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Winter Sports Wrist Brace

Winter Sports Wrist Brace. Design, Manufacture, and Test Matt Anderson Summer ‘06. Introduction. Scaphoid fracture most common snowboarding wrist injury Beyond 60 degrees rearward rotation fractures occur. Objectives. Design a brace to prevent wrist from rotating beyond 60 degrees

georgia-kemp
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Winter Sports Wrist Brace

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  1. Winter Sports Wrist Brace Design, Manufacture, and Test Matt Anderson Summer ‘06

  2. Introduction Scaphoid fracture most common snowboarding wrist injury Beyond 60 degrees rearward rotation fractures occur

  3. Objectives Design a brace to prevent wrist from rotating beyond 60 degrees Provide limited wrist movement to increase user compliance

  4. Concepts Leaf spring Hydraulic Damper Air Spring

  5. Concept Selection Leaf spring • Limits wrist movement forward and rearward • Reaction force dependent on deflection

  6. Concept Selection Hydraulic Damper • Limits wrist movement rearward only • Reaction force dependent on velocity of fall

  7. Concept Selection Air Spring • Limits wrist movement rearward only • Reaction force dependent on deflection

  8. Concept Selection Hydraulic damper adapts to user’s weight and travel velocity

  9. Damper Components Fluid Chamber O-Ring Grooves Accumulator Piston Piston

  10. Math Model 50 lb weight dropped from 26 in results in impact velocity of 11.81 ft/s Required damping coefficient determined for overdamped system Solution to an overdamped system:

  11. Math Model 0.75 in piston assumed Calculations to determine displacement for 60 degrees of rotation:

  12. Math Model Initial velocity used to graph response of system Max displacement less than allowable displacement of 0.562 in

  13. Math Model Required damping coefficient determined to be 300 lb*s/ft Equivalent damping coefficient for hydraulic damper required • Damping proportional to square of velocity

  14. Math Model Equivalent damping coefficient determined using: • Work performed by damper • Pressure drop across orifice • Force on piston • Work performed by viscous damper Damping coefficient used to determine required orifice diameter of 0.02 in

  15. Test Apparatus Designed to drop 50 lb from height of at least 26 in String potentiometer used to measure deflection Labview utilized to record deflection as function of time

  16. Test Apparatus

  17. Test Method Determine voltage output at contact position Raise falling weight and measure distance from bottom of weight to top of brace Start Labview program Release weight from starting height Convert output voltages to displacements

  18. Test Results First round of tests showed very little damping capability • Caused by air inside cylinder • Filled cylinder inside oil bath to alleviate problem

  19. Test Results Theoretical Second round of tests showed very promising results Max displacement matched math model Experimental

  20. Test Results Tests prove that brace is capable of preventing rotation beyond 60 degrees

  21. Future Recommendations Conical compression spring to limit space Accumulator spring DFA/DFM Plastic injection molded components Integrate brace into winter glove

  22. Conclusion Scaphoid fractures can be prevented by limiting rotation to 60 degrees or less Maximum displacement test results matched math model Hydraulic damper capable of preventing over-extension of wrist Hydraulic damper adapts to user weight and travel velocity Brace should be integrated into a winter glove using injection molded plastic components

  23. The End Special thanks to Dr. Farris and Dr. Blekhman Questions?

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