shell eco marathon chassis and body - u-cursos · chassis shell steering ... 2008/2009 supermileage...
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Design Team 16 Peter Inglis Scott Flindall Jason Belliveau
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Agenda
Background Goals
Requirements
Design Considerations
Chassis
Shell
Steering/Wheels/Brakes
Budget
Next Steps
Question Period
12/4/2009Super mileage Chassis and Body – Design Team 16 2
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Background
Competition Goals
The principle of the Shell Eco-marathon is simple: to design and build a vehicle that uses the least amount of fuel to travel the farthest distance.” - Shell
Improvements from 2008-2009 Car
A 15% reduction in weight from the 2008/2009 Super-mileage car.
Reduce rolling resistance as well as air drag from the 2008/2009 Supermileage car.
Design a chassis and body which will help the Super-Mileage team place 1st in the 2010 Shell Eco-Marathon in Houston, Texas.
12/4/2009Super mileage Chassis and Body – Design Team 16 3
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Design Requirements
Design Requirements
Chassis Structural Integrity, Visibility, Vehicle access
Body Max height < 100 cm & < 1.25 times track width
Width < 130 cm
Length < 350 cm
Ventilation
Steering assembly Track width > 50 cm
Wheelbase >100 cm
Total weight of vehicle < 140 kg (w/o driver)
12/4/2009Super mileage Chassis and Body – Design Team 16 4
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12/4/2009Super mileage Chassis and Body – Design Team 16 5
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Initial Considerations
Observations 2008/2009 Car
Large
Heavy
42.5 lb Body
46.6 lb Chassis
Poor visibility
Chassis Entirely supporting
Lightweight
Small
Good driver position
Safety
Body
Non load bearing body
Wheels inside or out
Construction requirements
Cost
Steering / Wheels / Brakes
Simple, precise
Good brakes from 2008/2009
High performance bearings from 2008/2009
Custom machined hubs / spindles
12/4/2009Super mileage Chassis and Body – Design Team 16 6
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12/4/2009Super mileage Chassis and Body – Design Team 16 7
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Chassis Constraints
Requirements
Fit engine & drive train – (8” x 8” x 10”) envelope
Contain driver – Reasonable driving position
Safely support
a driver(120lbs),
all components(Motor/drive train 50 lbs) and body
Support installation of a safety harness
12/4/2009 8Super mileage Chassis and Body – Design Team 16
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Design Process –Chassis
Material & Budget
Considerations Non Structural Body
= Space Frame
Strong, Lightweight materials.
Chassis
Carbon Fiber vs. Aluminum
12/4/2009Super mileage Chassis and Body – Design Team 16 9
Image courtesy of www.composite-resources.com
Image courtesy of www.smallparts.com
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Carbon Fiber Tubing vs. Aluminum Tubing
Strength Weight
0
100
200
300
400
500
600
700
6061-T6 Aluminum Tube Braided Carbon Fiber Tube
Ksi
0
0.05
0.1
0.15
0.2
0.25
0.3
6061-T6 Aluminum Tube Braided Carbon Fiber Tube
Lb
s/ft
12/4/2009Super mileage Chassis and Body – Design Team 16 10
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Chassis Material Selection
Material Selection Cost
12/4/2009Super mileage Chassis and Body – Design Team 16 11
Carbon Fiber
Very Expensive
Very High Strength to Weight
Aluminum
Inexpensive
Workable
Predictable
Best material for this application
0
10
20
30
40
50
60
70
6061-T6 Aluminum Tube Braided Carbon Fiber Tube
$/f
t
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Stress Analysis of Chassis
Initial calculations
Approximated 2D frame
Modeled as beams under bending and axial loading
Analytically solved Maximum moment location and magnitude
Approximate required tubing
12/4/2009Super mileage Chassis and Body – Design Team 16 12
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Aluminum Tubing Selection Process
In tube stress Weight
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
1.5" 1/16" Wall
1.25" 1/8" wall
1.25" 1/16" wall
1" 1/8" wall
1" 1/16" wall
3/4" 1/16" wall
Str
ess
(Psi
)
0
0.1
0.2
0.3
0.4
0.5
0.6
1.5" 1/16" Wall
1.25" 1/8" wall
1.25" 1/16" wall
1" 1/8" wall
1" 1/16" wall
3/4" 1/16" wall
We
igh
t(lb
s/ft
)
12/4/2009Super mileage Chassis and Body – Design Team 16 13
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FEM Analysis 2D mesh
Triangular elements.
Worst case scenario loading condition Proper constraints
Adjust mesh size Observed convergence
0
2000
4000
6000
8000
10000
12000
14000
16000
00.511.522.5
Str
ess
(p
si)
Mesh Size (in)
Stress VS Mesh Size Convergence
12/4/2009 14Super mileage Chassis and Body – Design Team 16
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Chassis Analysis
- Results display a safety factor above 3.0
- Tool to observe high stress locations, stress concentrations.
12/4/2009 15Super mileage Chassis and Body – Design Team 16
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Chassis Design
Safety
Roll Bar Shell regulations
Safety Harness 5 point safety harness
Last years harness will be mounted in similar fashion
Also provides a lightweight seat for the driver
12/4/2009Super mileage Chassis and Body – Design Team 16 16
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Final Chassis Design
Chassis
1 ¼ ” .065 wall Aluminum Tube
1 ¼” 0.125 wall square tube
1/16 ” sheet aluminum
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12/4/2009Super mileage Chassis and Body – Design Team 16 17
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12/4/2009Super mileage Chassis and Body – Design Team 16 18
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Steering Design
Considerations
Rack and Pinion Pros
Small space required
Cons Relatively expensive and heavy
4-Link Style Pros
Lightweight, simple, inexpensive
Cons Steering operation not intuitive
Ackerman Style Setup Pros
Improves rolling efficiency when turning
Cons Requires more precision to work
correctly More expensive parts
12/4/2009 19Super mileage Chassis and Body – Design Team 16
Image courtesy of Desertkarts.com
Image courtesy of ihvpa.org
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Design Choice
4 Link Style Adjustable
Relatively simple to construct
Lightweight
Total weight: approx. 1.5 lb
Total cost: approx. $50
12/4/2009Super mileage Chassis and Body – Design Team 16 20
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Final Design
Rolling Components Shell Eco-marathon radials 44-406
150 grams each
Low coefficient of rolling resistance 0.0024 (Tested by PAC car)
Lightweight wheels to be built by Nauss Bike shop
Custom(last years) front hubs and axles, high performance bearings
High performance rear hub
Disk brakes Last years set-up
Good quality
Integrated into spindles
12/4/2009Super mileage Chassis and Body – Design Team 16 21
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Rolling Chassis
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12/4/2009Super mileage Chassis and Body – Design Team 16 23
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Design Process
Shell Design
Closed wheel design Steering not exposed
More compact front end
Smooth, streamlined body
Simplicity of construction Time requirements
3 person team Chassis Construction
Body Construction
Steering / Wheels / Brakes components
12/4/2009Super mileage Chassis and Body – Design Team 16 24
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Shell Design
Shape
12/4/2009Super mileage Chassis and Body – Design Team 16 25
Shell conforms to chassis dimensions
Polycarbonate windshields
Will be placed during driver fitting/testing
Collaboration with Team 15 to integrate an air intake and exhaust outlet.
Get access to CFD software
Testing/refinement
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Shell Material Selection
Carbon Fiber vs. Kevlar vs. Fiberglass
Determining factors: Strength requirement
Weight
Very similar cloth weight
Resin requirements differ, fiberglass requires less
Cost
Carbon Fiber - $39/yard
Kevlar - $30-40/yard
Fiberglass – $8-12/yard
12/4/2009Super mileage Chassis and Body – Design Team 16 26
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Shell Material
Fiberglass Composite
Divinycell H 60 3/8“ Rigid Foam
4lbs/ft^3
Workable
Scored grid, flexible.
Fiberglass Boat cloth
6oz /yd^2
MAS Epoxy Kit
~ 10lbs / ¾ Gallon
No mold required!
12/4/2009Super mileage Chassis and Body – Design Team 16 27
Images courtesy of: www.jamestowndistributors.comwww.masepoxies.com
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Final Body Design
Body
6oz Fiberglass cloth
Epoxy and Hardener
3/8 “ Polystyrene Foam core
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Estimated total weight
Approx. 58 Lbs (conservative)
Approx 35% weight reduction
More compact, better driving position
12/4/2009Super mileage Chassis and Body – Design Team 16 28
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12/4/2009Super mileage Chassis and Body – Design Team 16 29
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Final Design
Budget
Overall Low costs
Bang for buck material
Local purchases
Marine Fiberglass Supply
Metals-R-Us
Nauss Bike Shop
Local machining
Reusing components
Component Cost(CAD)
Body
Components
Supports $35
Raw Material
Fiberglass cloth $50
Epoxy/Hardener $250
Foam $300
Polycarbonate windshield $30
Body construction Materials - PPE, Plywood Etc $170
Frame
Raw Material
1 1/4" Aluminum Tubing 1/16 wall 6061 $60
1 1/4" Square tubing 1/8" wall 6061 $8
Aluminum Sheet 1/16" 5052 $30
Gussets/Brackets
C Channel 6061 2w * 1.5D * 1/8" 6061 $10
Wheels
Components
Tires $230
Rims $225
Steering/Brakes
Components
Steering linkage $52
Other
misc
Nuts/Bolts/Washers/Fasteners $100
Grand Total $1,550
12/4/2009Super mileage Chassis and Body – Design Team 16 30
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12/4/2009Super mileage Chassis and Body – Design Team 16 31
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Next Steps
Body Refinement
CFD over the break
Working to access CFD software
Construction Planning
Collaboration with team 15
Drive train Fitting , Air intake, Exhaust, Rear hub, Component Mounting, throttle controls
12/4/2009 32Super mileage Chassis and Body – Design Team 16
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Next Steps -Construction
Schedule
12/4/2009Super mileage Chassis and Body – Design Team 16 33
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Competition
Testing Feb 9 – Mar 1
Car leaving March 1
Competition Houston, Texas
March 26 -28
12/4/2009Super mileage Chassis and Body – Design Team 16 34
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12/4/2009 35Super mileage Chassis and Body – Design Team 16
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Area of potential revision
Steering setup Ackermann Angle Comparison
May need to revise steering geometry
Rack and pinion located
Inexpensive
Lightweight
Throttle and Brake controls
0.64
1.58
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60
Wh
ee
l An
gle
Dif
fere
nce
(D
eg
)
Turning Radius (ft)
2008/2009 Car
2009/2010 Car
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0.64
1.58
0
1
2
3
4
5
6
7
8
9
10
0 5 10 15 20 25 30 35 40 45
Wh
ee
l An
gle
Dif
fere
nce
(D
eg
)
Turning Radius (ft)
2008/2009 Car
2009/2010 Car
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