Permanent set of the Space Shuttle Thermal Protection System Reinforced Carbon–Carbon material

The objective of this paper is to provide an interpretation and understanding of the permanent set (or deformation) phenomenon observed from debris impacts on Space Shuttle Thermal Protection System (TPS) Reinforced Carbon–Carbon (RCC) panels. Deflection test results for static and dynamic loadings of RCC material will be presented. Permanent set has been observed for both the static and dynamic loading onto RCC material, even for cases where no damage was detected using conventional Non-Destructive Evaluation (NDE) techniques. Although, the RCC material is considered to be brittle, the evidence of permanent set indicates a tough-brittle material behavior with plasticity. The post-test observation of permanent set, without NDE-detectable damage, indicates an opportunity for an alternative method for assessing debris impacts.