Precision guided projectiles (PGPs) experience severe shock loads during launch emanating from the propellant gases inside the barrel and the surrounding air. The complex flow environment that exists within the confined space of the barrel and at muzzle exit is greatly influenced by the supersonic speed of the projectile, the compressibility of the air, and the rapid state transition of the projectile from the confined volume of the barrel to the surrounding free-space. In our earlier efforts (X. W. Yin, P. Verberne and S. A. Meguid, Multiphysics modelling of the coupled behaviour of precision-guided projectiles subjected to intense shock loads, Int. J. Mech. Mater. Des. 10 (2014) 439–450; P. Verberne and S. A. Meguid, The coupled behaviour of precision-guided projectiles subject to propellant induced shock loads using multiphysics analysis, in 8th Int. Conf. Mech. Mater. Des. (2019); P. Verberne and S. A. Meguid, Dynamics of precision guided projectile launch: Fluid-structure interaction, Acta Mech. (2020)) examined the fluid–solid interaction problem. In this paper, we expand our earlier effort by examining the underlying mechanisms associated with the solid–solid interaction between the projectile and the barrel walls that severely govern the survivability of the embedded electronic systems (EES). This was achieved by conducting comprehensive finite element (FE) simulations of the dynamics of the entire launch process of a projectile accounting for the intense combustion pressures of the propellant, the large accelerations experienced during the launch and the induced shock waves. Our FE simulations successfully capture the interaction of the projectile with the barrel. Our work reveals that frictional forces due to contact inside the barrel significantly affect the projectile’s acceleration response at muzzle exit. Immediately following muzzle exit, the rapid reduction of the frictional forces inside the barrel results in a rapid increase of the projectile acceleration followed by a rapid reduction due to the free expansion of the propellant gases and air drag, leading to large acceleration fluctuations.

中文翻译：

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精确制导弹丸发射动力学：固-固相互作用

精确制导弹丸 (PGP) 在发射过程中会承受来自枪管内的推进剂气体和周围空气的严重冲击载荷。弹丸的超音速、空气的可压缩性以及弹丸从枪管的密闭空间到枪口的快速状态转变等因素对炮筒有限空间内和炮口出口处存在的复杂流动环境影响很大。周围的自由空间。在我们早期的工作中（XW Yin、P. Verberne 和 SA Meguid，多物理场对承受强烈冲击载荷的精确制导炮弹的耦合行为进行建模，Int. J. Mech. Mater. Des. 10 (2014) 439–450； P. Verberne 和 SA Meguid，使用多物理场分析的受推进剂引起的冲击载荷影响的精确制导炮弹的耦合行为，在第八国际。会议。机甲。母校。德斯。（2019）；P. Verberne 和 SA Meguid，精确制导弹丸发射动力学：流固耦合，Acta Mech。(2020)) 研究了流固相互作用问题。在本文中，我们通过研究与弹丸和枪管壁之间的固固相互作用相关的潜在机制来扩展我们早期的工作，这些机制严重控制了嵌入式电子系统 (EES) 的生存能力。这是通过对弹丸的整个发射过程的动力学进行全面的有限元 (FE) 模拟来实现的，该模拟考虑了推进剂的强烈燃烧压力、发射过程中经历的大加速度和诱发的冲击波。我们的有限元模拟成功地捕捉到了弹丸与枪管的相互作用。我们的工作表明，由于枪管内的接触而产生的摩擦力会显着影响炮弹在枪口出口处的加速响应。在炮口退出后，枪管内摩擦力的迅速降低导致弹丸加速度迅速增加，随后由于推进剂气体和空气阻力的自由膨胀而迅速降低，从而导致较大的加速度波动。