An ultrasonic array imaging method, system, device, and medium for water-immersed curved surface members

Abstract

The application relates to the technical field of detection methods, in particular to an ultrasonic array imaging method, system, device and medium for a water-immersed curved component, which comprises the following steps: acquiring initial full-matrix data of the curved component under a water-immersed condition, extracting and fitting a surface contour from the initial full-matrix data for preliminary imaging, and constructing an initial curved background model; performing spatial discretization processing on the initial curved background model to obtain a discretized model; and performing pretreatment on the full-matrix data to obtain time-reversed full-matrix data; performing forward time-domain extrapolation processing based on the discretized model to obtain a source wave field, and performing reverse time-domain extrapolation processing according to the time-reversed full-matrix data to obtain a received wave field; and applying a cross-correlation imaging condition to the source wave field and the received wave field to obtain a final imaging result, so that the curved component is stably imaged and the imaging accuracy is improved.

Description

Technical Field

[0001] This application relates to the technical field of detection methods, and in particular to an ultrasonic array imaging method, system, device and medium for water-immersed curved surface components. Background Technology

[0002] Curved components are widely used in aerospace, energy, and chemical industries. However, they are prone to developing complex cracks under harsh operating conditions, threatening equipment safety. To achieve reliable detection and accurate characterization, ultrasonic array imaging technology is widely adopted due to its high resolution and superior imaging capabilities. Among these methods, reverse time migration (RTM) can fully utilize the entire matrix data to reconstruct the complex wave field scattering at the defect location. This overcomes, to some extent, the imaging limitations of traditional methods in complex structures, multi-path propagation, and large-angle defects, making it one of the key technologies for achieving high-precision defect reconstruction.

[0003] Current RTM technology focuses on contact testing, where the ultrasonic probe must be directly coupled to the component surface. This method requires a high degree of surface flatness and struggles to achieve stable and uniform acoustic coupling on components with varying curvature and complex shapes. This not only makes operation inconvenient but also leads to signal energy loss and poor consistency, affecting the reliability and accuracy of imaging. While frequency-domain reverse time migration (RTM) methods, developed to circumvent contact coupling problems, have been initially applied to curved components, their imaging quality depends on manually set frequency bandwidth. The lack of standardized subjective parameter selection increases instability, causing imaging results to vary depending on the experience of the processing personnel. This makes it difficult to meet the stringent requirements of objectivity and repeatability in industrial testing, and these problems remain to be solved. Summary of the Invention

[0004] To achieve stable imaging of curved components and improve imaging accuracy, this application provides an ultrasonic array imaging method, system, device, and medium for water-immersed curved components, employing the following technical solution: In a first aspect, this application provides an ultrasonic array imaging method for water-immersed curved surface components, comprising: The initial full matrix data of the curved surface component under water immersion conditions is obtained. The surface contour is extracted and fitted from the initial full matrix data for preliminary imaging to construct the initial curved surface background model. The initial curved surface background model is spatially discretized to obtain a discretized model; and the full matrix data is preprocessed to obtain time-inverse full matrix data. Based on the discretized model, forward time-domain extrapolation is performed to obtain the source wave field, and inverse time-domain extrapolation is performed based on the time-inverse full matrix data to obtain the received wave field. By applying cross-correlation imaging conditions to the source and received wave fields, the final imaging result is obtained.

[0005] Preferably, the specific steps for extracting and fitting the surface contour from the initial full matrix data for preliminary imaging to construct the initial curved surface background model are as follows: Preliminary imaging of the full matrix data yields the amplitude matrix; The first sample point is obtained by extracting the pixels of the amplitude matrix based on the current threshold; The initial surface background model is obtained by fitting the contour of the water-solid coupling surface component based on the first sample point.

[0006] Preferably, the specific steps for preprocessing the full matrix data to obtain the inverse full matrix data are as follows: The arrival time of the direct wave is calculated based on the propagation speed of ultrasonic waves in water and the length of the ultrasonic probe. The signal of the full matrix data before the arrival time of the direct wave is set to zero to obtain the time-inverse full matrix data.

[0007] Preferred options also include: The pixels of the amplitude matrix are extracted based on the initial threshold to obtain the second sample points. If the number of points in the second sample points is lower than the preset value, the initial threshold is reduced to obtain the current threshold. If the number of discrete noise points in the second sample points is higher than the preset value, the initial threshold is increased to obtain the current threshold.

[0008] Preferably, the initial curved surface background model includes water layer density parameters, water layer velocity parameters, component density parameters, and component velocity parameters.

[0009] Preferably, the specific steps for obtaining the source wavefield by performing forward time-domain extrapolation based on the discretized model and inverse time-domain extrapolation based on the time-inverse full matrix data are as follows: Based on the discretized model, the original excitation signal is applied to the transmitting array element according to each positive time step to obtain the source wave field; Based on each inverse time step, time-inverse full matrix data is applied to the receiving array elements to obtain the received wave field.

[0010] Preferably, the cross-correlation imaging conditions are: ; in, For the imaging results corresponding to all time steps T; t represents the total signal acquisition time; t represents the time step. For the source wave field at the current time step, This represents the received wave field at the current time step.

[0011] Secondly, this application provides an ultrasonic array imaging system for water-immersed curved surface components, comprising: The model building module is used to acquire the initial full matrix data of the curved surface component under water immersion conditions, extract and fit the surface contour from the initial full matrix data for preliminary imaging, and construct the initial curved surface background model. The preprocessing module is used to spatially discretize the initial curved surface background model to obtain a discretized model; and to preprocess the full matrix data to obtain time-inverse full matrix data. The wave field update module is used to perform forward time-domain extrapolation based on the discretized model to obtain the source wave field, and to perform inverse time-domain extrapolation based on the time-inverse full matrix data to obtain the received wave field. The imaging module is used to apply cross-correlation imaging conditions to the source wavefield and the received wavefield to obtain the final imaging result.

[0012] Thirdly, this application provides an ultrasonic array imaging device for water-immersed curved surface components, including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the ultrasonic array imaging method for water-immersed curved surface components as described above.

[0013] Fourthly, this application provides a computer-readable storage medium storing a computer program, wherein the computer program is configured to execute the ultrasonic array imaging method for water-immersed curved surface components as described above when running.

[0014] In summary, compared with the prior art, the beneficial effects of the technical solution provided in this application include at least the following: This application acquires initial full matrix data of a curved surface component coupled with a water medium and a solid medium under water immersion conditions, performs preliminary imaging on the initial full matrix data, extracts and fits the initial curved surface background model of the surface contour component, processes the model and full matrix data to obtain a discretized model and time-inverse full matrix data, performs forward time-domain extrapolation and inverse time-domain extrapolation based on the discretized model and time-inverse full matrix data, and performs imaging on the obtained source wave field and received wave field to obtain the final imaging result. This effectively overcomes the limitations of contact coupling, reduces subjective parameter interference, enables stable imaging of curved surface components, and improves imaging accuracy. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of an ultrasonic array imaging method for a water-immersed curved surface component as described in an embodiment of this application.

[0016] Figure 2 This is a schematic diagram illustrating the principle of surface contour fitting as described in the embodiments of this application.

[0017] Figure 3 This is a schematic diagram of the signal after removing the direct wavefront and the signal after removing the direct wavefront, as described in the embodiments of this application.

[0018] Figure 4 This is a partial schematic diagram of the medium pressure field and the interlaced grid described in the embodiments of this application.

[0019] Figure 5 This is a schematic diagram of experimental data acquisition as described in the embodiments of this application.

[0020] Figure 6 This is a schematic diagram of a module of an ultrasonic array imaging system for a water-immersed curved surface component as described in an embodiment of this application.

[0021] Explanation of reference numerals in the attached figures: 1. Model building module; 2. Preprocessing module; 3. Wavefield update module; 4. Imaging module. Detailed Implementation

[0022] The following combination Figures 1-6 The present application will be described in further detail below. The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0023] Reference Figure 1 The ultrasonic array imaging method for water-immersed curved surface components involved in this application specifically includes: Step S1: Obtain the initial full matrix data of the curved surface component under water immersion conditions, extract and fit the surface contour from the initial full matrix data for preliminary imaging, and construct the initial curved surface background model. Step S2: Spatial discretization is performed on the initial curved background model to obtain a discretized model; and the initial full matrix data is preprocessed to obtain time-inverse full matrix data. Step S3: Based on the discretized model, perform forward time-domain extrapolation to obtain the source wave field, and perform inverse time-domain extrapolation based on the time-inverse full matrix data to obtain the received wave field; Step S4: Apply cross-correlation imaging conditions to the source wave field and the received wave field to obtain the final imaging result.

[0024] Specifically, this embodiment acquires initial full-matrix data of a curved component coupled with a water-solid medium under water immersion conditions. Preliminary imaging is performed on the initial full-matrix data, and an initial curved surface background model of the component is extracted and fitted. By constructing a curved surface background model including both water and solid layers, an accurate description of the ultrasonic wave propagation process in the water-solid coupled medium is achieved, significantly improving the imaging accuracy of internal defects in the curved component. The model and full-matrix data are processed to obtain a discretized model and time-inverse full-matrix data. Based on the discretized model and time-inverse full-matrix data, forward and backward time-domain extrapolation are performed to obtain the source and received wave fields. The source and received wave fields are reconstructed step-by-step based on the model, enabling the reverse-time migration imaging process to accurately reflect the propagation path of ultrasonic waves entering the solid interior through the curved interface under water immersion conditions, thereby effectively reducing imaging distortion caused by the curved interface. Imaging using the source and received wave fields yields the final imaging result, effectively overcoming contact coupling limitations, reducing subjective parameter interference, ensuring stable imaging of the curved component, and improving imaging accuracy.

[0025] The time-domain reverse time offset processing used in this application embodiment can naturally cover all effective frequency components in a single time-domain extrapolation process, without the need for frequency selection and frequency stepping design, making the imaging process more stable and controllable, and the implementation process is simple.

[0026] As one implementation method, the specific steps for extracting and fitting the surface contour from the initial full matrix data for preliminary imaging to construct the initial curved surface background model are as follows: Preliminary imaging is performed on the initial full matrix data to obtain the amplitude matrix; The first sample point is obtained by extracting the pixels of the amplitude matrix based on the current threshold; The initial surface background model is obtained by fitting the contour of the water-solid coupling surface component based on the first sample point.

[0027] Specifically, in this embodiment of the application, under water immersion detection conditions, the full matrix data of the curved surface component is acquired. Assuming the imaging area is a single water medium, a full-focusing method is used to initially image the full matrix data, obtaining the amplitude matrix of the imaging area. Based on the characteristics of the amplitude matrix, a current threshold for contour extraction is determined, and the amplitude matrix is ​​processed based on the current threshold to extract pixels that meet the conditions, serving as sample points for contour extraction. Mathematical fitting is performed on the sample points to obtain a mathematical expression describing the contour of the curved surface component under water-solid coupling.

[0028] The surface fitting in this embodiment adopts the full focusing method. The full focusing method is only used for extracting the surface contour under water immersion conditions. The purpose is to construct an accurate water-solid interface geometric model for reverse time-shift imaging.

[0029] Reference Figure 2The surface fitting process is as follows Figure 2 The middle circle represents the imaging point, such as Figure 2 In the image, point A is imaged using its amplitude matrix, where solid circles represent points with higher amplitudes, such as... Figure 2 In section B, when ultrasonic waves pass through an interface with discontinuous acoustic impedance, complex reflection and refraction phenomena occur at the interface. Therefore, when calculating the amplitude of the area to be measured, the amplitude at the contour of the curved component is usually higher, making the contour features clearly presented in the TFM image.

[0030] To address the issues of ultrasonic waves being reflected and refracted at the water-solid interface during water immersion testing, this application employs a full-focusing method to extract and fit the surface contour of curved components, constructing a curved background model that includes both a water layer and a solid layer.

[0031] As one implementation method, it also includes: The pixels of the amplitude matrix are extracted based on the initial threshold to obtain the second sample points. If the number of points in the second sample points is lower than the preset value, the initial threshold is reduced to obtain the current threshold. If the number of discrete noise points in the second sample points is higher than the preset value, the initial threshold is increased to obtain the current threshold.

[0032] Specifically, in this embodiment, since only the sound velocity of the first layer of medium is considered during calculation, only the echo information corresponding to the curved surface contour is accurate. After obtaining the TFM image, it is observed that the curved surface contour corresponds to the darker colored area in the image. To extract the contour information from it, the amplitude matrix needs to be thresholded. By setting an appropriate threshold... The half-wave method is typically used for initial threshold setting, i.e., threshold. Set the threshold to 0.5 as the initial threshold; perform preliminary contour extraction based on the initial threshold; if the extracted second sample points are discontinuous or the number of points is small, then decrease the initial threshold; if the extracted second sample points contain a large number of discrete noise points, then increase the initial threshold.

[0033] As one implementation method, the initial curved surface background model includes water layer density parameters, water layer velocity parameters, component density parameters, and component velocity parameters.

[0034] Specifically, in this embodiment, after the current threshold is set, pixels with amplitudes higher than this threshold are connected to obtain a complete contour curve, and the coordinates of these points are extracted as first sample points. Based on the first sample points, an nth-order polynomial is used to fit the surface contour to obtain: ; Where 'a' represents the polynomial coefficients, and by fitting the coordinate points, a mathematical expression for the interface contour can be obtained, thus establishing an accurate curved background model for RTM imaging. The curved background model includes the density parameters of the water layer and curved components. speed parameters .

[0035] As one implementation method, the specific steps for preprocessing the initial full matrix data to obtain the inverse full matrix data are as follows: The arrival time of the direct wave is calculated based on the propagation speed of ultrasonic waves in water and the length of the ultrasonic probe. The signal of the initial full matrix data before the arrival time of the direct wave is set to zero to obtain the time-inverse full matrix data.

[0036] Specifically, in this embodiment of the application, the arrival time of the direct wave is calculated based on the propagation speed of ultrasonic waves in the water medium and the length of the ultrasonic probe. The signal before the arrival time of the direct wave is set to zero to suppress the interference of the direct wave on the imaging results, and the processed signal is used as the excitation signal for reverse time extrapolation.

[0037] Reference Figure 3 In this embodiment of the application, the preprocessing calculates the arrival time of the direct wave based on the ultrasonic wave propagation speed in the water medium and the length of the ultrasonic probe. The signal before the arrival time of the direct wave is set to zero. The signals before and after the direct wave are removed as follows: Figure 3 As shown. Among them, Figure 3 (a) is the original signal when the 32nd element is excited. Figure 3 (b) is the signal after removing the direct wave from the 32nd array element.

[0038] The water immersion detection method in this application exhibits significant efficiency advantages when dealing with complex curved surfaces due to its non-contact coupling mechanism. The Time-Domain Reverse Time Migration (TD-RTM) algorithm is extended to ultrasonic testing of curved components under water immersion conditions. By coupling the water medium with the solid medium, a curved surface background model is constructed, enabling high-precision imaging of complex cracks inside the curved component and providing an accurate sound field propagation model for subsequent wavefield extrapolation.

[0039] As one implementation method, based on the discretized model, forward time-domain extrapolation is performed to obtain the source wave field, and inverse time-domain extrapolation is performed based on the time-inverse full matrix data to obtain the received wave field. The specific steps are as follows: Based on the discretized model, the original excitation signal is applied to the transmitting array element according to each positive time step to obtain the source wave field; Based on each inverse time step, time-inverse full matrix data is applied to the receiving array elements to obtain the received wave field.

[0040] Specifically, embodiments of this application utilize the theoretical formulas for calculating the source wave field and the received wave field using staggered grid finite difference.

[0041] In this embodiment, for curved components, the water immersion method is used for detection. Only longitudinal waves propagate in water, while mode conversion only occurs in the solid medium. Furthermore, the main signal component in the solid is still longitudinal waves; therefore, imaging utilizes only longitudinal waves. In an isotropic medium where water and solid are coupled, the first-order acoustic velocity-stress equation in the time domain can be used: ; in, It is a medium pressure field. It is the lateral velocity component. It is the longitudinal velocity component. It is the density of the medium. It is time. It is the velocity of the longitudinal wave in the medium. , These are coordinates in a two-dimensional spatial domain, representing the horizontal and vertical directions, respectively.

[0042] During the imaging process, only a limited area is calculated. Ultrasonic waves are reflected at the boundaries, causing the propagation process to deviate from reality and affecting the imaging results. To ensure the ultrasonic wave propagation process conforms to reality, appropriate absorbing boundary conditions need to be introduced into the imaging process to absorb and attenuate the ultrasonic waves, thereby obtaining better imaging effects and methods. After introducing perfectly matched layer PML boundary conditions at the model boundaries, the first-order acoustic velocity-stress equation in the time domain is: ; in, , These are the medium pressure fields. The horizontal and vertical components after decomposition , These are the attenuation factors in the x and z directions, respectively.

[0043] in: ; in, It is the thickness of the absorption layer. It is the maximum speed of sound in the medium. , These represent the number of grid cells between the horizontal and vertical computation layers and the normal computation region, respectively. It is the number of grids in the absorption layer. It is the reflection coefficient, which is usually taken as 10⁻⁶.

[0044] Reference Figure 4 In engineering practice, the discretized wave field values ​​are calculated using staggered mesh finite difference. The discretized medium pressure field is as follows: Figure 4As shown in (a), it includes both an aqueous medium and a solid medium. The entire curved background model region is discretized into... The staggered-grid finite difference method performs better in the time domain. Staggered grids are simpler and more direct to implement, and can better handle phenomena such as wave reflection and refraction. The staggered-grid finite difference method is used to solve the pressure field of a medium. Longitudinal velocity wave field and transverse velocity wave field Interlaced grid structure, such as Figure 4 As shown in (b). Establish in space Two coordinate systems, with different variables placed on different grids.

[0045] The medium pressure field of this application embodiment Discretized at the full grid, velocity wave field and It is discretized at the half-grid. The discretized wave equation is: ; ; ; ; ; Where C represents the difference coefficients for spatial difference precision. The discretized wave equation is solved based on the above equations to model the wave field. In the TD-RTM surface component, spatial discretization uses tenth-order precision, and time discretization uses second-order precision.

[0046] As one implementation method, the cross-correlation imaging conditions are: ; in, For the imaging results corresponding to all time steps T; t represents the total signal acquisition time; t represents the time step. For the source wave field at the current time step, This represents the received wave field at the current time step.

[0047] Specifically, in this embodiment of the application, the imaging results corresponding to all array elements are superimposed and calculated, as follows: ; In the formula, The table shows the imaging results of internal defects in curved surface components in the time domain.

[0048] This application employs a full-focusing method to extract and fit the surface contour of curved components, constructing a curved background model that includes both water and solid layers, providing an accurate sound field propagation model for subsequent wavefield extrapolation. Based on this curved background model, the source and received wavefields are reconstructed step-by-step using time-domain acoustic wave equations to simulate the propagation process of ultrasound in a water-solid coupling medium. This enables the effective utilization of multipath propagation and multiple echo information, thereby accurately characterizing complex cracks within the curved components. Compared to traditional time-based imaging methods, this application introduces multiple echo information during the imaging process, significantly improving imaging accuracy. Compared to frequency-domain reverse time migration methods, time-domain reverse time migration methods do not require frequency selection or frequency stepping design, naturally covering all effective frequency components in a single time-domain calculation. The imaging process is more stable, controllable, and easier to implement.

[0049] This application verifies the effectiveness of the method of the present invention for imaging defects in curved components through experiments: Reference Figure 5 , Figure 5 As shown in (a), this is a schematic diagram of FMC data acquisition for internal hole defects in a part. Water immersion testing was used to measure Y-shaped and Z-shaped defects in the aluminum component. For each defect, the ultrasonic transducer was positioned directly above the defect via motion control and horizontally adjusted. The water depth distance between the ultrasonic transducer and the sample was 13 mm. Two types of test blocks were prepared, named Y-shaped and Z-shaped from left to right, as shown in (d) and (e). (d) is a schematic diagram of a Y-shaped defect, and (e) is a schematic diagram of a Z-shaped defect. Each test block contained one defect. A 64-element ultrasonic array transducer (Imasonic) with a center frequency of 5 MHz and an element spacing of 0.5 mm was used in the experiment, along with a three-degree-of-freedom motorized robotic arm and a Vantage 64 ultrasonic system (Verasonics), to achieve FMC data acquisition. The sampling frequency was 62.5 MHz, and a total of 12,800 sampling points were collected. A two-layer model was formed in the measurement area. The sound velocity of water was 1496 m / s and the density was 1000 kg / m3; the sound velocity of aluminum was 6320 m / s and the density was 2700 kg / m3.

[0050] Two imaging methods were used to process the FMC dataset, including TFM-based imaging and the TD-RTM imaging method described in this application. TFM uses ray tracing to calculate the time delay of each image pixel, thereby determining the amplitude of each imaging point. For TD-RTM, the measurement region is discretized in the x and z directions with a grid size of 0.05 mm, resulting in 15-20 grid points for each shortest wavelength in the solid. The time step is... To meet the dispersion standard.

[0051] Before imaging, the TFM method is used to fit the curved surface components. The fitting results are shown in Figures (b) and (c). (b) shows the comparison between the surface fitting curve of the Y-shaped defect and the actual surface contour, and (c) shows the comparison between the surface fitting curve of the Z-shaped defect and the actual surface contour. The solid line of the realistic outline represents the actual curve contour, and the dashed line of the fit outline represents the fitted surface contour. In this way, a curved background model is established.

[0052] The imaging results of the Y-shaped and Z-shaped crack defect specimens using the two imaging methods are as follows: Figure 5 (f)-(g) and Figure 5 (h) As shown in (i), (f) is the imaging result of the Y-shaped defect inside the curved component using the TFM imaging method, (g) is the imaging result of the Z-shaped defect inside the curved component using the TFM imaging method, (h) is the imaging result of the Y-shaped defect inside the curved component using the RTM imaging method, and (i) is the imaging result of the Z-shaped defect inside the curved component using the RTM imaging method. The dashed lines represent the actual defect contours.

[0053] For Experiment 1, i.e., the Y-shaped crack, the Y-shaped crack shape in the TD-RTM imaging results is as follows: Figure 5 In the middle (h), compared to TFM, such as Figure 5 The Y-shaped crack in the (f) imaging result is much more complete. TD-RTM can fully present the Y-shaped outline, especially the longitudinal branch crack. In contrast, TFM can only present the upper end of the longitudinal branch crack, and the other two branch cracks are not fully displayed.

[0054] To further compare the imaging effects of the two methods, amplitude analysis was performed on the longitudinal branch crack region. Extraction Figure 5 The amplitude data in the yellow dashed lines marked in (f) and (h) are normalized based on the maximum amplitude value of the two methods in the marked areas of each figure. Figure 5 (j) shows the normalized amplitude curve of the Y-shaped defect at the marked location. Imaging results indicate that the horizontal location of the longitudinal branch crack should be near 0 mm. If the crack can be imaged, the normalized amplitude at this location should show a peak. Figure 5As shown in (j), in the amplitude curve of the TFM method (dashed line), the peak values ​​all appear at the lower bounded area of ​​the curve, while the amplitude at the actual crack location, near 0 mm, is essentially zero, indicating that TFM is insufficient in characterizing longitudinal branch cracks. In contrast, the amplitude curve of the TD-RTM method (solid line) shows the highest peak value near 0 mm, i.e., at the peak bounded area, proving that TD-RTM can effectively characterize longitudinal branch cracks in defects, and its effect is better than TFM. Due to the lack of left and right absorption boundaries during imaging, interference from factors such as clutter is introduced, resulting in areas with higher amplitudes around the peak bounded area in the RTM amplitude curve.

[0055] For Experiment 2, i.e., the Z-shaped defect, both imaging methods could clearly display the defect shape. However, the TFM-based imaging method showed a significant difference in shape between the left and right tilted cracks in the Z-shaped defect, and there were many artifacts above and below the defect in the image. In contrast, the TD-RTM imaging method showed that the shapes of the left and right tilted cracks in the Z-shaped defect were more similar, but the right tilted crack had a relatively lower amplitude due to its greater distance from the array element.

[0056] To further compare imaging results, extract Figure 5 The amplitude data of the regions marked by the yellow dashed lines in (g) and (i) are normalized based on the maximum amplitude value in each region. Figure 5 (k) shows the normalized amplitude curves of the Z-shaped defect at the marked location. The amplitude curves of both methods peak at the actual defect location, and the main lobe widths are essentially the same. However, the TFM method's amplitude curve has more side lobes, i.e., the blue area in the figure, corresponding to artifacts in the image. The TD-RTM method, on the other hand, shows better side lobe suppression in its amplitude curve, demonstrating stronger artifact suppression capabilities.

[0057] Therefore, compared with the TFM method, this application has significant advantages in characterizing complex crack morphology, especially for longitudinal branch cracks.

[0058] Reference Figure 6 This application provides an ultrasonic array imaging system for water-immersed curved surface components, the system comprising: Model building module 1 is used to acquire the initial full matrix data of the curved surface component under water immersion conditions, extract and fit the surface contour from the initial full matrix data for preliminary imaging, and construct the initial curved surface background model. Preprocessing module 2 is used to spatially discretize the initial curved surface background model to obtain a discretized model; and to preprocess the full matrix data to obtain time-inverse full matrix data. Wavefield update module 3 is used to perform forward time-domain extrapolation based on the discretized model to obtain the source wavefield, and to perform inverse time-domain extrapolation based on the time-inverse full matrix data to obtain the received wavefield. Imaging module 4 is used to apply cross-correlation imaging conditions to the source wave field and the received wave field to obtain the final imaging result.

[0059] This application provides an ultrasonic array imaging device for water-immersed curved surface components, including a memory and a processor. The memory stores a computer program, and the processor is configured to run the computer program to perform the ultrasonic array imaging method for water-immersed curved surface components as described above.

[0060] This application provides a computer-readable storage medium storing a computer program, wherein the computer program is configured to execute the ultrasonic array imaging method for water-immersed curved surface components as described above when running.

[0061] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the device and product described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0062] In the several embodiments provided in this application, it should be understood that the disclosed methods, systems, apparatus and program products can be implemented in other ways.

[0063] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0064] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An ultrasonic array imaging method for water-immersed curved surface components, characterized in that, include: The initial full matrix data of the curved surface component under water immersion conditions is obtained. The surface contour is extracted and fitted from the initial full matrix data for preliminary imaging to construct the initial curved surface background model. The initial curved surface background model is spatially discretized to obtain a discretized model; and the initial full matrix data is preprocessed to obtain time-inverse full matrix data. Based on the discretized model, forward time-domain extrapolation is performed to obtain the source wave field, and inverse time-domain extrapolation is performed based on the time-inverse full matrix data to obtain the received wave field. By applying cross-correlation imaging conditions to the source and received wave fields, the final imaging result is obtained.

2. The ultrasonic array imaging method for water-immersed curved surface components according to claim 1, characterized in that, The specific steps for extracting the initial full matrix data for preliminary imaging and fitting the surface contour to construct the initial curved surface background model are as follows: Preliminary imaging is performed on the initial full matrix data to obtain the amplitude matrix; The first sample point is obtained by extracting the pixels of the amplitude matrix based on the current threshold; The initial surface background model is obtained by fitting the contour of the water-solid coupling surface component based on the first sample point.

3. The ultrasonic array imaging method for water-immersed curved surface components according to claim 1, characterized in that, The specific steps for preprocessing the initial full matrix data to obtain the inverse full matrix data are as follows: The arrival time of the direct wave is calculated based on the propagation speed of ultrasonic waves in water and the length of the ultrasonic probe. The signal of the initial full matrix data before the arrival time of the direct wave is set to zero to obtain the time-inverse full matrix data.

4. The ultrasonic array imaging method for water-immersed curved surface components according to claim 2, characterized in that, Also includes: The pixels of the amplitude matrix are extracted based on the initial threshold to obtain the second sample points. If the number of points in the second sample points is lower than the preset value, the initial threshold is reduced to obtain the current threshold. If the number of discrete noise points in the second sample points is higher than the preset value, the initial threshold is increased to obtain the current threshold.

5. The ultrasonic array imaging method for water-immersed curved surface components according to claim 1, characterized in that, The initial curved surface background model includes water layer density parameters, water layer velocity parameters, component density parameters, and component velocity parameters.

6. The ultrasonic array imaging method for water-immersed curved surface components according to claim 1, characterized in that, The specific steps for obtaining the source wavefield by performing forward time-domain extrapolation based on the discretized model and inverse time-domain extrapolation based on the time-inverse full matrix data are as follows: Based on the discretized model, the original excitation signal is applied to the transmitting array element according to each positive time step to obtain the source wave field; Based on each inverse time step, time-inverse full matrix data is applied to the receiving array elements to obtain the received wave field.

7. The ultrasonic array imaging method for water-immersed curved surface components according to claim 1, characterized in that, The cross-correlation imaging conditions are: ； in, For the imaging results corresponding to all time steps T; t represents the total signal acquisition time; t represents the time step. For the source wave field at the current time step, This represents the received wave field at the current time step.

8. An ultrasonic array imaging system for water-immersed curved surface components, characterized in that, include: The model building module is used to acquire the initial full matrix data of the curved surface component under water immersion conditions, extract and fit the surface contour from the initial full matrix data for preliminary imaging, and construct the initial curved surface background model. The preprocessing module is used to spatially discretize the initial curved surface background model to obtain a discretized model; and to preprocess the full matrix data to obtain time-inverse full matrix data. The wave field update module is used to perform forward time-domain extrapolation based on the discretized model to obtain the source wave field, and to perform inverse time-domain extrapolation based on the time-inverse full matrix data to obtain the received wave field. The imaging module is used to apply cross-correlation imaging conditions to the source wavefield and the received wavefield to obtain the final imaging result.

9. An ultrasonic array imaging device for water-immersed curved surface components, characterized in that, It includes a memory and a processor, the memory storing a computer program and the processor being configured to run the computer program to perform the ultrasonic array imaging method for a water-immersed curved surface member as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, wherein the computer program is configured to execute, when run, the ultrasonic array imaging method for a water-immersed curved surface component as described in any one of claims 1-7.

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