A smoothly tunable shape memory metamaterial with adaptive bandgaps for ultra-wide frequency spectrum vibration control

This article presents a smoothly tunable shape memory elastic metamaterial with adaptive bandgaps enabling the broadband frequency vibration control. The underlying bandgap-tuning mechanism arises from the reversible large deformation induced by shape memory alloy (SMA) element under electro-thermal loads, through which, various microstructural shape morphing could be achieved. Via delicately designing the unit cell, the numerically obtained band structures and effective medium properties display a successful attainment of the vibration stop-passing band formation and smoothly controllable two-way tuning phenomenon for a series of transitional and intermediate status. The overall controllable frequency scope could be shifted over an ultra-wide band. Subsequently, a systematic parametric study is carried out to unfold the bandgap-adjusting patterns by altering the apparent structural stiffness and the SMA elastic modulus, individually. The finite element harmonic analysis of a metamaterial unit-cell-chain model is further investigated to verify the effectiveness of vibration suppression and the variability of the stopband region from the frequency spectra and the equivalent stresses images. Finally, the experimental demonstration is performed to validate the numerical predication from a practical perspective. The proposed design may possess enabling application potentials for future active vibration control and noise isolation in engineering facilities.