Sae-Fsae-Suspension-And-Frame-Design

971584

Introduction to Formula SAE®
Suspension and Frame Design
Edmund F. Gaffney III and Anthony R. Salinas
University of Missouri - Rolla

ABSTRACT

Formula SAE®.

This paper is an introduction to Formula SAE® (FSAE)
suspension and frame design based on the experience of the
design team at UM-Rolla. The basic theories and
methodologies for designing these systems are presented sothat new teams will have a baseline for their first FSAE
design. Examples will be given based on UM-Rolla’s 1996
FSAE entry.

This paper covers some of the basic concepts of
suspension and frame design and also highlights the approach
UM-Rolla used when designing its 1996 suspension and
frame. The suspension section addresses the basic design
parameters and presents specific examples.The frame
section discusses how to achieve a compromise with the
FSAE design constraints. Finally, the design section gives a
brief overview of the design methodology used by UM-Rolla
for the 1996 race car.

INTRODUCTION
Formula SAE® is a student competition, sponsored by
the Society of Automotive Engineers (SAE), in which
students design, build, and compete with a small formula
style racecar. The basis of the competition is that a fictitious
company has contracted a group of engineers to build a small
formula car. Since the car is intended for the weekend
autocross racer, the company has set a maximum cost of
$8,500. The competition rules limits the race car engine to a
maximum displacement of 610cc with a single inlet restrictor.
Other rules require that the car must havea suspension
system with a minimum wheel travel of 50mm and a
wheelbase greater than 1524mm. The car must also satisfy
safety requirements such as side impact protection [1].

The 1996 team finished 12th in the engineering design
event, while the overall finish was 19th out of 77 competing
teams.
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SUSPENSION GEOMETRY

The suspension geometry section concentrates on some
of the basicareas of suspension design and highlights what
the UM-Rolla design team selected for its 1996 race car
suspension geometry.
FSAE suspensions operate in a narrow realm of vehicle
dynamics mainly due to the limited cornering speeds which
are governed by the racetrack size. Therefore, FSAE
suspension design should focus on the constraints of the
competition. For example, vehicle track widthand wheelbase
are factors governing the success of the car’s handling
characteristics. These two dimensions not only influence
weight transfer, but they also affect the turning radius.

The competition is separated into static and dynamic
events. The static events include the cost analysis, sales
presentation, and engineering design. The dynamic portions
of the competition are the 15.25 mdiameter skid-pad, 91.44
m acceleration event, 0.8 km autocross, 44 km endurance
race, and fuel economy.

Not only does the geometry have to be considered for
FSAE suspension, but the components must also be
reasonably priced for the cost analysis and marketable for the
sales presentation. For example, inboard suspension could be
a more marketable design, while outboard suspension mightcost less and be easier to manufacture.

The FSAE competition was established to provide an
educational experience for college students that is analogous
to the type of projects they will face in the work force. To
participate in FSAE, student groups work with a project from
the abstract design phase until it is completed. Aspects of
engineering design, team work, project management, andfinance have been incorporated into the basic rules of

UM-Rolla chose to use a four wheel independent
suspension system with push rod actuated inboard coil-over
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shocks. This decision was mainly due to packaging
constraints. Furthermore, the appearance of inboard
suspension was considered important for both the design
judging and the sales presentation because of its similarity to...