THE LOW-FREQUENCY VIBRATION OF A RIBBED CYLINDER .2. OBSERVATIONS AND INTERPRETATION

The vibratory behaviour of ribbed cylinders is discussed. Very good agreement has been obtained between theoretical modelling described elsewhere and measurements on a ribbed cylinder over a frequency range from zero to about three times the ring frequency. The first three pass bands for vibration transmission along the cylinder occur in this frequency range, associated with the first two resonant modes of a single bay of the structure and with a cross-sectional resonance of the T-section ribs. The position and nature of these three bands as a function of circumferential wavenumber are studied. Also the group velocity as a function of frequency and wavenumber is studied, and agrees in considerable detail with that obtained from measured sonograms.