Application of Modern Approaches to the Numerical Modeling of the Stress-Strain State for the Strength Assessment of Complex Units of the NPP Primary Circuit Equipment. Part 3. Application of Submodeling Technique and Extended Finite Element Method for Calculation of the Reactor Pressure Vessel Nozzle Zone

IF 0.7 4区 材料科学 Q4 MATERIALS SCIENCE, CHARACTERIZATION & TESTING
E. O. Kondryakov, V. V. Kharchenko
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Abstract

Recent studies have shown that nozzle zones are one of the most dangerous elements of the reactor vessel. High stresses in such nodes can lead to the appearance of angular cracks. At the same time, the issue of choosing the critical dimensions and direction of crack location from the point of view of calculations for resistance to brittle fracture remains open. The paper presents the results of numerical modeling of the stress-strain state of the nozzle zone of the reactor vessel by the classical finite element method (FEM) and the extended finite element method (XFEM) using the submodeling technique. The results of numerical modeling by the classical FEM for the mode of hydraulic testing of the reactor vessel pressure vessel nozzle zone with three types of cracks are presented: surface, subweld, and a crack with 1 mm penetration into the weld. For twelve types of cracks with variations in their size and direction of location in the reactor vessel pressure vessel nozzle zone, the results of calculations of resistance to brittle fracture by the XFEM method for one of the characteristic modes of thermal shock are presented. The calculation results proved that axial cracks are more dangerous than circular cracks of the same dimensions. Cracks with a semi-axis ratios a/c = 0.3 and a/c = 0.7 are more dangerous for the axial and circumferential directions, respectively. At the same time, cracks with a/c = 0.3 are more sensitive to the direction of location than cracks with a/c = 0.7. It was shown that the use of the XFEM method makes it possible to conduct a rapid assessment of the resistance to brittle fracture with the possibility of varying the shape, size, and location of the crack, which allows one to effectively determine its critical size and the most dangerous location in the structural element.

Abstract Image

应用现代方法建立应力-应变状态数值模型,评估核电站一次回路设备复杂单元的强度。第 3 部分.应用子建模技术和扩展有限元法计算反应堆压力容器喷嘴区
最近的研究表明,喷嘴区是反应堆容器中最危险的部分之一。这些节点上的高应力会导致角裂纹的出现。与此同时,从计算抗脆性断裂的角度来看,如何选择临界尺寸和裂纹位置方向的问题仍然悬而未决。本文介绍了采用经典有限元法(FEM)和子模型技术的扩展有限元法(XFEM)对反应堆容器喷嘴区的应力应变状态进行数值建模的结果。本文介绍了采用经典有限元法对反应堆压力容器喷嘴区的水压试验模式进行数值建模的结果,包括三种类型的裂纹:表面裂纹、焊缝下裂纹和渗入焊缝 1 毫米的裂纹。对于反应堆压力容器喷嘴区内尺寸和位置方向不同的 12 种裂纹,采用 XFEM 方法对其中一种热冲击特征模式的脆性断裂阻力进行了计算,并给出了计算结果。计算结果证明,轴向裂纹比相同尺寸的圆形裂纹更危险。半轴比 a/c = 0.3 和 a/c = 0.7 的裂缝分别对轴向和圆周方向更危险。同时,与 a/c = 0.7 的裂缝相比,a/c = 0.3 的裂缝对位置方向更为敏感。研究表明,使用 XFEM 方法可以快速评估脆性断裂的抗力,并可改变裂缝的形状、尺寸和位置,从而有效确定裂缝的临界尺寸和结构元件中最危险的位置。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Strength of Materials
Strength of Materials MATERIALS SCIENCE, CHARACTERIZATION & TESTING-
CiteScore
1.20
自引率
14.30%
发文量
89
审稿时长
6-12 weeks
期刊介绍: Strength of Materials focuses on the strength of materials and structural components subjected to different types of force and thermal loadings, the limiting strength criteria of structures, and the theory of strength of structures. Consideration is given to actual operating conditions, problems of crack resistance and theories of failure, the theory of oscillations of real mechanical systems, and calculations of the stress-strain state of structural components.
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