SAMPE Journal - March/April 2024 - 3

GUEST EDITORIAL
Joseph H. Koo
The University of Texas at Austin,
Walker Department of Mechanical
Engineering, Austin, TX
Email: jkoo@mail.utexas.edu
Samantha Bernstein
The University of Texas at Austin,
Walker Department of Mechanical
Engineering, Austin, TX
Preface: Material Systems for Hypersonic Flight: Materials, Material Response Modeling,
and Aerothermal Ground Testing
In this special issue of the SAMPE Journal, we are focusing on " Material Systems for Hypersonic Flight: Materials,
Material Response Modeling, and Aerothermal Ground Testing. " Hypersonic technology has the potential
to revolutionize the travel, defense, and space exploration sectors and has garnered significant attention
worldwide from scientists, engineers, and policy makers. One of the major challenges facing hypersonic
technology is the extreme environments generated by traveling at more than five times the speed of sound,
i.e., > Mach 5!
In this issue, we explore the innovative methods being used to develop and study materials for these extreme
conditions. Two articles focus on developing new thermal protection systems (TPS) materials for hypersonic
applications. The other two articles describe characterization, testing, and numerical modeling of TPS materials.
This issue therefore provides an overview of the forefront of materials development, characterization, and
aerothermal ground testing research at top facilities across the globe.
Yancey et al. describe unique oxidized PAN fibers, HEXTOW® 85 fibers, ceramic-converted carbon fibers,
carbon-carbon matrix systems, and other advanced systems developed at Hexcel. These material systems are
designed for non-ablating carbon-carbon composites for hypersonic TPS applications.
El Rassi et al. provide an overview of the hypersonic, high-temperature activities at the von Karman Institute
for Fluid Dynamics' (VKI) Plasmatron facility, including the three recently developed supersonic nozzles using
additively manufactured aluminum alloy. They also characterize the nozzle flow, compare it with simulations,
and delve into recent material test cases conducted at VKI using these nozzle configurations.
Koo et al. present their unique approach to developing, characterizing, and modeling novel TPS materials
using " process-properties-performance " relationships at the University of Texas at Austin and KAI, LLC. The
five integrated steps are demonstrated: (a) Processing and fabrication of medium- and low-density, and duallayer
ablatives, (b) Characterization of the thermal and flammability properties of neat resin systems and TPS
materials initially, later characterize the physical, mechanical, and thermophysical properties of the virgin and
char TPS materials required for numerical modeling in step (e), (c) aerothermal ground testing using .oxyacetylene
test bed (OTB) with advanced diagnostics and Hypersonic Materials Environmental Test System
(HYMETS) arc jet test facilities at NASA Langley Research Center, (d) microstructures characterization and
modeling using scanning electron microscopy (SEM) and synchrotron hard X-ray micro-computed tomography
at Lawrence Berkeley National Laboratory/Advanced Light Source, and the NASA Porous Microstructure
Analysis (PuMA) software to calculate material properties, and (e) numerical modeling of material response of
TPS materials.
Picazo et al. use machine learning technique to accelerate the process of characterizing and optimizing
the pyrolysis reactions of high-temperature composites at the University of Washington. Gaussian Process
Regression (GRP) is used to determine optimal test parameters to accurately characterize pyrolysis kinetics to
achieve desired yield. This unique approach can be used to improve high-temperature composites processing
efficiency with minimal experimental efforts.
As we navigate this exciting frontier in flight and materials, we must prioritize sharing our insights, innovations,
and discoveries with the greater advanced materials and processing community. Sharing knowledge and
experience with experts in other fields is the best way to enrich our own work. With that in mind, please enjoy
this special issue of the SAMPE Journal.
www. sampe.org
MARCH APRIL 2024
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SAMPE Journal - March/April 2024

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