Inelastic Heat Fraction

The heat flux per unit volume, $r^{p l}$ , due to inelastic deformation is computed using the equation

r^{p l} = η σ : {\dot{ε}}^{p l}

where

η

is the constant factor you define,

σ

is the stress, and

{\dot{ε}}^{p l}

is the rate of plastic straining.

For the case when the nonlinear isotropic/kinematic hardening model the formula for the generated heat flux is

r^{p l} = η (σ - α) : {\dot{ε}}^{p l}

where

α

is the back stress.

Inelastic heat fractions are typically used in the simulation of high-speed manufacturing processes involving large amounts of inelastic strain, where the heating of the material caused by its deformation significantly influences temperature-dependent material properties. The generated heat is treated as a volumetric heat flux source term in the heat balance equation.

An inelastic heat fraction can be specified for materials with plastic behavior that use the von Mises or Hill yield surface. It cannot be used with the combined isotropic/kinematic hardening model (see Plastic Options).

An inelastic heat fraction can also be specified for material definitions that include time-domain linear viscoelasticity (see Viscoelasticity ) and time-domain nonlinear viscoelasticity, except in an explicit analysis for large-strain linear viscoelasticity. For large-strain linear viscoelasticity in an implicit analysis, the energy dissipation is computed only approximately. Hence, the fraction of the dissipated energy converted into heat can be computed only approximately.

If you do not include the inelastic heat fraction behavior in the material definition, the heat generated by inelastic deformation is not included in the analysis.


Type	Description
Inelastic Heat Fraction	$0 \leq η \leq 1$ .