Description: The Columbia Accident Investigation Board (CAIB) concluded that the cause of the tragic loss of the Space Shuttle Columbia and its crew was a breach in the thermal protection system on the leading edge of the left wing. The breach was initiated by a piece of insulating foam that separated from the left bipod ramp of the External Tank and struck the wing in the vicinity of the lower half of Reinforced Carbon-Carbon panel #8 at 81.9 seconds after launch. The CAIB conclusion launched an extensive series of studies to identify the cause of and factors influencing foam shedding and foam debris liberation. Over the last few years, it has become apparent, through various laboratory experiments and analytical studies, that voids and defects in the foam have a significant influence on foam shedding phenomena.

Research studies are currently being conducted to improve the ability to predict foam material failure and the foam shedding phenomena. Studies to improve the analysis methods for predicting the thermo-structural behavior of rigid closed-cell polymeric foams under combined thermal and mechanical loading are being pursued. Efforts are also being conducted to study the fracture mechanics behavior of these foams. The combination of improved structural analysis methods and a better understanding of the foam fracture behavior will provide Space Shuttle engineers with more accurate tools for determining the effect of voids and defects on foam stress states, stress intensity factors and the likelihood of foam failure. This symposium will report on the results of a number of these studies. Analytical, numerical and experimental studies will be presented.