An adaptive metamaterial beam with hybrid shunting circuits for extremely broadband control of flexural waves
A great deal of research has been devoted to controlling the dynamic behaviors of phononic crystals and metamaterials by directly tuning the frequency regions and/or widths of their inherent band gaps. Here, we report a new class of adaptive metamaterial beams with hybrid shunting circuits to realize super broadband Lamb wave band gaps at an extreme subwavelength scale. The proposed metamaterial is made of a homogeneous host beam on which tunable local resonators consisting of hybrid shunted piezoelectric stacks with proof masses are attached. The hybrid shunting circuits are composed of negative capacitance and negative inductance elements connected in series or in parallel in order to tune the desired frequency dependent stiffness. It is shown theoretically and numerically that by properly modifying the shunting impedance, the adaptive mechanical mechanism within the tunable resonator can produce high pass and low pass wave filtering capabilities for the zeroth order anti symmetric Lamb wave modes. These unique behaviors are due to the hybrid effects from the negative capacitance and negative inductance circuit elements. Such a system opens up important perspectives for the development of adaptive vibration or wave attenuation devices for broadband frequency applications.