摘要
基于结构声辐射机理可知,在低频区域结构的声辐射功率和声辐射表面的振速幅值和分布形状(声辐射效率)相关,抑制振动和改变振速分布可以降低结构的声辐射功率。在结构表面敷设一层覆盖层用来隔开结构和流体区域,可以降低声辐射面的振动和改变振速分布。手性结构覆盖层由中心圆柱和四周韧带连接而成,具有协调变形机制,当手性结构中圆柱和韧带发生弯曲变形时,可以将不均匀结构高声辐射效率的振速分布形状转变为覆盖层表面低声辐射效率的振速分布形状并且覆盖层表面的法向振动幅值小于不均匀结构表面的法向振动幅值,实现不均匀结构声辐射抑制。加筋结构是不均匀结构,使用加筋梁模型可以反映出不均匀结构的声辐射机理。建立敷设和不敷设手性覆盖层加筋梁结构的二维有限元/边界元模型,利用Raleigh积分公式研究了其振动特性和声辐射特性。通过对比敷设和不敷设手性覆盖层加筋梁模型的声辐射面,声辐射效率、法向均方根振速和声辐射功率,分析了手性覆盖层对加筋梁声辐射的抑制机理。计算结果表明:加筋梁敷设覆盖层后,声辐射面由加筋板梁表面为覆盖层表面;覆盖层声辐射面的声辐射效率低于加筋板表面的声辐射效率。谐响应分析表明:手性覆盖层不能有效的抑制加筋梁的振动但是可以有效的抑制加筋梁传递到覆盖层声辐射面的振动,并且对加筋梁的声功率辐射有较好的抑制作用。
According to the mechanism of structure-borne sound radiation,structural sound radiation power is related to vibration velocity amplitude and distribution shape of a sound radiation surface.Suppressing vibration and changing distribution shape of vibration velocity can reduce the sound radiation power of a structure.A covering layer can be used to separate a structure and fluid field and to change vibration velocity amplitude and its distribution shape of sound radiation surface of the structure.The chiral covering layer is composed of circular elements or nodes connected with ligaments or ribs.The arrangement of nodes and ribs is such that chiral assemblies exhibit the ability of coordinating deformations when nodes and ribs bend or twist.The chiral layer can change the vibration velocity distribution shape corresponding to the higher sound radiation efficiency on the surface of a stiffened beam into that corresponding to the lower sound radiation efficiency on the surface of the covering layer and reduce the vibration velocity amplitude of the sound radiation surface.A stiffened beam is a typical inhomogeneous component.Here,its model was built to analyze vibration and acoustic radiation characteristics of a stiffened beam with/without a chiral layer subjected to forced vibration using FEM/BEM and Rayleigh integration.The comparison between the sound radiation efficiency,normal vibration speed and sound radiation power of stiffened beams with/without the chiral covering layer was performed.Results showed that the sound radiation efficiency of the covering layer surface is lower than that of the stiffened beam surface.Harmonic response analysis showed that the chiral covering layer can＇t effectively suppress the vibration of the stiffened beam but can effectively suppress the vibration transferred from the stiffened beam to the acoustic radiation surface of the chiral covering layer,and can effectively reduce the acoustic radiation power of the stiffened beam.
出处
《振动与冲击》
EI
CSCD
北大核心
2014年第11期178-183,共6页
Journal of Vibration and Shock
基金
自然科学基金(11172173)
关键词
手性覆盖层
不均匀结构
加筋梁
声辐射
chiral covering layer
inhomogeneous structure
stiffened beam
sound radiation
