次级源为平面声源的三层有源隔声结构,系统易于实现且具有良好的低频隔声性能。误差信号的检测是实现该系统的关键问题。将分布式位移传感材料聚偏氟乙烯(Polyvinlidenefluoride,PVDF)薄膜敷设于系统外层辐射板来检测结构辐射模态幅值而实现误差传感。用声.振耦合理论对振动系统建模,选取合适的控制策略和目标函数,并推导检测辐射模态幅值的PVDF形状设计公式。根据控制前三层结构中声能量的带通传输规律,选取合适的控制目标作为误差信号,并对各阶辐射模态传感器形状进行分频段设计。结果表明,由于三层结构特殊的能量传输规律,以辐射板前三阶辐射模态为控制目标即可获得理想的降噪效果。结合能量传输的带通特性,设计的各阶辐射模态幅值PVDF传感器只检测其声辐射占主导的频段内的辐射信息,保证传感精度的同时有效简化了PVDF形状。
The active triple-panel sound insulation structure with planar secondary source can be easily implemented and has better low frequency sound insulation performance. Error sensing strategy is one of the key problems encountered in the implementation of such a system. The error sensing strategy is implemented by laying the distributed displacement sensor, i.e., tailored polyvinlidene fluoride (PVDF) which can sense structural radiation modes, on outer radiated panel. The theoretical model is established by using vibro-acoustic coupling approach. And the appropriate control strategy and objective function are chosen. The design formulation for the shape of PVDF used for sensing the radiation modes is also derived. Subsequently, based on the rule of sound energy transmission through triple-panel system, the appropriate objective function for the triple-panel system is chosen. And the shape of PVDF sensor is designed in different frequency range for different radiation modes. Results obtained demonstrate that, due to the special sound energy transmission rule in the triple-panel system, only using the first three order radiation modes of the radiated panel as control objective can achieve prefect noise reduction. The design of the PVDF sensors with special shape needs to be accomplished only in their respective dominant frequency bands for the first three order radiation modes. As well as improving sensing precision, this can simplify the shape of PVDF.