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

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.

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

Gantt Chart

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

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 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: 89984.6 psi Tensile 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 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

Future Work Assembly Test Driving Performance Tuning Final Adjustments

Any Questions?