Structural components operating at elevated temperatures, such as pressure vessels and pipelines in nuclear power plants and chemical plants, experience creep, a phenomenon where materials undergo slow plastic deformation under stress and high temperature. Creep can degrade component performance, leading to failure and potentially causing severe safety accidents. Therefore, creep reliability assessment of high-temperature structural components is crucial to ensure the long-term safe operation of systems.
Methods
Finite Element Analysis: A three-dimensional finite element model of a typical structural component (pressure vessel with nozzle) was established, and elastic-plastic creep finite element analysis was conducted using ABAQUS software. Multi-source Uncertainty: Uncertainties in material parameters, geometric parameters, and loading conditions were considered, and stochastic finite element analysis was performed using the Monte Carlo simulation method. Representative Stress: The Huddleston representative stress model was employed to evaluate the effect of multiaxial stress states, and the Feltham equation was used to describe the time-dependent characteristic of representative stress. Creep Life Calculation: The linear damage accumulation rule was used to calculate the creep life of the structural component, considering the stress relaxation process of the representative stress. Reliability Assessment: The load-life interference method was used for creep reliability calculation, considering the potential shift of the maximum representative stress at the node during the creep stage. Sensitivity Analysis: The Sobol and Morris global methods were employed to conduct sensitivity analyses of material parameters on creep reliability assessment results.
Highlights
A framework for creep reliability assessment of high-temperature structural components is proposed, incorporating the time-dependent characteristic of representative stress (stress relaxation) and considering uncertainties in material parameters, geometric parameters, and loading conditions, leading to more reliable assessments. For the same creep design life, the component exhibits a higher failure probability when the time-dependent feature of representative stress (stress relaxation) is considered. This implies that conventional assessment methods that neglect stress relaxation may underestimate the risk of failure. Parameters D and d in the creep rupture life equation (relationship between creep rupture time and stress ) have more significant effects on creep rupture life than other parameters.
Authors
Prof. Fu-Zhen Xuan is currently the President of East China University of Science and Technology. He is a recipient of the National Science Fund for Distinguished Young Scholars and the Chang Jiang Scholars Program. He has also been awarded the first and second prizes of the National Science and Technology Progress Award. He has long been dedicated to research in the fields of mechanical strength and intelligent sensing, focusing on ensuring the safety of special equipment. His research interests cover structural failure analysis, life prediction, and intelligent detection, providing technical support for equipment safety operation and intelligent manufacturing.
Editor: Dr. Jun-Jing He
