Research On Energy Release Time And Damage Effect Of Energy-containing Fragments

Energy-containing fragment,also known as active fragment,is a new type of damage element which combines multi-functional energetic structural materials with prefabricated fragments.In addition to kinetic energy damage of inert fragments,energy-containing fragments can also cause deflagration reaction behind the target,causing damage to the target behind the target.At present,there are many researches on post-damage of energy-containing fragments,but relatively few researches on impact energy release time of energy-containing fragments.In this paper,Ni/Al based energetic material is taken as the research object.Theoretical analysis,numerical simulation and experimental research are combined to study the energy release time and damage effect of energy-containing fragments.Firstly,the impact damage mechanism of energy-containing fragments was analyzed,and the process of energy-containing fragments was divided into the stages of impact initiation,target penetration,debris cloud flight and deexplosion reaction.The theory of impact temperature rise of energy-containing fragments is also expounded.Secondly,Ni/Al based energetic materials of A,B and C formulations were prepared by metal powder metallurgy.The mass ratios of Al/Ni/Mg were A（34Wt%,65Wt%,1Wt%）,B（19Wt%,80Wt%,1Wt%）and C（47Wt%,52Wt%,1Wt%）,respectively.The optimum sintering temperature of energetic material with A and B formula is 380℃,and that of energetic material with C formula is 450℃.The reaction temperatures of energetic materials A and B were obtained by baking and burning experiments.XRD analysis showed that the reaction products of energetic materials A and B were mainly Al Ni and Al Ni₃.Dynamic compressive mechanical properties of Al/Ni/Mg energetic materials were analyzed by Hopkinson bar experiment.Finally,according to the theoretical calculation,it is found that the energy release time can be changed by changing the thickness of the energetic fragment head.On this basis,LS-DYNA simulation software is used to study the penetration of energy-containing fragments into aluminum targets.The simulation results show that the aspect ratio of energy-containing fragments is between 0.8 and 1.1,which is more conducive to kinetic energy damage and deflation damage.The deflagration rate of energy-containing fragments is related to the initial velocity.The larger the initial velocity is,the larger the debris cloud area behind the target is,and the higher the deflagration rate of energy-containing fragments is.When the initial velocity of energy-containing fragments is greater than 1000m/s,the deflation rate of energy-containing fragments is greater than 90%.The simulation of penetrating aluminum target with energy-containing fragments with head thickness of 1～4mm shows that the initial reaction time of the fragment with head thickness of 4mm is 10us longer than that of the fragment with head thickness of 1mm.When the fragment initial velocity is 1000 m/s,the head thickness is 3mm,the residual velocity behind the target is642m/s,the deflation rate of the energy material contained in the fragment is 60%,and the comprehensive damage effect is the best.