Affiliations: State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, China
Correspondence:
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Corresponding author: Songling Huang, State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China. Tel./Fax: +86 10 62772131; E-mail:huangsling@tsinghua.edu.cn
Abstract: This work proposes an EMD-based STFT flight time
extraction method to recognize the different modes of overlapped Lamb wave
detecting signals (OLWDS) in aluminum plate due to its dispersion and
multi-modes property. Firstly, empirical mode decomposition (EMD) is
performed on the OLWDS and several intrinsic mode functions (IMFs) are
obtained, which turn out to be capable of clearly separating the OLWDS of
different modes. Secondly, the flight time is extracted from one of the IMFs
by implementing short-time Fourier transform (STFT) on the selected IMF, and
extracting the energy density distribution based on the center frequency
component of Lamb waves. The experimental platform for different modes of
OLWDS recognition in aluminum plate is established. The results show that
this method can extract more accurate flight time values compared with the
Hilbert-Huang transform (HHT) method and can accurately recognize the
overlapped Lamb waves of different modes.
