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承压热冲击(PTS)使反应堆压力容器(RPV)的完整性面临极大的挑战,尤其是在喷嘴周围的环带区.考虑到瞬态温度处于零韧性参考温度之上,引入非线性材料性能来模拟一个真实RPV的混合温度场和应力场.应用扩展有限元法对喷嘴区中的裂纹扩展过程进行模拟,并得到了承压热冲击下的临界裂纹尺寸.结果显示,PTS初期的热应力效应显著,后期热-机械耦合作用产生的峰值应力很可能会引起结构失效.应用直接和间接耦合法得到的数值结果吻合,且后者的计算效率较高.在塑性极限承载状况下,裂纹尖端在靠近内壁的位置容易产生扩展.离内壁较远的裂纹尖端由于受热冲击影响较小,发生裂纹扩展的可能性相对较低.随着基体墙厚度的减小,容许的裂纹尺寸急剧缩小,接近临界承载状态时稳态裂纹扩展的程度明显降低.
Pressurized thermal shock (PTS) poses a significant challenge to the integrity of the reactor pressure vessel (RPV), especially around the nozzle zone. Considering that the transient temperature is above the zero-ductile reference temperature, the introduction of non-linear material Properties to simulate the mixed temperature field and stress field of a real RPV.The crack growth process in the nozzle area was simulated by the extended finite element method and the critical crack size under the confined thermal shock was obtained.The results show that the initial thermal stress The effect is significant and the peak stress caused by late thermo-mechanical coupling is likely to cause structural failure.The numerical results obtained by the direct and indirect coupling method are in good agreement, and the latter is more efficient in calculation.When the plastic limit load condition, the crack tip Near the inner wall of the easy to produce expansion.The crack tip far from the inner wall due to thermal shock less likely to crack propagation is relatively low.With the reduction of the thickness of the basement wall, the allowable crack size shrinks sharply, close to The extent of steady-state crack propagation at critical loading is significantly reduced.