Laboratory of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210093, People's Republic of China.
J Acoust Soc Am. 2011 Nov;130(5):2738-45. doi: 10.1121/1.3641365.
This study investigates the propagation of Lamb waves in phononic-crystal plates in the form of a sandwich-layered structure. The composite plates are composed of periodic layers bilaterally deposited on both sides of the homogeneous core layer. Using the analyses of the band structures and the transmission spectra, it is revealed that the core layer may induce significant modulations to the lower-order Lamb modes. The modulations are ascribed to the reshaped particle displacement fields of the eigenmodes. Prominently, the core layer made of soft material (rubber) combines the identical eigenmodes of the periodic layers into a pair of asymmetric and symmetric modes in which case the periodic layers vibrate independently. However, the core layer made of hard material (tungsten) or medium hardness material (silicon) couples the periodic layers tightly, in which case the composites vibrate as a whole. In addition, it is found that the phononic band gaps are very sensitive to the thickness of the core layer; this could be indispensable to practical applications such as bandgap tuning.
本研究探讨了在夹层结构形式的声子晶体板中兰姆波的传播。复合板由周期性层在同质芯层的两侧双侧沉积而成。通过对能带结构和透射谱的分析，揭示了芯层可能对低阶兰姆模产生显著的调制。这种调制归因于本征模的粒子位移场的重塑。突出的是，由软材料（橡胶）制成的芯层将周期性层的相同本征模组合成一对非对称和对称模态，在这种情况下周期性层独立振动。然而，由硬材料（钨）或中等硬度材料（硅）制成的芯层将周期性层紧密耦合，在这种情况下复合材料整体振动。此外，发现声子带隙对芯层的厚度非常敏感；这对于诸如带隙调谐之类的实际应用可能是必不可少的。
