基于二维声子晶体的大尺寸夹心式换能器的优化设计

夹心式换能器应用极为广泛,但当其横向尺寸过大时,存在耦合振动,影响其辐射面的位移分布.本文通过在大尺寸夹心式换能器的前盖板中加工周期排列的槽,来形成一种二维声子晶体结构.随后,采用有限元法对基于二维声子晶体的大尺寸夹心式换能器的振动传输特性、共振频率以及发射电压响应进行仿真模拟,讨论了开槽高度和开槽宽度对其带隙、共振与反共振频率、带宽以及辐射面位移分布的影响.研究结果表明,通过在大尺寸夹心式换能器中应用声子晶体结构可对其进行优化设计.当大尺寸夹心式换能器的工作频率位于其带隙范围内时,二维声子晶体结构能有效地抑制其横向振动,从而改善换能器辐射面位移分布的均匀程度.此外,在大尺寸夹心式换能器的前盖板中加工二维声子晶体结构,能有效提升换能器的带宽,进而拓宽大尺寸夹心式换能器的工作频带.

Optimal design of large-sized sandwich transducer based on two-dimensional phononic crystal

Sandwich transducers are extremely versatile, but when the lateral dimension is too large, the displacement of the radiating surface is uneven due to the coupling vibration. Due to the unique vibrational band gap characteristics of phononic crystal, vibrations in the bandgap range can be prohibited from propagating for infinite periodic structure or suppressed for finite periodic structure, which makes it widely used in the field of vibration suppression. In this paper, a two-dimensional phononic crystal structure is formed by processing periodically aligned grooves in the front cover of a large-sized sandwich transducer. Since the periodic grooves are formed in the radial direction, the radial waves cannot propagate, and thus the lateral vibration is suppressed. Subsequently, the finite element method is used to simulate the vibration transmission characteristic, resonance frequency and emission voltage response of a large-sized sandwich transducer based on two-dimensional phononic crystal. The effects of slot height and slot width on its bandgap, resonance and anti-resonant frequency, bandwidth, and displacement profile of the radiating surface are discussed. The results show that the phonon crystal structure can be optimized by using a large-sized sandwich transducer. The large-sized sandwich transducer based on two-dimensional phononic crystal has a lateral band gap. When the operating frequency of the large-sized sandwich transducer is within the band gap range, the two-dimensional phononic crystal structure can effectively suppress the lateral vibration, and the uniformity of the displacement distribution of the radiating surface of the transducer is improved. In addition, when the slot width is constant, the bandwidth of the large-sized sandwich transducer based on the two-dimensional phononic crystal increases as the slot height increases. Similarly, when the slot height is constant, the bandwidth of the large-sized sandwich transducer based on the two-dimensional phononic crystal increases as the slot width increases. The two-dimensional phononic crystal structure is processed in the front cover of the large-sized sandwich transducer, and the working frequency band of the large-sized sandwich transducer is effectively broadened.