Theoretical and numerical investigations on the headspace of cartridge cases considering axial deformation and movement

The cartridge case headspace is the axial clearance between the cartridge and bolt of an automatic weapon, and influences the reliability and security of the weapon. Accordingly, theoretical and numerical studies were conducted to analyze the dynamic response of cartridge cases during internal impact considering the initial radial clearances between the cartridge case and chamber. A theoretical model was proposed to predict the cartridge case headspace considering both the deformation and movement of the cartridge case and confirmed by the results of nonlinear finite element simulations. The differences between the results of the conventional static model and the dynamic model were then comprehensively evaluated. The effects of the angle between the cartridge and chamber, the cartridge case material, and the internal impact pressure on the predicted headspace value were also analyzed. The dynamic response of the cartridge case predicted by the dynamic model was more accurate than that predicted by the conventional static model. The internal impact pressure, pressure change rate, and cartridge material were all found to affect the predicted headspace.     

高频地波超视距雷达述评

高频(HF)地波超视距雷达(GW-OTHR)利用雷达波束绕地表面衍射作用,能探测视距外的舰船、低空飞机和巡航导弹,不仅覆盖面积大、费用低,能弥补常规微波雷达低空盲区和天波超视距雷达的近距盲区,也无需注意电离层的变化,且可反隐身、抗反辐射导弹(ARM),因而在许多国家的国民经济和国防领域中得到了广泛的应用。论述了地波沿海面传播的特性和探测能力,并对超视距雷达的发展和应用进行了介绍。