Limit Load Analysis of Pressure Structures Containing Pitting Defects Subjected to High Temperature Creep

Abstract

High-temperature technologies are widely used in many industries and the high temperature components are usually designed for long term operation. Creep damages are inevitable in service, which may lead to the loss of material strength. Volumetric defects such as pits may occur during the manufacturing process and during service. These defects may cause severe reduction of the limit load of structures. The existing assessment procedures do not take into account the effect of plasticity-damage due to creep, which may lead to inaccurate assessment results. This paper aims to investigate the limit load of pressurized components with volumetric defect subjected to high temperature creep. An elasto-plastic constitutive model with coupled plasticity-damage due to creep effects is proposed. The limit load of high temperature structures with volumetric defects is systematically studied using finite element method. Safety assessment approach for structures considering plasticity-damage due to creep effect is subsequently proposed based on the principle of “fitness for service”.