HYPERVELOCITY IMPACT ON SPACECRAFT CARBON-FIBER-REINFORCED PLASTIC ALUMINIUM HONEYCOMB/

Samples of a spacecraft primary external wall structure, as used in a low earth orbit remote sensing platform, have been tested to determine the response to the hypervelocity impact and ballistic limit (for mm- sized impactors) of the 47 mm thick structure at 5 km/s. A strong depe ndence of the ballistic limit on projectile density was identified. Th is programme was carried out using the two-stage light gas gun at the University of Kent at Canterbury. The equivalent diameters of the fron t and rear holes for each impact were analysed as a function of the im pactor parameters. Damage equations derived by other experimenters wer e compared to the experimental results. X-ray non-destructive testing was used to determine the level of internal honeycomb damage for a sam ple. The dependence of the witness plate damage (placed behind the tar get to capture any ejecta from the rear surface) on the impactor param eters was recorded. It was found that the use of 'equivalent thickness es' of aluminium may not be appropriate as a general conversion factor for carbon fibre reinforced plastic (CFRP) facesheets. A simple damag e equation is presented, based on the total hole size as a function of the impact energy. The ballistic limit cannot be defined solely in te rms of impact energy and shows an additional dependence with projectil e density. The amount and type of ejecta produced is a strong function of density and a less strong function of projectile diameter, and its production cannot be linked with the rear hole diameter.