Pd. Thorne et al., MEASUREMENTS AND ANALYSIS OF ACOUSTIC BACKSCATTERING BY ELASTIC CUBESAND IRREGULAR POLYHEDRA, The Journal of the Acoustical Society of America, 102(5), 1997, pp. 2705-2713
Underwater acoustic studies of backscattering by submerged targets hav
e generally focused on bodies with spherical and cylindrical symmetry,
However, there are interests in scattering by objects which may be ch
aracterized by more angular features, with surfaces that tend to be co
mposed of facets and edges, To investigate the scattering properties o
f such bodies, the backscattering by a number of elastic cubes, and ir
regularly shaped polyhedra, have been studied. Data were collected by
measuring the band limited impulse response of the scatterers, using a
broadband transducer, which operated as a transceiver, both transmitt
ing and receiving signals. To present the scattering measurements nond
imensionally a form function definition has been employed to normalize
the backscattered signals. The normalized frequency has been expresse
d as ka, where k is the acoustic wave number, and a is a characteristi
c dimension of the scatterer. The cube observations covered a broad ka
range, ka = 3-34, thereby encompassing the lower ka scattering region
where the cube can be considered to be nominally rigid, through to hi
gher ka values where it would be expected that the elastic properties
of the cube become important. The measurements on irregular polyhedra
are more limited in extent, however, the results are presented for com
parison with the cube data. To compare the observations with predictio
ns, computations of acoustic backscattering for both rigid and elastic
cubes are presented. (C) 1997 Acoustical Society of America.