Designed honeycomb lattice for improving vibration control

Honeycombs represent common cellular structures characterised by two-dimensional arrays of unit cells arranged in-plane and stacked parallelly in the out-of-plane direction, exhibiting a periodic structure. Due to the interconnected network of these unit cells, honeycombs possess higher porosity and lower mass density than their matrix materials, resulting in superior specific stiffness/strength and specific energy absorption. The arrangement of repeating unit cells profoundly impacts the mechanical properties of these lightweight materials. This study explores a 2D metamaterial cellular system inspired by the lightweight characteristics of honeycombs. In this system, squared honeycomb cells with additional lumped masses can influence vibrating modes. Unlike conventional methods employing discrete mass-spring resonators, this approach intentionally adds masses to create complete or incomplete stop bands wherein wave propagation is either wholly or partially suppressed along specific directions. The dispersion curves of wave bands and the sensitivity of bandgaps concerning design parameters are estimated using the finite element method and Block's theorem. Numerical simulations demonstrate the stop band behaviour, providing insights for optimisation strategies and a deeper comprehension of these remarkable cellular material systems and improvements in the design with enhanced vibro-acoustics performance and control.