The effects of stress concentrators on strength of materials at nanoscale: A molecular dynamics study

There is evidence that when at least one spatial dimension of a material component is in the nanometer range, the effects of nanosize stress concentrators (NSCs) such as impurities, inclusions, pores, and cracks are either eliminated or significantly reduced. The aim of the paper is to examine such evidence using atomistic simulation techniques for a crystalline metal and identify the critical dimensions below which the effects of NSCs are minimal or even nonexistent. The preliminary results reported herein show that for Cu single crystals subjected to constant external strain rate, such critical dimensions are larger than about 30 nm. Since atomistic details are crucial in understanding material behavior at such scales, the paper points to the need for multiscale simulations techniques, presently being developed, for identifying critical dimensions and for examining slow strain rates. Based on the results, the paper presents simulation-based explanations why NSCs may be insignificant at nanoscales.