Jun 23, 2014
Applicability of the classic elastic models at the nanoscale
Five-fold twinned nanowires possess many enhanced mechanical properties for use as high-frequency resonators/actuators in various nano-devices. Developing efficient models to predict the mechanical vibrational properties of these nanowires is of great importance for better application. Using atomistic simulations and continuum predictions, researchers at the Dalian University of Technology in China have investigated this. Reporting in Nanotechnology, they demonstrate that the classic elastic models could be applicable to describe the small vibration of five-fold twinned copper nanowires if the most effective elastic moduli are provided.
Classic elastic models based on continuum assumptions have been widely used to model the mechanical behaviours of various materials and structures at the macro- and microscale. When the characteristic size of materials and structures decreases down to the nanoscale, it is often controversial as to whether these models are applicable. This is because nanomaterials and nanostructures possess discrete natures.
Based on atomistic simulations, however, it has been found that the collective mechanical behaviour of atoms is continuum-like and thus the classic models are expected to be appropriate. The key to ensuring the applicability of the classic elastic models at the nanoscale is to find the effective material properties, such as the Young’s modulus and shear modulus.
The size-dependent effective elastic moduli of five-fold twinned copper nanowires have been predicted by atomistic simulations and they can be well described by the empirical core-shell composite models. Researchers further compare the simulation results and continuum predictions. Provided that the effective Young’s and shear moduli are used, the classic elastic models cope with the small vibration of five-fold twinned copper nanowires very well.
Design of applications
These findings could allow for the construction of an effectively and efficiently hierarchical multiscale coupling method of atomistic and continuum theories to model large systems composed of many nano-components. This could be of practical importance for the design of five-fold twinned nanowire-based vibration nano-devices.
More information about the research can be found in the journal Nanotechnology (in press).
About the author
Yonggang Zheng is an associate professor at the Dalian University of Technology in the department of Engineering Mechanics. His current research interests are the mechanical behaviours of nanostructured materials and the development of multiscale computational methods.