Prediction of Fracture Properties of Graphene by Multiscaled Finite Element Simulation

  • 杜 瑜中

Student thesis: Master's Thesis

Abstract

A new approach of multi-scale finite element simulation is proposed to predict the fracture toughness and crack propagation in a single layer graphene sheet In this simulation MD-based nonlinear beam element is developed for the atomistic model near the crack tip whereas a plane element is employed for the continuum model in the far field of the cracked specimen The material and section properties required in the nonlinear beam element are estimated through the equivalence between the potential energy of molecular dynamics and the elastic strain energy of continuum mechanics With the estimated properties of beam element the material properties of plane element are further estimated by applying loads on the specimen of graphene which is formed by hexagonal lattice of carbon atoms Coupling the nonlinear beam elements by plane elements with the local-global concept of multi-scaled modeling a vast of computational time can be saved The accuracy of near-tip stresses obtained in this simulation remedies the inaccuracy of linear elastic fracture mechanics and can be used for the prediction of atomic bond-breaking which leads to crack propagation The associated critical load can then be applied in the continuum model for the cracked specimen to predict mode I and mode II fracture toughness of graphene The obtained values were then verified by the published results measured or predicted by the other methods By varying the size of cracks and orientation of applied loads several interesting phenomena have been observed and discussed in this thesis
Date of Award2018 Jul 18
Original languageEnglish
SupervisorChyanbin Hwu (Supervisor)

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