Study On The Factors Affecting Shaped Energy Jet Oblique Penetration Into Thin Layer Charge Reactive Armor

Explosive reactive armor has the advantages of light weight,low cost,high anti-projectile efficiency,convenient loading and unloading,and good safety performance.It is widely used in the protection of armored vehicles at home and abroad.The basic structure of explosive reactive armor is the "sandwich" type flat charge structure,the thickness of the charge layer is generally 3～8 mm,which is easy to cause collateral damage to the vehicle body and accompanying personnel after detonation.In this paper,the detonation energy is effectively controlled by reducing the thickness of the charge layer,so as to reduce the collateral damage effect.In this paper,the interaction process between shaped charge jet and thin-layer charge structure is studied mainly from the influence factors such as normal Angle,charge thickness,backplane thickness,etc.,and the simulation calculation and analysis are carried out on jet penetration reaction armor penetration state,pressure value and reactivity of observation point,pressure cloud map of sandwich explosive,jet morphology and after-effect target penetration results.The results show that:(1)The detonation diffraction phenomenon occurs in the sandwich explosive during the oblique penetration of the thin reactive armor by jet,which directly affects the initiation process and protective performance of the reactive armor.The fitting relation between the normal Angle and the shape of the detonation wave front is given,and the diffraction law of the normal Angle on the wave front is obtained: as the normal Angle increases,the positions of the short diameter and the short diameter change in the initial detonation wave front shape.When the long diameter is in the x axis and the short diameter is in the y axis,the whole charge layer will eventually detonate with the growth of detonation reaction.(2)If the normal Angle is fixed and the charge thickness is increased,the completion time of detonation diffraction is accelerated.There is a critical initiating charge thickness between 0.8mm-1mm.By analyzing the penetration process,the detonation mechanism of the jet oblique penetration of sandwich explosive is obtained: When shaped charge jet penetrates the panel at a certain Angle,one side of the expanding hole wall is squeezed down,while the other side is curled up,resulting in asymmetric pressure and detonation response at the observation point of the sandwich explosive.Furthermore,after detonation at the initiation point,the initial detonation wave propagates in the sandwich explosive not directly from inside to outside,but first towards the direction of jet penetration.Then,with the growth of detonation reaction,diffraction phenomenon occurs in the detonation wave,which detonates the explosive on the side opposite to the jet motion.The propagation of detonation wave in the sandwich charge has regional and temporal characteristics.(3)The thickness of the backplane has little effect on the detonation diffraction in the sandwich explosive,and mainly interferes with the escape jet.The length of the escape jet in the discontinuous interference is calculated according to the time required for the flight plate to reach the maximum velocity.In addition,the energy provided by the detonation reaction accelerates the transverse motion of the thin plate to cut the escape jet,and the jet is divided into three parts according to the interference degree of the panel and the back plane.Finally,the rationality of theoretical analysis and simulation results is verified by experiments.The results are in good agreement with the numerical simulation results,and the error is within the allowable range.The research results provide theoretical support for the interaction process between reactive armor and cumulative jet,and have reference value for the structural design of reactive armor and the improvement of armor protection mechanism.