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  • Wavelet transform of sound signal in fluid-filled viscoelastic pipes. DETC2001/VIB-21002
    Prek, Matjaž
    In viscoelastic pipes, where the material properties depends on a complex bulk modulus as well as on a complex shear modulus, the sound field within the fluid is affected. Therefore, the dispersion ... of flexural waves occurs in the pipe, while the speed of flexural waves decreases due to the coupled fluid mass. Coupling between the pipe wall and the fluid as decreases the sound speed in the fluid. Like-wise, the speed of sound in fluid is frequency-dependent, just as the group velocity of bending waves depends on the frequency. Wavelet transform of non-stationary sound signal was used to identify the frequency-dependent fluid sound speed. A time-frequency map, constructed by plotting the wavelet coefficient against the translation and scale parameters, shows an alteration in the low frequency waves. The so called "fluid mode" and "pipe mode" resonant frequencies are also clearly evident. Lastly, the impact of different pipe wall material properties is also shown. Wavelet analysis of the measured impulse response of a fluid-filled viscoelastic pipe provides useful tool for investigating its acoustical properties.
    Vir: 18th Biennial Conference on Mechanical Vibration and Noise (Vol. 6, part A, str. 7-13)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2001
    Jezik - angleški
    COBISS.SI-ID - 5217307

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