The low-frequency sound absorption induced by localized resonances in phononic crystals shows promising applications for underwater materials. The finite element method is widely employed to calculate the underwater sound absorption characteristic, which is challenged when dealing with large scale computing model with high operational precision, however. The finite element method in this paper is improved according to the symmetry of the lattice and the scatterers in locally resonant structures; only an eighth of one unit cell needs to be considered to shorten the computing time. The calculation results of the improved method agree well with those of the original finite element method and the layer multiple scattering method. Using the simplified finite element method, the sound absorption of spherical, cylindrical and cubic scatterers is compared, and the shape effect of the scatterers on the sound absorption characteristics is investigated. The results show that low frequency sound absorption is closely related to the shapes of scatterers, and the absorption bandwidth can be improved by choosing optimal parameters.
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