Abstract：According to the mechanism of structure-borne sound radiation, the sound radiation power is related to the vibration velocity amplitude and distribution shape. Restraining the vibration and changing the distribution shape can reduce the sound radiation power. The covering layer can separate the structure and the fluid and change the vibration amplitude and the distribution shape. The chiral layer is composed of circular elements or nodes, connected by ligaments or ribs. The arrangement of nodes and ribs is such that chiral assemblies exhibit the ability of compatible deformation when nodes and ribs bend or twist. The chiral layer can change the high sound radiation efficiency shape in the surface of stiffened beam into the low sound radiation efficiency shape in the surface of covering layer and reduce the vibration amplitude of sound radiation surface. The stiffened beam is typical inhomogeneous component. The model is built to analyze vibration and the acoustic characteristics of stiffened beam with/without the chiral layer subject to force vibration using FEM/BEM and Rayleigh integration. The comparison between the stiffened beams with/without the chiral structure covering layer is carried out in terms of sound radiation efficiency, normal vibration speed and sound radiation power index. Results show that the sound radiation efficiency of covering surface is low than the stiffened plate surface. Harmonic results show that the chiral covering layer can’t effective control the vibration of stiffened plate and stop the vibration passing from stiffened plate to the acoustic radiation surface of chiral covering layer, but it can effective reduce the acoustic radiation power.
2014, Vol. 33 
