水下纵肋加强圆柱壳低频振动与声辐射

采用模态叠加法建立了水下纵肋加强圆柱壳振动与声辐射计算模型,其中纵肋的建模采用了Timoshenko梁理论,且考虑了纵肋的径向弯曲、周向弯曲、轴向纵振动和扭转振动。与仅考虑纵肋径向弯曲振动的传统建模方法相比,文中计算结果与有限元解吻合更好。分析了光壳和纵肋加强圆柱壳的振动模态、壳面均方振速和辐射声功率,给出了纵肋对圆柱壳低频振动与声辐射的影响规律。结果表明,加入纵肋后圆柱壳产生了新的振动模态;在低频段某些频率附近,壳体振动有所增强,但高频振动被明显降低;加入纵肋后,圆柱壳在低频段辐射声功率会出现许多新的峰值,峰的数量随纵肋数目增加而逐渐减少,在更高频段上加入纵肋后辐射声功率明显降低。

Low-frequency vibration and sound radiation from submerged longitudinally stiffened cylindrical shell

The vibration and sound radiation analytical model of submerged longitudinally stiffened cylin-drical shell was developed.For the modeling of longitudinal stiffeners,Timoshenko beam theory was applied, furthermore, radial flexure, circumferential flexure, axial compression and torsion of longitudinal stiffeners were all considered. Compared with the traditional stiffener model considering the radial flexure only, the results of this paper show better agreements with the finite element method results. By analyzing vibra-tion modes, mean radial quadratic velocity and sound radiated power from cylindrical shell without and with longitudinal stiffeners, the effects of longitudinal stiffeners to low-frequency vibration and sound radi-ation of cylindrical shell were researched. The results show that many new vibration modes are made due to longitudinal stiffeners. Because of longitudinal stiffeners, vibration of shell is enhanced near some low fre-quencies, however, is suppressed in high frequency. In addition, longitudinal stiffeners induce many new sound radiated peaks for sound radiated power curve in low frequency, moreover, the number of peaks de-creases gradually with increasing the number of stiffeners. In higher frequency, the sound radiated power of cylindrical shell is reduced remarkably due to the longitudinal stiffeners.