Momentum - November 2020 - 13

STUDENT GENERATION

SES testing.

Running a monocoque chassis.
SAE that contains a set of calculations
to aid students in proving structural
equivalency of monocoques to that of a
steel tube frame chassis. The SES
calculates stiffness and strength using
physical test data and simple mechanics
of materials equations to ensure the
safety of the chassis. To minimize
weight, the T31 Monocoque has seven
different laminates. The laminates vary
from five to ten plies of prepreg CFRP
and 0.5" to 0.75" thick Al honeycomb.
The geometry of the car was shrink
wrapped to the powertrain assembly
and the chassis templates to minimize
weight. The chassis templates consist of
two cockpit templates and the driver
template. The cockpit templates
determine the minimum size of the
cockpit opening and the width/height of
the driver's leg area. The driver template
is performed with a 95th percentile male
template in driving position, and the
head of this driver template has to be
below the imaginary line drawn between
the top of the front roll hoop to the rear
roll hoop to ensure rollover safety.
Computational fluid dynamics is also
utilized to validate the aerodynamics of
the chassis to minimize drag and ensure
proper airflow to the rear wing and the
floor. Weight distribution was also
considered during the geometry design.
The target was set using an in-house
competition lap time simulator. Using

MOMENTUM

this, a relationship between vehicle
center of gravity vs. lap time was
determined. To achieve this target CG of
the vehicle, the weight distribution of
the monocoque was moved as forward
as possible by altering the driving
position and roll hoop positions.
Manufacturing a single-piece carbon
fiber reinforced plastic monocoque is an
intensive and expensive process that
spans six months. These steps allow the
part to be a single piece, which
eliminates the use of any lap joints and
which thus saves weight and jig
hardpoints reliably with precision. Using
tooling foam provided by Coastal
Enterprises, the male top half and male
bottom half master models were then
machined by our five-axis machining
sponsor, Janicki Industries. Thanks to

the five-axis machining process, all the
attachment points on the chassis are
jigged by drilling precision holes which
are to hold dowel pins. This method was
able to achieve the positional tolerance
target and has been validated using a
3-D scanner. Afterwards, the master
model was painted with a vinyl ester
primer provided by Composites One,
sealing the open cell foam.
After many hours of sanding, the
master model was ready for the resin
infusion. Using the supplies provided by
AIRTECH, this process yielded a top half
and bottom half female carbon fiber
molds which were then clamped
together. This process allowed the final
part to be manufactured in one piece
and minimized the effect of thermal
expansion during cures. The dowel pins
that were installed in the master model
located drill bushings that were
laminated within the carbon fiber molds.
With the resin infused carbon fiber
molds complete, the final layup took
place. Used were prepreg CFRP provided
by Toray, film adhesive provided by
Heatcon, and Al honeycomb provided by
Ergonomics
sketch.

November 2020 13



Momentum - November 2020

Table of Contents for the Digital Edition of Momentum - November 2020

Momentum - November 2020
Questioning the “if it ain’t broke, don’t fix it” cliche
BENEFITS U
Michigan Baja Racing goes 4WD
A testimony to experiential learning
One-on-One Liam MacGillivray
Talking chassis
BRIEFS
2021 ID.4 is Volkswagen’s first U.S.-market dedicated EV
UX designers and “engineering chefs” cook up unique user interfaces
SAE 101: student engagement
Be an optimist and an opportunist
Dossier: Madeline Corrigan of Northwestern University
Momentum - November 2020 - Momentum - November 2020
Momentum - November 2020 - Cover2
Momentum - November 2020 - 1
Momentum - November 2020 - Questioning the “if it ain’t broke, don’t fix it” cliche
Momentum - November 2020 - BENEFITS U
Momentum - November 2020 - Michigan Baja Racing goes 4WD
Momentum - November 2020 - 5
Momentum - November 2020 - 6
Momentum - November 2020 - A testimony to experiential learning
Momentum - November 2020 - 8
Momentum - November 2020 - 9
Momentum - November 2020 - One-on-One Liam MacGillivray
Momentum - November 2020 - 11
Momentum - November 2020 - Talking chassis
Momentum - November 2020 - 13
Momentum - November 2020 - 14
Momentum - November 2020 - BRIEFS
Momentum - November 2020 - 2021 ID.4 is Volkswagen’s first U.S.-market dedicated EV
Momentum - November 2020 - UX designers and “engineering chefs” cook up unique user interfaces
Momentum - November 2020 - SAE 101: student engagement
Momentum - November 2020 - Be an optimist and an opportunist
Momentum - November 2020 - Dossier: Madeline Corrigan of Northwestern University
Momentum - November 2020 - Cover3
Momentum - November 2020 - Cover4
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