Research On Similarity Criteria Of Dynamic Response Of Accident-Resistant Container Under Axial Drop Condition

Collision,drop,fire are the most typical accidental scenarios of nuclear material transportation.Under these circumstances,nuclear materials will face harsh force and thermal load conditions,and the danger to personnel and the environment in the event of a radioactive material leak will be enormous.To reduce the risk of these accidents,the application of accident-resistant container for transportation is necessary.However,to ensure an accident-resistant container has good cushioning and thermal insulation properties,it is generally necessary to perform buffering and heat insulation experiments.Due to its large mass and size,trying to determine the viability of a solution entirely through prototype testing is often costly and lengthy.The similarity theory is a scientific method that generalizes the results of individual physical phenomena(models)to this type of similar physical phenomena(prototypes).Model test is to establish a relationship between the model and the prototype to meet the similarity requirements,and predict the response of the prototype through the response of the model under specific conditions.The method can avoid the huge test investment,long period,limited test environment and security risk of large scale prototype projects,which can be used in many rounds of multi-state,multi-condition repeated tests,as one of the technical ways to solve the current engineering problems.The purpose of this paper is to find the similarity criteria for the design of accident-resistant container model in axial drop case at low speed,and to establish the design method of predicting the accident-resistant ability of the accident-resistant container prototype through the impact load in similar situations.The accident-resistant container is simplified as a two-dimensional dynamic model,and the drop impact model is solved analytically.Then the dimensional analysis is carried out to determine the three similarity criteria for the container design.On this basis,the corresponding similar design conditions are established.The displacement response of the prototype and the similar model under the corresponding drop conditions are calculated,and the similarity criteria are used to evaluate the equivalence of the responses of the model and the prototype,and satisfactory results are obtained.The stresses at the bottom center and radius of the inner container of accident-resistant container are taken as an index to characterize its impact resistance,and the main physical quantities influencing stress are found out.Based on dimensional analysis,a dimensionless relation between prototype and model stresses is established and the corresponding completely similar design criteria and distorted model design criteria are also established.Afterwards,the prototype and the model are numerically simulated under the case of drop impact.The analysis results show that the stress response of the scaled similar model has a high degree of similarity with the prototype response based on the completely similar design criterion.However,the stress response of the established distorted model has a certain regular deviation from the response of the prototype,so a speed correction index is introduced to correct the distorted model reasonably.The stress responses of distorted model and prototype can have better similarity after the correction.