Abstract:

This paper presents a lattice sandwich metamaterial beam with embedded active mass-rubber resonators, enabling automatic bandgap tuning in response to the excitation frequency. Unlike existing tunable metamaterials that rely on open-loop thermal regulation, the proposed closed-loop frequency-temperature feedback control strategy achieves adaptive bandgap tuning with only an ultra-low voltage and a simple structural design. With the energy method, the dispersion relations and bandgap edges are analytically derived for the sandwich metamaterial beam. Experimental measurements are conducted to quantify the temperature dependence of the rubber elastic modulus and the resonator natural frequencies, as well as the correlation between the applied voltage and rubber temperature. From these relationships, a frequency-to-voltage transfer function that enables the required tuning voltage for any target excitation frequency within the operational bandwidth is derived. A closed-loop frequency-temperature feedback control strategy is then proposed to achieve bandgap adaptation. Both theoretical analyses and experimental validations confirm that the proposed frequency-temperature feedback control strategy enables adaptive bandgap control at extremely low voltages. The proposed metamaterial beam and the control method exhibit advantages such as structural simplicity, low voltage requirements, and high control efficiency, which can be used in a wide range of engineering applications such as active vibration suppression, broadband acoustic absorbers, and tunable metamaterial filters.

Key words: metamaterial, sandwich structure, active vibration control, local resonator, frequency-temperature feedback control