Thin-walled box metabeam with graded 2DOF resonators for ultra-broadband complete flexural vibration suppression

Abstract

Traditional vibration suppression structures often struggle to achieve a balance between high load-bearing capacity and effective low-frequency vibration suppression performance. This study proposes a metabeam constructed by attaching graded two-degree-of-freedom (2DOF) local resonators to a host thin-walled box beam with high load-bearing capacity. Unlike conventional metabeams that involve the external attachment of resonators, the 2DOF resonators considered in this study can be simply embedded within the box beam, thereby conserving space. By utilizing the spectral element method (SEM), which provides exact solutions in the spectral domain, we analytically demonstrate that the 2DOF resonator is helpful to achieve a wider vibration reduction band than the conventional single-degree-of-freedom (SDOF) resonator. Based on a comprehensive parametric analysis, a metabeam with graded 2DOF resonators is designed and fabricated. Experimental measurements confirm that the metabeam can achieve ultra-broadband low-frequency flexural vibration suppression under multi-directional excitation. Notably, the vibration attenuation bandwidth of the proposed metabeam with graded 2DOF resonators is approximately twice that of a conventional metabeam with periodic SDOF resonators.