超高速撞击中的弹丸形状效应数值模拟研究

文章用AUTODYN仿真软件对球形、圆锥形、圆柱形和盘形4种不同形状弹丸超高速撞击Whipple防护结构所产生的碎片云形貌特征及对后墙的毁伤程度进行了数值仿真研究。对比分析结果指出:质量与速度相等的4种不同形状弹丸撞击缓冲屏所产生的碎片云有明显差异;弹丸长径比越小,穿过缓冲屏后的破碎程度越大;在5 km/s撞击速度下,球形弹丸对后墙的毁伤程度最小,而圆柱形弹丸的毁伤程度最大。这说明弹丸的形状对超高速撞击结果有显著影响,在航天器超高速撞击风险评估和防护工程设计中应充分考虑弹丸的形状效应。球形弹丸的弹道极限曲线在防护结构的碎片防护能力评价时存在高估的问题,在实际工作中要特别注意这一点。

A numerical simulation of projectile shape effects on hypervelocity impacts

The projectile shape effects on hypervelocity impact are qualitatively and quantitatively investigated in terms of the characteristics of debris clouds and the damage of the rear wall for the typical Whipple shield, by using AUTODYN hydrocodes to simulate numerically the Whipple shield impacted by the spherical, conical, cylindrical and disk projectiles, respectively. The comparisons of the numerical simulation results between these projectiles show that the debris clouds characteristics of the buffer impacted by projectiles of 4 different shapes with the same mass and the same impact velocity are obviously different. The extent of the projectile breaking into fragments increases with the decrease of the aspect ratio. The spherical and the cylindrical projectiles give the least and the most damage to the rear wall at 5 km/s, respectively. It indicates that the projectile shapes have remarkable effects on the hypervelocity impact results, and these effects should be considered in the hypervelocity impact risk assessment and the protection design for spacecrafts. When the spherical projectile-based ballistic limit curves are used to evaluate the debris protection capability of shield, an overestimation will be made, which should be paid attention to in practice.