Vibration analysis of sandwich structure with auxetic and non -re entrant honeycomb core using finite element methods and experiments

Abstract

The present finite element-based method is intended to analyse the interactions between the unit cell dimensions of cellular structures especially in the form auxetic honeycomb cores and the free vibration response of sandwich panels. The sandwich panels are assumed to be composed of an auxetic honeycomb metallic (Titanium or Aluminium) core and enveloped by two composite face sheets with a PMMA matrix and reinforced by carbon-nanotubes (CNTs). The deformations of the sandwich panels are modelled using a higher-order shear deformation theory considering seven degrees of freedom at each node of the finite elements. The effective properties of the CNT reinforced face-sheets which are dependent on the working temperature and CNT grading pattern are evaluated based on the extended rule of mixture. The properties of the auxetic honeycomb core are however dependent on the spatial orientation of the unit cells of the auxetic pattern and accounts for the anisotropic nature and Negative Poisson’s Ratio (NPR) of the metallic core structure. The influence of crucial parameters like the core metal, twist angle, plate-aspect ratio, core to face-sheet thickness ratio, rotational speed and unit cell dimensions of the auxetic honeycomb core are analysed .Experiments were performed to find the natural frequency