structural performance analysis of formula sae car - Jurnal Mekanikal

Jurnal Mekanikal, December 2010
and knowledge, whole of the car was re-modeled and re-fabricated for international
participation in USA as per the SAE rules. This time reduction of chassis weight
minimally by 10% using new materials and efficient design was decided as one of the
main objective of car development. New materials were deemed to use to widen the
structure’s strength and re-modeled the design to inculcate more driver comfort, safety,
structure triangulation and reduced inertial properties etc. The work started from the
review of technical reports of several winning universities. Their main points regarding
materials, design and load estimations were noted and discussed. Along with it,
orthographic drawings, finite element analysis (FEA) reports of existing car’s chassis
were also brainstormed and reasons of high stresses and displacements were tried to
discover. Modes of load distribution and their deformation concepts were taken care of
from various reference books. Some of the concepts are also enunciated in this paper to
help other universities while preparing the design of their car.
2.0 CHASSIS LOADING
Frame is defined as a fabricated structural assembly that supports all functional vehicle
systems. This assembly may be a single welded structure, multiple welded structures or a
combination of composite and welded structures [1]. Depending upon application of loads
and their direction, chassis is deformed in respective manner briefed as follows [2]:
i. Longitudinal Torsion
ii. Vertical Bending
iii. Lateral Bending
iv. Horizontal Lozenging
2.1) Longitudinal Torsion
Figure 1: Longitudinal Torsion [3]
Application of equal and opposite forces act at a certain distance from an axis tends to
rotate the body about the same axis. Automobiles also experience torsion while moving
on road subjected to forces of different magnitudes acting on one or two oppositely
opposed corners of the cars as shown in Figure 1. The frame can be thought as a torsion
spring connecting the two ends where suspension loads act [2]. Torsional loading and
resultant momentary elastic or permanent plastic deformation and subsequent unwanted
deflections of suspension springs can affect the handling as well as performance of car.
The resistance to torsional deformation is called as stiffness and it is expressed in
Nm/degree in SI units. Torsional rigidity is a foremost and primary determinant of frame
performance of cars.
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