航天器舷窗玻璃超高速撞击损伤与M/OD撞击风险评估

用北京卫星环境工程研究所的18mm口径二级轻气炮(TLGG)和20 J激光驱动微小飞片装置(LDFF-20)对用作航天器舷窗玻璃的熔融石英玻璃的超高速撞击损伤特性进行了实验研究和分析.其中,TLGG发射的球形铝弹丸直径分别为1 mm和3 mm,速度2～6.5 km/s;LDFF-20发射的圆柱形飞片厚度7 μm,直径1 mm,速度1～8.3 km/s.撞击结果为:对12 mm厚的熔融石英玻璃,直径为3mm的弹丸甚至在2.8 km/s的低速下就将其穿透,而直径为1 mm的弹丸在6.5km/s的高速下没有穿透,这说明弹丸直径对撞击损伤特性有很强的影响;LDFF-20发射的微小飞片的撞击仅在玻璃表面产生很浅的凹坑,没有裂纹产生,但微小飞片的累积撞击损伤明显地降低了玻璃的透光性.实验初步获得了侵彻深度PC、侵彻直径D1与弹丸撞击速度Vp、弹丸质量Mp之间的经验关系.依据实验结果和目前的微流星体/空间碎片(M/OD)环境工程模型,建议对于高度为400 km、轨道倾角42°、寿命为3年的典型航天器,其舷窗玻璃的临界安全(非穿透)厚度至少为12mm.

Hypervelocity impact damage of fused silica glass and M/OD impact risk assessment of spacecraft windshield

Hypervelocity impact experiments were conducted on fused silica glass to obtain the damage characteristics and to build a damage model using Ly12 aluminum spheres of diameters 1 mm and 3 mm launched by the two-stage-light-gas gun of up to 6.5 km/s, and the small aluminum flyer of 1 mm in diameter and 7 μm in thickness launched by a laser-driven flyer facility of up to 8.3 km/s, developed by Beijing Institute of Spacecraft Environment (BISEE). The empirical damage equations were obtained to approximately predict the penetration depth (PC) and its diameter (D1) as a function of impact parameters (projectile velocityVp, mass Mp). For the Ly12 A1 projectile of 3 mm diameter sphere, the glass was perforated thoroughly even at a low impact velocity of 2.80 km/s. This means that the projectile diameter plays a major role with respect to the impact damage. The damage feature for the laser-driven small flyer is quite different, and only a shallow pit is formed in the glass surface. But the accumulative damage effects on the glass surface reduce the transmittance significantly. With the M/OD environment, it is suggested that the critical safety thickness (without perforation) of fused silica glass outer windshield is taken as 12 mm for a 400 km altitude orbit space station of 3 year's life time.