Analytical Research On Impacting Load Of Aircraft Crashing Upon A Concrete Target

In this paper,the stress-wave theory is used to study the impact load characteristics of the aircraft impact on the nuclear reactor containment.After analysis of the Riera equation,which is also the most widly used impact equation in this field,it is found that in the original Riera equation,aircraft is considerd as rigid plastic body.Based on this assumption,the aircraft damaged area growth rate is equal to the speed of complete part of the aircraft.This assumption is questionable that speed of crushing process must equal to the speed of impact at any time during the impact process which can not be seen in the unfilterd impact load of the expereiment.On the basis of the previw analysis,a new impact load equation which based on stress-wave method is put forward,and the damage speed of the aircraft is extended,and an explicit analytical expression is proposed.The difference between the stady target and moving target upon the entire time and impact force is discussed in this paper.A new model and a new method of numerical calculation are proposed after an analysis of speed of plastic wave and impact speed.The numerical results calculated by the new impact loading equation are in good coordination with the previous experimental results.And it is found that there is few different between the numerical results of expicit equation and recursive eqution if the speed of the uncrushed part of the aircraft changes slowly.The explict equation can be used to simplify the procees of calculation.In addition,it is found that the modified coefficient of the modified Riera impact load equation has a clear physical meaning,namely,the ratio of generalized plastic wave velocity at the impact interface to the velocity of the remaining unbroken aircraft.Therefore,considering the influence of plastic wave propagation velocity on impact load is an effective method to modify the impact load equation.Although in the current conditions,taking into account the material is not the single material,and the structure is also complex,plastic wave propagation speed is very difficult to directly determine,but considering the correction of that is an effective method for improving the impact load equation.