•Faculty Advisor• Abdelmageed Elmustafa

•GROUP MEMBERS:•JOHN MERRITT

•FRANCES OTHERSEN•CHRISTOPHER DAVIS

•JAMES CHAPMAN•JOSEPH FANNING

Baja SAE

Objective

● Purpose: Design and build an off road vehicle to meet the specifications of the SAE Baja competition.● Tasks: A. Redesign a rear suspension design that uses traditional

trailing links that can later incorporate passive rear steer.

B. 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.

Work Breakdown

● Gearbox Members:

○ John Merritt

• Overall team leader

• Lead Design

○ Frances Othersen• Analytical testing• Scribe

○ James ChapmanDesign/Material Selection

●Suspension Members:

○ Chris Davis• Analytical Testing• Scribe

○ Joseph Fanning• Lead design

Gantt Chart

Analysis was performed for frame

using three different loadings:

1. Frontal impact with another car or

part of course (3000 lbs)

2. Frontal rollover, roof takes force

(2400 lbs)

3. Side Impact / Rollover (2000 lbs)

Maximum Stress Observed: 64.2 ksi

Maximum Deflection Observed: 1.78

inches

Frame Analysis

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:

18.07 in x 4.55 in x 12 in

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

Gearbox Analytical Test

Gear 5:Maximum Stress Observed: 1094 psiMaximum Deflection Observed: 2.209e-005 in

Gear 6:Maximum Stress Observed: 775 psiMaximum Deflection Observed: 3.354e-005 in

Yield Stress: 89984.6 psiTensile Strength: 104982 psi

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

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

Rear Swing Arm Analysis

Analytical Test SolidWorksAnalytical Test SolidWorks

Patran:Maximum stress observed: 1530 psiMaximum deformation observed: 6.94e-001 in

SolidWorks:Maximum stress observed: 518 psiMaximum deformation observed: 2.54e-003 in

Deformation and stress analysis without shock absorbers

Future Work

• Assembly

• Test Driving

• Performance Tuning

• Final Adjustments

Any Questions?