Hypersonic vehicle thermal protection system model optimization and validation with vibration tests

Damage detection for thermal protection systems is crucial for hypersonic flight. Since fastener failure is a critical failure mode for many thermal protection systems, an efficient methodology that does not require a significant amount of experimental data collection and analysis for implementation is desired. In a coming paper, we develop a methodology for localizing fastener failure in a thermal protection system utilizing an experimentally validated finite element model. This paper focuses on validating the finite element model in its healthy state versus low-frequency experimental results obtained on the composite structure for future research in damage quantification. The experimental validation is implemented in three steps to individually account for the unknown composite material properties, insulation effects, and the assembly with the connecting brackets and backing structure. The inverse optimization problem implemented in the first level of experimental validation demonstrated excellent agreement between the finite element model and the experimental results. The overall assembly also demonstrated good agreement between the low-frequency dynamics of the experimental results and the finite element model. The validated finite element-model will then be used to simulate damage in the structure to investigate the effectiveness of vibration mode-based damage detection metrics.