Analysis of all-solid to pore-solid structure bandgap optimization for novel acoustic metamaterials

Locally resonant phononic crystals are essential for the control of bandgaps. Historically, the focus on solid-structure construction has led to the neglect of the significance of pores. Therefore, without changing the initial geometric configuration and arrangement, this paper designs a snowflake-shaped all-solid structure and introduces pores with two modifications. Based on these models, band structure simulations and bandgap analyses are carried out. Subsequently, the propagation characteristics of elastic waves in the structure are described by using phase velocity and group velocity. Finally, the transmission curves of the finite-period structure are compared with the bandgap range of the infinite-period structure to verify the success of the structural optimization. By appropriately introducing pores and regulating the structure, in bandgaps below 1000 Hz, the performance of the structure can be improved to 2.5–4.5 times that of the all-solid structure; meanwhile, the phononic crystal becomes lighter.