Defining Relations of Transient Creep Under Complex Stress State

Abstract

The problem of evaluating the strength and service life of operating properties of critical engineering facilities which are characterized by multivariable non-stationary thermomechanical effects, leading to degradation of initial strength properties of structural materials (metals and alloys) on the mechanisms of fatigue and creep is considered. A mathematical model describing the processes of unsteady creep of metals under complex stress state is constructed. A theoretical-experimental method of determining the material parameters and scalar functions defining transient creep ratios is developed. The results of numerical modeling of the creep process 304 at block thermocyclic complex modes of deformation are presented. The numerical results are compared with those of full-scale experiments. Particular attention is paid to issues of simulation of creep for complex deformation processes, accompanied by the rotation of the main sites of stress and strain tensors and creep strains.

On accounting for tempering effect in unsteady creep model for metals

“…General considerations of the nonstationary creep equations [17][18][19] are: -Initially isotropic media are considered.…”

“…A mathematical model of the nonstationary creep of metals under a multiaxial stressed state was developed in [17][18][19]. In [19], reliability estimation was carried out and the boundaries of applicability of the developed defining relations of nonstationary creep under multiaxial stress state were determined.…”

“…In [19], reliability estimation was carried out and the boundaries of applicability of the developed defining relations of nonstationary creep under multiaxial stress state were determined. Applicability boundaries of the developed defining relations of nonstationary creep under multiaxial stress state were determined as well as reliability estimation was done in [19].…”