Figure 1 Schematic of prosthetic pylon design [4]

Figure 2 Most common commercial prosthetic pylon design. Courtesy of Excell Orthotics and Prosthetics in Denton Texas.

Figure 3 Schematic of Friction Stir Process [7]

Figure 4 Image showing the proposed pylon design b) CAD model showing proposed pylon design fully integrated into the prosthesis system

Figure 5 Trial FSP of Ti 6246 plate in order to determine optimal processing parameters

Figure 6CAD model showing the four plates for the proposed pylon design b) image showing four plates cut on the water-jet

Figure 7 Euler Column Buckling: End Conditions Constant Schematic [13]

Figure 8 Alternating stress vs. cycled data imported into ANSYS Workbench

Figure 9 a) ANSYS 3D model of the proposed pylon b) Meshed model in ANSYS c) Boundary conditions imposed on the pylon design for modeling analysis

Figure 10 Loading options under Fatigue tool in ANSYS Structural Modeler.

Figure 11 Stress distribution in proposed pylon model simulated in ANSYS

Figure 12 Factor of Safety distribution in the pylon model simulated in ANSYS at 550lbs load

Figure 13 Euler Buckling Analysis for each slender bar in the proposed pylon design

Material

Mass (g)

Yield Strength (MPa)

Ultimate Strength (MPa)

Al 1060

84.99

27.57

68.94

Al 6061

84.83

55.15

124.08

Al7075-O

88.29

95

220

Ti6Al-2Sn-4Zr-6Mo (0.75 mm Thickness)

46.27

1048

1185.9

Ti6Al-2Sn-4Zr-6Mo (with FSP-0.75 mm Thickness)

31.08

1738

2020

Table 1 Summary of properties of materials for pylon applications

Product

Material

Length
(mm)

Weight at 127mm (g)

 

Proposed Design

Titanium

127

0.057

 

A-500 XHD [10]

Carbon Fiber

304.8

 0.098 – 41.8% difference from prop. design

 

5209C [11]

Carbon

304.8

 0.112 – 49% difference from prop. design

Table 2 Summary of different pylon characteristics

Trial #

Spinning speed (rpm)

Travel speed (in/min)

Environment

5, 4 & 3

600

1

Air

1, 2

1000

1

Air

6

1000

1

Argon

Table 3 Summary of processing parameters for each trial in Figure 5

Load

Pressure

Euler Alternating Stresses

Safety Factor

Lbs

N

Pa

Psi

Min

Max

Min

600

2669

291,192

42.2

19.6

1.4 e8

1.96

550

2447

266,926

38.7

17.9

1.3 e8

2.14

500

2224

242,660

35.2

16.4

1.2 e8

2.35

450

2002

218,394

31.7

14.7

1.1 e8

2.61

400

1779

194,128

28.2

13.1

9.6 e7

2.94

350

1557

169,862

24.6

11.5

8.4 e7

3.36

300

1334

145,596

21.1

9.8

7.2 e7

3.92

250

1246

121,330

17.6

8.2

5.9 e7

4.71

Table 4 Summary of Fatigue Analysis