Numerical and Experimental Study of Local Cell Resonators to Obtain Low-Frequency Vibrational Stopbands in Periodic Lightweight Structures

Abstract

Periodic lightweight structures, such as honeycomb core panels, combine excellent mechanical properties with a low mass, becoming attractive for application in transport and machine design. However, the high stiffness to mass ratio of these lightweight structures may result in unsatisfactory dynamic behaviour in that it may impair the panels’ ability to reduce noise and vibration levels. Liu et al. demonstrated that inclusions of high density spheres with a rubber coating in a matrix material result in low-frequency sound isolation, breaking the mass law [1]. These locally resonant sonic materials require a high density of local resonators throughout the matrix material, either spread randomly or periodically. In this paper, resonating structures are introduced into the cavities of a honeycomb structure, leading to a material with excellent mechanical properties and strong structural attenuation in a low-frequency region. By means of both numerical models and experimental measurements, the potential of local cell resonators for periodic panels is shown.