Sluka Tomás, Kodama Hidekazu, Fukada Eiichi, Mokrý Pavel
Inst. of Mechatron. & Comput. Eng., Tech. Univ. of Liberec, Liberec.
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Aug;55(8):1859-66. doi: 10.1109/TUFFC.2008.869.
The design and realization of an adaptive sound-shielding system based on a method to control the effective elastic stiffness of piezoelectric materials are presented in this paper. In this system, the sound-shielding effect is achieved by a sound reflection from the piezoelectric curved membrane fixed in rigid frame and connected to an active analog circuit that behaves as a negative capacitor. The acoustic transmission loss through the curved membrane was measured for the incident sound of frequency 1.6 kHz and of acoustic pressure level 80 dB. When the negative capacitor in the system was properly adjusted, the acoustic pressure level of the transmitted sound was reduced from the initial 60 dB to 15 dB by the action of the negative capacitor. Then the system was exposed to naturally changing operational conditions, and their effect on sound-shielding efficiency was studied. It is shown that the acoustic transmission loss of the system dropped by 35 dB within 30 min from the moment of negative capacitor adjustment. Therefore, a self-adjustment of the system has been implemented by appending an additional digital control circuit to the negative capacitor. It is shown that the aforementioned deteriorating effect has been eliminated by the adjusting action of the control circuit. The long-time sustainable value of 60 dB in the acoustic transmission loss of the adaptive sound shielding system has been achieved.
本文介绍了一种基于控制压电材料有效弹性刚度方法的自适应隔音系统的设计与实现。在该系统中，隔音效果是通过固定在刚性框架中并连接到一个等效为负电容的有源模拟电路的压电弯曲膜的声音反射来实现的。针对频率为1.6kHz、声压级为80dB的入射声音，测量了通过弯曲膜的声传输损耗。当系统中的负电容得到适当调整时，通过负电容的作用，透射声的声压级从初始的60dB降低到了15dB。然后使系统处于自然变化的运行条件下，并研究了这些条件对隔音效率的影响。结果表明，从负电容调整时刻起，系统的声传输损耗在30分钟内下降了35dB。因此，通过在负电容上附加一个额外的数字控制电路，实现了系统的自调整。结果表明，通过控制电路的调节作用，消除了上述恶化效应。自适应隔音系统的声传输损耗实现了60dB的长期可持续值。
