Team UDFSAE: Suspension Group David Zipf, Doug Corley, Josh Akell Faculty Advisor: Dr. Steve Timmins Sponsor: Jamie Gil Master Machinist: Steve Beard, Jeff Rickets Project Scope To design and fabricate all suspension components, including the front and rear A-arms, uprights, front hubs, mounting points, push rods and rockers, tie rods, spring and shock locations, control arm clevises, sway bar system and steering rods. Suspension must conform to FSAE rules and have wide range of adjustability Problem Background Formula SAE® is a student design competition organized by SAE International (formerly Society of Automotive Engineers). Concept is that a fictional manufacturing company has contracted a design team to develop a small Formula-style race car. Target marketing group for the race car is the non-professional weekend autocross racer. Student team designs, builds and tests a prototype based on a series of rules to ensure safe operation and clever problem solving. Glossary of Terms Front Suspension Rear Suspension Design Detail Evaluated and optimized using kinematic and force analysis. Measures of performance include bump steer and roll center movement. Designed to undergo forces seen in a combination of hitting a bump, braking, and cornering (5G vertical and 5G towards center of car, simulates extreme combined bump and corner loads). Adjustability in the wheel rate and spring rate was critical and can be adjusted by changing the sway bars’ pickup points. FBD of forces in suspension FEA of rocker Sketch of steering arms Mounting Upright Clevis Changed from steel to aluminum mounts, halved weight. Rear includes integrated toe link mount Chassis Clevis Bolted on steel. Shims allow alignment changes without removal of wheel. Camber, caster, and KPA can be adjusted this way Pushrods Made from welded steel. Designed to withstand combined 5G bump impact and cornering load Front Pushrod Mount Rear Pushrod Mount Key Metrics and Targets Metric Target Value Wheel Base 60” Spring Rate ~ 350 lbs./in (adjustable) Track Width 50” (front/rear) Dynamic Wheel Travel 2.0” Minimum Turning Circle ⌀ 20 feet Camber -1.5° (static), minimal gain Ease of Camber/Toe Adjustment Adjustment w/o removal of wheel/hub Scrub Radius 0.5” Roll Center High as possible without causing jacking. Bump Steer ≤ 1/16”/inch vertical deflection Cost < $1000 Caster Angle 4° Ride Height 2.5” from lowest point of car System Weight <30 lbs/corner with wheel & tire