Design of experiment to measure water migration through honeycomb core on untied airlines 767s

摘要

A study was conducted using two United Airlines 767s to investigate the mechanisms of water migration through various types of honeycomb cores. Simulated hail damage was not observed to cause damage propagation in aluminum and Korex honeycomb materials. This was attributed to the ability of the cores to localize the impact damage. In Nomex and glass fiber cores a different damage propagation mechanism was observed. In these cores, the damage was not confined to the localized area around the impact. This increased core damage allowed the core to retain water. The retained water helped propagate the impact damage through a freeze thaw mechanism. Speed-tape repairs were only found to be statistically significant when water migrated through the core. Filling the honeycomb core with foam was shown to be an effective method for minimizing the damaging effects of water ingression. Slotting and draining the core also offered some relief from water accumulation in the core, but foaming damaged core was established as the most effective technique.