Architectural Tuning Of Graphene-Copper Artifical Nacre Based On Molecular Dynamics

Graphene exhibits fascinating physical properties in the fields such as optics,thermals,electromagnetism,and mechanics.However,the low-dimensional structure of graphene limits its further application in practical engineering as a structural material.Synthesizing graphene with common materials to obtain three-dimensional composites is an effective approach to partly resolve this issue.On one hand,the physical properties of graphene may result advanced functions to these composites.On the other hand,the graphene-matrix interaction may strengthen these composites.This is of great importance for the application of graphene in practical engineering.Considering graphene as an enhancer in metal matrix,the mechanical performance of graphene-metal nanocomposites can be significantly improved,and is affected by the architecture of graphene.Understanding the architectural effects on the mechanical properties is important for the design of graphene-metal nanocomposites.In particular,though tuning the architecture of graphene-metal nanocomposites,it is expected to fabricate nanocomposites with excellent mechanical properties.In this thesis,the research progress of graphene and its composite materials at home and abroad is firstly reviewed,and the theoretical basis of molecular dynamics simulation is introduced,and then based on the microscopic mechanism obtained by molecular dynamics simulation.The atomistic models of graphene-copper artificial nacres are simulated to explore the fracture of these composites with different architectures under tensile loading,and the underlying mechanisms of deformation,plasticity and failure are revealed.Combining molecular dynamics simulations and theoretical mechanical models,the strengthening and tough ening effects of graphene-copper interfaces are analyzed to obtain some fundamental principles for materials design.The Young’s modulus and fracture strength can be tuned by tailoring the architecture of graphene-copper artificial nacres(e.g.,the distribution of graphene fragments,and their size and spacing).The effects of graphene interfaces on the dislocation evolution of copper matrix are also studied according to molecular dynamics simulations.The results show that the dislocations will be blocked and cannot propagate through the graphene interfaces.This effect leads to a hardening process for copper,and impedes the plastic flow of graphenecopper artificial nacres.In summary,combining molecular dynamics simulation and theoretical mechanical models,the mechanical behaviors of graphene-copper artificial nacres under uniaxial tensile loading are studied in this thesis.The mechanisms of copper crystal orientations and architecture of nanocomposites affecting the mechanical properties of these composites are revealed.This thesis may provide some new insights into the further design of graphene-metal composites.