Influence of Whipple Shield Configuration on Hypervelocity Impact Resistance

The threat of orbital debris to space structures is well understood with efforts being made to develop superior shielding for objects operating in low Earth orbit. In traditional Whipple shield designs, the area between the front bumper and rear pressure wall, termed the standoff distance, is left empty. One of the more recent improvements in shield design has been the utilization of a honeycomb sandwich core design. In this design an initial thin bumper plate is used to fragment the projectile, followed by a honeycomb design which is implemented to further slowdown the resulting fragments in the stand-off region. In this design the rear pressure wall is subject to less damage as a result of the impact, due to the addition of the honeycomb core. Despite these improvements, it is often argued that the addition of a honey comb core within the Whipple shield induces a channeling behavior of the projectile, where the sharp edges of the honeycomb split the projectile, and the fragments generated are unable to escape the individual honeycomb core that it is propelled into. It is theorized that this channeling effect causes more damage than an impact where no honeycomb is present. This channeling effect induces a large amount of the mass of the projectile to impact the back plate over a much smaller area. As a result, the damage to the back plate is far more localized and of a higher intensity. In this paper the efficacy of this theory has been studied through an analytical approach, where Whipple shields with the honeycomb and standard 2-plate designs are subjected to hypervelocity impact.