1. Feet for All
Quarterly
Report
Kevin Fontenot, Hayden Slack, Charles
Sprague, Vladislav Voziyanov
2/26/2013

2. Specific Aims
• 1) Confirm the selected materials are suitable for
use in low-income countries.
• 2) Design an ankle that functions multi-axially when
combined with the foot.
• 3) Develop a procedure that optimizes
manufacturing time.
• 4) Select a foot that optimizes the function of the
multi-axis ankle and foot system.

3. Maker Bot
• Used to create first
looks-like model
• Scaled
• Allowed for us to see
how:
o Ankle components fit together
o How it will move

4. Range of Motion Device
• White board
• Protractor
• Line drawn for front of
leg and top of foot for:
o Regular stance
o Toe off
o Heel strike
• Angle between the
two was measured

5. Construction
• Drill Press
• ¼ “ and ¾ “ routing bits
• Water jet
• Polyurethane Bushing
• 12”x12”x3”
polyethylene sheet
o Top Ankle Plate
o Bottom Ankle Plate
o Foot

6. Top & Bottom Plates
• Started out as 3” cube
• Milled down to the
appropriate size
• Shaped according to
the model

7. Foot
• Cut from polyethylene
sheet using a water jet
• Model drawn in
SolidWorks
• Based off the Niagara
foot
• 10”x3” so that it can fit
in a shoe

8. Cost
• 12”x12”x3”- • $108.94
Polyethylene sheet $ 10.24
• 1-SS Hex Bolt 7/16” • $2.45
• 2-SS Washers 7/16” • $1.02
• 1-SS Nut 7/16” • $0.53
• 1-PUR Bushing • $4.00
• Total • $18.24

9. Testing
• Tinius Olsen
• Slowly increased the
load
• Compressive testing
• Observed Force and
vertical displacement

10. Testing

11. Data

12. Results

13. Finite Element Analysis
• SolidWorks Simulation
Package
• Static Study
• Nonlinear Study

19. Specifications
Product Specifications Design Specifications
1. Multi-Axis 1.1 Inversion and eversion plane of motion
2. Weight 2.1 Device weighs less than 2 lbs
3. Length 3.1 Device is small enough to fit onto most
feet
4. Manufacturing Time 4.1 Part fabrication is less than 5 hours
4.2 Device assembly is less than 30 minutes
5. Supports User 5.1 Device supports users 50 – 200 lbs
6. Bolts, Washers, and Nuts 6.1 Aluminum 2024-T3
6.2 Stainless Steel 17-4, 303, 316, 440, 445
7. Ankle Body 7.1 Plastic (High Density Polyethylene,
Polyurethane)
8. Foot 8.1 SACH Foot
9. Cost of Prototype 9.1 $85 ± $15
10. Reliability 10.1 Device exceeds 3,000,000 cycles
11. Aesthetics 11.1 Resembles a physiological foot
12. Repair 12.1 Repaired on site
13. Operating Environment 13.1 Indoors, outdoors, moist, muddy, water,
rocks, and trees
14. Operating Temperature 14.1 -50 – 124 degrees Fahrenheit
15. Ankle Adaptability 15.1 Ankle attached to current foot solutions
16. Rubber Bushing 16.1 Made from polyurethane

20. 2 nd Iterative Design
• Rounded the ankle
• Added a second bushing
• Added a “locking” mechanism on the Bottom Ankle
Plate
• Material choice for the bushing

21. Iterative Design Process
Weight Polyurethane Rubber Spring
Availability 0.35 6 2.1 8 2.8 5 1.75
Varying Stiffness 0.05 10 0.5 5 0.25 9 0.45
Maintenance 0.05 9 0.45 7 0.35 6 0.3
Corrosion Resistant 0.20 9 1.8 5 1 4 .8
Low Cost 0.10 6 0.6 9 0.9 5 0.5
Durability 0.25 8 2 6 1.5 7 1.75
Totals 1 7.45 6.8 5.55

22. Modeling
• SolidWorks
• Redesign
o Top Plate
o Bottom Plate
• Components
o Top Plate
o Bottom Plate
o 2xBushings
• Assembly

26. Questions