Transcript Slide 1
Suspension •Peter Morabito •Michael Paliga •Brian Ross Drivetrain •Kenny Elliot •Patrick Mooney •Dylan Quinn Frame •Dan D’Amico •Curtis May •Greg Schafran To design a vehicle for the SAE Baja Competition 14.50 ft lbs of Torque ~10 horsepower •Gaged GX-9 CVT specifically designed for SAE Baja •3.85:1 initial ratio •0.9:1 final ratio •Double Reduction Gearbox •8:1 Ratio Gear Ratio Calculations Safety Factor Calculations [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 Stage Pitch Teeth Pitch Angle Dp Face Tangential Load Lewis Form Width (lbf) Factor Gear Ratio: (8.0/7.7551) = 1.0326 Vehicle Weight: (650 lbs / 600 lbs) = 1.0833 Incline Angle: (40 deg / 37.5 deg) = 1.0667 Torque: (15 lb-ft max / 14 lb-ft avg) = 1.0714 Total FS = (1.0326)(1.0833)(1.0667)(1.0714) ----->Total Safety Factor = 1.2772 Lewis Bending Stress Barth Velocity Factor Lewis Factor of Barth Velocity Factor Safety of Safety Stress (psi) stress (psi) AISI 1020 Steel AISI 1020 Steel Safety 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 Stage 1 - 2.0:1 Size: 20/40 teeth Pitch: 12 Face Width: 1.0 in Stage 2 - 4.0:1 Size: 20/80 teeth Pitch: 12 Face Width: 1.0 in 6.5 inch diameter output gear allows room for differential mounting and selection. Differential •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 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 Frame- Analysis • 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- Results Material-4130 steel tubing Shorter overall length Lighter than previous ODU cars Future: FEA using PATRAN Rollover Test front/rear/ side impact