Investigation of carbon nanosprings with the tunable mechanical properties controlled by the defect distribution

Abstract The effect of defect distribution and pitch length of carbon nanosprings fabricated by different construction methods on their tensile and compressive mechanical properties is comprehensively studied. Twelve examples of nanosprings with various defect distribution are constructed according to three widely used methods based on two parent toroidal carbon nanotubes (TCNTs). Their mechanical performances are studied by using molecular dynamic (MD) simulations through tensile and compressive tests. The results reveal that the spring constant, ductility, strength, gravimetric energy density and deformation process obviously depend on the defect distribution, indicating that the mechanical properties of nanosprings can be enhanced greatly by skillfully introducing defect distribution for specific purposes. Remarkably, the tensile stiffness (1.89∼68.13 nN/nm) and ductility (84%∼794.8%) can be adjusted by changing the defect positions and geometries of nanosprings. The force-strain curves of nanosprings under tensile loads show sawtooth-like patterns and the oscillations of force-strain curves can be controlled by the defect distribution to produce the high energy absorbing capacity. Furthermore, all nanosprings show excellent reversibility under compressive loads, and energy storage densities ranging from 53.31 to 859.67 J/g are achieved by adjusting the defect distribution and pitch length. The findings are meaningful for scientists to design carbon nanosprings with high performance.