Resonant-microstructure-based metastructures typically exhibit narrow effective bandwidths, and their operating frequencies are predominantly determined by the masses of the local resonators. This inherent limitation severely constrains the ability to manipulate low-frequency elastic waves. To overcome the limitations of mass dependence, an enhanced inertial amplification (IA) metastructure is proposed. The equivalent mass of the metastructure can be effectively increased without adding mass through the design of the linkages and hinges, thereby reducing the starting bandgap frequency and broadening the bandwidth. Eigenmode analysis further elucidates the physical mechanism underlying the formation of low-frequency bandgaps. Moreover, coupled bandgaps and strong wave-mitigation domains are obtained based on the spatial modulation of IA supercells. The proposed IA metastructure is employed to implement a one-dimensional topological insulator, thereby achieving low-frequency, robust, and wide-response-area topological interface states. This study is expected to promote the application of low-frequency, lightweight elastic-wave and acoustic devices in energy transport, energy harvesting, and vibration shielding.

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• Band gap
• Dissipative dynamics
• Elastic waves
• Topological effects in acoustic systems
• Acoustic metamaterials
• Mechanical metamaterials
• Topological insulators
• Transfer matrix calculations