A Molecular Dynamics Study Of Fracture Strength Of Multilayer Graphene

Carbon atoms form a hexagonal two-dimensional carbon nanomaterial-graphene(Graphene)through sp~2 hybrid orbitals.It is a new material that is expected to replace silicon nanomaterials.The benzene ring structure researched by carbon atoms.It’s different stacking methods(ABC stacking,etc.)constitute a new two-dimensional material.Graphene is used in many advanced materials and devices due to its excellent mechanical,such as nanocomposites,transistors,mass and gas sensors,micromechanical generators,semiconductor device,mechanical systems.And graphene also has good thermal conductivity,high transparency and strength,large specific surface area,etc.,so in biosensor technology,catalyst carriers and other optical,electronic,information storage,energy materials and other fields have broad application prospects.The mechanical properties of graphene will directly affect its performance in all aspects,and restrict the stability and reliability of graphene nanodevices.In this paper,a classical molecular dynamics method is used to systematically study the mechanical properties of graphene nanoindentation.The contents are as follows:1.We used molecular dynamics method to simulate nano-indentation and calculated the fracture strength of multilayer graphene.The results show that the fracture strength decreases with the increase of the number of layers,and with the reduce of the number of graphene layers,the reduction rate of the failure strength changes in a step-like manner,the rate of change gradually slows down,and decreases rapidly in the 2-6 layers In the 7-13 layers,it decreases linearly at a slower rate,and after 13 layers it decreases more slowly.2.Based on the nanoindentation theory,we analyzed the structure,atomic distribution,atomic state,loading force-layer number curve of the multilayer graphene and the breaking force of the 2-19 graphene layers.The results show that the rupture force of the 2-6 layers increases rapidly with the number of layers,and the 7-13 layers increases at a smaller rate.When the number of layers is greater than 13 layers,the rupture force tends to be stable,and the maximum rupture force reaches 1800 n N.3.We have studied the multilayer defect graphene nano-indentation,and analyzed the breaking strength of three kinds of defect multilayer graphene: singer vacancy,double vacancy and Stone-Wales.The destruction strength of multilayer defect graphene and the mechanism of defects affecting mechanical properties were studied.The mechanical strength of multilayer defect graphene is related to the size and density of defects.