Energy Flow Analysis Of Coupling Structures

Currently, how to reduce noise, vibration and harshness generated in engineering products has become a major priority in industry. As we all known, frequency range of audibility is from 20Hz to 20,000Hz.However, there is no single tool capable of providing appropriate method suitable for the entire audile frequency. Although, Energy flow analysis (EFA) and statistic energy analysis (SEA) have been proved as important tools for controlling vibrations of structures, statistic energy analysis (SEA) is only for high frequency analysis. The method adopted in this paper, Simplified EFEM (EFEM0), is derived by simplifying EFEM using Finite Volume Method, which combines the best features of EFEM and SEA.In the paper, differential equations for high frequency vibration are solved by EFEM0. During the analysis, vibration response of the basic ship structures under longitudinal wave and bending wave is determined in the frequency field. The researches carried out in this paper are only concerned high frequency vibration.Firstly three parameters, damping loss factor, coupling loss factor, and input power, are defined based on statistical energy analysis, then simplified formulas, which can be applied in EFEM0 are deduced in this paper. Parametric studies are also investigated.Secondly, the energy flow equations for one-dimension are derived from three-coupling beam model, and equations for two-dimension from orthotropic plate model.Thirdly, as examples, coupling beam, orthotropic plate and three-coupling plate are investigated respectively by assuming there are only longitudinal and bending waves exist in those structures., and the results show that EFEM0 is effective enough to predict vibration and noise in ship structures.Last, the computer programs of one-dimension and two-dimension system are developed based on both VISUAL FORTRAN and VISUAL BASIC, which make the method more convenient to apply to engineering practice.