The Molecular Dynamics Study Of Mechanical Properties Of Multilayer Graphene

Like the monatomic layer of graphite,carbon atoms in graphene are arranged in a way that bonds are formed by sp~2hybridized orbitals.The benzene ring structure of multilayer graphene is a periodic structure formed by the way carbon atoms are packed tightly together.Its different stacking forms constitute a new type of two-dimensional material(including AB stacking AA stacking and ABC stacking,etc.).Due to the specificity of the above nanostructures formed its excellent properties,graphene can be used in many advanced materials and devices,such as LCD touch material,thin film materials,piezoelectric material,microelectronic devices,energy storage materials and composite materials.In addition,graphene also has good thermal conductivity,extremely high strength,tall transparency and big specific surface area.So,graphene has broad application prospects in the fields of optics,electronics,information stored,energy materials,such as biosensor technology,field effect transistor,solar cells,supercapacitors and catalyst support.In this paper,we will conduct a comprehensive study on the mechanical properties of multilayer graphene using the molecular dynamics theory.The contents are as follows:1.The Young's modulus of 1-19 layers graphene was calculated by using nanoindentation theory.The results show that the Young's modulus is kept around 1.00TPa when the number of layers is small.However,when the number of layers is large,the Young's modulus tends to decrease and the number of layers has a great influence on the Young's modulus obtained under nanoindentation.2.Secondly,the Young's modulus of 1-19 layers graphene was calculated using the tensile theory and its value varied between 1.06 TPa and 1.09 TPa.The Young's modulus obtained by the tensile theory does not change with the increase of the number of layers.3.Based on nanoindentation theory,the structure of multilayer graphene,loading force-layer number curve and the fracture force of 1-19 layers graphene were analyzed.The results show that the multilayer graphene is transformed into block graphite as the number of layers increases,which indicates that the nanoindentation theory has reached a certain limit.In addition,we simulated nanoindentation process on the radii of different circular film and obtained the threshold layer of nanoindentation theory.4.The failure strength of 1-10 layers graphene was calculated and simulated.According to the simulation results,the failure strength of 1-4 layers graphene decreased rapidly and the failure strength of 2-5 layers graphene decreased at a smaller rate.The reason is that graphene shows earlier and more obvious nonlinear elastic behavior as the number of layers increases.5.The influence of interlayer slip of multilayer graphene on mechanical properties was simulated and it was found that slip has a certain effect on failure strength.Besides,The effects of three kinds of defects on the mechanical properties of multilayer graphene were simulated.The results show that the failure strength of multilayer graphene with different defects all decreased and indicate that the defect has a certain impact on the failure strength of graphene.