Programmable metamaterial with digital circuits for isolation of low-frequency vibration transmission

Controlling low-frequency vibration of structures is still a challenge in modern industries. Metamaterials with local resonators present bandgaps at sub-wavelength frequencies. Propagative waves are not supported within the bandgaps. Therefore, metamaterials are widely proposed for vibration reduction or isolation at low frequencies. However, metamaterials with passive resonators suffer narrow effective frequency band and lack of adaptivity. In this talk, a new type of smart metamaterial with online controllable bandgaps is presented. The studied metamaterial is composed of piezoelectric actuators and digital synthetic impedance circuits (digital circuits). The digital circuit contains a micro-controller. By programming the micro-controller, the circuit can establish any desired impedance between the terminals of the connected piezoelectric patch, therefore to program the dynamical behaviours of the designed metamaterial. In this sense, a programmable metamaterial is studied. Experiments are performed to study its programmable dynamical behaviours, with a particular focus on isolation of vibration transmission. Results demonstrate that the proposed smart metamaterial can be flexibly programmed online to isolate vibration transmission in beam structures at desired frequencies or within a large frequency band. The proposed programmable metamaterial conception can be naturally extended to other kinds of structures like plates and shells, they are promising components in the future adaptive structures.