阻尼材料敷设方式对双层壳体声辐射性能的影响

研究了内、外壳体敷设粘弹性阻尼材料的有限长加肋双层圆柱壳的振动和声辐射性能,采用经典Flugge微分算子描述壳体的运动,运用Helmholtz波动方程和壳体表面的边界条件来求解位于内、外层壳之间的环形流场,并利用傅氏变换,可以求出声压的表达式,粘弹性阻尼层的运动用三维Navier方程描述,将阻尼沿厚度方向的位移用泰勒展开表示,利用不同的位移和应力的连续性边界条件分别建立了无阻尼以及三种阻尼材料敷设方式的振动方程,并用数值计算讨论了光壳和三种阻尼材料敷设方式对三种壳间连接形的双层壳体振动和声辐射的影响,结果表明敷设阻尼材料能降低壳体的辐射噪声,并且内壳敷设阻尼比外壳敷设阻尼的减振降噪效果好,内外壳均敷设阻尼材料的减振降噪效果最好。

Effect of viscoelastics layer cover type on characteristics of sound radiation from double cylindrical shell

The finite stiffened double cylindrical shell coated with viscoelastics layers on the inner and outer shell is systematically studied. The shell motion is obtained using the classical Flugge operator. The annular fluid field between the inner shell and outer shell is solved by applying Helmholtz equation and the continuity conditions of the displacement on the surface of fluid-structure, then the expression of sound pressure is obtained by Fourier transform. The layer motion is described by three-dimensional Navier equations. Displacement solutions of Navier's equations are expressed by using Taylor expansion along the layer thickness. The vibration equations of no layer and three cover types of layers are constituted using the different continuity conditions of displacement and stress. The effects of no layer and three cover types of layers on characteristics of sound radiation from three connection types of double cylindrical shells are discussed in numerical calculation. The results show that the layer can reduce the level of sound radiation greatly, and the effect of the double shell coated with viscoelastics layers on the inner shell is better than that of the double shell coated with viscoelastics layers on the outer shell, and the effect of the double shell coated with viscoelastics layers on the inner and outer shell on vibration decrease and noise reduction is the best.