STP505

    Observation and Analysis of Simulated Ultrasonic Acoustic Emission Waves in Plates and Complex Structures

    Published: Jan 1972


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    Abstract

    Experiments have been performed with the Panametrics acoustic emission simulation test set which show that acoustic emission signals in plates and shells travel in the plate modes supported by these shapes. The first longitudinal plate mode has the highest group velocity in its low-frequency limit, and signals in that mode and frequency range arrive first, followed by strong signal at the velocity of the first flexural mode in its nondispersive region. In some cases the flexural signal is much stronger than the longitudinal signal. In general, the received signals are dispersed. The time-frequency-energy output matrix tends to be complicated, as energy of different frequencies is spread over time by the various dispersive modes. Special transducers can be used to discriminate against certain particle motions, suppressing the reception of certain modes, and may be useful in triangulation studies.

    Keywords:

    acoustics, emission, triangulation surveys, elastic waves, shear properties, piezoelectric transducers, dispersing, wave dispersion, plates (structural members), ultrasonic frequencies, Lamb waves, crack propagation


    Author Information:

    Fowler, KA
    Chief, Materials Evaluation Branch, and department head, Waltham, Mass.

    Papadakis, EP
    Chief, Materials Evaluation Branch, and department head, Waltham, Mass.


    Paper ID: STP35390S

    Committee/Subcommittee: E07.04

    DOI: 10.1520/STP35390S


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