An elastic wave nondestructive testing system with an excitation device based on an acoustic emission system

Abstract

The present invention discloses an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system. The system comprises a signal excitation module, an acoustic emission module, a signal acquisition module, a signal processing module, and an acoustic emission instrument. The signal excitation module is configured to emit elastic wave signals; the acoustic emission module is configured to receive elastic wave signals; the signal acquisition module is configured to acquire elastic wave signals of a certain modality; and the signal processing module is configured to analyze and process the elastic wave signals acquired by the signal acquisition module. The present invention utilizes an elastic wave emitter to actively generate an elastic wave source. During propagation, the elastic wave generates complex interactions with defects, such as reflection and scattering. Furthermore, the unique high sensitivity of the acoustic emission system is utilized to pick up weak defect signals. Finally, with the aid of algorithms such as image enhancement, defect imaging is achieved, resulting in intuitive imaging results.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure vessel defect detection, and in particular to an elastic wave nondestructive detection system with an excitation device based on an acoustic emission system. Background Art

[0002] Pressure vessels refer to closed equipment that contains gas or liquid and bears a certain pressure. Pressure vessels are prone to defects during the manufacturing process, especially in the weld area, which may produce dangerous defects such as cracks and lack of fusion. They need to be inspected for defects before leaving the factory. Currently, acoustic emission detection technology is mainly used to detect manufacturing defects.

[0003] However, although the existing acoustic emission detection technology has a high detection efficiency, it requires the pressure vessel to be pressurized, thereby using the expansion of defects under pressure load to generate a signal source. This method causes benign defects that originally did not exceed the standard to expand, thereby causing irreversible damage to the pressure vessel. Therefore, an elastic wave non-destructive testing system with an excitation device based on an acoustic emission system is proposed, which can achieve the defect detection effect without damaging the pressure vessel. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that although the existing acoustic emission detection technology has high detection efficiency, the acoustic emission detection requires pressurizing the pressure vessel, thereby utilizing the expansion of defects under pressure load to generate a signal source. This method causes benign defects that originally did not exceed the standard to expand, thereby causing irreversible damage to the pressure vessel. Therefore, an elastic wave non-destructive testing system with an excitation device based on an acoustic emission system is proposed, so that it can truly achieve defect detection effects without damaging the pressure vessel.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An elastic wave nondestructive testing system with an excitation device based on an acoustic emission system, comprising a signal excitation module, an acoustic emission module, a signal acquisition module, a signal processing module, and an acoustic emission instrument;

[0007] The signal excitation module is used to emit elastic wave signals;

[0008] The acoustic emission module is used to receive elastic wave signals;

[0009] The signal acquisition module is used to collect elastic wave signals of a certain mode;

[0010] The signal processing module is used to analyze and process the elastic wave signal collected by the signal collection module;

[0011] Its non-destructive testing system includes the following steps:

[0012] Step 1: Arrange N acoustic emission modules in a circular or square array on a defect-free standard test block to receive elastic wave signals;

[0013] Step 2: Place a signal excitation module at one of the array points to emit elastic wave signals, and align the emission direction of the signal excitation module with the acoustic emission modules numbered 1, 2, ..., N;

[0014] Step 3: Adjust the signal trigger threshold of the acoustic emission instrument to produce the direct waveform of the sensor;

[0015] Step 4: Record and save the collected defect-free elastic wave signals as N reference signals with the numbers s01, s02, ..., s0N;

[0016] Step 5: Arrange the detection sensor array in the same manner on the target object and repeat steps 1 to 4 to acquire N elastic wave signals containing defects, s1, s2, ..., sN, each with a length of L. Perform gain and translation processing on the acquired elastic wave signals containing defects to make them have the same peak amplitude and position as the elastic wave signals without defects.

[0017] Step 6: Subtract the reference signal from the processed defect signal to obtain the pure defect wave signal: sqi = si - s0i;

[0018] Step 7: Divide the target detection area into M*M rectangular areas. Use the left side of each pixel and the coordinate position of the transmitting and receiving sensors, divided by the speed of the elastic wave, to calculate the elastic wave propagation time matrix Mt corresponding to each pixel. Use the elastic wave time propagation matrix to find the corresponding amplitude sq(i) from the corresponding defect signal sq, thereby constructing the pixel matrix IM(x,y)=sq(Mt(xy));

[0019] Step 8: Repeat step 6 to construct a pixel matrix IM for all N signals; superimpose the N IM matrices to obtain a two-dimensional matrix of the defect image, and draw it; use the obtained defect image to identify the defect and measure its position.

[0020] Preferably, the acoustic emission module is a resonant acoustic emission sensor (a fiber grating sensor may also be used), which is based on the piezoelectric effect of crystal elements. When the propagation of stress waves (particle) motion (transverse waves, longitudinal waves, surface waves, etc.) is transmitted to the contact surface of the sensor, it drives the proton movement on the piezoelectric ceramic, thereby producing a compression and stretching effect on the piezoelectric ceramic, which is then converted into a voltage signal and sent to the signal processor to complete the transformation process of the stress wave to the electrical signal wave.

[0021] Furthermore, the signal excitation module includes a signal excitation module and a piezoelectric transducer, and the piezoelectric transducer is connected to the signal excitation module, and the frequency of the signal generator is scanned and set according to a certain frequency range until a single-mode elastic wave signal is obtained.

[0022] Preferably, the signal excitation module uses its circuit to excite the piezoelectric transducer to emit a sine wave with adjustable frequency and period, the frequency adjustment range is 10KHz to 5MHz, and the period condition range is 0.5-10.

[0023] Preferably, the incident angle and incident azimuth of the elastic wave emitted by the transducer are adjustable. The incident angle condition ranges from 0 to 90 degrees according to the thickness of the workpiece; the incident azimuth is adjusted to be aligned with the receiving sensor.

[0024] Preferably, the resonant acoustic emission sensor has a built-in signal gain function, and the gain range is 0-40dB.

[0025] Furthermore, the trigger threshold of the acoustic emission instrument is adjusted to 90% of the maximum amplitude, thereby ensuring that a stable elastic wave signal is received without synchronization.

[0026] As a further solution of the present invention, the signal acquisition module is connected to a signal acquisition display, and the signal acquisition module and the signal acquisition display are both connected to the signal processing module.

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

[0028] (1) Avoid the expansion of active defects caused by pressure, and achieve true non-destructive testing.

[0029] (2) It reduces the number of on-site pressure testing equipment and reduces the investment of manpower and material resources to solve the inspection cost.

[0030] (3) Due to the use of autonomous control of the transmitter waveform, the workload of data analysis is reduced and the interference of a large amount of clutter is avoided.

[0031] (4) Due to the simplification of signal processing, defect imaging can be achieved by using image processing algorithms, and the results are intuitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flowchart of an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system proposed by the present invention;

[0033] Figure 2 This is a sensor array layout diagram of an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system proposed by the present invention;

[0034] Figure 3 This is a schematic diagram of reference signals for an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system proposed by the present invention;

[0035] Figure 4 This is a schematic diagram of defect signals in an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system proposed by the present invention;

[0036] Figure 5 This is a schematic diagram of a pure defect signal of an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system proposed by the present invention;

[0037] Figure 6 This is a schematic diagram of two-dimensional defect imaging of an elastic wave nondestructive testing system with an excitation device based on an acoustic emission system proposed by the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0039] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] Reference Figure 1-6 An elastic wave nondestructive testing system with an excitation device based on an acoustic emission system includes a signal excitation module, an acoustic emission module, a signal acquisition module, a signal processing module, and an acoustic emission instrument; the signal excitation module is used to emit elastic wave signals; the acoustic emission module is used to receive elastic wave signals; the signal acquisition module is used to acquire elastic wave signals of a certain mode; the signal processing module is used to analyze and process the elastic wave signals acquired by the signal acquisition module; the nondestructive testing system includes the following steps:

[0041] Step 1: Arrange N acoustic emission modules in a circular or square array on a defect-free standard test block to receive elastic wave signals;

[0042] Step 2: Place a signal excitation module at one of the array points to emit elastic wave signals, and align the emission direction of the signal excitation module with the acoustic emission modules numbered 1, 2, ..., N;

[0043] Step 3: Adjust the signal trigger threshold of the acoustic emission instrument to produce the direct waveform of the sensor;

[0044] Step 4: Record and save the collected defect-free elastic wave signals as N reference signals with the numbers s01, s02, ..., s0N;

[0045] Step 5: Arrange the detection sensor array in the same manner on the target object and repeat steps 1 to 4 to acquire N elastic wave signals containing defects, s1, s2, ..., sN, each with a length of L. Perform gain and translation processing on the acquired elastic wave signals containing defects to make them have the same peak amplitude and position as the elastic wave signals without defects.

[0046] Step 6: Subtract the reference signal from the processed defect signal to obtain the pure defect wave signal: sqi = si - s0i;

[0047] Step 7: Divide the target detection area into M*M rectangular areas. Use the left side of each pixel and the coordinate position of the transmitting and receiving sensors, divided by the speed of the elastic wave, to calculate the elastic wave propagation time matrix Mt corresponding to each pixel. Use the elastic wave time propagation matrix to find the corresponding amplitude sq(i) from the corresponding defect signal sq, thereby constructing the pixel matrix IM(x,y)=sq(Mt(xy));

[0048] Step 8: Repeat step 6 to construct a pixel matrix IM for all N signals; superimpose the N IM matrices to obtain a two-dimensional matrix of the defect image, and draw it; use the obtained defect image to identify the defect and measure its position.

[0049] In a specific embodiment, the acoustic emission module is a resonant acoustic emission sensor, which is based on the piezoelectric effect of crystal elements. When the propagation of stress waves (particle) motion (transverse waves, longitudinal waves, surface waves, etc.) is transmitted to the contact surface of the sensor, it drives the proton movement on the piezoelectric ceramic, thereby producing compression and stretching effects on the piezoelectric ceramic, which is then converted into a voltage signal and sent to the signal processor to complete the transformation process from stress wave to electrical signal wave. The signal excitation module includes a signal excitation module and a piezoelectric transducer, and the piezoelectric transducer is connected to the signal excitation module. According to a certain frequency range, the frequency of the signal generator is scanned and set until a single modal elastic wave signal is obtained. The signal excitation module uses its circuit to excite the piezoelectric transducer to emit a frequency and period adjustable sine wave. The frequency adjustment range is 10KHz~5MHz, and the period condition range is 0.5~10.

[0050] Furthermore, the incident angle and incident azimuth of the elastic wave emitted by the transducer can be adjusted. Depending on the thickness of the workpiece, the incident angle condition range is 0-90°; the incident azimuth is adjusted to be aligned with the receiving sensor. The resonant acoustic emission sensor has a signal gain function with a gain range of 0-40dB. The trigger threshold of the acoustic emission instrument is adjusted to 90% of the maximum amplitude, thereby ensuring that a stable elastic wave signal is received without the need for synchronization. The signal acquisition module is connected to a signal acquisition display, and the signal acquisition module and the signal acquisition display are both connected to the signal processing module.

[0051] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0052] Working principle: N acoustic emission modules are arranged in a circular or square array on a defect-free standard test block to receive elastic wave signals; a signal excitation module is arranged at one of the array points to emit elastic wave signals, and the emission direction of the signal excitation module is aligned with the acoustic emission modules numbered 1, 2, ..., N; the signal trigger threshold of the acoustic emission instrument is adjusted to produce a direct waveform of the sensor; the collected defect-free elastic wave signals are recorded and saved as N reference signals with the numbers s01, s02, ..., s0N; the detection sensor array is arranged in the same way on the target detection object, and steps 1 to 4 are repeated to collect N defect-containing elastic wave signals s1, s2, ..., sN, each with a signal length of L, and the collected defect-containing elastic wave signals are subjected to gain and translation processing to make them consistent with the defect-containing elastic wave signals. The peak amplitude and position of the defect-free elastic wave signal are the same; the reference signal is subtracted from the processed defect signal to obtain a pure defect wave signal: sqi = si - s0i; the target detection area is divided into M*M rectangular areas, and the left side of each pixel point and the coordinate position of the transmitting and receiving sensors are divided by the speed of the elastic wave to calculate the propagation time matrix Mt of the elastic wave corresponding to each pixel point. The elastic wave time propagation matrix is ​​used to find the corresponding amplitude sq(i) from the corresponding defect signal sq, thereby constructing the pixel matrix IM(x, y) = sq(Mt(xy)); repeat step 6 to construct the pixel matrix IM for all N signals; superimpose the N IM matrices to obtain a two-dimensional matrix of the defect image, and draw it; use the obtained defect image to identify and measure the position of the defect.

Claims

1. An elastic wave nondestructive testing system with an excitation device based on an acoustic emission system, characterized in that: It includes signal excitation module, acoustic emission module, signal acquisition module, signal processing module and acoustic emission instrument; The signal excitation module is used to emit elastic wave signals; The acoustic emission module is used to receive elastic wave signals; The signal acquisition module is used to collect elastic wave signals of a single mode; The signal processing module is used to analyze and process the elastic wave signal collected by the signal collection module; The working principle of the nondestructive testing system includes the following steps: Step 1: Arrange N acoustic emission modules in a circular or square array on a defect-free standard test block to receive elastic wave signals; Step 2: Place a signal excitation module at one of the array points to emit elastic wave signals, and align the emission direction of the signal excitation module with the acoustic emission modules numbered 1, 2, ..., N; Step 3: Adjust the signal trigger threshold of the acoustic emission instrument to produce the direct waveform of the acoustic emission module; Step 4: Record and save the collected defect-free elastic wave signals as N reference signals with the numbers s01, s02, ..., s0N; Step 5: Arrange the acoustic emission module array in the same manner on the target object and repeat steps 1 to 4 to acquire N elastic wave signals containing defects, s1, s2, ..., sN, each with a length of L. Perform gain and translation processing on the acquired elastic wave signals containing defects to make them have the same peak amplitude and position as the elastic wave signals without defects. Step 6: Subtract the reference signal from the processed defect signal to obtain the pure defect wave signal: sqi=si-s0i; Step 7: Divide the target detection area into M*M rectangular areas. Use the coordinates of each pixel point and the coordinate positions of the transmitting and receiving acoustic emission modules, divided by the speed of the elastic wave, to calculate the elastic wave propagation time matrix Mt corresponding to each pixel point. Use the elastic wave time propagation matrix to find the corresponding amplitude sq(i) from the corresponding defect signal sq, thereby constructing the pixel matrix IM(x,y)=sq(Mt(xy)); Step 8: Repeat step 6 to construct a pixel matrix IM for all N signals; superimpose the N IM matrices to obtain a two-dimensional matrix of the defect image, and draw it; use the obtained defect image to identify the defect and measure its position.

2. The elastic wave nondestructive testing system with an excitation device based on an acoustic emission system according to claim 1, characterized in that: The acoustic emission module is a resonant acoustic emission sensor.

3. The elastic wave nondestructive testing system with an excitation device based on an acoustic emission system according to claim 1, characterized in that: The signal excitation module includes a signal generator and a piezoelectric transducer, and the piezoelectric transducer is connected to the signal generator. The frequency of the signal generator is scanned and set according to a certain frequency range until a single-mode elastic wave signal is obtained.

4. The elastic wave nondestructive testing system with an excitation device based on an acoustic emission system according to claim 3, characterized in that: The signal excitation module uses its circuit to excite the piezoelectric transducer to emit a sine wave with adjustable frequency and period, and the frequency adjustment range is 10KHz-5MHz.

5. The elastic wave nondestructive testing system with an excitation device based on an acoustic emission system according to claim 3, characterized in that: The incident angle and incident azimuth of the elastic wave emitted by the piezoelectric transducer are both adjustable. The incident angle can be adjusted in the range of 0-90° according to the thickness of the workpiece; the incident azimuth is adjusted to align with the receiving sensor.

6. The elastic wave nondestructive testing system with an excitation device based on an acoustic emission system according to claim 2, characterized in that: The resonant acoustic emission sensor has a built-in signal gain function with a gain range of 0-40dB.

7. The elastic wave nondestructive testing system with an excitation device based on an acoustic emission system according to claim 1, characterized in that: The signal acquisition module is connected to a signal acquisition display, and both the signal acquisition module and the signal acquisition display are connected to a signal processing module.

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