Mechanical properties of wrinkled graphene generated by topological defects

In a free standing graphene with topological defects, e.g. heptagons and pentagons, the out-of-plane wrinkles are generated to release in-plane deformation energy. In this work, different aspect ratios (amplitude over wavelength) of the wrinkled graphene sheet are obtained by adjusting the topological defects in the graphene sheet. Due to the geometrical locking effect, the interlayer shear mechanical properties are significantly increased by increasing the aspect ratio of the wrinkled graphene sheet. For example, the shear modulus and strength for aspect ratio ξ = 0.177 are 1106.79 MPa and 612.06 MPa, which are 13.5 and 31.1 times larger than the values of the flat graphene system, respectively. On the other hand, the in-plane tensile modulus and strength of the wrinkled graphene sheet are weakened caused by the decreasing of the tensile stiffness for wrinkled surface and large residual stress at the topological defects. Benefiting from the high interlayer shear modulus and strength, the assembling of the wrinkled graphene sheet can construct a graphene membrane with tensile strength up to 12.57 GPa. This work has proposed a new mechanism to enhance the interlayer load transfer capacity of graphene sheet which is helpful to the design of high performance graphene nanocomposites.