1. Engineering 309: Machine Design I Instructor: Dr. Min Lu Presented by: Mike Kraft Thanh Nguyen

2. Benchmarking  Commonly used bicycle frame measurements

4. Benchmarking  Commonly used bicycle frame measurements  21 – 23 inches for a European men’s racing bicycle  18.5 inches for a men’s mountain bicycle  Tubes of the frames are made of steel, aluminum alloys, titanium, carbon fiber.  Target population: mountain bike for adult male

5. Template  Template was built using anthropometric data for an adult male.

6. Anthropometric Data

7. Template  Template was built using anthropometric data for an adult male.  The template was scaled by a factor of 1/2

8. Beam Model  Used for design iterations  It was expected that Beam Model is the best choice for FEA analysis  3D beam element was used  Aluminum alloy 2024-T4 was chosen Young’s Modulus: 10.6 x 10 6 psi Yield Strength: 47,000 psi Poisson ratio : 0.33  Factor of Safety: 3

9. Beam Model – Pre Processing

10. Beam Model – Loading Calculations  Design iterations were performed on 3 different load cases: 200lbf load concentrated on the seat, pedal, and handle bar 1. A tube size was chosen 2. Apply load at the desired location 3. Obtain deflection result from ANSYS 4. Calculate frame stiffness, k frame 5. Calculate equivalent stiffness, k eq 6. Calculate static deflection, δ st 7. Calculate DAF and Dynamic Load 8. Apply dynamic load and obtain maximum bending moment and stress from ANSYS  Calculations were repeated for different tube size in order to find the optimal tube size for the design

11. Conclusion  Optimal tube size: 1”OD x 0.75” ID  Max Bending Stress with FOS = 3: Seat: 38,745 psi Pedal: 12,377 psi Handle Bars: 6,886 psi  Max Bending Stresses for all three load cases are less than the yield stress (47,000 psi)

12. Choosing the Best Design Final Design Stress Analysis Mesh Analysis Solid Model Shell Model Beam Model

13. Solid Modeling  High stiffness value, k  May result in under performance  Analyzes the volume of the structure Surface Modeling  Low stiffness value, k  May result in over designing structure  Analyzes the surface area of the structure

14. Meshing of Solid and Shell

15. Solid Modeling Stress Analysis Solid modeling meshes the volume of the model Maximum stress: 61,075 psi

16. Surface Modeling Stress Analysis Surface modeling meshes the surface area of the model Maximum stress: 124,725 psi

17. Maximum Stress Analysis SeatPedalsHandle Bars o Applied force at the seat yields the highest stress o Beams with stress above the maximum allowable

18. Final Design  Beam method  Isolate greatest maximum stress  Choose beam size to lower stress as necessary  Three beam sizes necessary 1” O.D. with 1/8” Wall 5/8” O.D. with 1/16 Wall 1/2” O.D. with 1/16” Wall

19. Final Design Stress Analysis