COMPUTATIONAL MACHINING OF TITANIUM-ALLOY - FINITE-ELEMENT MODELING AND A FEW RESULTS

A finite element modeling was developed for the computational machinin g of titanium alloy Ti-6Al-4V. The chip formation in metal cutting is one of the large deformation problems, thus, in the formulation of the elastic-plastic deformation analysis, geometrical nonlinearity dice t o the large shape change of the finite elements was taken into account and the over-constraint of incompressibility on the deformation of or dinary finite elements in the plastic range was relaxed to make the el ements deformable as a real continuum. A ductile fracture criterion on the basis of strain, strain rate, hydrostatic pressure and temperatur e was applied to the crack growth during the chip segmentation. The te mperature field in the flowing chip and workpiece and the fixed tool w as calculated simultaneously by an unsteady state thermal conduction a nalysis and the remeshing of tool elements. The serrated chips predict ed by the computational machining showed striking resemblances in the shape and irregular pitch of those obtained by actual cutting. The mea n cutting forces and the amplitude of cutting force vibration in the c omputational machining were in good agreement with those in the actual machining.