Suspension Peter Morabito Michael Paliga Brian Ross Drivetrain Kenny Elliot Patrick Mooney Dylan Quinn Frame Dan DAmico Curtis May Greg Schafran.

SAE Baja Senior Design Project

Suspension•Peter Morabito•Michael Paliga•Brian Ross

Drivetrain•Kenny Elliot•Patrick Mooney•Dylan Quinn

Frame•Dan D’Amico•Curtis May•Greg Schafran

Midterm Presentation

IntroductionObjective: To design a vehicle for the SAE Baja Competition

Competition EventsAcceleration Hill Climb Mud Bog

ManeuverabilityEndurance

Drivetrain

Engine 14.50 ft lbs of Torque~10 horsepower

CVT •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

Gear Design- MethodsOur calculations were based on methods found in Shigley’s Design manual.

[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= 7.7551

Gear Ratio CalculationsGear Ratio: (8.0/7.7551) = 1.0326Vehicle Weight: (650 lbs / 600 lbs) = 1.0833Incline Angle: (40 deg / 37.5 deg) = 1.0667Torque: (15 lb-ft max / 14 lb-ft avg) = 1.0714Total FS = (1.0326)(1.0833)(1.0667)(1.0714) ----->Total Safety Factor = 1.2772

Safety Factor Calculations

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

WidthTangential Load

(lbf)Lewis Form

Factor Stress (psi) stress (psi) AISI 1020 Steel Safety

AISI 1020 Steel Safety factor

1 12 20 20 1.6666 1 803.88 0.322 4160.869 10212.609 16.342 6.658

1 12 40 20 3.3333 1 803.88 0.389 6888.431 16907.249 9.871 4.021

2 12 20 20 1.6666 1 1688.148 0.322 8737.826 15092.152 7.782 4.505

2 12 80 20 6.6666 1 1688.148 0.436 25812.660 44584.157 2.634 1.525

Gear Design- Results

Gear Ratio: A minimum ratio of 7.7551 wascalculated 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

Stage 1 - 2.0:1Size: 20/40 teeth Pitch: 12Face Width: 1.0 in

Stage 2 - 4.0:1Size: 20/80 teeth Pitch: 12Face Width: 1.0 in

Two Stage Reduction Gearbox (8.0:1)

6.5 inch diameter output gear allows room for differential mounting and selection.

•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

Differential

What Comes Next?

•Gearbox housing and bearings•FEA analysis •Subframe/Mounting

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

Shock Selection

Fox Float Racing Shocks: Adjustable air spring, velocity damping control, and light weight. Reduced Cost - $521.25 per pair versus $859 per pair for Custom Works

Shocks. Comparable performance

Optimum K

• Front suspension modeled in Solid Works

• Front suspension modeled in Optimum K

• Front suspension has begun testing in Optimum K

Frame- Methods•SAE standards•Firewall•Front end•Roll cage•Rear end

• 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

Frame- Analysis

Material-4130 steel tubing

Shorter overall length

Lighter than previous ODU cars

Future: FEA using PATRAN

Rollover

Test front/rear/ side impact

Frame- Results

Gantt Chart

Questions?