基于局域共振声子晶体结构的低频振动能量回收研究

ENERGY HARVESTING BASED ON LOCALLY RESONANT PHONONIC CRYSTALS FOR LOW FREQUENCY VIBRATIONS

通过对局域共振型声子晶体的带隙机理及其对能量的局域化作用的分析,提出了一种用于回收环境低频振动能量的新型局域共振结构,并结合有限元方法对此新型结构的振动特性和能量回收能力进行了分析和研究.根据结构的共振模态和"质量-弹簧"系统简化模型,改变结构的材料和几何尺寸可以使结构的前7阶共振频率降到50-250Hz的低频范围.在此基础上发展了一种低频宽带多核结构,在250Hz以下拥有几十甚至更多的共振频率,最低频率低至20Hz,进一步优化了结构的低频宽带共振特性.利用有限元软件对有限结构的频率响应和压电特性进行分析,证实了新型局域共振结构的对环境中低频振动能量的回收能力,并满足了环境振动能量回收的宽带要求.该结构可以应用于各种便携式设备、无线传感器和微机电等自供电系统中,从低频振动环境中的获取能量为自身供电.

In this paper,a novel locally resonant structure with energy harvesting capabilities is pro- posed,based on the analysis of bandgap mechanisms and energy localization effect in locally resonant pho- nonic crystals. The vibration characteristics and energy harvesting capabilities of the structure are investi- gated using finite element methods （FEM）. According to the resonant modes and the simplified ＇mass- spring＇ system model,the first seven-order resonant frequencies of the structure can be reduced to the fre- quency range of 50-250 Hz by changing material and geometric parameters. With a developed multi-core structure,dozens,perhaps hundreds,of resonant frequencies appear in the frequency range below 250 Hz and the lowest frequency is 20 Hz. Based on the harmonic response analysis of finite structures, these low and broadband resonance properties as well as the piezoelectric energy harvesting capabilities are confirmed to satisfy the low and broadband frequency requirements of the energy harvesting from ambient vibrations. These structures will be helpful for the self-powered microsystems, such as portable electronic devices, wireless sensor,microelectromechanical systems （MEMS） and so on,to extract energy from ambient low frequency vibrations.