2012-2013 wpi sae baja vehicle

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inglês - Documento sobre o projeto baja, detalhes de direção e construção do veiculo em geral

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  • 2012-2013 WPI SAE Baja Vehicle

    A Major Qualifying Project

    Submitted to the faculty of

    Worcester Polytechnic Institute

    in partial fulfillment of the requirements for the

    Degree of Bachelor of Science

    Submitted By:

    ______________________

    Christopher Boyle

    ______________________

    Raymond Casola

    ______________________

    James Tauby

    ______________________

    Jesse Taylor

    Approved By:

    ______________________

    David Planchard, Advisor

    Date: April 22, 2013

  • ii

    Abstract

    The Baja Society of Automotive Engineers (SAE) competition is held annually in order

    to provide engineering students an opportunity to design and build a competitive off-road

    vehicle. This Major Qualifying Project (MQP) focused primarily on a major redesign of a

    previous WPI Baja SAE car (2008-2009 Design and Fabrication of a SAE Baja Race Vehicle),

    by determining it strengths and weaknesses through design reviews and field-testing. The

    MQP improved the following subsystems, identified as the weakest components of the car:

    drivetrain, steering, brakes, and front suspension.

    The team removed the existing hybrid-hydraulic drivetrain and designed, fabricated

    and tested a new mechanical drivetrain. The steering geometry was designed according to

    the Ackerman principle and to balance the effects of caster and camber. The required

    braking force for the car was calculated, and a new front and rear braking system was

    installed with the ability to lock all four wheels at speed, as stated in the SAE rulebook.

    The front suspension was addressed to provide proper ground clearance in

    accordance with the SAE guidelines and to maximize suspension travel. New components

    and sub-systems were designed using SolidWorks. SolidWorks Simulation was used to

    perform finite element analysis to optimize each component and subsystem to determine

    the necessary strength while minimizing weight. Material selection was based on design

    factors including weight, cost, and performance.

    All work was performed in accordance with the SAE Baja guidelines to maintain the

    cars eligibility for competition.

  • iii

    Table of Contents

    Abstract ........................................................................................................................................... ii

    Table of Contents ........................................................................................................................... iii

    Table of Figures ............................................................................................................................. vi

    Introduction ..................................................................................................................................... 1

    Goals and Objectives ...................................................................................................................... 2

    Product Specifications .................................................................................................................... 3

    Drivetrain ........................................................................................................................................ 4

    Engine ......................................................................................................................................... 4

    Original 2009 Drivetrain ............................................................................................................. 6

    Drivetrain Design Goals ............................................................................................................. 8

    New Drivetrain Design ............................................................................................................... 9

    Drivetrain Manufacturing ......................................................................................................... 12

    Engine Mount Plate............................................................................................................... 12

    Bearing Plates ....................................................................................................................... 13

    Sprockets ............................................................................................................................... 16

    CVT (Continuously Variable Transmission) ............................................................................ 16

    CVT Shaft Support ................................................................................................................... 17

    Brakes ........................................................................................................................................... 19

    Original Brakes ......................................................................................................................... 19

  • iv

    Brake Design Goals .................................................................................................................. 21

    Brake Design ............................................................................................................................. 22

    Brake Testing ............................................................................................................................ 30

    Front Suspension ........................................................................................................................... 30

    Design Process .......................................................................................................................... 31

    Static Properties .................................................................................................................... 32

    Dynamic Properties ............................................................................................................... 33

    Original ..................................................................................................................................... 34

    New Suspension Design ........................................................................................................... 38

    Preliminary Design Parameters............................................................................................. 39

    Static Parameters ............................................................................................................... 39

    Dynamic Parameters ......................................................................................................... 40

    Control Arm Design .............................................................................................................. 41

    Knuckle Design ..................................................................................................................... 47

    Steering Design ..................................................................................................................... 49

    Assembly in SolidWorks .......................................................................................................... 52

    Finite Element Analysis ............................................................................................................ 55

    Manufacturing ........................................................................................................................... 62

    Control Arms ........................................................................................................................ 63

    Ball Joint Housing and Rod End Housing Machining ...................................................... 63

  • v

    Tube Notching and Fitting ................................................................................................ 65

    Welding ............................................................................................................................. 69

    Knuckle ................................................................................................................................. 71

    Machined Components ..................................................................................................... 72

    Welding ............................................................................................................................. 75

    Hub and Spindle Re-work ..................................................................................................... 77

    Testing....................................................................................................................................... 79

    Overall Results and Testing .......................................................................................................... 82

    Conclusion and Recommendations ............................................................................................... 83

    Works Cited .................................................................................................................................. 84

    Appendix ....................................................................................................................................... 85

  • vi

    Table of Figures

    Figure 1: Briggs and Stratton Power Curve .................................................................................... 5

    Figure 2: Real World Briggs and Stratton Power Curve ................................................................ 6

    Figure 3:

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