Abstract: A medium with periodic heterogeneity has special frequency ranges in which waves may be either effectively attenuated or allowed to propagate in space. These frequency ranges are referred to as stop bands (or band gaps) and pass bands (or bands). Such unique characteristics can be employed to design a kind of virtual mechanical filters with periodic structures. The mechanical filter can be inserted between the lower isolator and the base of the raft isolation system to alter the transmission properties from the machine to the base, so that the frequency of the raft isolation system can approach its excitation frequency, and differ from the shells intrinsic frequency and excitation frequency of the cabin. The transmission matrix method is used to analyze the transmission property and the dynamic response of the raft system. Result shows that the responses of displacement, force and power flow of the base can be greatly reduced when the excitation frequency is within the stop bend of the periodic structure.

Key words: vibration and wave, periodic structure, stop bands, transmission matrix method, impedance mismatch

摘要： 弹性波在周期性结构中传播时会形成特殊的阻带和通带结构。当弹性波的频率处于阻带范围内时，弹性波及振动是不允许传播的。根据这一性质，设计一种虚拟的周期结构机械滤波器，用于浮筏隔振系统中的下层隔振器和基座间，通过改变从机组到基座之间的传递特性，使浮筏隔振系统中与激励频率相近、并和舱段壳体振动相关的固有频率和激励频率错开。利用传递矩阵法研究浮筏隔振系统下层隔振器和基座间插入周期结构机械滤波器后的传递特性和动态响应，通过研究表明：当激励频率在周期结构的阻带之内时，基座的位移响应，力响应和功率流响应将大大减小。

关键词: 振动与波, 周期结构, 带隙结构, 传递矩阵法, 阻抗失配