抄録
We investigated the applicability of fracture mechanics based on the continuum theory at the nanoscale, where only a small number of atoms are included in a singular stress field near a crack tip. We performed molecular statics simulations for pre-cracked nanoscale specimens with plate geometry. When the specimen width W is larger than 80 nm, the crack propagates at the stress intensity factor reaching fracture toughness K_<IC>. This indicates the fracture mechanics criterion successfully describes fracture at that scale. However, as the W is smaller than 40 nm, the stress intensity factor at the fracture clearly deviates from K_<IC>. This suggests that fracture mechanics loses its validity for the specimen smaller than 40 nm. Thus, identified the lower applicable limit of fracture mechanics is around W=40 nm.
