UTRGV
/ COLLEGE
OF ENGINEERING AND COMPUTER SCIENCE / MECHANICAL
ENGINEERING DEPARTMENT
TEAM
4: Furtherance of a prosthetic fin to improve range of motion of injured sea turtles.
|
SDI Students (L-R) |
·
Oleg Riabov ·
Charlize Samperio ·
Uxia Pereira Alonso · Alejandro Galvan |
|
Faculty Advisor(s) |
· Mr. Marcos Villarreal · Dr. Javier Ortega |
|
Course Instructors |
· Dr. Noe Vargas Hernandez · Mr. Gregory Potter |
WHAT
IS THE PROBLEM WE ARE TRYING TO SOLVE?
WHY
IS THIS PROBLEM IMPORTANT?
LEARN
MORE ABOUT OUR DESIGN PROCESS
Welcome!
We are team #4 “Engineers United”, Oleg, Charlize, Uxia, and Alejandro worked
on this project during the Spring and Fall of 2023. Our project is titled Furtherance
of a prosthetic fin to improve range of motion of injured sea turtles. The
problem we tackled was that Allison, a 17-year-old Atlantic green sea turtle,
lost 3 of her fins due to a predator attack. We work to recover her life once
again by designing a prosthetic device that will allow her to swim freely
without requiring any further assistance from the Sea Turtle Inc staff, encountering
discomfort, and imbalance. We hope that you enjoy this project as much as we did.
Click on the Welcome Video below!
Watch the Welcome Video!
The
problem we identified is that it is common that many sea turtles tend to lose
fins frequently due to predator (shark) attacks or getting tangled with
nets. The rates of these unfortunate
circumstances may not decrease anytime soon due to sharks being the largest
predator of the sea turtle. The previous team’s prosthetic granted Allison the
ability to move upwards and downwards, but it is also important for Allison to
move in a rotational motion, which mimics her normal range of motion when she
had all four fins. Allison’s harness is solid and is attached to her shell, but
it will need to be flexible to prevent any compression to her organs. Making a
prosthetic fin adjustable to Allisons shell is important for several reasons as
she will be able to swim comfortably, safe, and efficiently. It will also help
to ensure that the prosthetic continues to fit well throughout the Allison’s
life and provide the best possible outcome for well-being and survival for her
and any other sea turtles encountering similar issues.
Many
sea turtles have lost fins due to human activities such as fishing gear
entanglement, boat strikes, plastic pollution and because of this, prosthetic
fins were developed. A sea turtle prosthetic fin is a device that is designed
to help a turtle swim more efficiently if it has lost its fin due to injury or
other reasons. This type of prosthetic is usually made of a lightweight
material such as plastic or silicone and is attached to the turtle’s body using
straps or other secure methods. The design of the prosthetic fin can vary, but
it is typically shaped like a normal fin to help the turtle swim more
efficiently. In some cases, a turtle prosthetic fin may be used as a temporary
solution while the turtle is healing, while in other cases it may be a permanent
solution to help the turtle adapt to its injury and continue to swim normally.
Sharks and sea turtles are both aquatic
animals, and they both have adaptations that allow them to swim efficiently
through the water. However, the way that they swim is quite different, but in
our case, we are using the shark fin to help Allison swim straight and have the
ability to reach the surface without any assistance. Sharks are known for their
powerful and efficient swimming style, which is characterized by their
undulating, S-shaped movement. This movement is generated by the lateral
undulation of their bodies, which generates a rolling wave of movement that
propels the shark forward. The shark's fins also play a role in its swimming
style, as they help to stabilize and steer the animal as it moves through the
water.
Sea turtles, on the other hand, swim using a
different technique known as flipper propulsion. In this type of swimming, the
turtle's flippers provide the primary source of propulsion, while the body
remains relatively still. The turtle's flippers work by generating lift and
drag, which move the animal forward through the water. Unlike sharks, sea
turtles do not undulate their bodies to swim.
Overall, having all four fins is important for
sea turtles because it allows them to swim efficiently and effectively. Sea
turtles rely on their flippers to navigate the ocean, find food, avoid
predators, and migrate long distances. Each flipper plays a crucial role in
helping the turtle swim and maneuver in the water. A sea turtle prosthetic fin
can help improve the quality of life for a turtle that has lost its fin and
ensure that it can continue to swim and live a healthy life.
Our
main motivation to work on this project is that injured sea turtles such as
Allison get specialized help at rehabilitation and care facilities such as Sea
Turtle Inc, but they often have problems with their fins that can only be
helped with innovative engineering solutions. Anything dealing with sea turtles
is highly regulated and must be carefully done to ensure safety of the animal. With
support from our stakeholders, we design and build a working prototype for
Allison the sea turtle.
“We propose the design of a prosthetic fin
that is highly adjustable, lightweight, and easy to use. The design will
incorporate a slim harness with an adjustable mechanism to attach it and will
provide good balance for the sea turtle Allison.”
After
understanding the problem in depth, we explored various potential solutions and
selected the best concept. We will have a lightweight and slim harness composed
of 3D-printed and possible metal alloy materials with a ratcheting adjustment
and attachment system as well as a stabilizing fin for complete balance and
maneuverability. Here is an early rendition of our design:
Once we defined a clear solution idea
(i.e. concept), we applied our engineering knowledge to transform it into a
real product. These were some of the important design challenges and how we
approached each one of them:
1. The fin had to have high mobility, low fluid
resistance, and high maneuverability:
Some fin designs we envisioned were a
turtle-like fin, a dolphin-like fin, and a shark-like fin. Here is an example
with a shark fin:
2. The attachment and adjustment had to be low
cost, high durability, and good accessibility:
For attachment and adjustment
mechanisms, we studied usings hooks, pegs, magnets, spin buckles, ratcheting,
and elastic to satisfy our design parameters. Here is an example with a spin
buckle:
3. The harness had to have high stability, high
flexibility, and be lightweight:
In regard to the harness, we needed to
attach the prosthetic to Allison in very specific points on her shell so as not
to hurt her. We proposed having two, three, and four attachment points that
would check all the boxes. Here is an example with four harnessing points:
4. The propulsion method had to be low cost, high
power, and lightweight:
In terms of propulsion through the
water, the most effective solution was just to use Allison, however, we also
considered using a motor with a propellor and using a centrifugal water pump.
5. Allison’s balance had to be improved from last
year’s design:
Some ways we thought of to improve
balance was by differing the number of fins. We thought that one, two, and
three fins would be a good starting point. Here is an example of a three-fin
design:
We found that physical prototyping was
very helpful to increase our understanding of the problem and the feasibility
of our solutions. Our first prototypes were simple but useful and we continued
evolving into more complex ones.
This was our first prototype, it may
be simple, but it helped us understand that attachment points, fin design, and
adjustment mechanisms were going to be incredibly important to the success of
our project.
First prototype Prototype
of concept variant 8
At a point during the summer, the sea
turtle Allison sadly passed away. The team and our clients and teaching crew
thought best to turn our focus onto building a universal harness system that
could work for any size of turtle.
During the summer and the first part
of the second semester, the team worked on making large improvements to the
prototype. Some of the improvements the team made include a Velcro adjustment
system, aluminum frame, and 3D printed components that can be remade quickly
and inexpensively.
Below is the prototype the team made
at the midterm of the semester. This prototype looks very similar to the final
product, however there are some obvious differences.
Midterm prototype
We chose to keep concept variant 8 to
be our final design of the prosthetic. Here is the sketch and the CAD of that
concept variant.
After doing tensile testing on two 3D
printed materials, we decided to use PETG and TPU for our project. After making
design improvements and alterations, such as changing the spin buckle in
Concept Variant 8 to a ratcheting system, we made an updated CAD model of our
design.
The
team also made 3D printed prototypes of the project and we want to assemble a
complete prototype by the summer.
During
the second semester of senior design, our team had the idea to introduce links to
further improve the range of the prosthetic arms of the prototype. Below is a
sketch of how the links were proposed to work:
After
assembling our midterm prototype, the team moved on to testing.
We
first ran finite element analysis on the entire structure as well as on the fin
assembly itself.
Displacement of the structure as viewed from
the front
Von Mises stress concentrations of the
structure
The
team turned to doing impact testing on the materials we wanted to use,
primarily PETG and TPU.
We
ran IZOD impact testing on samples of the materials we used for the harness.
The two 3D printed materials we used are polyethylene terephthalate glycol (PETG)
and thermoplastic polyurethane (TPU). We found that these two materials were
the best of the possible materials that we could have used based on what we had
available.
The
team also ran tensile testing on the materials. This testing helped us prove
that using TPU for the fin and PETG for the rest of the parts of the harness
was the best combination. TPU is flexible and can handle repeated loads so it
will not break even if it is bent back and forth numerous
times like we observed Allison was doing. PETG for the rest of the parts was
used because the material did not break down in a water environment and handled
stress better than PLA.
Unfortunately,
the team was unable to test the harness in a real-life environment, such as
with a real sea turtle. The team made a mockup of how the harness should have
been attached to a sea turtle.
Our project is a proof of concept that
requires further development, these are some of the pending items:
· Improvements to the adjustment of the harness
· Optimization of the design to save material
and weight
· Fin design to best suit the application of the
harness
IN CONCLUSION
This project has been a pleasure to
work on for the team. We picked up this project from the previous year and we finished
it by making the necessary improvements to the design so that it may be someday
beneficial to any sea turtles with ailments, regardless of size. The team
believes that there can be future work that could be done to fit this harness
to the need of any staff working with sea turtles, but we think that the
current version is the best version that has come of this project.
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We
went through a meticulous design process to arrive to the final solution. The
information on this page is a summary intended for the public. To learn about
the project details, contact Dr. Noe Vargas Hernandez at noe.vargas@utrgv.edu
The team received help from various
persons, their help was critical to our success, we would like to acknowledge:
· Our course instructors Dr. Vargas and Mr.
Potter for helping guide us through our project.
· Our faculty advisors Mr. Villarreal and Dr.
Ortega for helping answer our questions about engineering and design.
· Our client Sea Turtle Inc for valuable
information that helped us design and improve solutions to their problem.
· Other UTRGV faculty including
Dr. Jones and Mr. Cano.