The use of turbofan engines of high bypass ratio has caused the low-frequency structure-borne noise. To investigate the medium and low frequency vibration transmission through wing structure to airframe, we introduce the double-beam dynamic model of a wing and build the "pylon-wing-airframe" dynamic half model of a full airplane, which takes into account the dynamics of an actual airplane. Sections 1 through 4 of the full paper explain the exploration mentioned in the title; their core consists of; ( 1) we use the vibration spectrum of the turbofan engines to calculate the vibration load of the airplane at each section of the airframe transmitted from wing to the air-frame , which provides the input data for estimating the noise level of the pressurized cabin; (2) through simulation , we identify the main path of engines' vibration transmission to the airframe; the simulation results, given in Figs. 6 and 7, and their analysis form, in our opinion, a useful preparation for pylon structure vibration reduction, engine vibration isolation mounting and the acoustic design inside the cabin.%高涵道比涡扇发动机的振动冲击频段向低频转移,使得飞机舱内噪声频率分布中的低频结构传递噪声变得更加突出.为了研究发动机振动载荷通过机翼向机身传递的中低频振动特性,文章针对真实客机的结构动力特性,创新地提出了机翼双梁动力学模型概念,建立了“吊架-机翼-机身”全机动力学有限元模型；基于发动机的振动载荷谱,分析了发动机振动通过机翼向机身结构传递的载荷特性,为后续舱内噪声预计提供了数据输入；并仿真辨识了发动机振动传递的主路径,为舱内声学设计及发动机隔振安装提供了基础数据.文中研究结果对我国大型客机的减振降噪设计工作有重要的工程参考价值.
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