Diffraction of a plane wave in air by a cylindrical shell with two local masses

The diffraction of a plane wave by a cylindrical shell with two inertial masses attached symmetrically (at = ±₁) to its surface is investigated. The frequency response characteristics of the scattered field are calculated for a shell equipped with diametrically opposite masses (₁ = /2) and driven only by symmetric (about the plane =0, =) modes of vibration. It is established that the level of the scattered field in the interval of frequencies corresponding to even symmetric mode orders increases upon transition from the model with a single local mass (at =) to the model with two masses (at =±/2) (i.e., with a split inhomogeneity). At the frequencies of odd modes the scattered field coincides with the field of the homogeneous shell. The directivity patterns of the scattered field of a shell with two masses (at =±/2) are determined.Architecture and Construction Institute, Nizhegorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 3, pp. 289–299, March, 1994.