CN-122017035-A - Micro damage detection method based on ultrasonic phased array wake wave interference

CN122017035ACN 122017035 ACN122017035 ACN 122017035ACN-122017035-A

Abstract

A method for detecting micro-damage based on ultrasonic phased array wake wave interference comprises the steps of A, forming a phased ultrasonic field in a detected area by adopting an ultrasonic phased array probe or a group of piezoelectric wafers to form phased emission under an excitation delay rule, B, determining and extracting wake signals by collecting ultrasonic signals from the ultrasonic phased array probe or one piezoelectric wafer through the ultrasonic field, C, measuring wake phase difference change by adopting a stretching method, analyzing the wake signals, calculating the numerical value of waveform expansion coefficients of relative wave velocity change amounts, D, continuously repeating the calculation of the step B and the step C to obtain a plurality of groups of relative wave velocity change amounts, fitting the numerical value of relative wave velocity change amounts, E, repeating the measurement and calculation of the step B and the step C on objects with the same material and the same structure, combining the step D to obtain the size of the micro-damage, and realizing early-stage accurate identification of the micro-damage.

Inventors

ZHAN XIANGLIN
LI MENG

Assignees

中国民航大学

Dates

Publication Date: 20260512
Application Date: 20260129

Claims (6)

1. A method for detecting micro damage based on ultrasonic phased array wake wave interference is characterized by comprising the following steps of adopting an ultrasonic phased array probe or phased emission formed by a group of piezoelectric wafers to form a phased ultrasonic field in a detected area under an excitation delay rule; step B, acquiring ultrasonic signals from an ultrasonic phased array probe or a piezoelectric wafer through a phased ultrasonic field to determine and extract wake signals; Step C, measuring the phase difference change of the wake wave by adopting a stretching method, analyzing the wake wave signal, and calculating the relative wave velocity change quantity, namely the numerical value of the waveform expansion coefficient; step D, continuously repeating the calculation of the step B and the step C by collecting wake signals of the micro-lesions with different sizes to obtain a plurality of groups of relative wave speed variation values, and carrying out numerical fitting on the relative wave speed variation values; And E, repeating the measurement and calculation of the step B and the step C for the objects with the same material and the same structure, and combining the step D to obtain the size of the micro damage.
2. The method for detecting micro-damage based on ultrasonic phased array wake wave interference according to claim 1, wherein the method for forming a phased ultrasonic field in the detected area in step a is that the independent piezoelectric crystal in the ultrasonic phased array probe or the single piezoelectric wafer in a group of piezoelectric wafers are all called array elements, the key of the phased ultrasonic field formation is to precisely control the emission time of the single array elements, when N array elements are excited in a delayed manner, the formed beam deflection angle is gamma, and when the formed beam is focused at the focus P from the center F of the array element group, the excitation delay between the N (n=1, 2,3,..: △τ n = △τ 0 + [c△τ2 0(N – 2n)]/2Ftan 2 γ (1); where Δτ 0 = dsin γ/c, d is the spacing between the elements, γ is the beam deflection angle, c is the speed of sound of ultrasound in the material, N is the total number of excited elements, N is the number of excited elements, and F is the focal length.
3. The method for detecting the micro damage based on the ultrasonic phased array wake wave interference, which is characterized by comprising the following steps of determining and extracting wake wave signals from ultrasonic phased array probes or piezoelectric wafers, wherein wave field u (t) obtained by wavelet superposition of all paths according to a path superposition principle is represented by the following formula: u(t) = Σ M S M (t) (2); Wherein M represents the path of sound beam propagation in the ultrasonic wave field, S M (t) represents the ultrasonic wave which randomly passes through the transmission path M from the excitation point to the signal receiving point, therefore, u (t) comprises a direct wave and a scattered wave, when the mean free path of the scattered wave is smaller than one wavelength, the wave field change is mainly reflected on the phase change, in the propagation process, if the wave speed changes, disturbance tau M is generated in time in one path M in all propagation paths, and the disturbed wave field is expressed as: u M (t) = Σ M S M (t - τ M ) (3); Wherein τ M is the disturbance of ultrasonic wave along a certain propagation path M, τ M is mainly dependent on the propagation path M, which means that the phase change of the wave path is related to the change of M before and after the disturbance, the wake time window is selected to be back for realizing that the wake signal is a superimposed signal formed by scattering generated by passing through the damaged part for many times, thus the wave signal is less interfered by clutter, and the phase difference of the wave waveform of the signal can be accurately distinguished on the selected window.
4. The method for detecting the micro damage based on the ultrasonic phased array wake interference is characterized in that step C adopts a stretching method to measure wake phase difference change, wake signal analysis is carried out, the value of a relative wave velocity change quantity, namely a waveform expansion coefficient, is calculated, the wake waveform obtained in an initial state is taken as a reference waveform and is marked as u 0 (t), the reference waveform is stretched or compressed within a time window [ t A , t B ] by a contraction factor epsilon, a wake signal u 0 [ t (1+epsilon) ] in another state is obtained, the expansion factor epsilon represents the relative wave velocity change of two lines of wake waveforms, and the cross correlation coefficient CC (epsilon) of the two lines of waveform signals is shown as the following formula: CC(ε) =∫t B t A u 0 [t(1+ε)]u 0 (t)dt / {∫t B t A u2 0[t(1+ε)]dt ∫t B t A u2 0(t)dt} 0.5 （4）; Wherein [ t A , t B ] is a time period for intercepting a wake signal from an acquired ultrasonic signal, u 0 (t) is the wake signal acquired in an initial state, epsilon is a contraction factor, and when the cross correlation coefficient CC (epsilon) is the maximum value, the corresponding contraction factor epsilon max is the relative wave velocity variation of two columns of waveforms, and the following formula is shown: ε max = △v / v (5); Wherein Deltav is the wave velocity variation of two rows of waveforms, and v is the wave propagation velocity before the waveform variation; When analysis is carried out, the reference signal and a plurality of groups of disturbance signals are respectively subjected to cross-correlation operation, CC (epsilon max ) obtained by calculation represents the similarity degree of each group of signals, but when the value of CC (epsilon max ) is too small, the measurement by a stretching method is not applicable any more, a gradual wake wave interferometry is introduced for determining the relative speed change, the whole change process of the reference signal and the disturbance signals is not directly compared, the reference signal and the disturbance signals are divided into a plurality of parts, the parts are represented by Q, epsilon i of each part is gradually solved, and finally the total relative speed change quantity is obtained by the following formula: △v / v = [(1-ε 1 ) (1-ε 2 )…(1-ε i )] -1 -1 (6); where ε i is the scaling factor for part i, i=1, 2.
5. The method for detecting the micro-damage based on the ultrasonic phased array wake interference is characterized in that the method in the step D is characterized in that as the external applied tension increases, the micro-damage is gradually formed, the size is continuously increased, the step B and the step C are continuously repeated through collecting wake signals of the micro-damage under different sizes to obtain a plurality of values of v/v, the values of v/v are fitted, and the fitting result shows the relation between the micro-damage in a detected area and wake parameters.
6. The method for detecting the micro damage based on the ultrasonic phased array wake interference is characterized in that the method in the step E is that the measurement and calculation in the step B and the step C are repeated on the objects with the same material and the same structure, the V/V value can be obtained, and the size of the micro damage can be obtained by combining the fitting curve of DeltaV/V obtained in the step D.

Description

Micro damage detection method based on ultrasonic phased array wake wave interference Technical Field The invention relates to the technical field of nondestructive testing, in particular to a micro-damage detection method based on ultrasonic phased array wake interference. Background In the fields of aerospace, energy electricity, rail transit and petrochemical industry, metallic materials (such as aluminum alloys, titanium alloys) and composite materials (such as carbon fiber reinforced polymers) are the main materials for manufacturing components. Such components, such as aircraft skins, pipes, bridges, etc., are exposed to complex and variable environments such as alternating loads, corrosion or temperature changes for a long period of time, are prone to small damage (e.g., microcracks) in the size range of 0.1mm to 1mm, and are prone to gradual expansion along the material stress concentration region. Because the initial size of the micro damage is small and the distribution is dispersed, if the micro damage is not detected in time, the micro damage can be rapidly expanded along the stress concentration area, fatigue fracture is caused, and the operation safety of the structure is seriously threatened. Therefore, early and accurate detection of the micro damage is a key for guaranteeing the structural reliability and realizing early warning of faults, and has important significance for prolonging the service period of the component and optimizing the maintenance cost. At present, nondestructive detection methods for tiny damage mainly comprise conventional detection methods (optical, penetration, X-ray and vortex) and ultrasonic detection methods (traditional ultrasonic, nonlinear ultrasonic and novel ultrasonic), but have certain limitations: 1. Conventional nondestructive testing methods, (1) optical testing, i.e., the detection of microcracks by light reflection or interference principles. The AOI automatic optical detection of CN202111399828.5 and the laser interference technique of CN202310704245.1 can realize a resolution of several tens of micro-nano, but are greatly affected by light intensity, have poor detection effect on members with high surface roughness, and are difficult to detect internal damage. (2) Penetration detection, i.e. penetration of microcracks by penetrating agents, and then observation with naked eyes or a microscope (such as patent CN202110891704.2, CN201910162017. X). The permeation method is simple to operate, but has low detection efficiency. And chemical reagents are needed, which is easy to cause environmental pollution. In addition, deep lesions cannot be detected. (3) The X-ray detection can effectively detect internal microcracks, but has the radiation hazard, and the equipment has large volume and poor maneuverability, and is difficult to adapt to the field detection requirement. (4) Vortex detection, namely non-contact detection, but is only suitable for conductive materials, and has large electromagnetic interference and high false alarm rate. 2. Ultrasonic detection is an important means for detecting micro damage, but the traditional ultrasonic detection method and the existing improved method have obvious defects: (1) Conventional ultrasonic inspection identifies macroscopic defects based on the linear response of the acoustic wave caused by reflection at the defect, with the smallest detectable defect size being about half the wavelength of the ultrasonic wave. However, for small damage, the reflected signal is extremely weak, and early microcracks are difficult to effectively identify. (2) Nonlinear ultrasonic detection, wherein nonlinear ultrasonic parameters can represent tiny damage, but nonlinear signals are easily interfered by instrument noise and microstructure (such as grain boundaries) of the material, so that detection accuracy is reduced. (3) The existing ultrasonic new method comprises electromagnetic ultrasonic (such as patent CN 202210728123.1) and nonlinear acoustic resonance technology, but has low energy conversion efficiency, so that the detection sensitivity of micro cracks is insufficient; laser ultrasonic (as patent CN 202310401042.5) locates microcracks through transmission component change, but the device is complex, the excitation source and the detection position are required to be manually adjusted according to the size of a metal member to be detected, and echo signals are easy to submerge in environmental noise; Acoustic emission techniques (e.g., patent CN 202210866405.8) are used to determine microcracks by collecting acoustic signals, but the signals are weak and subject to external disturbances such as mechanical vibrations, and the propagation paths are variable. 3. Other novel detection methods (1) require special instruments, namely, detection is realized by analyzing mass spectrum characteristic peak information in patent CN201910476251.X, but primary ions are bombarded to a sample and secondary ions are acquired, equipmen