CN110865118B - Defect depth detection device and method based on staggered probe and pulse eddy current - Google Patents
Defect depth detection device and method based on staggered probe and pulse eddy current Download PDFInfo
- Publication number
- CN110865118B CN110865118B CN201910976347.2A CN201910976347A CN110865118B CN 110865118 B CN110865118 B CN 110865118B CN 201910976347 A CN201910976347 A CN 201910976347A CN 110865118 B CN110865118 B CN 110865118B
- Authority
- CN
- China
- Prior art keywords
- coil
- signal
- ref
- unit
- test piece
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
- G01N27/904—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents with two or more sensors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/26—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring depth
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
- G01N27/9006—Details, e.g. in the structure or functioning of sensors
Landscapes
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Electrochemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
The invention provides a device and a method for detecting defect depth based on an interlaced probe and a pulse eddy current.A signal generator generates periodic pulse signals, the periodic pulse signals are amplified and then applied to two ends of an excitation coil of an interlaced probe unit, a detection coil of the interlaced probe unit is used for detecting magnetic field signals on the surface of a tested piece and converting the magnetic field signals into voltage signals to be output to a signal conditioning unit to filter and amplify the signals and then output to an A/D conversion unit, the converted sampling data is input to a characteristic vector extraction unit based on a time-frequency domain to extract characteristic vectors of a time domain, an amplitude-frequency domain and a phase-frequency domain, and finally the voltage signals are input to a defect depth detection unit based on a random forest to output defect depth information, the excitation coil and the detection coil are arranged in an interlaced mode to reduce a missing detection area, inhibit mutual inductance influence between the coils, improve the signal-to-noise ratio, and increase the robustness of defect detection and reduce the influence of an interference magnetic field by extracting the characteristic vectors of digital signals.
Description
Technical Field
The technology relates to the technical field of design, in particular to a device and a method for detecting defect depth based on a staggered probe and a pulse eddy current.
Background
At present, in economic construction of China, pipeline transportation plays a key role, but pipelines are usually laid under the condition of severe environment, and a plurality of conditions are not suitable for manual operation, so that the pipeline nondestructive defect detection is very important. The defect depth detection of the pulse eddy current can realize more efficient and more accurate scanning detection than single-frequency eddy current, and the problem of blind sight of defects and cracks at a certain depth does not exist. However, the existing pulse eddy current probe is always easily affected by interference signals, a single coil is easy to miss detection, and a defect signal is lost, so that a novel structure is particularly necessary, and in the depth detection of the pulse eddy current defect, the defect size cannot be completely evaluated by the traditional time domain analysis, so that the pulse eddy current probe has very important significance in analyzing an amplitude frequency domain and a phase frequency domain of the signal.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a device and a method for detecting the defect depth based on an interlaced probe and a pulse eddy current.
A defect depth detection device based on an interlaced probe and a pulse eddy current comprises a signal generator, a power amplification unit, an interlaced probe unit, a signal conditioning unit, an A/D (analog/digital) conversion unit and an FPGA (Field Programmable Gate Array) central processing unit, wherein the interlaced probe unit comprises an excitation coil and a detection coil;
firstly, the output end of a signal generator is connected with the input end lead of a power amplification unit, then the output end of the power amplification unit is connected with the excitation coil lead of an interleaved probe unit, a periodic pulse signal generated by the signal generator is amplified by the power amplification unit and then input to the excitation coil of the interleaved probe unit for driving the excitation coil of the interleaved probe unit to generate an alternating magnetic field required for detecting a metal test piece to be detected, then a detection coil of the interleaved probe unit is connected with the input end lead of a signal conditioning unit, the output end of the signal conditioning unit is connected with the input end lead of an A/D conversion unit, a voltage signal output by the interleaved probe unit sequentially passes through the signal conditioning unit and the A/D conversion unit and then is converted into a digital signal, and finally, the output end of the A/D conversion unit is connected with the lead of an FPGA central processing unit, and the digital signal is input to the FPGA central processing unit to generate a depth signal of the surface defect of the metal test piece to be detected;
the signal generator is used for generating a periodic pulse signal with a certain duty ratio;
the power amplification unit is used for amplifying the periodic pulse signal;
the staggered probe unit is used for generating a magnetic field signal for detecting the surface of a tested metal test piece and converting the magnetic field signal into a voltage signal;
the signal conditioning unit is used for filtering and amplifying the voltage signal output by the staggered probe unit;
the A/D conversion unit is used for performing analog-to-digital conversion on the voltage signal processed by the signal conditioning unit;
and the FPGA central processing unit is used for processing the digital signals output by the A/D conversion unit and outputting depth signals of the surface defects of the metal test piece to be tested.
The staggered probe unit comprises an excitation coil and a detection coil, wherein the excitation coil is used for generating a magnetic field signal for detecting the surface of a detected metal test piece, the detection coil is used for converting the magnetic field signal into a voltage signal, a periodic pulse signal amplified by a power amplification unit generates an alternating magnetic field in the excitation coil and is applied to the detected metal test piece, the detection coil detects the magnetic field signal above the detected metal test piece and converts the magnetic field signal into the voltage signal, the excitation coil comprises 3 coils with the same parameters and is arranged in a triangular shape, the detection coil of the staggered probe unit comprises 3 coils with the same parameters, and each detection coil is arranged inside the excitation coil in a coaxial mode, specifically expressed as:
r outer cover ＝R Outer cover -R Inner part
3r Inner part ＝r Outer cover
3R Inner part ＝2R Outer cover
In the formula, R Outer cover To excite the outer radius of the coil, R Inner part To excite the inner radius of the coil, r Outer cover To detect the outer radius of the coil, r Inner part Detecting the inner radius of the coil, d is the distance between any two exciting coils, mu is the magnetic conductivity of the metal test piece to be detected, sigma is the electric conductivity of the metal test piece to be detected, v is the moving speed of the staggered probe unit, and a is the angle between the moving direction of the staggered probe unit and the horizontal plane.
The FPGA central processing unit comprises a time-frequency domain-based feature vector extraction unit and a random forest-based defect depth detection unit, firstly, a digital signal output by the A/D conversion unit is subjected to time-frequency domain-based feature vector extraction to construct a feature vector, and then the depth information of the surface defect of the metal test piece to be detected is output by the random forest-based defect depth detection unit;
the time-frequency domain-based feature vector extraction unit is used for constructing feature vectors according to the characteristics of a time domain, an amplitude-frequency domain and a phase-frequency domain;
the defect depth detection unit based on the random forest is used for converting the characteristic vector into depth information of the surface defect of the metal test piece to be detected.
A detection method of a defect depth detection device based on an interlaced probe and a pulse eddy current comprises the following steps:
step 1: acquiring a defect signal sample set on the surface of a defective metal test piece to be tested, scanning the surface of the defective metal test piece at a constant speed by using an interlaced probe unit, converting an electromagnetic signal above the defect surface of the acquired metal test piece to a voltage signal, transmitting the voltage signal to an A/D conversion unit, and converting the voltage signal into the defect signal sample set by the A/D conversion unit, wherein the defect signal sample set is specifically represented as:
wherein:
Y 1 ＝(y 11 y 12 … y 1k … y 1n )，
Y 2 ＝(y 21 y 22 … y 2k … y 2n )，
Y 3 ＝(y 31 y 32 … y 3k … y 3n )，
wherein n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y 1k Data sampled for coil No. 1 at time k, y 2k Data sampled for coil No. 2 at time k, y 3k N, Y for the sample data of coil No. 3 at time k, k =1,2,3 1 Data sampled for coil number 1 in one sampling period, Y 2 Data sampled for coil number 2 in one sampling period, Y 3 Sampling data of a No. 3 coil in a sampling period;
and 2, step: collecting a reference signal sample set on the surface of a non-defective metal test piece to be tested, uniformly scanning the surface of the non-defective metal test piece by using a staggered probe unit, converting an electromagnetic signal above the non-defective surface of the collected metal test piece into a voltage signal, transmitting the voltage signal to an A/D (analog/digital) conversion unit, and converting the voltage signal into the reference signal sample set by the A/D conversion unit, wherein the reference signal sample set is specifically represented as follows:
wherein:
Y ref 1 ＝(y ref 11 y ref 12 … y ref 1k … y ref 1n )，
Y ref 2 ＝(y ref 21 y ref 22 … y ref 2k … y ref 2n )，
Y ref 3 ＝(y ref 31 y ref 32 … y ref 3k … y ref 3n )，
wherein n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 To excite the pulse period, y ref 1k Coil number 1 at time kReference sample data of y ref 2k Reference sample data for coil No. 2 at time k, y ref 3k For reference sample data of coil No. 3 at the k-th time instant, k =1,2,3 ref 1 Reference sample data for coil No. 1 in one sample period, Y ref 2 Reference sample data for coil No. 2 in one sample period, Y ref 3 Reference sampling data for coil No. 3 in one sampling period;
and step 3: inputting the defect signal sample set and the reference signal sample set into a time-frequency domain-based feature vector extraction unit of an FPGA central processing unit to solve Y i Time domain characteristic parameter Δ S of i ：
In the formula, delta S i Is Y i N is the number of sampling points in a sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref ik Reference sample data for coil i at time k, y ik For the sample data of coil i at the k-th time, i =1,2,3, k =1,2,3.. N, r Outer cover Detecting the outer radius of the coil, wherein v is the moving speed of the staggered probe unit;
and 4, step 4: for Y i And Y ref i Performing discrete Fourier transform to obtain Y i Amplitude spectrum G of i (f) And Y ref i Amplitude spectrum G of ref i (f) Then Y is i Characteristic parameter Delta G of amplitude-frequency domain i Comprises the following steps:
in the formula, delta G i Is Y i J is an imaginary part, f is a frequency variable of an amplitude frequency spectrum after discrete Fourier transform, q is a penetration frequency, the penetration frequency indicates that when the frequency of an excitation signal is q, the excitation signal can penetrate through an iron plate, mu is the magnetic conductivity of a metal test piece to be measured, sigma is the electric conductivity of the metal test piece to be measured, delta is the thickness of the metal test piece to be measured, n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref ik Reference sample data for coil i at time k, y ik I =1,2,3, k =1,2,3.. N for the sample data of coil i at the k-th time;
and 5: solving for Y i Phase zero crossing coordinates H i And Y ref i Phase zero crossing point coordinate H ref i ：
Then Y is i Characteristic parameter Δ H of phase frequency domain i Comprises the following steps:
in the formula,. DELTA.H i Is Y i Characteristic parameter of the phase frequency domain of H i Is Y i Phase zero crossing point coordinates of (H) ref i Is Y ref i The phase zero crossing point coordinates of (1);
and 6: construction of Y i Characteristic vector J of i ：
J i ＝(△S i ,△G i ,△H i )
In the formula, J i Is Y i Is characteristic vector of (a;,. DELTA.S) i Is Y i Of time domain characteristic parameter, Δ G i Is Y i Is the amplitude-frequency domain characteristic parameter, delta H i Is Y i I =1,2,3;
and 7: y to be constructed i Characteristic vector J of i And the depth information of the surface defect of the metal test piece to be tested is output as the input of a defect depth detection unit based on a random forest of the FPGA central processing unit.
The invention has the beneficial effects that:
compared with the prior art, 1) the device adopts an interlaced probe unit, the exciting coil and the detecting coil are arranged in an interlaced way, the missing detection area is reduced, the mutual inductance influence between the coils can be inhibited due to the interlaced structure, and the signal-to-noise ratio is improved; 2) The feature vector extraction unit based on the time-frequency domain is used for extracting the feature vector of the digital signal, so that the robustness of defect detection is improved, and the influence of an interference magnetic field is reduced.
Drawings
FIG. 1 is a block diagram of a defect depth detection device based on an interleaved probe and pulsed eddy current.
FIG. 2 is a schematic circuit diagram of a defect depth detection device based on an interleaved probe and pulsed eddy current.
Fig. 3 is a view showing the structure of the interleaved probe unit.
FIG. 4 is a flow chart of a method for detecting a defect depth detection device based on an interlaced probe and a pulsed eddy current.
Detailed Description
The technical features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the accompanying drawings.
As shown in fig. 1, a device for detecting defect depth based on an interleaved probe and a pulse eddy current comprises a signal generator, a power amplification unit, an interleaved probe unit, a signal conditioning unit, an a/D conversion unit, and an FPGA central processing unit, wherein the interleaved probe unit comprises an excitation coil and a detection coil;
firstly, a periodic pulse signal generated by a signal generator is amplified by a power amplification unit and then input to an interleaved probe unit for driving the interleaved probe unit to generate an alternating magnetic field required when a detected metal test piece is detected, then a voltage signal output by the interleaved probe unit is converted into a digital signal after sequentially passing through a signal conditioning unit and an A/D conversion unit, and finally the digital signal is input to an FPGA central processing unit to generate a depth signal of the surface defect of the detected metal test piece;
the signal generator is used for generating a periodic pulse signal with a certain duty ratio;
the power amplification unit is used for amplifying the periodic pulse signal;
the staggered probe unit is used for generating a magnetic field signal for detecting the surface of the tested metal test piece and converting the magnetic field signal into a voltage signal;
the signal conditioning unit is used for filtering and amplifying the voltage signal output by the staggered probe unit;
the A/D conversion unit is used for carrying out analog-to-digital conversion on the voltage signal processed by the signal conditioning unit;
the FPGA (Field Programmable Gate Array) central processing unit is used for processing the digital signals output by the A/D conversion unit and outputting depth signals of the surface defects of the metal test piece to be tested.
As shown in fig. 2, the output end of the signal generator is correspondingly connected to the input end of the power amplification unit, the output end of the power amplification unit is correspondingly connected to the excitation coil of the interleaved probe unit, the coil of the interleaved probe unit is connected to the input end of the signal conditioning unit, the output end of the signal conditioning unit is connected to the input end of the a/D conversion unit, and the output end of the a/D conversion unit is connected to the FPGA central processing unit.
In this example, the model of the signal generator is AFG3021, the model of the power amplifier is TL071CDR, the model of the a/D conversion module is ADS7844, and the model of the FPGA is EP4CE1FC8.
As shown in fig. 3, the interleaved probe unit is composed of an excitation coil and a detection coil, the excitation coil is used for generating a magnetic field signal for detecting the surface of the metal test piece to be detected, the detection coil is used for converting the magnetic field signal into a voltage signal, the periodic pulse signal amplified by the power amplification unit generates an alternating magnetic field in the excitation coil and is applied to the metal test piece to be detected, the detection coil detects the magnetic field signal above the metal test piece to be detected and converts the magnetic field signal into the voltage signal, the excitation coil is composed of 3 coils with the same parameters and is arranged in a delta shape, the detection coil of the interleaved probe unit is composed of 3 coils with the same parameters, and each detection coil is arranged inside the excitation coil in a coaxial manner, specifically expressed as:
r outer cover ＝R Outer cover -R Inner part
3r Inner part ＝r Outer cover
3R Inner part ＝2R Outer cover
In the formula, R Outer cover For exciting the outer radius of the coil, R Inner part To excite the inner radius of the coil, r Outer cover To detect the outer radius of the coil, r Inner part Detecting the inner radius of the coil, d is the distance between any two exciting coils, and mu is the measured metal test pieceAnd the magnetic conductivity, sigma, v and a are respectively the electric conductivity of the metal test piece to be tested, the moving speed of the staggered probe unit and the angle between the moving direction of the staggered probe unit and the horizontal plane.
Specific parameters of the excitation coil and the detection coil selected in the embodiment are shown in table 1, and parameters of a metal test piece to be tested and a staggered probe unit movement experiment are set in table 2.
TABLE 1 parameter setting table for excitation coil and detection coil
TABLE 2 Metal test piece to be tested and staggered probe unit mobile experiment parameter setting table
The FPGA central processing unit comprises a time-frequency domain-based feature vector extraction unit and a random forest-based defect depth detection unit, firstly, a digital signal output by the A/D conversion unit is subjected to time-frequency domain-based feature vector extraction to construct a feature vector, and then the depth information of the surface defect of the metal test piece to be detected is output by the random forest-based defect depth detection unit;
the time-frequency domain-based feature vector extraction unit is used for constructing feature vectors according to the characteristics of a time domain, an amplitude-frequency domain and a phase-frequency domain;
and the defect depth detection unit based on the random forest is used for converting the characteristic vector into depth information of the surface defect of the tested metal test piece.
As shown in fig. 4, a method for detecting a defect depth detection device based on an interlaced probe and a pulsed eddy current includes the following steps:
step 1: acquiring a defect signal sample set on the surface of a defective metal test piece to be tested, scanning the surface of the defective metal test piece at a constant speed by using an interlaced probe unit, converting an electromagnetic signal above the defect surface of the detected metal test piece into a voltage signal, transmitting the voltage signal to an A/D conversion unit, and converting the voltage signal into the defect signal sample set through the A/D conversion unit, wherein the defect signal sample set is specifically expressed as follows:
wherein:
Y 1 ＝(y 11 y 12 … y 1k … y 1n )，
Y 2 ＝(y 21 y 22 … y 2k … y 2n )，
Y 3 ＝(y 31 y 32 … y 3k … y 3n )，
wherein n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 To excite the pulse period, y 1k Data sampled at the k-th time for coil No. 1, y 2k Data sampled for coil No. 2 at time k, y 3k N, Y for the sample data of coil No. 3 at time k, k =1,2,3 1 Data sampled for coil number 1 in one sampling period, Y 2 Data sampled for coil number 2 in one sampling period, Y 3 Sampling data for coil No. 3 in a sampling period;
step 2: collecting a reference signal sample set on the surface of a non-defective metal test piece to be tested, uniformly scanning the surface of the non-defective metal test piece by using a staggered probe unit, converting an electromagnetic signal above the non-defective surface of the collected metal test piece into a voltage signal, transmitting the voltage signal to an A/D (analog/digital) conversion unit, and converting the voltage signal into the reference signal sample set by the A/D conversion unit, wherein the reference signal sample set is specifically represented as follows:
wherein:
Y ref 1 ＝(y ref 11 y ref 12 … y ref 1k … y ref 1n )，
Y ref 2 ＝(y ref 21 y ref 22 … y ref 2k … y ref 2n )，
Y ref 3 ＝(y ref 31 y ref 32 … y ref 3k … y ref 3n )，
wherein n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref 1k Reference sample data for coil No. 1 at time k, y ref 2k Reference sample data for coil No. 2 at time k, y ref 3k For reference sample data of coil No. 3 at the k-th time instant, k =1,2,3 ref 1 Reference sample data for coil No. 1 in one sample period, Y ref 2 Reference sample data for coil number 2 in one sample period, Y ref 3 Reference sampling data for coil No. 3 in one sampling period;
and step 3: inputting the defect signal sample set and the reference signal sample set into a time-frequency domain-based feature vector extraction unit of an FPGA central processing unit to solve Y i Time domain characteristic parameter Δ S of i ：
In the formula,. DELTA.S i Is Y i N is the number of sampling points in a sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref ik Reference sample data for coil i at time k, y ik For the sample data of coil i at the k-th time, i =1,2,3, k =1,2,3.. N, r Outer cover Detecting the outer radius of the coil, wherein v is the moving speed of the staggered probe unit;
and 4, step 4: for Y i And Y ref i Performing discrete Fourier transform to obtain Y i Amplitude spectrum G of i (f) And Y ref i Amplitude spectrum G of ref i (f) Then Y is i Characteristic parameter Delta G of amplitude-frequency domain i Comprises the following steps:
in the formula, delta G i Is Y i J is an imaginary part, f is a frequency variable of an amplitude frequency spectrum after discrete Fourier transform, q is a penetration frequency, the penetration frequency indicates that when the frequency of an excitation signal is q, the excitation signal can penetrate through an iron plate, mu is the magnetic permeability of a metal test piece to be measured, sigma is the electric conductivity of the metal test piece to be measured, delta is the thickness of the metal test piece to be measured, delta is set to be 6mm in the embodiment,n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref ik Reference sample data for coil i at time k, y ik I =1,2,3, k =1,2,3.. N for the sample data of coil No. i at the k-th time;
and 5: solving for Y i Phase zero crossing point coordinate H i And Y ref i Phase zero crossing point coordinate H ref i ：
Then Y is i Characteristic parameter Δ H of phase frequency domain i Comprises the following steps:
in the formula, delta H i Is Y i Characteristic parameter of the phase frequency domain of H i Is Y i Phase zero crossing point coordinates of (H) ref i Is Y ref i The phase zero crossing point coordinates of (1);
step 6: construction of Y i Characteristic vector J of i ：
J i ＝(△S i ,△G i ,△H i )
In the formula, J i Is Y i Characteristic vector of (D), delta S i Is Y i Is a time domain characteristic parameter, Δ G i Is Y i Is the amplitude-frequency domain characteristic parameter, delta H i Is Y i I =1,2,3;
and 7: y to be constructed i Characteristic vector J of i And the depth information of the surface defect of the metal test piece to be tested is output as the input of a defect depth detection unit based on a random forest of the FPGA central processing unit.
Five groups of experimental tests are carried out according to the technical scheme, the test results are shown in table 3, and it can be seen from table 3 that the technical scheme provided by the invention can effectively test the defect depth of the surface of the tested metal test piece, and the test error is controlled within 0.1 mm.
TABLE 3 test results of the experiments
Claims (3)
1. A defect depth detection device based on an interleaved probe and a pulse eddy current is characterized by comprising a signal generator, a power amplification unit, an interleaved probe unit, a signal conditioning unit, an A/D conversion unit and an FPGA central processing unit, wherein the interleaved probe unit comprises an excitation coil and a detection coil;
firstly, the output end of a signal generator is connected with the input end lead of a power amplifying unit, then the output end of the power amplifying unit is connected with the exciting coil lead of an interleaved probe unit, a periodic pulse signal generated by the signal generator is amplified by the power amplifying unit and then is input into the exciting coil of the interleaved probe unit for driving the exciting coil of the interleaved probe unit to generate an alternating magnetic field required when a detected metal test piece is detected, then a detection coil of the interleaved probe unit is connected with the input end lead of a signal conditioning unit, the output end of the signal conditioning unit is connected with the input end lead of an A/D conversion unit, a voltage signal output by the interleaved probe unit sequentially passes through the signal conditioning unit and the A/D conversion unit and then is converted into a digital signal, and finally the output end of the A/D conversion unit is connected with the FPGA central processing unit lead, and the digital signal is input into the FPGA central processing unit to generate a depth signal of the surface defect of the detected metal test piece;
the signal generator is used for generating a periodic pulse signal with a certain duty ratio;
the power amplification unit is used for amplifying the periodic pulse signal;
the staggered probe unit is used for generating a magnetic field signal for detecting the surface of a tested metal test piece and converting the magnetic field signal into a voltage signal;
the signal conditioning unit is used for filtering and amplifying the voltage signal output by the staggered probe unit;
the A/D conversion unit is used for performing analog-to-digital conversion on the voltage signal processed by the signal conditioning unit;
the FPGA central processing unit is used for processing the digital signal output by the A/D conversion unit and outputting a depth signal of the surface defect of the metal test piece to be tested;
the staggered probe unit comprises an excitation coil and a detection coil, wherein the excitation coil is used for generating a magnetic field signal for detecting the surface of a detected metal test piece, the detection coil is used for converting the magnetic field signal into a voltage signal, a periodic pulse signal amplified by a power amplification unit generates an alternating magnetic field in the excitation coil and is applied to the detected metal test piece, the detection coil detects the magnetic field signal above the detected metal test piece and converts the magnetic field signal into the voltage signal, the excitation coil comprises 3 coils with the same parameters and is arranged in a triangular shape, the detection coil of the staggered probe unit comprises 3 coils with the same parameters, and each detection coil is arranged inside the excitation coil in a coaxial mode, specifically expressed as:
r outer cover ＝R Outer cover -R Inner part
3r Inner part ＝r Outer cover
3R Inner part ＝2R Outer cover
In the formula, R Outer cover For exciting the outer radius of the coil, R Inner part For exciting in a coilRadius r Outer cover Is the outer radius of the induction coil, r Inner part The inner radius of the induction coil, d is the distance between any two exciting coils, mu is the magnetic conductivity of the metal test piece to be measured, sigma is the electric conductivity of the metal test piece to be measured, v is the moving speed of the staggered probe unit, and a is the angle between the moving direction of the staggered probe unit and the horizontal plane.
2. The device for detecting the defect depth based on the staggered probe and the pulsed eddy current as claimed in claim 1, wherein the FPGA central processing unit comprises a time-frequency domain-based feature vector extraction unit and a random forest-based defect depth detection unit, firstly, the digital signal output by the a/D conversion unit passes through the time-frequency domain-based feature vector extraction unit to construct a feature vector, and then the random forest-based defect depth detection unit outputs the depth information of the surface defect of the metal test piece to be detected;
the time-frequency domain-based feature vector extraction unit is used for constructing feature vectors according to the characteristics of a time domain, an amplitude-frequency domain and a phase-frequency domain;
the defect depth detection unit based on the random forest is used for converting the characteristic vectors into depth information of the surface defects of the metal test piece to be detected.
3. The method for detecting the defect depth detection device based on the staggered probe and the pulse eddy current as claimed in any one of claims 1-2, which is characterized by comprising the following steps:
step 1: acquiring a defect signal sample set on the surface of a defective metal test piece to be tested, scanning the surface of the defective metal test piece at a constant speed by using an interlaced probe unit, converting an electromagnetic signal above the defect surface of the acquired metal test piece to a voltage signal, transmitting the voltage signal to an A/D conversion unit, and converting the voltage signal into the defect signal sample set by the A/D conversion unit, wherein the defect signal sample set is specifically represented as:
wherein:
Y 1 ＝(y 11 y 12 …y 1k …y 1n )，
Y 2 ＝(y 21 y 22 …y 2k …y 2n )，
Y 3 ＝(y 31 y 32 …y 3k …y 3n )，
wherein n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 To excite the pulse period, y 1k Data sampled for coil No. 1 at time k, y 2k Data sampled for coil No. 2 at time k, y 3k N, Y for the sample data of coil No. 3 at time k, k =1,2,3 1 Data sampled for coil number 1 in one sampling period, Y 2 Data sampled for coil number 2 in one sampling period, Y 3 Sampling data for coil No. 3 in a sampling period;
step 2: collecting a reference signal sample set on the surface of a non-defective metal test piece to be tested, uniformly scanning the surface of the non-defective metal test piece by using a staggered probe unit, converting an electromagnetic signal above the non-defective surface of the collected metal test piece into a voltage signal, transmitting the voltage signal to an A/D (analog/digital) conversion unit, and converting the voltage signal into the reference signal sample set by the A/D conversion unit, wherein the reference signal sample set is specifically represented as follows:
wherein:
Y ref 1 ＝(y ref 11 y ref 12 …y ref 1k …y ref 1n )，
Y ref 2 ＝(y ref 21 y ref 22 …y ref 2k …y ref 2n )，
Y ref 3 ＝(y ref 31 y ref 32 …y ref 3k …y ref 3n )，
wherein n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref 1k Reference sample data for coil No. 1 at time k, y ref 2k Reference sample data for coil No. 2 at time k, y ref 3k N, Y for reference sample data for coil No. 3 at time k, k =1,2,3 ref 1 Reference sample data for coil No. 1 in one sample period, Y ref 2 Reference sample data for coil No. 2 in one sample period, Y ref 3 Reference sampling data for coil No. 3 in one sampling period;
and step 3: inputting the defect signal sample set and the reference signal sample set into a time-frequency domain-based feature vector extraction unit of an FPGA central processing unit to solve Y i Time domain characteristic parameter Δ S of i ：
In the formula, delta S i Is Y i N is the number of sampling points in a sampling period,
T 1 for a sampling period, T 2 For the excitation pulse period, y ref ik Reference sample data for coil i at time k, y ik For the sample data of coil i at the k-th time, i =1,2,3, k =1,2,3.. N, r Outer cover Is the outer radius of the induction coil, and v is the moving speed of the staggered probe unit;
and 4, step 4: for Y i And Y ref i Performing discrete Fourier transform to respectively obtain Y i Amplitude spectrum G of i (f) And Y ref i Amplitude spectrum G of ref i (f) Then Y is i Characteristic parameter Delta G of amplitude-frequency domain i Comprises the following steps:
in the formula, Δ G i Is Y i J is an imaginary part, f is a frequency variable of an amplitude frequency spectrum after discrete Fourier transform, q is a penetration frequency, the penetration frequency represents that when the frequency of an excitation signal is q, the excitation signal can penetrate through a metal test piece to be measured, mu is the magnetic conductivity of the metal test piece to be measured, sigma is the electric conductivity of the metal test piece to be measured, delta is the thickness of the metal test piece to be measured, n is the number of sampling points in one sampling period,
T 1 for a sampling period, T 2 To activateExcitation pulse period, y ref ik Reference sample data for coil i at time k, y ik I =1,2,3, k =1,2,3.. N for the sample data of coil i at the k-th time; and 5: solving for Y i Phase zero crossing point coordinate H i And Y ref i Phase zero crossing point coordinate H ref i ：
Then Y is i Characteristic parameter Δ H of phase frequency domain i Comprises the following steps:
in the formula, delta H i Is Y i Characteristic parameter of the phase frequency domain of H i Is Y i Phase zero-crossing coordinates of (c), H ref i Is Y ref i The phase zero crossing point coordinates of (1);
step 6: construction of Y i Characteristic vector J of i ：
J i ＝(△S i ,△G i ,△H i )
In the formula, J i Is Y i Is characteristic vector of (a;,. DELTA.S) i Is Y i Is a time domain characteristic parameter, Δ G i Is Y i Is the amplitude-frequency domain characteristic parameter, delta H i Is Y i I =1,2,3;
and 7: y to be constructed i Characteristic vector J of i And the depth information of the surface defect of the metal test piece to be tested is output as the input of a defect depth detection unit based on the random forest of the FPGA central processing unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910976347.2A CN110865118B (en) | 2019-10-15 | 2019-10-15 | Defect depth detection device and method based on staggered probe and pulse eddy current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910976347.2A CN110865118B (en) | 2019-10-15 | 2019-10-15 | Defect depth detection device and method based on staggered probe and pulse eddy current |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110865118A CN110865118A (en) | 2020-03-06 |
| CN110865118B true CN110865118B (en) | 2022-10-21 |
Family
ID=69652789
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910976347.2A Active CN110865118B (en) | 2019-10-15 | 2019-10-15 | Defect depth detection device and method based on staggered probe and pulse eddy current |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110865118B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110986752B (en) * | 2019-11-26 | 2021-05-18 | 深圳市智能机器人研究院 | Angle self-correction method and system based on multi-frequency excitation |
| CN111597717B (en) * | 2020-05-19 | 2023-04-07 | 电子科技大学 | Frequency-selecting band eddy current nondestructive testing analytical calculation method containing local thinning defect |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000008458A1 (en) * | 1998-08-06 | 2000-02-17 | Mitsubishi Heavy Industries, Ltd. | Eddy-current flaw detector probe |
| JP5946086B2 (en) * | 2012-03-19 | 2016-07-05 | 株式会社日立製作所 | Eddy current inspection device, eddy current inspection probe, and eddy current inspection method |
| US10895555B2 (en) * | 2015-03-30 | 2021-01-19 | Structural Integrity Associates, Inc. | System for in-line inspection using a dynamic pulsed eddy current probe and method thereof |
| GB201514470D0 (en) * | 2015-08-14 | 2015-09-30 | The Technology Partnership Plc | Material inspection |
| CN107422029B (en) * | 2017-04-28 | 2020-11-03 | 陕西科技大学 | Device and method for accurately detecting defects of metal plate |
| CN109115868B (en) * | 2018-09-29 | 2022-03-25 | 东北大学 | Defect depth detection device and method based on pulse eddy current |
| CN109142514B (en) * | 2018-09-29 | 2022-04-01 | 东北大学 | Defect detection device and method based on pulse eddy current array |
-
2019
- 2019-10-15 CN CN201910976347.2A patent/CN110865118B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110865118A (en) | 2020-03-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Angani et al. | The pulsed eddy current differential probe to detect a thickness variation in an insulated stainless steel | |
| CN103257182B (en) | A kind of impulse eddy current defect quantitative detection method and detection system | |
| CN103336049B (en) | A kind of pulse eddy current detection method and device eliminating Lift-off effect | |
| CN110057904B (en) | Method and device for quantitatively detecting defects of moving metal component | |
| CN103954684B (en) | A kind of method utilizing leakage field rate of change to carry out Non-Destructive Testing | |
| CN110865118B (en) | Defect depth detection device and method based on staggered probe and pulse eddy current | |
| CN109142514B (en) | Defect detection device and method based on pulse eddy current array | |
| CN109115868B (en) | Defect depth detection device and method based on pulse eddy current | |
| CN109444257B (en) | Pulse eddy current detection device and method based on frequency domain lift-off intersection point | |
| CN103149272A (en) | Sub-saturated time-division and multi-frequency magnetic flux leakage testing method | |
| CN104977352A (en) | Defect and stress non-destructive testing system and non-destructive testing method based on pulsed eddy current and Barkhausen | |
| Ribeiro et al. | Liftoff correction based on the spatial spectral behavior of eddy-current images | |
| CN106501372B (en) | Monitoring and positioning method based on wavelet packet analysis track switch crackle | |
| CN102269814A (en) | Method for intelligent detection on quality of foundation pile | |
| CN109632941A (en) | A method of inhibiting magnetic leakage signal lift-off interference | |
| CN113358738A (en) | Ferromagnetic material fatigue damage characterization method based on magnetoacoustic emission signal hysteresis characteristic | |
| CN113092577B (en) | Rail defect detection system based on multifrequency excitation vortex and detection method thereof | |
| Sun et al. | A performance improved ACFM-TMR detection system with tradeoff denoising algorithm | |
| CN104330469A (en) | Pulse eddy current detection lift-off effect inhibiting method based on high-pass filtering | |
| CN108760873A (en) | Metal material tensile strength quantitative testing device based on incremental permeability and method | |
| CN115406960A (en) | Digital multi-frequency eddy current signal processing method | |
| Gao et al. | Defect identification and classification of multi-frequency eddy current test based on spectrum method | |
| CN102841130A (en) | Apparatus and method for detecting internal and external crack defects of metal material | |
| CN113155954B (en) | Pulse eddy current detection system and method for detecting defects of conductor structure | |
| CN105319265A (en) | Pulse vortex detection lift-off eliminating novel algorithm |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |