Vibration attenuation in 3D-printed metamaterial plates with graded embedded resonators

Thin-walled structures provide high structural efficiency with reduced weight, but their limited flexural stiffness makes them susceptible to vibration amplification under dynamic excitation. To address this limitation, this study proposes a single-phase 3D-printed elastic metamaterial (EM) thin plate with embedded resonators to generate low-frequency flexural band gaps through local resonance. The novelty of this work is the experimental assessment of the spatial grading of the resonators’ geometric parameters, a strategy not yet directly addressed in single-phase EM thin plates with empty cavities. The investigation combines a shell-based finite element method (FEM) model with dynamic impact tests on 3D-printed prototypes. Band structures are computed using Floquet-Bloch periodic boundary conditions, and frequency response functions (FRFs) are obtained for finite plate models. The EM thin plate exhibited two complete flexural band gaps, but only the first produced relevant vibration attenuation in the FRFs. The parametric analysis showed that, across different geometric configurations, the first band gap could be positioned between 129.12 and 5326.35 Hz, with bandwidths of up to 820.10 Hz. The non-graded experiments showed attenuation regions close to the numerical predictions, supporting the local-resonance mechanism of the embedded resonators. In the graded models, geometric grading preserved and broadened the main attenuation zone when two parameters were graded simultaneously, although with reduced depth and greater sensitivity to fabrication deviations. Thus, this study provides an experimental assessment of the potential and limitations of geometric grading in embedded resonators for tailoring flexural vibration attenuation in single-phase EM thin plates.