Aiming at facilitating Lamb wave signal analysis and mode characterization,an ultrasonic-Lamb wave niultimodal separation method combining short-time Fourier transform(STFT)and independent component analysis(ICA)was p...Aiming at facilitating Lamb wave signal analysis and mode characterization,an ultrasonic-Lamb wave niultimodal separation method combining short-time Fourier transform(STFT)and independent component analysis(ICA)was proposed.Temporal signals were projected into the time-frequency domain through STFT.Assuming that the energy trajectory of each Lamb mode is indepenclent in the time-frequency domain,ICA method was then applied to separate tlie superposed modes.The group velocity curve of each mode was extracted according to its time-frequency energy trajectory,based on which the plate thickness can be further estimated.The finite-difference time-domain(FDTD)simulated signals and experimental signals for a 1 nmi-thick steel plate were used to validate the performance of the proposed method.The three fundainental Lamb modes,A0,SO and A1 modes were separated.The average errors of group velocity estimation in the simulation and experiment were about 1.5%and 2.0%,with that of plate thickness estimation being 0.3%and 2.0%approximately.The simulated results indicate that,when the signal-to-noise ratio(SNR)is larger than 0 dB,the ICA method in the time-frequency domain can be used for ultrasonic Lamb wave multimodal separation,group velocity extraction and plate thickness estimation.展开更多
基金the National Natural Science Foundation of China(11974081,12004079)the International Cooperation Project of Shanghai Science and Technology Commission(17510710700)+3 种基金the Independent Project of State Key Laboratory of ASIC and System(2021GF002)the Program of Shanghai Academic Research Leader(19XD1400500)the Shanghai Rising Star Program(20QC1400200)the Natural Science Foundation of Shanghai(19ZR1402700).
文摘Aiming at facilitating Lamb wave signal analysis and mode characterization,an ultrasonic-Lamb wave niultimodal separation method combining short-time Fourier transform(STFT)and independent component analysis(ICA)was proposed.Temporal signals were projected into the time-frequency domain through STFT.Assuming that the energy trajectory of each Lamb mode is indepenclent in the time-frequency domain,ICA method was then applied to separate tlie superposed modes.The group velocity curve of each mode was extracted according to its time-frequency energy trajectory,based on which the plate thickness can be further estimated.The finite-difference time-domain(FDTD)simulated signals and experimental signals for a 1 nmi-thick steel plate were used to validate the performance of the proposed method.The three fundainental Lamb modes,A0,SO and A1 modes were separated.The average errors of group velocity estimation in the simulation and experiment were about 1.5%and 2.0%,with that of plate thickness estimation being 0.3%and 2.0%approximately.The simulated results indicate that,when the signal-to-noise ratio(SNR)is larger than 0 dB,the ICA method in the time-frequency domain can be used for ultrasonic Lamb wave multimodal separation,group velocity extraction and plate thickness estimation.
