A 3D-Numerical Thermomechanical Approach for Materials Cutting

Abstract

Materials cutting during machining is an extremely complex thermo-mechanical problem due to the severe physical conditions associated to materials cutting mechanisms : very high elasto-viscoplastic strains and strain rates; material passes from room temperature to the heated state in milliseconds, with the heat coming from internal dissipation and friction. Based on continuum thermomechanics and including friction and large deformations in dynamics with viscoplasticity, a materials cutting three-dimensional numerical model is briefly described. Weak forms of conservation laws are introduced in an Arbitrary Lagrangian Eulerian configuration allowing for an arbitrary surface of separation of the material, and an automatic and continuous rezoning. The Coulomb friction law is introduced to model the tool-chip and workpiece-tool contacts, and heat generation and heat transfer at these interfaces are taken into account. The flow stress including temperature and strain rate effects is based on the Johnson-Cook law proposed for high strain rate conditions. A three-dimensional example is shown when simulating the oblique cutting. Finally, some needs for the future are detailed to improve constitutive laws as well as friction, and to include more physics, for example chemical diffusion in workpiece and tool.