Constraint characterization and fracture initiation analysis for semi-elliptical surface cracks in reactor pressure vessel. (April 2023)

• Record Type: Journal Article
• Authors: Zheng, Y.; Wang, G.Z.; Tu, S.T.; Xuan, F.Z.
• Is Part Of: International journal of pressure vessels and piping. Volume 202(2023)
• Publication Date: 2023-04
• Subjects: Constraint characterization -- Crack -- Reactor pressure vessel -- Unified constraint parameter -- Fracture initiation -- Finite element analysis; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2023.104910
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: The constraint and fracture initiation for semi-elliptical surface cracks in an actual large scale reactor pressure vessel (RPV) have been investigated by finite element analysis. The results show that the overall constraint level of the cracks increases when the crack depth a / t increases and crack aspect ratio a / c decreases. For most cracks with a / t = 0.25–0.8 and a / c = 0.2–2, the constraint level is higher than the standard plane strain specimen, and the conventional fracture assessment may possibly yield non-conservatism. The aspect ratio a / c has obvious effects on the distributions of the new unified constraint parameters A d * and the elastic-plastic stress intensity factor K J and the fracture initiation position along the crack fronts. For low aspect ratio cracks with a / c < 1.0, fracture initiation probably appears in the deepest region of the crack. For high aspect ratio cracks with a / c ≥ 1.0, fracture initiation is likely to occur in the near-surface region. To improve the accuracy of fracture assessment for cracks in the RPV, the constraint effect requires to be incorporated. The engineering estimation methods of the parameters A d * and K J at the crack initiation positions have been provided and verified. Highlights: The constraint and fracture initiation for cracks in reactor pressure vessel have been studied. The constraint increases when crack depth a / t increases and crack aspect ratio a / c decreases. Crack aspect ratio a / c has obvious effect on fracture initiation position along the crack fronts. Constraint effect requires to be incorporated in fracture assessment of reactor pressure vessel. Engineering estimation methods of constraint and fracture parameters have been provided.