Focusing of elastic waves by meta-structures is of considerable significance in energy harvesting. However, meeting both high transmission and wide bandwidth for these meta-structures is a challenge. In this paper, we propose a 3D-printed meta-slab with shuttle-like subunits with gradually varying thickness to focus incident flexural waves in broadband. Shuttle-like subunits have high transmission performance and frequency-dependent phase shifts. Based on these subunits, the meta-slab is designed by the mechanism of phase compensation, which makes the focal position unchanged with the incident frequencies. The wave fields of the transmitted region are obtained by the phased array theory and measured by the experiments. Their results are consistent and demonstrate well the focus ability of the meta-slab. Our design effectively concentrates the energy of broadband flexural waves, providing a new approach for energy harvesting.

通过元结构聚焦弹性波在能量收集中具有重要意义。然而，满足这些元结构的高传输和宽带宽是一个挑战。在本文中，我们提出了一种具有厚度逐渐变化的梭状亚基的 3D 打印元板，以在宽带中聚焦入射弯曲波。梭状子单元具有高传输性能和频率相关的相移。在这些子单元的基础上，通过相位补偿机制设计了元板，使焦点位置随入射频率保持不变。透射区的波场由相控阵理论得到，并通过实验测量得到。他们的结果是一致的，并且很好地证明了元板的聚焦能力。