Liu Fei, Horowitz Stephen, Nishida Toshikazu, Cattafesta Louis, Sheplak Mark
Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611-6250, USA.
J Acoust Soc Am. 2007 Jul;122(1):291-301. doi: 10.1121/1.2735116.
The development of a tunable, multiple degree of freedom (MDOF) electromechanical Helmholtz resonator (EMHR) is presented. An EMHR consists of an orifice, backing cavity, and a compliant piezoelectric composite diaphragm. Electromechanical tuning of the acoustic impedance is achieved via passive electrical networks shunted across the piezoceramic. For resistive and capacitive loads, the EMHR is a 2DOF system possessing one acoustic and one mechanical DOF. When inductive ladder networks are employed, multiple electrical DOF are added. The dynamics of the multi-energy domain system are modeled using lumped elements and are represented in an equivalent electrical circuit, which is used to analyze the tunable acoustic input impedance of the EMHR. The two-microphone method is used to measure the acoustic impedance of two EMHR designs with a variety of resistive, capacitive, and inductive shunts. For the first design, the data demonstrate that the tuning range of the second resonant frequency for an EMHR with non-inductive shunts is limited by short- and open-circuit conditions, while an inductive shunt results in a 3DOF system possessing an enhanced tuning range. The second design achieves stronger coupling between the Helmholtz resonator and the piezoelectric backplate, and both resonant frequencies can be tuned with different non-inductive loads.
本文介绍了一种可调谐的多自由度（MDOF）机电亥姆霍兹谐振器（EMHR）的开发。一个EMHR由一个孔口、背腔和一个柔顺的压电复合膜片组成。通过跨接在压电陶瓷上的无源电网络实现声阻抗的机电调谐。对于电阻性和电容性负载，EMHR是一个具有一个声学自由度和一个机械自由度的双自由度系统。当采用电感梯形网络时，会增加多个电自由度。使用集总元件对多能量域系统的动力学进行建模，并在等效电路中表示，该等效电路用于分析EMHR的可调谐声输入阻抗。采用双传声器法测量了两种带有各种电阻性、电容性和电感分流器的EMHR设计的声阻抗。对于第一种设计，数据表明，对于带有非电感分流器的EMHR，第二共振频率的调谐范围受到短路和开路条件的限制，而电感分流会导致一个具有增强调谐范围的三自由度系统。第二种设计实现了亥姆霍兹谐振器与压电背板之间更强的耦合，并且两个共振频率都可以通过不同的非电感负载进行调谐。
