P14042: Una -Crutch

1. P14042: Una-Crutch Right Move, Right Place, Right Time Subsystems Design Review Ana Allen Joanna Dzionara-Norsen Beverly Liriano Dan Sawicki

2. Agenda

3. Review (weeks 1-6)

4. Current Product

5. P14042 Problem Statement

6. Additional Project Deliverables

7. Prototypes Introduced Week 6 C B A E D F

8. Identifying Critical Subsystems

9. Risk Assessment

10. Identifying Critical Sub Systems

11. Functional Decomposition

12. Identifying Critical Sub Systems

13. Engineering Requirements

14. Identifying Critical Sub Systems

15. System Architecture

16. Identifying Critical Sub Systems

17. Identifying Critical Sub Systems Connective Mechanism

18. Identifying Critical Sub Systems Connective Mechanism Axilla Pad/ Handles

19. Identifying Critical Sub Systems Connective Mechanism Axilla Pad/ Handles Frame

20. Critical Subsystems Defined

21. Proof-of-Concept

22. Prototypes Introduced Week 6 C B A E D F

23. Prototypes Introduced Week 6 C B A E D F REVISED

24. Pros: • Compact Design • Usable for all ages • Stable • Cons: • Not necessarily aesthetically pleasing • Two separate bases • Pad is in contact with the ground Prototype G Male/female mold Pin

25. Pros: • Lightweight • Easy to manufacture • Sliding button connective mechanism • Cons: • Design resembles standard axilla crutch Prototype H Sliding button

26. Prototypes to Create 1. Axilla Pads and Handles 2. Frames and Connective Mechanisms C B G H

27. Axilla Pads and HandlesPrototypes Created

28. Frames and Connective MechanismsPrototype B and C C B

29. Frames and Connective MechanismsPrototype G G

30. Frames and Connective MechanismsPrototype H H

31. Prototype Test Plan

32. User Feedback Axilla Pads and Handles

33. User Feedback Axilla Pads and Handles

34. User Feedback Frames and Connective Mechanisms

35. Second-Order Analysis

36. Magnetic Analysis

37. Magnetic AnalysisMagnetism Physics on a Crutch • Pull Force: quantity required to separate two attracting magnets. • Pull Force Equations: The Lorentz Equations • Pull Force Increases as Area Increases. • Pull Force Decreases as Distance Increases.

38. Magnetic AnalysisConfigurations Analyzed

39. Magnet Overview Prototype Design Tested Note: If used in final design, magnets will have a small distance separating them.

40. Bike Clamp Analysis • Split-Ring Clamp Type Shaft Collar • Analysis: • Torque necessary to achieve pre-load • Axial holding force of seat post collar • Hoop Tension in collar

41. Bike Clamp AnalysisTorque in Cap Screw • Assume: • Cap screw is coarse pitch • Low or medium carbon • Non-permanent connection • Screw diameter = 6 mm • Torque = 6.11 Nm

42. Bike Clamp AnalysisAxial Holding Force • Assume: • Coefficient of friction = 0.61 • Fx = 13,000 N

43. Bike Clamp AnalysisHoop Tension • Assume: • Collar width = 12 mm • Internal radius 6.35 mm • Internal pressure = 7.08 MPa • Fh = 540 Pa

44. CAD Model: B/C Prototype Cheetah Leg Connection Mechanism Grip Connection Mechanism

45. Spring Analysis • Analyzing Spring at Base of Crutch. • Normal Force = Spring Force • N = user load • Two Stresses on Spring: • Torsion Shear Stress • Direct Shear Stress N

46. Spring Analysis Results • Stress absorbed by the springs results in a large stress. • May give user more endurance to use crutches longer.

47. Deflection of Cheetah Leg Base • Assume: • Carbon fiber material • Circular cross-section • r = 0.75in = 1.91x10-2m • R2 = 0.3 m • Deflection = 0.08in = 0.002m P M P R2 D P

48. Feasibility

49. Manufacturing Processes

50. Brinkman Lab Resources