具有长基座的双同心加筋圆柱壳振动和声辐射被动控制

Vibration of large cabin raft transmits into the submarine hull through the long frames. The elastic waves induced by the vibrational sources propagating in the frames are suppressed and the vibration of inner and outer submarine hulls is reduced, which are the fundamental measures to control the structural acoustic radiation from submarine hulls. It is very meaningful that study on acoustic radiation from stiffened double submarine hulls with long frames is helpful to design submarines with excellent acoustic performance. By using the Fourier transform and wave propagation method, vibrational and acoustic analytical model of stiffened double submarine hulls with long frames is established. Sound waves propagation between the inner shell and the outer shell, acoustic radiation characteristics of elastic waves in the frames, the helical wave spectra of the radial displacement for the inner and outer shells, the helical wave spectra of the far-field sound pressure for the double submarine hulls, sound power of the submarine hulls, vibrational power flow transfer of the point force in the frames in the axial direction of the submarine hulls are analyzed. In order to suppress the elastic wave propagation in the long frames, inner and outer submarine hulls, a method for passive damping layer treatment into the submarine hulls and the panels of the frames is proposed to perform vibrational and acoustic passive control of the stiffened double submarine hulls. Suppression functions of the passive damping layers on the vibrational and acoustic characteristics of submarine hulls are explored. By using the vibrational and acoustic experiment system of the stiffened double submarine hulls with long frames, control effectiveness of the passive constrained damping layers on the vibration of submarine hulls and acoustic radiation from submarine hulls is verified. Investigation fruits will provide the strong theory bases for the application of the method for passive vibration reduction and noise suppression to the vibroacoustic control of the power cabins of the double submarine hulls.

大型舱筏振动通过长基座向艇体传递，抑制振源激发的弹性波在基座中的传播和降低内外艇体的振动是控制艇体结构声辐射的根本措施。长基座加筋双层艇体声辐射研究有助于设计优良隐身性能的潜艇，具有重要意义。通过Fourier变换和波传播法，建立长基座加筋双层艇体振动和声辐射解析模型。分析双层艇体间声波的传播、基座中弹性波的声辐射特性、内外壳体径向位移螺旋波谱、双层艇体远场声压螺旋波谱、艇体声辐射功率、基座上点力作用下振动功率流沿艇体轴向传递规律。为抑制弹性波在基座和内外艇体中的传播，提出在艇体和基座面板上敷设被动阻尼层的方法被动控制加筋双层艇体的振动和声辐射，研究被动阻尼层对艇体振动和声辐射的抑制作用。通过长基座加筋双层艇体振动和声辐射实验系统，验证被动约束阻尼层对艇体振动和声辐射的控制效果。研究成果将为被动减振降噪方法应用于双层艇体动力机舱振动和噪声控制提供坚实的理论依据。

长基座是艇体内机械设备振动传递的重要路径，影响着艇体振动和声辐射特性。项目针对具有长基座的双同心壳体结构的振动和声学问题，研究这种结构的结构声学行为。在波数域上解析地建立了F型铺设约束阻尼层长基座和加筋双同心圆柱壳体的结构声模型，分析了这种粘弹性阻尼材料的减振降噪抑制效果。研究了声波在双壳体环形空间中的传播，内外壳体间的连接形式对内外壳体振动和表面声压的影响，F型基座与内壳体耦合振动特征，大阻尼粘弹性橡胶板的配方。实验测定了丁基橡胶板的弹性模量和剪切模量，制造了一个具有长基座双圆柱壳的潜艇动力舱段大尺度模型。在F型基座振动模型中，提出了两种解析模型，一种模型利用边界条件实现板的载荷传递，另一种模型采用外部载荷激起的扰动波在连接板间的反射与传播来分析。环形水介质中的声压以及内外壳体间的结构件如环形肋板、径向钢梁、纵向肋板产生的载荷传递是内外壳体动力耦合的两种主要形式。降低外壳体振动和声辐射的有效方法是在外壳体的外表面敷设粘弹性阻尼层和粘贴消声声衬。在中高频段，内壳体的表面声压功率谱的能量主要由内壳体的径向位移贡献，大量的声波可以从内壳体发射出来，没有太大衰减地透射过外壳，而且这种向外传播的声波主要是超声速波。在低频段，外壳体对内壳体发出的声波有遮挡效应，瞬态波被反射回来。当双层壳体周向具有双周期结构(径向支撑梁和纵肋板)时，发现了奇次波转换能降低壳体的刚度。内外壳体间采用纵肋板连接能降低壳体轴向辐射声压，这种辐射声压部分是由纵肋板的面内瞬态涨缩波产生的。在基座面板上敷设约束阻尼层，能降低基座传递给内壳体的载荷谱能量，能抑制基座和壳体的振动。但这种小面积铺设阻尼层，在某些频点反而使外壳体的辐射声压加大。通过模型测试，验证了在一些频段，基座上的约束阻尼层能降低基座和内外壳体的振动。长基座和加强筋使圆柱壳的周向不具有周期性，波的周向波数不应该限定为整数，而应该为复数，这为非均匀圆柱壳声辐射研究提出了新的问题。这些发现为基座艇体的振动和声学研究提供重要的理论参考价值。