Static and Dynamic Characteristics of Nano and Microstructures

Gangele, Aparna and Pandey, Ashok Kumar (2019) Static and Dynamic Characteristics of Nano and Microstructures. PhD thesis, Indian institute of technology Hyderabad.

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Abstract

With the improvement in micro and nanofabrication processes, researchers are able to control the growth and fabrication of single or arrays of nanotubes or nanofibres. While single walled carbon nanotube (SWCNT) and double-walled carbon nanotube (DWCNT) are used for designing resonators, others used them in the form of arrays such as vertically aligned carbon nanotubes (VACNTs) to increase the surface area for other applications. When nanotubes are used as a vertically aligned form, the bulk properties change with respect to single SWCNT or DWCNT as these tubes are bonded together with interatomic non-bonded potential such as the van der Waals interactions. Moreover, under a given compressive loads, VACNTs buckle under different buckling load. Therefore, it is imperative to understand the variation of elastic and buckling properties of VACNTs with number of tubes under the presence of van der Waals potential between the neighbouring tubes. Since, the properties of SWCNTs and MWCNTs also depend on their configuration, the effect of configuration on elastic and buckling properties are also analyzed. In order to use excellent properties of carbon to improve the properties of other planer structures such as microelectromechanical system (MEMS) or nanoelectromechanical system (NEMS), many graphene-based MEMS/NEMS devices are explored. Thus, fracture properties and elastic properties of graphene silicon composites need to be investigated under the different configuration of graphene and different crystallographic conditions of silicon. Additionally, we also investigate the size effect on elastic properties of graphene-silicon nanocomposites. After finding mechanical properties under static condition, we also perform the vibrational analysis of graphene-silicon and horizontally aligned carbon nanotube-silicon composites with and without surface effects. Finally, we investigate the performance of nanofibers mat in tuning the frequency of hexagonal and rectangular shape microcantilever beams based on experimental and numerical results. The methodology developed in the thesis can be effectively used to model different types of carbon-based flexible substrate for the development of large area based sensors and actuators in the future.

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