Multi-axial creep-fatigue analysis of a cracked groove structure subjected to cyclic thermal loading

Abstract

The aim of this study is to analyze the local change in stress–strain and damage behavior in an inlet groove structure of a power plant component under the effect of the crack geometrical constraint. A robust constitutive model is used to describe the inelastic behavior of advanced 9–12% Cr heat-resistant steels at high temperature. Steam temperature and loading profiles corresponding to the idealized startup, holding and shutdown sequence of the structure are assumed. Thirteen cycles of this sequence are chosen for the loading conditions. Transient heat transfer analysis is conducted to estimate the thermal field throughout the structure. Structural analysis is then performed using the material constitutive model. The results show that the crack geometrical constraint not only changes the stress–strain behavior, but also the damage distribution. Compared to the results without the crack effect, the damage locations demonstrate a major change. Specifically, the damage starts underneath the surface of the groove structure. This is attributed to the more complex multi-axial features in the regions close to the surface of the structure.