Damien Wo (JH304), Fan Kaiqi (JH402), Pua Ek Hoe (JH302)
Title of the Project:Deployment of CubeSat Solar Panel Using
Shape-Memory Polymer
By:Damien Wo (JH304), Fan Kaiqi (JH402), Pua Ek Hoe (JH302)
National Junior College
Mr William Phua
Nanyang Technological University
Deployment of CubeSat Solar Panel Using Shape-Memory
PolymerDamien Wo (JH304), Fan Kaiqi (JH402), Pua Ek Hoe (JH302)
Abstract The recent discovery of the concept of 4D printing allows
for printed objects to self-assemble into 3D structures. This can
be done so right off the 3D printer using Shape-Memory Polymers
(SMP) which are able to temporarily alter its shape under heat
stimulus, exhibiting its shape-memory effect. With this useful
technology, we can replace the traditional CubeSat solar panel
deployment by printing parts which are able to self-assemble into
another different shape under the stimulus of radiation from the
Sun, thereby aiding in the deployment of solar panels.
Background and Purpose of Research Area The basic cube satellite
(CubeSat) is a type of research spacecraft called nanosatellites
with a volume of exactly one litre. Due to its low-cost, short
development time and the ease of deployment, the CubeSat has become
increasingly popular to launch satellites built using off the shelf
electronics. It has been used extensively on space research,
geographical information gathering, and communication applications.
According to research and the National Aeronautics and Space
Administration (NASA), there has been numerous launches of CubeSat
over the past 10 years, and many of them were successfully deployed
[1,2]. Since CubeSats have been conceived, traditional CubeSat
solar panel deployment have relied on simple aluminium or stainless
steel torsion springs to deploy the solar panel array once in
orbit. In transit into orbit, the solar panels are pressed against
the side of the CubeSat with the torsion springs compressed. When
in orbit, a nichrome wire with high resistance is heated up using
on board batteries, allowing for a thermal knife to cut through the
nichrome wire. When the wire is cut, elastic potential energy
stored in the torsion springs during transit is released, allowing
the solar one array to achieve a deployed state. However, based on
research, the traditional usage of torsion springs may not always
guarantee a successful launch of the satellite. For example, spring
drives must use a minimum torque ratio of four [3]. If the torque
ratio is incorrect, the satellite would be unable to reach its
deployed state, therefore resulting in deployment failure. The
primary goal of this project is to utilise shape-memory polymers
(SMP) together with 3D printing to deploy the solar panel array,
replacing the traditional method of deployment mentioned above. 3D
printing can be made used of in many different ways, and there are
various applications for such technologies, including architecture,
aerospace, dental and medical industries. Based on research, there
have been successful launches of satellite with 3D printed parts
[5]. However, the addition of another dimension is something that
has just been recently discovered. 4D printing allows materials to
self-assemble into 3D structures. This concept was initially
proposed by a faculty member of Massachusetts Institute of
Technology, Skylar Tibbits [6]. 4D printing includes an added
capability of embedded transformation from one shape to another,
directly off the 3D printer. This can be easily done by utilising
SMP. (b)(a)
SMP are polymeric smart materials which can exhibit a radical
change from a rigid polymer to a very elastic state, then to a
rigid state again. It can be deformed to other shapes upon a
stimulus, without degradation of the material. SMP exhibiting a
shape-memory effect have both a visible, current (temporary) form
and a stored (permanent) form. They hold the major advantage of
high elastic deformation, straining up to 200% and even more for
most types of polymers. [4] Additionally, SMPs are also easy to
actuate, such as by heating using either the sun radiation or
electric heating. Through heating, deformation and then cooling, a
part made of SMP can easily have its shape altered temporarily,
exhibiting its shape-memory effect (Figure 1). This is otherwise
known as the thermally-induced shape-memory effect (SME), which is
the capability of a material to change its shape in a predefined
way in response to heat [10]. This shape change is the
entropy-driven recovery of a mechanical deformation, which can be
obtained via an exertion of external stress, then fixed temporarily
by physical crosslinks [10], thereby allowing for an SMP structure
to remain in its temporary form. However, SMP are stable only at a
certain temperature range. In this case, a glass transition
temperature (Tg) has to be reached before the material can become
relatively soft, allowing for free deformation and random twisting
via rotations about backbone bonds of the polymer while maintain a
maximum entropy and a minimal amount of internal energy while
deformation occurs [4]. Figure 1: Picture of SMP materials in its
original shape (a) and deformed shapes(b).
Thus, we can apply this concept to CubeSat solar panel
deployment by printing SMP structures which are able to
self-assemble into another different shape under the stimulus,
which in our case will be radiation from the Sun, in order to aid
in the transformation from a stored state to a deployed state in
space. This not only eliminates the need for highly complex
deployment mechanisms, but also deployment-control system and
massive launch canisters [9]. Research Method and Materials We used
SketchUp software to make and design our SMP structures which were
to be printed, as shown in Figure 2. The type of SMP we are using
for our project is the single-component SMP which uses Fullcure720
as its single-component material. It is a type of semi-translucent
photopolymer for standard plastics simulation. It combines high
dimensional stability with surface smoothness, and also allows for
easier control of the transformation temperatures. There is a wide
range of applications, including visualization of liquid flow;
colour dying; medical applications; artistic and exhibition
modelling.
(i) (ii)Figure 2: Template of designed SMP structure in (i) side
view and (ii) top view
For our structures to be printed, Polyjet 350, a 3D printer was
used (Figure 3). Dimensions of the printed structures were 30mm by
40mm by 1mm. It took 20 minutes for 3 of the similar structures
(Figure 2) to be printed by the 3D printer which must be heated up
to 70C before printing can commence. The printer makes use of the
selected SMP (Fullcure 720) material to print out the designed
structures. To test out our structures, we first heated a beaker of
water to 60C using a heating plate. A thermometer was used to
measure the temperature of water. Once the temperature of water is
at 60C, we immersed our structure into the beaker of water. The
thermometer was used to ensure that the temperature of water
remains constant at 60C throughout this process. Due to its size
and weight, the structure may float on the surface of the water.
Thus 2 glass rods were used to hold the structure down and ensure
that it was fully immersed into the water throughout this process.
The printed structure was allowed to be immersed in water for 6
minutes before it was carefully taken out with a pair of tweezers
and then placed on a smooth, flat surface. Deformation was made by
using a pair of tweezers. The structure was pressed together in the
horizontal direction until it collapses together (Figure). After
cooling down for a minute, the structure will remain in its
deformed state. This represents the state of the SMP structure
before deployment occurs in space. Solar panels, as represented by
thin shaded plastic sheets (Figure) will be folded as shown in
Figure. Figure 3: Picture of Polyjet 350 3D printer used
Results and Discussions
Conclusion
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