Low-frequency band gaps within a local resonance structures

Local resonance structure (LRS) can effectively suppress wave transmission, but the design of LRS with tunable band gaps is still a challenge. This work proposes an LRS with two tunable band gaps, where the first bandwidth is successfully enlarged almost five times, and finally a low-frequency broadband with 60-420 Hz is obtained with the second disappearing because of the remarkable modification of band gaps obtained only by adjusting the stiffness rather than by large deformation or changing geometric configuration in traditional methods. The mechanism of tunable band gaps would have important implications for designing metamaterials with broadband, and potential applications for vibration and noise attenuation.