Study On Vibro-acoustic Characteristics Of Sandwich Structure With Visco-elastic Damping Material

Recently, lots of researches on the sandwich with rubber damping material were carriedout by scientists due to its superior mechanical performance and acoustical property, whichgained some valuable results from the theoretical, experimental research and numericalsimulation. Refer to related literatures, we can find that domestic research focused onstructural natural frequency and damping loss factor more than the sound transmission loss,and mostly not considered the variation characteristic of damping loss factor and elasticitymodulus of core material as the calculation frequency changes. Consequently, in order tosolving that problem, some works were done which had some guiding significance on theengineering practice that showed as follows:Computational formula of the structural natural frequency and damping loss factor wasdeduced by the Hoff theory of sandwich structure and damping energy dissipationmechanism. And then, the contrast between the analytical solution and simulation results ofnatural frequency contributed to the validity of the theoretical model. Similarly, thesimulation result of the damping loss factor was compared to the theoretical and simulationresults of previous literature. Finally, natural frequency and damping loss factor for differentstructure sizes of sandwich were analyzed in detail.Sound transmission loss of simply supported sandwich plate structure excited by thehybrid acoustical field was derived by the Hoff theory of sandwich structure, acousticalreflection and transmission mechanical. And stiffness theory model of sandwich structurehas different upper, lower steel plate thicknesses was analyzed in detail. Then, the soundtransmission loss of different structure sizes of sandwich was analyzed by the acousticfrequency characteristic curve of sheet structure. What’s more, influence of the variationcharacteristic of damping loss factor and elasticity modulus of core material as thecalculation frequency changes on the sound transmission loss was compared to thosedamping parameters had fixed values. Finally, the acoustic radiation characteristics ofsandwich was analyzed by the radiation impedance and mutual radiation impedance model,which considering the variation characteristic of damping loss factor and elasticity modulusof core material as the calculation frequency changes.Last but not the least, experimental research on the vibration damping characteristic ofthe hull base structure with visco-elastic composite damping material was carried out, thatvalidly proved the superior acoustical properties of sandwich structure, which found out themain transmission part of base power flow, gained the vibration damping effect as the constrain damping material pasted on different parts of the base, and explicitly illustratedthe vibration damping effect when the excitation point changed.Some new work was done in this paper, the mainly innovation points were that thesound transmission loss of simply supported sandwich plate structure excited by the hybridacoustical field was derived by the Hoff theory of sandwich structure, acoustical mechanicaland the stiffness theory model of sandwich structure has different upper, lower steel platethickness was analyzed in detail, which were used to emphasis analyze the soundtransmission loss and radiation sound power of sandwich has different upper, lower steelplate thicknesses. What’s more, experimental research on the vibration dampingcharacteristic of the hull base structure with visco-elastic composite damping material wascarried out, which gained the vibration damping effect as the constrain damping materialpasted on different parts of the base. This paper has some guidance on the acoustical designof ship structure.