FEM analysis on three dimensional cutting: analysis on large deformation problem of tool entry

Tool entry process in three dimensional cutting is simulated by finite element method. Since the chip forming process is one of large deformation problems, geometrical nonlinearity due to the change of shape is introduced into finite element formulation. Constant strain tetrahedra element is used and over-constraint of incompressibility on the deformation of the finite elements in plastic region is relaxed using Nagategaal-Rice functional to make the elements as deformable as real continuum. The chip formation from tool entry to steady state is realized in the analysis and stress and strain distributions in chip and machined surfaces are also obtained. Lower shear angle at side surface of the work, side flow and chip flow direction predicted are in good agreement with experimental results of cutting of plasticine.