Numerical Simulation of Anti-Penetration Performance of Body Armor against Small Tungsten Sphere

In order to study the anti-penetration performance of body armor against small tungsten sphere, combined with the experiment, the numerical model of small tungsten sphere penetrating into body armor was established by using the finite element analysis software LS-DYNA. On this basis, the penetration process was numerically simulated, the damage mechanism of body armor was analyzed, and the influence of Kevlar and Ultra-high molecular weight polyethylene (UHMWPE) hybrid ratio on the anti-penetration performance of body armor was discussed. The investigation results show that the shear failure of fiber mainly occurs on the impact face of body armor, and the tensile fracture of fiber mainly occurs on the back of body armor, accompanied by a certain delamination failure under the penetration effect of small tungsten sphere. The tensile failure and delamination failure degree of fiber decrease with the increase of the impact velocity of small tungsten sphere. Compared with the body armor made of Kevlar, the body armor with hybrid structure of Kevlar placed on the impact face and UHMWPE placed on the back has better anti-penetration performance. When the hybrid ratio of Kevlar and UHMWPE is 1∶1, 1∶2 and 1∶4, the anti-penetration performance of body armor is improved by 3.7%, 5.3% and 4.4% respectively, and the mass of body armor is reduced by 14.1%, 18.8% and 22.5% respectively. In the comprehensive consideration of anti-penetration performance and weight of body armor, the Kevlar/UHMWPE structure whose fiber hybrid ratio is 1∶2 is the best. When the impact velocity is near the ballistic limit, Kevlar/UHMWPE hybrid structure has better energy absorption effect than single Kevlar structure. However, with the increase of the impact velocity, the difference of energy absorption between them decreases gradually. The research results have a certain reference value for the optimization design of protective equipment.