Vs. Joshi et al., VISCOPLASTIC ANALYSIS OF METAL-CUTTING BY FINITE-ELEMENT METHOD, International journal of machine tools & manufacture, 34(4), 1994, pp. 553-571
Determination of the primary shear deformation zone (PSDZ) to evaluate
tool-chip interface temperature and forces during metal cutting proce
sses is important. Evaluation of the PSDZ can be performed either expe
rimentally or analytically. Experimental methods are cumbersome and ti
me-consuming. Hence, an analytical method is proposed. Metal undergoes
a large plastic deformation during cutting and behaves like an incomp
ressible, non-Newtonian fluid. The material behaviour, therefore, is m
odelled by a viscoplastic constitutive equation. Temperature effects a
re included by evaluating the material properties at a typical average
temperature usually encountered in the cutting zone. Only orthogonal
steady state machining is considered so that the problem of metal flow
in the cutting zone can be modelled as a two-dimensional, steady stat
e problem. The finite element method (FEM) is used to convert the cont
inuity and momentum equations to a set of non-linear algebraic equatio
ns that are solved by the frontal method. The results obtained for the
average shear strain rate, shear flow stress and mean width of the PS
DZ compare favourably well with the experimental results. The PSDZ is
found to depend basically on feed rate and cutting speed for a given w
orkpiece material, which is consistent with the experimental observati
ons of others. It is concluded that a 3% cut-off for the maximum strai
n invariant can be used to determine the mean width of the PSDZ.