Ship Structure Sound Press Contribution Analysis And Optimization Method Based On ATV Technology

With the maturity and widespread use of low frequency sound water detection technique, the mechanical noise severely impacts the performance of the surface ship radiation noise and the interior noise stealth design, which becomes a highlighted issue that should be imminently solved. Ship structure, electromechanical equipment and external two-phase flow environment form a large, complex and flexible vibration acoustic coupling dynamic system. Driven by the electromechanical equipment, the structure of the running ship generates and transfers vibration energy, which spreads to the whole structure and forms plate bending vibration and radiate acoustic wave underwater through fluid-structure coupling movement on wet surface(underwater acoustic radiation S face). Therefore, it is an important solution to reduce the underwater acoustic radiation effectively and improve the performance of the noise stealth, which needs a new idea to study the structure-borne vibration noise behavior, systematically analyze vibration noise-induced mechanism and develop optimization process.Based on the steady, certainty and linear hypothesis, and the idea of using “force, vibration, sound” three-terminal physical quantity separation, the vibration noise mechanism is quantitatively analyzed, the three-structure natural mode parameter, mode participation factor, vibration transfer function, acoustic transfer vector(ATV) and three sound pressure contribution are reviewed systematically to study the mathematical property and physical foundation. The relations and technical integration characteristics among such concepts are discussed. The newly developed frequency domain linear technology of structure vibration noise is summarized and raised. The accuracy, reliability, scope of application and precautions of frequency domain linear technology and vibration noise characteristics of the stiffened plate are studied through the design of synchronous vibration noise test in 122-channel semi-anechoic room, while typical surface ship cabin is taken as the object for development and validation of new optimization design process.From the main discovery of this thesis, the radiation noise vibration transfer function and ATV are the two main cores to deal with the structure frequency domain problem. The complete and accurate acoustic radiating surface vibration transfer function needs mixture test and new development of simulation technology, and the right simulation precision ATV can reach 0.5 d B; ATV is easy with interpolation and storage, and can develop modal acoustic transfer vector technology combining with structural modal; mathematical physics properties of ATV makes the new path optimization design technology up to two days from the traditional months iteration calculation. Based on the ATV and acoustic radiating surface vibration result, the calculation formula of rapid sound press contribution and the concept of normalized sound press contribution are also proposed.In addition, the conclusions, such as the phenomenon of limited structure’s free edge main contribution, the incentive location’s big impact on sound response, deserve attention during the design; the regional stiffness optimization of main contribution can effectively control the sound pressure response, and control results have spectrum robustness.