Research On Scaling Law Of Typical Structure On Strain Rate Effect

Large-scale prototype experiment under impact load such as projectile penetration process will cost a lot of time and money,and also needs corresponding experimental equipments.Therefore,people began to use the dimensional analysis method to predict the behavior of prototype experiment with the help of model experiment.However,for the experiment under impact load,the model experiment is difficult to simulate the mechanical behavior of the prototype experiment due to the strain rate effect such as the structural response of critical device of the projectile under high speed penetration environment.Because of the strain rate effect the model experiment will reflect stronger results,which coulde lead to dangerous design.Therefore,it is of great significance to study the scale law of dynamic response of typical structure under high speed and high strain rate.In order to solve the problem of scaling effect in the scaling law of dynamic response of typical structures under high speed and high strain rate,theoretical analysis,numerical simulation and experimental verification method are proposed.Aiming at the phenomenon that the free beam structure is not similar in deformation between model experiment and prototype experiment due to the strain rate effect,a velocity correction theory is proposed to reduce the response deviation.The main work and conclusions are as follows:(1)The influence of strain rate effect on the scaling law of structural response under impact loading is discussed by means of dimensional analysis method.A new dimensionless analysis method based on collision mass,velocity and stress is proposed.A velocity correction method is obtained to reduce the deformation dissimilarity due to the strain rate effect,and the non-geometric scaling law with strain rate effect is considered.(2)The reverse ballistic Taylor impact experiment is taken as the research object.The influence of the scale parameter and the strain rate control parameter c on the deformation of the model experiment and the prototype experiment is analyzed by the numerical simulation.The validity of the velocity correction method for the free beam subjected to axial load and the adaptability of the correction theory to different strain rate materials are verified.The free beam subjected to transverse load experiment is taken as the research object.The influence of the scale parameter on the deformation of the model experiment and the prototype experiment is analyzed by the numerical simulation.The validity of the velocity correction method for the free beam subjected to transverse load is verified.The object which the velocity correction method can apply on is expanded(3)Based on gas gun experimental platform,the reverse ballistic Taylor impact prototype experiment,model experiment and correction model experiment are performed.The DIC method is used to analyze the stress wave propagation law and the deformation mode.It is proved that there is certain scale effect in the reverse ballistic Taylor impact experiment.With the analysis of the final deformation of the sample,the result shows that the correction method can effectively decrease structure response between prototype and model due to strain rate effects in the reverse Taylor impact experiment.