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Client:David Beebe, Ph. DBiomedical EngineeringAdvisor:Naomi Chesler, Ph. DBiomedical Engineering. Abstract. Many running injuries are caused by continued use of improper or worn running shoes. The increase in incidence of injury can be directly correlated to the degradation of the materials used in shoe sole construction. The degree to which a shoe sole degrades is directly related to the changing elasticity of the material. Two different methods are proposed to measure elasticity in a s1144
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1. Team Members:
Brant Kochsiek BSAC
Steve Pauls Team Leader
Tim Rand Communicator
Brian Schwartz BWIG
2. Client:
David Beebe, Ph. D
Biomedical Engineering
Advisor:
Naomi Chesler, Ph. D
Biomedical Engineering
3. Abstract Many running injuries are caused by continued use of improper or worn running shoes. The increase in incidence of injury can be directly correlated to the degradation of the materials used in shoe sole construction. The degree to which a shoe sole degrades is directly related to the changing elasticity of the material. Two different methods are proposed to measure elasticity in a shoe sole. Strain gauges and Flexi-Force piezoelectric force sensor devices have been added to an integrated circuit that will indirectly measure shoe sole elasticity. Once calibrated, each circuit will have a diode that lights when a shoe sole is worn past its useful life.
4. Problem Motivation Running shoes last 300-500 miles
Worn shoes do not always appear worn
Incidence of injury increases with worn shoes
5. Client Requirements Design a device that:
Measures shoe sole elasticity
Fits ergonomically into the shoe sole
Is lightweight and small so as to not hinder performance
Operable for the life of a running shoe (300-500 miles)
Has a clear indicator so the runner will know when the shoe is sufficiently worn
6. Shoe Materials Ethylene Vinyl Acetate (EVA)
Polyurethane (PU)
7. Nominal Running Style
8. Pressure Distribution while Running
9. Comparator/LED
Differential Amplifier
Drive Circuit
Voltage regulator
Force Sensor Circuit
10. FlexiForceŽ Sensors Comparison of forces from top to bottom
11. Strain Gauge Circuit Comparator/LED
Differential Amplifier
Strain Gauge
12. Strain Gauge Constant Poissons Ratio (v),
Stress-Strain (d-e) for Elasticity (E)
15. Preliminary Testing
16. Current Standing Preliminary tests showed flaws in our circuit and sensor set up
Circuit is being reworked and future testing will soon follow
Research into exact placement of sensors in shoe sole is ongoing
17. Testing Procedure Apply static loads to sensors imbedded in silicone polymer
Loads applied in sets of 4000 which correlates to about a 6 mile run
Following each set:
Elasticity of material will be measured
Output of circuit will be read from multimeter
Output vs. elasticity will be plotted
18. MTS Servohydraulic Machine We plan to use an older version of this machine found in the Materials Testing Lab in Engineering Hall
19. Future Work Mold strain gauge into silicon mold
Test both prototypes to simulate 500 miles of running wear
Determine the correlation between the output of each device and elasticity
Determine shoe sole wear threshold value
Integrate chosen device and corresponding circuit into a shoe sole for testing
Research and go through necessary human subject testing procedures
Undergo human testing of the prototype shoe
Possible patent application
20. References 1000 Hz High-Cycle Fatigue Testing Systems. MTS Inc. Accessed 4/28/04 URL: http://www.mts.com/menusystem.asp?DataSource=0&NodeID=1483
Anatomy of a Running Shoe. American Running Association.
Accessed: 04/26/04 URL:
http://www.americanrunning.org/displayindustryarticle.com.
Biomechanics Laboratory. Accessed: 04/24/04 URL: http://www.uni-essen.de/~qpd800/index.html.
BTopenworld. Accessed: 04/24/04 URL:
http://www.btinternet.com/~bury_rd/cheatah.jpg.
FlexiForce Force Sensors. Tekscan. Accessed: 04/25/04 URL:
http://www.tekscan.com/flexiforce/flexiforce.html.
Forrest Gump Pictures. Cox Members High Speed Internet. Accessed 02/26/04 URL: http://members.cox.net/gumpisms/hanks1.jpg
Hennig, E. M., & Milani, T. L. 1995. In-shoe Pressure Distribution for
Running in Various Types of Footwear. Human Kinetics Publishers
Inc., New York.
Mills, N., & Verdejo, R. 2002. Performance of EVA Foam in Running
Shoes. Blackwell Inc., UK, Birmingham.
Runners World. Runners World. Accessed:04/27/04 URL: http://www.runnersworld.com/.
Running Shoes. ePodiatry. Accessed: 04/26/04 URL:
http://www.epodiatry.com/running-shoes.htm,
21. Special Thanks Professor David Beebe
Professor Naomi Chesler
Amelia Cosgrove
John W. Dreger
Ivar Meyvantsson
Professor Tim Osswald
Professor Mitch Tyler
Paul Victorey
Professor John Webster