Creep rupture limit analysis for engineering structures under high-temperature conditions

The efficient and accurate prediction of creep rupture limit poses a huge challenge for high-temperature engineering such as aerospace, nuclear and chemical industries. It is important to investigate the applicability of mainstream assessment approaches and related creep rupture failure mechanisms through theoretical and numerical views. In this study, major creep rupture assessment techniques are comparatively investigated for the first time, including the isochronous stress-strain (ISS) curve based creep rupture limit analysis, the Omega creep damage model based creep analysis and the direct method based creep rupture assessment by an extended Linear Matching Method (LMM). New virtual creep test curves are generated from the Omega creep model and chosen as the unified creep source data to derive the key material parameters used for different methods. For proposing a reasonable strategy for evaluating high-temperature structures in terms of creep rupture, the balance between computational efficiency and accuracy is comprehensively analyzed. Through a practical engineering application of a high-temperature pressure vessel component, a profound insight into the techniques of creep rupture evaluation is delivered from different views. Moreover, several assessment curves are built based on a new understanding of creep rupture failure mechanism, with an effective numerical plan to validate the creep rupture boundary illustrated. It is demonstrated that the LMM direct creep rupture analysis is more suitable for calculating the structural creep rupture limit, with both monotonic and cyclic load conditions considered.