We study the formation of frequency band gaps in single column woodpile phononic crystals composed of orthogonally stacked slender cylinders. We focus on investigating the effect of the cylinders local vibrations on the dispersion of elastic waves along the stacking direction of the woodpile phononic crystals. We experimentally verify that their frequency band structures depend significantly on the bending resonant behavior of unit cells. We propose a simple theoretical model based on a discrete element method to associate the behavior of locally resonant cylindrical rods with the band gap formation mechanism in woodpile phononic crystals. The findings in this work imply that we can achieve versatile control of frequency band structures in phononic crystals by using woodpile architectures. The woodpile phononic crystals can form a new type of vibration filtering devices that offer an enhanced degree of freedom in manipulating stress wave propagation.
在声子学领域，周期性模式控制振动，从而控制物质中的热和声音的流动。在这种声子晶体中产生的带隙实现了低耗散振动模式，并实现了对机械量子比特、高效波导和最先进传感的应用。在这里，我们结合声子和二维材料，并探讨通过施加机械压力操纵声子晶体的可能性。为此，我们制造了最薄的声子晶体从单层石墨烯和模拟其振动特性。我们发现一个带隙的MHz制度，在此范围内，我们本地化的缺陷模式与一个小的有效质量为0.72 ag = 0.002 $m_{physical}$。最后，我们利用石墨烯的灵活性和机械调谐有限大小的声子晶体。在高达30千帕的静电压力下，我们观察到整个声子系统的频率上升超过350%。同时，缺陷模式保持在带隙内并保持局部化，这表明高质量、动态可调的机械系统。
Tailoring of phononic band structures in colloidal crystals
本文报道了二维胶体晶体在光致基底势作用下的弹性性质的实验研究。与最近的理论预测一致[H. H. vonGruenberg和J.Baumgartl，Phys.Rev.E75，051406（2007）]，这种系统的声子能带结构可以根据衬底势的对称性和深度来调谐。二元晶体的计算表明，声子带工程也可以通过对电位的变化进行，从而打开了新的视角，为制造声子晶体的带隙可调的外部领域。
