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During the past decade, metamaterial-based vibration energy harvesters (meta-VEHs) have been increasingly developed owing to the extraordinary characteristics of metamaterials, such as locally resonant bandgap, defect state, and wave focusing features. In this paper, the interface state, a feature recently found in topological metamaterials, is exploited for low-frequency vibration energy harvesting. The topological meta-VEH consists of two kinds of locally resonant metamaterials with different topological phases and a piezoelectric transducer being installed at the interface between these two metamaterials. First, the governing equations of the topological meta-VEH are established based on the mass–spring model. Subsequently, the dispersion relation of such a one-dimensional topological meta-VEH is obtained by applying Bloch's theorem. It is revealed that the interface mode can be attained in the low-frequency range through the band folding of the locally resonant metamaterial. Moreover, the finitely long model of this topological meta-VEH is built, and the transmittance response is calculated both analytically and numerically. Subsequently, the potential benefits of topological metamaterial, including wave localization and topological protection, are thoroughly investigated. It is found that the elastic energy in the interface state is localized at the interface position, resulting in a significant improvement in output power. Meanwhile, the topological protection property can significantly improve the robustness of the interface mode, thus achieving outstanding energy harvesting performance. Finally, to further enhance the energy harvesting performance, the stiffness tuning method and the defect enhancement method are proposed. It is found that integrating the defect mode and interface mode not only improves the output voltage but also achieves the capability of a highly robust energy harvesting. [ABSTRACT FROM AUTHOR]

• An innovative topological metamaterial is presented. • Tuning local resonators opens a chance for realizing polarization transition. • Three polarization transition points have been determined. • The topology properties and invariants are thoroughly investigated. Developing the acoustic-elastic analogy of a topological insulator has attracted extensive research attention in recent years. Designs developed in the literature strongly rely on reforming the host structure of a system to achieve topology transition. In this article, an innovative topological metamaterial is presented. Unlike topological phononic crystals, the proposed topological metamaterial has a uniform host structure without any phononic crystal features. The band inversion and polarization transition are achieved by manipulating the design of local resonators. It has been proven that by changing the coupling spring constant of local resonators, the mode topologies at the bound states associated with the band gaps can be converted. Three polarization transition points have been found from the bound evolution analysis, and all of them possess the capability of stimulating topological interface states in the corresponding band gaps. The Zak phase calculations have further ascertained the prediction about the topological interface states. The band structure and transmittance spectrum of a supercell lattice of the proposed topological metamaterial have been examined. The topological interface states, as well as the energy localization effects, have been successfully observed in all the three band gaps. The proposed metamaterial brings the convenience of creating topological interface states by carefully manipulating the local resonators only. The methodology presented in this work is thus of practical significance in transforming existing structures into topological systems without revising them. [ABSTRACT FROM AUTHOR]