ABSTRACT
Because they supply the main sources in the fracture of a bulk, the knowledge and concepts based on conventional continuum mechanics may give us a strong clue for the exploration of the nano-scale world. This is the top-down approach from macro-mechanics to nano-mechanics. On the other hand, considering the discrete internal structure due to the atoms, the definition of stress and strain based on continuum mechanics becomes ambiguous in nano-components. Thus, the lower applicable limit of the continuum mechanics concept is one of interesting issues under the top-down approach. We have to reconsider the definition of fracture and the mechanical parameters on the atomic scale. This requires the bottom-up approach from atomic mechanics (dynamics) to nano-mechanics. Not only the dislocation behavior but also the thermal activation of atomic motion plays an important role in the deformation and fracture processes of nano-components because it has strong size-dependence on deformation (e.g., diffusion creep).
