Damage Of Concrete Target Induced By Reactive Segmented Kinetic Rods

The proportion of using precision-guided weapons in wars is increasing and the weapons are more and more powerful and precise.Important goals have been transferred into ground.Penetration weapons which can invade and destroy underground fortifications become research focus at home and abroad.To improve the power of the penetration weapons,based on the active material,the inert long rod and the segmented rod warhead,this paper proposes a new warhead concept which is composed of inert pellets and active projectile.And on this basis,combined with experimental research,numerical calculation and theoretical analysis,the terminal effects were studied.57mm caliber light gas gun and 50 mm diameter wave lens loading platform were used to investigate responses of PTFE/AL specimens under different plane wave impact loading.Lagrangian analysis method was used to analyze pressure-time history curve of four gauging points,and the state of stress-specific volume behind shock wave front were obtained.Consulting the theoretical calculation of Hugoniot curve,the state of the reaction degree was inferred by “approach method”,then the different pressure of reaction degree was obtained.The impact induced thermochemistry model which is controlled by the impact temperature is verified by experiment.the reaction pressure after the shock wave front of PTFE/AL under a certain intensity impact was obtained by the model.Shock wave velocity of the status was calculated.Under intensive impact,the impact reaction after a wave front was complete,which reflected PTFE/AL had similar detonation reaction characteristics.Damage effect of single kinetic energy bar penetrating into concrete target experimental research was carried out.Through the comparative study of damage effect of single active kinetic energy rod and single inert kinetic energy rod into concrete target,the general process and characteristics of explosive coupling damage effect of single active kinetic energy rod penetration was proposed,and high efficiency of the damage mode was validated.Damage effect experiments of combined kinetic energy rods into concrete target with pre-drilled cavity were carried out,including single kinetic energy bar,"inert rod before active rod" and "inert rod after active rod”.General interaction process of active segment rod and concrete target was obtained indirectly,and the enhanced effect of damage and damage increase mechanism were verified,thus the damage mechanism was revealed.The experimental results showed that kinetic energy rod’s penetration ability enhanced obviously based on preliminary target body damage,and its penetration depth increased by 22%-37%.Penetration depth of unit mass active rod was larger than that of inert rod: increased by 22.2%-41.5% at the same speed.According to similar detonation reaction characteristics of PTFE/AL under shock loading,this thesis chose Lee-Tarver model to describe the impact response characteristics,and combined with the characteristics of PTFE/AL that cannot self-sustainingly react,transformed Lee-Tarver model from "ignition,growth,complete" trinomial form into two type forms of “ignition,growth”.Based on AUTODYN fluid dynamics software platform,the numerical calculation model of damage of active segment rod into concrete target was establish.Numerical model was established by ballistic experiment data,and the appropriate algorithm and material model parameters were determined.By the method of numerical simulation,different material,different length-to-diameter ratio of inert rod was studied.The results showed that within the scope of the study,1.5 length-to-diameter ratio of the tungsten alloy rod got deeper penetration depth and certain radius cavity,which is a better choice for inertia part of active segment kinetic energy rod.Compared concrete target damage effect with the same quality and speed of active segment rod,inert segment rod and inert long rod of,through the analysis of the corresponding penetration depth,damage depth and damage features,damage mechanism of penetration efficiency enhanced by the active segment bar was presented.The damage effects of different active part mass fraction in active segment rod were studied.Penetration depth was increased with the increasing mass fraction to a point and then decreased.The relatively optimal value was 0.1 in the scope of this study.The structure of active segment kinetic energy rod was discussed.Compared with no shell and an aluminous shell,a certain thickness of the steel shell was more advantageous to the active segment rod penetration damage of concrete target.And 1.5 length-to-diameter ratio of active segment bars is better.