Hypervelocity impact of space debris on multiple composite bumpers: Experiments & simulations using LS-DYNA

This paper describes the superiority of carbon/epoxy double bumpers with standoff distance incorporation over single bumpers, which can be used for the spacecraft shielding as a shift towards flexible shielding system. In this research, initially carbon/epoxy CU125NS prepreg was used to manufacture with having stacking sequence of [(0/±45/90)₂]s in 16 layers, due to their superiority over other commercially available prepregs. Afterwards the specimens were exposed to low Earth orbit environment, where they were attacked with UV, AO, thermal cycling and high vacuum conditions. The last factor of space debris impact was tested by using light gas gun with the Al2017-T4 projectile having mass of 0.25 g within the velocity range of 1500±500 m/s. The total mass loss of 0.42% was found on average for the composites when exposed to LEO environment. It was also being found that the double bumpers in combination of normal and oblique configurations can effectively encounter the space debris impacts in comparison to single bumpers either in normal or oblique configuration. Because the oblique impact events represent 80∼90% of actual space debris impacts which a spacecraft experiences during its lifespan. The specific energy absorption for double bumper in normal and oblique configurations with 100 mm standoff distance was found on average 14%, 35% and 50% higher in comparison to that of single bumpers at 45°, 30° and 0° respectively. In the end LS-DYNA analyses were also done by using SPH module for the double bumpers. The average energy difference of 15∼22% was found while comparing with the experimental results. The simulated results helped to understand the space debris impact event and it's propagation in a quite effective way.