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.
维普
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