Hypo-- and hyperinelasticity applied to modeling of compacted graphite iron machining simulations

Paper in proceeding, 2011

In the present paper we are concerned with constitutive modeling and validation of the thermomechanically coupled Compacted Graphite Iron (CGI) machining problem. Particular emphasis is placed on the significance of the choice of different hypoelastic-inelastic formulations in terms of four different objective stress rate formulations. We also relate to a thermodynamically consistent hyperelastic--inelastic formulation based on multiplicative decomposition of the deformation gradient. The consequently induced tangent material behavior is then derived in the spatial setting in terms of the Oldroyd stress rate, and it is compared to the hypo--formulations. The Johnson--Cook (JC) model is taken as the main prototype for the modeling of isotropic hardening, strain rate and temperature dependencies. The different models are compared in simple shear, uniaxial tensile--compressive tests, and finally in a representative CGI--machining simulation, and the resulting mechanical isothermal behavior obtained from the different ways of establishing the objective stress rate are surprisingly similar.