final presentation patrick melton daniel escobar 4/26/11
TRANSCRIPT
Device for Collecting Stress Images of Subtalar Joint
Final Presentation
Patrick MeltonDaniel Escobar
4/26/11
Hindfoot Anatomy
PurposeCreate a device that will apply stress to the subtalar joint for the best possible radiographic images to allow for accurate measurements and determine the stability of the joint.
Cobey View
Reilingh, M., Beimers, L., Tuijthof, G., Stufkens, S., Maas, M., & van Dijk, C. (2010). Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view. Skeletal Radiology, 39(11), 1103-1108.
Long Axial Alignment View
Reilingh, M., Beimers, L., Tuijthof, G., Stufkens, S., Maas, M., & van Dijk, C. (2010). Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view. Skeletal Radiology, 39(11), 1103-1108.
Semester Recap•Research Phase•Literature Review•Similar devices•EndNote
•Design Phase•Modeling/Drawings•Size Calculations
•Analysis Phase•Finite Element Analysis•Optimization
Completed Tasks
Final Design 30 degree plate
inclination with additional forefoot plate that rotates 15 degrees.
Sliding heelcup plate for various foot sizes.
Allows for footstraps to be placed in multiple areas.
Final Design
Utilizes two bolts that act as columns to angulate the foot for optimal positioning of the subtalar joint.
Dimensions - Bolts
Ø 1.125” UNF – 12 Hex Head bolt
15°
Ø 0.5” UNF – 20 Hex Head bolt
Dimensions - Hinges
Shoulder screw - Ø ½”,3/8”–16 thread with matching nut.
Shoulder screw – Ø ¼”#10–24 thread with matching nut.
Hinge: Ø 1.0” OuterØ 0.5” Inner
Hinge: Ø 0.5” OuterØ 0.25” Inner
Finite Element Analysis – Foot Plate
Max Displacement: .0618 in.
Finite Element Analysis – Foot Plate
Max Stress: 2550 psi Safety Factor: 3.92
Finite Element Analysis – Base Plate
Max Displacement: .0362 in.
Finite Element Analysis – Base Plate
Max Stress: 1180 psi
Safety Factor: n = 8.47
Finite Element Analysis – Forefoot Plate
Max Displacement: .0273 in.
Finite Element Analysis – Forefoot Plate
Max Stress: 8970 psi
Safety Factor: n = 1.12
Materials SelectionMost of the device will be
made from a radiolucent plastic called Delrin, manufactured by DuPont.Tensile strength – 400 ksiYield Strength – 10 ksiDensity – 1.42 g/cm3
Footstraps made from Nylon
Foam padding (Lux-R-Foam) on sliding plate, forefoot plate, and in heelcup.
CostMaterials Dimensions Cost
Delrin Sheets (4) 12" x 24" x 1" $159 ea.
Delrin Rods 1 ¼" D $7.50/ft.
½" D $1.56/ft.*
¼" D $0.52/ft.**
Lux-R Foam Padding 82" x 36" x ¼" $5.99
Velcro Straps (4) 1" W x 8" L $3.47/ft.
Total Material Cost $675
Shipping $50
Labor Hourly Rate Total Labor
Design $30 60 hrs
Machinist $25 16 hrs
Total Labor Cost $2200
Grand Total $2925
Questions?