SIMULTANEOUS MULTI-MODE AND DISPERSE ULTRASONIC GUIDED WAVES SIGNAL ANALYSING USING MORPHOLOGICAL COMPONENET ANALYSIS (MCA) METHOD

摘要

Ultrasonic guided waves were widely used in aeronautics, pipeline, vessels and so on because of its long distance propagation and large range detection property. Due to the long distance propagation along waveguides, the guided waves were not only possess the feature of ultrasonic bulk waves, but also dispersion and multi-mode characters, which limited detection effect of guided waves and increased the difficulty of feature recognition. Hence, dispersion suppression and multi-mode selection has been a research hotspot in international non-destructive testing field. It has great theoretical and realistic sense to research the dispersion and multi-mode for ultrasonic guided waves. In order to separate the different modes in guided waves signals, the morphology dictionary was constructed by different sub dictionaries, included gabor atoms, chirp atoms, wavelet atoms and discrete cosine atoms. The dictionaries proposed in this paper could be used to realize match pursuit decomposition and morphology decomposition and the morphology method could achieve more efficient results compared to match pursuit method. Furthermore, the separation of noisy by means of morphology method with discrete cosine atoms was presented and the rustles were satisfactory. The decomposition results were validated by simulation signals. The procedure inherited the advantages of sparse decompose method and could use different morphology dictionaries to decompose guided wave multi-mode signals effectively. The expansion of mode dictionaries will achieve accurate description for mode features, and could obtain capabilities to process complex multi modes signals, which reduced the complexity significantly in guided waves signals analysis.