68 results about "Lamb waves" patented technology

A device includes a stack of at least two piezoelectric layers configured to propagate a Lamb wave in a mode having an order corresponding to a number of piezoelectric layers of the stack. The stack includes a first piezoelectric layer and a second piezoelectric layer disposed on the first piezoelectric layer. The first piezoelectric layer has a first cut plane orientation, and the second piezoelectric layer has a second cut plane orientation complementary to the first cut plane orientation. The device further includes an interdigitated transducer (IDT) disposed on at least a top surface of the stack or a bottom surface of the stack. In some embodiments, the device is an acoustic resonator. In some embodiments, the device is an acoustic delay line.

The application discloses a manufacturing method of a resonant filter. The method comprises the following steps: manufacturing a first substrate and a resonant filter structure, wherein the resonant filter structure is formed on a first side of the first substrate, the resonant filter structure comprises a bulk acoustic wave resonant structure and a Lamb wave resonant structure, the bulk acoustic wave resonant structure and the Lamb wave resonant structure are electrically connected, the bulk acoustic wave resonant structure comprises a first electrode structure, the Lamb wave resonant structure comprises a second electrode structure, the second electrode structure comprises a first interdigital electrode and a second interdigital electrode, the first electrode structure and the second electrode structure share a same first electrode layer, the first interdigital electrode is electrically connected with the outside, and the second interdigital electrode is electrically connected with the first electrode structure.

The invention relates to the technical field of feature compression, in particular to a CFRP wing skin damage feature efficient compression method based on functional principal component analysis. Comprising the following steps that S1, sensor signal data of the CFRP wing skin are obtained, and the sensor signal data comprise Lamb wave signals collected by a plurality of sensors at different damage positions; s2, preprocessing the sensor signal to obtain processed high-dimensional time sequence characteristic data; s3, function type principal component analysis compression processing is carried out on the high-dimensional time sequence feature data, the S3 comprises the following steps: S4, significant time points are screened according to the comprehensive scores, and the S4 comprises the following steps: S5, compressed damage feature data are output, the compressed damage feature data only comprise feature values corresponding to the significant time points, and the feature values only comprise feature values corresponding to the significant time points. The method is used for subsequent damage positioning tasks.

The invention discloses an aviation aluminum plate wave field image damage monitoring method based on non-convex total variation regularization RPCA. The method comprises the following steps: acquiring Lamb wave field image data of a to-be-detected aviation aluminum plate by using a sensor array; decomposing the mapped Lamb wave field image data by using a non-convex total variation regularization robust principal component analysis algorithm, and solving sub-problems by using an alternating direction multiplier method to obtain a low-rank matrix representing background wave field information and a sparse matrix representing damage abnormal values; performing post-processing including sparse response normalization processing, adaptive threshold segmentation, connected region filtering and morphological repair on the sparse matrix to extract a damaged region; according to the extracted damage area, the damage condition of the aviation aluminum plate to be detected is evaluated and positioned. According to the invention, the accuracy and real-time performance of damage identification can be improved.

The invention provides a Lamb wave benchmark-free damage imaging method based on adaptive clustering and semantic weighting, and belongs to the technical field of air coupling ultrasonic detection.The Lamb wave benchmark-free damage imaging method comprises the steps that a full-path response signal is collected through orthogonal scanning, a wavelet low-frequency approximation coefficient and a normalized symmetric difference factor are extracted to construct a joint feature vector; and performing unsupervised division of'health-damage 'states on a scanning path by adopting DBSCAN clustering. And semantic tags obtained by clustering are further used as adaptive weights to be embedded into the improved RAPID probability imaging model, and dynamic construction of artifact path suppression and soft reference is realized. In a layering defect detection experiment of the carbon fiber reinforced composite material, compared with a traditional RAPID method, the average size measurement error is reduced by 50.5% under the condition that an independent health reference is completely not needed, the measurement precision of 40 * 20 * 0.05 mm defects in the X / Y direction is improved by 81.7%, the measurement precision of 40 * 20 * 0.05 mm defects in the Y / X direction is improved by 65.5%, and meanwhile 92.3% of boundary artifacts are effectively restrained.

An acoustic wave device for suppressing spurious waves in Lamb waves, and a filter including the same, are provided. The acoustic wave device comprises a support substrate; a piezoelectric substrate supported by the support substrate and defining a first resonator region; and a first resonator and a second resonator disposed in the first resonator region, each comprising a plurality of interdigital transducer (IDT) electrodes and electrically connected to each other. The support substrate includes a first cavity formed beneath the first resonator and a second cavity formed beneath the second resonator, wherein the first cavity and the second cavity are interconnected within the support substrate.

A selective acoustic electromagnetic transducer (400) for a Lamb wave propagation mode of interest propagating in a structure, comprising a circularly shaped magnet (401) and a coil (402) comprising several independent concentric circular portions and a processing unit (403) connected to the ends of each circular portion, the processing unit (403) being configured to generate a composite signal equal to a linear combination of the signals measured on each circular portion, the coefficients of the linear combination being chosen so as to minimize the sensitivity of the coil (402) to a set of Lamb modes excluding the mode of interest. Figure 4a

The application discloses a nonlinear Lamb wave excitation deviation evaluation method and system under dispersion constraint, belongs to the technical field of ultrasonic nondestructive testing and structural health monitoring, and is based on a Rayleigh-Lamb frequency equation and a second-order perturbation theory to construct a second harmonic displacement field model, divides a phase velocity matching mode pair into an intersection type, a longitudinal wave type and a cutoff type; the contraction law of a propagation distance and a mode order on an excitation window is quantitatively analyzed, an excitation tolerance coefficient and a relative gain coefficient are introduced, a two-dimensional quantitative evaluation system of mode pairs is established, three typical mode pairs are divided and are adapted to different detection working conditions, and an aluminum alloy sheet experiment is completed to verify the application. The application adopts the above-mentioned nonlinear Lamb wave excitation deviation evaluation method under dispersion constraint, establishes a standardized mode evaluation system, and significantly improves detection sensitivity and engineering reliability.

This invention discloses a nonlinear Lamb wave detection method for micro-damage in plate structures based on a flexible sensor array, belonging to the field of nondestructive testing technology. The method includes: generating a sinusoidal modulated excitation signal using a Hanning window; extracting nonlinear characteristic parameters reflecting micro-damage in the plate structure from the preprocessed signal using time-frequency analysis and empirical mode decomposition algorithms; generating a fused damage probability map based on compressed sensing theory and the extracted nonlinear characteristic parameters; constructing a damage distribution profile in the thickness direction by analyzing the penetration depth differences of Lamb waves at different frequencies; and automatically quantifying and analyzing the identified damage areas to obtain the damage detection results. This invention aims to achieve early identification and precise localization of micro-damage in plate structures, effectively overcoming the shortcomings of low sensitivity and inaccurate localization in traditional detection methods, and significantly improving detection accuracy, efficiency, and automation.

The invention relates to the technical field of structural health monitoring, in particular to a generalized zero sample regression method for structural cross-domain damage identification, which comprises the following steps: acquiring Lamb wave scattering signals acquired by a piezoelectric sensor array on a to-be-monitored structure, and splicing the Lamb wave scattering signals in sequence to form a damage sample; extracting real damage features of the sample by using a one-dimensional convolutional neural network; reversely mapping the real damage features to a semantic space through a semantic reconstructor to obtain semantic features implying physical attributes; inputting the semantic features as conditions into a generator network, and generating pseudo-damage features consistent with the real features in distribution; and splicing the real damage features and the pseudo damage features to form joint features, and inputting the joint features into a regression device to predict damage physical coordinates. According to the invention, cross-domain damage accurate positioning is realized through double-feature fusion.

The application provides a film bulk acoustic resonator, comprising a substrate, an acoustic reflection structure arranged on one side of the substrate, a bottom electrode arranged on one side of the acoustic reflection structure, a piezoelectric film covering the bottom electrode, and a top electrode arranged on the side of the piezoelectric film away from the bottom electrode, wherein the side of the top electrode away from the piezoelectric film is provided with an interdigital protruding frame, the interdigital protruding frame comprises oppositely arranged first and second protruding frames, at least one pair of interdigital structures are formed by extending the first and second protruding frames towards each other and being spaced apart by a preset distance and being overlapped, and each interdigital structure comprises two interdigital structures spaced apart by a preset distance along the overlapping direction. The application can reflect two or more transverse Rayleigh-Lamb waves to achieve high reflection efficiency and improve the Q value corresponding to the anti-resonance frequency of the resonator. The peeling residue problem caused by the closed loop of the existing protruding frame can be improved.

Provided are an elastic wave device for suppressing clutters in Lamb waves and a filter including the same. An elastic wave device includes: a support substrate; a piezoelectric substrate supported by the support substrate on the support substrate and defining a first resonator region; and a first resonator and a second resonator disposed in the first resonator region of the piezoelectric substrate, each including a plurality of I DT electrodes and electrically connected, the support substrate including a first cavity formed in a lower portion of the first resonator, and a second cavity formed in a lower portion of the second resonator, the first cavity and the second cavity being electrically connected to each other. The first cavity and the second cavity are connected to each other within the support substrate.

The invention provides a cement sheath thickness measurement method, device and equipment and a storage medium, and belongs to the field of applied geophysics and oil-gas exploration, and the measurement method comprises the steps: obtaining full-wave waveform data of a Lamb wave received at different orientations at a certain depth point in a target depth interval; performing waveform processing on the full-wave waveform data of the Lamb wave received at different orientations of the depth point, and determining corresponding group delays of the depth point at different orientations; based on the group delays corresponding to the depth point in different orientations, circumferential cement sheath thicknesses corresponding to the depth point in different orientations are determined; and repeatedly executing the steps until the circumferential cement sheath thickness corresponding to each depth point of the target depth interval in different directions is obtained. Through the method provided by the invention, accurate calculation of the thickness of the cement sheath between the casing and the stratum can be simply and quickly realized, and the well cementation quality can be accurately evaluated.

The application provides a gradient material thickness measurement method and system based on laser ultrasonic dispersion spectrum, and relates to the technical field of laser measurement, and comprises the following steps: modulating excitation laser through an optical mask to form a transient grating with periodic intensity distribution, exciting ultrasonic waves with specific frequencies in a material to be measured by using the transient grating, and receiving Lamb wave signals generated by the structure of the material to be measured by using a laser interferometer for line scanning; performing two-dimensional Fourier transform on the Lamb wave signals to obtain a target dispersion curve; the target dispersion curve comprises a mapping relationship between signal frequencies and wave numbers; a sample pair composed of multiple groups of material thickness parameters and dispersion curve parameters is generated by using a transfer matrix algorithm, and a preset deep neural network is trained based on the sample pair until a loss function reaches a preset threshold range, so that a target neural network is obtained; and the target dispersion curve is input into the target neural network to obtain thickness parameters of the material to be measured.

Provided herein are localized interface-state MEMS devices including a suspended elastic waveguide having a first periodic structure including corrugated elements and a first localized state supporting a first symmetric lamb wave and a first antisymmetric lamb wave; a second periodic structure including corrugated elements and a second localized state supporting a second symmetric lamb wave and a second antisymmetric lamb wave, wherein the first and second symmetric lamb waves and first and second antisymmetric lamb waves counter-propagate, and a topological interface between the first periodic structure and the second periodic structure configured to break a spatial symmetry of the suspended elastic waveguide to create the first and second localized states and cause destructive interference between the counter-propagating first and second symmetric lamb waves and first and second antisymmetric lamb waves at the topological interface, wherein the destructive interference creates a third localized state.

The application discloses a Lamb wave resonator, comprising: a first substrate; a piezoelectric layer, a cavity is formed between the first substrate and the piezoelectric layer, the piezoelectric layer is a C-axis inclined piezoelectric film, the angle of C-axis inclination is 48°-68° or -68°-48° by rotating the C-axis orientation of the piezoelectric film, the piezoelectric layer is suitable for exciting the first-order anti-symmetry mode Lamb wave under the action of a transverse electric field; a first metal electrode layer, comprising a metal electrode array formed by a plurality of positive and negative metal electrodes arranged alternately, the metal electrode array forms a transverse electric field, the first metal electrode layer is formed on the piezoelectric layer, and the direction of the transverse electric field is 70°-90° or -90°-70° with the +X axis direction of the global coordinate system of the C-axis inclined piezoelectric film; wherein the piezoelectric layer excites the A1 vibration mode Lamb wave under the action of the transverse electric field, so that the Lamb wave resonator realizes an electromechanical coupling coefficient greater than 15% under the condition that the resonant frequency is greater than 3 GHz.

The application discloses a Lamb wave acoustic device, a sensor, a micro-particle manipulation device and a manipulation method. The Lamb wave acoustic device comprises an ultrasonic excitation assembly and an ultrasonic transduction assembly. The ultrasonic transduction assembly comprises an excitation piece and a first excitation electrode group. The excitation piece is provided with opposite first excitation areas and second excitation areas. The first excitation electrode group comprises a first electrode and a second electrode. At least the first electrode is an array electrode. The array electrode comprises a plurality of strip electrodes arranged at intervals along a first direction. The first electrode and the second electrode are electrically connected with the ultrasonic excitation assembly. The ultrasonic transduction assembly has a first resonance frequency and / or a second resonance frequency. When the frequency of an excitation electric signal is equal to the first resonance frequency, the excitation piece generates a Lamb wave field. When the frequency of the excitation electric signal is equal to the second resonance frequency, the excitation piece generates a periodic resonance wave field. The Lamb wave acoustic device can easily generate a Lamb wave field or a periodic resonance wave field.

The invention discloses a self-adaptive denoising method in combination with the physical characteristics of frequency mixing lamb waves, and the method comprises the steps: carrying out the interaction excitation of a frequency mixing signal through two columns of fundamental frequency lamb waves and bridge cracks, and collecting and extracting the frequency mixing signal; and secondly, setting a related fitness function according to the physical characteristics of the frequency mixing signal, and carrying out iterative updating by utilizing the constructed fitness function to obtain an optimal parameter. And finally, inputting the optimal parameter into the variational mode decomposition technology, and based on the optimized variational mode decomposition technology, carrying out denoising processing on the frequency mixing signal to obtain a denoised signal. According to the method, interference of high-intensity noise is avoided to the greatest extent, and effective information is reserved for subsequent crack analysis.

A filter comprises a lamb wave resonator that includes a substrate, a piezoelectric layer, an interdigital transducer, and a dielectric layer. The piezoelectric layer is disposed on the substrate, and the interdigital transducer and the dielectric layer are disposed on a side of the piezoelectric layer that is distal from the substrate. The interdigital transducer includes a plurality of first electrode fingers and a plurality of second electrode fingers that are alternately arranged in sequence in a first direction. The first direction intersects extension directions of the first and the second electrode fingers. The dielectric layer includes a first part, and the first part is disposed on a surface of the piezoelectric layer and is located on a periphery of the first electrode fingers and the second electrode fingers.

The present application relates to the technical field of solid plate defect detection, in particular to a solid plate defect detection method based on Lamb wave end face echo, which comprises the following steps: arranging excitation and receiving wedge piezoelectric transducers on the same side of the solid plate, exciting and receiving single mode Lamb wave signals, obtaining multi-path signals containing direct wave, side echo and defect reflection echo, enhancing the identification ability of boundary and local defects, extracting defect reflection signals by analyzing the difference between direct wave and side echo, combining the time difference between the defect reflection signals and the side echo and the Lamb wave propagation speed, establishing a geometric model and accurately calculating the defect position. By adjusting the transducer position to make the time difference between the defect reflection wave and the direct wave constant, the defect echo amplitude is obtained under the condition of equal propagation, compared with the standard test block amplitude, the mapping relationship between amplitude and size is constructed, and the accurate quantification of defect size is realized.

The present disclosure provides an acoustic resonator and a preparation method therefor. The acoustic resonator comprises: a substrate; a piezoelectric layer, prepared on the substrate; a release region, formed between the substrate and the piezoelectric layer and configured for suspended release of the acoustic resonator; a silicon dioxide layer, prepared on the piezoelectric layer and forming a dielectric layer together with the piezoelectric layer; and a metal electrode layer, configured to generate an electric field for exciting Lamb waves to induce acoustic vibration modes in the piezoelectric layer. The thickness of the silicon dioxide layer is adjusted to improve the stress-mode distribution in the piezoelectric layer, thereby enhancing the electromechanical coupling coefficient.

The application discloses a layered defect linear frequency modulation Lamb wave and full convolution network imaging method and system, and belongs to the technical field of neural network imaging methods.The imaging system comprises a plurality of piezoelectric transducers distributed on the surface of a carbon fiber plate to be detected, a channel switcher electrically connected with the piezoelectric transducers, a signal generator capable of generating multi-frequency Lamb waves and an acquisition card electrically connected with the channel switcher; wherein the signal generator adopts a linear frequency modulation mode to excite Lamb waves, the imaging method can receive linear frequency modulation Lamb wave signals through the piezoelectric transducers, extract time-frequency domain features of the linear frequency modulation signals, and then fuse multi-frequency information in the linear frequency modulation Lamb waves through a full convolution neural network and directly output a defect imaging result.

A Lamb wave filter is provided which has improved out of band rejection, the filter including a substrate having a center region and two edge regions, a first set of electrodes arranged as a first interdigital transducer displaced on one of the two edge regions and configured to receive an input signal, a second set of electrodes arranged as a second interdigital transducer displaced on the other of the two edge regions and configured to provide a filtered output signal, and a third set of electrodes disposed parallel to the first and second sets of electrodes on the center region of the substrate.

The invention provides a well cementation quality evaluation and annulus medium propagation velocity determination method and device, and belongs to the field of well cementation quality evaluation.The determination method comprises the steps that waveform data received by a current depth point at different orientations are obtained based on oblique incidence ultrasonic logging, and the waveform data are obtained; the waveform data comprises full-wave waveforms of Lamb waves received by receivers located at different well depths; determining the average propagation time of the reflected wave corresponding to the current depth point in the annulus medium based on the waveform data received by the current depth point at different orientations; and based on the logging parameters and the average propagation time corresponding to the current depth point, determining an annular medium propagation speed corresponding to the current depth point. According to the method provided by the invention, the cement loss in the direction can be identified by independently depending on the propagation velocity of the annulus medium, so that the first-interface and second-interface evaluation of the well cementation quality is realized.

This invention discloses an ultrasonic signal denoising method, apparatus, system, and storage medium, comprising: obtaining the original signal by exciting a Lamb wave on an aluminum plate using an electromagnetic ultrasonic transducer; initially denoising the original signal by utilizing the ability of SVD to extract global correlations, addressing the strong background noise and periodic interference present in the original signal; secondly, to solve the problem of adaptive decomposition and component threshold selection for non-stationary signals, performing EWT adaptive spectrum segmentation on the SVD preprocessed signal and introducing an improved RIME algorithm, using kurtosis as the fitness function to optimize the number of modes in the EWT decomposition, thereby achieving effective extraction of the Empirical Wavelet Mode Function (EWM) of the noisy signal; then, setting a threshold using the standard deviation method to determine the useful and noise components; reconstructing the noise component with the useful component after wavelet threshold denoising to obtain the final denoised signal, thus achieving denoising of the electromagnetic ultrasonic signal.

The invention discloses a Lamb wave resonator and a preparation method thereof, and belongs to the technical field of radio frequency MEMS devices. According to the Lamb wave resonator, before the piezoelectric film layer and the substrate layer are bonded, part of the area of the first side face (namely the back face), close to the substrate layer, of the piezoelectric film layer is thinned, so that a single Lamb wave resonator has multiple working frequencies, and then multi-frequency coverage is achieved under the condition that the size is small. After the operation, the second side surface (namely the surface), far away from the substrate layer, of the piezoelectric film layer is flat, no height difference exists, and the preparation of an interdigital electrode (IDT) can be realized by adopting a conventional photoetching interdigital electrode (IDT) process. Therefore, the preparation of the Lamb wave resonator with multi-frequency coverage can be easily realized.

The application relates to the fields of sensors and nondestructive testing, in particular to a defect detection method and device based on multi-modal Lamb waves. In order to solve the problem that the effective modal signal corresponding to defects is difficult to accurately identify due to the multi-modal characteristics of Lamb waves, a new defect detection method and device based on multi-modal Lamb waves are provided, which comprises the following steps: 1) simultaneously exciting two Lamb waves with different frequencies in a sample; 2) receiving the detection echo of the sample and forming a time domain signal diagram; 3) using a wavelet transform high-efficiency time-frequency analysis method to generate a time-frequency diagram; 4) selecting two frequency values, respectively constructing frequency straight lines parallel to the time axis, and taking the two frequency straight lines as the reference to perform a vertical direction slicing operation on the generated time-frequency diagram, and finally obtaining a slice diagram; 5) analyzing the slice diagram to obtain the position of the defects in the sample. The method can accurately identify and position the defects.

The invention relates to a coating structure thickness measuring method based on a laser ultrasonic zero-group velocity Lamb wave technology, which comprises the following steps: acquiring a frequency domain waveform of a simulation signal in a zero-group velocity Lamb wave of a simulation model, extracting a resonance frequency corresponding to a formant in the frequency domain waveform for calculating a zero-group velocity Lamb wave frequency-thickness product, and establishing a multiple linear regression fitting model; and the resonant frequency of the coating structure sample is collected, the resonant frequency and the total thickness are input into the multiple linear regression fitting model, and the coating thickness and the substrate thickness are obtained. According to the method, key parameters of ZGV Lamb waves are extracted, multiple linear regression and a least square method are combined, linear relations between different coating structure thicknesses and corresponding resonant frequencies and multiple linear models between frequency-thickness products and the thicknesses of all the layers are established, and therefore synchronous quantitative measurement of the thicknesses of all the layers of the coatings is achieved; therefore, the overall quality characteristics of the coating structure are reflected.

The application relates to a bearing damage positioning method based on Lamb wave dispersion mode matching of acoustic emission signals, wherein different frequency band components of original acoustic emission signals with the same frequency interval are obtained; a time of arrival curve is obtained; a theoretical dispersion curve of Lamb wave propagation in a bearing is solved, then a coordinate system is unified with the signal time of arrival curve; the dispersion curve and the time curve are matched through a Pearson correlation coefficient index; a formula is established according to a speed difference and a time difference, and a bearing damage distance is calculated; the sensor is moved by a certain distance to be measured again, and the damage position is determined through the two results. The method of matching the Lamb wave propagation mode can determine the propagation speed of the acoustic emission signals with different frequencies, the accuracy of the time difference positioning method is greatly improved, the bearing damage position can be directly found through a single sensor, the bearing fault diagnosis can be realized without depending on the bearing rotating speed, the installation difficulty can be effectively reduced, and the detection cost can be reduced.

The present invention relates to a volume acoustic component (100) with an annular piezoelectric layer (10) having radius R, thickness d and width b and an electrode arrangement with at least one cathode (12) and at least one anode (11). The annular piezoelectric layer (10) has at least one Lamb-wave mode with propagation direction along the azimuthal direction of the annular piezoelectric layer (10).