Topological Rainbow Trapping of Plate‐Mode Waves Based on 1D Gradual Phononic Crystal Slabs

In this article, the concept of topological rainbow is introduced into the plate‐mode waves system of 1D phononic crystal slabs, achieving adjustable topological elastic rainbow trapping by employing gradient‐tuned Su–Schrieffer–Heeger (SSH) structures. First, based on the classical SSH model, a phononic crystal slab composed of steel and aluminum is set up, and the band structure of plate‐mode waves is studied using the finite‐element method. Band inversion can be induced by changing the height of the steel in the unit cell, leading to topological phase transitions. Then, phononic crystals with different topological properties are connected to form a phononic crystal slab, realizing topological interface states. Furthermore, a sandwich‐like ultrathin structure is constructed to couple the adjacent two topological interface states. Finally, a 1D alternating SSH structure of phononic crystal slab is designed under gradient structural parameters, and based on eigenfrequency and full‐wave simulation, adjustable topological rainbow trapping based on coupled interface states is achieved. The designed device can trap wide frequencies exceeding 15 kHz, providing more possibilities for the design of elastic‐energy‐harvesting devices. Topological rainbow in 1D phononic crystal slabs, achieving adjustable elastic trapping using gradient‐tuned Su–Schrieffer–Heeger structures, is introduced. By varying steel heights, band inversion induces topological phase transitions, forming interface states. A sandwich‐like structure couples these interface states, enabling rainbow trapping frequencies exceeding 15 kHz, outside the common bandgap, expanding design possibilities for energy‐harvesting devices.