1
DESIGN AND FABRICATE A FULLY CAPABLE
OFF-ROADER
By
SAYANTAN DAS
Name of the Student Roll No.
SAYANTAN DAS 11ME013
Internship I/ Internship -II Course
At
BAJA STUDENT INDIA -2015
DEPARTMENT OF MECHANICAL ENGINEERING
SESSION 2011-2015.
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A REPORT
ON
DESIGN, SIMULATION AND FAB RICATION OF A FULLY CAPABLE
SINGLE SEATER OFF-ROAD VEHICLE WITH
AUTOMATIC TRANSMISSION
By
SAYANTAN DAS
Name of Student Roll No. Discipline
SAYANTAN DAS 11ME013 4th year B-tech (M.E.)
PROJECT REPORT SUMMITED IN FULFILLMENT OF
THE REQUIREMENTS OF THE COURSE
INTERNSHIP -I ; INTERNSHIP -II
At
BAJA STUDENT INDIA -2015
Guides / Professional Expert(s) Prof R. K. Deb; Prof Vibhuti Jha; Prof K. Srinath
Faculty/ Associate Faculty(s) Prof B.B. Malhotra; Associate Prof Ankur Kashyap
DEPARTMENT OF MECHANICAL ENGINEERING
SESSION 2011-2015.
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CERTIFICATE
This is to certify that the project report titled DESIGN AND FABRICATE A FULLY
CAPABLE OFF-ROADER SAYANTAN DAS , 11ME013 in partial fulfilment
of the requirements of courses, ME-483(Internship-I) and ME-484(Internship-II) at BAJA
STUDENT INDIA , as part of the degree of Bachelor of Technology in Mechanical Engineering
-2015 Is a record of bona fide work carried out under my/
our supervision and has not been submitted anywhere else for any other purpose.
Name of Faculty/Associate Faculty:
Prof. R. K. Deb
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ACKNOWLEDGEMENT
This project on DESIGN AND FABRICATE A FULLY CAPABLE OFF-ROADER, is intended
to give a detailed insight of the understanding of Automobile Engineering, and processed required
to fabricate a vehicle. I hope that this treatise will prove useful to readers seeking an understanding
of building an All-Terrain Vehicle.
It gives me an immense pleasure to express my gratitude towards all who have helped me to
experie
rendering the divine favour throughout this endeavour and immense gratitude we recognise the
moral support provided by my parents.
I express my sincere gratitude to the Head of the Department. Prof. B. B. Malhotra for the
opportunities provided for the completion of this project. I would like to thank Prof. R.K Deb and
Prof. Vibhuti Jha for their immense support and guidance throughout the course of the project.
I would also like to express my sincere thanks to our Project Guide Mr. Ankur Kashyap and Prof.
K. Srinath who provided us with essential knowledge required for commencement and completion
of this project. There constant encouragement and valuable suggestions are the key factor behind
this great success.
f the mechanical and automobile
department and all our friends for their valuable suggestions and cooperation that they have
extended to us without any inhibition.
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TABLE OF CONTENTS
1. Cover Page ..1
2. Title Page 2
3. Certificate ..5
4. Acknowledgement 6
5. Abstract .7
6. Introduction 8
7. About our Design .9
8. Goals and Objectives .. ..10
9. Vehicle Design Aspects . ..11
10. Technical Specifications . 12
11. Frame Design . 13
12. Analysis of Front Impact ...14
Analysis of Side Impact ..15
13. Analysis of Roll Over ...16
14. Analysis of Load during Acceleration 17
15. Vehicle Ergonomics ..18
16. Ergonomic Angles .19
16.1. Vehicle Prototype ..20
16.2. Driver Vision while seated ....20
16.3. Reach Envelope .21
17. Suspension System 22
17.1. Design Process 25
17.2. Anti-Squat and Anti-Dive 26
17.3. Bump Steer 27
17.4. Motion Ratio 27
17.5. Shock Ride Height 28
17.6. Sprung & Un-sprung Weight 28
17.7. Corner Weights 28
17.8. Spring Angle & Spring Rate 29
6
17.9. Wheel Rate . 29
17.10. . 30
18. Steering System .31
18.1. Steering Kinematics ..31
18.2. . ...32
18.3. .... ..33
18.4. .. ...34
18.5. Knuckle Load . .34
19. .35
19.1. .....35
19.2. . .35
19.3. ...37
20. 41
20.1. .
21. Project Plan ....47
22.
23. ...
24.
25.
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INTRODUCTION
BAJA Student India is a college level engineering design competition, held every year at the NIT
Jamshedpur campus. Participating teams comprise of undergraduate & post graduate engineering
students and as a team they are tasked to design, build, test, race, and promote a single-seater 4
wheeler all-terrain vehicle.
BAJA Student India follows the BAJA SAE International rules and procedure. All the delegates
and judges are internationally acclaimed faculties and engineers from the best Colleges and
Automobile Industries.
This event is meant 'FOR THE STUDENTS' and main focus is on the educational aspect of the
competition. Department of industries, Government of Jharkhand, being the principle sponsors and
Tata Being the title sponsors for this there will be a great amount of exposure between the technical
groups and automobile industrialists.
BAJA student India started in 2013 at NIT Jamshedpur, organised by the Federation of Motor
Sports Council India, Members of NIT Jamshedpur and Baja aluminous and technical inspectors
Roulle, President of OptimumG, and Judge for Formula SAE series, USA. Mr. James. Pat Clarke,
Semi-retired Consultant, Sydney, NSW. And Mr. Stephen.M.Fox, President/Director of
engineering powertrain technology, USA.
This year Baja Student India has 44 Teams participating in the final event from all over India and
is expecting a footfall of more than 50,000. Teams include the best from India who have been
participating in Indian and International Motorsports Events.
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ABSTRACT
Team Saksham
new vehicle which can endure the off-track designed by Delta Inc, organizers of Baja Student
India-2015, held at NIT, Jamshedpur. This vehicle will be used to compete in this competition
and hence it is designed in accordance with 2015 SAE Mini-Baja Rules and Regulations.
The design process of the vehicle is iterative and is based on various engineering and reverse
engineering processes depending upon the availability, cost and other such factors. So the design
process focuses on:
Safety, Serviceability, Cost, Standardization, Strength and ruggedness, Driving feel and
ergonomics, Aesthetics
The design criterion followed here is design for the worst and optimize the design while avoiding
over designing, which would help in reducing the cost.
9
OUR DESIGN
The design process of the vehicle is iterative and is based on various engineering and reverse
engineering processes depending upon the availability, cost and other such factors.
So the design process focuses on:
Safety, Serviceability, Cost, Standardization, Strength and ruggedness, Driving feel and
Ergonomics, Aesthetics.
The design criterion followed here is design for the worst and optimize the design while avoiding
over designing, which would help in reducing the cost. We proceeded by setting up the budget
for the project. Throughout the design process we distributed the budget in such a way that
if we assign more money to one system, we reduce that amount from some other system.
Our last year vehicle design was based on the criterion of prevention of failure, as that year no
one knew the track and the obstructions prevalent over there. So the procedure of over designing
was followed as the safety of the driver is of utmost importance.
The main aim this year was to decrease the overall weight with keeping in mind the overall
durability of the vehicle and increase the overall performance.
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GOALS AND OBJECTIVES
1. To fabricate a fully operational vehicle in a time period of 5 months, the vehicle was designed
in accordance to the SAE International Baja -2015 rule book. The time period will divided,
33% for designing, 33% for fabrication and 33% for testing.
2. Reinstall a mechanical drivetrain with a CVT and chain reduction and tune the CVT to
maximize performance.
3. Design and install a new front suspension that has better travel and is lighter, and still just as
strong as the current design.
4. To design and install a trailing arm suspension system in the rear.
5. Design and install a new steering system that properly balances the effects of caster and camber
to improve the handling of the vehicle in an off road environment. Maintain the original design
requirements set for the vehicle: steering wheel rotation limited to 180 degrees in each direction
with maximum steering angle of 30 degrees.
6.
capable of locking ALL FOUR wheels, both in a static condition as well as from speed on
pavement and .
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VEHICLE DESIGN ASPECTS
1. Vehicle must be capable of carrying one person 75 in. tall, weighing 250 lbs.
2. Vehicle must be safe for a 95th percentile male operator.
3. Width of the vehicle must not exceed 162 in.
4. The vehicle must be capable of safe operation over rough land terrain including, but not
limited to, obstructions such as rocks, sand jumps, logs, steep inclines, mud and snow and ice.
5. No components of the vehicle must come loose during a rollover.
6. All wiring must be sealed, protected and securely attached.
7. Vehicle must contain front and rear hitch point along the longitudinal centerline.
8. There must be a firewall between the cockpit and the engine and fuel tank compartment. It
must cover the area between the lower and upper lateral cross members on the Rear Roll Hoop.
9. The vehicle must have a hydraulic braking system that acts on all wheels and is operated by a
single foot pedal. The pedal must directly actuate the master cylinder through a rigid link.
10. The brake system must be capable of locking all four wheels, both in a static condition as well
as from speed on paved and unpaved surfaces.
11. Vehicle must be capable of completing a four hour endurance test.
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TECHNICAL SPECIFICATION
S.
No
Vehicle
Specifications
Old Vehicle New Vehicle
1 Wheel Base
2 Wheel Track
3 Overall
Length
4 Ground
Clearance
5 Kerb Weight 294 Kg 220 Kg
6 Brake Type All four disc
brakes with
Tandem
cylinder.
All four disc brakes with Tandem
cylinder.
7 Stopping
Distance
9 m 6.97 m
8 Max Power 10 HP @ 3600
rpm
10 HP @ 3600 rpm
9 Max Torque 19.6Nm @
2800 rpm
19.6 Nm @ 2800 rpm
10 Transmission
Type
Mahindra Alfa
4 Speed
Continuously Variable Transmission
(CVTech)
11 Front
Suspension
SLA Double
Wishbone
SLA unparalleled Double Wishbone
12 Rear
Suspension
SLA Double
Wishbone
Trailing Arm
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FRAME DESIGN
The Chassis is the component in charge of supporting all other vehicle subsystems and taking
care of the driver safety at all times.
The Chassis design need to be prepared for impacts created in any certain crash or roll over. It
must be strong and durable, taking in account the weight distribution for better performance.
This year our team used AISI 1020 Steel tubes with outside diameter of 28.3 mm and thickness
of 2mm. AISI 1020 was used because it has the required carbon percentage, i.e. 0.18-0.24%, and
substantial amount of bending strength.
Finite Elements analysis
In order to prove the safety of our chassis design we decided to use Catia and Solidworks, due to
its low memory requirement and ease of use.
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Analysis was done for the following impacts:
1. Front impact:
Load Applied: 23240 N; Max Stress: 2.49*108 N/m2 ;
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2. Side Impact:
Load Applied: 15303 N; Max Stress: 2.32*108 N/m2 ;
M
16
3. Roll Over:
Load Applied: 15303 N; Max Stress: 2.32*108 N/m2 ;
17
4. Load during Acceleration:
Acceleration Applied: 9.8m/s2 ; Max Stress: 5.47*106 N/m2 ;
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VEHICLE ERGONOMICS
The ergonomics of a cockpit of any vehicle is a crucial part. It the vehicle controls are not
strategically placed, the operator will not be able to reach to the peak performance.
In extreme cases, the safety of the operator and other could be jeopardy, if controls are not readily
available at all times.
For our vehicle we had created a prototype and had collected data from different drivers and found
out the optimal angles that have to be set to attain the most comfortable and safe ride for a
prolonged period of time and in extreme conditions.
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Final Design Values for the Cockpit:
Ergonomic Angles:
S.No Parameters Std Range Design Value
1 Angle at
Elbows
120-140o 122.921o
2 Angle at Knee 120-150o 120.026o
3 Angle at Back 8-15o 14o
4 Pedal Space N/A 33 litres
5 Min Visibility
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Vehicle Prototype:
Driver Vision while Seated:
21
Reach Envelope:
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SUSPENSION SYSTEM
One of the stated goals of this Major Qualifying Project was to re-design the front suspension and
steering systems in order to improve handling and performance. Each component from the mounting
points out was re-engineered. The mounting points could not be altered without extensive
modification to the frame so the system was designed around this constraint.
In the course of designing an off-road vehicle, much attention must be paid to the terrain it will be
navigating in order to develop a fitting suspension system. A Baja vehicle suspension must provide
the car with the ability to compete in every event including the hill climb, endurance, and
manoeuvrability competitions.
A sufficient suspension will have the necessary practical features such as adequate ground clearance
and suspension travel to allow navigation of the terrain as well as provide comfort and control to
the driver.
The goal of any suspension is to maximize the contact between the tire and the track surface. Two
basic methods of accomplishing this goal include reducing the weight of the suspension, which is
called the un-sprung mass and increasing the stiffness of the mounting points on the vehicle or
sprung mass. Reducing the un-sprung mass will decrease the effects of inertia in the system allowing
it to react more rapidly to bumps.
There are several different types of suspensions, each with their own advantages; however the
double wishbone designs allows for the most control of ride behaviour and isolation of individual
tire movement. For this reason, most performance vehicles employ double wishbone suspensions
on the front axis and this design was no different. In off-road vehicle design, some attributes that
provide necessary ride height and manoeuvrability must be prioritized over other parameters that
might improve handling but cannot be optimized under the necessary design requirements.
After researching and ranking the suspension characteristics discussed above, the team was able to
define both static and dynamic goals for the new design. The design of the front suspension and
steering will be explained as one since the two are closely related and changes made to one system
can greatly affect the other. The suspension is one of the most critical component in a BAJA buggy.
It is vital that the suspension is responsive enough and has sufficient travel to handle a wide variety
of off-road terrain at speeds of 30 to 45 mph.
Overall goal of suspension is to keep the vehicle as stable as possible and provide sound
ergonimical ride over rough and unpredictable terrain and ensure that all exposed undercarriage
members are provided enough elevation to avoid impact with mentioned obstacles.
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Vehicle Level Target:
Total Mass: : 280 Kg
Unsprung Mass : 82 Kg
Sprung Mass : 192Kg
S. No: Parameters Front Rear
1. Ride Height
2. Ride Frequency 1.69 Hz 2.02
3. Jounce
4. Rebound
5. Wheel Rate 17.54 Kg/in 29.066 Kg/in
6. Natural Frequency 1.074 Hz 1.27 Hz
7. Motion Rotio 0.75 0.6
8. Spring Rate 41.34 Kg/in 84.893 Kg/in
Supension Hardpoints:
1. Toe: +1.7 o
2. Camber: -2 o
3. Roll Centre Height(F)
5. SAI 9 o
6. Scrub Radius 28.3mm
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DESIGN PROCESS
First we have to decide which suspension is better for us in according with different benefits of
different suspension. In most of the Baja Buggies we go with the Double Wishbone in the front
suspension. For designing it, we first have to see what should be the length of our arms, in that
length what should be the vertical distance between the two arms.
Think of it as Four-Bar mechanism, 2 arms and 1 roll cage and 1 upright side links. Roll cage side
-
down is enough. Then, we decide equal arms or non-equal arm or parallel arm. By simulating it in
designing software like adams or lotus, we check if we can get proper travel or not.
Shocker is mounted on the lower arm, so it would be good to have longer lower to have maximum
travel. To make it longer, lower arm is kept longer than the upper arm. This has disadvantage that
on travelling, it gains more camber angle, to compensate it, initially some negative camber is given.
While iterating we much consider how much roll centre, scrub radius, caster angle, king pin axis
angle we want, all the parameters were kept in mind.
Few Topics are explained:
Anti -Squat and Anti Dive:
Squat is the backward tipping of vehicle. As car accelerates weight is transferred to the back of
the car whose magnitude is the product of mass, acceleration and the ratio of Cg distance from
front wheel and total wheel base. Whereas, dive is the forward tipping of vehicle while braking.
Here weight is transferred from back to front wheel whose magnitude is the product of mass,
acceleration and the ratio of Cg distance from rear wheel and total wheel base. This result into very
rough riding so we use Anti dive and Anti squat geometry.
If we consider front side as double wishbone and rear side as trailing arm, the IC for front side is
intersection of two arm lines as shown in fig. and the line joining IC and centre of wheel gives you
the anti-dive percentage .4L and .6L is the breaking ratio. Line drawn perpendicularly through that
point is major responsible for percentage of anti-dive. If any dive line passes through the top of
- impossible to
give 100% anti-dive because of other geometries like steering, roll. We kept it 50%.
25
Anti-Squat & Anti Dive Design
Bump Steer:
Bump steer is the toe in-toe out of vehicle when it encounters bump. When vehicle comes in
contact with any bump it causes tie rod to move in or out which results into steering effect. To
avoid this there should not be any movement of tie rod during bumps. Keeping these things in mind
we have to place tie rod in such a way that when wheel rotates about IC, the tie rod should also
rotate without any radial movement i.e. tie rod should lie on the line joining the IC and outer tie
rod joint. In other words inner tie rod end must lie on the line connecting the tie rod outer ball
joint with the instantaneous centre of suspension system. For double wishbone parallel arms tie
rod should also be parallel to arm.
http://bajatutor.org/wp-content/uploads/2014/03/an-ti-dive-squat-Naming.jpg26
Calculating Different Parameters of Suspension:
Motion Ratio:
Motion ratio is the ratio of spring travel and wheel travel or it is also the ratio of distance of wheel
and distance of spring from pivot point. It is some time called Installation ratio.
Motion Ratio = (a / b) * sine (Spring Angle)
a = distance from lower arm axis to spring mount.
b = distance from lower arm axis to ball joint.
According to Herb Adams in Chassis Engineering equation is
MR = (a/b)2 * (c/d)2
c = distance from IC to ball joint.
d = distance from IC to wheel centre.
Shock Ride Height:
Sprung Weight = Corner Weight Un-sprung Weight.
Sprung Weight:
It is the height of travel left after sprung mass is applied. A shocker gives 4-5 inch travel when
sprung mass is applied as 40 to 50 percent of shocker gets compressed. So shock ride height is 40
to 50 percent of travel of shocker. It is the weight of the vehicle that is supported by the spring and
is the only weight used when calculating spring rates.
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Un-Sprung Weight:
Un-sprung weight is the vehicle weight that is not supported by the springs. It includes Tire-wheel
assembly, brake rotors and callipers (or drums and components), wheel bearings; steering knuckle,
differential and axle weight, hanging weight of the control arm (or trailing arms on rear axles), 1/2
of the spring and shock absorber weights.
Corner Weights:
It is the weight measured by the contact patches present at the four wheels. By adjusting the corner
weight we can adjust understeer and over steer tendency of vehicle. Increase the ride height at a
corner will increase the weight at that corner and its diagonally opposite corner. And similarly
decreasing the ride height at the corner will decrease the weight at that corner and its diagonally
opposite corner. The other two corner will gain weights. Change in stagger, tire pressures and
springs will change the ride height.
Corner Weight = Total Weight /4
Spring Angle:
It is the angle made by spring to the control arm, it is between 75 and 90 degree.
Spring Rate:
Spring Rate = Static Load / Shock Ride Height.
Static Load = Sprung Weight / Motion Ratio
k = d*G / (8ND3)
k: The spring rate.
d: The wire diameter.
G: T Shear Modulus.
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N: The number of wraps.
D: The diameter of the coil.
Wheel Rate:
Wheel Rate = Spring Rate * (Motion Ratio ^ 2) * spring
Angle Correction:
Spring Angle Correction Factor:
ACF = {cos (Spring Angle) * Spring Rate}
Spring parameters in market Yamaha-Spring parameters
http://www.racingsprings.com/Yamaha/sku/145http://bajatutor.org/wp-content/uploads/2014/04/Wheel-Rate-Lrg.gif29
Suspension Parts Analysis:
Front Control Arm:
Force Applied: 3952N F.O.S: 2.58
Rear Trailing Arm with Upright Assembly:
Force Applied: 4100N F.O.S: 1.6
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STEERING SYSTEM
Steering Kinematics:
Steering was designed with an aim of providing minimum turning radius, minimum slippage,
maximum rolling, and optimum steering ratio, which provides an ergonomically sound steering
system.Steering system is based on Ackerman principle and uses centrally located Rack and Pinion
steering gear box which is typically used in dune buggies.
1. Wheel Track
2. Wheel Base
3. Ackerman Angle 21.28o
4. Inner Lock Angle 44.8o
5. Outer Lock Angle 29.236o
6. Turning Radius 3.25m
7. Steering Ratio 5.08:1
8. Ackerman Percentage 92.5%
9. Steering Arm Length
10. Castor Angle +6o
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system, so learning from last
been provided.
32
Front Wheel Assembly:
33
Steering Geometry
34
Steering Hard Points Location:
Front Knuckle Load Analysis:
Load Applied: 3000 N;
Max Von Mises Stress: 5.23*107 N/m2
35
POWER TRAIN
The Primary Goal of the drive train is to maximize the power delivered to the rear wheels for all
practical vehicle speeds. This goalpeciallyimportant when attempting to power a off road buggy
with a small. Single cylinder engine. All components used in drivetrain should be durable enough
to last the endurance race, as light as possible, and they should occupy am acceptable space given
the restrictions derived from the rest of the vehicle sub-systems, namely the rear suspension. The
nimum of
12 inches of ground clearance.
The team wil be using a Cvtech CVT coupled with a four stage reduction FNR Gearbox with a
gear reducton of 13.55:1.
Engine:
All vehicles competing in the Society of Automotive SAE) Mini Baja Competition must
use the same engine: the Briggs and Stratton OHV Intek model 20. This single cylinder, four cycle,
air-cooled, 52 pound engine is rated for 10 HP at 3800 rpm. SAE uses this engine to level the playing
field between teams. To be competitive, the car needs to be designed to maximize the output
available from this engine. The power curve for this engine, provided by Briggs and Stratton, is
shown below in Figure 1
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Targets:
1. Maximum Velocity 58kmph
2. Uniform Acceleration 2.63 m/s2
3. Maximum Gradability 35o
4. Power to Weight Ratio 45.45HP/tonne
5. Maximum Torque Required 1604.1 N
6. Maximum Torque Available 1902.92 N
Assumptions for drive train Calculations:
1. Tyre diametre
2. Wheel Resistance 107.45 N
4. Gross Weight 280Kg
5. Max Power 10 HP
6. Reduction 13.55:1
7. CVT Hiighest Ratio 3.1:1
8. CVT Lowest Ratio 0.43:1
9. CVT Efficiency 84%
37
Power Train Exploded View
GEARBOX CALCULATIONS :
Engine power @ 3600 rpm = 7.38 KW
Engine Power
Torque
P =
60,000
= 7.46KW
38
Assumptions:
weight=280kg
erb weight=220kg
aximum power = 7.38kW (10 HP)
.
efficiency of the Van Doore type CVT
CVT ratio = 3 - 2.5 ( 800) for 800
39
Table 1: This table displays our numerical data as it relates to our assumptions and the equations
Engine rpm Torque
output (N-m)
CVT ratio Total ratio Torque on
wheel(N-m)
Speed (km/h)
1800 17.88 2.107 27.391 489.75 6.93
2000 18.49 1.929 25.077 463.67 8.42
2200 19.11 1.750 22.750 434.75 10.21
2400 19.30 1.571 20.042 394.16 12.64
2600 19.50 1.393 18.109 353.12 15.16
2800 19.60 1.214 15.782 309.32 18.73
3000 19.57 1.036 13.468 263.56 23.52
3200 19.44 0.857 11.141 216.58 30.33
3400 19.17 0.679 8.827 169.21 40.67
3600 18.63 0.500 6.5 121.10 58.48
Force Required = Wheel Resistance (Fw) + Air Resistance (Fa) + Gradient
Resistance (Fg) + Acceleration Resistance (Fac)
Wheel resistance = Rolling resistance + Road resistance + Slip resistance
40
Neglecting slip resistance:-
Then rolling resistance = fr * mv * g * inclination angle.
fr = coefficient of rolling resistance = 0.045
mv = mass of the vehicle = 280 Kg
Rolling resistance = 0.045 * 280 * 9.81 * cos30 = 107.045 N
Road resistance=0.045*280*9.81=123.606 N
Wheel resistance (Fw) = 107.045+123.606 N
Neglecting, acceleration resistance:-
Air resistance or drag (Fd) = cd* 2*A=247.59 N
2
Gradient resistance (Fg) = mv * g * sin30= 1373.4N
Hence,
Required force = 123.60+107.045 + 1373.4 = 1604.046N
A total force of 1604.046 N is required to push the vehicle at inclination =30
41
BRAKING SYSTEM
The objective to bring the vehicle to rest when desired, under the condition that all four wheels
should lock simultaneously as the brake pedal is pressed.
Key points for implementing Disc brakes in both front & rear is based on the following points:
Heat Dissipation
Low Weight
Centrifugal Cleaning Action
Maximum Deceleration
Parameters Old New
Type Disc ( Front & Rear) Disc (Front & Rear)
Outer Diameter of disc
Brake Type Front-Rear Split Front-Rear Split
Brake Biasing 60(f): 40(r) 50:50
Stopping Distance 9 m at 45 Km/h 6.78 m at 45 Km/h
Leverage Ratio 4:1 7:1
Pedal Force 386 N 350 N
Deceleration 9.8 m/s2 or 1 g 11.51 m/s2 or 1.17 g
42
Braking Mounts On the front Wheel Assembly
Brake
Components
Old New
Calliper Used Driver front right and rear
left: Apache 160
Driver front left and rear
right: Suzuki GS 150
Driver front right and rear left:
Apache 160
Driver front left and rear right:
Suzuki GS 150
Master Cylinder
Used
TVS Girling Tandem
Master Cylinder
TVS Girling Tandem Master
Cylinder
Disc Used
Imported disc for ATV. Front:
43
Braking Calculations:
Assumptions & Requisition:
TVS Girning Tandem Master Cylinder
Brake Type: Front- Rear Split
Leverage Ratio: 7:1
Pedal force: 350 N
Front Wheel & Tire:
Rear Wheel & Tire:
Tire Pressure: 7psi
Coefficient of Friction ( pad wrt disc) = 0.3
Coefficient of Friction ( tire wrt road)= 0.7
Gross Weight = 280 Kg
Taking Moment about Pivot Point,
=> Force on Master Cylinder * 1 = Force on Pedal (350 N) * 7
=> Force on Master Cylinder = 2450 N
Pressure Delivered on Master Cylinder:
= Force on Master Cylinder/ Bore Area of Master Cylinder
= 2450/ 0.031415
= 77988.23 N/m2
Front: Rear Biasing= 60:50
Pressure on Front Line = 46792.938 N/m2
Pressure on Rear Line = 31195.292 N/m2
44
Force Applied by Calliper Piston:
FFront = Pressure on front line * bore area of calliper
= 46792.938 * 0.0491
= 2297.533 N
Similarly,
FRear = Pressure on front line * bore area of calliper
= 31195.292 * 0.0491
= 1531.688 N
Force applied on disc by the calliper:
FfrontDisc = 2 * Force applied by calliper piston * (disc wrt pad)
= 2 * 2297.533 * 0.3
= 1378.519 N
Similarly,
FRearDisc = 2 * Force applied by calliper piston * (disc wrt pad)
= 2 * 1531.688 * 0.3
= 919.01 N
Torque on each Disc:
TFront = Force applied on front disc by calliper * Radius of front disc
= 1378.519 * 0.1651
= 227.59 N-m
TRear = applied on front disc by calliper * Radius of front disc
= 919.01 * 0.1524
= 140.057 N-m
45
Force per Wheel:
FWFront = Torque on Front Wheel/ Radius of the Wheel
= 227.59/ 0.558
= 407.86 N
FWRear = Torque on Rear Wheel/ Radius of the Wheel
= 140.057/ 0.558
= 250.99 N
Normal Force = (tyre wrt ground) * Gross weight of Vehicle
N= 0.7 * 280 * g
= 1920.8 N
Deceleration= Force/ Mass of Vehicle:
Dx= [2( FFrontWheel + FRearWheel) + Normal Force] / Mass of Vehicle
= [2(407.86 + 250.99) + 1920.8] / 280
= [2(658.85) + 1920.8] / 280
= [1317.7 + 1920.8] / 280
= 3238.5 / 280
= 11.56 m/s2 or 1.18g
Stopping Distance:
SD= v2 / (2 * Dx)
= 12.52 / (2* 11.56)
SD = 6.75m
46
Mass Transfer:
Wt = (*h*W* Dx) / b
=>Wt= (0.7*0.457*280*11.56)/1.500
=>W t= 690.30 N
Weight of Vehicle:
W= 280*9.8
=>W=2744 N
Percentage Mass Transfer= 25.15 %
47
PROJECT PLAN
48
D.F.M.E.A
Components Failure
Mode
Causes Failure
Effect
Actions Taken S O D RPN
Brakes Leakage,
Master
Cylinder
Failure
Lose hoses,
punctured
brake lines
Loss of
braking
force and
control
Using separate
Master cylinder
for Front &
Rear brakes,
and use of
genuine parts
5 2 4 40
Wishbone The arm
breaks or
bends
from the
ball joint
or
bushing
Sudden
impact,
stresses in
case of
collision
Damage to
the entire
wheel
assembly,
loss of
control
Analysis done
with high factor
of safety.
6 1 6 36
CVT Belt Belt
stretches,
burns,
slips.
Incorrect
distance b/w
pulleys,
misalignment
of shafts, no
proper vents
for heat
dissipation
Power
cannot be
transmitted
to the
wheels
5 2 2 20
Tie Rod Breaking
of Tie rod
from
joints
Due to
excessive
cornering
forces and
excessive
bump
stresses.
Loss of
control
6 3 1 18
49
Final Design:
Front View:
50
Top View:
51
Side View:
52
Isometric View:
53
Weld Destructive Test:
Welding Process:
54
Front Uprights Machining:
Front Wheel Assembly:
55
Testing Phase:
56