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extend the life of an aircraft from
“ If20wetocan40 years,
we’re saving lives and money
and reducing maintenance costs. In space,
it’s even more critical, where repairs aren’t
an option. - DR. SAMIT ROY
”
“We use those simulations to train a reduced-order
machine learning model,” Roy said. “If trained well, it can
run in minutes instead of hours, and we can put it on board
the unmanned aerial vehicle or spacecraft.”
This reduced-order model acts like an onboard
diagnostic system. Once damage is detected, the AI
estimates the size and location and compares it to failure
thresholds. If the 昀氀aw is too close to the danger zone,
the system triggers a third module: repair.
This rapid feedback loop is crucial for UAVs and
spacecraft, where the stakes are high and intervention is
often impossible.
“Some missiles and payload cameras are important,
and if they are collecting data and monitoring hostile
countries’ data continuously, we cannot lose those UAVs,”
Mulani said. “We need to keep those active and always
bring them back, even if they are damaged. We can apply
this immediately.”
The system is highly adaptive in that the same sensors
that detected the damage now serve as actuators. They
produce high-frequency vibrations that generate heat,
and that heat causes the healing to happen.
“The self-healing part is, in some ways, less complicated,”
Roy said. “We’re healing carbon composites, which are
stiff and brittle. They delaminate internally, and that
damage is hard to see; therefore, it’s hard to repair.”
Members of Roy’s lab embed thermoplastic particles
into the epoxy resin used in composites. Thermoplastics
are like high-tech waxes; they melt at a certain
temperature. “When we vibrate the composite using our
sensors as actuators, it creates heat,” Roy said. “That heat
melts the thermoplastics, which 昀氀ow into the crack. Then
we stop the vibration, it cools and the crack is sealed. The
vibration helps by generating both heat and 昀氀ow, so it’s
doing two things at once. Especially in space, where the
cooling is very rapid, this process is ideal.”
This process is automatic, reversible and repeatable.
“We’re the only group I know of that’s combining all three
modules into one integrated system,” Roy said. “Others
have worked on individual parts, especially self-healing,
but not as a complete autonomous loop. Some systems
are one-time use, using microcapsules that break when
damaged. Ours is rehealable. We’ve tested up to seven
healing cycles at the same spot.”
The healing module has also passed a major milestone:
repairing damage under load. Structures are rarely
stress-free when failure begins. Roy’s team successfully
demonstrated healing in a loaded composite panel.
With the technology proven in lab settings, the next
step was to test it in extreme environments.
“We tested this at the NASA Marshall Space Flight
Center under cryogenic vacuum conditions,” Roy said.
“No funds were exchanged, but they let us use their lab.
It shows this works at minus 40 degrees Celsius in
high vacuum.”
NASA’s interest is no surprise. Damage in space is not
hypothetical; micrometeorite impacts and thermal cycling
pose constant threats.
“We carried out some of the experimentation at NASA,
so those people were testing because these components
will operate in deep space,” Mulani said. “We tested in
that similar environment.”
Though still in the research phase, the technology
is already showing promise.
In the short term, the military could apply it to UAVs
operating in remote or hostile environments, allowing
them to complete missions even with minor structural
damage. Longer term, the system could be adapted for
manned aircraft, spacecraft and satellites. “Our goal is to
ultimately create a system which is sustainable,” Mulani
said. “It will reduce waste because you are prolonging the
component’s life and reutilizing the same thing again and
again. The terms of investment are a little better.”
The team has 昀椀led a provisional patent and is
looking for more funding to reach a prototype level.
Roy remains inspired by his students and by viewing
the concept anatomically.
“Seeing bright, motivated graduate students excited
about something that could have major societal impact—
like self-healing structures—that keeps me going,”
Roy said.
Roy would also eventually like to create a center of
excellence for intelligent self-healing systems.
“This research brings together a wide range of
disciplines: materials science, AI, aerospace, structural
engineering and chemistry,” Roy said.
This project is the perfect example of interdisciplinary
innovation and greatly affects the future of self-healing
technology, sustainability and the longevity of
our machines.
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