Extending the Theory of Creep to Viscoplasticity

Abstract

A viscoplastic theory is developed that reduces to creep theory analytically under steady-state conditions. A fairly simple model is constructed from this theoretical framework by defining material functions that have close ties to the physics of inelasticity; consequently, the model is characterized easily. The computational characteristics of the model are enhanced, in general, by converting the kinetics equation from a hyperbolic relationship to a power-law relationship. The resulting model is applied to copper and to the copper alloy, NARloy Z.