Showing papers on "Lamb waves published in 2022"
TL;DR: The results show that the proposed technique can accurately detect and classify the fatigue damage in composite structures, while removing the need for manual or signal processing-based damage sensitive feature extraction from ultrasonic signals for damage diagnosis.
34 citations
TL;DR: An attempt is made to interpret the 1D CNN model in terms of damage feature contributions using Local Interpretable Model-Agnostic Explanations (LIME) and find that the interpretation corresponds to insightful damage signature.
33 citations
TL;DR: Based on the virtual time reversal technique, the dispersive wave packets adaptively back propagate according to their respective propagation distances so that the dispersion can be completely compensated and focusing signals are obtained.
29 citations
TL;DR: In this paper , a robust automatic damage diagnosis technique that uses ultrasonic Lamb waves and a deep autoencoder (DAE) to detect and classify fatigue damage in composite structures is presented.
28 citations
TL;DR: In this article , a 1D CNN was used for automated damage detection using Lamb wave response of a thin aluminium plate, which achieved around 100% accuracy with around 7% deviation from actual damage localization.
25 citations
TL;DR: Based on the virtual time reversal technique, the dispersive wave packets adaptively back propagate according to their respective propagation distances so that the dispersion can be completely compensated and focusing signals are obtained as discussed by the authors .
21 citations
TL;DR: In this article , a nonlinear ultrasonic method based on the nonlinear Lamb wave principle is proposed by establishing an inspection platform for the aluminum alloy board with 3'mm thickness under the different fatigue tensile cycles.
Abstract: The incipient defect is difficult to be identified by ultrasonic signal analysis. The nonlinear ultrasonic method based on the nonlinear Lamb wave principle is proposed by establishing a nonlinear Lamb wave ultrasonic inspection platform. The optimal Lamb wave parameters are obtained for the incipient fatigue material defects. The aluminum alloy board with 3 mm thickness under the different fatigue tensile cycles is tested. The nonlinear ultrasonic signals are analyzed to obtain second harmonic signals. The intelligent diagnosis method for incipient material degrade is proposed based on the Sequential Probability Ratio Test (SPRT). The sequential probabilistic ratio test (SPRT) algorithm is carried out to classify and identify the second harmonics of four different fatigue damages. The results show that the method about with nonlinear Lamb wave analysis with SPRT is effective and reliable for the incipient material microdefect degradation.
20 citations
TL;DR: In this paper, the authors investigate two-dimensional phononic metaplates consisting of a periodic array of cups on a thin epoxy plate that is perforated with periodic cross holes.
18 citations
TL;DR: In the present method, the point-by-point scan is replaced by a single measurement for FRF with the “Single Input, Multiple Output” (SIMO) mode, which ensures the scan work can be established in N times excitations, which means the excitation waveform can be virtually selected and changed after recording.
16 citations
TL;DR: In this paper, a self-reference broadband version of the LWE technique is proposed, where the broadband vibrations are injected using low-power piezoelectric actuators (sine sweep signal) or using pulsed laser excitation in the thermoelastic regime.
14 citations
TL;DR: In this paper, a hierarchical probabilistic model for Lamb wave detection is formulated in the Bayesian framework, where uncertainties from the model choice, model parameters, and other variables can be explicitly incorporated using the proposed method.
TL;DR: Wang et al. as mentioned in this paper proposed a modified minimum variance method, where waveform information was integrated into algorithm imaging procedure to improve the performance of image reconstruction and localization. But, this method is not suitable for low-resolution images.
Abstract: Lamb wave minimum variance imaging is a promising method for visual damage identification and localization with a sparse transducer array. Imaging performance of minimum variance is highly dependent on the design accuracy of look-direction to describe amplitude relationship of array reflection signals. Look-direction is the combination of a directivity reflection pattern and an attenuation with propagation distance. However, reflection pattern is closely related to damage parameters (e.g. type, orientation and size) and these parameters are usually unknown beforehand. Therefore, accurate design of look-direction is difficult or even impossible, and design error can significantly degrade imaging performance. To overcome this limitation, a modified minimum variance method is proposed in this study. Besides amplitude information, waveform information is integrated into algorithm imaging procedure. Correlation coefficient between local signal and excitation waveform is calculated to generate the distribution of weights for diagonal loading. Diagonal loading weight is an adjustable coefficient in minimum variance algorithm to control the tolerance for look-direction error. With larger weights for potential damage locations, tolerance for inaccuracy in look-direction is increased, and imaging performance is accordingly improved. Experiments on both aluminum plates and composite laminates are carried out to demonstrate the performance improvement of modified method.
TL;DR: Wang et al. as mentioned in this paper proposed a modified minimum variance method, where waveform information was integrated into algorithm imaging procedure to improve the performance of the LW imaging with a sparse transducer array.
Abstract: Lamb wave minimum variance imaging is a promising method for visual damage identification and localization with a sparse transducer array. Imaging performance of minimum variance is highly dependent on the design accuracy of look-direction to describe amplitude relationship of array reflection signals. Look-direction is the combination of a directivity reflection pattern and an attenuation with propagation distance. However, reflection pattern is closely related to damage parameters (e.g. type, orientation and size) and these parameters are usually unknown beforehand. Therefore, accurate design of look-direction is difficult or even impossible, and design error can significantly degrade imaging performance. To overcome this limitation, a modified minimum variance method is proposed in this study. Besides amplitude information, waveform information is integrated into algorithm imaging procedure. Correlation coefficient between local signal and excitation waveform is calculated to generate the distribution of weights for diagonal loading. Diagonal loading weight is an adjustable coefficient in minimum variance algorithm to control the tolerance for look-direction error. With larger weights for potential damage locations, tolerance for inaccuracy in look-direction is increased, and imaging performance is accordingly improved. Experiments on both aluminum plates and composite laminates are carried out to demonstrate the performance improvement of modified method.
TL;DR: In this paper , a novel theory for the perfect transmission through solid-solid interfaces and a unique nonresonant anisotropic single-phase metamaterial realizing the theory was proposed.
TL;DR: In this article , a novel mode of signal processing for the piezoelectric phased array is proposed based on the Frequency Response Function (FRF), where the point-by-point scan is replaced by a single measurement for FRF with the Single Input, Multiple Output (SIMO) mode, which ensures the scan work can be established in N times excitations (N is the number of pieziolectric wafer, much smaller than the amount of inspection points).
TL;DR: In this article , a structural health monitoring (SHM) technique has been developed that could monitor a structure at any time by using a network of sensors, which can generate and sense Lamb waves travelling in the structure.
Abstract: Abstract The most common researched area of damage in a composite material such as carbon fibre reinforced plastics (CFRP) used currently in aircraft construction is barely visible impact damage (BVID), significantly reducing mechanical properties. Early detection and qualification would improve safety and reduce the cost of repair. In this context, structural health monitoring (SHM) techniques have been developed that could monitor a structure at any time by using a network of sensors. Widely used discrete ceramic transducers can generate and sense Lamb waves travelling in the structure. Wave propagation must then be analysed for effective damage identification. An effective SHM system is desired to meet several demands, such as minimised weight penalty, non-intrusive system not interfering with the structure performance, cost-effectiveness for implementation with targeted sensitivity and area coverage, capability of monitoring non-accessible and critical hot spot regions, robustness, and reliability. This review starts with an introduction on Lamb waves fundamentals and their use in SHM, and then particularly focuses on methods using piezoelectric transducers and mode selection. Some relevant applications on different structural configurations are discussed. Finally, recent developments on piezoelectric coating and direct-write sensor technology for tailored transducers are highlighted with some thoughts for near future research work.
TL;DR: In this article , a series of parametric case studies are carried out using the three-dimensional finite element (FE) method to investigate the effects of the excitation frequencies and time delay of the incident waves in wave mixing on the transient response of a weakly-nonlinear material.
TL;DR: In this paper, the authors identified fatigue cracks in a steel joint under vibration by nonlinear guided waves based on second harmonic generation, where piezoelectric transducers were used to excite S1 Lamb wave mode in experiment and the nonlinear ultrasonic testing was performed at different crack lengths.
TL;DR: Wang et al. as discussed by the authors proposed a broadband Lamb wave deep learning algorithm for damage localization and quantification, which can extract damage features from different perspectives, and fusion of all extraction results facilitates the full utilization of rich broadband information.
TL;DR: In this paper , a two-dimensional incipient damage localization method is proposed based on the newly discovered wave phenomenon, where damage-induced nonlinear wave scattering features are first investigated.
TL;DR: In this paper , a non-perforated resonant elastic metamaterial was proposed to achieve the complete conversion of Lamb waves (A0 and S0) into the fundamental shear horizontal (SH0) wave.
TL;DR: Wang et al. as mentioned in this paper proposed a broadband Lamb wave deep learning algorithm for damage localization and quantification, which can extract damage features from different perspectives, and fusion of all extraction results facilitates the full utilization of rich broadband information.
TL;DR: In this article, a non-perforated resonant elastic metamaterial was proposed to achieve the complete conversion of Lamb waves (A0 and S0) into the fundamental shear horizontal (SH0) wave.
TL;DR: In this paper, a two-dimensional incipient damage localization method is proposed based on the newly discovered wave phenomenon, where damage-induced nonlinear wave scattering features are first investigated.
TL;DR: In this paper, an NDE method based on the Lamb wave propagation for the inspection of coated structures was developed and solved analytically, considering different thicknesses and a range of material properties decay for the substrate and coating.
TL;DR: In this article , a piezoelectric bimorph plate connected to a periodic arrangement of electric circuits is proposed, and both propagating and evanescent guided Lamb waves are investigated through the complex band structure resulting form using different shunting capacitor or inductor distributions.
TL;DR: In this paper , a weighted delay-and-sum (DAS) imaging method based on denoising autoencoder (DAE) learning is developed for complex composite structures.
TL;DR: In this article, the presence of combined frequency wave due to contact acoustic nonlinearity is used to detect debonding at the adhesive joint using a nonlinear Lamb wave mixing approach.
Abstract: Many engineering structural elements make use of adhesively bonded joints due to its lighter weight, load distribution and transmission mechanisms. The safety of the structure relies greatly on the condition of the adhesive joint. In this paper, the detection of debonding at the adhesive joint is investigated using a nonlinear Lamb wave mixing approach. The method relies on the presence of combined harmonics as indicative of material nonlinearity due to dislocations or anharmonicity in intact specimens or contact nonlinearity produced by the defects. In this study, experiments and three-dimensional finite element simulations were conducted and demonstrated that the presence of combined frequency wave due to contact acoustic nonlinearity is effective for indicating debonding. The effect of the debonding width was investigated and the debonding width was found to correlate well with the combined harmonic energy generated due to debonding. The findings presented in this study provides physical insights into the effect of debonding mechanisms at adhesive joints in related to the nonlinear Lamb wave mixing approach, and can be used to further develop the debonding detection techniques using wave mixing.
TL;DR: In this paper , the presence of combined frequency wave due to contact acoustic nonlinearity is used to detect debonding at the adhesive joint using a nonlinear Lamb wave mixing approach.
Abstract: Many engineering structural elements make use of adhesively bonded joints due to its lighter weight, load distribution and transmission mechanisms. The safety of the structure relies greatly on the condition of the adhesive joint. In this paper, the detection of debonding at the adhesive joint is investigated using a nonlinear Lamb wave mixing approach. The method relies on the presence of combined harmonics as indicative of material nonlinearity due to dislocations or anharmonicity in intact specimens or contact nonlinearity produced by the defects. In this study, experiments and three-dimensional finite element simulations were conducted and demonstrated that the presence of combined frequency wave due to contact acoustic nonlinearity is effective for indicating debonding. The effect of the debonding width was investigated and the debonding width was found to correlate well with the combined harmonic energy generated due to debonding. The findings presented in this study provides physical insights into the effect of debonding mechanisms at adhesive joints in related to the nonlinear Lamb wave mixing approach, and can be used to further develop the debonding detection techniques using wave mixing.
TL;DR: In this paper , an NDE method based on the Lamb wave propagation for the inspection of coated structures was developed and solved analytically, considering different thicknesses and a range of material properties decay for the substrate and coating.