1. Abdelmageed Elmustafa
Baja SAE
Faculty Advisor
Abdelmageed Elmustafa
GROUP MEMBERS:
JOHN MERRITT
FRANCES OTHERSEN
CHRISTOPHER DAVIS
JAMES CHAPMAN
JOSEPH FANNING

2. Objective
Purpose: Design and build an off road vehicle to meet the specifications of the SAE Baja competition.
Tasks:
Redesign a rear suspension design that uses traditional trailing links that can later incorporate passive rear steer.
Design a two speed gearbox using spur gears.
Total Budget: $12,000
Projected Completion date: April 30, 2015
Goal: Place in the top ½ of competitors overall.

3. Work Breakdown Gearbox Members: Suspension Members: John Merritt
Overall team leader
Lead Design
Frances Othersen
Analytical testing
Scribe
James Chapman Design/Material Selection
Suspension Members:
Chris Davis
Analytical Testing
Scribe
Joseph Fanning
Lead design

4. Gantt Chart

5. Frame Analysis
Analysis was performed for frame using three different loadings:
Frontal impact with another car or part of course (3000 lbs)
Frontal rollover, roof takes force (2400 lbs)
Side Impact / Rollover (2000 lbs)
Maximum Stress Observed: 64.2 ksi
Maximum Deflection Observed: 1.78 inches

6. Two Speed Gearbox Initial Conditions for Calculations:
9.6 delivered horsepower
14 ft-lbf torque
987 rpm input speed, 115 rpm output speed
Moderate shock levels, occasionally high
Maximum gearbox size allowed: in x 4.55 in x 12 in

7. Two Speed Gearbox Calculated Results
Torque Ranges: 51 ft-lbf to 442 ft-lbf
Velocity Ranges: 350 ft/min to 540 ft/min
Transmitted Load Ranges: 590 lbf to 880 lbf
Safety Factor: n = 1.4
Gear Ratios:
8.66:1 and 11.2:1

8. Gearbox Analytical Test
Maximum Stress Observed: 1094 psi
Maximum Deflection Observed: 2.209e-005 in
Gear 6:
Maximum Stress Observed: 775 psi
Maximum Deflection Observed: 3.354e-005 in
Yield Stress: psi
Tensile Strength: psi

9. Initial Suspension Design
Initial rear-steer design pivots around z-axis, allowing it tow in/out of 1° to 3° degrees based on travel.
Advantages
Can be built to vehicle specifics
Can use any size bushing (Knuckle is designed based on bushing)
Increased maneuverability
Disadvantages
Cost (Materials, machining)
Not easy to fix/repair/adjust

10. Rear Suspension Traditional Trailing Arm
Traditional trailing arm design is similar to the passive rear steer, however does not pivot around z-axis.
Advantages:
Able to utilize many different hub assemblies
Easy to repair/adjust
Cheaper (Materials, machining)
Disadvantages:
Does not allow wheels to tow in/out
Less maneuverability

11. Rear Swing Arm Analysis
Analytical Test SolidWorks
Analytical Test SolidWorks
Patran:
Maximum stress observed: 1530 psi
Maximum deformation observed: 6.94e-001 in
SolidWorks:
Maximum stress observed: 518 psi
Maximum deformation observed: 2.54e-003 in
Deformation and stress analysis without shock absorbers

12. Future Work
Assembly
Test Driving
Performance Tuning
Final Adjustments

13. Any Questions?