Mode Conversion Between Symmetric and Shear Horizontal Plate Waves in Valley Topological Phononic Crystal Plates

Topological modes are well‐known for their robust and directional wave transportation. However, the symmetric Lamb and shear horizontal waves are precious in topological wave systems. These guided waves in a plate are promising in fields like wave communications and nondestructive testing. In this work, a valley topological phononic crystal plate that supports symmetric plate modes, e.g., zero‐order symmetric Lamb (S0) and fundamental shear horizontal (SH0) waves, is constructed. The proposed structure is efficient for controlling the mode conversion between S0 and SH0 modes. The mode conversion is governed by the weight ratio of displacement components of the topological edge states (TES) branches. The remarkable feature, i.e., robustness, of TES of symmetric plate modes is also demonstrated. These results provide an efficient way to control the wave components feasibly.