NETWORK ANALYSIS OF SCATTERING FROM AN INTERNALLY LOADED SPHERICAL-SHELL - RESONANCE IDENTIFICATION AND FREQUENCY-BY-FREQUENCY LIMITS ON THE SCATTERED FIELD
Pj. Titterton, NETWORK ANALYSIS OF SCATTERING FROM AN INTERNALLY LOADED SPHERICAL-SHELL - RESONANCE IDENTIFICATION AND FREQUENCY-BY-FREQUENCY LIMITS ON THE SCATTERED FIELD, The Journal of the Acoustical Society of America, 98(3), 1995, pp. 1667-1672
A generalized network model is used to interpret the scattering from a
submerged spherical shell with a two-spring/two-mass internal structu
re. In this model, generally available results are used for the fluid/
shell transmission paths, and lumped element methods are used for the
internal structure's admittance. This formulation emphasizes the field
quantities at the submerged-shell/intenal-structure interface. Of cou
rse, the network model has several forms; admittance, impedance, and n
etwork scattering are possible (among others). Impedance comparison at
the fluid/nominal-shell interface has been previously shown to determ
ine high-Q resonances in the scattered response associated with the lo
wer-branch spherical-harmonic modes. Admittance comparison at the subm
erged-shell/intenal-structure interface shows that the internal struct
ure shifts these lower-branch resonances and broadens their peaks. The
sawtooth pattern generated by these shifted and broadened resonances
distinguishes the form function with internal structure from the form
function without. Finally, network scattering variables and a power-fl
ow constraint are used to determine frequency-by-frequency bounds on t
he possible acoustic scattering for any passive internal point loading
. The scattering with the given lossless, two-spring/two-mass internal
structure oscillates between the maximum and minimum possible. (C) 19
95 Acoustical Society of America.