破片头部系数对TNT冲击起爆临界速度影响规律研究

为研究破片头部形状在炸药冲击起爆中的影响，基于破片冲击起爆炸药的临界能量判据准则，结合LS-DYNA有限元软件，分别计算了正四棱柱破片、正六棱柱破片、圆柱破片、模拟弹丸破片（fragment-simulating projectiles，FSP）和球头形破片等5种破片冲击起爆TNT装药的理论和仿真速度阈值，并拟合出FSP冲击起爆炸药的理论头部形状系数。结果表明，在相同质量和撞击横截面积下，不同头部形状的破片撞击TNT装药的起爆阈值不等；起爆时间与破片的动能大小有关，动能越大，起爆时间越短。对于多边正棱柱类型的破片（如正四棱柱破片、正六棱柱破片、正八棱柱破片等），提出了以正棱柱的外接圆柱作为简化模型来计算多边形正棱柱破片冲击起爆TNT速度阈值，发现多边正棱柱破片横截面的边数越多，计算结果与数值模拟结果吻合越好。

Influence of Fragment Head Coefficient on the Critical Velocity of Shock Initiation of TNT

In order to study the effect of fragment head shape on the detonation of explosives, calculations using LS-DYNA finite element software based on critical energy were conducted on five types of positive four-prism, positive six-prism, cylindrical fragment, fragment simulating projectiles(FSP) and spherical head, respectively. Theoretical and simulation speed thresholds of blasting TNT, and theoretical head shape coefficient of the simulated projectile fragment were fitted. Results show that with the same mass and impact cross-sectional area, initiation threshold values of TNT are different for different head shapes. Initiation time relates to the kinetic energy of the fragment. The larger the kinetic energy, the shorter the initiation time. For multilateral positive prismatic fragments(such as positive four-prism fragments, positive hexagonal fragments, positive octagonal fragments), a simplified model was proposed to calculate TNT speed threshold by the impact of polygon positive prismatic fragments. It was found that the more sides of the cross section of the multilateral positive prismatic fragment, the better the result of numerical simulation.