| Abstract: | Method of hybrid machining-tension simulations is proposed and applied to Cu (111) plane nanostructure basing on Molecular dynamics. The results show that atoms at frontage of and under tool deviate from their initial positions and form deformation zone in nanostructure. Dislocations only propagate in surface and subsurface when scratching depths are shallow, and some dislocations form dislocation loops as there exists stress gradient near tool. The number of residual defects increase and Order Degree of crystal structure decrease as scratching depths increase. There exist high residual stress in subsurface, especially near the position where tool withdraw nanostructure. After machining, tensile loads are applied to two ends of nanostructure. The response of initial loaded stage is elastic as a whole, while the stress-strain curves show local decrease as residual stress and defects from machining process result in movement of some atoms and onset of dislocations. The Yang's Modulus and yielding stress decrease as scratching depths increase. The initial plastic deformation of machined nanostructure are determined from dislocations slip and stacking faults, and conjugate slip planes ((1 1) and ( 1) slip planes) are formed at the two side of scratching groove. Dislocation slip results in the decreasing of stress, while pileup of dislocations and the forming of new slip plane result in the increasing of stress. As a result, the stress-strain curves decrease step by step. Order degree of nanostructure for first yielding and strain at 0.8 decreases as scratching depths increase, while Order degree of nanostructure for small scratching depths at the strain of 0.8 increase comparing to that of 0.045. |
