Challenge toward nanometer scale fracture mechanics

For the past several decades, fracture mechanics concept and theories have been successfully developed and advanced in the engineering field as here we celebrate 50th anniversary of Engineering Fracture Mechanics. Fracture mechanics has now been expanded rapidly to the interdisciplinary including physics, materials science, biology and geophysics, etc., and is expected to advance further beyond the anniversary; such future advancement includes fracture mechanics in nanometer scales, where discreteness of atoms become dominant and the continuum-based conventional fracture mechanics might break down, in contrast to the great success of fracture mechanics in macroscale. This article thus aims to review experimental and combined with theoretical challenges of fracture mechanics toward nanometer scale, and discuss the future direction of fracture mechanics.