スエリングとクリープの遷移挙動を考慮した照射下クリープ構成式

Abstract

Elaboration of the constitutive equations of creep and creep damage under irradiation for structural analyses in multiaxial states of stress is discussed. In order to formulate the continuous transition of swelling after the incubation period of neutron irradiation, the curvature parameter proposed by Bates et al. was introduced into the evolution equation of swelling. The constitutive equation of irradiation-enhanced creep, furthermore, was elaborated by taking account of the physical mechanisms of the flux-and fluence-dependence of dislocation behavior. As regards the transient creep, on the other hand, the creep law of McVetty type and Kachanov-Rabotnov creep-damage theory were modified to describe the irradiation-enhanced creep. The irradiation-induced creep was formulated by incorporating the SIPA (Stress-Induced Preferential Absorption) mechanism. Finally unirradiated creep, post-irradiation creep, and in-reactor creep of type 316 stainless steel at elevated temperatures were predicted by the elaborated constitutive equations. The validity of the equations was discussed by comparing the predictions with those of the corresponding experiments.