Computational and experimental investigation of the bandgap formation in 3D printed metastructures
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Date
2026-03-05
Authors
Στεργίου, Στέφανος
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Abstract
This thesis investigates the uniaxial vibration attenuation exhibited by a specific 3D printed metastructure.
Mechanical metamaterials and the structures they form (metastructures) offer an innovative approach to vibration attenuation. Metastructures incorporate internally embedded resonators and are characterized by precise architecture, a feature that has been made significantly more feasible through 3D printing. They exhibit local resonance effects when their resonators are excited and oscillate near their natural frequencies. These effects generate frequency ranges (frequency bandgaps), within which vibration transmission through these structures is strongly attenuated. This bandgap formation mechanism is associated with the unique macroscopic properties of negative effective mass and negative effective stiffness of metastructures.
The study focuses on a specific 3D printed metastructure consisting of ten periodically arranged internal resonators along its length. Through FEM simulations and experimental investigations, it examines the bandgap formation this metastructure exhibits for uniaxial vibration attenuation.
Firstly, convergence study was performed for the metastructure, and accurate material properties were assigned to its parts for ensuring the validity of the FEM models presented in the analysis.
By modifying the transverse natural frequency of the resonators through changes in their beam dimensions, the bandgap was tuned around the natural frequency of the blocked absorber case (i.e. the case where the resonators behave as systems with suppressed transverse motion). In this way, the bandgap formation mechanism was able to attenuate the high-amplitude vibration of the metastructure.
Additionally, by introducing small progressive variations to the natural frequencies of the resonators through modifications of the infill ratio of resonators’ concentrated masses, bandgap widening was achieved. Four different resonator distributions within the structure were examined, and the configuration exhibiting the most effective bandgap was selected for 3D printing and experimental investigation.
Finally, the effect of the progressive top-to-bottom release of the transverse oscillations of the resonators to this wider bandgap was highlighted. It was observed that the bandgap became more pronounced and wider, underlining the influence of the distinct resonators’ natural frequencies and of the number of resonators on the bandgap formation.
Throughout the analysis, good agreement was observed between the FEM simulations and the experimental results.
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Keywords
Metastructures, Resonators, Vibration attenuation, Frequency bandgap, FEM simulation, Experiments