Accession Number : AD0646352

Title :   POINT IMPEDANCE OF LONG CYLINDRICAL SHELLS.

Descriptive Note : Final rept.,

Corporate Author : CAMBRIDGE ACOUSTICAL ASSOCIATES INC MASS

Personal Author(s) : Fraser,W. B. ; Geers,T. L. ; Hadden,W. J. ; Feit,D.

Report Date : DEC 1966

Pagination or Media Count : 28

Abstract : A procedure is presented for computing the mechanical drive-point impedance of cylindrical shells of effectively infinite length (i.e., no significant reflections from shell extremeties). The impedance of a uniform isotropic infinite cylindrical shell is obtained as the reciprocal of a sum of modal mobilities. Consistently-derived approximate expressions are given for the ranges of frequency and mode number in which simplifying assumptions may be made. It is shown explicitly that the sum of modal mobilities converges to a finite value, except at certain resonant frequencies. Each resonance coincides with the cut-off frequency of a lobar mode below which this mode does not contribute to energy spreading axially from the point of excitation. The significance of these resonances is explored by examining the transient response of a membrane waveguide when it is abruptly excited at one of its resonant frequencies. (Author)

Descriptors :   (*SHELLS(STRUCTURAL FORMS), MECHANICAL IMPEDANCE), CYLINDRICAL BODIES, SUBMARINE HULLS, RESONANCE, VIBRATION

Subject Categories : Submarine Engineering
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE