Improving the vibration control performance of metamaterial structures by the inclusion of nonlinear local resonators

Resumo

The use of periodicity has become an exciting solution for structural noise and vibration reduction in many engineering applications. Acoustic metamaterials are structures built using repetitive assemblies of identical elements to explore either Bragg-scattering or internal resonance to control mechanical waves. They present frequency bands in which waves do not freely propagate, named bandgaps, allowing acoustic and vibration attenuation at various frequency ranges. If properly designed and implemented, nonlinear stiffness can result in resonance frequency shifts that broaden the attenuation frequency band and better isolate subsystems that could be sensitive to higher excitation levels. This work investigates the effects of geometrically nonlinear local resonators on the low frequency bandgap formation of a metamaterial beam. Attention is paid to the realization of lightweight non linear resonators via additive manufacturing of compliant mechanisms as the nonlinear resonant unit. The proposed model is validated through simulations and experimental analysis. This investigation contributes to understanding improvements provided by nonlinear elements for vibration control of a metastructure.