A nano-orthogonal cutting model based on a modified molecular dynamics technique

Abstract

A proposed method based on combining the concepts of shape functions of the finiteelement method (FEM) and a molecular dynamics (MD) technique was developed toevaluate the chip formation and strain and stress distribution in the cutting ofsingle-crystal copper by a nano-scale mechanism. The displacement components for theatom in any temporary situation during the nano-scale cutting could be found.In this paper, the atom is regarded as a node and the lattice is regarded as an element.Using the atom displacements calculated by the MD program and combining the conceptsof shape functions of FEM we calculate the equivalent strain for material deformation inthe atomic-scale cutting mechanism. The equivalent stress was derived from the equivalentstrain from the corresponding flow stress–strain curve, whereas the flow stress–strain curvewas obtained from the regression of the stress–strain curve of a nano-copper thin filmtension test simulation.In addition, the chip atoms within the diamond space were moved along the tool surfaceusing a mathematical method. Also, this study introduced a new concept: ‘a combinedMorse potential function and rigid tool space restrictions criterion as the chip separationcriterion’ for the nano-scale cutting model.