Study On The Sound Insulation And Vibration Characteristics Of Sheet-beam Structure Based On The Hybrid FE-SEA Method

Sheet-beam structure, as its good bearing capacity, shock impact resistance and vibration-isolating performance, has been widely used as warship hull and its inner supporting structure at present, and a lot of studies on its vibro-acoustic characteristics have been carried out by domestic and overseas scholars. From the numerical computational viewpoint, taking the hybrid FE-SEA method based on wave approach as computational basis, the sound insulation and vibration characteristics of sheet-beam structure with different type combining form were researched systematically. At the same time, in order to demonstrate the correctness of numerical calculation, theoretical analysis and experimental measurement were also applied as the necessary methods in this paper.Firstly, the established processes of statistical energy analysis (SEA) and the hybrid FE-SEA method based on wave approach were introduced in detail. And SEA takes intersystem power flow balance equations as its key theory. The identification of statistical subsystems and its application frequency partition principle, fundamental assumptions, calculation methods of relative parameters were also introduced. In addition, the sound insulations through single and double glazing windows were analyzed as one numerical example. Via compared with measured data, the validity of modeling was demonstrated.However, the diffuse field reciprocity relation plays a vital role in establishing the hybrid FE-SEA method based on wave approach, which establishes the energy relationship between deterministic subsystems and statistical subsystems. On this basis, the statistical subsystems was considered receiving power input arising from outside excitation, rather than considering the power flow from this statistical subsystem to other statistical subsystem not coupled with the same deterministic subsystem, which avoids partitioning SEA and hybrid method unclearly in the past, and makes the new power balance relation become conform to the real situation. Besides, the power balance schematic diagram of statistical subsystem and computation flow charts of hybrid FE-SEA method were also modified properly in this paper.Secondly, the sound insulations of single and double plate structure without stiffeners, the sound insulations and vibration response of single and double sheet-beam structures were studied based on hybrid FE-SEA method. Besides, the influence on the sheet-beam structural sound insulation and vibration of the spacing, moment of inertia and boundary constrain condition of stiffeners, which also includes whether in orthogonal or one-way, whether single or double were also researched in this paper. With regard to large mass stiffeners, also called blocking mass, the vibration-isolating performance of approximate equal-mass hollow beam and solid blocking mass was analyzed based on wave approach, and the effects of thickness and length on the transmission loss of hollow blocking mass were also discussed in this paper. In order to demonstrate the validity of theoretical analysis, on one hand, the vibration-isolating performance of blocking masses was numerical calculated by hybrid FE-SEA method. On the other hand, the model experiment of sheet structural with approximate equal-mass hollow beam and solid beam was designed. Through comparing the predicted results and measured data of sheet-beam structural vibration velocity, the validity of analyzing vibration-isolating performance with hybrid FE-SEA method modeling was verified.Lastly, one underwater double stiffened cylindrical shell with both ends simply supported was modeled in this paper. Through establishing the numerical model based on FEM/BEM method, the influences on radiation acoustic power, the vibration velocity and radiation efficiency of out shell, the sound pressure in cabin, and the platform velocity of the thickness, spacing of ribbed plates between double shells were also studied.Through the research work in this paper, the SEA and hybrid FE-SEA methods based on wave approach were comprehended more deeply, and the law of influence on the sheet-beam structural sound insulation and vibration characteristics of relative parameters was revealed, which might provide one certain reference value for analyzing complex structural vibro-acoustic problem based on hybrid FE-SEA method.