A sensitivity analysis of the finite element simulation of the high speed machining with the material rheological behaviour

Résumé

This paper deals with the influence of the rheological behaviour on the morphology and geometry of the chip during a high speed machining. In order to describe the material rheology corresponding to high strain rates, large values of cumulated plastic strain and important temperature gradients, the Split Hopkinson Pressure Bars (SHPB) experimental test is used. A general parameter identification method based on an inverse finite element analysis is used to compute rheological parameters. The idea is to find a set of the constitutive coefficients which minimizes a least-squares cost function defining the difference between the global experimental measurements and the corresponding numerical data obtained from a finite element simulation of the test. A finite element model of the high speed machining is employed to analysis the sensitivity of the numerical results in the cutting area with different rheological laws: a classical Johnson-Cook one and a proposed Arcsinushyperbolic one. This new law, proposed by the authors, shows the importance of the rheological formulation to a better description of the cutting results: distribution of equivalent strain rate, cumulated plastic strain, the equivalent Von-Mises stress, temperature and geometry of the cutting area.