Composite Material Characterization using Microfocus X-ray Computed Tomography Image-based Finite Element Modeling

This study utilized microfocus X-ray computed tomography slice sets to model and characterize the damage locations and sizes in thermal protection system materials that underwent impact testing. Image processing-based software was used to visualize and process the slice sets, followed by mesh generation on the segmented volumetric rendering. Then, the local stress fields around several of the damaged regions were calculated for realistic mission profiles that subjected the sample to extreme temperature and other severe environmental conditions. The resulting stress fields were used to quantify damage severity and make an assessment as to whether damage that did not penetrate to the base material could still result in catastrophic failure of the structure. It is expected that this study will demonstrate that finite element modeling based on an accurate 3D rendered model from a series of computed tomography slices is an essential tool to quantify the internal macroscopic discontinuities and damage of a complex system made out of thermal protection material. Results were obtained showing details of segmented images; 3D volume rendered models, finite element meshes generated, and the resulting thermomechanical stress state due to impact loading for the material are presented and discussed. Further, this study was conducted to exhibit certain high-caliber capabilities that the nondestructive testing group at National Aeronautics and Space Administration Glenn Research Center can offer to assist in assessing the structural durability of such highly specialized materials so improvements in their performance and capacities to handle harsh operating conditions can be made.