CN103760243A - Microcrack nondestructive testing device and method - Google Patents

Abstract

The present invention discloses a micro-crack ultrasonic-acoustic emission non-destructive detection device and method, which involves using an ultrasonic emission device to generate an excitation source, and then using acoustic emission technology to detect micro-crack damage in a component, that is: using an ultrasonic emission device to emit an excitation source on the surface of the component, using an acoustic emission acquisition and processing system to collect, amplify and perform signal processing and analysis on the signal, and obtain the nonlinear characteristic parameters of the signal, so as to judge whether the component under test has micro-crack damage and the degree of damage. The device used includes an ultrasonic emission device, an acoustic emission sensor, a preamplifier and an acoustic emission acquisition and analysis system. The present invention combines ultrasonic technology with acoustic emission technology to construct a non-destructive detection system with static defect detection and dynamic defect detection functions, realizes component micro-crack detection, and quickly evaluates the component as a whole, overcoming the shortcomings of the existing acoustic emission method that cannot detect static defects and the ultrasonic detection method that has low detection efficiency and is difficult to capture tiny cracks.

Description

Device and method for non-destructive testing of micro-cracks

technical field

The invention relates to the technical field of non-destructive testing, in particular to a micro-crack non-destructive testing device and method.

Background technique

High-end mechanical equipment components in important industries of the national economy (such as construction machinery, ships, nuclear power, aerospace, etc.) have great utilization value after they are decommissioned once, so their remanufacturing has attracted great attention. Remanufacturing is guided by the theory of the whole life cycle of products, with the goal of leapfrog improvement in the performance of waste products, with high quality, high efficiency, energy saving, material saving, and environmental protection as the criteria, and with advanced technology and industrialized production as means to repair, The general term for a series of technical measures or engineering activities to transform waste products. After the remanufactured blank (waste part) has experienced one or more service cycles, certain damage or defects will appear in its structure, which will become a key element affecting its service life.

Therefore, evaluating the stress state and damage degree of the remanufactured blank is a key problem to be solved before remanufacturing. At present, the inspection process for remanufactured blanks is manual preliminary screening-cleaning-conventional non-destructive testing, but there are a large number of missed inspections in the manual screening process, and the process of cleaning the missed inspection components first and then testing is very labor-intensive; conventional non-destructive testing mainly uses ultrasonic waves method, which is insensitive to the presence of microcracks in the tested component. Due to the extremely complex service conditions of most remanufactured components, detection cannot be performed when the remanufactured components are running, and there is a lack of quantitative damage detection. Therefore, in general, the current detection methods have disadvantages such as high cost, poor reliability, narrow application range, and inability to take into account the dynamic cracks and static cracks of the remanufactured blank at the same time.

Contents of the invention

The object of the present invention is to provide a micro-crack non-destructive testing device and method with high detection efficiency, wide application range, and the detection of dynamic and static remanufactured parts.

The present invention adopts the following technical solutions: a non-destructive testing device for microcracks, including an ultrasonic generator, an ultrasonic probe, and a component to be tested. The ultrasonic generator is connected to the component to be tested through an ultrasonic probe, and also includes an acoustic emission device. The device includes an acoustic emission acquisition and processing system, an acoustic emission sensor connected to the measured component, a preamplifier connected to the acoustic emission acquisition and processing system and the acoustic emission sensor, and the ultrasonic probe is connected to the measured component. A couplant is filled between the acoustic emission sensor and the measured component.

As a further improvement of the present invention:

The ultrasonic probe of the ultrasonic generator is a one-way probe, and the parameters of the ultrasonic probe number and the ultrasonic generator are determined according to the detected object;

The number of channels of the acoustic emission acquisition and analysis system is one or more;

The acoustic emission acquisition and analysis system includes a signal acquisition unit, a signal amplification unit and a signal processing unit;

The coupling agent and the coupling agent are vaseline.

A method for non-destructive detection of microcracks, comprising the following steps:

(1) Determination of key parts to be inspected of components: Determine the key parts to be inspected of components according to the structure of the components to be tested and the accumulation of experience in production practice, the observation of production technicians and theoretical analysis;

(2) Determination of the acoustic emission acquisition and analysis system: determine the number of channels of the acoustic emission acquisition and analysis system and the type of acoustic emission sensor according to the shape, material, detection accuracy and other factors of the measured component; etc. are not the same, so the number of channels required for each component to be tested is also different. In order to meet the detection requirements of different components to be tested or large components, the total number of channels of the acoustic emission testing instrument is generally not less than 16. Determine the frequency range that the sensor needs to monitor according to the characteristics of the material and shape of the part to be inspected, and select the appropriate acoustic emission sensor according to this range. Since the collected signal is generally weak, the collected signal should be amplified by the preamplifier and then sent to the signal processing equipment. At the same time, the preamplifier and other equipment should be placed reasonably to prevent the physical disturbance of the detection equipment during detection. Factors that affect the signal acquisition results, thereby affecting the detection effect;

(3) Determination of the layout of the acoustic emission sensor: determine the layout of the acoustic emission sensor according to the geometric shape and volume of the part to be tested of the component to be tested; in order to achieve a good coupling between the sensor and the surface of the component to be tested, before arranging the sensor Sandpaper and other grinding tools should be used to remove the anti-rust paint on the surface of the component under test or other stains that may affect the signal acquisition results; at the same time, Vaseline should be added as a coupling agent at the contact part between the sensor and the component; When it is irregular, use a special magnetic seat with a plastic groove structure to press and fix the acoustic emission sensor on the surface of the component to prevent the sensor from sliding on the surface of the component and affect the data collection;

(4) Determination of the state of the component under test: determine whether the component under test is static or dynamic; static means that the cracks in the component are in a static state, and dynamic means that the cracks in the component are in an active state;

(5) Detection method when the component under test is static:

a. The ultrasonic generator emits ultrasonic excitation to an appropriate surface of the component to be tested except for the arrangement surface of the acoustic emission sensor, as the analog signal source of the acoustic emission acquisition and analysis system; the ultrasonic probe is a one-way probe, and the ultrasonic probe The number and parameters of the ultrasonic generator are reasonably selected and set according to the shape, complexity, material properties of the detected component, and the frequency range that the acoustic emission sensor can collect;

The excitation part of the ultrasonic signal should be relatively flat, and the anti-rust paint or other stains on the component should be removed to ensure the excitation effect;

b. The acoustic emission sensor collects the signal, which is amplified by the preamplifier and sent to the acoustic emission acquisition and processing system;

计算核矩阵，

计算核矩阵的特征值和特征向量，

由特征值和特征向量计算特征空间主成分并根据需要保留一定贡献率的主成分，

对主成分采用独立分量分析方法进行分离，得到非线性特征参数；波形信号由FFT变换或小波变换等对其进行频域或时频分析得到高次谐波成分的信息作为特征参数，最后综合声发射参数的非线性特征参数和波形信号特征参数组成非线性特征参数向量； c. The Acoustic Emission Acquisition and Analysis System receives signals and analyzes and processes them; because the collected signals include acoustic emission parameters and waveform signals, the signal processing unit also includes two parts. The acoustic emission parameters adopt the nuclear independent component analysis method, and the processing flow is as follows: Data normalization processing,

Compute the kernel matrix,

Compute the eigenvalues and eigenvectors of the kernel matrix,

Calculate the principal components of the feature space from the eigenvalues and eigenvectors and retain the principal components with a certain contribution rate as needed,

The principal components are separated by the independent component analysis method to obtain the nonlinear characteristic parameters; the waveform signal is analyzed by FFT transform or wavelet transform in the frequency domain or time-frequency to obtain the information of the high-order harmonic components as the characteristic parameters, and finally the integrated sound The nonlinear characteristic parameter of the transmission parameter and the characteristic parameter of the waveform signal form a nonlinear characteristic parameter vector;

d. Compare the obtained nonlinear characteristic parameter vector with the nonlinear characteristic parameter vector obtained when the component is intact, and judge whether there are microcracks and the degree of microcrack damage in the tested component;

(6) Detection method when the component under test is dynamic:

a. Directly use the acoustic emission sensor to collect in real time the acoustic emission signal excited by the presence of micro-cracks inside the component under test;

b. After being amplified by the preamplifier, it is sent to the acoustic emission acquisition and analysis system;

数据归一化处理，

计算核矩阵，

计算核矩阵的特征值和特征向量，

由特征值和特征向量计算特征空间主成分并根据需要保留一定贡献率的主成分，

对主成分采用独立分量分析方法进行分离，得到非线性特征参数；波形信号由FFT变换或小波变换等对其进行频域或时频分析得到高次谐波成分的信息作为特征参数，最后综合声发射参数的非线性特征参数和波形信号特征参数组成非线性特征参数向量； c. The acoustic emission acquisition and processing system receives the signal and analyzes and processes the signal; because the collected signal includes acoustic emission parameters and waveform signals, the signal processing unit also includes two parts. The acoustic emission parameters adopt the nuclear independent component analysis method, and the processing flow is as follows:

Data normalization processing,

Compute the kernel matrix,

Compute the eigenvalues and eigenvectors of the kernel matrix,

Calculate the principal components of the feature space from the eigenvalues and eigenvectors and retain the principal components with a certain contribution rate as needed,

The principal components are separated by the independent component analysis method to obtain the nonlinear characteristic parameters; the waveform signal is analyzed by FFT transform or wavelet transform in the frequency domain or time-frequency to obtain the information of the high-order harmonic components as the characteristic parameters, and finally the integrated sound The nonlinear characteristic parameter of the transmission parameter and the characteristic parameter of the waveform signal form a nonlinear characteristic parameter vector;

d. Compare the obtained nonlinear characteristic parameter vector with the nonlinear characteristic parameter obtained when the component is intact, and judge whether there are microcracks and the degree of microcrack damage in the tested component.

Compared with the prior art, the present invention has the advantages of:

1. The non-destructive testing device includes an ultrasonic emission device and an acoustic emission signal acquisition and processing system, which can perform non-destructive testing on dynamic or static components under test, which is easy to use and has a wide range of applications;

2. Obtain the nonlinear characteristic parameter vector of the microcrack of the component under test through the acoustic emission signal processing unit; deduce whether there is a microcrack in the component under test and the damage degree of the microcrack from the nonlinear characteristic parameter vector, and the detection efficiency is high;

3. When the component under test is in a static state, the excitation is emitted by the ultrasonic emitting device as a signal source, which avoids the secondary damage to the component caused by the external mechanical load and the influence of environmental noise.

Description of drawings

FIG. 1 is an overall schematic diagram of the microcrack nondestructive testing device system of the present invention.

Fig. 2 is a layout diagram of the ultrasonic probe and the acoustic emission sensor of the present invention on the surface of the component under test.

Fig. 3 is a flow chart of the non-destructive detection method for microcracks of the present invention.

Fig. 4 is a schematic diagram of constituent units of the acoustic emission analysis and processing system of the present invention.

Fig. 5 is a flow chart of signal processing of a microcrack nondestructive testing device and method according to the present invention.

Fig. 6 is a layout diagram of the ultrasonic probe and the acoustic emission sensor of the present invention on the surface of the water turbine.

Fig. 7 is a flow chart of specific steps for microcrack detection of a water turbine runner according to an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The microcrack nondestructive testing device shown in Figure 1-3 includes an ultrasonic generator 1, an ultrasonic probe 2, and a component under test 3. The ultrasonic generator 1 is connected to the component under test 3 through the ultrasonic probe 2, and also includes an acoustic emission device, The acoustic emission device comprises an acoustic emission acquisition and processing system 6, an acoustic emission sensor 4 connected to the measured component 3, a preamplifier 5 connected to the acoustic emission acquisition and processing system 6 and the acoustic emission sensor 4, the A coupling agent 8 is filled between the ultrasonic probe 2 and the component under test 3 , and a coupling agent 7 is filled between the acoustic emission sensor 4 and the component under test 3 .

Described ultrasonic probe 2 adopts unidirectional probe, and the number of ultrasonic probe 2 and the parameter of ultrasonic generator 1 are determined according to detected object, and in the implementation example as shown in Figure 6, ultrasonic probe 2 is 4, and the center of ultrasonic generator 1 The frequency is 500kHz, the excitation range of emission is 100kHz-1MHz, and the output voltage is 300V.

The number of channels of the acoustic emission acquisition and processing system 6 is one or more, and the number of channels in the implementation example shown in FIG. 6 is 13.

计算核矩阵，

计算核矩阵的特征值和特征向量，

由特征值和特征向量计算特征空间主成分并根据需要保留一定贡献率的主成分，

对主成分采用独立分量分析方法进行分离，得到非线性特征参数；波形信号由FFT变换或小波变换等对其进行频域或时频分析得到高次谐波成分的信息作为特征参数，最后综合声发射参数的非线性特征参数和波形信号特征参数组成非线性特征参数向量。 The acoustic emission acquisition and processing system 6 includes a signal acquisition unit, a signal amplification unit and a signal processing unit. Because the collected signal forms include acoustic emission parameters and waveform signals, the signal processing unit also includes two parts. The acoustic emission parameters adopt the nuclear independent component analysis method, and the processing flow is as follows: Data normalization processing,

Compute the kernel matrix,

Compute the eigenvalues and eigenvectors of the kernel matrix,

Calculate the principal components of the feature space from the eigenvalues and eigenvectors and retain the principal components with a certain contribution rate as needed,

The principal components are separated by the independent component analysis method to obtain the nonlinear characteristic parameters; the waveform signal is analyzed by FFT transform or wavelet transform in the frequency domain or time-frequency to obtain the information of the high-order harmonic components as the characteristic parameters, and finally the integrated sound The nonlinear characteristic parameters of the transmission parameters and the waveform signal characteristic parameters form a nonlinear characteristic parameter vector.

The coupling agent 7 and coupling agent 8 are vaseline.

Below in conjunction with the implementation example shown in Figure 6, a Francis turbine runner will describe a non-destructive detection method for micro-cracks in detail, including the following steps:

(1) Determination of key components to be detected: as shown in Figure 6, the diameter of the Francis turbine runner is 8m, the maximum diameter is 8.6m, the height is 5.19m, and the number of runner blades is 13 (in Figure 6, only Two blades), the material of the runner is stainless steel, according to the accumulation of practical experience, the blade of the turbine runner is an area that is prone to microcracks, so the blade of the turbine is determined as the key detection part in the embodiment;

(2) Determination of the Acoustic Emission Acquisition and Processing System: The acoustic emission system used in the detection of micro-cracks in the Francis turbine runner adopts the American Physical Acoustics Corporation (PAC) PCI-2 system, including 8 PCI-2 channel boards, 18-bit A/ D converter, AE application software AEwin and the signal processing unit developed on its secondary development software. Because the turbine runner has 13 blades, and one sensor is arranged on each blade, the number of acoustic emission channels is selected as 13. In the described embodiment, the acoustic emission sensor is selected WDI type, with a center frequency of 500kHz, and the signal frequency range that can be collected is: 100kHz-1MHz; the signal amplification unit is selected as a 2/4/6 type preamplifier, and the amplification factor is selected as 40dB;

(3) Determination of the layout of the acoustic emission sensor: as shown in the embodiment of Figure 6, for the detection of micro-cracks in the runner of the Francis turbine, the probability of micro-cracks in the blade is relatively high and the surface is flat, so the WDI type acoustic emission sensor is arranged in the On the blades of the turbine runner, and in order to reduce errors, the location of the WDI type acoustic emission sensors on each blade should be roughly consistent. In order to have a good coupling between the WDI acoustic emission sensor and the surface of the turbine runner blade, sandpaper and other grinding tools should be used to remove the anti-rust paint on the surface of the turbine blade or other stains that may affect the signal acquisition results; Vaseline should be added to the contact part of the blade as a coupling agent; at the same time, a special magnetic seat with a plastic groove structure is used to press and fix the WDI acoustic emission sensor on the surface of the turbine runner blade to prevent the sensor from sliding on the blade surface and affect the data collection;

(4) Determination of the state of the component under test: the test of the blades of the water turbine in the embodiment shown in Fig. 6 is carried out under static conditions, that is, the water turbine stops running and no external mechanical load is required. At the lower ring 9 of the turbine runner, the ultrasonic generator emits an ultrasonic excitation with a voltage set to 300V as the acoustic emission analog signal source; the WDI acoustic emission sensor arranged on the turbine blade collects the signal, and passes through the preamplifier After being amplified, it is sent to the acoustic emission acquisition and processing system, and the signal is analyzed and processed according to the process described in Figure 5, and the nonlinear characteristic parameter vector of the obtained acoustic emission signal is obtained. By comparing the standard nonlinear characteristic parameter vectors, it can be judged whether there are microcracks and the degree of microcrack damage in the tested component. 6, because the lower ring 9 is relatively flat, it is selected as the ultrasonic excitation emission part. Since the runner is a symmetrical structure, the four ultrasonic probes 2 are respectively arranged at the ends of the two vertical diameters in the middle of the lower ring 9, and the lower ring 9 of the water turbine The anti-rust paint and other stains on the surface in contact with the ultrasonic probe should be removed to ensure the emission effect. At the same time, Vaseline should be filled between the lower ring 9 of the turbine runner and the probe as a coupling agent;

(5) When the tested part 3 is dynamic, that is, the tested component is in the running state or under the applied load state, the acoustic emission sensor 4 is directly arranged on the component 3 instead of using the ultrasonic excitation emitted by the ultrasonic emitting device as the signal source. It can also judge whether there are microcracks in the tested component 3 and the degree of microcrack damage. The invention can realize the non-destructive detection of the microcracks in the static or dynamic state of the component, and can give an overall evaluation of the microcrack damage of the detected component in one detection, reduces the workload and improves the detection efficiency.

The above embodiments are only examples for illustrating the present invention, and are not intended to limit the present invention. Other changes or changes in different forms can also be made without departing from the guiding spirit and scope of the present invention. The patent protection of the present invention is determined by the scope defined by the claims. 

Claims (7)

1. micro-crack the cannot-harm-detection device, comprise ultrasonic generator 1, ultrasonic probe 2, tested member 3, ultrasonic generator 1 is connected with tested member 3 by ultrasonic probe 2, it is characterized in that: also comprise an acoustic emission device, described acoustic emission device comprises acoustic emission acquisition analysis system 6, the calibrate AE sensor 4 being connected with described tested member 3, the prime amplifier 5 being connected with described calibrate AE sensor 4 with described acoustic emission acquisition analysis system 6, between described ultrasonic probe 2 and described tested member 3, be filled with couplant 8, between described calibrate AE sensor 4 and described tested member 3, be filled with couplant 7.

2. according to a kind of micro-crack the cannot-harm-detection device described in claim 1, it is characterized in that: described ultrasonic probe 2 is unidirectional probe; According to detected object 3, determine the quantity of ultrasonic probe 2 and the parameter of ultrasonic generator 1.

3. according to a kind of micro-crack the cannot-harm-detection device described in claim 2, it is characterized in that: the number of active lanes of described acoustic emission acquisition analysis system 6 be one and more than.

4. according to a kind of micro-crack the cannot-harm-detection device described in claim 3, it is characterized in that: described acoustic emission acquisition analysis system 6 comprises signal gathering unit, signal amplification unit and signal processing unit.

5. according to a kind of micro-crack the cannot-harm-detection device described in claim 4, it is characterized in that: described acoustic emission acquisition analysis system signal processing unit is mainly the processing of composite sound emission parameter and waveform signal, acoustic emission parameters adopts kernel independent component analysis method, and treatment scheme is:

data normalization processing,

calculate nuclear matrix,

calculate nuclear matrix eigenwert and proper vector,

by eigenwert and proper vector calculated characteristics spatial PCA, also retained as required the major component of certain contribution rate, to major component, adopt five steps such as independent component analysis method separates to obtain nonlinear characteristic parameters; The information of higher hamonic wave composition that obtains frequency domain through FFT conversion or wavelet transformation for waveform signal is as characteristic parameter, the last nonlinear characteristic parameters of composite sound emission parameter and the characteristic parameter of waveform signal composition nonlinear characteristic parameters vector.

6. according to a kind of micro-crack the cannot-harm-detection device described in claim 5, it is characterized in that: described couplant 7 and couplant 8 are vaseline.

7. a micro-crack lossless detection method, is characterized in that:

(1) determining of member emphasis position to be detected: according to the structure of tested member 3 and may occur that the information such as crack site determine the emphasis position to be detected of member;

(2) determining of acoustic emission acquisition analysis system 6: determine the number of active lanes of acoustic emission acquisition analysis system 6 and the type of calibrate AE sensor 4 according to factors such as the shape of tested member 3, material, accuracy of detection;

(3) determining of calibrate AE sensor 4 arrangements: according to the arrangement of definite calibrate AE sensors 4 such as the geometric configuration at the position to be detected of tested member 3, volume size;

(4) determining of tested member 3 states: judge that tested member 3 is in static or dynamic; Static state is that the crackle in member remains static, and is dynamically the cracks active state in member;

(5) detection method when tested member 3 is static: a. ultrasonic generator 1 is surface emitting ultrasonic exciting except calibrate AE sensor 4 placement-face in tested member 3 position to be detected, as the simulation signal generator of acoustic emission acquisition analysis system 6; Wherein ultrasonic probe is unidirectional probe, and the parameter of ultrasonic probe number and ultrasonic generator 1 is determined according to detected object;

B. calibrate AE sensor 4 gathers this signal, after prime amplifier 5 amplifies, is sent to acoustic emission acquisition processing system 6; C. acoustic emission acquisition processing system 6 receives signal and signal is carried out to analyzing and processing, obtains the nonlinear characteristic parameters vector of signal; The nonlinear characteristic parameters vector contrast obtaining when d. the nonlinear characteristic parameters obtaining is vectorial and member is intact, judges whether tested member 3 exists the degree of micro-crack and micro-cracks damage;

(6) detection method when tested member 3 is dynamic:

A. directly with calibrate AE sensor 4 Real-time Collections because of the acoustic emission signal of tested member 3 inside because existing micro-crack to inspire; B. after amplifying, prime amplifier 5 is sent to acoustic emission acquisition processing system 6;

C. acoustic emission acquisition processing system 6 receives signal analyzing and processing, obtains the nonlinear characteristic parameters vector of signal;

The nonlinear characteristic parameters vector contrast obtaining when d. the nonlinear characteristic parameters obtaining is vectorial and member is intact, judges whether tested member 3 exists the degree of micro-crack and micro-cracks damage.

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