Novel resonator concept for improved performance of locally resonant based metamaterials

In the context of noise control engineering, locally resonant metamaterials (LRMs) have gained significant research attention over the past two decades due to their ability to combine lightweight, compact design with excellent noise and vibration insulation performance in targeted frequency ranges, known as stop bands. This paper proposes a novel resonator concept that achieves a high modal effective mass (MEF) for out-of-plane bending, aiming to widen the stop bands in LRMs. First, the dynamic motion of an idealized double-lever system, which inspired the resonator design, is analyzed. Then, a realizable resonator design is presented, along with an optimization scheme that maximizes the MEF, achieving values as high as 96.5%. The proposed resonator concept is used to develop an LRM solution to enhance the acoustic insulation performance of a structure relevant to the aerospace industry, yielding improvements of up to 9 dB in the frequency band of interest. Experimental results demonstrate that the designed LRM solution significantly improves the vibroacoustic response of the system. Future work will consider additional aspects of the optimization process, including manufacturing constraints, costs, and robustness.