Vibrational analysis of Ag, Cu and Ni nanobeams using a hybrid continuum-atomistic model

Abstract

An important issue in the study of the nanostructures behaviors is the surface effects, which increases with the increase of the surface-to-volume ratio. Continuum theories are capable of modeling structures at micro and larger scales with enough precision and low computational costs. However, these theories are unable to predict the mechanical properties of nanostructures accurately. On the other hand, due to their high precision, atomistic modeling techniques are extensively employed for the study of systems at nanoscale; however, computational costs of these techniques are relatively high. In this research, we aim to study the vibrational behavior of nanobeams made of three FCC metals; silver, copper and nickel, for different boundary conditions. For this purpose, we develop a model which benefits from the advantages of both continuum and atomistic models. Along this line, in this research a core-shell composite model for the nanobeams is developed in which parameters of the model including the surface layer parameters such as surface elasticity, stress, and density are obtained using molecular dynamics simulations results based on genetic algorithm optimization. Subsequently, we have employed this hybrid continuum-atomistic model to predict the vibrational properties of nanobeams. Based on the conducted simulations, the error of the proposed calibrated core-shell composite model in predicting the vibrational frequency of nano beams is less than 3%, while the error of the classical continuum models without the surface effect is up to 50%.