CN-122017033-A - Ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data combined calibration

CN122017033ACN 122017033 ACN122017033 ACN 122017033ACN-122017033-A

Abstract

The invention discloses an ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data joint calibration, which relates to the technical field of material detection and comprises the steps of S1, multi-source data space collaborative calibration; S2, echo signal feature extraction and joint optimization, S3, multi-view synthetic aperture three-dimensional imaging, S4, three-dimensional defect automatic identification and quantification. According to the ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data combined calibration, the reference reflection module is introduced to correct the probe pose and acoustic axis errors, the signal consistency is improved by combining empirical mode decomposition, depth gain compensation and cross-correlation phase alignment, and high-precision defect reconstruction and quantization are realized by adopting angle weighted full-focusing imaging and three-dimensional watershed segmentation, so that the problem of insufficient three-dimensional imaging precision caused by space reference deletion, echo inconsistency and unreasonable fusion weight of a multi-probe system can be effectively solved.

Inventors

ZHAO LIANG
WANG CHAO
ZHANG WEI
LIU DILONG

Assignees

常州天策电子科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260416

Claims (10)

1. An ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data joint calibration is characterized by comprising the following steps: S1, carrying out space collaborative calibration on multi-source data, namely arranging a plurality of ultrasonic probes on the surface of a workpiece to be tested, introducing a preset reference reflection module, acquiring space pose deviation and sound axis pointing error of each probe relative to a unified coordinate system through the module, and dynamically compensating the mounting position of the probe and the sound beam direction; S2, extracting echo signal characteristics and performing joint optimization; s201, performing empirical mode decomposition on the acquired multi-channel original echo signals, separating out high-frequency noise components and structure clutter components, and retaining eigenmode functions containing defect information; S202, constructing a depth-related gain compensation function according to attenuation rules of sound waves in the propagation process of the sound waves in the material, and carrying out point-by-point correction on echo amplitudes of layers with different depths; S203, calculating the maximum similarity offset between echo signals of adjacent probes by adopting a cross-correlation algorithm, and carrying out time axis translation on each channel signal according to the offset so as to align multi-view echoes in phase; s3, three-dimensional imaging of the multi-view synthetic aperture; S4, three-dimensional defect automatic identification and quantification.
2. The method according to claim 1, wherein S3 specifically further comprises the steps of: S301, dividing a region to be detected into three-dimensional voxel grids which are regularly arranged, wherein each voxel unit has unique space coordinates; S302, calculating the round trip sound path from each probe to each voxel unit based on the full focus imaging principle and combining the calibrated probe space parameters, and extracting the amplitude response at the moment from the corresponding channel echo; and S303, setting a weighting coefficient according to an included angle between the sound axis of the probe and the connecting line of the voxel center, and carrying out angle weighted superposition on voxel amplitudes from different view angles to generate a three-dimensional reconstruction image with high fidelity.
3. The method according to claim 1, wherein S4 specifically further comprises the steps of: s401, carrying out gradient enhancement treatment on the three-dimensional reconstruction image, and highlighting boundary difference between a defect area and a background; s402, carrying out region division on the enhanced image by applying a three-dimensional watershed segmentation algorithm, and extracting the connected regions corresponding to all local maxima as candidate defect bodies; S403, calculating the space volume, the length of the principal axis and the barycenter coordinates of each candidate defect body, and outputting a structural defect report.
4. The method of claim 1, wherein the reference reflection module in S1 is formed by a metal block with high acoustic impedance, a groove or step structure with a known geometric dimension is machined on the surface of the metal block and is fixed on the edge area of the workpiece to be measured, each ultrasonic probe is attached to the surface of the workpiece through a coupling agent and defines an initial installation position through a mechanical clamp, the probe array adopts an annular or matrix layout, the distance between adjacent probes is smaller than half a wavelength to meet the spatial sampling theorem, all the probes are connected to the same synchronous trigger controller, and excitation pulses with nanosecond precision are output by the controller to ensure that the echo acquisition starting time of each channel is consistent.
5. The method of claim 1, wherein the empirical mode decomposition in S201 employs an adaptive filtering strategy, the iteration termination condition is that a standard deviation of a residual signal is lower than a preset threshold, a first N-order eigenmode function is reserved after decomposition, N is determined by a signal energy concentration degree, the gain compensation function in S202 employs an exponential form, an attenuation coefficient of the gain compensation function is calibrated in advance according to a material type and a frequency response characteristic, the cross-correlation algorithm in S203 is implemented in a frequency domain, and a calculation process is accelerated through a fast fourier transform, so that a phase alignment precision reaches a sub-sampling point level.
6. The method according to claim 2, wherein the full focusing algorithm in S302 is based on an accurate sound velocity model, a sound velocity parameter is obtained through bottom echo flight time inversion, an amplitude response of each voxel is obtained by interpolation of a plurality of sampling points of the corresponding probe before and after a theoretical flight time, and the weighting coefficient in S303 adopts a cosine function form, namely, a cosine value with a weight equal to an included angle between a sound axis direction vector of the probe and a voxel center pointing vector, and the weight approaches zero when the included angle approaches 90 degrees, so that specular reflection interference caused by a large incident angle is suppressed.
7. The method of claim 1, wherein the step of monitoring the coupling state in real time is further comprised in the step of monitoring the coupling state in S1 by analyzing the time interval between the interface wave and the first bottom echo, and reversely pushing the actual thickness of the coupling layer between the probe wedge and the surface of the workpiece, and if the thickness deviates from the standard value by more than the tolerance range, marking the probe channel data as unreliable and rejecting or de-weighting the probe channel data in the subsequent imaging process.
8. The method of claim 1, wherein the step S201 further comprises a secondary denoising process, wherein wavelet threshold filtering is applied to residual signals obtained by empirical mode decomposition, wavelet basis functions matched with defect scales are selected, residual random noise is suppressed through a soft threshold strategy, and weak but continuous defect echo characteristics are reserved.
9. A method according to claim 3, wherein the gradient enhancement in S401 employs anisotropic diffusion filtering to smooth internal texture while maintaining defect edge sharpness, the three-dimensional watershed algorithm in S402 introduces morphological marker control to avoid over-segmentation, marker points are determined by local curvature extrema and gray peaks together, and the defect principal axis length in S403 is calculated by principal component analysis, and volume is obtained by voxel count times single voxel spatial resolution.
10. An ultrasonic three-dimensional nondestructive testing system based on multi-probe echo data joint calibration is applied to the ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data joint calibration, and is characterized by comprising a multi-probe ultrasonic sensing array, a high-precision synchronous excitation and acquisition unit, an embedded signal processing platform and a three-dimensional visualization terminal; The multi-probe ultrasonic sensing array consists of a plurality of broadband piezoelectric transducers, wherein each transducer is packaged in a wedge block with temperature compensation and is pressed on the surface of a workpiece through a spring loading mechanism to ensure coupling stability; The high-precision synchronous excitation and acquisition unit comprises a multi-channel high-voltage pulse generator and a high-speed analog-to-digital conversion module, all channels share the same crystal oscillator clock source, the jitter of the rising edge of an excitation pulse is less than ten picoseconds, the sampling rate of the analog-to-digital converter is not lower than million times per second, and the bit width is not lower than sixteen bits; the embedded signal processing platform is provided with a multi-core digital signal processor, the calibration, optimization and imaging algorithm is operated, the data flow adopts a double-buffer ping-pong mechanism, and the next frame of data is written into a standby buffer area during the current frame processing; The three-dimensional visual terminal receives the processing result through the gigabit Ethernet, supports drawing and slicing browsing, and can derive a defect three-dimensional model in the STL format for subsequent engineering analysis.

Description

Ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data combined calibration Technical Field The invention relates to the technical field of material detection, in particular to an ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data combined calibration. Background With the continuous improvement of the structural integrity requirements of advanced manufacturing and major equipment, the ultrasonic nondestructive detection technology plays an irreplaceable role in the key fields of aerospace, rail transit, energy equipment and the like, the core target of the ultrasonic nondestructive detection technology, namely the accurate positioning and quantitative evaluation of internal defects of materials, is directly related to the safe service and service life prediction of components, and the development of a high-precision and high-robustness three-dimensional ultrasonic imaging method for meeting the high-resolution detection requirements of complex geometric structures and micro defects has become an industrial key technical direction. The ultrasonic three-dimensional detection method based on the cooperation of multiple probes focuses on fusion of multi-view echo data, and achieves three-dimensional reconstruction of defect forms through spatial calibration and signal combined processing. The prior art still has a plurality of limitations in the aspect of multi-probe ultrasonic three-dimensional imaging, namely firstly, a multi-probe system lacks a uniform space reference, geometric mismatch is easily introduced by probe installation errors and acoustic axis deviation to influence voxel mapping accuracy, secondly, multi-channel echo signals are often interfered by factors such as noise, attenuation and phase inconsistency, if cooperative optimization is not carried out, imaging signal-to-noise ratio and consistency are reduced, finally, fusion weight setting of multi-view data by the traditional synthetic aperture imaging strategy is simplified, influence of an incident angle of an acoustic beam on reflection intensity is not fully considered, artifacts are possibly introduced or real defect characteristics are weakened, and the factors restrict application efficiency of the multi-probe ultrasonic system in a high-precision three-dimensional quantitative detection scene. Therefore, an ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data joint calibration is provided to solve the problems. Disclosure of Invention The invention mainly aims to provide an ultrasonic three-dimensional nondestructive testing method based on multi-probe echo data combined calibration so as to solve the problems in the background. In order to achieve the purpose, the technical scheme adopted by the invention is that the ultrasonic three-dimensional nondestructive testing method based on the multi-probe echo data combined calibration comprises the following steps: S1, carrying out space collaborative calibration on multi-source data, namely arranging a plurality of ultrasonic probes on the surface of a workpiece to be tested, introducing a preset reference reflection module, acquiring space pose deviation and sound axis pointing error of each probe relative to a unified coordinate system through the module, and dynamically compensating the mounting position of the probe and the sound beam direction; S2, extracting echo signal characteristics and performing joint optimization; s201, performing empirical mode decomposition on the acquired multi-channel original echo signals, separating out high-frequency noise components and structure clutter components, and retaining eigenmode functions containing defect information; S202, constructing a depth-related gain compensation function according to attenuation rules of sound waves in the propagation process of the sound waves in the material, and carrying out point-by-point correction on echo amplitudes of layers with different depths; S203, calculating the maximum similarity offset between echo signals of adjacent probes by adopting a cross-correlation algorithm, and carrying out time axis translation on each channel signal according to the offset so as to align multi-view echoes in phase; s3, three-dimensional imaging of the multi-view synthetic aperture; S301, dividing a region to be detected into three-dimensional voxel grids which are regularly arranged, wherein each voxel unit has unique space coordinates; S302, calculating the round trip sound path from each probe to each voxel unit based on the full focus imaging principle and combining the calibrated probe space parameters, and extracting the amplitude response at the moment from the corresponding channel echo; s303, setting a weighting coefficient according to an included angle between a sound axis of the probe and a connecting line of the voxel center, and carrying out angle weighted superposition on voxel amplitudes from dif