Research The Vibration Transmission Characteristic Of Foundation Based On FEM Power Flow

Mechanical noise is the main noise source of hull at low speed, which directlyinfluences the safety and operational capability of submarine. Foundation is the main loadbearing body of hull power equipment, which is directly connected with the hull structureand the main ways to transfer the mechanical vibration. Therefore, through the research onvibration transfer characteristics of foundation, reducing vibrational energy from thefoundation to the hull, and thus reducing the hull outward radiation noise, is important toengineering applications. The paper does some basic research on the vibration transfercharacteristics of foundation, using the theory of finite power flow.Firstly, compare various vibration transmission evaluations, and put forward thevibration evaluation indicators: power flow transmissibility, in the paper. Give the theoryand formula about the finite power flow, do calculation and analysis on the simple model,L-shaped plate, compare the result to the existing analytical results of mobility power flowmethod. Validate the feasibility and correctness of method in the paper, which can beapplied to the analysis of complex structure.Secondly, based on natural vibration and harmonic response analysis of approximatereal proportion of hull cabin model, consider the hull structure and the fluid load effect onthe foundation vibration transmission, and reach some useful conclusion.In order to analyze vibration transmission mechanism of foundation, the foundationis independent from the complex structure model. The first-order natural frequencyestimation formulas about foundation board, web and a panel are given in the paper. Thennature vibration information of foundation can be obtained quickly in engineering practice.Through the analysis of vibration energy transmission in foundation structure, obtain themain pathways as well as the dominant role of wave forms of foundation vibrationtransmission. In the practical engineering, the design goal of foundation is "high input impedanceand transmission loss". Finally, the paper describes the commonly methods in foundationstructural acoustic design. Meanwhile, the measures, lying of constrained damping layerand opening the hole, are used in simple foundation model. Calculate and analyze theeffect on the vibration transmission of foundation. Provide some references for practicalengineering application.