Visco-elastic properties of carbon nanotubes and their relation to damping

Abstract

In this presentation, we discuss semi-analytical approaches to the visco-elastic properties of the Carbon Nanotubes (CNTs) based on molecular dynamics (MD) simulation and continuum models. The visco-elastic properties of the CNTs defined in both the time and frequency domains have been obtained in terms of the creep compliance and the relaxation and complex modulus. The equilibrium visco-elastic properties were found to be strongly dependent on tube radius for both single-walled and multi-walled CNTs, while the chirality had no appreciable effect. For multi-walled CNTs, the interlayer interaction contributes significantly to the overall visco-elastic response. The time scale associated with the visco-elastic properties were found to be on the order of nanosecond. This time scale is reflected in the associated energy loss and damping mechanisms in CNT oscillators. From the computed visco-elastic properties, we further derived the quality factor Q for different tube geometries and load frequencies. We found that the Q factor is strongly influenced by the load frequency, in addition to the dependence on the tube radius. The predicted trends in terms of the dependence on the load frequency were further validated through comparison with experiments. The underlying mechanism for such trends was discussed in the context of thermoelastic theory. ©2010 Society for Experimental Mechanics Inc.