阅读说明：本技术 一种多频激励涡流场相位梯度谱无损检测方法及系统 (Multi-frequency excitation eddy current field phase gradient spectrum nondestructive testing method and system ) 是由 张荣华 高鹏程 史可宇 于 2019-09-16 设计创作，主要内容包括：本发明公开一种多频激励涡流场相位梯度谱无损检测方法及系统,所述方法首先获取被测物体在不同激励频率下的正弦激励电压信号和平面扫描路径各点处与所述正弦激励电压信号对应的感应电压信号；其次利用数字相敏解调技术,对所述感应电压信号进行解调,获得相位值；然后将不同激励频率下的相位值做梯度变换,获得平面内沿X轴位置方向的相位梯度；最后根据不同激励频率下的沿X轴位置方向的相位梯度确定被测物体缺陷所在位置。本发明从二维的角度出发,利用相位梯度识别出缺陷在被测样件中所处的位置,相比于一维角度出发,进一步提高了识别的准确度。(The invention discloses a nondestructive testing method and a nondestructive testing system for a multi-frequency excitation eddy current field phase gradient spectrum, wherein the method comprises the steps of firstly, acquiring sinusoidal excitation voltage signals of a tested object under different excitation frequencies and induction voltage signals corresponding to the sinusoidal excitation voltage signals at each point of a plane scanning path; secondly, demodulating the induced voltage signal by using a digital phase-sensitive demodulation technology to obtain a phase value; then, carrying out gradient transformation on the phase values under different excitation frequencies to obtain a phase gradient along the X-axis position direction in a plane; and finally, determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies. The invention is based on the two-dimensional angle, and utilizes the phase gradient to identify the position of the defect in the sample to be measured, thereby further improving the identification accuracy compared with the one-dimensional angle.)

1. A multi-frequency excitation eddy current field phase gradient spectrum nondestructive testing method is characterized by comprising the following steps:

acquiring sinusoidal excitation voltage signals of a measured object under different excitation frequencies;

acquiring an induced voltage signal corresponding to the sinusoidal excitation voltage signal at each point of a planar scanning path;

demodulating the induced voltage signal by using a digital phase-sensitive demodulation technology to obtain a phase value;

carrying out gradient transformation on phase values under different excitation frequencies to obtain phase gradients in the X-axis position direction in a plane;

And determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies.

2. the method for nondestructive testing of the phase gradient spectrum of the multi-frequency excitation eddy current field according to claim 1, wherein the formula of the phase value is as follows:

wherein phi is a phase value, I is a real part of the induced voltage signal,R is the imaginary part of the induced voltage signal,r (n) is a sinusoidal excitation voltage signal,i (n) is a cosine excitation voltage signal,V_x(n) is an ideal induced voltage signal;k is the variation of the modulus values of the induction voltage signal and the excitation voltage signal, and phi is the variation of the phase angle of the induction voltage signal and the excitation voltage signal; n is 0: N-1, and N is the number of sampling points in a single period.

3. the method for nondestructive testing of the phase gradient spectrum of the multi-frequency excitation eddy current field according to claim 1, wherein the calculation formula of the phase gradient along the X-axis position direction in the plane is as follows:

wherein, g_x(X, y) is the phase gradient along the X-axis position direction, and the phase value data is a two-dimensional arrayi and j represent different positions in the X-axis direction and the Y-axis direction, respectively.

4. the method for nondestructive testing of the multi-frequency excitation eddy current field phase gradient spectrum according to claim 1, wherein the determining the position of the defect of the object to be tested according to the phase gradient along the X-axis position direction under different excitation frequencies specifically comprises:

Using a 2-dimensional gray filling contour map to draw phase gradients along the X-axis position direction under different excitation frequencies to obtain a phase gradient map;

And determining the position of the defect of the measured object according to the phase gradient map.

5. a multi-frequency excited eddy current field phase gradient spectroscopy nondestructive testing system, the system comprising:

The direct digital frequency synthesizer DDS is used for generating sinusoidal excitation voltage signals under different excitation frequencies;

the detection probe is connected with the DDS and used for detecting a detected object according to the sinusoidal excitation voltage signal to obtain an induction voltage signal;

And the industrial personal computer is respectively connected with the detection probe and the DDS and is used for receiving the sinusoidal excitation voltage signal and the induced voltage signal and determining the position of the defect of the detected object according to the method of any one of claims 1 to 4.

6. the multi-frequency excited eddy current field phase gradient spectroscopy nondestructive testing system of claim 5, further comprising:

And the acquisition card is respectively connected with the detection probe, the DDS and the industrial personal computer, is used for acquiring the sinusoidal excitation voltage signal and the induction voltage signal and sending the sinusoidal excitation voltage signal and the induction voltage signal to the industrial personal computer.

7. the multi-frequency excited eddy current field phase gradient spectroscopy nondestructive testing system of claim 6, further comprising:

The V/I converter is respectively connected with the DDS and the detection probe, and is used for converting the sinusoidal excitation voltage signal generated by the DDS into a sinusoidal excitation current signal and sending the sinusoidal excitation current signal to the detection probe so that the detection probe detects a detected object according to the sinusoidal excitation current signal to obtain an induced voltage signal;

And the linear power supply is respectively connected with the V/I converter and the detection probe and is used for supplying electric energy to the V/I converter and the detection probe.

8. the multi-frequency excited eddy current field phase gradient spectroscopy nondestructive testing system of claim 5, further comprising:

and the three-axis scanning platform is respectively connected with the industrial personal computer and the detection probe and is used for driving the detection probe to detect the detected object on the aluminum plate according to a preset scanning path according to the control command sent by the industrial personal computer.

9. The multifrequency excitation eddy current field phase gradient spectroscopy nondestructive testing system of claim 7, wherein the test probe comprises:

the eddy current sensor is connected with the V/I converter and used for detecting a measured object according to the sinusoidal excitation current signal to obtain an induced voltage signal;

and the amplifying circuit is connected with the eddy current sensor and the acquisition card respectively and is used for amplifying the induced voltage signal.

Technical Field

The invention relates to the technical field of nondestructive testing, in particular to a nondestructive testing method and system for a multi-frequency excitation eddy current field phase gradient spectrum.

Background

because the electromagnetic field belongs to a soft field, the electromagnetic eddy current detection method is very sensitive to the detected environment and the boundary condition of the detected object. Therefore, optimally designing the coil geometry and the excitation-measurement strategy are always the research focus of electromagnetic eddy current testing. In the existing electromagnetic eddy current detection method, the phase gradient is used as the characteristic quantity of a detection signal, so that the defect is mostly measured from a one-dimensional angle, and the position of the defect cannot be accurately identified.

How to overcome the above problems and how to find a position where the defect can be accurately identified in the sample under test from a two-dimensional perspective is a problem that needs to be solved in the field.

disclosure of Invention

the invention aims to provide a nondestructive testing method and a nondestructive testing system for a multi-frequency excitation eddy current field phase gradient spectrum, which can accurately identify the position of a defect in a sample to be tested.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a nondestructive testing method for multi-frequency excitation eddy current field phase gradient spectrum, which comprises the following steps:

Acquiring sinusoidal excitation voltage signals of a measured object under different excitation frequencies;

acquiring an induced voltage signal corresponding to the sinusoidal excitation voltage signal at each point of a planar scanning path;

demodulating the induced voltage signal by using a digital phase-sensitive demodulation technology to obtain a phase value;

Carrying out gradient transformation on phase values under different excitation frequencies to obtain phase gradients in the X-axis position direction in a plane;

and determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies.

Optionally, the phase value formula is:

Wherein phi is a phase value, I is a real part of the induced voltage signal,r is the imaginary part of the induced voltage signal,r (n) is a sinusoidal excitation voltage signal,i (n) is a cosine excitation voltage signal,V_x(n) is an ideal induced voltage signal;K is the variation of the modulus values of the induction voltage signal and the excitation voltage signal, and phi is the variation of the phase angle of the induction voltage signal and the excitation voltage signal; n is 0: N-1, and N is the number of sampling points in a single period.

optionally, the calculation formula of the phase gradient along the X-axis position direction in the plane is:

wherein, g_x(X, y) is the phase gradient along the X-axis position direction, and the phase value data is a two-dimensional arrayi-1, 2, … p, j-1, 2, … q, i and j represent different positions in the X-axis direction and the Y-axis direction, respectively.

optionally, the determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies specifically includes:

using a 2-dimensional gray filling contour map to draw phase gradients along the X-axis position direction under different excitation frequencies to obtain a phase gradient map;

and determining the position of the defect of the measured object according to the phase gradient map.

The invention also provides a multi-frequency excitation eddy current field phase gradient spectrum nondestructive testing system, which comprises:

the direct digital frequency synthesizer DDS is used for generating sinusoidal excitation voltage signals under different excitation frequencies;

the detection probe is connected with the DDS and used for detecting a detected object according to the sinusoidal excitation voltage signal to obtain an induction voltage signal;

and the industrial personal computer is respectively connected with the detection probe and the DDS and is used for receiving the sinusoidal excitation voltage signal and the induced voltage signal and determining the position of the defect of the detected object according to the method.

Optionally, the system further includes:

And the acquisition card is respectively connected with the detection probe, the DDS and the industrial personal computer, is used for acquiring the sinusoidal excitation voltage signal and the induction voltage signal and sending the sinusoidal excitation voltage signal and the induction voltage signal to the industrial personal computer.

optionally, the system further includes:

The V/I converter is respectively connected with the DDS and the detection probe, and is used for converting the sinusoidal excitation voltage signal generated by the DDS into a sinusoidal excitation current signal and sending the sinusoidal excitation current signal to the detection probe so that the detection probe detects a detected object according to the sinusoidal excitation current signal to obtain an induced voltage signal;

and the linear power supply is respectively connected with the V/I converter and the detection probe and is used for supplying electric energy to the V/I converter and the detection probe.

optionally, the system further includes:

And the three-axis scanning platform is respectively connected with the industrial personal computer and the detection probe and is used for driving the detection probe to detect the detected object on the aluminum plate according to a preset scanning path according to the control command sent by the industrial personal computer.

optionally, the detection probe includes:

The eddy current sensor is connected with the V/I converter and used for detecting a measured object according to the sinusoidal excitation current signal to obtain an induced voltage signal;

And the amplifying circuit is connected with the eddy current sensor and the acquisition card respectively and is used for amplifying the induced voltage signal.

according to the specific embodiment provided by the invention, the invention discloses the following technical effects:

the invention discloses a nondestructive testing method and a nondestructive testing system for a multi-frequency excitation eddy current field phase gradient spectrum, wherein the method comprises the steps of firstly, acquiring sinusoidal excitation voltage signals of a tested object under different excitation frequencies and induction voltage signals corresponding to the sinusoidal excitation voltage signals at each point of a plane scanning path; secondly, demodulating the induced voltage signal by using a digital phase-sensitive demodulation technology to obtain a phase value; then, carrying out gradient transformation on the phase values under different excitation frequencies to obtain a phase gradient along the X-axis position direction in a plane; and finally, determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies. The invention is based on the two-dimensional angle, and utilizes the phase gradient to identify the position of the defect in the sample to be measured, thereby further improving the identification accuracy compared with the one-dimensional angle.

Drawings

in order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a flow chart of a nondestructive testing method for multi-frequency excitation eddy current field phase gradient spectrum according to an embodiment of the present invention;

FIG. 2 is a structural diagram of a multi-frequency excitation eddy current field phase gradient spectrum nondestructive testing system according to an embodiment of the invention;

FIG. 3 is a schematic diagram of an eddy current sensor according to an embodiment of the present invention;

FIG. 4 is a schematic plan scan path according to an embodiment of the present invention;

FIG. 5 is a graph of the phase gradient along the X-axis position direction at an excitation frequency of 1Hz in accordance with an embodiment of the present invention;

FIG. 6 is a graph of the phase gradient along the X-axis position direction at an excitation frequency of 2Hz in accordance with an embodiment of the present invention;

FIG. 7 is a graph of the phase gradient along the X-axis position direction at an excitation frequency of 3Hz in accordance with an embodiment of the present invention;

The device comprises a Direct Digital Synthesizer (DDS) 1, a Direct Digital Synthesizer (DDS) 2, a detection probe 3, an industrial personal computer 4, a collection card 5, a V/I converter 6, a linear power supply 7 and a three-axis scanning platform.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.

the invention aims to provide a nondestructive testing method and a nondestructive testing system for a multi-frequency excitation eddy current field phase gradient spectrum, which can accurately identify the position of a defect in a sample to be tested.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Fig. 1 is a flowchart of a nondestructive testing method for a multi-frequency excitation eddy current field phase gradient spectrum according to an embodiment of the present invention, and as shown in fig. 1, the present invention provides a nondestructive testing method for a multi-frequency excitation eddy current field phase gradient spectrum, where the method includes:

Step S1: acquiring sinusoidal excitation voltage signals of a measured object under different excitation frequencies;

step S2: acquiring an induced voltage signal corresponding to the sinusoidal excitation voltage signal at each point of a planar scanning path;

Step S3: demodulating the induced voltage signal by using a digital phase-sensitive demodulation technology to obtain a phase value; the phase value formula is:

wherein phi is a phase value, I is a real part of the induced voltage signal,r is athe imaginary part of the voltage signal should be taken,r (n) is a sinusoidal excitation voltage signal,i (n) is a cosine excitation voltage signal,V_x(n) is an ideal induced voltage signal;k is the variation of the modulus values of the induction voltage signal and the excitation voltage signal, and phi is the variation of the phase angle of the induction voltage signal and the excitation voltage signal; n is 0: N-1, and N is the number of sampling points in a single period.

step S4: carrying out gradient transformation on phase values under different excitation frequencies to obtain a phase gradient along the X-axis position direction in a plane, wherein the specific formula is as follows:

wherein, g_x(X, y) is the phase gradient along the X-axis position direction, and the phase value data is a two-dimensional arrayi-1, 2, … p, j-1, 2, … q, i and j represent different positions in the X-axis direction and the Y-axis direction, respectively.

step S5: determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies; the method specifically comprises the following steps:

step S51: using a 2-dimensional gray filling contour map to draw phase gradients along the X-axis position direction under different excitation frequencies to obtain a phase gradient map;

Step S52: and determining the position of the defect of the measured object according to the phase gradient map.

the invention discloses a nondestructive testing method and a nondestructive testing system for a multi-frequency excitation eddy current field phase gradient spectrum, wherein the method comprises the steps of firstly, acquiring sinusoidal excitation voltage signals of a tested object under different excitation frequencies and induction voltage signals corresponding to the sinusoidal excitation voltage signals at each point of a plane scanning path; secondly, demodulating the induced voltage signal by using a digital phase-sensitive demodulation technology to obtain a phase value; then, carrying out gradient transformation on the phase values under different excitation frequencies to obtain a phase gradient along the X-axis position direction in a plane; and finally, determining the position of the defect of the measured object according to the phase gradient along the X-axis position direction under different excitation frequencies. The invention is based on the two-dimensional angle, and utilizes the phase gradient to identify the position of the defect in the sample to be measured, thereby further improving the identification accuracy compared with the one-dimensional angle.

fig. 2 is a structural diagram of a multi-frequency excitation eddy current field phase gradient spectrum nondestructive testing system according to an embodiment of the present invention, and as shown in fig. 2, the present invention further discloses a multi-frequency excitation eddy current field phase gradient spectrum nondestructive testing system, which includes: the system comprises a direct digital frequency synthesizer DDS1, a detection probe 2 and an industrial personal computer 3;

the direct digital frequency synthesizer DDS1 is used for generating sinusoidal excitation voltage signals under different excitation frequencies; the detection probe 2 is connected with the DDS1 and is used for detecting a detected object according to the sinusoidal excitation voltage signal to obtain an induction voltage signal; the industrial personal computer 3 is respectively connected with the detection probe 2 and the DDS1 and is used for receiving the sinusoidal excitation voltage signal and the induced voltage signal and determining the position of the defect of the detected object according to the method.

as an embodiment, the system of the present invention further includes:

and the acquisition card 4 is respectively connected with the detection probe 2, the DDS1 and the industrial personal computer 3, is used for acquiring the sinusoidal excitation voltage signal and the induction voltage signal, and sends the sinusoidal excitation voltage signal and the induction voltage signal to the industrial personal computer 3.

as an embodiment, the system of the present invention further includes:

the V/I converter 5 is respectively connected with the DDS1 and the detection probe 2, and is used for converting the sinusoidal excitation voltage signal generated by the DDS1 into a sinusoidal excitation current signal and sending the sinusoidal excitation current signal to the detection probe 2, so that the detection probe 2 detects a detected object according to the sinusoidal excitation current signal to obtain an induced voltage signal;

And the linear power supply 6 is respectively connected with the V/I converter 5 and the detection probe 2 and is used for supplying electric energy to the V/I converter 5 and the detection probe 2.

As an embodiment, the system of the present invention further includes:

the three-axis scanning platform 7 is respectively connected with the industrial personal computer 3 and the detection probe 2 and is used for driving the detection probe 2 to detect a detected object on an aluminum plate according to a preset scanning path according to a control instruction sent by the industrial personal computer 3; specifically, the detection probe 2 is fixed below the triaxial scanning platform 7.

As an embodiment, the inspection probe 2 of the present invention includes:

the eddy current sensor is connected with the V/I converter 5 and used for detecting a measured object according to the sinusoidal excitation current signal to obtain an induced voltage signal;

And the amplifying circuit is respectively connected with the eddy current sensor and the acquisition card 4 and is used for amplifying the induced voltage signal.

the invention determines the shape, the size, the plane scanning path and the scanning frequency range of the detection probe 2 according to the material, the shape and the size of a sample to be detected. In the invention, the sample to be measured is tested by taking an aluminum plate as an example, the size of the aluminum plate is 200 multiplied by 2mm, the size of the defect on the aluminum plate is 1 multiplied by 20 multiplied by 0.5mm, and the position of the defect is positioned in the center of the surface of the aluminum plate, so the structural size of the eddy current sensor in the detection probe 2 is determined as shown in figure 3, the plane scanning path is shown in figure 4, the scanning range is 120 multiplied by 60mm, and the excitation frequency range is set to be between 1kHz and 3kHz because the eddy current detection is sensitive to the aluminum plate at the low frequency. FIG. 5 shows a phase gradient diagram along the X-axis position direction when the excitation frequency is 1Hz, and FIG. 6 shows a phase gradient diagram along the X-axis position direction when the excitation frequency is 2 Hz; the phase gradient plot along the X-axis position direction when the excitation frequency is 3Hz is shown in FIG. 7. As can be seen from fig. 5-7, most of the display is gray (the right color level is 0), indicating that the phase value along the position direction has no obvious trend; the left side of the center appears black (right scale is shown at-1), indicating that the phase value is decreasing along this position; the right side of the center appears white (right scale is shown at 1), indicating that the phase value is increasing along the direction of this position. Further analysis shows that the phase value of the signal along the scanning path tends to decrease and then increase, which indicates the existence of a defect.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

the principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.