VIBRATION ANALYSIS OF CNT REINFORCED NANO COMPOSITES

Abstract

Since the discovery of CNTs, they have been the focus of frontier research. Carbon nanotubes are in the form a single or nested structure having tube diameter in nanometer scale and important material responses are observed at the discrete level. The tensile strength of the CNT has been found close to 100 GPa and their Young‟s modulus are in the range of terapascal which is superior than conventional carbon fibres.It has opened vast areas of research which also include nanoscale reinforcements in composites in order to improve their mechanical, thermal and even electrical properties. The enhancement in material properties of composites due to addition of CNTs depend upon the volume fraction, dimensions such as length, diameter, thickness etc of CNTs and their orientation in the matrix material. The current research in composites has indicated that CNT reinforcement in polymer based composites can substantially enhance the various mechanical properties, as it plays the role of matrix additives and provides multifunctional properties to the composites. Computational methods have been increasingly used in the recent years and the difference in length scale is compensated using computational techniques. Modelling and simulations of nanocomposites are being achieved on desktop computer with relatively less cost. The accuracy of mathematical models will determine the results obtained through computer simulations. The important approaches for the modelling of nanocomposites are molecular mechanics, continuum modelling and multiscale modelling . CNT reinforced composites have a wide range of applications such as automobiles, aerospace, marine etc where they are often subjected to high vibration loads. Therefore study of dynamic response of CNT composites is very much essential for analyzing its suitability for varied applications.. In the present study Continuum mechanics approach has been utilized to model CNT reinforced polymer composites. The present work aims at studying the influence of CNT reinforcement on the mechanical properties as well as the dynamic response of polymer based nano composite material. Finite Element Analysis is carried out to analyze the response of polymer CNT composite under different loading environment .The effect of volume fraction, length and thickness of reinforced CNT on the material constants of composite are presented in this study. The results predict that there is appreciable increase in stiffness of composite along the axial direction of reinforced carbon nano-tube .This study also includes the response of CNT epoxy composite under thermo-mechanical loading. Modal Analysis of a hexagonal representative volume element for CNT epoxy iv composite is carried out in this study to evaluate the effect of CNT reinforcement on the mode shapes and natural frequencies of composites. The vibration analysis of CNT epoxy composites have been carried out under harmonic loading for different volume fraction and orientation of CNTs to evaluate its response under varying frequency loads. The results of study shows that reinforcement of CNT in Epoxy matrix increases the frequency corresponding to maximum displacement thus improving the capacity of structure to withstand load at higher frequency without resonance.