Active feedback control of elastic wave metamaterials

As an important extension of periodic structures and phononic crystals, elastic wave/acoustic metamaterials can show negative effective parameters for special frequency regions. Although the active control method is widely applied to the vibration isolation and elastic wave propagation, little attention has been paid on changing elastic wave/acoustic properties of metamaterials. In this work, a new kind of elastic wave metamaterials combined with the automatic control system is presented. Propagation behaviors of the elastic wave are discussed. To demonstrate the effect of the active feedback control, the stop band properties, tunable negative effective mass and control system stability are considered. The results show that the negative acceleration feedback control can enhance the frequency region that creates the negative effective mass. Moreover, the stability of this periodic structure can be achieved.