Cracking characteristics of a habitable module pressure wall following orbital debris penetration

All long-duration spacecraft in low-earth-orbit are subject to high speed impacts by meteoroids and pieces of orbital debris. The threat of damage from such impacts is a significant design consideration in the development of long duration earth-orbiting spacecraft. This report presents the results of a study whose objective was to develop an empirical model to predict the magnitude of the various cracking and through-hole creation phenomena accompanying a habitable module penetration. The significance of the work performed is that the model predictions can be fed directly into a survivability analysis to determine whether or not module unzipping would occur under a specific set of impact conditions. The likelihood of module unzipping over a structure's lifetime can also be determined in such an analysis. In addition, effective hole size predictions can be used as part of a survivability analysis to determine the time available for module evacuation prior to the onset of incapacitation due to air loss. Some of the phenomena considered include maximum petal length, maximum tip-to-tip crack distance, depth of petal deformation, number of cracks formed, orientation of the maximum tip-to-tip distance with respect to the inner wall grain direction, and the effective inner wall hole diameter.