
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 drivepoint 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. Consistentlyderived 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 cutoff 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