燃料组件定位格架冲击屈曲仿真分析方法与屈曲行为研究  

Study on Impact Buckling Simulation Analysis Method and Buckling Behavior of Fuel Assembly Spacer Grid

作　　者：刘胜 李朋洲[1] 杨翊仁[2] Liu Sheng;Li Pengzhou;Yang Yiren(Nuclear Power Institute of China,Chengdu,610213,China;School of Mechanics and Aerospace Engineering,Southwest Jiaotong University,Chengdu,610031,China)

机构地区：[1]中国核动力研究设计院,成都610213 [2]西南交通大学力学与航空航天学院,成都610031

出　　处：《核动力工程》2024年第3期161-169,共9页Nuclear Power Engineering

摘　　要：燃料组件定位格架作为反应堆堆芯的重要部件,其动态屈曲行为直接关系着反应堆结构的安全。本文建立了燃料组件定位格架多次重复冲击仿真分析方法,对比了单次简单冲击仿真、多次重复冲击仿真结果与试验结果的差异,讨论了仿真分析方法对格架冲击动态屈曲行为的影响。研究发现:多次重复冲击仿真分析方法能够模拟试验重复冲击的累积变形过程,其仿真结果与试验结果吻合更好;多次重复冲击仿真和试验的冲击力-冲击初速度曲线在屈曲点附近形成屈服平台,屈服平台内回弹系数和冲击动刚度维持稳定,屈服平台后冲击力快速下降,同时回弹速度与回弹系数剧烈变化,单次简单冲击仿真的冲击力和回弹速度在屈曲点后维持稳定并缓慢增长;屈曲前,冲击加速度时程曲线具有近似对称特征,随着冲击初速度的增加,冲击回弹阶段出现“拖尾”,加速度曲线对称性破坏;多次重复冲击仿真和试验的格架屈曲变形表现为以底部横向剪切变形为主的一阶屈曲破坏,单次简单冲击仿真无法准确预测屈曲形态。本文提出的多次重复冲击仿真分析方法能建立更准确的分析模型,并更准确地揭示定位格架屈曲试验中的动态力学行为。The fuel assembly spacer grid is a key part of the nuclear reactor and its dynamic buckling behaviors are important to the reactor structural safety.In this paper,the repeated impact simulation analysis method is established for the fuel assembly spacer grid,the differences between the simulation results of single impact and repeated impact and the test results are compared,and the influence of the simulation analysis method on the dynamic buckling behavior of grid impact is discussed.It is found that the simulation analysis method of repeated impact can simulate the cumulative deformation process of repeated impact in the test,and its simulation results are in better agreement with the test results.The impact force-initial velocity curves of the repeated impact simulation and the test form a yield platform near the buckling point,and the rebound coefficient and impact dynamic stiffness in the yield platform remain stable.After the yield platform,the impact force rapidly decreases,while the rebound velocity and rebound coefficient undergo drastic changes.However,the impact force and rebound velocity of the single simple impact simulation remain stable and slowly increase after the buckling point.Before buckling,the time history curve of the impact acceleration is approximately symmetrical;as the initial velocity increases,the rebound stage of the acceleration curve tails and makes its symmetry destroyed.The buckling deformation of the grids in the repeated impact simulation and the test is a first-order buckling failure dominated by transverse shear deformation at the bottom,while the buckling shape cannot be accurately predicted by the single simple impact simulation.The repeated impact simulation analysis method proposed in this paper can establish a more accurate analysis model and reveal the dynamic mechanical behavior in the buckling test of spacer grid more accurately.

关 键 词：定位格架 冲击屈曲 重复冲击 冲击力 回弹系数 冲击动刚度 

分 类 号：TL352[核科学技术—核技术及应用]