Abstract Summary
Locally resonant metamaterials (LRMs), with periodic elements that exhibit local resonance, have been recently investigated by numerous researchers as a means to pursue vibration atten-uation and wave manipulation. These structures are able to generate bandgaps in specific fre-quency ranges depending on their mass, stiffness and geometrical characteristics; however, they present certain limitations when bandgaps in the low-frequency domain are sought, since they require heavy oscillating masses. This research work harnesses the potency of a novel dy-namic directional amplifier, namely the DDA, that is introduced as a means to artificially in-crease the inertia of an oscillating mass. The DDA is realized by imposing kinematic con-straints to the degrees of freedom (DoFs) of the oscillator, hence inertia is increased by cou-pling the horizontal and vertical motion and forcing the model to move along a circumference. Herein, the DDA is applied on the resonating mass of a scaled LRM structure, assembled using LEGO® components. Experimental and analytical calculations are subsequently undertaken to investigate the dynamic properties of this DDA-enhanced metamaterial. Results showcase the low-frequency attenuation properties of the structure and serve as a proof of concept of the mechanism.
