Tech Briefs Magazine - November 2023 - 30

Manufacturing
& Materials
Finalist
TenseFlatables: 3D-Printed
Tensegrity-Assisted
Inflatable Structures
William Johnston, Dr. Bhisham Sharma
Michigan Tech University
Houghton, MI
K
eeping structures lightweight without adversely affecting their
functionality is a major engineering challenge. Inflatables -
structures that gain their load-carrying capabilities from pressurized
air within a tensioned hyperelastic skin - offer a unique solution
to this problem. Although lightweight, inflatables are rarely
used for engineering applications because of their inability to meet
tight dimensional tolerances or sharp-edged design features.
Current fabrication methods limit inflatable designs to simple,
rounded geometries and do not allow the creation of inflatables
with complex topological features. The current fabrication method
of fusing 2D patterns to achieve 3D post-inflation shapes precludes
the fabrication of inflatables with complex post-inflation shapes.
Additionally, current inflatables lack the mechanical stiffness requisite
for engineering applications.
TenseFlatables solve both these issues while simultaneously
simplifying the overall design and fabrication process. Each
TenseFlatable has two important components: an external geometry
that can be customized by the user and an internal
tensegrity architecture that allows the TenseFlatable to achieve
high dimensional tolerances while improving its overall
load-bearing capabilities. As with traditional inflatables, TenseFlatables
can be easily deflated and stowed.
" As aerospace engineers, we are continually seeking ways to
decrease structural weight without sacrificing strength, " said
Student Team Lead William Johnston. " The idea of TenseFlatables
stemmed from our earlier efforts to devise methods for
printing thin fibers and impervious hyperelastic membranes for
acoustic applications. From this, it was a natural progression for
us to use these methods to print lightweight inflatables for structural
applications. The idea for an internal tensegrity mesh came
as we tried to find ways to make inflatables dimensionally precise
and stiff enough for load-bearing applications. Throughout,
we focused on using 3D printing because it allows us to consolidate
these features into a singular, scalable workflow, " he added.
TenseFlatables are manufactured using a patent-pending method,
which uses an extrusion-based additive manufacturing technique
to fabricate the flexible, airtight hyperelastic skin and the internal
tensegrity mesh within a single workflow. The additive
approach is significantly more efficient than the current methods
30
that rely on form-finding complex 2D patterns before fusing them
together to achieve 3D post-inflation shapes.
Reliance on an additive technique allows to customize the external
shapes as well as the internal tensegrity mesh and achieve application-specific
design and performance. The simplification of
the design and manufacturing process makes it significantly cost
and time efficient, while allowing at-scale and at-rate manufacturing
of TenseFlatables via automation.
A major challenge the team faced in design and development
was to identify the correct process parameters to reliably print
thin skins that remain hyperelastic as well as airtight. " The layer-by-layer
technique of the fused filament fabrication process
typically results in inter- as well as intra-layer air gaps or porosities.
Avoiding these porosities while retaining stretchability is
crucial to the fabrication of robust inflatables, " said Johnston.
" Another significant challenge was to ensure repeatable fabrication
of cylindrical fibers that constitute the internal tensegrity
mesh and to achieve a strong fiber-skin interface connection.
Eventually, we were able to overcome these challenges, and we
can now print complex inflatables that can be optimized to
achieve desired mechanical performance, " he added.
TenseFlatables have the potential to significantly outperform
conventional inflatables in their form and functionality. The
ability to create lightweight structures reliant on pressurized air
can enable the design of novel multifunctional technologies for
use as automotive, aircraft, and spacecraft components that
help reduce fuel consumption. Their deploy-and-stow ability
makes them ideal for aerospace and hypersonic deployable
supports and decelerators.
According to Johnston, TenseFlatables can revolutionize fields
ranging from aerospace to medicine. " Their lightweight, deployable
nature is ideal for aerospace components, reducing fuel consumption.
Medically, they can enhance procedures like Balloon
Kyphoplasty and rotator cuff surgeries. Additionally, when filled
with reactive hydrogel, they're suitable as diagnostic pills for illnesses
like cancer. We are also exploring potential naval, architectural
uses, and alternatives to air-based systems, " he said.
For more information, visit https://contest.techbriefs.
com/2023/entries/12412.
www.techbriefs.com
Tech Briefs, November 2023
http://www.createthefuturecontest.com https://contest.techbriefs.com/2023/entries/12412 http://www.techbriefs.com
Tech Briefs Magazine - November 2023

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