Penetration Of Small Size Fragment Into Individual Soldier Protection Equipment

Small size fragment is one of the main development directions of individual soldier fragment warhead in the future.Carrying out relevant researches on small size fragment penetrating human body simulation target with individual soldier protective equipment to determine whether the fragment causes damage to personnel after penetrating individual soldier protective equipment,analyze the penetration process,damage failure mechanism and factors affecting the penetration performance of fragments,and establish the equivalent components of human body simulation target with individual soldier protective equipment,the energy formula and ballistic limit formula of small size fragment penetrating target,which have great reference value for the optimal design of fragment warhead and protection equipment of individual soldier.The traditional 25 mm thickness red pine target was used as human simulation target.Through the test of small tungsten sphere penetrating second level bulletproof helmet and pine target with third level soft body armor,the ballistic limit of tungsten sphere and damage failure modes of bulletproof fiber and pine target were obtained.The experimental results show that the ballistic limit of small tungsten sphere with mass of 0.21 g and 2.8 mm in diameter penetrating bulletproof helmet is 558.1 m/s.The three kinds of small tungsten spheres with mass of 0.17 g(2.6 mm in diameter),mass of 0.21 g(2.8 mm in diameter)and mass of 0.44 g(3.6 mm in diameter)can penetrate through pine target with body armor,whose ballistic limits are 742.3 m/s,692.9 m/s and 570.1 m/s respectively.The failure modes of bulletproof fiber are mainly matrix crack,fiber fracture and delamination.And there is a cross shaped damage on the fiber layer,which is matrix crack macroscopically.While shear and plug spalling are the mainly failure modes of pine target.On the basis of test,the penetration process and damage failure mechanism of tungsten sphere penetrating pine target with body armor were analyzed by numerical simulation,and the influence of thickness change of body armor and mass change of tungsten sphere on the penetration performance were studied.The results of numerical simulation show that the stress wave on the fiber layer diffuses outward around the center of the impact point in the form of a cross during the process of tungsten sphere penetrating body armor,and there is a cross shaped damage on the fiber layer,which is consistent with the experimental results.With the increase of the thickness of body armor,the energy absorption efficiency of the target increases,and the ballistic limit of tungsten sphere tends to increase linearly.And with the increase of the mass of tungsten sphere,the energy absorption efficiency of target decreases continuously,and the ballistic limit of tungsten sphere decreases in the form of power function approximately.Based on the energy equivalence principle,the equivalent relationship between pine target with body armor and LY-12 hard aluminum target was studied by experiment and numerical simulation.The results show that the ballistic limit of tungsten sphere with mass of 0.21 g and diameter of 2.8 mm penetrating 8 mm thickness LY-12 hard aluminum target is 850.1 m/s.The ballistic limits of three kinds of tungsten spheres with mass of 0.17 g(2.6 mm in diameter),mass of 0.21 g(2.8 mm in diameter)and mass of 0.44 g(3.6 mm in diameter)penetrating 6.2mm thickness LY-12 hard aluminum target are 758.7 m/s,705.2 m/s and 577.8 m/s respectively.For the penetration of tungsten sphere with mass less than 0.46 g,pine target with body armor can be equivalent to LY-12 hard aluminum target with thickness of 6.2 mm.On the basis of the above research,using the method of dimensional analysis,the energy formula of tungsten sphere penetrating pine target with body armor was established,and ballistic limit formula was deduced.The results show that the calculated values of energy formula and ballistic limit formula are in good agreement with the experimental values,which can be used to calculate the energy consumption and ballistic limit of tungsten spheres with different mass penetrating pine target with body armor respectively.