Intelligent detection method and system for structural damage based on ultrasonic guided wave phased array regulation

Abstract

The present application relates to the field of ultrasonic guided wave intelligent detection, and relates to a structure damage intelligent detection method and system based on ultrasonic guided wave phased array regulation and control.The present application sequentially emits ultrasonic guided wave signals through each excitation array element on the surface of the to-be-detected structure, collects the receiving signals of each receiving array element, determines a compensation phase factor based on the path distances from each monitoring point to each receiving array element, corrects the receiving signals of each receiving array element based on the compensation phase factor, extracts the amplitude and phase angle thereof, obtains a complex signal set for the same monitoring point on each receiving array element, calculates the coherent superposition sum of each monitoring point and analyzes the coherent energy of each monitoring point, calculates the phase consistency coefficient of each monitoring point based on the phase angle in the complex signal set of each monitoring point, and analyzes the enhanced damage index in combination with the total background energy; identifies damage monitoring points, determines the damage area and damage degree of the to-be-detected structure based on the distribution positions of the damage monitoring points, and improves the detection accuracy.

Description

Technical Field

[0001] This invention relates to the field of intelligent ultrasonic guided wave detection, and specifically to an intelligent method and system for structural damage detection based on ultrasonic guided wave phased array control. Background Technology

[0002] Ultrasonic guided wave testing technology, with its advantages of long propagation distance, wide detection coverage, and single-sided scanning capability, has become the mainstream technique for full-area non-destructive testing of large components such as plates and tubes. Phased array ultrasonic guided waves, through time-division excitation and reception of array elements, can achieve guided wave beam focusing and directional control, significantly improving detection coverage and signal gain compared to traditional single-point ultrasonic testing, and has significant application potential in long-distance damage monitoring of large components.

[0003] However, existing technologies have the following problems: 1. When ultrasonic guided waves propagate in structures such as plates and pipes, there is a severe dispersion effect, which leads to echo phase distortion. Existing technologies still use traditional single compensation methods for deep and long-distance damage in large-sized components, which cannot completely restore phase consistency. After the reflected signal propagates over long distances, the energy is dispersed and the signal-to-noise ratio is extremely low, making it difficult to identify from background noise, resulting in missed detection of minor or early damage.

[0004] 2. Existing damage indices rely solely on the ratio of coherent energy to total background energy for analysis. This ratio is sensitive to signal amplitude. In industrial environments, neglecting phase consistency analysis can lead to artificially high coherent energy in some undamaged areas due to occasional strong noise or sidelobe artifacts, causing the damage index to exceed the threshold and generate false alarms. Summary of the Invention

[0005] This invention aims to address the shortcomings of existing technologies by providing an intelligent structural damage detection method and system based on ultrasonic guided wave phased array control. It corrects dispersion distortion through frequency-domain frequency-by-frequency phase compensation, calculates coherent superposition based on similarity weighting coefficients to improve the signal-to-noise ratio, and then constructs an enhanced damage index by correcting the energy ratio with a phase consistency coefficient, thereby achieving accurate detection and false alarm suppression of weak damage at long distances.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: On the one hand, the present invention provides a method for intelligent detection of structural damage based on ultrasonic guided wave phased array control, comprising: sequentially transmitting ultrasonic guided wave signals through each excitation array element on the surface of the structure under test, acquiring the received signals of each receiving array element, determining a compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, and correcting the received signals of each receiving array element for each monitoring point based on the compensation phase factor.

[0007] The amplitude and phase angle of the phase-corrected received signal are extracted, the complex signals of each received signal are analyzed, the set of complex signals for the same monitoring point on each receiving array element is obtained, and the coherent superposition of each monitoring point is calculated.

[0008] Based on coherent superposition and analysis of the coherent energy of each monitoring point, the phase consistency coefficient of each monitoring point is calculated based on the phase angle in the complex signal set of each monitoring point, and the enhanced damage index of each monitoring point is analyzed by combining the coherent energy and the total background energy.

[0009] Based on the enhanced damage index of each monitoring point, damage monitoring points are identified, and based on the distribution of the damage monitoring points, the damage area and damage degree of the structure under test are determined.

[0010] On the other hand, this invention provides an intelligent structural damage detection system based on ultrasonic guided wave phased array control, comprising: a received signal correction module, a coherent superposition and calculation module, an enhanced damage index analysis module, and a damage severity assessment module. The modules are connected as follows: the received signal correction module is connected to the coherent superposition and calculation module, and the enhanced damage index analysis module is connected to both the damage severity assessment module and the coherent superposition and calculation module.

[0011] The receiving signal correction module sequentially emits ultrasonic guided wave signals through each excitation array element on the surface of the structure under test, collects the received signals of each receiving array element, determines the compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, and corrects the received signals of each receiving array element to each monitoring point based on the compensation phase factor.

[0012] The coherent superposition and calculation module extracts the amplitude and phase angle of the received signal after phase correction, analyzes and obtains the complex signals of each received signal, acquires the set of complex signals for the same monitoring point on each receiving array element, and calculates the coherent superposition of each monitoring point.

[0013] The enhanced damage index analysis module analyzes the coherent energy of each monitoring point based on coherent superposition and phase angle in the complex signal set of each monitoring point. It calculates the phase consistency coefficient of each monitoring point based on the phase angle in the complex signal set of each monitoring point and analyzes the enhanced damage index of each monitoring point by combining the coherent energy and the total background energy.

[0014] The damage assessment module identifies damage monitoring points based on the enhanced damage index of each monitoring point, and determines the damage area and damage level of the structure under test based on the distribution of the damage monitoring points.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention transmits ultrasonic guided wave signals sequentially by each excitation array element on the surface of the structure under test, collects the received signals of each receiving array element, determines the compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, corrects the received signals of each receiving array element for each monitoring point based on the compensation phase factor, eliminates the phase distortion caused by long-distance transmission, and overcomes the defect that traditional single compensation is only suitable for fixed distance frequency.

[0016] (2) This invention extracts the amplitude and phase angle of the received signal after phase correction, analyzes the complex signal of each received signal, obtains the set of complex signals on each receiving array element for the same monitoring point, calculates the coherent superposition of each monitoring point, eliminates the weight deviation caused by the difference in the number of array elements and the propagation distance, ensures that the superposition results of different monitoring points are comparable, strengthens the distinction between damage features and background noise, and further improves the detection capability of weak damage signals.

[0017] (3) Based on coherent superposition and analysis of the coherent energy of each monitoring point, the present invention calculates the phase consistency coefficient of each monitoring point based on the phase angle in the complex signal set of each monitoring point, and combines the coherent energy and the total background energy to analyze the enhanced damage index of each monitoring point, effectively suppressing false alarms caused by occasional strong noise and sidelobe artifacts, and improving the damage identification accuracy in complex industrial sites.

[0018] (4) Based on the enhanced damage index of each monitoring point, the present invention identifies the damage monitoring point, and based on the distribution of the damage monitoring point, determines the damage area and damage degree of the structure to be tested, taking into account both weak damage detection and noise false alarm suppression, avoiding the problem of missed detection and misjudgment by fixed threshold, and providing quantitative data support for the formulation of equipment operation and maintenance and repair cycles. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the method steps of the present invention;

[0021] Figure 2 This is a schematic diagram of the steps for calculating the coherent superposition sum of each monitoring point in this invention;

[0022] Figure 3 This is a schematic diagram of the steps in the analysis method of the enhanced damage index at each monitoring point in this invention.

[0023] Figure 4 This is a schematic diagram of the system module connections of the present invention. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. Furthermore, it should be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale.

[0025] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

[0026] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0027] Please see Figure 1 As shown, the present invention provides a method for intelligent detection of structural damage based on ultrasonic guided wave phased array control, comprising: S1, sequentially emitting ultrasonic guided wave signals through each excitation array element on the surface of the structure under test, acquiring the received signals of each receiving array element, determining a compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, and correcting the received signals of each receiving array element to each monitoring point based on the compensation phase factor.

[0028] Considering the severe dispersion effect of ultrasonic guided waves during propagation in plate and tubular components, the propagation speed of different frequency components varies, and the echo phase is severely distorted after long-distance propagation; at the same time, traditional phase compensation only uses a fixed phase offset, which cannot adapt to different propagation distances and multi-frequency component synchronous distortion scenarios, the signal-to-noise ratio of long-distance damage echoes is greatly attenuated, and the characteristics of minor damage are easily submerged by noise.

[0029] Considering that the distances between each array element and the monitoring point are different, a uniform compensation method would leave a phase deviation. Therefore, the full-band dispersion curve is first solved by material parameters to obtain the wavenumber of each frequency. The phase compensation factor is calculated independently for each frequency, each monitoring point, and each array element. After phase correction is completed in the frequency domain, the inverse Fourier transform is used to restore the time domain signal, eliminating the phase lag distortion caused by dispersion and uniformly eliminating the phase offset error caused by different propagation paths.

[0030] Based on this, the method for correcting the received signal of each receiving array element for each monitoring point includes: S11, obtaining the dispersion curve of the structure in the full frequency band based on the material elastic constant and geometric thickness of the structure under test, and obtaining the wavenumber corresponding to each frequency.

[0031] In a specific embodiment of the present invention, each array element possesses the dual function of transmitting and receiving ultrasonic guided waves. Although the present invention uses excitation array elements to sequentially transmit and collect signals from each receiving array element for functional naming, the physical carrier is a set of co-located piezoelectric sensor arrays. Each piezoelectric array element sequentially acts as an excitation array element to transmit ultrasonic guided wave signals, while the remaining piezoelectric array elements act as receiving array elements to collect and receive signals. In this embodiment, a two-dimensional rectangular grid is used, with the distance between each array element being 1 / 2 of the guided wave wavelength. Each array element uses a circular piezoelectric ceramic sheet, and its resonant frequency is consistent with the center frequency of the guided wave excitation signal.

[0032] Furthermore, the method for obtaining each monitoring point is as follows: a virtual grid is divided on the surface of the structure to be tested according to a set side length, and the intersection of the grid is taken as each monitoring point. In this embodiment, 1cm is used as the set side length, but the implementer can also set other specific values.

[0033] Based on the material elastic constants of the structure under test, such as Young's modulus, Poisson's ratio, density, and geometric thickness, the Rayleigh-Lamb dispersion equation is used to solve for the dispersion curve of the Lamb wave. Specifically, the P-wave velocity and S-wave velocity are first calculated from the material parameters; then, within a preset frequency range, a bisection method is used to search for the phase velocity that satisfies the Rayleigh-Lamb equation frequency by frequency, ensuring that the equation residual is less than 10. -6 The solution is taken as the phase velocity value at that frequency; finally, according to Calculate the wavenumber corresponding to each frequency, where The value is the phase velocity. The Rayleigh-Lamb dispersion equation is existing technology and will not be described in detail here.

[0034] S12. Calculate the compensation phase factor for each receiving element relative to each monitoring point by multiplying the wavenumber corresponding to each frequency and the path distance from each monitoring point to each receiving element. The phase compensation factor is used to compensate for the phase lag caused by dispersion effects during the propagation of the ultrasonic guided wave from the monitoring point to the receiving element; its specific form is as follows: .

[0035] in The imaginary unit, Let be the compensation phase factor of the i-th receiving array element for the r-th monitoring point in each frequency band. The wave number corresponding to each frequency. Let be the distance from the i-th receiving element to the r-th monitoring point. This form is existing technology and will not be described in detail here.

[0036] S13. Multiply the compensation phase factor of each receiving array element for each monitoring point with the spectrum of the received signal in the frequency domain to obtain the phase-corrected frequency domain signal for each monitoring point. Then, obtain the phase-corrected received signal through transformation. The transformation to obtain the phase-corrected received signal refers to converting the frequency domain signal into a time domain signal through inverse Fourier transform. This process is existing technology and will not be described in detail here.

[0037] This invention involves sequentially emitting ultrasonic guided wave signals from each excitation array element on the surface of the structure under test, acquiring the received signals from each receiving array element, determining the compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, and correcting the received signals of each receiving array element to each monitoring point based on the compensation phase factor, thereby eliminating phase distortion caused by long-distance transmission and overcoming the shortcomings of traditional single compensation that is only suitable for fixed distance frequencies.

[0038] S2. Obtain the complex signals of each received signal, construct the initial complex signal, and calculate the coherent superposition of each monitoring point.

[0039] Considering the large differences in amplitude and phase dispersion of complex signals of each array element after phase correction, direct equal-weighted vector superposition will be affected by noise array elements and sidelobe artifact signals, reducing the coherence gain. Different excitation and receiving array elements have different propagation path lengths, and indiscriminate superposition will result in excessively high near-field signal weights and dilution of weak far-field damage signals.

[0040] Furthermore, considering that relying solely on phase values ​​cannot distinguish between effective damaged coherent signals and random noise phases, this invention introduces phase similarity to construct normalized similarity weighting coefficients. This assigns higher weights to effective signals with high phase consistency and reduces the weights to noise discrete phase signals. By performing weighted vector summation, coherent superposition is obtained, which weakens random noise interference, amplifies the coherent gain of the array signal in the damaged area, and uniformly eliminates the superposition weight deviation caused by array element spacing and propagation distance, ensuring that the calculation results of all monitoring points can be compared horizontally.

[0041] Based on this, the specific implementation steps of S2 include: S21, extracting the amplitude and phase angle of the phase-corrected received signal, analyzing to obtain the complex signal of each received signal, and obtaining the set of complex signals for the same monitoring point on each receiving array element. The specific implementation steps include: S211, using the cosine value of the phase angle of the phase-corrected received signal of each receiving array element for each monitoring point as the real part, and using the sine value of the phase angle as the imaginary part to construct the initial complex signal.

[0042] S212. The complex signals of each received signal are obtained by multiplying the amplitude of the initial complex signal with the amplitude of the phase-corrected received signal.

[0043] S213. Statistically analyze the complex signals corresponding to the receiving array elements at each monitoring point under the transmitted signals of each excitation array element, and form them into a complex signal set.

[0044] S22. Calculate the coherent superposition sum of each monitoring point. For example... Figure 2 As shown, the specific implementation steps include: S221, extracting the phase angles of all received signals on each receiving element under the transmitted signal of the same excitation element from the complex signal set of each monitoring point. The receiving elements are all piezoelectric elements except the current excitation element.

[0045] S222. Calculate the absolute difference of the phase angle in the received signals of every two receiving array elements, and record it as the phase difference. Calculate the phase similarity based on the phase difference.

[0046] Specifically, if the phase difference is less than or equal to π, the ratio of the phase difference to π is recorded as the deviation degree; if the phase difference is greater than π, the difference between 2π and the phase difference is obtained, and the ratio of this difference to π is recorded as the deviation degree; the difference between 1 and the deviation degree is recorded as the phase similarity degree.

[0047] S223. Based on phase similarity analysis, the similarity weighting coefficients of each complex signal are calculated by multiplying the complex signals of each monitoring point on each receiving array element with the corresponding similarity weighting coefficients to obtain the weighted complex signal. In this embodiment, the analysis method for the similarity weighting coefficients includes: W1. Recording the received signals of two array elements with a phase similarity greater than a set similarity threshold as phase-similar signals. In this embodiment, the similarity threshold is set to 0.8, but the implementer can also set other specific values.

[0048] W2. Count the number of array elements corresponding to phase-similar signals of the received signals on each receiving array element under the same excitation array element's transmitted signal at each monitoring point. Record the ratio of this ratio to the total number of remaining receiving array elements excluding the current excitation array element as the similarity weighting coefficient for the corresponding receiving array element. The total number of remaining receiving array elements is the total number of array elements minus one.

[0049] W3. The difference between the maximum and minimum values ​​of the similarity weighting coefficients of the received signals on each receiving element under the same excitation element at each monitoring point is recorded as the range.

[0050] W4. Calculate the difference between the similarity weighting coefficient of each receiving array element and the minimum value, and record the ratio of this difference to the range as the normalized similarity weighting coefficient.

[0051] S224. The vector summation of the weighted complex signals of all excitation array elements is performed to obtain the coherent superposition of each monitoring point.

[0052] This invention extracts the amplitude and phase angle of the received signal after phase correction, analyzes the complex signals of each received signal, obtains the set of complex signals on each receiving array element for the same monitoring point, calculates the coherent superposition of each monitoring point, eliminates the weight bias caused by the difference in the number of array elements and the propagation distance, ensures the comparability of the superposition results of different monitoring points, strengthens the distinction between damage features and background noise, and further improves the detection capability of weak damage signals.

[0053] S3. Based on coherent superposition and analysis of the coherent energy of each monitoring point, the phase consistency coefficient of each monitoring point is calculated based on the phase angle in the complex signal set of each monitoring point, and the enhanced damage index of each monitoring point is analyzed by combining the coherent energy and the total background energy.

[0054] Considering that the traditional damage index only uses the ratio of coherent energy to background energy as the evaluation criterion, and is only sensitive to signal amplitude; there are occasional strong noises such as mechanical vibration, electromagnetic interference, and array sidelobe artifacts in industrial sites, and instantaneous high coherent energy is likely to appear in undamaged areas, so relying solely on the energy ratio will generate a large number of false alarms.

[0055] Furthermore, considering that the phase of the array echo in the damaged area is highly consistent, while the phase of the noise signal is randomly distributed, it is impossible to distinguish between high-energy noise and real damage echoes based solely on energy. Therefore, this invention integrates the circumferential statistical synthesis vector length and phase entropy to construct a phase consistency coefficient, quantifies the phase concentration of the array signal, and multiplies the phase consistency coefficient by the energy ratio to obtain an enhanced damage index. At the same time, it constrains both amplitude and phase characteristics, and only when the energy is high and the phase is highly uniform is it judged as a high damage index, effectively suppressing false alarms caused by noise and sidelobes, and improving the sensitivity of early minor damage identification.

[0056] Based on this, such as Figure 3 As shown, the specific implementation steps of S3 include: S31, mapping the phase angles of all receiving array elements corresponding to each monitoring point to a circular interval to obtain a circular sample set, and calculating the composite vector length of the circular sample set. The circular interval is [-π, π]. The formula for calculating the composite vector length is as follows:

[0057] ;

[0058] in Represents the length of the composite vector. The total number of samples in the circular sample set. Let be the phase angle of the k-th received signal, where k = 1, 2, 3, ..., N.

[0059] S32. Divide the circular interval into equal parts according to the set number of sub-intervals, obtain the distribution probability of each sub-interval, calculate the phase entropy of the circular sample set based on the distribution probability of each sub-interval, and fuse the synthetic vector length and phase entropy to obtain the phase consistency coefficient of each monitoring point.

[0060] The formula for calculating the phase entropy is as follows:

[0061] ;

[0062] in Represents the phase entropy, m=1,2,3...,M; This represents the number of intervals. In this embodiment, it is divided into 36 sub-intervals. Implementers can also set other specific values ​​according to actual conditions. This represents the probability distribution of each subinterval.

[0063] S33. The square of the modulus of the coherent superposition of each monitoring point is denoted as the coherent energy, and the sum of the squares of the modulus of each complex signal in the complex signal set of each monitoring point is denoted as the total energy received by the array element.

[0064] S34. Calculate the ratio of coherent energy to the total energy received by the array elements, and multiply it by the phase consistency coefficient as the enhancement damage index for each monitoring point.

[0065] This invention is based on coherent superposition and analysis of the coherent energy of each monitoring point. It calculates the phase consistency coefficient of each monitoring point based on the phase angle in the complex signal set of each monitoring point, and combines the coherent energy with the total background energy to analyze the enhanced damage index of each monitoring point. This effectively suppresses false alarms caused by occasional strong noise and sidelobe artifacts, and improves the damage identification accuracy in complex industrial sites.

[0066] S4. Based on the enhanced damage index of each monitoring point, identify the damage monitoring points, and based on the distribution of the damage monitoring points, determine the damage area and damage degree of the structure under test.

[0067] Considering that fixed damage thresholds cannot be adapted to components of different sizes and materials, a globally uniform threshold is prone to missing small damages and misjudging strong noise; discrete damage monitoring points cannot reflect the actual continuous area of ​​damage when judged individually, and single-point damage index cannot quantify the overall severity of damage to the component.

[0068] Considering the inherent subjectivity of manually selecting thresholds and the low efficiency of threshold adaptation in batch detection scenarios, this invention employs an iterative adaptive threshold algorithm to converge and obtain the optimal damage judgment threshold. It then uses spatial clustering to merge adjacent damage monitoring points into continuous damage clusters, defining the actual damage area with the smallest circumscribed convex polygon. Simultaneously, it combines the damage area proportion and the maximum damage degree at a single point to construct a quantitative damage severity index, quantifying the damage location, damage range, and damage severity output. This avoids missed detections and misjudgments caused by fixed thresholds, providing standardized quantitative data for equipment maintenance and life assessment.

[0069] The method for determining the damage area of ​​the structure under test based on this includes: S41, mapping the enhanced damage index of each monitoring point according to the spatial location of the monitoring point, constructing a distribution map of the enhanced damage index on the surface of the structure under test, and obtaining the average value of the enhanced damage index of all monitoring points as the initial damage threshold.

[0070] S42. Based on the initial damage threshold and the enhanced damage index of each monitoring point, a stepwise analysis is performed to determine the final damage threshold. Each monitoring point whose enhanced damage index is greater than the final damage threshold is recorded as a damage monitoring point.

[0071] The method for determining the final damage threshold includes: S421, based on the initial damage threshold, recording each monitoring point where the enhanced damage index is greater than the initial damage threshold as a point above the threshold, and recording each monitoring point where the enhanced damage index is less than the initial damage threshold as a point below the threshold.

[0072] S422. Obtain the average value of each point above the threshold and the average value of each point below the threshold. Record the average value of the points above the threshold and the average value of each point below the threshold as the new damage threshold.

[0073] S423. Repeat the above steps based on the new damage threshold until the relative change of the new damage threshold is less than the preset convergence threshold, and record it as the final damage threshold. Specifically, based on the new damage threshold, each monitoring point where the enhanced damage index is less than the new damage threshold is recorded as a point below the threshold, and each monitoring point where the enhanced damage index is greater than the new damage threshold is recorded as a point above the threshold. Obtain the average value of each point above the threshold and the average value of each point below the threshold. Record the average value of the average value of the points above the threshold and the average value of each point below the threshold as the new damage threshold. Continue in this manner until the relative change of the new damage threshold from the previous new damage threshold is less than 1% of the new damage threshold, and then use the current new damage threshold as the final damage threshold.

[0074] S43. Based on the distribution map of the enhanced damage index, perform spatial cluster analysis on the damage monitoring points and group spatially adjacent damage monitoring points into the same damage cluster.

[0075] S44. The region contained in the smallest circumscribed convex polygon of each damage cluster is determined as each damage region.

[0076] Furthermore, the method for analyzing the degree of damage includes: T1, obtaining the ratio of the enhanced damage index of each damage monitoring point to the minimum value of the enhanced damage index, and recording this ratio as the degree of damage at each monitoring point. Specifically, the minimum value of the enhanced damage index can be considered as a reference value for no damage; when the minimum value of the enhanced damage index is zero, the smallest non-zero value is used as a benchmark value, and the ratio of the enhanced damage index of each damage monitoring point to the benchmark value is calculated, and recorded as the degree of damage at each monitoring point.

[0077] T2. Obtain the sum of the areas of each damaged region, and record the ratio of this sum to the total area of ​​the surface of the structure to be tested as the damage range. The product of this sum and the maximum damage value among all monitoring points in all damaged regions is recorded as the damage degree of the structure to be tested.

[0078] This invention identifies damage monitoring points based on the enhanced damage index of each monitoring point. Based on the distribution of the damage monitoring points, it determines the damage area and degree of damage of the structure under test. It takes into account both the detection of weak damage and the suppression of false alarms due to noise, avoids the problems of missed detection and misjudgment due to fixed thresholds, and provides quantitative data support for the formulation of equipment operation and maintenance and repair cycles.

[0079] like Figure 4 As shown, on the other hand, the present invention provides an intelligent structural damage detection system based on ultrasonic guided wave phased array control, comprising: a received signal correction module, a coherent superposition and calculation module, an enhanced damage index analysis module, and a damage degree assessment module. The modules are connected as follows: the received signal correction module is connected to the coherent superposition and calculation module, and the enhanced damage index analysis module is connected to both the damage degree assessment module and the coherent superposition and calculation module.

[0080] The receiving signal correction module sequentially emits ultrasonic guided wave signals through each excitation array element on the surface of the structure under test, collects the received signals of each receiving array element, determines the compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, and corrects the received signals of each receiving array element to each monitoring point based on the compensation phase factor.

[0081] The coherent superposition and calculation module extracts the amplitude and phase angle of the received signal after phase correction, analyzes and obtains the complex signals of each received signal, acquires the set of complex signals for the same monitoring point on each receiving array element, and calculates the coherent superposition of each monitoring point.

[0082] The enhanced damage index analysis module analyzes the coherent energy of each monitoring point based on coherent superposition and phase angle in the complex signal set of each monitoring point. It calculates the phase consistency coefficient of each monitoring point based on the phase angle in the complex signal set of each monitoring point and analyzes the enhanced damage index of each monitoring point by combining the coherent energy and the total background energy.

[0083] The damage assessment module identifies damage monitoring points based on the enhanced damage index of each monitoring point, and determines the damage area and damage level of the structure under test based on the distribution of the damage monitoring points.

[0084] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0085] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0086] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0087] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0088] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for intelligent detection of structural damage based on ultrasonic guided wave phased array control, characterized in that, include: The ultrasonic guided wave signal is emitted sequentially by each excitation array element on the surface of the structure under test, and the received signal of each receiving array element is collected. Based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, the compensation phase factor is determined, and the received signal of each receiving array element to each monitoring point is corrected based on the compensation phase factor. The amplitude and phase angle of the phase-corrected received signal are extracted, the complex signals of each received signal are analyzed, the set of complex signals for the same monitoring point on each receiving array element is obtained, and the coherent superposition of each monitoring point is calculated. Based on coherent superposition and analysis of the coherent energy of each monitoring point, the phase consistency coefficient of each monitoring point is calculated based on the phase angle in the complex signal set of each monitoring point, and the enhanced damage index of each monitoring point is analyzed by combining the coherent energy and the total background energy. Based on the enhanced damage index of each monitoring point, damage monitoring points are identified, and based on the distribution of the damage monitoring points, the damage area and damage degree of the structure under test are determined.

2. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 1, characterized in that, The method for correcting the received signal of each receiving array element for each monitoring point includes: Based on the material elastic constants and geometric thickness of the structure under test, the dispersion curve of the structure in the full frequency band is obtained, and the wave number corresponding to each frequency is obtained. The compensation phase factor of each receiving array element for each monitoring point is determined by multiplying the wavenumber corresponding to each frequency and the path distance from each monitoring point to each receiving array element. The compensation phase factor of each receiving array element for each monitoring point is multiplied in the frequency domain with the spectrum of the received signal to obtain the phase-corrected frequency domain signal for each monitoring point, and then the phase-corrected received signal is obtained by transformation.

3. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 2, characterized in that, The method for obtaining the complex signal set includes: The cosine of the phase angle of the received signal after phase correction for each receiving array element at each monitoring point is used as the real part, and the sine of the phase angle is used as the imaginary part to construct the initial complex signal. The complex signals of each received signal are obtained by multiplying the amplitude of the initial complex signal with the amplitude of the phase-corrected received signal. The complex signals corresponding to the transmitted signals of each excitation array element at each monitoring point are statistically analyzed and formed into a complex signal set.

4. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 3, characterized in that, The calculation method for the coherent superposition sum of the monitoring points includes: Extract the phase angle of all received signals on each receiving element under the transmitted signal of the same excitation array element from the complex signal set of each monitoring point; Calculate the absolute difference of the phase angle in the received signals on every two receiving array elements, record it as the phase difference, and calculate the phase similarity based on the phase difference; Based on the phase similarity analysis of the similarity weighting coefficients of each complex signal, the complex signal of each monitoring point on each receiving array element is multiplied with the corresponding similarity weighting coefficient to obtain the weighted complex signal; The vector summation of the weighted complex signals transmitted by all excitation array elements is obtained by vector summation of the signals at each monitoring point.

5. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 4, characterized in that, The analysis method for the similarity weighting coefficient includes: The received signals of two array elements with a phase similarity greater than a set similarity threshold are denoted as phase similar signals; The number of array elements corresponding to phase-similar signals of the received signals on each receiving array element under the same excitation array element's transmitted signal at each monitoring point is counted, and the ratio of this number to the total number of remaining receiving array elements excluding the current excitation array element is recorded as the similarity weighting coefficient of the corresponding receiving array element. The difference between the maximum and minimum values ​​of the similarity weighting coefficients of the received signals on each receiving element under the same excitation element at each monitoring point is recorded as the range. Calculate the difference between the similarity weighting coefficient of each receiving array element and the minimum value, and record the ratio of this difference to the range as the normalized similarity weighting coefficient.

6. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 1, characterized in that, The analysis methods for the enhanced damage index at each monitoring point include: The phase angles of all receiving array elements corresponding to each monitoring point are mapped to the circumferential interval to obtain a circular sample set, and the composite vector length of the circular sample set is calculated. The circular interval is divided into equal parts according to a set number of sub-intervals, and the distribution probability of each sub-interval is obtained. The phase entropy of the circular sample set is calculated based on the distribution probability of each sub-interval. The composite vector length and phase entropy are fused and calculated to obtain the phase consistency coefficient of each monitoring point. The square of the modulus of the coherent superposition of each monitoring point is denoted as the coherent energy, and the sum of the squares of the modulus of each complex signal in the complex signal set of each monitoring point is denoted as the total energy received by the array element. The ratio of coherent energy to the total energy received by the array elements is calculated, and its product with the phase consistency coefficient is recorded as the enhanced damage index for each monitoring point.

7. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 1, characterized in that, The method for determining the damaged region of the structure under test includes: The enhanced damage index of each monitoring point is mapped according to the spatial location of the monitoring point to construct the distribution map of the enhanced damage index of the surface of the structure to be tested, and the average value of the enhanced damage index of all monitoring points is obtained as the initial damage threshold. The final damage threshold is determined step by step based on the initial damage threshold and the enhanced damage index of each monitoring point. Each monitoring point whose enhanced damage index is greater than the final damage threshold is recorded as a damage monitoring point. Spatial clustering analysis was performed on the damage monitoring points based on the enhanced damage index distribution map, and spatially adjacent damage monitoring points were grouped into the same damage cluster. The region encompassed by the smallest circumscribed convex polygon of each damage cluster is defined as the damage region.

8. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 7, characterized in that, The method for determining the final damage threshold includes: Based on the initial damage threshold, each monitoring point with an enhanced damage index greater than the initial damage threshold is recorded as a point above the threshold, and each monitoring point with an enhanced damage index less than the initial damage threshold is recorded as a point below the threshold. Obtain the average value of each point above the threshold and the average value of each point below the threshold, and record the average value of the average value of the points above the threshold and the average value of each point below the threshold as the new damage threshold; Repeat the above steps based on the new damage threshold until the relative change in the new damage threshold is less than the preset convergence threshold, and record it as the final damage threshold.

9. The intelligent structural damage detection method based on ultrasonic guided wave phased array control according to claim 1, characterized in that, The methods for analyzing the degree of damage include: The ratio of the enhanced damage index of each damage monitoring point to the minimum value of the enhanced damage index is recorded as the damage degree of each monitoring point. The sum of the areas of each damaged region is obtained, and the ratio of this sum to the total area of ​​the surface of the structure to be tested is recorded as the damage range. The product of this sum and the maximum damage value among all monitoring points in all damaged regions is recorded as the damage degree of the structure to be tested.

10. A structural damage intelligent detection system based on ultrasonic guided wave phased array control, characterized in that, include: The receiving signal correction module sequentially emits ultrasonic guided wave signals through each excitation array element on the surface of the structure under test, collects the received signals of each receiving array element, determines the compensation phase factor based on the path distance from each monitoring point on the surface of the structure under test to each receiving array element, and corrects the received signals of each receiving array element to each monitoring point based on the compensation phase factor. The coherent superposition and calculation module extracts the amplitude and phase angle of the phase-corrected received signal, analyzes and obtains the complex signals of each received signal, obtains the set of complex signals for the same monitoring point on each receiving array element, and calculates the coherent superposition of each monitoring point. The enhanced damage index analysis module analyzes the coherent energy of each monitoring point based on coherent superposition and phase angle in the complex signal set of each monitoring point, calculates the phase consistency coefficient of each monitoring point, and analyzes the enhanced damage index of each monitoring point by combining coherent energy and total background energy. The damage assessment module identifies damage monitoring points based on the enhanced damage index of each monitoring point, and determines the damage area and damage level of the structure under test based on the distribution of the damage monitoring points.

Images