Load transfer in fractured carbon nanotubes under tension

The previous experimental evidence revealed that tensile fracture of a carbon nanotube (CNT) is triggered from the outermost layer of the graphene sheets, and then the crack grows toward the inner sheets. This work studies load transfer among the graphene sheets when a crack grows into the inner sheets. Both shear-lag modeling and finite element analysis (FEA) have been employed for analyzing the stress distribution in the graphene sheets. Numerical computations are given to the cases in which the wall numbers are two, five, and ten, respectively. The effects of the number of layers and the aspect ratio on the load transfer efficiency have been examined. The energy release and the effective Young's modulus of a fractured CNT with respect to the number of broken layers are computed. The stress concentration at the crack tip grows with the radial crack propagation. The increase in the interlayer shear stress leads to crack deflection that forms the sword-and-sheath type of tensile fracture. (C) 2011 Elsevier Ltd. All rights reserved.