On the thermo-mechanical theory of field dislocations in transient heterogeneous temperature fields

Sur la théorie thermo-mécanique des dislocations représentées en continu dans des champs de températures hétérogènes transitoires

Manas Vijay Upadhyay (1)

1 LMS - Laboratoire de mécanique des solides

A strong coupling between the field theory of dislocation mechanics and heat conduction is proposed. The novel model, called the thermal field dislocation mechanics (T-FDM) model, is designed to study the dynamics of dislocations during rapid or gradual temperature changes in a body having a heterogeneous temperature distribution; for example, such conditions occur in a heat-affected crystalline solid during an additive manufacturing process. It is based on the principles of rational thermodynamics whose main assumptions include respecting local thermodynamic equilibrium and imposing the classical Clausius-Kelvin-Planck formulation of the second law of thermodynamics. The T-FDM model is designed to operate at the length scale of individual dislocations and temperature-dependent crystallographic dislocation driving forces are derived based on global dissipation considerations. The advantages and consequences of the assumptions of the T-FDM model under rapidly changing temperatures, both spatially and temporally, are discussed. Local thermodynamic equilibrium is found to be a reasonable assumption even for high rates of change of temperature such as those occurring during an additive manufacturing process. Highlights  Strong temperature gradients during 3D-printing can trigger dislocation dynamics  A novel fully-coupled dislocation dynamics and heat conduction model is proposed  Proposed model can deal with high temperature rates during additive manufacturing  Local thermodynamic equilibrium is respected even under strong temperature rates

Mots clés: dislocations; dynamics; thermal stress; constitutive behavior; additive manufacturing

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des solides [physics.class-ph]

Manas Vijay Upadhyay. On the thermo-mechanical theory of field dislocations in transient heterogeneous temperature fields. 2020. ⟨hal-02439503v2⟩