Correlation Analysis of Established Creep Failure Models through Computational Modelling for SS-304 Material

Abstract

To maintain safety and reliability in power plants, creep-life prediction models have received much attention over the years. This article was designed to focus on the conditions when a material structure is exposed to extremely high temperatures and pressures with the help of finite element analysis. A direct comparison of the feasibility of different models’ fitness and suitability in predicting creep damage was presented in this article by simulating the damage evolution of a uniaxial SS-304 specimen under a pre-defined load, using established constitutive creep models. Comparative assessments of minimum creep strain rate, creep deformation, and stress rupture were demonstrated using the Norton–Bailey (NB), Kachanov–Rabotnov (KR), Theta projection (TP), and sine-hyperbolic (SH) models while standardizing them with the Omega model. The FE results of a dog-bone specimen, while implementing the models, were compared with the actual creep experiment results to check for the models’ reliability and validation. Subsequently, sensitivity studies of the established creep models were conducted using the statistical tools RSM and ANOVA, with an analysis of how the parameters for operation, design, and material dependency came into effect. Thus, quantitative and qualitative correlation analyses of the FE creep response for these five established models were conducted together, resulting in finalizing the selection of the most suitable model, the sine-hyperbolic model, for the SS-304 material under the defined boundary conditions. The 0.84 R2 value of the sine-hyperbolic model proved the model’s selection for predicting the creep response of stainless steel 304. The method can be applied to select a suitable creep damage model as per the feasibility of the operating conditions.

New Creep Crack Growth Prediction Model for the Life Assessment of Stainless-Steel Material Using Computational Modeling

“…where, ∆t is the change in time, ∆ε ∆t is the rate of change in uniaxial deviatoric creep strain increment represented as DECRA(1) in the creep user subroutine [43]. Differentiation of Equation ( 9) with respect to stress gives Equation (10):…”

“…These models used some assumptions in the analysis, which caused limitations in accurately predicting the creep deformation and remaining life of engineering components [9]. The current state-of-the-art of creep deformation prediction is mostly based on five established models, which include Norton-Bailey, Kachanov-Rabotnov, Omega, Theta projection, and Sine hyperbolic models [10]. Each model has its own limitations and is found to work only in specific environments and loading conditions [11].…”