OFFROAD INNOVATIONS Design of an OffRoad Front Suspension

OFF-ROAD INNOVATIONS Design of an Off-Road Front Suspension and Steering System GROUP M 2: ANDREW SNELGROVE CALVIN HOLLOWAY JEREMY SHEPHERD KATE PRICE

Outline • • • The SAE Baja Competition Problem Definition The Current System Suspension System Validation Steering System Validation Design Methodology Design Targets Moving Forward Management Plan

The SAE Baja Competition The Baja SAE Series is an international competition testing the limits of off-road vehicles designed and built by engineering students from around 100 universities each year.

Introduction to SAE Baja Competition Suspension and Traction

Introduction to SAE Baja Competition Rock Crawl Mud Pit

Introduction to SAE Baja Competition Design Competition

Problem Definition Off-Road Innovations’ goal is to develop a front suspension and steering system for the Memorial Baja team that will: • • Provide more driver room Improve ground clearance Absorb frontal impact forces Maintain safety, reliability and low weight

The Previous System 2013 Memorial Baja Steering 2013 Memorial Baja Suspension

Steering System Validation Manual Rack and Pinion Pro: Lightweight and Robust Con: More Effort to Steer

Steering System Validation Recirculating Ball Gearbox with Pitman Arm Pro: Less Effort to Steer Con: Complicated and no driver feedback

Steering System Validation Electric Power-Assisted Hydraulic Power-Assisted Pro: Less Effort to Steer Con: Complicated and Heavy

Steering System Validation Rack and Pinion Recirculating Ball Gear Hydraulic Power-Assisted Electric Power-Assisted Criteria Score Weighted Score Score Cost (0. 1) 5 1 4 0. 8 2 0. 4 Weight (0. 2) 5 1. 5 4. 5 1. 35 1. 5 0. 45 4 1. 2 Manufacturability (0. 2) 4 0. 8 2. 5 0. 1 1. 5 0. 3 Performance (0. 35) 2. 5 0. 375 3. 5 0. 525 Maintenance (0. 1) 4 0. 6 3. 5 0. 525 1 0. 15 2 0. 3 Weighted Total 4. 275 3. 55 1. 625 Final Selection: Rack and Pinion 2. 725

Suspension System Validation Swing Axle Pro: Robust Con: Heavy Double A-arm Pro: Large Motion Range Con: Complexity

Suspension System Validation Trailing Arms Pro: Compact Con: Difficult Mounting Mac. Pherson Strut Pro: Simplistic Con: Limited Range

Suspension System Validation Swing Axle Criteria Score Double A-arms Mac. Pherson Strut Trailing Link Weighted Score Score Cost (0. 1) 1 0. 1 2 0. 2 4 0. 4 Durability (0. 2) 4 0. 8 5 1 3 0. 6 2 0. 4 Weight (0. 2) 4 0. 8 3 0. 6 4 0. 8 Manufacturability (0. 15) 2 0. 3 5 0. 75 2 0. 3 1 0. 15 Performance (0. 35) 2 0. 7 5 1. 75 3 1. 05 1 0. 35 Maintenance (0. 1) 3 0. 3 4 0. 4 2 0. 2 4 0. 4 Weighted Total 3 4. 9 2. 95 Final Selection: Double A-arms 2. 5

Design Methodology

Design Methodology Track Wheelbase Ackerman Steering

Design Targets Design Parameters Previous Value Design Target Static Camber Change Steering Axis Inclination Scrub Radius Static Toe Change (over travel) Static Caster Angle Caster Change (over travel) Track Wheel Base Static Ride Height Vertical Wheel Travel (Jounce) Vertical Wheel Travel (Rebound) Recessional Travel Unsprung Weight -4 deg -6 deg 8 deg 30 mm 0 deg 3 deg 0 deg 1350 mm 1558 mm 230 mm 152. 4 mm 100 mm 0 mm 16. 5 Kg -4 deg -6 deg 8 deg 30 mm 0 deg 6 deg 0 deg 1350 mm 1450 mm 281 mm 200 mm 100 mm 51 mm 16. 5 Kg Clarification Leans into Turns Improves Handling Raising Ground Clearance Shock Compression Absorbs Frontal Impact

Moving Forward Next steps include: • Finalizing geometry • Generating Models • Simulation and FEA

Management Plan To mitigate the risks to driver safety and project completion: • Closely follow SAE standards for the Baja SAE series • Monitoring progress with respect to planned milestones

References http: //www. uniquecarsandparts. com. au/how_it_works_steering. htm http: //image. absoluteastronomy. com/images/encyclopediaimage s/a/ac/ackermann. svg. png http: //forums. bajasae. net/forum/caster_topic 1126. html http: //www. subaruofkeene. com/specials/service. htm http: //www. townfairtire. com/wheel-alignment/caster-camberand-toe-alignments/

Questions? More information is also available at: www. Off. Road. Innovations. weebly. com