Effect of strain rate on tensile strength of defective silicon nanorods

Abstract

The effect of strain rate on the tensile strength of defective monocrystalline silicon (Si) nanorods is studied with the molecular dynamics method. The strain rate applied to the nanorods is varied from 107 to 1014 s−1, and the atomic interactions among the Si atoms are described by the Stillinger-Weber (SW) potential functions. The tensile strength of the ideal Si nanorod is shown to be strongly strain rate dependent and increasing with the strain rate. The failure pattern also shows strain rate dependence, indicating that increased strain rates gradually suppress unsuitable relaxation and dissipation mechanisms because of the accompanying larger external loadings. Furthermore, the effects of intrinsic material parameters (i.e., the cutoff radius of SW potential function) and defects (i.e., inevitable surface defects and internal preinstalled defects) are investigated. It is revealed that the effect of strain rate on the tensile strength of Si nanorod is influenced by both the intrinsic physical properties of the material and the distribution of the initial defects, with specific surface defects appearing to be more important to nanostructure design.