Acoustic scattering from submerged elastic objects
Publish date: 2002-01-01
Report number: FOI-R--0307--SE
Written in: English
Numerical studies of hydroacoustic scattering from submerged 3D elastic bodies have been performed. The underlying applications are identification of objects buried in the seabed and design of embedding polymer bodies for fiber-optic hydrophones. The first study concerns data from a sea trial for scattering from a buried concrete-filled tyre. We extend a previously reported analysis of the trial by using more realistic models of the tyre and the seabed. In the second study, we investigate the elastic wavefield inside a circular polymer disc immersed in water and excited by an incident plane wave. We compute the normal stress field inside the disc and the unit elongation of the polymer material along circular curves in the equatorial plane of the disc for some choices of polymer material. For the buried tyre, the results provide an improved understanding of the trial data. The analysis indicates that the effects of seafloor roughness and sediment inhomogeneities on the data are smaller than previously believed, and that the tyre material is stiffer than homogeneous concrete, probably due to reinforcing steel bars. For the polymer disc, the results yield estimates of the sensitivity and bandwidth of hydrophones of the specified shape and material type.