Formula SAE Senior Project: Designing Major Components of a Weekend Racecar

1. Formula 1 Formula 1 Group Members: Group Members: Quinn Collett Quinn Collett Steve Godlewski Steve Godlewski Tobiah Halter Tobiah Halter Jeff Swanson Jeff Swanson Academic Advisor: Academic Advisor: Dr. Chien Wern Dr. Chien Wern June 4, 2003 June 4, 2003

2. Introduction Introduction Formula SAE is a competition focused on the design and fabrication of an affordable, weekend racecar. Performance and reliability are necessary attributes. Formula SAE is a competition focused on the design and fabrication of an affordable, weekend racecar. Performance and reliability are necessary attributes. As a Senior Project group we chose to design three major components of the car. As a Senior Project group we chose to design three major components of the car.

3. Project Scope Project Scope Design, fabrication and testing of the three design components: Design, fabrication and testing of the three design components: Hub Assemblies Hub Assemblies Drivetrain Drivetrain Aerodynamics Aerodynamics

4. Decision Process Decision Process Product Design Specifications Product Design Specifications External Search External Search Internal Search Internal Search Concept Evaluation Concept Evaluation

5. Presentation Outline Presentation Outline Rear Hub and Upright Design Rear Hub and Upright Design Front Hub and Upright Design Front Hub and Upright Design Differential Housing and Drivetrain Design Differential Housing and Drivetrain Design Aerodynamics Design Aerodynamics Design

6. Rear Hub and Upright Design Rear Hub and Upright Design

7. Components Components Bearing Housing Bearing Housing Flanges Flanges Connection Points Connection Points Angle Bracket Angle Bracket Bearings Bearings Fasteners Fasteners

8. Analysis of Hub Analysis of Hub Material: 6061-T6 Aluminum Material: 6061-T6 Aluminum Yield Strength: 40 ksi Yield Strength: 40 ksi Factor of Safety: 3 Factor of Safety: 3 Design Stress: 13.3 ksi Design Stress: 13.3 ksi Results of FEA Analysis: Results of FEA Analysis: Max Von Mises Stress: 14.5 ksi Max Von Mises Stress: 14.5 ksi Maximum Displacement: 0.002 in Maximum Displacement: 0.002 in

9. Analysis of Upright Analysis of Upright Material: 6061-T6 Aluminum Material: 6061-T6 Aluminum Yield Strength: 40 ksi Yield Strength: 40 ksi Factor of Safety: 3 Factor of Safety: 3 Design Stress: 13.3 ksi Design Stress: 13.3 ksi Results of FEA Analysis Results of FEA Analysis Max stress: 16.3 ksi Max stress: 16.3 ksi Max Deflection: 0.004 in Max Deflection: 0.004 in

10. Verification Verification PDS Criteria PDS Criteria Weight : Weight : The hub assembly will weigh less than 17 lbs. The hub assembly will weigh less than 17 lbs. Hub=2.5 lb, Upright=4.5 lb, Total = 7 lb Hub=2.5 lb, Upright=4.5 lb, Total = 7 lb Size/shape : Size/shape : Components will fit within an 13 inch wheel. Components will fit within an 13 inch wheel. It does fit. It does fit. Maintenance : Maintenance : 2 hour yearly overhaul 2 hour yearly overhaul Maintenance free: sealed bearings, locktite on all screws Maintenance free: sealed bearings, locktite on all screws Installation : Installation : Install in less than 120 min. Install in less than 120 min. Can be done inside of an hour: press in bearings, 3 bolts per side Can be done inside of an hour: press in bearings, 3 bolts per side Cost (materials, bearings, bolts): Cost (materials, bearings, bolts): less than $400 less than $400 Housing: $54.00, Hub: $186.94, Flange: $65.20, Connectors: $50.54, Housing: $54.00, Hub: $186.94, Flange: $65.20, Connectors: $50.54, Angles: $1.34, Fasteners: $8.61, Bearings: $18.80 Angles: $1.34, Fasteners: $8.61, Bearings: $18.80 Total Cost of Materials: $385.43 Total Cost of Materials: $385.43 Dynamic Testing Dynamic Testing Has performed properly to this point Has performed properly to this point

11. Front Hub/Upright Front Hub/Upright Design Criteria Design Criteria PDS PDS 30%-40% weight reduction over last years car 30%-40% weight reduction over last years car Ideal weight of 14 lbs. Ideal weight of 14 lbs. Assembly fit within a 13 in. dia. Wheel Assembly fit within a 13 in. dia. Wheel Handle loadings in race conditions Handle loadings in race conditions Incorporate connecting points for suspension and steering systems Incorporate connecting points for suspension and steering systems Component Selection Component Selection Suspension Geometry Suspension Geometry Steering Positioning Steering Positioning Brake Components Brake Components Bearing Selection Bearing Selection

12. Front Hub/Upright Front Hub/Upright Analysis Analysis Calculations Calculations Track Conditions Track Conditions Top speeds 60 mph/ Avg. Speed 30 mph Top speeds 60 mph/ Avg. Speed 30 mph Safety Factors Safety Factors

13. Front Hub/Upright Front Hub/Upright Components Components Hub assembly Hub assembly Two piece design for ease of maintenance Two piece design for ease of maintenance Double row angular contact bearing ( axial and radial loads) Double row angular contact bearing ( axial and radial loads) Upright Upright Spindle Spindle Modeled using Solidworks Modeled using Solidworks Used to ensure fit Used to ensure fit Compatibility with other components Compatibility with other components Clearances and interference Clearances and interference

14. Front Hub/Upright Front Hub/Upright Materials Materials 6061-T6 Aluminum 6061-T6 Aluminum 304 Stainless Steel 304 Stainless Steel Manufacturing Manufacturing CNC Mill CNC Mill Lathe Lathe Press Press

15. Front Hub/Upright Front Hub/Upright Verification Verification Weight Weight Last years 32 lbs. This year 11.4 lbs. Last years 32 lbs. This year 11.4 lbs. 64% weight reduction 64% weight reduction Under Ideal weight of 14 lbs. Under Ideal weight of 14 lbs. Track testing Track testing Handles loads under acceleration, deceleration, and cornering Handles loads under acceleration, deceleration, and cornering Problems/Improvements Problems/Improvements Two Piece Separation Two Piece Separation Spacers Spacers Further Advanced Optimization Further Advanced Optimization Weight reduction Weight reduction Cost reduction Cost reduction

16. Drivetrain Drivetrain Use of Common Parts Use of Common Parts Honda CBR 600 F1 Honda CBR 600 F1 Limited Slip Differential Limited Slip Differential Use of Common Materials Use of Common Materials 4140 Steel 4140 Steel 6061-T6 Aluminum 6061-T6 Aluminum

17. Rear Differential Rear Differential Aluminum Housing Aluminum Housing Zexel Torsen Limited Slip Differential Zexel Torsen Limited Slip Differential Sealed Bearings Sealed Bearings Retain Gear Oil Retain Gear Oil Check Valve Check Valve Roll-Over and Tilt Protection Roll-Over and Tilt Protection

18. Power Transmission Power Transmission Axle Shafts Axle Shafts 4140-3/4 Steel 4140-3/4 Steel U-Joints U-Joints Drive Shaft Drive Shaft Splined Drive Splined Drive Chain and Sprocket Chain and Sprocket Rear Mono-Brake Rear Mono-Brake

19. Drive Train Verification Drive Train Verification Performance Performance Dyno-Testinig Dyno-Testinig Road Testing Road Testing Weight Weight Target 50 lbs Target 50 lbs Manufacturing Time Manufacturing Time Target 15 hours Target 15 hours Production Cost Production Cost Target $2000 Target $2000 Failures Failures Drive Axle Welds Shielded Bearings Changes? Changes?

20. A A c c c c e e l l e e r r a a t t i i o o n n T T o o r r s s i i o o n n T T e e s s t t i i n n g g

21. Aerodynamics & Body Aerodynamics & Body Modeled using 3-D software package, SOLIDWORKS Modeled using 3-D software package, SOLIDWORKS Forms CNC machined Forms CNC machined Allowed for precision forming and exact fit Allowed for precision forming and exact fit Material: 1/8 fiberglass mat w/ fine mat finish Material: 1/8 fiberglass mat w/ fine mat finish Light weight and durable Light weight and durable Total Weight: 8.5 lbs. Total Weight: 8.5 lbs. Significantly below PDS target Significantly below PDS target

22. Body & Aerodynamics cont Body & Aerodynamics cont Estimated drag coefficient (C D ), front lift coefficient (C L ), drag force (D) and lift force (L) Estimated drag coefficient (C D ), front lift coefficient (C L ), drag force (D) and lift force (L) C D = 0.14 D = 1.950 lbf C L = 0.15 L = 0.910 lbf 1992 SAE

23. Body & Aerodynamics cont Body & Aerodynamics cont Estimated skin drag coefficient (C F ) and surface shear force per unit surface area ( ) (friction resistance) Estimated skin drag coefficient (C F ) and surface shear force per unit surface area ( ) (friction resistance) C F = 4000 = 901.87 lbf/ft 2 Source: Race Car Engineering , Katz

24. Body & Aerodynamics cont Body & Aerodynamics cont Overall Performance Evaluation Overall Performance Evaluation Overall weight of car significantly minimized Overall weight of car significantly minimized PDS projected weight = 30 lb PDS projected weight = 30 lb Actual weight = 8.5 lb Actual weight = 8.5 lb Dimensions of car w/in 2% of desired Dimensions of car w/in 2% of desired Drag force minimized as specified in PDS Drag force minimized as specified in PDS Typical F-1 C D = 1.07 Typical F-1 C D = 1.07 PSU Formula C D = 0.015 PSU Formula C D = 0.015 Lift force acceptable but could be further minimized by introducing further down force components which were sacrificed to make room for critical components (i.e. intake apparatus, radiator) Lift force acceptable but could be further minimized by introducing further down force components which were sacrificed to make room for critical components (i.e. intake apparatus, radiator) Typical F-1 C L = -0.99 Typical F-1 C L = -0.99 PSU Formula C L = 0.015 PSU Formula C L = 0.015 Cooling performance maximized by channeling air over water-cooled components Cooling performance maximized by channeling air over water-cooled components average engine temperature w/o channeled air over radiator = 220 F average engine temperature w/o channeled air over radiator = 220 F average engine temperature w/ channeled air over radiator = 200F average engine temperature w/ channeled air over radiator = 200F

25. Performance in Action Performance in Action