复合兰姆波声子晶体中超宽部分禁带

兰姆波在声子晶体薄板中的传播特性因其在无损检测、 减振技术和传感器件等领域的潜在应用价值而受到越来越多的关注. 本文采用超原胞平面波展开法和有限元法系统地研究了复合对称结构声子晶体薄板中的兰姆波超宽部分禁带. 结果表明: 对于在薄板侧面对称地嵌入双层矩形空气柱构成的复杂系统, 低阶兰姆波部分带隙结构极为丰富. 将晶格常数(L)和板厚(H) 比值具有匹配关系的兰姆波声子晶体衔接构成复合结构, 低阶兰姆波部分禁带宽度因各组分结构的部分禁带交叠而得到显著拓宽, 可在低频超宽频带内实现对特定低阶兰姆波模式良好的模式选择功能. 该研究结果对兰姆波缺陷无损检测中模式优化选择及兰姆波单向导通器件设计等方面具有重要意义.

Large partial band-gaps for Lamb waves in multiple phononic crystals thin plates

During the past decade, a growing attention has been paid to the Lamb waves propagating in composite plates due to a variety of applications for nondestructive evaluation, vibration attenuation and Lamb wave sensors. We present a revised plane wave expansion method and a finite element method to study the large partial band-gaps of a multiple Lamb wave phononic crystal thin plate with a symmetric mirror plane The results show that lots of partial stopbands of lower-order Lamb waves exist and can be substantially enlarged by using multiple heterostructures which consist of several pieces of phononic crystal with different ratios of the thickness (H) to the lattice period (L). These contribute to good mode choice for lower-order Lamb waves, which is believed to have much significance for optimially choosing models in Lamb wave nondestructive test and the one-way Lamb wave mode transmission.