Q. Suggest a material most suited and appropriate to be used in Body works of the vehicle.

Keep in mind the rules related to the Body works in FB rulebook. Select a material based
on economically feasibility and availability.
Ans:- Based on the rule book and after searching a few forums, I found Chromium Molybdenum
Steel (AISI 4130) and Plain carbon steel (AISI 1018) to be suitable as the parameters match
those given in the rulebook AISI 4130 steel is stronger than AISI 1018 this will allow for a
tubing with thinner diameter for construction of chassis and will reduce weight But for
economically feasibility AISI 1018 is cheaper compared to AISI 4130

SUSPENSION
Q1. Explain the parameters associated with wheel alignment. Describe their effects and
suggest the range of values of each parameter with suitable reason.
Ans:- Alignment refers to an adjustment of a vehicle’s suspension – the system that connects a
vehicle to its wheels. It is not an adjustment of the tires or wheels themselves. The key to proper
alignment is adjusting the angles of the tires which affects how they make contact with the road.
Parameters associated with wheel alignment are as follows:-
 Camber
 Caster angle
 Toe
 Roll Centre

1.Camber is the angle of the wheel relative to the vertical of the vehicle, and depending on the
tilt, is either considered positive camber or negative camber. When the top of the tires tilt away
from the center of the vehicle you have positive camber, and when the top of the tires are tilted
inward you have negative camber. One isn't better than the other, but varying camber angles
have different effects on your vehicle.

 Positive Camber - When your wheels are tilted outward, the vehicle has improved
stability.
 Negative Camber - High performance vehicles that require better cornering tend to use
negative camber, because it gives the driver more control in this regard.

For racing purposes we only really see negative camber, i.e. the tops of the tyres are pointing
inwards. There are two advantages to running camber, one being improved stability and two,
more grip at high speed. As the speed of the car increases, the tyres are pressed further
downward as downforce generated by the wings and underfloor rises. When the driver turns into
a corner at speed, the car will lean over to the opposing direction of travel, which consequently
shifts the position of the tyre’s contact patch. Running optimum camber allows for maximum
contact between rubber and track during a corner on the outside tyre, increasing the grip
available and thus the speed at which the car can take the turn.

By having little camber on the rear tyres, grip is consistent for right and left corners despite the
inside front tyre picking up off the ground a little (in extreme cases). Overall stiffness of the
suspension and anti-roll bars also play a part in how camber enhances grip, but that’s more
experimental work than theory. However if the camber angle is too aggressive it can cause
severe tyre wear problems.
Camber Angle : -1.5⁰ in front and -1⁰ in rear

2. Caster is the angle that identifies the forward or backward slope of a line that is drawn
through the upper and lower steering pivot points. It does not affect tire wear, but caster does
have an influence on the directional control of the steering. Caster angle settings allow
manufacturers to balance steering effort, high speed stability, and front end cornering
effectiveness.

 Positive Caster - If the line slopes towards the rear of the vehicle, then you have positive
caster. The down side to positive caster is if the vehicle does not have power steering. In
this case steering effort will be increased. Positive caster is primarily beneficial to the
vehicle as it increases the lean of the tire when the vehicle is cornering, while returning it
to an upright position when driving straight ahead

 Negative Caster - If the line slopes towards the front of the vehicle then the caster is
negative. Negative caster will allow you to steer less around turns, but may cause you to
drift if you are driving straight forward.

Caster Angle: 6⁰ (front) & -6⁰ (rear)

3.Toe:- Toe is a measurement that determines how much the front and/or rear wheels are turned
in or out from a straight-ahead position. The amount of toe, whether it's toe-in or toe-out, is
expressed as the difference between the track widths as they are measured at the leading and
trailing edges of the tires. Toe is expressed in degrees or fractions of an inch, and while your
wheels should be pointed directly ahead as you are traveling straight forward, there are some
benefits to toeing depending on the type of vehicle that you drive.

The purpose of toe is to ensure that all four wheels roll parallel to one another. However, race
cars use toe-out to promote enhanced turning ability. Street cars, or basic passenger cars, use toe-
in because there is no need to corner quickly. Toe-in also provides increased stability because it
discourages turning. If your vehicle has the proper amount of toe you should experience ideal
straight line stability, corner entry, and very little tire wear.

Toe Angle: 0.3⁰ in front and -0.3⁰ in rear.

Ans:- The purpose of the car’s suspension is to keep all fourwheels in optimal contact with the
ground under any and all conditions. A well-designed suspension must handle bumps and uneven
surfaces as well as dynamic cornering, braking, and acceleration. The Formula car is a racecar
purpose built for a prepared track, so performance and handling will be prioritized over
smoothness and suspension travel. It is generally a system of shocks (dampers), springs, uprights
and arms that altogether keep a vehicle suspended above ground on its wheels. The major
component involved in the system includes damper & springs, wishbones, knuckle/upright and
wheels. A Double wishbone Pushrod actuated suspension design was primarily used because of
the aerodynamic and adjustability advantages it gives. They consist of an inboard mounted
spring a push rod and a bell crank assembly. The main requirement here is a structure that will
absorb the energy and transfer it to the frame without disturbing the whole system. The study
ofthe forces at work acting on a moving car is called vehicle dynamics.

Types of suspension system:

1.Non-independent/Rigid suspension has both right and left wheel attached to the same solid
axle. When one wheel hits a bump in the road, its upward movement causes a slight tilt of the
other wheel.

A. Torsion Beam

Also known as the twist beam suspension, the torsion beam suspension system is simple and
manufactured at a low cost. Commonly found at the rear, the system uses trailing arms integrated
with a cross member that twists as the wheels move. If we are to plot it on a chart, it would be in
the middle of a solid axle and an independent suspension, and in most cases, it's classified as a
semi-independent suspension system because of how the beam twists in response to force. The
design allows for a roomier cabin as the suspension system is more compact and simpler. It is
also relatively cheap to produce and rigid at the same time. It is often found on more affordable
and smaller sedans and hatchbacks.

B.Live Axle

A live axle is simply a driven solid axle. Meaning, it transmits power to the rear wheels, unlike
its torsion beam counterpart which has no power being fed to the wheels. Live axle rear
suspensions are commonly found on buses, light trucks, and some light and medium-duty SUVs
and pickups. The system can either be sprung by coil springs or leaf springs. It’s also important
to note that since the system is more rugged, it is more reliable with concern to heavy load
capacities.
2.Independent suspension allows one wheel to move up and down with minimal effect to the
other.

A.Double Wishbone / Double-A Arm Suspension:-

The Double Wishbone suspension also has an independent design, so the turning angle and
suspension movement will not affect the geometry angle, because the angle will remain
constant.

The Double Wishbone suspension has drawbacks due to the fairly large space it requires. On
top of that, when you want to replace a shock breaker or shock absorber, the disassembly
process takes a long time.This suspension is fairly easy to get damaged in its parts, such as
broken ball joint at the bottom or top, long tie rod, and end tier rod. To avoid various damage
to the car, you can do spooring regularly.
B. MacPherson Strut

This type of independent suspension system uses either a wishbone or a substantial compression
link that is stabilized by a secondary link. Some people refer to it as a shock absorber built inside
a coil spring. It is commonly found under front-wheel-drive cars. A MacPherson strut is among
the most cost-effective independent suspension system as it uses fewer parts, meaning it’s
simpler and easier to manufacture.

The MacPherson strut is one of the common types among the independent suspension systems.
Due to its simplicity, it does not take up much space, making it an ideal option for smaller and
more compact vehicles. The simplicity of its structure also means it’s easier to manufacture and
troubleshoot than other kinds of independent suspensions. 
Q3. What is roll-over? As an engineer, how would you reduce roll-over during cornering?
Also discuss the function of sway bar in reducing roll-over.
Ans:- Roll center can be roughly defined as an imaginary point about which a body rolls, due to
high lateral forces.

When applied to vehicles, its a point about which a vehicle body rolls when acted upon by lateral
forces. It may occur during a sharp turn or due to some heavy weight placed on the roof-top.

The position of the roll center decides the stability of a vehicle when acted upon by lateral forces.
It may be above the ground, below the ground or somewhere close to the ground. The suspension
geometry of a body decides the roll center of any vehicle. Roll center height is different for each
vehicle type. It can be altered to improve stability and can be corrected using wheel alignment
procedures.
This is the point the car rolls around during weight transfer from side to side, i.e. when
cornering. This is because all centrifugal forces are directed through the CoG (centre of gravity),
which is directly above the RC, therefore the car’s mass will push away from the direction the
car is travelling in and rotate around the RC point.

The height of the RC will change with both the angle of the wishbones and also camber.
Generally speaking, a higher wishbone angle will create a higher RC. Flatter wishbones will
have the reverse effect.

The front and rear roll centres often differ from eachother, as you can see in the illustration
above. The roll axis is the line between the front and rear roll centres. Note that both the RCs and
CoG are three dimensional coordinates.

The higher the RC is at the front (i.e. moving it towards the CoG), the more responsive the car is
and the less steering input required for a corner. This also reduces the overall roll of the car,
which is important from an aerodynamic perspective – too much roll can disturb how the air
passes over the car during a corner.

On the contrary, the RC is often much lower at the rear of the car. The tell-tale sign of this is that
the top rear wishbone in particular is often angled slightly down towards the floor, and the lower
wishbone at a little-to-no angle at all. Positioning the RC lower at the rear allows for more roll
and squat – the transfer of weight heading towards the back of the car due to accelerative force.
The lower RC will therefore improve traction as the driver picks up the throttle on corner exit.
The idea of a sway bar, which is connected to either both front or both rear wheels (some cars
have one at the front, some have one at the rear and performance vehicles tend to have one at the
front and rear) is that it resists the vehicle’s tendency to roll as it corners, thus helping to keep
weight on the inside wheels as the vehicle corners improving grip and cornering control.

Note that a sway bar only works when one wheel is either higher or lower than the other; it’s aim
is to try and keep things level. And this is great for performance and road cars but it’s not always
ideal for 4x4s which when you’re off-road will want as much wheel travel as possible.
Obviously, the whole point of a sway bar is to try and maintain an even weight distribution from
one side to the other.

A sway bar works by resisting the twisting force applied to it when one wheel moves down or up
compared with the other wheel and weight transfers from one side of the vehicle to the other –
when you’re turning a corner, for instance. And, in that resistance, the bar tries to keep the
wheels as level as possible. The sway bar connects your vehicle’s suspension components (one
side of the vehicle to the other) and is mounted to the suspension control arms. It’s worth noting
that sway bars run through bushings to ensure they don’t move up and down and can only twist.

So, as the vehicle turns a corner and weight moves from one side to the other (in the case of a
right-hand turn the vehicle rolls over to the right. As the wheel begins to move up towards the
body, the sway bar twists which forces the weight to transfer back across to the other side of the
vehicle. The result of this action is that the vehicle begins to level out, thus minimising the roll
action when cornering.