New research leads to drones changing shape mid-flight

Date:
June 18, 2020
Source:
U.S. Army Research Laboratory
Summary:
Engineers have developed autonomous air vehicles that can change
shape during flight.



FULL STORY ========================================================================== Soon, the U.S. Army will be able to deploy autonomous air vehicles that
can change shape during flight, according to new research presented at
the AIAA Aviation Forum and Exposition's virtual event June 16.


========================================================================== Researchers with the U.S. Army's Combat Capabilities Development Command's
Army Research Laboratory and Texas A&M University published findings of
a two-year study in fluid-structure interaction. Their research led to a
tool, which will be able to rapidly optimize the structural configuration
for Future Vertical Lift vehicles while properly accounting for the
interaction between air and the structure.

Within the next year, this tool will be used to develop and rapidly
optimize Future Vertical Lift vehicles capable of changing shape during
flight, thereby optimizing performance of the vehicle through different
phases of flight.

"Consider an [Intelligence, Surveillance and Reconnaissance] mission where
the vehicle needs to get quickly to station, or dash, and then attempt
to stay on station for as long as possible, or loiter," said Dr. Francis Phillips, an aerospace engineer at the laboratory. "During dash segments,
short wings are desirable in order to go fast and be more maneuverable,
but for loiter segments, long wings are desirable in order to enable
low power, high endurance flight." This tool will enable the structural optimization of a vehicle capable of such morphing while accounting for
the deformation of the wings due to the fluid- structure interaction,
he said.

One concern with morphing vehicles is striking a balance between
sufficient bending stiffness and softness to enable to morphing,"
Phillips said. "If the wing bends too much, then the theoretical benefits
of the morphing could be negated and also could lead to control issues
and instabilities." Fluid-structure interaction analyses typically
require coupling between a fluid and a structural solver.



========================================================================== This, in turn, means that the computational cost for these analyses can
be very high -- in the range of about 10,000s core hours -- for a single
fluid and structural configuration.

To overcome these challenges, researchers developed a process that
decouples the fluid and structural solvers, which can reduce the
computational cost for a single run by as much as 80 percent, Phillips
said.

The analysis of additional structural configurations can also be performed without re-analyzing the fluid due to this decoupled approach, which in
turn generates additional computational cost savings, leading to multiple orders of magnitude reductions in computational cost when considering
this method within an optimization framework.

Ultimately, this means the Army could design multi-functional Future
Vertical Lift vehicles much more quickly than through the use of current techniques, he said.

For the past 20 years, there have been advances in research in morphing
aerial vehicles but what makes the Army's studies different is its look
at the fluid- structure interaction during vehicle design and structural optimization instead of designing a vehicle first and then seeing what
the fluid-structure interaction behavior will be.

"This research will have a direct impact on the ability to generate
vehicles for the future warfighter," Phillips said. "By reducing the computational cost for fluid-structure interaction analysis, structural optimization of future vertical lift vehicles can be accomplished in a
much shorter time-frame." According to Phillips, when implemented within
an optimization framework and coupled with additive manufacturing, the
future warfighter will be able to use this tool to manufacture optimized
custom air vehicles for mission specific uses.

Phillips presented this work in a paper, Uncoupled Method for Massively Parallelizable 3-D Fluid-Structure Interaction Analysis and Design,
co-authored by the laboratory's Drs. Todd Henry and John Hrynuk,
as well as Texas A&M University's Trent White, William Scholten and
Dr. Darren Hartl.


========================================================================== Story Source: Materials provided by U.S._Army_Research_Laboratory. Note: Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2020/06/200618124758.htm

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