Implementation and validation of creep model based on normalized parameters

In order to numerically simulate creep behaviors and stress relaxation effects of realistic structural components under operating conditions in service, a model based on normalized parameters, which can be used to describe all the features of creep deformation in three stages, was presented and coded into a users subroutine under the platform of a commercial finite element package by use of its user programmable features tools. The difference between the numerical results from the coded subroutine and the experimental data, and the effect of time step on numerical results, was investigated. The computers time consuming for solution of finite element models in different scale was compared and analyzed. For a loading case with stress and/or temperature changing, the time hardening theory and the strain hardening theory, as well as the relative time hardening theory presented with its result between those of them, were implemented in the coded subroutine. Numerical results of a plate with a hole show that the coded subroutine can be used to simulate the creep behaviors and effects of stress relaxation in realistic structural components, and that the feasibility and effectiveness of the coded subroutine are validated.