変位制御弾塑性疲労条件下のき裂構造の破壊力学パラメータの推定

Abstract

Quantitative prediction of crack growth under displacement-controlled conditions such as thermal fatigue is a key to the residual life prediction of plant components. In a previous paper, the authors proposed a simplified prediction method of fracture mechanics parameters such as J and C* of a perforated plate under thermal fatigue, on the basis of the reference stress approach under displacement-controlled conditions. In this paper, the fracture mechanics parameters of a CCT specimen and structural models of CrMoV cast steel under displacement-controlled conditions were experimentally and numerically examined on the basis of the proposed method. The ratio of the inelastic and the elastic crack opening displacement, as well as the ratio of the inelastic and the elastic load point displacement, was used to correlate the fracture mechanics parameters in the inelastic and elastic regions. The proposed method based on displacements was found to be insensitive to a small variation in the predicted macroscopic load in comparison with the original reference stress method, and is considered to be applicable to displacement-controlled conditions such as thermal fatigue.