A quantitative evaluation method of surface crack defects of metal material surface by broadband ultrasonic surface wave

Abstract

The application discloses a kind of wideband ultrasonic surface wave quantitative evaluation method of surface crack of metal material.The wideband ultrasonic surface wave sensor is applied to the surface wave detection of metal material containing surface crack, the wideband surface wave signal is obtained by detection, the action law of different frequency component ultrasonic surface wave and different length crack defect is analyzed, the ultrasonic characteristic parameter of different frequency component is extracted from wideband surface wave signal, the mapping model of ultrasonic characteristic parameter and metal material surface crack defect information is constructed, and the crack defect is quantitatively evaluated using ultrasonic characteristic parameter.The wideband surface wave evaluation method is applied to the quantitative evaluation of surface crack of metal material in the application, and the crack defect is evaluated using the ultrasonic characteristic parameter of different frequency component in wideband ultrasonic surface wave, which improves the quantitative evaluation ability of surface crack defect of metal material, and has great application value in nondestructive testing and structural health monitoring field.

Description

Technical Field

[0001] This invention relates to a broadband ultrasonic surface wave quantitative evaluation method for surface crack defects in metallic materials, belonging to the field of nondestructive testing and evaluation. Broadband ultrasonic surface waves are generated using a broadband ultrasonic surface sensor. The interaction between ultrasonic surface waves of different frequency components and surface crack defects is analyzed. Ultrasonic characteristic parameters of different frequency components of the broadband ultrasonic surface waves are extracted, and a mapping relationship between different frequency ultrasonic characteristic parameters and surface crack defect information is established. This allows for the broadband ultrasonic surface wave quantitative evaluation of surface crack defects in metallic materials. Background Technology

[0002] Metallic materials are widely used in critical components of thermal power, nuclear power, and other thermoelectric industries. These components operate under harsh environments such as high temperature and high pressure, causing continuous changes in the microstructure of the metallic materials. Under these sustained and complex conditions, cracks easily appear on the surface of the metallic materials. Further growth of these cracks can seriously threaten the service life and structural safety of these critical components. Therefore, quantitatively evaluating the length of surface cracks in critical components using non-destructive testing methods is essential and of great significance for ensuring the safe operation of these metal components.

[0003] Currently, most ultrasonic testing methods for surface cracks in metallic materials employ single-frequency surface ultrasonic waves. Surface ultrasonic waves are generated by the superposition of longitudinal and transverse waves under certain conditions. They can propagate along the surface of metallic materials, and their energy is concentrated within the wavelength depth, rapidly attenuating with increasing depth. When a single-frequency surface ultrasonic wave propagates along the surface and comes into contact with a crack, it undergoes reflection, refraction, and diffraction. By extracting ultrasonic characteristic parameters such as amplitude, time of flight, acoustic attenuation coefficient, and transmission / reflection coefficient from the time-domain signal of the surface ultrasonic wave, quantitative evaluation of surface cracks in metallic materials can be achieved. Furthermore, analyzing the surface wave spectrum and studying its spectral changes under different crack lengths, extracting parameters such as peak frequency, can also provide a quantitative evaluation of surface cracks in metallic materials.

[0004] In the quantitative evaluation of surface cracks in metallic materials, the length of cracks can be evaluated by analyzing the interaction between ultrasonic surface waves and cracks and extracting ultrasonic parameters from the detection signal. However, ultrasonic surface waves with a single excitation frequency can only detect surface cracks within the wavelength depth corresponding to that frequency. When the crack length exceeds the wavelength depth corresponding to the excitation signal frequency, the detection capability of ultrasonic surface waves for surface cracks in metallic materials is limited, requiring the use of lower frequency surface waves. However, the wavelength of surface waves is inversely proportional to the sensitivity of the detection signal; the longer wavelength of low-frequency surface waves also affects their ability to detect cracks. In summary, the frequency information contained in current single-frequency ultrasonic surface waves is limited and cannot fully meet the evaluation requirements for surface cracks in metallic materials. Therefore, there is an urgent need to develop a broadband surface wave quantitative evaluation method for surface crack defects in metallic materials. This method would utilize the rich frequency information components in broadband ultrasonic surface waves, combined with time-frequency analysis of broadband ultrasonic surface wave signals, to analyze the interaction between ultrasonic surface waves of different frequency components and surface crack defects. Ultrasonic characteristic parameters at different frequencies would be extracted, and a mapping relationship between ultrasonic parameters at different frequencies and surface crack defect information would be established, thereby realizing broadband ultrasonic surface wave quantitative evaluation of surface crack defects in metallic materials.

[0005] This invention utilizes a broadband surface wave excitation sensor to excite broadband ultrasonic surface waves at one end of a crack defect in a metallic material. At the other end of the crack defect, a broadband surface wave receiving sensor receives the transmitted ultrasonic surface wave signal after interaction with the crack. Based on time-frequency analysis, the interaction between ultrasonic surface waves of different frequency components and crack defects of different lengths is analyzed. Ultrasonic characteristic parameters of different frequency components in the broadband ultrasonic surface wave are extracted for quantitative evaluation of surface crack defects, solving the problem of limited evaluation capability of single-frequency ultrasonic surface waves. Quantitative evaluation of surface crack defects in metallic materials using broadband ultrasonic surface waves has not been reported domestically or internationally. Summary of the Invention

[0006] This invention aims to develop a broadband ultrasonic surface wave quantitative evaluation method for surface crack defects in metallic materials, addressing the limitation of single-frequency surface wave evaluation capabilities. The proposed broadband surface wave quantitative evaluation method can improve the quantitative evaluation capability of surface crack defects in metallic materials.

[0007] To achieve the above objectives, the present invention adopts the following design scheme:

[0008] A broadband ultrasonic surface wave signal is generated using a broadband excitation sensor. This broadband signal, compared to a single-frequency narrowband signal, is a linearly modulated signal, and its frequency range can be selected from a lower limit of 100kHz to an upper limit of 10MHz, depending on the specific detection object and accuracy. A broadband receiving sensor is used to receive the broadband ultrasonic surface wave signals after interaction with surface crack defects of different lengths. The interaction law between ultrasonic surface waves of different frequency components and crack defects of different lengths is analyzed using time-frequency analysis methods. Ultrasonic characteristic parameters of different frequency components are extracted. A mapping relationship is established between the ultrasonic characteristic parameters of different frequency components and the information of surface crack defects in metallic materials, realizing a broadband ultrasonic surface wave quantitative evaluation of surface crack defects.

[0009] The sensor generates a broadband ultrasonic surface wave signal, characterized in that: the surface wave signal is a broadband signal, containing rich frequency component information including the lower limit frequency to the upper limit frequency.

[0010] The aforementioned ultrasonic surface wave transmission signal time-frequency analysis diagram is characterized by: obtaining the changing trends of ultrasonic propagation characteristics such as signal arrival time and amplitude of ultrasonic surface waves with different frequency components under surface crack defects of different lengths, and describing the interaction law between different frequency components of broadband ultrasonic surface wave signals and surface crack defects after interaction with surface crack defects.

[0011] The broadband ultrasonic surface wave signal characteristic parameters are characterized in that: the characteristic parameters include parameters such as the flight time and amplitude of ultrasonic surface wave signals at different frequencies.

[0012] The method for establishing the relationship between ultrasonic characteristic parameters and surface crack defect information of metallic materials is characterized by the fact that there is an indirect mapping relationship between the characteristic parameters and the crack defect information.

[0013] The broadband ultrasonic surface wave quantitative evaluation of surface crack defects is characterized by: based on the mapping relationship, using broadband ultrasonic characteristic parameters as multivariate independent variables and the length of surface crack defects of metallic materials as dependent variables, performing multivariate linear regression analysis, and calculating the regression coefficients and the sum of squared deviations.

[0014] The present invention can achieve the following effects:

[0015] 1. Broadband ultrasonic surface wave signals are obtained by using a broadband sensor for excitation;

[0016] 2. Broadband ultrasonic surface waves contain multi-frequency component information;

[0017] 3. Based on time-frequency analysis, the interaction between different frequency components of surface wave signals and cracks of different lengths after interaction with crack defects is obtained;

[0018] 4. Extract ultrasonic characteristic parameters of different frequency components of broadband ultrasonic surface wave signals;

[0019] 5. Quantitatively evaluate surface crack defects of different lengths using ultrasonic characteristic parameters of different frequency components;

[0020] 6. Based on broadband ultrasonic surface waves, quantitative evaluation of surface crack defects in metallic materials is achieved, which improves the evaluation capability of surface crack defects in metallic materials. Attached Figure Description

[0021] Figure 1 Schematic diagram of surface cracks and defects in metallic materials;

[0022] Figure 2 An experimental system for detecting surface cracks and defects in metallic materials using broadband sensors;

[0023] Figure 3 Broadband surface wave signal without crack defects and time-frequency analysis diagram;

[0024] Figure 4 Broadband ultrasonic surface waves of crack defects of different lengths

[0025] Figure 5 A schematic diagram of time-frequency analysis of broadband surface wave transmission signals from cracks of different lengths;

[0026] Figure 6 Schematic diagram of quantitative evaluation model for ultrasound characteristic parameters

[0027] Figure 7 A schematic diagram of quantitative evaluation of surface crack defects in metallic materials.

[0028] Figure 2 The components include: 1. Metal material samples with surface crack defects; 2. Wideband ultrasonic surface wave excitation sensor; 3. Wideband surface wave receiving sensor; 4. Function generator (providing wideband excitation signal); 5. Function generator (providing gating signal); 6. High-energy pulse excitation receiving device; 7. Digital oscilloscope. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0030] Step 1: Processing surface cracks and defects in metallic material samples.

[0031] Metal plate specimens with a thickness much greater than the surface wave wavelength were prepared. Open cracks perpendicular to the surface were machined using wire cutting to obtain metal specimens containing cracks of varying depths, such as... Figure 1 As shown.

[0032] Step 2: Broadband ultrasonic surface wave detection experiment for crack defects on the surface of metallic materials.

[0033] Build a broadband ultrasonic surface wave detection experimental system, such as Figure 2 As shown. The system includes a metal material sample 1 containing crack defects, a surface crack defect 2, a broadband ultrasonic surface wave excitation sensor 3, a broadband ultrasonic surface wave receiving sensor 4, an excitation impedance matching module 5, a high-power pulse excitation receiving device 6, a preamplifier 7, a receiving impedance matching module 8, and a digital oscilloscope 9.

[0034] The experiment employed a single-excitation, single-receiver mode. A broadband surface wave sensor 3 was positioned at one end of the crack defect 2 as the excitation sensor, and a broadband surface wave sensor 4 was positioned at the other end as the receiving sensor. One end of the excitation-end impedance matching module 5 was connected to the excitation sensor 3. A high-power pulse excitation receiving device 6 was connected to the other end of the excitation-end impedance matching module 5 and was used to excite a broadband signal. The high-power pulse excitation receiving device 6 was connected to one end of the preamplifier 7, and the receiving-end impedance matching module 8 was connected to the other end of the preamplifier 7. The other end of the receiving-end impedance matching module 8 was connected to the broadband ultrasonic surface wave receiving sensor 4. The high-power pulse excitation receiving device 6 was connected to a digital oscilloscope 9. The digital oscilloscope 9 was used to observe and save the excitation and received signals.

[0035] Broadband ultrasonic surface wave testing was performed on a crack-free sample to obtain the corresponding broadband surface wave transmission signal and time-frequency analysis diagram, as shown below. Figure 3 As shown. Broadband ultrasonic surface wave detection experiments were conducted on different crack defects to obtain the corresponding broadband surface wave transmission signals, such as... Figure 4 As shown, as the surface crack defects change, the amplitude and time-of-flight of the surface wave transmission signal, and other ultrasonic parameters, change accordingly. The surface wave transmission signal contains information related to the surface crack defects. Figure 5 for Figure 4The time-frequency analysis diagram of the transmitted surface wave signal shows that as the crack length increases, the high-frequency components of the broadband signal have shorter wavelengths. When the crack length is greater than the wavelength depth of the high-frequency surface wave, the high-frequency surface wave will bypass the crack and propagate to the receiving sensor. Therefore, the high-frequency energy exhibits a time delay in the time-frequency domain. Conversely, the low-frequency components of the broadband signal have longer wavelengths. When the crack length is greater than the wavelength depth of the high-frequency surface wave but less than the wavelength depth of the low-frequency surface wave, the low-frequency surface wave can still propagate directly to the receiving sensor. Therefore, the low-frequency energy does not change significantly in the time-frequency domain. However, when the crack length is greater than the wavelength depth of the low-frequency surface wave, the low-frequency surface wave also needs to bypass the crack to propagate to the receiving sensor. Therefore, in the time-frequency domain, the broadband surface wave energy collectively exhibits a time delay. Based on the interaction patterns between ultrasonic surface waves of different frequency components and cracks of different lengths in the time-frequency analysis diagram, ultrasonic characteristic parameters of different frequency components are extracted for quantitative evaluation of surface crack defects.

[0036] Step 3: Broadband ultrasonic surface wave quantitative evaluation of surface crack defects in metallic materials.

[0037] A schematic diagram of the quantitative evaluation model of characteristic parameters is shown below. Figure 6 As shown, the neural network in the quantitative evaluation model can be divided into an input layer, a hidden layer, and an output layer, with each layer connected to the next. Input information is obtained through the input layer, and then features are extracted using the hidden layer, which contains its own biases and weights. The final output layer connects to the hidden layer and outputs the model results. Non-wideband ultrasonic feature parameters and wideband ultrasonic feature parameters are used to quantitatively characterize cracks. Using ultrasonic feature parameters as input parameters and surface crack defect information as output parameters, a mapping model between ultrasonic feature parameters and surface crack defect information of metallic materials is constructed.

[0038] Quantitative evaluation results of single-frequency and broadband ultrasound parameters are as follows: Figure 7 As shown, single-frequency ultrasonic characteristic parameters are used for quantitative crack evaluation. When the crack length is greater than the depth of the low-frequency surface wave wavelength, the evaluation capability of single-frequency ultrasonic characteristic parameters is acceptable. However, when the crack length is between the depth of the high-frequency wavelength and the depth of the low-frequency wavelength, the crack length prediction error is large, and the evaluation capability of single-frequency ultrasonic characteristic parameters is limited. When broadband ultrasonic characteristic parameters are used for quantitative crack evaluation, the crack length prediction error can be significantly reduced, and broadband ultrasonic characteristic parameters can improve the ability to quantitatively evaluate surface crack defects in metallic materials.

[0039] This invention presents a broadband ultrasonic surface wave quantitative evaluation method for surface crack defects in metallic materials. Addressing the quantitative evaluation of surface crack defects in metallic materials, it leverages the sensitivity of ultrasonic surface waves propagating near the material surface to surface crack defects. It also considers the rich frequency component information of broadband surface wave signals, noting that different frequency components exhibit varying wavelengths and depths, leading to different interactions with crack defects. A broadband ultrasonic surface wave excitation sensor is used to excite broadband ultrasonic surface waves to detect surface crack defects in metallic materials. A broadband ultrasonic surface wave receiving sensor receives the transmitted ultrasonic surface wave signal after interaction with the surface crack defect. Time-frequency analysis is used to obtain the time-frequency analysis diagram of the transmitted surface wave signal, analyzing the interaction patterns between surface waves of different frequency components and crack defects. Ultrasonic characteristic parameters at different frequency components are extracted, and a mapping model between the input ultrasonic characteristic parameters and the output information of surface crack defects in metallic materials is constructed. This allows for the broadband ultrasonic surface wave quantitative evaluation of surface crack defects in metallic materials. The proposed method addresses the limitation of single-frequency ultrasonic surface waves in evaluating surface crack defects. Based on the interaction between ultrasonic surface waves of different frequency components and surface crack defects, it extracts ultrasonic characteristic parameters at different frequency components, thereby improving the quantitative evaluation capability of surface crack defects in metallic materials. This method has significant application value in the fields of nondestructive testing and structural health monitoring.

Claims

1. A broadband ultrasonic surface wave quantitative evaluation method for surface crack defects in metallic materials, characterized in that: A broadband surface wave sensor detects and acquires broadband ultrasonic surface wave signals; the interaction between broadband ultrasonic surface waves of different frequency components and crack defects of different lengths is analyzed; ultrasonic characteristic parameters of different frequency components of broadband ultrasonic surface waves are extracted; a mapping relationship between ultrasonic characteristic parameters and surface crack defect information of metallic materials is established to achieve quantitative evaluation of surface crack defects of metallic materials using broadband ultrasonic surface waves. The broadband ultrasonic surface wave sensor generates a broadband ultrasonic surface wave signal. The broadband ultrasonic surface wave signal is different from the single-frequency signal in that it is a linear frequency modulated signal. The frequency range of the broadband signal is from 100 kHz to 10 MHz. When detecting surface cracks and defects in metallic materials, the signal is selected within this frequency range according to the specific object to be detected and the detection accuracy. The variation trends of arrival time, amplitude and phase of ultrasonic surface waves with different frequency components under surface crack defects of different lengths were obtained, and the interaction law between ultrasonic surface waves with different frequency components and surface crack defects was analyzed based on time-frequency analysis method. Ultrasonic characteristic parameters of different frequency components were obtained from the broadband ultrasonic surface wave signal after interaction with surface crack defects. The ultrasonic characteristic parameters include ultrasonic arrival time, amplitude and phase. Establish the mapping relationship between ultrasonic characteristic parameters of different frequency components in broadband ultrasonic surface waves and crack defects on metal surfaces; Based on the mapping relationship between broadband ultrasonic characteristic parameters and metal surface crack defect information, a multivariate linear regression analysis was conducted with broadband ultrasonic characteristic parameters as multivariate independent variables and the length of metal surface crack defects as dependent variable. The regression coefficients and sum of squares of deviations were calculated to achieve a quantitative evaluation of metal surface crack defects using broadband ultrasonic surface waves.

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