A nondestructive testing device and method based on magnetic memory

Abstract

The application provides a kind of nondestructive testing device based on magnetic memory, belongs to nondestructive testing technical field.Its technical scheme is: including two three-axis magnetic probes capable of collecting three-axis component magnetic signals, the interval of two three-axis magnetic probes can be adjusted;It also includes a conditioning module for filtering and isolating the probe signal and inputting to the acquisition module, the acquisition module can realize multi-channel synchronous acquisition and send the isolated signal to the main control module after analog-to-digital conversion, the main control module is used for processing, analyzing, storing and displaying the signal after analog-to-digital conversion through the user interaction module;It also includes a power module that provides different power supply voltages for the main control module, user interaction module, acquisition module and conditioning module.The beneficial effects of the application are: using magnetic memory testing technology to qualitatively analyze material stress, and using experimental method to match material stress with actual defects to realize nondestructive testing.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a nondestructive testing device and method based on magnetic memory. Background Technology

[0002] Metal magnetic memory is a novel non-destructive testing technique that primarily determines the presence and location of stress concentrations, corrosion defects, and other structural defects in ferromagnetic materials by detecting and analyzing changes in the leakage magnetic field on the material's surface. Developing a pipeline magnetic memory testing device based on magnetic memory is of great significance for the safety performance testing of petrochemical pipelines and the prevention of safety accidents. Summary of the Invention

[0003] The purpose of this invention is to provide a device and a testing method that uses magnetic memory detection technology to qualitatively analyze material stress and uses experimental methods to match material stress with actual defects to achieve non-destructive testing.

[0004] The present invention is achieved through the following measures: a non-destructive testing device based on magnetic memory, characterized in that it includes two triaxial magnetic probes capable of acquiring magnetic signals of three-axis components, and the distance between the two triaxial magnetic probes is adjustable;

[0005] It also includes a conditioning module for filtering and isolating probe signals before inputting them into the acquisition module. The acquisition module can achieve multi-channel synchronous acquisition and convert the isolated signals from analog to digital before sending them to the main control module. The main control module is used to process, analyze, and store the converted signals and display them through the user interaction module.

[0006] It also includes power supply modules that provide different power supply voltages to the main control module, user interaction module, acquisition module and conditioning module.

[0007] The conditioning module includes a first-order RC filter circuit and an OPA2189 operational amplifier chip to form a voltage follower circuit.

[0008] The acquisition module includes an A / D conversion circuit. A resistor is connected in series between the signal terminal of the input channel of the A / D conversion circuit and its corresponding signal ground terminal, and a capacitor is connected in parallel between the signal terminal of the input channel of the A / D conversion circuit and its corresponding signal ground terminal.

[0009] A nondestructive testing method using a magnetic memory-based nondestructive testing device, characterized by the following specific steps:

[0010] S1. Place two triaxial magnetic probes directly above the magnetic component to be tested, and both are parallel to the magnetic component to be tested.

[0011] S2. Adjust the probe position so that the positive z-axis of the two triaxial magnetic probes points to the ground and the positive y-axis is consistent with the detection travel direction;

[0012] S3. Maintain a gap between the two triaxial magnetic probes and determine the vertical distance between the two triaxial magnetic probes based on the magnetic parameters of the magnetic component to be tested.

[0013] S4. Two triaxial magnetic probes move at a constant speed along the axis of the magnetic component under test, and record the measurement values ​​of the two triaxial magnetic probes in real time. The lower triaxial magnetic probe measures the superposition value of the leakage magnetic signal and the geomagnetic field signal of the magnetic component under test, while the upper triaxial magnetic probe measures the geomagnetic field signal.

[0014] S5. The difference waveform is formed by subtracting the data waveforms obtained from the two triaxial magnetic probes; the difference waveform is the leakage magnetic signal of the magnetic component under test.

[0015] S6. Filter the difference waveform;

[0016] S7. Calculate the vector sum of the filtered data, and then process it using the peak-valley algorithm to obtain the resulting waveform;

[0017] S8. Determine the location of the defect based on the fluctuation amplitude of the resulting waveform.

[0018] The vertical distance between the two triaxial magnetic probes is determined according to the following formula:

[0019]

[0020] In the formula: L is the length of the magnetic component to be tested, mm; W is the width of the magnetic component to be tested, mm; H is the thickness of the magnetic component to be tested, mm; x is the vertical distance between the three-axis magnetic probes, mm; Br is the remanence of the magnetic component to be tested, Gs; B is the magnetic induction intensity of the magnetic component to be tested, Gs.

[0021] To ensure that the difference between the measurements from the two probes represents the leakage magnetic signal of the magnetic component under test, it is necessary to ensure that the upper probe only measures the magnetic induction intensity signal of the Earth's magnetic field. According to Gauss's law, the magnetic induction intensity of a permanent magnet is inversely proportional to the distance. If the magnetic component under test is approximated as a magnetic dipole, with dipole moment M, distance r between the observation point and the magnet, and angle s between the dipole moments, then:

[0022]

[0023]

[0024]

[0025] Where μ is the permeability constant in vacuum, and its magnitude is:

[0026] μ=4π×10 -7 (4)

[0027] By combining the three magnetic field vectors, we can obtain:

[0028]

[0029] By combining equations (1)(2)(3)(4)(5) and treating the pipe as a uniform cubic permanent magnet, the relationship between the magnetic induction intensity at a point on the pipe and the pipe itself can be obtained. This relationship can then be used to determine the distance between probes S1 and S2.

[0030]

[0031] In the formula: L is the length of the permanent magnet, mm; W is the width of the permanent magnet, mm; H is the thickness of the permanent magnet, mm; x is the distance, mm; Br is the remanence of the permanent magnet, Gs; B is the magnetic induction intensity, Gs.

[0032] The method for measuring the remanence of the magnetic component under test is as follows: sampling points are set at 5cm intervals on the magnetic component under test, and the radial magnetic field of the sampling points is measured. The vector sum of the average values ​​of each sampling point is the remanence of the magnetic component under test. Other parameters can be measured using existing technologies.

[0033] Compared with the prior art, the beneficial effects of the present invention are: a device and detection method that uses magnetic memory detection technology to qualitatively analyze material stress and uses experimental methods to match material stress with actual defects to achieve non-destructive testing. Attached Figure Description

[0034] Figure 1 This is a structural block diagram of the present invention.

[0035] Figure 2 Design a block diagram for the power module circuit.

[0036] Figure 3 This is the power supply circuit for the conditioning module.

[0037] Figure 4 Power supply circuit for the user interaction module.

[0038] Figure 5 This is the power supply circuit for the main control module.

[0039] Figure 6 This is the power supply circuit for the data acquisition module.

[0040] Figure 7 Design a block diagram for the conditioning and data acquisition module.

[0041] Figure 8 This is a schematic diagram of a first-order RC filter circuit.

[0042] Figure 9 This is a schematic diagram of a voltage follower circuit.

[0043] Figure 10 This is a functional block diagram of AD7608.

[0044] Figure 11 This is a schematic diagram of the AD7608 analog input circuit.

[0045] Figure 12 This is a diagram of the input resistance matching structure for the analog input terminal.

[0046] Figure 13 This is a block diagram of the peripheral circuit design for the main control module.

[0047] Figure 14 This refers to the peripheral circuitry of the chip.

[0048] Figure 15 The image shows the waveform of the triaxial magnetic field data acquired by the lower triaxial magnetic probe.

[0049] Figure 16 This is a waveform diagram of geomagnetic signal data collected by the upper triaxial magnetic probe.

[0050] Figure 17 This is a waveform diagram of the difference.

[0051] Figure 18 This is the waveform after filtering.

[0052] Figure 19 The result is a waveform diagram. Detailed Implementation

[0053] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0054] Example 1:

[0055] See Figure 1 A non-destructive testing device based on magnetic memory, characterized in that it includes two triaxial magnetic probes capable of acquiring triaxial magnetic signals, and the distance between the two triaxial magnetic probes is adjustable.

[0056] It also includes a conditioning module for filtering and isolating probe signals before inputting them into the acquisition module. The acquisition module can achieve multi-channel synchronous acquisition and convert the isolated signals from analog to digital before sending them to the main control module. The main control module is used to process, analyze, and store the converted signals and display them through the user interaction module.

[0057] It also includes power supply modules that provide different power supply voltages to the main control module, user interaction module, acquisition module and conditioning module.

[0058] The conditioning module includes a first-order RC filter circuit and an OPA2189 operational amplifier chip to form a voltage follower circuit.

[0059] The acquisition module includes a resistor connected in series with the analog input channel for analog input impedance matching.

[0060] A nondestructive testing method using a magnetic memory-based nondestructive testing device, characterized by the following specific steps:

[0061] S1. Place two triaxial magnetic probes directly above the magnetic component to be tested, and both are parallel to the magnetic component to be tested.

[0062] S2. Adjust the probe position so that the positive z-axis of the two triaxial magnetic probes points to the ground and the positive y-axis is consistent with the detection travel direction;

[0063] S3. Maintain a gap between the two triaxial magnetic probes and determine the vertical distance between the two triaxial magnetic probes based on the magnetic parameters of the magnetic component to be tested.

[0064] S4. Two triaxial magnetic probes move at a constant speed along the axis of the magnetic component under test, and record the measurement values ​​of the two triaxial magnetic probes in real time. The lower triaxial magnetic probe measures the superposition value of the leakage magnetic signal and the geomagnetic field signal of the magnetic component under test, while the upper triaxial magnetic probe measures the geomagnetic field signal.

[0065] S5. The difference waveform is formed by subtracting the data waveforms obtained from the two triaxial magnetic probes; the difference waveform is the leakage magnetic signal of the magnetic component under test.

[0066] S6. Filter the difference waveform;

[0067] S7. Calculate the vector sum of the filtered data, and then process it using the peak-valley algorithm to obtain the resulting waveform;

[0068] S8. Determine the location of the defect based on the fluctuation amplitude of the resulting waveform.

[0069] The vertical distance between the two triaxial magnetic probes is determined according to the following formula:

[0070]

[0071] In the formula: L is the length of the magnetic component to be tested, mm; W is the width of the magnetic component to be tested, mm; H is the thickness of the magnetic component to be tested, mm; x is the vertical distance between the three-axis magnetic probes, mm; Br is the remanence of the magnetic component to be tested, Gs; B is the magnetic induction intensity of the magnetic component to be tested, Gs.

[0072] To ensure that the difference between the measurements from the two probes represents the leakage magnetic signal of the magnetic component under test, it is necessary to ensure that the upper probe only measures the magnetic induction intensity signal of the Earth's magnetic field. According to Gauss's law, the magnetic induction intensity of a permanent magnet is inversely proportional to the distance. If the magnetic component under test is approximated as a magnetic dipole, with dipole moment M, distance r between the observation point and the magnet, and angle s between the dipole moments, then:

[0073]

[0074]

[0075]

[0076] Where μ is the permeability constant in vacuum, and its magnitude is:

[0077] μ=4π×10 -7 (4)

[0078] By combining the three magnetic field vectors, we can obtain:

[0079]

[0080] By combining equations (1)(2)(3)(4)(5) and treating the pipe as a uniform cubic permanent magnet, the relationship between the magnetic induction intensity at a point on the pipe and the pipe itself can be obtained. This relationship can then be used to determine the distance between probes S1 and S2.

[0081]

[0082] In the formula: L is the length of the permanent magnet, mm; W is the width of the permanent magnet, mm; H is the thickness of the permanent magnet, mm; x is the distance, mm; Br is the remanence of the permanent magnet, Gs; B is the magnetic induction intensity, Gs.

[0083] The method for measuring the remanence of the magnetic component under test is as follows: sampling points are set at 5cm intervals on the magnetic component under test, and the radial magnetic field of the sampling points is measured. The vector sum of the average values ​​of each sampling point is the remanence of the magnetic component under test. Other parameters can be measured using existing technologies.

[0084] Example 2:

[0085] Based on Example 1:

[0086] This application requires the calculation of the magnetic induction intensity gradient in three directions above the magnetic component to be tested during magnetic testing. The abnormal magnetic pipe section is identified by qualitative and quantitative analysis of the two measurement signals, and the location of damage or defect is finally determined. Therefore, the three-axis magnetic probe can be the Mag-690 model.

[0087] For power supply modules, multiple parameters need to be considered, such as the withstand voltage and power rating of components. Specifically, a 14.8V lithium battery can be used to power designated devices. Figure 2 As shown;

[0088] (1) The 14.8V lithium battery is stepped down to ±12V by the MORNSUN DC-DC isolated power supply to power the conditioning module, such as... Figure 3 As shown;

[0089] (2) Because the embedded serial port screen used in the user interaction module has high power consumption and large current, the LM2596DC-DC voltage regulator chip is selected to step down the +12V of the isolated power supply to 5V. Figure 4 As shown; simultaneously, the AMS1117-3.3 LDO regulator chip is used to further step down the voltage to power the main control module. The specific power supply circuit is as follows. Figure 5 As shown.

[0090] (3) The A / D conversion circuit of the acquisition module can be replaced by an A / D chip, generally an 18-bit high-precision chip. Therefore, the power supply section of the A / D chip uses the LDO chip LM2940, which has good stability, fast load response, and low noise. The power supply circuit of the acquisition module is as follows: Figure 6 As shown.

[0091] For the conditioning module and the acquisition module:

[0092] The block diagram of the probe signal conditioning module and the multi-channel signal acquisition module is as follows: Figure 7 As shown, the probe signal conditioning module isolates and filters the analog signal output by the probe. Before being input to the A / D chip of the acquisition module, impedance matching is performed, which greatly reduces interference and errors. Finally, the acquired signal is converted into a digital signal by the A / D chip.

[0093] The voltage follower circuit, consisting of the first-order RC filter circuit of the conditioning module and the OPA2189 operational amplifier chip, is specifically as follows: Figure 8 and Figure 9 As shown.

[0094] For the data acquisition module, the 8-channel DAS chip AD7608 can be used for analog-to-digital conversion. The functional block diagram of AD7608 is shown below. Figure 10 As shown.

[0095] For impedance matching: The analog inputs of the acquisition module all include clamping protection circuits. These clamping protection resistors have relatively large resistance values. When the front-end circuit is connected to the A / D chip, impedance matching between the front-end circuit and the A / D chip is necessary for signal stability. Therefore, a resistor is connected in series between the signal terminal of the A / D chip's input channel and its corresponding signal ground terminal, and a capacitor is connected in parallel between the signal terminal of the A / D chip's input and its corresponding signal ground terminal. Specifically... Figure 11 and Figure 12 As shown.

[0096] The AD7608 chip is a high-precision A / D converter chip and a core component for signal acquisition in this system design. Therefore, the design of its peripheral circuitry is particularly important. Specifically, as follows... Figure 14 As shown. Wherein:

[0097] ① Chip power supply design. The chip uses a single +5V power supply. The 12V output from the lithium battery is regulated by an isolated DC-DC converter and then regulated by a separate LDO chip to output 5V. This output is isolated from the digital ground.

[0098] ② Decoupling and filtering circuit design. The device has four AVCC power supply pins. Each of these four power supply pins uses a 100nF decoupling capacitor, and a 10μF filtering capacitor is used on the power supply side.

[0099] ③ Mode Configuration Circuit Design. The VDRIVE power supply needs to be connected to the same power supply that powers the processor, i.e., connected to the +3.3V power supply of the STM32 main controller, to determine the voltage source of the output logic signal; the AD7608 can operate under both internal reference voltage and externally applied reference voltage. In this system, the REF_SELECT pin is pulled high to configure it to operate under the internal reference voltage; the analog input range setting pin brings out the RANGE pin and pulls it high or low with a jumper cap to change its analog input range. If the approximate range of the signal input can be determined in subsequent work, the state of this pin can be fixed; the digital filter oversampling ratio is controlled by the oversampling pin OS[2:0]. For the convenience of subsequent development, this design connects it to the GPIO port of the STM32 to adjust it according to requirements.

[0100] ④ Communication circuit design. The AD7608 provides two communication interfaces: a parallel interface and a serial interface.

[0101] For the main control module: The main control chip used is the STM32F103RCT6. It features 3 hardware SPI interfaces, 5 hardware serial ports, 3 12-bit ADC interfaces, 51 GPIO ports, and other peripherals. This chip offers strong expandability, high programming flexibility, and cost-effectiveness, meeting all product design requirements. The main control module design block diagram is shown below. Figure 13As shown in the diagram. The MCU receives user commands via buttons, communicates with the A / D chip using the SPI communication protocol to obtain the converted signal data, and then transmits the data to the embedded serial port screen for further processing and operation via serial communication. Simultaneously, it collects battery voltage and displays it on the screen in real time. The wireless pass-through WIFI module and GPS are reserved modules for future system optimization and upgrades.

[0102] The power supply module, conditioning module, acquisition module, and main control module are integrated on the PCB board, which optimizes the hardware of the entire project. In the PCB design, the power supply circuit and peripheral circuit of the AD7608 chip, which is responsible for converting analog signals into digital signals, are one of the key and difficult points of the circuit design. In this part of the design, it is necessary to ensure that the waveform of the power supply voltage is clean and stable, and to pay attention to keeping the switching power supply devices away from the chip. The digital ground and analog ground are grounded at a single point near the chip. At the same time, the chip datasheet is strictly followed when designing the arrangement of filter capacitors, the routing of digital and analog signals, and the copper pouring of power supply, so as to ensure the reliability, stability and high precision requirements of the circuit to the greatest extent.

[0103] Example 3:

[0104] According to the apparatus and method of Embodiment 2 or Embodiment 3, a pipe with a length of 5m and an outer diameter of 18cm is measured. The measuring personnel move the measuring device at a constant speed, and the equipment simultaneously collects and records the magnetic induction intensity data in the x, y, and z directions. The moving speed is approximately 4m / min, and the sampling frequency is 20Hz. The final result is... Figures 15-19 The waveform diagram.

[0105] As can be seen from the figure, the waveform of the vector sum has multiple peaks and valleys. The location of the defect will cause large fluctuations or sudden changes in the magnetic signal. Therefore, the peaks and valleys are the locations of the defects.

[0106] Furthermore, since the data may contain two peaks or valleys that are very close together, but in actual pipelines, this is only the same defect, this function is prone to counting them as two, leading to misjudgment. Therefore, it is necessary to add "MinProminence" to the function to specify a minimum relative height difference requirement, so that only the most prominent maximum / minimum value in the data is calculated. According to testing, specifying a relative height difference of 0.05 reduces the likelihood of misjudgment.

[0107] According to actual verification, the location of the measured defect is basically consistent with the location of the actual defect.

[0108] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0109] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0110] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0111] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A nondestructive testing method based on a magnetic memory nondestructive testing device, characterized in that, The non-destructive testing device includes two triaxial magnetic probes capable of acquiring triaxial magnetic signals, and the distance between the two triaxial magnetic probes is adjustable; It also includes a conditioning module for filtering and isolating probe signals before inputting them into the acquisition module. The acquisition module can achieve multi-channel synchronous acquisition and convert the isolated signals from analog to digital before sending them to the main control module. The main control module is used to process, analyze, and store the converted signals and display them through the user interaction module. It also includes power supply modules that provide different power supply voltages to the main control module, user interaction module, acquisition module and conditioning module; The specific steps of the non-destructive testing method are as follows: S1. Place two triaxial magnetic probes directly above the magnetic component to be tested, and both are parallel to the magnetic component to be tested. S2. Adjust the probe position so that the positive z-axis of the two triaxial magnetic probes points to the ground and the positive y-axis is consistent with the detection travel direction; S3. Maintain a gap between the two triaxial magnetic probes and determine the vertical distance between the two triaxial magnetic probes based on the magnetic parameters of the magnetic component to be tested. S4. Two triaxial magnetic probes move at a constant speed along the axis of the magnetic component to be measured, and the measurement values ​​of the two triaxial magnetic probes are recorded in real time. S5. Calculate the difference waveform by subtracting the data waveforms obtained from the two triaxial magnetic probes; S6. Filter the difference waveform; S7. Calculate the vector sum of the filtered data, and then process it using the peak-valley algorithm to obtain the resulting waveform; S8. Determine the defect location based on the fluctuation amplitude of the resulting waveform; The vertical distance between the two triaxial magnetic probes is determined according to the following formula: Where: L is the length of the magnetic component to be tested, mm; W is the width of the magnetic component to be tested, mm; H is the thickness of the magnetic component to be tested, mm; x is the vertical distance between the three-axis magnetic probes, mm; Br is the remanence of the magnetic component to be tested, Gs; B is the magnetic induction intensity of the magnetic component to be tested, Gs. The method for measuring the remanence of the magnetic component under test is as follows: sampling points are set at 5cm intervals on the magnetic component under test, the radial magnetic field of the sampling points is measured, and the vector sum is obtained by averaging the values ​​of each sampling point, which is the remanence of the magnetic component under test.

2. The nondestructive testing method according to claim 1, characterized in that, The conditioning module includes a first-order RC filter circuit and an OPA2189 operational amplifier chip to form a voltage follower circuit.

3. The nondestructive testing method according to claim 2, characterized in that, The acquisition module includes an A / D conversion circuit. A resistor is connected in series between the signal terminal of the input channel of the A / D conversion circuit and its corresponding signal ground terminal, and a capacitor is connected in parallel between the signal terminal of the input channel of the A / D conversion circuit and its corresponding signal ground terminal.

4. The nondestructive testing method according to claim 1, characterized in that, The user interaction module includes an embedded serial port screen.

5. The nondestructive testing method according to claim 2, characterized in that, A DC path resistor is connected in series in the input loop of the first-order RC filter circuit.

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