1. SAE Baja Senior Design Project
Midterm Presentation
Suspension
Peter Morabito
Michael Paliga
Brian Ross
Drivetrain
Kenny Elliot
Patrick Mooney
Dylan Quinn
Frame
Dan D’Amico
Curtis May
Greg Schafran

2. To design a vehicle for the SAE Baja Competition
Introduction
Objective:
To design a vehicle for the SAE Baja Competition
Competition Events
Acceleration
Hill Climb
Mud Bog
Endurance
Maneuverability

3. Drivetrain Engine CVT Gearbox 14.50 ft lbs of Torque ~10 horsepower
Gaged GX-9 CVT specifically designed for SAE Baja
3.85:1 initial ratio
0.9:1 final ratio
Gearbox
Double Reduction Gearbox
8:1 Ratio

4. Barth Velocity Factor of Safety AISI 1020 Steel Safety factor
Gear Design- Methods
Our calculations were based on methods found in Shigley’s Design manual.
Gear Ratio Calculations
Safety Factor Calculations
[Veh. wt]*[Sin(incline angle)] = Repelling Weight
[650 lbs]*[Sin(40 degrees)] = 418 lbs
Rep wt = (tire rad)*(CVT ratio)*(engine tq)*(X min)
418 lbs = (1.0 ft)*(3.85)*(14 lb-ft)*(X min)
----->Xmin=
Gear Ratio: (8.0/7.7551) =
Vehicle Weight: (650 lbs / 600 lbs) =
Incline Angle: (40 deg / 37.5 deg) =
Torque: (15 lb-ft max / 14 lb-ft avg) =
Total FS = (1.0326)(1.0833)(1.0667)(1.0714)
----->Total Safety Factor =
After determining the specific gear selections we also analyzed each gear for:
Face Width
Interference
Lewis Bending Stress
AGMA Stress and Strength
Barth Velocity Factor
Lewis Bending Stress
Barth Velocity Factor
Lewis Factor of Safety
Barth Velocity Factor of Safety
Stage
Pitch
Teeth
Pitch Angle Dp
Face Width
Tangential Load (lbf)
Lewis Form Factor
Stress (psi)
stress (psi)
AISI 1020 Steel Safety
AISI 1020 Steel Safety factor 1 12 20
1.6666
803.88
0.322
16.342
6.658 40
3.3333
0.389
9.871
4.021 2
7.782
4.505 80
6.6666
0.436
2.634
1.525

5. Gear Design- Results Two Stage Reduction Gearbox (8.0:1)
Size: 20/40 teeth
Pitch: 12
Face Width: 1.0 in
Stage :1
Size: 20/80 teeth
Pitch: 12
Face Width: 1.0 in
Gear Ratio: A minimum ratio of was
calculated and 8:1 chosen to provide extra torque
Top Speed: 35.7 MPH at 3600 RPM.
Face Width Required: 1.0 inches
Gear Material: AISI 1020
Total Safety Factor (torque output): 1.277
Lewis Safety Factor (minimum): 2.63
6.5 inch diameter output gear allows room for differential mounting and selection.

6. Differential What Comes Next?
This year’s more advanced design will incorporate a differential
Added to increase the vehicles maneuverability
Wheels will be able to rotate at different speeds
Better in technical events and in and out of tight turns
Will be a great help since the vehicle lacks reverse
Need to determine shaft size to fit differential
What Comes Next?
Gearbox housing and bearings
FEA analysis
Subframe/Mounting

7. Suspension Front Suspension Basic Double A-arm setup
Same overall design as previous years car
No significant changes, just modifying to fit newly designed frame
Rear Suspension
Using a rear trailing arm set up similar to the 2012 car
Eliminating the dynamic toe aspect, but maintaining the dynamic camber
Improving wheel travel and reliability

8. Shock Selection Fox Float Racing Shocks:
Adjustable air spring, velocity damping control, and light weight.
Reduced Cost - $ per pair versus $859 per pair for Custom Works Shocks.
Comparable performance

9. Optimum K Front suspension modeled in Solid Works
Front suspension modeled in Optimum K
Front suspension has begun testing in Optimum K

10. Frame- Methods
SAE standards
Firewall
Front end
Roll cage
Rear end

11. Frame- Analysis The 2012 ODU Mini Baja (55th place) weighed 479 pounds
Cornell’s car (3rd place) weighed only 306 pounds
Reduce frame size and weight
Eliminate redundant members

12. Frame- Results Material-4130 steel tubing Shorter overall length
Lighter than previous ODU cars
Future: FEA using PATRAN
Rollover
Test front/rear/ side impact

13. Gantt Chart

14. Questions?