Research On The Auxetic Property And Mechanical Properties Of Graphene Kirigami

The mechanical properties of graphene can be adjusted by the design of tailoring.Here,we report that the tailoring geometry parameters of graphene can tune the negative Possion's ratio.Several different kirigami structures including re-entrant honeycomb,arrowhead and star structures have been studied based upon the geometries of negative Possion's ratio.The main factor which contributes to the negative Possion's ratio for graphene kirigami is re-entrant angle,because of the bending deformation of the oblique ribs.In addition,the length of oblique ribs and straight ribs can influence the negative Possion's ratio for the re-entrant honeycomb.The arrowhead angle can also influence the negative Possion's ratio for the arrowhead structure.Our results provide insights into the negative Possion's ratio of graphene kirigami,which may be generally used in designing nano-electro-mechanical systems which require negative Poisson's ratio.Our research results are as follows:(1)The graphene kirigami of re-entrant structure exhibits the negative Possion'sratio.The negative Possion's ratio of graphene kirigami depends on the bending deformation of oblique ribs.The main factor which affects the negative Possion's ratio is the degree of the re-entrant angle along the tensile strain direction.(2)In contrast to the non-defective graphene film,the Young's modulus of the re-entrant graphene kirigami decreases.When the structure fractures,the tensile strength decreases and the tensile strain increases.Although,the tree different re-entrant structures graphene kirigami break at the different strains,the position of the fracture all occur at the oblique ribs where there is a re-entrant angle.Moreover,the shear modulus of three re-entrant graphene kirigami increases.