Shakedown and creep rupture analysis of printed circuit heat exchangers based on the linear matching method framework

In the field of nuclear engineering, Printed Circuit Heat Exchangers (PCHEs) have become increasingly popular and the structural integrity assessment of these key power plant components is crucial. As part of the structural integrity assessment, creep rupture analysis considers the interaction of cyclic plasticity and creep behaviour, which is vital for components subjected to cyclic thermal-mechanical loads. The Linear Matching Method (LMM) framework has included a creep rupture module based on an extended shakedown algorithm, which has been adopted by several researchers. However, the current LMM framework mainly relies on linear extrapolation and requires users to provide a large amount of data points to estimate the rupture stress. This paper introduces a Unified Creep Rupture Equation (UCRE) for characterizing the creep rupture curves of diverse steel types. The UCRE is implemented in an extended shakedown algorithm and integrated into the LMM framework. The numerical method is validated through a comparative analysis, wherein the estimated rupture curves are compared with those provided in the ECCC data sheet, as well as against alternative numerical models. Shakedown and creep rupture analyses are then performed on a PCHE core. The proposed method facilitates the parametric study of changing materials and the process of material selection. Various geometric configurations are also considered and the proposed unitary cell model is verified by comparing the results with ones from full FE models. The UCRE has been proved to be an accurate engineering tool for the prediction of rupture strengths while the LMM framework has gained improved usability and versatility for engineering applications.