Investigation On The Mechanical Properties Of Graphene Kirigami And Nanoporous Graphene

Graphene is a new kind of two-dimensional carbon nanometerial with single atomic layer thickness,and it is regarded as a new generation of strategic materials so that graphene has been raised hot all the time from it is discovered in the year of 2004.Until now,people can produce graphene with high quality and large scale by the method of chemical vapor deposition(CVD)and so on.The research of pristine graphene has become mature,including its excellent mechanics,calorifics,magnetism,and the electrical properties,etc,which make it is expected to be high performance in the application for the fields of nano electronics,composite materials,energy storage and so on.Moreover,the research on the composite material composed of graphene and bulk metal or ethoxyline resin has made initial progress.Notably,the study on the defected graphene's properties has attracted more and more focus from the very beginning,for example,graphene kirigami(a special manufacturing processes)can increase the small limit strain of pristine graphene,and improve it's ductility;the remarkable practical properties of nanoporous graphene(NPG)have extended the practical fields to the microcosmic filtration,such as DNA-based detection.Molecular dynamic simulation is a relatively mature method,it can truly simulate the dynamic behavior of micronano materials under different loading,thus obtain the material's mechanical properties.It has been widely applied in the mesoscopic material performance research,and obtained a wide range of identity.In this paper,single/double graphene kirigami and nanoporous graphene(with different geometrical parameter)are studied with the method of molecular dynamic simulation tool(LAMMPS)on its deformation and fracture.With the MD visualization software VMD,the deformation until fracture process was observed.By drawing the axial tensile stess-strain curves of the simulation data,we attained the deformation and failure mechanism of two kinds of graphene.Finally,establishing different structures with different geometrical parameter and then appling tensile load on the structures,we obtained the variation tendency that mechanical parameters(Young modulus,fracture stress,fracture strain)vary with geometrical parameter.By the comparison,we demonstrate that the kirigami craftwork do increase the limit tensile strain 3 to 6 times,in other words,advance the stretchability.Moreover,by the summarize of the variation tendency of mechanical parameters changing with geometrical parameter,a conclusion was drawn that can effectively adjust the limit stain of the graphene kirigami,and the mechanical performance parameters can be controlled.This will lay a theoretical foundation of the application of the graphene in the flexible device.The research of bilayer graphene kirigami shows that the kirigami craftwork can also improve the limit tensile strain of bilayer graphene.Moreover,the deformation law of bilayer graphene kirigami is similar to monolayer graphene kirigami.Studies on the nanoporous graphene show that although the existence of the nanopores on the NPG decrease the intensity of graphene,we can reasonably adjust the value of three geometrical parameters to maintain the high-strength advantage of graphene.Moreover,we can change the value of mechanical parameters to satisfy the application demand by effectively altering the value of geometrical parameters.The ultimate strain,ultimate stress and Young's modulus of the porous graphene decrease with the increase of the density of the holes perpendicular to the tensile direction.And the stiffness of nanoporous graphene decreases with the hole density strictly.This results will serve as a powerful reference to the design of application field with NPG.