Carbon-Carbon Composite Manufacturing Process Variability and Impact on Flight Performance

The survivability, structural integrity, and control authority of hypersonic vehicles depend on the reliability of the material system used in nose cones, aeroshell, control surfaces, thermal protection system, and exhaust system. Carbon-carbon ceramic matrix composites (C/C CMCs) offer several advantages for such high-temperature applications including higher strength, higher thermal shock resistance, longer fatigue life, and reduced weight compared to other aerospace materials. While selected configurations of C/C composites and architectures have been well characterized to date, there are clear gaps in our understanding of the impact of process and/or supplier variability on the resulting material and eventual flight performance. This limits the ability of vehicle designers to determine safety margins or to effectively evaluate flight profiles. Additionally, there is a strong need to develop software tools to complement fabrication and experimental characterization for cost-effective material development.  CFD Research is teaming with Battelle to address this challenge. The team will first implement and validate an industrial (coupon to component) scale C/C process model to predict the effects of process variables, starting materials, and their structure on the as-fabricated bulk composite properties. The process model will be capable of predicting bulk mechanical and thermal properties and defect (particularly porosity) distribution on the part scale. Process models resolving the fiber tow topology will be used to inform the component level model, support verification and validation, and to provide higher resolution distributions of defects to peridynamics-based multiphysics simulations of the composite performance in relevant environments. This direct tie-in between process and performance models will enable sensitivity analyses of processing variables and investigation of parameter excursions (such as due to source material variability) on performance. Battelle will provide access to relevant databases of C/C processing parameters, resulting microstructure, and corresponding properties. Battelle will also perform experimental composite fabrication and characterization, assist in algorithm design for the model, and perform microscale (fiber resolved) simulations to support impregnation model parameterization. During the Option period, the team will establish and demonstrate a workflow linking the process model and peridynamics prediction of performance and degradation to fast-running hypersonic vehicle flight simulations of thermo-mechanical performance.