Ultimate Bearing Capacity Analysis and Sizing Optimization of a Cracked Reactor Pressure Vessel in the Coupled Thermo-Mechanical Field
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Pressurized thermal shock (PTS) can subject a crack surface to a very high tensile stress. Also the material toughness is obviously decreased in the cooling process, so it is necessary to study the influence of PTS on the ultimate bearing capacity of a reactor pressure vessel with defects. A 3-D finite element model is established for the beltline region around an inner crack. The FEM is used to reveal the transient temperature field and stress field, and the XFEM is adopted to simulate the ductile crack propagation. To ensure that the strength requirement is satisfied, the ultimate internal pressures of vessels with different crack sizes and different wall thicknesses are obtained. The result shows that the ultimate bearing capacity of the base wall with shallow surface cracks at high temperature is mainly controlled by tensile strength, while it is also affected by the fracture toughness of the material under the severe PTS. The stress in the early stage of the PTS is mainly the thermal stress, and later is the thermo-mechanical coupling stress. The impact of the crack depth on the bearing capacity of the structure is much greater than that of the crack length.
KeywordsPressurized thermal shock Reactor pressure vessel Ultimate bearing capacity XFEM
This study was funded by National Natural Science Foundation of China. Author Guozhong Chai has received research grants from National Science Foundation Committee (Grant Number 51275471). Author Yumei Bao has received research grants from National Science Foundation Committee (Grant Number 51105339). The authors declare that they have no conflict of interest. Furthermore, the authors are grateful for the technical support of the Key Laboratory of Special Purpose Equipment and Advanced Processing Technology of Ministry of Education.
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