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接管是核压力容器的一种重要结构形式,在内压作用下接管内壁角裂纹应力强度因子K_1是规范要求的对该部位作断裂评定的重要依据。用改进的1/4边中节点三维20节点等参奇异元和位移法计算了球接管内壁角裂纹的应力强度因子K_1及其变化分布规律,分析了K_1与裂纹及结构的几何参数关系。所得结果和三维光弹性冻结切片法试验分析结果十分吻合。进一步计算分析了柱接管内壁角裂纹应力强度因子K_1及其与裂纹和结构几何参数关系。在计算分析的基础上所得出的计算核压力容器接管内壁角裂纹在内压作用下的应力强度因子K_1的近似公式简单而又偏保守,且为三维光弹试验所证实,可供工程参考使用。
The takeover is an important structural form of nuclear pressure vessel. The stress intensity factor K1 of the corner crack taken by the internal pressure under the internal pressure is an important basis for the evaluation of the site for fracture assessment. The stress intensity factor K_1 and its variation distribution of the corner cracks in the inner wall of the ball joint were calculated by using the improved three-dimensional mid-point three-dimensional 20-node isoparametric singular and the displacement method. The relationship between K_1 and the geometric parameters of the crack and structure was analyzed. The results obtained are in good agreement with the experimental results of the three-dimensional photoelastic freezing slice method. The stress intensity factor K_1 of corner crack and the relationship between the stress intensity factor and the geometric parameters of crack and structure are further analyzed and calculated. On the basis of the calculation and analysis, the approximate formula for calculating the stress intensity factor K_1 under the internal pressure of the inner wall of a nuclear pressure vessel taken over by the nuclear pressure vessel is simple and conservative, and is confirmed by the 3D photoelastic test and can be used for engineering reference .