用于变频噪声吸收的压电声学超材料

Piezoelectric Acoustic Metamaterials for the Absorption of Frequency-tunable Noises

提出基于压电声学超材料的吸声单元结构和电路,通过调节压电并联负阻抗电路实现吸声频率移动。吸声结构由质量块、压电层合板和刚性背板组成,压电并联电路包含负电容和负电阻电路。通过建立包含吸声结构声阻抗和电路阻抗的吸声系数分析模型,获得吸声频率与负电容的关系函数,并通过模型的稳定性分析确定吸声频率可调范围。单元样件的数值仿真和声管实验表明,负电容电路可将样件单元的吸声频率从1130 Hz移动到910 Hz,负电阻电路可以补偿吸声系数到0.9以上。仿真与实验结果在可调频率范围内基本一致。

A sound-absorbing unit based on the piezoelectric acoustic metamaterial is proposed,which can realize the tuning of the sound-absorbing frequencies in a narrow frequency band through the adjustment of the piezoelectric shunt negative impedance circuit.The structure of the piezoelectric metamaterial consists of a mass block,a piece of thin substrate plate laminated with a piezoelectric plate,and a backing plate.And the shunt circuit of the piezoelectric plate includes a negative capacitance circuit and a negative resistance circuit.The model of the absorption structure consisting of acoustic impedance and electric impedance is established for analyzing the absorption coefficient,and the relation function between the acoustic absorption frequency and the negative capacitance is obtained.Based on the stability analysis of the model,the tunable range of the absorption unit is determined.Simulation and experiments of a sample unit verify the frequency tunable characteristics and the sound absorption compensation.Simulation and experiment results show that the negative capacitance circuit can shift the central absorption frequency of the unit from 1130 Hz to 910 Hz,and the sound absorption coefficient can be compensated to over 0.9 by adjusting the negative resistance circuit.The simulation and experimental results are basically consistent each other in the tunable frequency range.