FLORIDA INSTITUTE OF TECHNOLOGY COLLEGE OF ENGINEERING Design Presentation Project: 2007 R.E.V. Team Presented By: Elizabeth Diaz Jason Miner Jared Doescher Josh Wales Kathy Murray AJ Nick Dave Wickers Oliver Zimmerman Project Scope: • Design and Build an electric racing vehicle • Promote community awareness of electric vehicles •Electric Car designed to compete in SCCA Autocross and Formula Hybrid competition - Competing as “Hybrid-in-Progress” vehicle for one year only - Electric Car designed to compete in Autocross, Acceleration and Endurance races •Will meet requirements for the 2007 Formula Hybrid competition and NEDRA race competition Engineering Objectives: • Acceleration from 0 to 60 mph in under 5 seconds • Top speed of 80 mph • Maximum power available between 20 and 40 mph • Lightweight (under 650lb without driver) • 15 minute battery life for continuous draw Team Organization: Team Lead Development Group Procurement Group Manufacturing Group Integration Team Design Teams Chassis & Body Vehicle Dynamics Driver Interface & Ergonomics Drive System Electrical Chassis Redesign Suspension System Cockpit Design Motor Battery Management Body Redesign Steering System Safety Equipment Drivetrain Instrumentation Mounting Points Braking System Driver Interface Control System Data Transfer System Aeros/Ground Effects Battery System Power Management Cooling System Shielding System Team Organization: REV Design Teams Team Lead: Elizabeth Diaz Design Teams Drive System Team: Vehicle Dynamics Team: Chassis & Body Team: Josh Wales Jason Miner Jason Miner AJ Nick AJ Nick Dave Wickers Kathy Murray Dave Wickers AJ Nick Jared Doescher Kathy Murray Electrical Team: Driver Interface Team: Matt Reedy Oliver Zimmerman Valerie Bastien Dave Wickers Audrey Moyers Kristi Harrell Major Goals of the Team • Complete the car • Create/Integrate Lithium-Ion pack • More publicity – Autocross racing – More EV events – Local advertising • Funding Florida Tech REV • Overall Length, Width, Height: 107in x 60in x 46in • Wheelbase: 68.5in • Front Track: 52in • Rear Track: 50in • Weight: 795lbs (without driver) Design: Chassis Engineering Specifications • Static deflection – Less than .333” • Torsional Rigidity – above -1500 ft-lbs/deg • Wheelbase – between 60” and 70” • Designed to fit 95 percentile person • Withstand stresses under dynamic and static loading with factor of safety of 3 Design: Chassis • Side Pods act as impact structure • Upper side impact structure member attached too high to main hoop • As requested by Formula Hybrid, new cross member had to be constructed to protect driver Static Analysis Deflection Analysis Static Stress Analysis Max deflection: -.0098 inches Max stress: 5361 psi Factor of safety:11.9 Dynamic Stress Analysis • Using MSC ADAMS to get forces at A-Arm attachments •Braking ( 60- 0 in 3 sec) •Lane change at 50 mph •60 mph radius turn of 343 feet •Applied loads in ANSYS to find stress Braking Cornering Max stress: 22126 psi Max stress: 16159 psi Analysis Changes: Chassis Torsional Rigidity Analysis •Constrained back of frame and added forces to front hoop •Measured deflection at nodes on hoop •Calculated Torsional rigidity by: 4900 ft/lbs per degree Manufacturing: Chassis • Frame was constructed on campus • Weld analysis proved welds will hold • Intersections with many multiple welds were hardest to cope Lessons Learned: Chassis • Have more than one designer on the chassis • Design and analysis together • Consideration of weight versus strength Suspension Design • Allow 1” travel jounce and rebound • Achieve maximum tire contact at all times • Optimize handling • Non-equal, Non-parallel A-arms • Push rod actuated coil-overs • Variable dampers Suspension Design Specifications Table 3.7: Front Suspension Geometry Table 3.8: Rear Suspension Geometry Static Camber -1.5˚ Static Camber 0˚ Camber Gain in Jounce -.95˚/1" Camber Gain in Jounce -1.05˚/1" Camber Gain in Rebound .89˚/1" Camber Gain in Rebound 1.02˚/1" Caster 5˚ Caster 3˚ Kingpin Offset .915" Kingpin Offset 0.02" Kingpin Inclination 0˚ Kingpin Inclination 0˚ Toe In 0˚ Toe In 1˚ Ground Clearance 2" Ground Clearance 2" Static Roll Center 1.23" Static Roll Center 1.34" Roll Center @ 1" Jounce -.18" Roll Center @ 1" Jounce 0.4" Roll Center @ 1" Rebound 2.65" Roll Center @ 1" Rebound 2.75" Front Track Width 52" Rear Track Width 50" Front Suspension BELLCRANK POSITION CHANGE FOR CLEARANCE ISSUES Rear Suspension COILOVER ACTUATION DESIGN COILOVER ACTUATION BUILD Suspension Adjustability Shims between clevis Roll Center Suspension Spring Rates FRONT SPRING RATE ≈ 350 LB/IN REAR SPRING RATE ≈ 372 LB/IN Dampers • Nitrogen Charged • Adjustable damping in jounce and rebound • Preload adjustment • Cost effective Jupiter 5 by Risse Racing Steering Geometry • Rack and Pinion • Lower rear placement • Full Ackermann geometry Testing and Improvements • Final car setup and fine tuning – Ride Height – Camber – Toe • Add anti-roll bars • Add sensors Lessons Learned: Suspension • Check more thoroughly for clearance issues • Use proper bolts • Change clevis design Design: Differential • Brute Force Kawasaki ATV front differential • Limited Slip with a selectable locker • 4.375 gear reduction Differential & Mounting •Tensile Yield Stress of Aluminum: 47000 psi •3/8” thick aluminum •Max Von Mises stress: 33665 psi •Factor of safety of 1.3 Differential & Mounting •Instead of remanufacturing with 1/2” aluminum an additional mount was added •Max Von Mises stress: 25944 psi •Factor of Safety of 1.8 Design: Electrical Integration • Warp 9” motor, 80hp peak, 140ft-lbs • 32.3 continuous horsepower (versatile) • 600amps, 144volts from Zilla 1K-HV (with power conversion) • 2 min full throttle run time, 15min at 35mph • Top Speed 85mph @ 6000 rpm • Pic to PLC to LCD Power Source & Containment Area • Lead Acid Batteries 232lbs, 13.6 usable Ah (17ah, up to 80% discharge) at 192V (Nominal) • 16 cells, cost approx. $1500 • Odyssey PC680 Lead-acid batteries • Diagonal Support tube thickness increased to .095” (full X) • Battery Layout Strapped together then strapped to supports Plexiglas to cover connections (with High Voltage Warning Label) Odyssey Battery, Nomex fabric on walls and bottom for Model PC680 electrical insulation and fire protection Power Source & Containment Area • Full High Voltage Accumulator Containment Dual Contactors default to Open 3 Emergency Stop Buttons Fuse Backup High power lines outside Battery Area held in rubberized conduit Ferraz-Shawmut Albright SW200 Fuse contactor Design: Performance Calcs • Motor, Battery, gear ratio combination was essential decision. • Excel Spreadsheet used to compare and optimize. • Takes into account specs and calculates 0-60 time, voltage drop, runtime, and more. • Final Configuration: 0-60mph in 4.5 seconds (calculated) Design: Brakes • Design Criteria – Braking system that acts on all four wheels and is operated by single control – Two independent hydraulic circuits • Alterations in Design – New master cylinders were purchased due to a leak in the old ones Design: Brakes • Design Calculations – To optimize handling the front wheels should lock up first in a full braking situation • To ensure this a bias was applied to master cylinders – Front 60% and rear 40% – Full Braking from 60 mph • Calculated stopping distance: 124.73 ft Design Changes: Steering Wheel Previous Design • Design Criteria – Must be able to hold the touch screen – Comply with SAE rules – Designed to be as light as possible while remaining rigid enough to protect touch screen Current Design – Shaped for driver’s comfort • Alterations in Design – Changed because of the method of mounting provided from manufacturer – Created a new wheel to be fully closed loop IAW SAE rules Design Changes: Steering Wheel • Design Criteria – Structurally Rigid and Reliable • Previous Steering Wheel did not fit design criteria – Also did not need touch screen for competition Design Changes: Acceleration Pedal Previous Design • Design Criteria – Ergonomic to fit driver – Highly reliable • Alterations in Design – Design Simplified to Current Design increase reliability – More ergonomic for driver Design: Safety • Design Criteria – Must have a 5-point or 6-point harness – Driver Must Be Isolated from High-voltage – Front Impact attenuator – Side impact structure – Must have at least 3 Large Emergency Shut Off buttons • How we meet/exceed criteria – We have a 5-point harness that corresponds to Formula SAE regulations – High-voltage wires are isolated in Side Pods and conduit outside of Side Pods – Impact attenuator fits FSAE regulations – Our Side Impact structure Approved Structural Equivalency – Two Emergency Shut off buttons on either side of roll hoop and one on driver’s dash board, also one main switch – Hairball Controller Interface allows user to limit power Design: Safety Main Switch Safety Harness Emergency Stop Switches Hairball – Controller Safety Suit & Helmet Interface Design: Impact Attenuator • HRH-10/OX – 3/16 – 4.0 HexWeb Honeycomb • 7 – 1” layers separated by steel sheet • 650psi Typical Stabilized Strength • Designed to absorb K.E. of 945lb, 15mph car & driver at less than 20G’s (capable of stopping greater mass than required by Formula Hybrid) Design Changes: Body • Body covers from front tip back to the main roll bar • Side Pods fully enclosed • Molded body to fit over front shocks and allow room for the impact attenuator • Floor and side panels around the motor to protect the motor from debris • Recommendations – Start Early – More than one committed person involved Performance Testing • Testing has been done for several different aspects of the car – Acceleration – Autocross – Endurance • Testing still needs to be completed for – Braking • Testing is also serving the purpose of acquainting the drivers with the handling of the car Performance Tests: Acceleration & Braking • Tests were preformed to see if the car can reach the design specifications set with the higher weight • These tests allow the drivers to learn the sensitivities of each of Completed Testing Results • Max Speed of 67 mph the pedal systems • Test completed within 0.1 mile Performance Tests: Autocross • This testing is used to demonstrate that the car can fulfill the turning radius requirements that have been set • Autocross testing is also used so that the drivers Completed Testing Results know how the steering • Slalom runs completed to test the suspension and steering will handle • Resulted in sheered grade 2 bolts, all bolts replaced with grade 8 bolts Performance Tests: Endurance • The endurance testing serves the purpose of finding out how long the batteries will last under constant draw • This section of the testing will also allow the team to find out how long it will take to charge the batteries Completed Testing Results • Time lasted : 20 minutes at 10 mph during the halfway point of • Resolution: larger controller and more the endurance race at batteries competition Testing: Conclusions • The testing that has been performed on the car has shown that we meet the design specifications for – Turning Radius – Maximum power available between 20 and 40 mph • We do not meet the requirements for – Lightweight (under 650lbs with driver) • We expect to meet, but have not yet tested – Acceleration from 0 to 60 mph in under 5 seconds (4.5seconds – calculated) – Top speed of 80 mph (85mph - calculated) – 15 minute battery life (at constant speed of 35mph) Project Management: Primary functions • Budgeting • Funding/Sponsors • Scheduling • Managing a Team • Assigning Tasks Budget: Budget $13,265 Drive System Vehicle Dynamics Chassis and Body DC Motor $1,600 Chromoly Tubing $86 Chromoly Tubing $740 Controller $2,860 Spherical Bearings $460 Fiberglass $80 Lead Acid Batteries $1,440 Brakes $160 Shielding $180 Potentiometer $76 Tires $680 Nomex $80 Differential $700 Miscellaneous $250 Battery Management PLC and Touch Screen Driver Interface PC Boards $150 PLC and Modules $286 Safety Harness $180 00 Guage Wire $80 Touch Screen $810 Driver Accessories $430 Master Switch $155 Speed Sensor $55 Miscellaneous $200 Contactor $240 Fuses $66 Miscellaneous $300 Resources: Resources Sponsors: Programs: Personnel: •USA •Pro/Engineer Wildfire 3.0 •Dr. Larochelle – Team Advisor •Grassroots EV •ANSYS •Dr. Grossman – Team Advisor •US Didactic •ADAMS •Larry Buist – Electrical Support •Charles Whalen •OrCAD •Bill Bailey – Shop Supervisor/Welder (FLEAA) •EZ Touch – EZ Panel •John Amero – Machinist •Bob Steele Chevy Enhanced •Bill Battin – Technical Support •FLEAA •EZ PLC Editor •Stephanie Hopper – Lab Director •CV Restoration •LabView •Frank Leslie – Public Relations/EV •C2 Design •PIC Basic Advisor • Brevard Rentals Recommendations: • Scheduling Design completion Give ample time for testing • Managing a Team • Set goals high • Keep the team going but give some time to relax • Assigning Tasks • Don’t overload one person to a task • Assign tasks to the appropriate person Lessons Learned • Interdisciplinary cooperation - Start early with incorporation of electrical systems - Stay in communication - Introduce each other systems to the other group • Leave enough time for testing and troubleshooting • Keep drawings updated as soon as something changes Lessons Learned Examples Recycling of components -Rims -Cost saving -Shocks -time savings -Steering pinion gear -Analysis -Seat -Production -Wheel Brakes -Implementation Recommendations: Suspension: • Anti-roll bars • Data Logging • Keep the car fully electric • Run true performance tests • Keep electrical engineers on the team Future Improvements • To Do: – Build Battery Management System – Check and Adjust Differential Mounting – Improve Real World Motor Performance – Locate Li-Ion/Li-Polymer Sponsor – Evaluate BMS (Battery Management Systems) options Future Improvements For Future REV Form • Schedule testing time on a real track • Reintroduce Lithium Ion batteries as power source • Reincorporate PLC control system • Expand on sensors - Temp, speed - efficiency • Increase Data collection for evaluation of performance Future Improvements For Future Formula Hybrid -Use IC as power generator -Use electric engine for propulsion -Reconsider Capacitors for rapid charging and discharging cycles -Redesign frame to fit all components Questions?!?
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