▎ 摘　　要

In this letter, we adopt the molecular dynamics method to study Young's modulus of 1-19 layers graphene by the nanoindentation theory and the tensile theory. The results show that the number of layers has a strong influence on Young's modulus using the nanoindentation theory, while Young's modulus from the tensile theory is not sensitive to the number of layers. Furthermore, we analyze the structure of multilayer graphene (MLG), the loading force-layer number curves, and the breaking force of 1-19 layers graphene based on the nanoindentation theory. The results reveal that MLG transforms into bulk graphite with an increase in the number of layers, which indicates that the nanoindentation theory has reached a limitation. Moreover, we simulate the nanoindentation for circular membranes of different radii and determine the threshold layer of the nanoindentation theory. Our study plays an important role in deepening the understanding of the mechanical properties of MLG and developing the nanoindentation and tensile theories. Published under license by AIP Publishing.