Eco-marathon

Shell
TEAM 15
Joyce Atadero
Amanda Doolittle
Brian Nault
Alex Weiss
Eco-marathon
FRAME DESIGN
OBJECTIVE
The Shell Eco-marathon competition challenges students to
design, build, and test an energy efficient gasoline-powered
vehicle for the competition in Detroit, Michigan on April 9
through April 12, 2015. Students go through the design and
build process with a focus on energy efficiency.
FRAME FEA
The riveted aluminum frame was a new design this year. 6061-T6 aluminum tubing was chosen as the frame
material instead of steel for weight savings. The joints were riveted to retain the material strength
compared to a welded design. The frame was the area of greatest focus as it would be the base for the rest
of the vehicle and included many of the main factors considered in safety. The vehicle had no suspension as
comfort was not a priority. ⅛” structural cherry-Q rivets were used for their strength and vibration resistant
qualities.
CLIENT VALUES
1.
2.
3.
4.
5.
Safe
Reliable
Durable
Fuel Efficient
Easy to Control/Operate
6.
7.
8.
9.
Aesthetically Pleasing
Comfortable
Simply Designed
Within Budget
Maximum Stress: 2,129 psi
(6061-T6 Aluminum Tensile Yield Strength: 40,000 psi)
Creo Frame Model
Maximum Displacement: 0.016 in
Frame During Construction
RIVET TESTING
VEHICLE STATS
ENGINE & DRIVETRAIN DESIGN
WEIGHT
Total Vehicle Weight: 154 lbs
Frame: 20 lbs
Steering & Controls: 25 lbs
Engine & CVT: 35 lbs
Body: 20 lbs
Miscellaneous: 54 lbs
DIMENSIONS
Vehicle Length: 9 ft 2 in
Frame Height: 26 in
Frame Width: 21 in
Track Width: 35 in
ENGINE
49cc Honda Metropolitan Scooter
Single Cylinder 4-Stroke
Compression Ratio 10.1:1
DRIVETRAIN
Stock Scooter CVT
Attached Sprocket & Chain
A 49cc 2013 Honda Metropolitan scooter engine was used from the
2014 vehicle. The team disassembled the engine to repair cylinder
and piston damage. The CVT from the scooter was left as-is and a
bicycle chain was run from a sprocket on the output of the CVT to a
sprocket on the 20” bicycle wheel. A bicycle type spring chain
tensioner was also utilized.
Five T-shaped test pieces were created to simulate an unsupported node. Weights were used to test the
tube bending and shear failure of various rivet types, and deformation was recorded using a dial
indicator.
BODY DESIGN
The body is a painted carbon fiber shell. Two layers of 3K 2x2 Twill 199GSM Aero
50 inch carbon fiber were laid over a custom foam mold. The body was sanded
and cut before painting. The benefits of carbon fiber outweighed those of
fiberglass in all regards except cost and was within the budget constraints. The
side and front windows were made from 0.030” and 0.060” polycarbonate
sheets respectively that were riveted to the body. The cockpit door design used
a piano hinge and a cabinet roller latch.
STEERING & CONTROLS DESIGN
The steering system allows for a turning radius well
within the required 8 m radius. The design of the
uprights gave the vehicle Ackermann steering and
adjustable camber. The front and rear brakes were
separately activated with foot pedals. The starter
switch, ignition button, horn button, and throttle
paddle were mounted on the steering wheel.
SCHEDULE
Shell Eco-marathon Competition: April 9-12, 2015
Note: the 1/8” Cherry Q Structural Rivets did not fail during testing at the maximum weight available
BUDGET & SPENDING
FUEL SYSTEM DESIGN
Location: Detroit, MI
The fuel delivery system needed to be redesigned to comply with
competition rules for fuel injected engines. Instead of an electronic
fuel pump which is not allowed, a pressurized air tank and regulator
system was designed to pressurize the fuel bottle at the starting line
to the stock fuel injector pressure of 43 psi.
DRIVING STRATEGY
Note: Testing the engine on the dynamometer was not completed due to time constraints
The strategy to conserve fuel was to accelerate up to approximately
25 mph and then turn-off the engine to coast down to approximately
10 mph, preferably on downward slopes and turns, such that the
overall average speed of the vehicle was 15 mph during the run.
Photo Credit: Bryan Mitchell/AP Images for Shell
Acknowledgements:
Dr. Martin Morris - Client
Dr. Richard Johnson - Advisor
Jon Kellogg
Dave Miller
Gayle Deynzer