A First-Principles-Based Model for Crack Formation in a Pressurized Tank Following an MMOD Impact

Most robotic spacecraft have at least one pressurized vessel on board, usually a liquid propellant tank. One of the design considerations of such spacecraft is the anticipation and mitigation of the possible damage that might occur from on-orbit impacts by micro-meteoroids or orbital debris (MMOD). While considerable effort has been expended in the study of the response of non-pressurized spacecraft components to MMOD impacts, relatively few studies have been conducted on the pressurized elements of such spacecraft. In particular, since it was first proposed nearly 45 years ago, NASA\u27s current evaluation methodology for determining impact-induced failure of pressurized tanks has undergone little scrutiny. This paper presents a first-principles based model that has been developed to predict whether or not cracking might start or a through-crack might be created under an impact crater in a thin plate. This model was used to examine the effect of penetration depth on crack formation and whether or not the crack might grow through the tank wall thickness. The predictions of the model are compared to experimental data with encouraging results. The paper also develops some suggestions for future work in this area, including the extension of the first-principles model to include 3-D crack initiation modelling