Abstract: To control the low frequency vibration and noise line spectrums of a ships floating raft under power mechanical excitation, the coupled vibration equations of power machinery-plate-local resonance units were established by the variational principle, and the solution of the coupled vibration equation was derived by the modal superposition method. Then the calculation formula of the radiated sound power level of the plate was given. A small size and lightweight low frequency resonator was designed, and the effects of the locally resonant unit on the control of low frequency vibration and radiation sound power line spectrum of the plate structure were investigated under the excitation of power machinery. The results show that, with the additional mass less than 3% of the plate mass, the average surface velocity level and the radiated sound power level of the plate structures under low frequency vibration line spectrum may be reduced by more than 10%; when the locally resonant unit contains multiple resonators with different intrinsic frequencies, multiple low frequency vibrations line spectrum of the plate structures may be controlled. 

Key words: ship floating raft, low frequency vibration line spectrum, locally resonant, average surface vibration speed, radiation sound power

摘要： 为控制动力机械激励下的舰船浮筏低频振动和噪声线谱，由变分原理建立了动力机械平板局域共振单元的耦合振动方程，采用模态叠加法导出了耦合振动方程的解，并给出了平板辐射声功率级的计算公式；设计了小尺寸轻质低频局域振子，分析了局域共振单元对动力机械激励下平板结构低频振动与辐射声功率线谱的控制效果。研究表明：在附加质量小于平板质量3%的要求下，局域共振单元可将低频振动线谱激励下平板结构表面平均振速级和辐射声功率级降低10%以上；当局域共振单元中包含多个固有频率不同的局域振子时，可以控制平板结构的多个低频振动与噪声线谱。

关键词: 舰船浮筏, 低频振动线谱, 局域共振, 表面平均振速, 辐射声功率