FLORIDA INSTITUTE OF TECHNOLOGY
COLLEGE OF ENGINEERING
Design Presentation
Project: 2007 R.E.V. Team
Presented By:
Elizabeth Diaz
Kathy Murray
Jason Miner
AJ Nick
Jared Doescher
Dave Wickers
Josh Wales
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
Chassis Redesign
Body Redesign
Mounting Points
Aeros/Ground Effects
Vehicle Dynamics
Suspension System
Steering System
Braking System
Driver Interface & Ergonomics
Cockpit Design
Safety Equipment
Driver Interface
Drive System
Motor
Drivetrain
Control System
Battery System
Cooling System
Shielding System
Electrical
Battery Management
Instrumentation
Data Transfer System
Power Management
Team Organization: REV Design Teams
Team Lead:
Design Teams
Elizabeth Diaz
Drive System Team:
Vehicle Dynamics Team:
Chassis & Body Team:
Josh Wales
AJ Nick
Kathy Murray
Jason Miner
AJ Nick
Dave Wickers
Jason Miner
Dave Wickers
AJ Nick
Jared Doescher
Kathy Murray
Electrical Team:
Matt Reedy
Valerie Bastien
Audrey Moyers
Kristi Harrell
Driver Interface Team:
Oliver Zimmerman
Dave Wickers
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
Max stress: 22126 psi
Cornering
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:
k
Fl

y1  y 2
a tan(
)
2L
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
Static Camber
Table 3.8: Rear Suspension Geometry
-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
Kingpin Offset
5˚
.915"
Caster
Kingpin Offset
3˚
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)
Nomex fabric on walls and bottom for
electrical insulation and fire protection
Odyssey Battery,
Model PC680
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
Fuse
Albright SW200
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
– 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
Current Design
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
increase reliability
– More ergonomic for driver
Current Design
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
Safety Suit & Helmet
Hairball – Controller
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
the pedal systems
Completed Testing Results
• Max Speed of 67 mph
• 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
know how the steering
will handle
Completed Testing Results
• Slalom runs completed to test the
suspension and steering
• 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
during the halfway point of
the endurance race at
competition
Completed Testing Results
• Time lasted : 20 minutes at 10 mph
• Resolution: larger controller and more
batteries
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
(FLEAA)
•OrCAD
•Bill Bailey – Shop Supervisor/Welder
•Bob Steele Chevy
•EZ Touch – EZ Panel
Enhanced
•John Amero – Machinist
•FLEAA
•EZ PLC Editor
•CV Restoration
•LabView
•C2
•PIC Basic
Design
• Brevard Rentals
•Bill Battin – Technical Support
•Stephanie Hopper – Lab Director
•Frank Leslie – Public Relations/EV
Advisor
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
Recycling of components
-Cost saving
-time savings
-Analysis
-Production
-Implementation
Examples
-Rims
-Shocks
-Steering pinion gear
-Seat
-Wheel Brakes
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?!?