Session: 03-08-02: Micromechanics and Multiscale Modeling

Paper Number: 137561

137561 - Microstructure-Sensitive Study of Effective Mechanical and Thermal Properties of Fiberform Materials 

Thermal protection system (TPS) is an essential component of space vehicles for protection against aerothermal heating during the atmospheric entry. Depending on the entry environment, different types of TPS are needed. Entry into planet atmospheres with extreme environments, such as Mars or Saturn, requires an ablative TPS that withstand high heating rates by absorbing heat through ablation. Several types of ablative TPS have been flown on NASA missions, including superlight ablators (SLA), phenolic impregnated carbon ablator (PICA), and AVCOAT. Among these ablative TPS, PICA is currently the workhorse of TPS materials for NASA because it is the lightest weight ablator capable of withstanding entry at Earth, Mars, and Titan.

The fabrication of PICA begins with the procurement of rayon. The rayon is carbonized and cast into a rigid block called FiberForm. The FiberForm is then infused with a low-density aerogel of phenolic resin that serves as the ablative material during reentry. Due to the critical applications of PICA in aerospace reentry industry, extensive study can be found in the literature regarding its surrogate material, the FiberForm. Understanding the thermal and mechanical performance of FiberForm plays critical role in design and application of the material for NASA current and future missions.

FiberForm material is fibrous and porous. As a result, its physical properties are microstructure sensitive. Therefore, large microstructure-based analysis is needed to better understand the mechanical and thermal performance of FiberForm. In this work, the effective mechanical and thermal properties of FiberForm are determined using computational tool via the standard mechanics approach. Differing sizes of microstructures obtained from X-ray computed tomography are used to explore the microstructure-sensitive properties. Statistical analysis is used to understand the microstructure size dependent mechanical and thermal properties.

Presenting Author: Donglai Liu University of Kentucky

Presenting Author Biography: Donglai Liu is a Ph.D. candidate at the University of Kentucky. His research topic is computational solid mechanics focused on mesh free-methods.