 4 further includes a front-end data interface, which is connected to the output end of the receiving component through the data interface; the front-end processing circuit 4 also comprises a rear-end aerial plug interface which is connected with the rear-end data processing unit through the aerial plug interface; the pre-processing circuit 4 further includes a level conversion circuit for implementing voltage conversion and providing corresponding operating voltages for the circuits. In this example, the detection signals containing the deformation information of the tested piece 5 received by the receiving components, i.e. the second receiving coil 212, the hall sensor and the first receiving coil 23 in the magnetic head 21, are all preprocessed by the pre-processing circuit 4, such as filtering and amplifying, and then are further input to the back-end data processing unit for data analysis to obtain the stress information of the tested piece 5, so as to increase the signal-to-noise ratio of the signals, reduce the electromagnetic interference and improve the detection accuracy.

In one example, the receiving assembly, the second exciting coil 12 and the pre-processing circuit 4 are arranged on a PCB circuit board, and the receiving assembly is arranged at the center of the first magnetic yoke 3. Specifically, the receiving assembly is located in the center of the first magnetic yoke 3, so that the signal transmission quality can be guaranteed, the energy transmission efficiency is improved to the maximum extent, and the optimal detection effect is achieved. More specifically, the electromagnetic composite nondestructive detection sensor further comprises a fixing base, the base is preferably a U-shaped base with two legs of unequal height, the base is preferably made of resin, a first magnetic yoke 3 is mounted on one leg of the base, a PCB (printed circuit board) is mounted in a gap between the two legs of the first magnetic yoke 3, the other end of the PCB is fixed through the other leg of the base, namely the PCB penetrates through the whole base, the integrated installation of the sensor is realized, and the occupied size is small; the excitation assembly is integrated with the detection assembly, so that detection is facilitated.

The invention also comprises an electromagnetic composite nondestructive testing system which has the same inventive concept as the electromagnetic composite nondestructive testing sensor, the system comprises the sensor formed by combining any one or more of the above examples, as shown in fig. 9, and further comprises an excitation source and a data processing unit, the excitation source is connected with the excitation assembly, and the data processing unit is connected with the receiving assembly. The excitation source is an alternating current signal source, and is specifically a signal generator. The data processing unit comprises a data preprocessing module and a data processing center which are connected in a bidirectional mode, wherein the data preprocessing module is an FPGA (field programmable gate array) and is used for preprocessing data of the electromagnetic detection signals; the data processing center is an industrial Personal Computer (PC) and is used for analyzing the electromagnetic detection signals and further accurately acquiring the stress information of the tested piece 5.

In an example, the system further comprises a signal preprocessing circuit and a preprocessing circuit 4, both of which are used for preprocessing such as signal filtering and amplification, the excitation source is connected with the excitation assembly (the first excitation coil 11 and the second excitation coil 12) through the signal preprocessing circuit, and the receiving assembly (the magnetic head 21, the first receiving coil 23 and the hall sensor) is connected with the data processing unit at the rear end through the preprocessing circuit 4.

The invention also includes an electromagnetic composite nondestructive testing method, which has the same inventive concept as the electromagnetic composite nondestructive testing sensor, and is applied to a sensor formed by combining any one or more of the above examples, as shown in fig. 10, and specifically includes the following steps:

s1: introducing a high-frequency alternating current signal to the second excitation coil for eddy current detection;

s2: introducing a medium-high frequency alternating current signal to the first exciting coil for alternating current electromagnetic field detection;

s3: introducing a very low frequency alternating current signal to the first exciting coil for magnetic Barkhausen noise detection;

s4: and introducing a very low frequency alternating current signal into the first excitation coil, and introducing a medium-low frequency alternating current signal into the second excitation coil for incremental magnetic permeability detection.

The method comprises the steps of controlling a detection time sequence, namely sequentially carrying out eddy current detection, alternating current electromagnetic field detection, magnetic Barkhausen noise detection and incremental permeability detection, so that the amplitude of an excitation signal is increased from small (or increased from small to constant), a tested piece 5 is always kept in an initial magnetization state, the amplitudes of the excitation signals on two excitation coils are always smaller than the amplitudes of detection signals, and then the detection time sequence is controlled to be matched with a detection mode of stress optimal sensitivity at a specific excitation working point, on the basis, corresponding detection signals are extracted based on different detection methods, different detection signal characteristics have different sensitivities to stress and material nonuniformity, therefore, a data processing method based on multi-parameter characteristic selection and extraction is adopted on the basis of the optimal stress sensitivity detection time sequence, the influences of factors such as stress, material nonuniformity and the like on the detection signals can be separated, thereby improving the accuracy of stress assessment.

Specifically, the sensor of the present application is close to the surface of the tested piece 5, as shown in fig. 11, the excitation signal model given by the electromagnetic composite nondestructive testing method in this example is specifically as follows:

firstly, giving an excitation signal of 1Vpp and 30KHz of a second excitation coil 12 (corresponding to excitation 2) to realize eddy current detection (EC); then, alternating current electromagnetic field detection (ACFM) is carried out, and 10Vpp and 1kHz excitation signals are applied to the first excitation coil 11; then, a first exciting coil 11 (corresponding to an exciting coil 1) is given, a 10Vpp and 10Hz sine exciting signal is excited, and magnetic Barkhausen noise detection (MBN) is carried out on the tested piece 5; finally, incremental permeability detection (Sig) is performed, and a 10 Vpp/10 Hz sinusoidal signal is applied to the first excitation coil 11, and a 0.5 Vpp/500 Hz excitation signal is applied to the second excitation coil 12. In the excitation process, the tested piece 5 is in a stretched state, and the 4 methods are carried out on the premise of not changing the measurement position, so that the reliability can be ensured. In each excitation time interval, the nondestructive testing methods produce different electromagnetic effects on the tested piece 5, and the different testing methods are distinguished by the different electromagnetic effects.

In an example, the method further comprises:

the magnetic head 21 and the first receiving coil 23 receive the detection signal, and the stress of the member is determined according to the amplitude change of the detection signal. In this example, excitation signals with different frequencies are introduced into the two excitation coils, so that multiple nondestructive detections can be realized through a single sensor, that is, the stress applied to the tested piece 5 is analyzed by different constituent factors respectively influencing the stress through an eddy current method, an alternating current electromagnetic field method, a magnetic barkhausen noise method and an incremental permeability method, the magnitude of the stress of the tested piece 5 is comprehensively judged, and the accuracy of stress detection of the tested piece 5 is further improved.

Specifically, when the eddy current detection is performed at the first stage corresponding to step S1, given corresponding excitation, an eddy current is generated on the surface of the tested piece 5, and when the electrical conductivity of the tested piece 5 is changed by a tensile force, the size of the eddy current is changed, and the magnetic head 21 receives the change, feeds back the change in the form of voltage, and obtains the eddy current change through the amplitude of the change to determine the size of the stress.

Further, when the ac electromagnetic field is detected in the second stage corresponding to step S2, a corresponding excitation is given, and at this time, a uniform electric field is generated on the tested object 5, the electric field changes in magnitude with the change in the electric conductivity of the tested object 5, and has a certain amount of magnetic information, and the electric conductivity and the magnetic conductivity change with time due to the tensile stress, so that the magnetic head 21 and the first receiving coil 23 can receive the change in the electric conductivity and the magnetic conductivity during this process, and the magnitude of the tensile stress is determined by extracting the average peak value thereof through data processing.

Further, in the step three corresponding to step S3, when performing magnetic barkhausen noise method detection, given excitation can magnetize the test piece 5, and the dynamic behavior of the magnetic domain and domain wall inside the test piece 5 will be captured by the magnetic head 21; meanwhile, the first receiving coil 23 and the hall sensor receive transverse electromagnetic signals, and the results of the two can be verified and compared with each other. Through data processing, the root mean square value of the detection signal received by the magnetic head 21 is extracted to determine the magnitude of the tensile stress at the moment, and a specific calculation formula is as follows:

wherein, X_rmsThe root mean square of the detection signal is expressed and is in direct proportion to the stress; x_iRepresenting a received detection signal sequence; n represents the number of detected signals as a summation upper bound; i represents the ordinal number of the detected signal; σ represents the stress of the test piece 5.

Further, when the incremental permeability detection is performed at the stage four corresponding to the step S4, corresponding excitation is given, the high-frequency eddy current is added to the tested piece 5 for superposition on the basis of magnetization, the superposed field intensity will be different according to the difference of the permeability of the tested piece 5, and the magnetic head 21 receives the field intensity change, and the field intensity change can be obtained by drawing a butterfly diagram, so as to obtain the stress change.

In order to better illustrate the technical effects of the invention, the multi-nondestructive testing method based on the high spatial resolution magnetic head 21 is utilized to fuse the sensor to carry out a stretching experiment on the silicon steel sheet, the given excitation mode refers to the excitation signal parameters in the electromagnetic composite nondestructive testing method, and the stretching forces are respectively 0N, 300N, 600N, 900N, 1200N and 1500N. The results of each method measured at each tensile stress are shown in the figure, with the abscissa of the figure representing the tensile force and the ordinate representing the amplitude of the test signal. Fig. 13 is a graph of a detection result of the ac electromagnetic field method, and it can be seen that as the tensile stress increases, the signal amplitude decreases, and compared with the graph of the eddy current detection result of fig. 12, the ac electromagnetic field detection does not have a tendency of first decreasing and then increasing, both of which are that the tensile stress mainly affects the electrical conductivity of the tested piece 5, however, the ac electromagnetic field method also includes a part of magnetic characteristics, which is obviously different from that of fig. 12. Fig. 14 is a graph of the detection result of the magnetic barkhausen noise method, and it can be seen that the root mean square value of the magnetic barkhausen noise signal is continuously increased and approximately linear with the continuous increase of the tensile stress, and the microstructure change such as domain wall transition and the like in the process is a main factor influencing the stress. Fig. 15 is a graph of the detection result of the incremental permeability method, and it can be seen that the peak value of the butterfly graph is increasing as the tensile stress increases. The results show that different methods have different stress sensitivity degrees and different leading factors, the various nondestructive testing methods related by the application can measure time in situ, the consistency of the measuring points is ensured, and the main influencing factors at different stages of stress can be extracted, so that an experimental basis is provided for a complex stress evaluation theory.

The above detailed description is for the purpose of describing the invention in detail, and it should not be construed that the detailed description is limited to the description, and it will be apparent to those skilled in the art that various modifications and substitutions can be made without departing from the spirit of the invention.

Claims

1. An electromagnetic composite nondestructive detection sensor is characterized in that: the device comprises an excitation component and a receiving component; the excitation assembly comprises a first excitation coil for receiving an extremely low frequency excitation signal, a low frequency excitation signal or a medium and high frequency excitation signal, and a second excitation coil for receiving the medium and low frequency excitation signal or the high frequency excitation signal; the receiving assembly comprises a magnetic head for receiving longitudinal electromagnetic signals, a magnetic induction intensity detector and a first receiving coil for receiving transverse electromagnetic signals;

2. The electromagnetic composite nondestructive inspection sensor according to claim 1, characterized in that: the first magnetic yoke is a U-shaped magnetic yoke.

3. The electromagnetic composite nondestructive inspection sensor according to claim 1, characterized in that: the magnetic head comprises a shielding shell, and a micron-sized slit is arranged at the bottom of the shell; and a second magnet yoke is arranged in the shell, and a second receiving coil is wound on the second magnet yoke.

4. The electromagnetic composite nondestructive inspection sensor according to claim 1, characterized in that: the magnetic induction intensity detector is a Hall sensor.

5. The electromagnetic composite nondestructive inspection sensor according to claim 1, characterized in that: the first receiving coil is a multilayer coaxial PCB coil, and each layer of PCB coil is reversely wound and connected in series.

6. The electromagnetic composite nondestructive inspection sensor according to claim 1, characterized in that: the sensor also comprises a pre-processing circuit used for filtering and amplifying, and the pre-processing circuit is connected with the magnetic head and/or the magnetic field signal receiver and/or the first receiving coil and/or the exciting coil.

7. The electromagnetic composite nondestructive inspection sensor according to claim 6, wherein: the receiving assembly, the second exciting coil and the preprocessing circuit are arranged on the PCB, and the receiving assembly is arranged in the center of the first magnetic yoke.

8. An electromagnetic composite nondestructive testing system is characterized in that: the system comprises the sensor of any one of claims 1-7, and further comprises an excitation source and a data processing unit, wherein the excitation source is connected with the excitation coil; the data processing unit is connected with the magnetic head, the magnetic field signal receiver and the first receiving coil.

9. An electromagnetic composite nondestructive testing method is characterized in that: the method is applied based on the sensor of any one of claims 1 to 7, and particularly comprises the following steps:

10. The electromagnetic composite nondestructive testing method of claim 9, wherein: the method further comprises the following steps:

the detection signal is received by the magnetic head and/or the first receiving coil, and the stress of the component is determined by evaluating the characteristics of the detection signal.