In this paper, we use shape memory alloy springs, electromagnets, ordinary springs and two metal beams to construct a double-layer phononic crystal beam. The electromagnets can be controlled to be in contact or separated by means of temperature and electric current. Firstly, we use transfer matrix method to derive the theorical solutions of the bandgap properties, and compare them with finite element results. Then, we focus on the influences of different parameters on bandgap properties to see how they can be effectively regulated. Finally, we take account of the symmetry of the structure and excitations for simplification and get two basic solutions, based on which the bandgap characteristics for an arbitrary excitation are obtained via superposition. It is shown that temperature and electric current can change the bandgap characteristics effectively, and while both the lattice constant and SMA spring stiffness have a global and huge influence, the ordinary spring stiffness and magnetic force all exhibit a local and detailed modification to the bandgaps. When the metastructured beam is perfectly symmetric but subjected to an antisymmetric excitation, we can obtain an extremely low and wide bandgap. The structure designed here is expected to play a role in actively controlled low-frequency noise reduction.

在本文中，我们使用形状记忆合金弹簧，电磁体，普通弹簧和两个金属梁来构造双层声子晶体束。可以通过温度和电流控制电磁体的接触或分离。首先，我们使用传递矩阵法推导了带隙性质的理论解，并将其与有限元结果进行比较。然后，我们重点研究不同参数对带隙性能的影响，以了解如何对其进行有效调节。最后，为简化起见，我们考虑了结构和激励的对称性，得到了两个基本解，在此基础上，通过叠加获得了任意激励的带隙特性。结果表明，温度和电流可以有效改变带隙特性，虽然晶格常数和SMA弹簧刚度都具有全局性和巨大的影响，但普通的弹簧刚度和磁力都对带隙进行了局部和详细的修改。当结构化光束完全对称但受到反对称激发时，我们可以获得极低和较宽的带隙。此处设计的结构有望在主动控制的低频降噪中发挥作用。当结构化光束完全对称但受到反对称激发时，我们可以获得极低和较宽的带隙。预期此处设计的结构将在主动控制的低频降噪中发挥作用。当结构化光束完全对称但受到反对称激发时，我们可以获得极低和较宽的带隙。预期此处设计的结构将在主动控制的低频降噪中发挥作用。