CAR NO.

#36
FINAL DESIGN REPORT
TEAM ZENITH , G.B.PANT ENGINEERING COLLEGE
BY :
Vardaan Bhatia
(Powertrain, Asst.Design & Marketing Head)
Amal George
(Team Captain & Design Head)



ABSTRACT

The design report focuses on explaining
engineering and design procedure involved
for developing our BAJA vehicle . It sheds
light on the fundamentals used ,material
used and its alternatives.
This report is aimed to explain the readers
the basic mechanics and engineering
techniques used to understand our vehicle
which is made with accordance to all the
rules laid out by BAJA SAE India
Committee 2014.

INTRODUCTION

BAJA-2014 is a event organized by Society
of Automotive Engineers India. The teams
are given the challenging task to design and
fabricate a single seat, off-road, rugged,
recreational and fun to drive, vehicle which
will intended for sale to weekend off road
enthusiasts. The goal of Team Zenith which
is first time parcipant and all its members
participating first time in any SAE
organized competetion vehicle with the most
standardized and commonly used parts to
eliminate the error to the maximum extent
and should comply with all the SAE BAJA
requirements. To achieve our goal the has
been divided into various groups and each
group is assigned a specific component of
the vehicle (Chassis, Suspension, Wheel
Assembly, Steering and Brakes, Power


transmission). For designing, analysis and
optimization of the vehiclecomponents
Various software like SolidWorks(design
and analysis), CATIA (design and analysis),
ANSYS (analysis and simulation). Our team
is divided in following departments-

ROLL CAGE & CHASSIS
POWERTRAIN & WHEELS
SUSPENSION
BRAKING & ECM
STEERING

In this version of the BAJA-India
competition, it is decided to merge with the
international format of the event, to
accomplish this many rules have been
changed and altered and we have complied
with them accordingly.


ROLL-CAGE & CHASSIS


METHOD

The roll cage has been designed by frame
department of our team keeping it Safe,
Light, Strong and Spacious enough for
better driver ergonomics. The kind of body
we are required to manufacture is unitized
body. The rollcage is of utmost importance
for us as it would be the one which would
provide safety tothe driver, mounting points
for various systems andeven ergonomics and
looks to the vehicle.It should be strong
enough to bear the laden load andshould be
designed against impact load that it
mightencounter. The failure criterion for the
roll cage isyielding. Our design of the roll
cage started with ergonomic anddriver
comfort study. We also studied the rules and
safety instructions as per Baja SAE INDIA
2009 rulebook. This was followed by study
of compatibility of various other systems
with the roll cage, as these systems were
developed in the process. Based on these,
we designed a layout which was modified
again and again to take the present shape as
shown in fig r1. Adjacent to fig r1 we also
have the roll cage of last year vehicle as fig
r2. The software used by us is Pro-E and
Solidworksfor 3-D modeling and design

MATERIAL


The material of the roll cage is chosen to
minimise the weight, maximise the impact
strength, bending strength, low price and an
ease of availability of the dimension and
pipe.
We selected AISI 1030 grade carbon steel
tubing withouter diameter of 1 inches(2.54
cm) and a wall thickness of 3 mm as per the
calculations done according to the formula
given in the rule book for the bending
strength of the tube.






MATERIAL Yield
Strength
(Pascal)
Bending
Strength
(Pascal)
AISI 1018 370000000 227.0868803
AISI 1020 350000000 214.8119138
ASTM A106 275790000 241.2061046
AISI 1030 440000000 270.049263


MAJOR DIMENSIONS

Height of Roll Cage 51 inches
Height of RRH 50 inches
Width of RRH 33 inches
Length of Roll Cage 88 inches
Track Width 50 inches
Wheel Base 68 inches

FEA (FINITE ELIMENT ANALYSIS)
The Finite Element Analysis done in
ANSYS software with front impact test, rear
impact test and the roll over test over a
chassis at 24000 N of force.
THE SAFETY FACTORE IS FOUND
TO BE 3.2





BRAKING

An excellent braking system is the most
important safety feature of any land vehicle.

OBJECTIVES
The goals for the braking system were:
1. Good reliability
2. Good performance.

DESIGN APPROACH
The two main types of braking systems
under consideration were Drum and Disc
brakes. But in case of drum braking there is
a high possibility of mud and debris to
gather in the space between the shoe and the
drum. Hence hydraulic brakes are found to
be suitable for all type of terrain across
worldwide. As per the rule book the brake
system must be capable of locking ALL
FOUR wheels in a static condition and
dynamically on pavement AND an unpaved
surface. The vehicle must have atleast two
(2) independent hydraulic braking systems
that act on all wheels and is operated by a
single foot. The pedal must directly actuate
the master cylinder.
Keeping this in mind we will be using two
master cylinders in diagonal split type
fashion. The master cylinders will be
mounted in parallel such that both the
master cylinders are connected to a same
linkage which connects them to brake pedals
and actuates braking in all the four wheels
when foot pedal is pressed.
We will be using discs and callipers of
Maruti 800 which is optimum as per our
need. And also will help us easily mount the
disc and the calliper on Maruti 800 modified
knuckle.
We will be using steel tubing for brake
lines with 3/16 O.D
We have calculated the dynamic weight
using the formulae as
given below:
Front axle dynamic load
= w1 + ( g) W (H L)
Rear axle dynamic load
= w2 ( g) W (H L)



Front View
Parameter Value
Front and Rear Disc O.D 215 mm
Caliper Bore Dia 50 mm
Master Cylinder Bore Dia 19.05 mm
Brake Fluid DOT-4
Vehicle Weight Distribution Front to
Rear
45:55







Where,
W1=Weight on the front axle in the static
condition.
W2=Weight on the rear axle in the static
condition.
g = Acceleration due to gravity.
W= Total weight of the vehicle.
H=Height of center of the gravity.
L= Length of the wheel base.
Deceleration of the vehicle is .
POWERTRAIN

The engine provided to us is the
Briggs&Stratton Race 305CC Engine
with 10 HP power and 19 Nm Torque rating
.The model is equipped with specialized
OHV intake for maximum performance.

OBJECTIVE :
Use most cost efficient and standardized
drivetrain .
Design an efficient gear coupling for
minimum losses.

TRANSMISSION SELECTION :
Keeping in mind the above objective
commonly used Mahindra Alfa Gearbox
with 4 forward and 1 reverse gear sequential
manual gearbox was selected. Many other
alternatives and recent technological
advances like Automated Manual or Semi-
Automatic Transmission were rejected
keeping in mind the cost factor and reducing
the probability of failures .

Keeping in mind the recent changes in
racetrack with more steep obstacles ,
increased angle of Hill Climb event and
introduction of Suspension event ,it was
decided that Torque was more important
factor than Maximum Speed at disposal .
For this , it was chosen to use the gearbox in
reverse orientation, thus reversing the gear
ratios .

NORMAL ORIENTATION


Final
Gear
Ratios

Speed
(Km/hr)

Tires
D=25
First
Gear

31.45:1

0.65D

16.25
Second
Gear

18.70:1

1.109D

27.70
Third
Gear

11.40:1

1.82D

45.5
Fourth
Gear

7.35:1

2.82D

70.5
Reverse
Gear

55.08:1

0.38D

9.5

REVERSE ORIENTATION


Final
Gear
Ratios

Speed
(Km/hr)

Tires
D=25
First
Gear

55.08:1

0.38D

9.5
Second
Gear

32.75:1

0.63D

15.75
Third
Gear

19.96:1

1.04D

26
Fourth
Gear

12.87:1

1.61D

40.25
Reverse
Gear

31.45:1

0.65D

16.25

Maximum Speed with 25 tires at
300RPM is 40 Km/Hr
Velocity on road = 2 NR60
(1000G) Km/hr
Where,
G=gear ratio
N=revolutions per minute
R=outer radius of the tire in meters.
Apart from this, for mounting the engine we
are going to use neoprene rubber mountings.

Top View





Side View






STEERING

Objectives:
Provide directional stability
Facilitate straight ahead recovery after
completing a turn
Reduce steering report
Minimise tire wear

Mechanism: Rack and Pinion
Rack and Pinion Steering Mechanism was
chosen considering simple design and easy
mounting.

Geometry: Ackermann
With Ackermann Geometry, all 4 wheels
pivot about the same point, ensuring that the
vehicle doesnt slip during sudden turns.

Steering Specifications - Front
Castor +5 degree
Camber -1.5 degree
KPI +8 degree
Toe Out +1 degree
Scrub Radius 65 mm
Lock Angle(outer) 40 degree
Lock Angle(inner) 29 degree
Steering Ratio 16.5:1
Turning Radius 3.556 metres
Wheelbase 68 inches
Wheeltrack 50 inches
No of turns to achieve wheel lock to
lock=3.25

Steering Specifications Rear
Caster +5 degree
KPI +8 degree
Camber 0 degree
Scrub Radius 57 mm
Toe 0 degree

Steering Knuckle
We are using the Maruti 800 Type-II
Knuckle for both front and rear wheel
assemblies. The knuckle has been modified
from McPherson type in order to
accommodate the A-arms. The final design
has been made in order to accommodate the
required specifications.










Modified knuckle images, analysis and
assembly






SUSPENSION

We are using double wishbone suspension in
the front and rear
with unequal, non-parallel
A-arms because it has the following advantages:
Independent suspension ideal for the rough
terrain
More wheel travel dissipates energy
from road shocks and gives smoother ride
Better load distribution than McPherson Strut
Control Camber Gain in roll and eliminate
Bump steer
Desirable roll centre heights, achieved nose
type
dive axis
A-Arms Design and Material
AISI 1030 tube with OD 1 and 3mm wall
thickness for a-arms and chassis pivots
AISI 1020 tube with OD 2 and wall thickness
5mm for the ball joint sleeve
Hyundai i20 ball joints

Front A-Arms


Front Roll Center Height is 224 mm
Rear A-Arms Rear Roll Center Height is 411 mr.

Upper A-Arm

Modified knuckle
Shock
absorber
Upper and Lower A-arms
Ball joint sleeve


Total No. of turns 11
Spring Stiffness 21.5
N/mm
No. of Active turns 9
Total Length
(Spring +Damper)
370mm
Spring Length 260 mm
Safe Travel of Spring 112.5 mm
Shock Absorbers

The preliminary design considerations
were :
Estimated vehicle weight without
driver-285kgs
Weight of driver and accessories-
90kgs
Total weight 375 kgs
Unsprung mass-100kgs
Sprung mass-275kgs
Weight distribution : 60-40 (rear-
front)
Springs Specification-Front

Spring Wire Diameter, d 10 mm
Mean Coil Diameter, D 80 mm
Springs Specification-Rear

Spring Wire Diameter, d 10 mm
Mean Coil Diameter, D 70 mm
Safe Travel of Spring 84.1 mm
Maximum Travel of
Spring
100 mm
Spring Stiffness 32.1
N/mm
No. of Active turn s 9
Total No. of turns 11
Spring Length 230 mm
Total Length
(Spring + Damper)
490mm

Initial compression after driver is seated is 25.7


TIRES

Selecting the tires is one of the most
important things as the whole vehicle is in
contact with the road on these 4 points or
rather patches. Also for designing an all
terrain vehicle tires form the most important
part. They should be such that they are able
to provide enough traction on all kind of
surfaces so as to transmit the torque
available at the wheels without causing
slipping.

FRONT
Outer diameter of tire 25 inch
Outer diameter of rim 12 inch
Tread width 8 inch
Aspect ratio - 1
Number of plies 4

REAR
Outer diameter of tire 25 inch
Outer diameter of rim 12 inch
Tread width 10 inch
Aspect ratio - 1
Number of plies 4

ADVANTAGES:
1. Built with a 4 ply rating and a reinforced
casing makes these one of the most puncture
resistant tires in the market today.
2. Large shoulder knobs wrap down the
sidewall to provide excellent side to pull out
of the ruts without causing sidewall failure.
3. The deep tread and open wing design
provides excellent clean-out with each lug
and an improved traction.
4. Special natural compound delivers added
traction.
5. Smaller tires in front results in a smaller
magnitude of moment on the wishbones due
to cornering forces during steering.
6. Use of the larger outer diameter tire at the
rear helps to provide good ground clearance
and also 10 inch treads provides good
traction to the power wheels.

REFERENCES

1. S.S.Rattan ,2005,Theory of Machines
2. V.B. Bhandari ,2007,Design of Machine
Elements
3. SAE , 2008 ,Advanced Vehicle
Technology
4. Thomas D. Gillespie ,2008
,Fundamentals Of Vehicle Dynamics

5. Shigley, J.; Mischke C. ; Budynas, R.
(2003) Mechanical Engineering Design.
Seventh edition. McGraw Hill.

6. Race Car Vehicle Dynamics by Millikens
&
Millikens

7. Automobile Engineering by Dr. Kirpal
Singh

ACKNOWLEDGEMENT

The design process is not a single handed
effort and so it is my team, whom I wanted
to thank for standing with me under all
circumstances. I would also like to express
my gratitude towards our Mechanical
department and on the whole towards the
college for supporting us and believing in
us. SAE has provided us with an excellent
platform for learning and showcasing real
life projects.
We specially like to mention our faculty Mr.
Deepak Sharma (HOD, Mechanical) and
Prof. O.P. Sharma (Principal ) for all their
help, support and mentoring.

CONTACT

Vardaan Bhatia
(Powertrain, Asst.Design & Marketing
Head)
Vardaan510@gmail.com
09718205404

Amal George
(Team Captain & Design Head)
Amalcar41@gmail.com
9013848288