Locally resonant mechanical dome metastructures for bandgap estimation

Abstract

In this work, the vibration transmissibility behavior of novel dome shaped auxetic structures with different cellular configurations are simulated using Abaqus 6.14 and subsequently studied experimentally. The dynamic behavior of domes and hourglass shape auxetic structures are studied within the frequency bandwidth of 5-500 Hz by using base excitation technique. The auxetic samples are subjected to broadband excitation at low dynamic strain, followed by sine sweep around the resonance of the system. The dynamic and modal behaviors are experimentally analyzed by using 3D Laser Doppler Vibrometer. The system is shown to develop specific wave propagation and attenuation bands, outline of which is important for developing strategies for damping/energy harvesting. Further, analysis has been carried out to analyze the mechanical wave propagation behavior when the system is subjected to broadband excitation frequency at low dynamic strains. Here, we have arranged a large periodic repeating units of hourglass shape auxetics with lumped mass inside it placed at the center. The equivalent spring-mass-damper mechanical circuit has been developed for the shake of simplifying our system. The Non-linear stiffness of hourglass structure depend upon constitutive cellular cells i.e. auxetic, regular honeycomb and plane, which is evident for getting broader bandgap formation than the linear one. The lumped mass is considered here as locally resonating metamaterial enabling low-frequency vibration attenuation. Furthermore, the analysis is being done for bandgap expressions depending upon the added mass ratio and target frequency. Further study is proposed for attenuation and transmission band analysis to steer the waves which roots the idea of vibration sink, in which we can damp the mechanical waves effectively at a specific location. The Auxetic meta-materials are envisaged to have a significant role in wave attenuation and wave steering, and can be used effectively for vibration control.