1. Structural Integrity UNDERSTAND STRUCTURAL STRENGTH OF LOAD BEARING COMPONENTS IN MECHANICAL SYSTEM

2. Understand Solid Mechanics Most of what we’ll do here is covered in a Solid Mechanics Class ◦eCourses: http://ecourses.ou.edu/cgi-bin/navigation.cgi?course=mehttp://ecourses.ou.edu/cgi-bin/navigation.cgi?course=me Looking at: ◦Stress ◦Beams ◦Deflection ◦Failure ◦Boundary Conditions ◦Simple Finite Element Analysis

3. Steps to Weldments See video tutorials on Green-Tricycle.com Create 3D Sketch in SolidWorks Apply Weldment Cross Section ◦Show Weldments Tab (not visible by default) Trim as necessary Provides a cut list for frame manufacturer Joints automatically created for Finite Element Analysis

4. Our Green Tricycle Steel frame design (Weldments in SolidWorks) Has to endure static loading (rider + attachments + payload) Has to ensure other loading (impacts, drops, etc…) Use SolidWorks for Analysis (Beam Elements) See videos on Green-Tricycle.com for more

5. Can You Validate FEA? YES. “By Hand”! Use this Example for a cantilever beam Deflection=(P*L 3 )/(3*E*I) ◦P = 500 lb ◦L=8 in ◦a=0.5 in ◦b=2 in E = 30457924.9 psi I=(a 3 *b)/12

6. Results Apply fixed “boundary condition” Apply load at opposite end Mesh & Run Analysis SolidWorks Displacement = 0.1329 in Hand Displacement = 0.135 in Reasonably close (1.35% Difference).

7. Finite Element Analysis in SolidWorks See provided videos above this presentation or at Green-Tricycle.com

8. Results of Our Analysis Analysis 1: ◦Applied a 250 lb load at center seat bar (expected weight of the rider and a payload) ◦Load is applied vertically downward to the location of the seat ◦Frame fixed at three points: ◦Mounting points for the front wheels and the fork tube in the rear. ◦Frame is plain carbon steel. Yields: 39,890 psi Results: ◦The highest stress: ~5,600 psi ◦The MAX deflection: ~0.04 in ◦Directly below the seat.

9. Results of Our Analysis Analysis 2: ◦Applied peak load from the speed bump simulations (front wheels experienced 500 lbf each) ◦Load is applied vertically upward to the location of the wheel bearings ◦Frame fixed at one point: ◦Seat Post Tube. ◦Frame is plain carbon steel. Yields: 39,890 psi Results: ◦The highest stress: ~26,600 psi ◦The MAX deflection: ~0.06 in