A locally resonant elastic metamaterial based on coupled vibration of internal liquid and coating layer

摘要

In present work, a locally resonant elastic metamaterial (LREM) based on liquid solid interaction (LSI) is proposed, which can attenuate flexural wave in broad low frequency range. By using internal liquid as scattering core and thin layers as coatings, inertial and elastic components of the LREM are connected by LSI rather than cohesive material. This characteristic enables the LREM to be modified easily. A semi-analytical model of the LREM's unit cell is developed for studying its dynamic effective mass (DEM). Finite Element method is applied to calculate the band structure, DEM and transmission. A 3D-printed metastructure containing five unit cells is tested experimentally. Good agreements among theoretical, numerical and experimental results proved the LREM's capability to block vibration in broad low frequency regime. Parameter analysis has been conducted as well. Polar and zero points of the DEM would shift to lower frequency region when liquid's density increases and the normalized bandwidth would be broadened. A similar trend could be observed when the thickness of coatings reduces however the bandwidth would almost remain unchanged. Moreover, stronger initial tension stress would increase bending stiffness of coatings and the local resonance frequency. Furthermore, the internal liquid could hardly contribute to stiffness of the LREM nor could thin layers do on the inertial component. Those traits indicate that the proposed LREM could be quite applicable for vibration controlling in broad low frequency range. (C) 2019 Elsevier Ltd. All rights reserved.