DESIGN, ANALYSIS AND FABRICATION OF SUSPENSION SYSTEM...

International Journal of Scientific Rese

DESIGN, ANALYSIS AND FABRICATION OF SUSPENSION SYSTEM FOR ALL

TERRAIN

R. Sivasubramaniam1, P. Dinesh

2, R. Sathish

1,2 Dept. of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India

3,4,5,6 Dept. of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India

7 Dept of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India

ABSTRACT

Suspension system is a part of the vehicle which absorbs the various forces on

prevents those forces from directly reaching the chassis of the vehicle. It also offers stability to the

vehicle through rough patches of road and undulations as well as comforting the occupants f

jolts and bumps. An All-Terrain Vehi

terrains with ease. The suspension

than what a conventional road going vehicle has to undergo and therefore has to be designed and

made to the highest of standards. A double wishbone suspension or upper and lower A

suspension setup is a versatile type of suspension that allows for easy control and adjustment of

various parameters like castor, camber, toe, scrub radius, roll centre,

damping and rebound are taken care of by air springs to reduce the weight of unsprung masses. The

suspension system has to be designed, tested and

geometry is iterated in multitudinous ways to achieve

Keywords—double wishbone suspension, A

hard points, recessive wheel travel, damping, motion ratio, unsprung mass, geometry an

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I. INTRODUCTION

The suspension is a system of component

that connect the wheels to the chassis of the

vehicle. It allows for the relative motion

between the wheels and body of the vehicle.

A suspension wouldn’t really be necessary if

all the roads in the world were flat without

undulations, but that is as impossible as

International Journal of Scientific Research and Innovations V (2018)8


TERRAIN VEHICLES

, R. Sathish3, M.C. Vignesh

4, P. Vineeth Kumar

5, S. Yuvaraja

Pradeep Kumar7

Dept. of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India

Dept. of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India

Engineering, Dhanalakshmi College of Engineering, Chennai, India

Suspension system is a part of the vehicle which absorbs the various forces on


vehicle through rough patches of road and undulations as well as comforting the occupants f

Terrain Vehicle has the capability to wander through the roughest of

terrains with ease. The suspension of an all-terrain vehicle has to endure forces that are way higher


ade to the highest of standards. A double wishbone suspension or upper and lower A


various parameters like castor, camber, toe, scrub radius, roll centre, pitch, dive, yaw, etc. The


suspension system has to be designed, tested and analysed with dynamic virtual simulations and the

dinous ways to achieve the necessary traits for the al

double wishbone suspension, A-arm, air spring, static parameters, dynamic

hard points, recessive wheel travel, damping, motion ratio, unsprung mass, geometry an

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components

the wheels to the chassis of the

vehicle. It allows for the relative motion

between the wheels and body of the vehicle.

A suspension wouldn’t really be necessary if

all the roads in the world were flat without

undulations, but that is as impossible as it

sounds. All of the undulations and rugged

landscape would lead to a jarring and rough

ride. This gave rise to an automotive

component that needed to soak up the

imperfections that generate enough forces to

damage the various parts of the vehicle

prevent the journey from breaking the

of the occupants. The suspension part has to

deal with the vertical acceleration caused as a

result of the wheels going through those

undulations. This vertical acceleration is

ISSN 2455-7579

arch and Innovations V (2018)8-20


, S. Yuvaraja6, A.R.

Dept. of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India-601301

Dept. of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India-601301

Engineering, Dhanalakshmi College of Engineering, Chennai, India-601301

Suspension system is a part of the vehicle which absorbs the various forces on the vehicle and


vehicle through rough patches of road and undulations as well as comforting the occupants from the

cle has the capability to wander through the roughest of

terrain vehicle has to endure forces that are way higher


ade to the highest of standards. A double wishbone suspension or upper and lower A-arm


pitch, dive, yaw, etc. The


with dynamic virtual simulations and the

the necessary traits for the al- terrain vehicle.

parameters, dynamic simulations,

hard points, recessive wheel travel, damping, motion ratio, unsprung mass, geometry analysis.

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of the undulations and rugged

landscape would lead to a jarring and rough

This gave rise to an automotive

to soak up the

generate enough forces to

damage the various parts of the vehicle and

event the journey from breaking the spines

the occupants. The suspension part has to

ical acceleration caused as a

result of the wheels going through those

undulations. This vertical acceleration is

2455-7579


arrested by springs which absorb the

store it and return it in a damped rebound

motion with the help of a damping setup.

The spring and damper alone does not form

the suspension component. Linkage

mechanisms which connect the wheels and

the spring damper unit, the mounting tabs,

uprights which hold the wheel hubs along

with the spring and damper form the

suspension system of a vehicle. This system

with its entire components function in

harmony to keep the vehicle planted on its

driving path.

The suspension system’s job is not only to

provide a comfortable ride but also to aid in

the road holding and road handling

capabilities of the vehicle. If the wheels were

directly connected to the body of the vehicle,

then the upward accelerating forces would

cause the vehicle’s tires to lose trac

would compromise the driveability of the

vehicle. This could result in a mishap

might even be of fatal nature. Suspension

system prevents the vehicle from losing

traction with the ground to provide

manoeuvrability and tractability.

All terrain vehicles is a vehicle that

through the most roughest of terrain with

good water wading capabilities and off

credentials. The suspension of an ATV must

be well suited to the amplified

befalls. Design of the suspension system is

very much critical to the overall performance

of the ATV. Design of such an effective

system is elucidated in this paper after much

analysis and geometrical iterations.

The design has to be iterated numerous

times through dynamic simulations for the

best solution and achieve a best balance

between the various parameters. Such

parameters are individually assessed and then

compiled together with the vehicles


arrested by springs which absorb the energy,

store it and return it in a damped rebound

motion with the help of a damping setup.

The spring and damper alone does not form

the suspension component. Linkage

mechanisms which connect the wheels and

the spring damper unit, the mounting tabs,

hubs along

with the spring and damper form the

suspension system of a vehicle. This system

with its entire components function in

le planted on its

job is not only to

provide a comfortable ride but also to aid in

the road holding and road handling

capabilities of the vehicle. If the wheels were

directly connected to the body of the vehicle,

then the upward accelerating forces would

cause the vehicle’s tires to lose traction which

would compromise the driveability of the

vehicle. This could result in a mishap that

might even be of fatal nature. Suspension

system prevents the vehicle from losing

with the ground to provide

is a vehicle that can go

terrain with

good water wading capabilities and off-road

credentials. The suspension of an ATV must

be well suited to the amplified force that

. Design of the suspension system is

very much critical to the overall performance

of the ATV. Design of such an effective

in this paper after much

The design has to be iterated numerous

times through dynamic simulations for the

solution and achieve a best balance

between the various parameters. Such

parameters are individually assessed and then

compiled together with the vehicles

specification under consideration

dynamic analysis which visualizes the

compatibility of the chosen values for the

parameters. Individual parameters are altered,

modified or changed to iterate for better

credibility to suit the vehicle’s functions and

endeavours. The changes made for the

parameters also affect the dynamic

capabilities of the vehicle and vice versa.

Minor changes could lead to loss of the other

potential parameters. Hence for each iteration

done, both the static and dynamic parameters

have to be analysed for effective and precise

results.

The desired parameters that dec

effective function of the system are

frequency, height, roll control

pitch, dive and yaw. These parameters are

interlinked with one another and

these is changed, others get

The appropriate setting can be only got by

altering these parameters repeatedly until a

best solution of the titration lot is found with

the least contingencies. Compromise has to

be made in some aspects to achieve the

desired results on some other.

The vehicle’s ride frequency

undamped natural frequency for the give

vehicle and this determines the stiff

softness of the ride. Body roll depends on the

center of gravity of the vehicle and is

generally tackled by configuring the arm

geometry. Ground clearance is an important

criteria for an off road vehicle and higher the

ground clearance, the better

capability. The distance a wheel travels when

it goes through a bump decides the

suppleness of the ride. The motion ratio and

spring stiffness decides the wheel trave

distance. Motion ratio is a factor which

indicates how the suspension is mo

it decides the ratio of forces which get

damped or reach the chassis. Squatting is the

ISSN


nder consideration for the

dynamic analysis which visualizes the

compatibility of the chosen values for the

parameters. Individual parameters are altered,

modified or changed to iterate for better

credibility to suit the vehicle’s functions and

The changes made for the static

parameters also affect the dynamic

capabilities of the vehicle and vice versa.

Minor changes could lead to loss of the other

Hence for each iteration

done, both the static and dynamic parameters

o be analysed for effective and precise

The desired parameters that decide the

effective function of the system arethe ride’s

roll control, wheel travel,

pitch, dive and yaw. These parameters are

interlinked with one another and as one of

these is changed, others get altered as well.

The appropriate setting can be only got by

repeatedly until a

titration lot is found with

the least contingencies. Compromise has to

be made in some aspects to achieve the

ired results on some other.

frequency is the

undamped natural frequency for the given

determines the stiffness or

softness of the ride. Body roll depends on the

center of gravity of the vehicle and is

generally tackled by configuring the arm

Ground clearance is an important

criteria for an off road vehicle and higher the

ground clearance, the better the off road

The distance a wheel travels when

it goes through a bump decides the

suppleness of the ride. The motion ratio and

spring stiffness decides the wheel travel

distance. Motion ratio is a factor which

indicates how the suspension is mounted and

it decides the ratio of forces which get

reach the chassis. Squatting is the

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tendency of the vehicle to lower the rear end

due to the accelerating forces altering the

gravity center towards the rear side which

forces the suspension to compress and lower

the vehicle’s ride height at the rear causing a

squat. Diving is another phenomenon which

is directly opposite to squatting which

during the event of deceleration or braking

Diving forces the front suspension to

compress thus lowering the ride height on the

front which is caused due to the vehicle

shifting its weight forward during braking.

Generally squatting and diving unsettles the

vehicle and has to be kept in check. Anti

squat and anti-dive configurations have to be

considered to avoid excessive diving in the

front or rear. However the best of both worlds

cannot be achieved together for the same

design specification. The most appropriate

design with some trade-offs has to be the goal

for optimum performance.

Recessive wheel travel is another

complication that has to be integrated into the

arm design to compensate the angular forces

on the wheels which introduces a moment on

the arm mounts. To increase the life of the

mounts and to reduce excessive load which

hinders with the movement of the arm on

their pivot points, recessive wheel travel

angle is introduced into the arm and mount

design. Adding this interferes with the design

for anti-diving or anti-squatting and therefore

different possibilities to minimize the

unnecessary properties have to be generated

and tested dynamically. The configuration

which best suits to provide proper recessive

angle along with minimal squat and dive can

be chosen as the ideal setup. Different setups

mayseem tosuit the same vehicle as minor

changes is all that differentiates the designs.

The best choice can be only made by repeated


ndency of the vehicle to lower the rear end

due to the accelerating forces altering the

gravity center towards the rear side which

ompress and lower

the vehicle’s ride height at the rear causing a

squat. Diving is another phenomenon which

ite to squatting which occurs

during the event of deceleration or braking.

Diving forces the front suspension to

ring the ride height on the

front which is caused due to the vehicle

shifting its weight forward during braking.

Generally squatting and diving unsettles the

vehicle and has to be kept in check. Anti-

dive configurations have to be

to avoid excessive diving in the

front or rear. However the best of both worlds

together for the same

design specification. The most appropriate

offs has to be the goal

travel is another

complication that has to be integrated into the

arm design to compensate the angular forces

n the wheels which introduces a moment on

the arm mounts. To increase the life of the

mounts and to reduce excessive load which

movement of the arm on

their pivot points, recessive wheel travel

angle is introduced into the arm and mount

this interferes with the design

squatting and therefore

different possibilities to minimize the

properties have to be generated

configuration

which best suits to provide proper recessive

angle along with minimal squat and dive can

be chosen as the ideal setup. Different setups

e same vehicle as minor

es is all that differentiates the designs.

The best choice can be only made by repeated

tests and making sure the desired aspects of

the vehicle are met to the maximum.

As the suspension system can operate

seamlessly only by integrating all the

individual systems, it is mandatory to know

which alteration would affect

Increasing the recessive wheel travel angle

would increase the vehicle’s dive tendency.

Increasing the ground clearance would

increase the roll of the vehicle

system must be designed in such a way that it

has more advantages than disadvantages as a

system without disadvantage is impossible to

achieve. Also the suspension system

coordinate with the other parts of the vehicle

as well. The CV joint angle would lim

ground clearance of the vehicle. The brake

force generated decides the squat and dive

angle. The front wishbone configuration

influences the steering parameters such as

bump steer, dynamic camber

rod mounting. Therefore inputs from th

steering and drivetrain department are

for designing a system which works well as a

whole vehicle.

The paper proceeds with gathering

information from the various subsystems of

the vehicle, compiling them according to the

specific sections of the design, identifying the

constraints of the design, processing the

design for the front and rear sections, iterati

designs for validity by implying

design within the constraints, dynamic

analysis, self-justification, material selection

and fabrication.

DESIGN CONSTRAINTS

Any suspension design requires prefixing of

standard values or ranges of some parameters

that are necessary to evaluate the variables

involved in the complete design procedure.

The main parameters that are to be fixed

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tests and making sure the desired aspects of

the vehicle are met to the maximum.

As the suspension system can operate

seamlessly only by integrating all the

systems, it is mandatory to know

which alteration would affect which function.

Increasing the recessive wheel travel angle

would increase the vehicle’s dive tendency.

Increasing the ground clearance would

increase the roll of the vehicle. Hence the

be designed in such a way that it

has more advantages than disadvantages as a

system without disadvantage is impossible to

the suspension system has to

coordinate with the other parts of the vehicle

The CV joint angle would limit the

ground clearance of the vehicle. The brake

force generated decides the squat and dive

The front wishbone configuration

influences the steering parameters such as

bump steer, dynamic camber change and tie

inputs from the

steering and drivetrain department are needed

for designing a system which works well as a

The paper proceeds with gathering

information from the various subsystems of

the vehicle, compiling them according to the

design, identifying the

constraints of the design, processing the

design for the front and rear sections, iterating

by implying changes to

design within the constraints, dynamic

justification, material selection

Any suspension design requires prefixing of

standard values or ranges of some parameters

that are necessary to evaluate the variables

involved in the complete design procedure.

The main parameters that are to be fixed

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before entering into the actual design are

explained below.

• The first entity to be fixed would be th

overall dimensions of the all

vehicle. This includes the front and rear

track width as well as the wheel base

.Track width and wheel base range was

fixed to be less than 1600mm and greater

than 1200 mm after a study over existing

ATV dimensions.

• Wheel travel is an important parameter

while designing a suspension system for

ATVs. Considering the terrain conditions

the front wheel travel was fixed as

203.2mm while the rear was fixed as

152.4mm.

• Ride height or Ground clearance is the

distance between the lower most part of

the chassis and the ground. Generally, all

terrain vehicles require large ride heights

in order to overcome the undulations in

the rough terrain. Thus from a terrain

study the GC range was fixed to be

between 280mm to 320mm.

• Natural frequency is defined as the

frequency of vibration or oscillation the

suspension system exhibits as a whole in

the front or rear. For better ride comfort

the value is to be between 0.5 Hz to 2

Hz.

• Weight distribution plays an important

role in designing the suspension system.

The weight distribution is found by first

locating the CG in the wheel base to find

its distance from the front and rear track

when seen in the side view. Then to find

the weight distribution the moment of


tering into the actual design are

The first entity to be fixed would be the

overall dimensions of the all-terrain

vehicle. This includes the front and rear

track width as well as the wheel base

.Track width and wheel base range was

o be less than 1600mm and greater

than 1200 mm after a study over existing

Wheel travel is an important parameter

while designing a suspension system for

ATVs. Considering the terrain conditions

the front wheel travel was fixed as

while the rear was fixed as

Ride height or Ground clearance is the

distance between the lower most part of

the chassis and the ground. Generally, all

terrain vehicles require large ride heights

in order to overcome the undulations in

terrain. Thus from a terrain

study the GC range was fixed to be

Natural frequency is defined as the

frequency of vibration or oscillation the

suspension system exhibits as a whole in

the front or rear. For better ride comfort

value is to be between 0.5 Hz to 2

Weight distribution plays an important

role in designing the suspension system.

The weight distribution is found by first

locating the CG in the wheel base to find

distance from the front and rear track

when seen in the side view. Then to find

the weight distribution the moment of

total weight of the ATV acting on CG is

determined at the front and rear by

considering their respective distances

from CG.

STATIC WHEEL REACTION FORCE

CALCULATION

Free body diagram

Rf =front wheel reaction force

Rr =rear wheel reaction force

• Weight distributed at 60% in front and

40% in rear part.

Sprung Mass, M

Un Sprung MassUn sprung

Total Kerb Weight = 240*9.81 = 2354.4 N

Sprung Weight = 180*9.81 = 1765.8 N.

Unsprung Weight = 60*9.81 =

588.6 N.

[C.G] a = 60% from Wheel base

= 0.60*64 = 38.4 inches [or] 975.36 mm.

[C.G] b = 40% from Wheel base

= 0.40*64 = 25.6 inches [or] 650.24 mm.

By Taking Moment we can find R

follows,

W * [C.G]

2354.4*650.24 = Ra [975.36 + 650.24]

Rf= 941.76 N [For 2 Tyres]

Rf/Tyre = 470.88 N

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total weight of the ATV acting on CG is

determined at the front and rear by

considering their respective distances

REACTION FORCE

Free body diagram

Rf =front wheel reaction force

Rr =rear wheel reaction force

Weight distributed at 60% in front and

Sprung Mass, M Sprung = 180Kg.

Un sprung = 60Kg.

Total Kerb Weight = 240*9.81 = 2354.4 N. Sprung Weight = 180*9.81 = 1765.8 N.

sprung Weight = 60*9.81 =

= 60% from Wheel base

.4 inches [or] 975.36 mm.

= 40% from Wheel base

= 0.40*64 = 25.6 inches [or] 650.24 mm.

By Taking Moment we can find Ra and Rb as

follows,

W * [C.G] a = Rf [C.G b + C.G a]

[975.36 + 650.24]

= 941.76 N [For 2 Tyres]

70.88 N

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W * [C.G] a = Rb [C.G b + C.G

2354.4 * 975.36 = Rr [975.36 + 650.24]

Rr= 1412.64 N [For 2 Tyres]

Rr/Tyre = 706.32 N

FRONT SUSPENSION

DOUBLE WISHBONE SUSPENSION:

The most commonly used suspension

system for ATVs today is the double

wishbone suspension system. This type of

suspension system has two control arms in

the form of chicken wishbone or V shaped

because of which the system is called as

double wishbone suspension .The arms are

also shaped like roman alphabet ‘A’ due to

which these are also referred as ‘A’ arms.

Each arm has three mounting points two on

the vehicle chassis and other is connected to

the knuckle with the help of ball joint. To

obtain the negative camber gain over the

travel short long control arms suspension was

chosen in which the upper arms are shorter

than the lower arms.

DESIGN PARAMETERS

CAMBER

When viewed from the front of the vehicle

the inward or outward tilt of the wheel at the

top iscalled camber. The inward is considered

to be negative while the outward is positive.

A negative camber of 2 to 3 degrees is

preferred for the front due to its ability to produce reaction force to counter the turning side force

which results in better handling.

STEERING AXIS INCLINATION

The steering axis inclination is the angle

made by the line joining the upper and lower

mounts of arms on the knuckle with the tyre

centre axis when seen from the


+ C.G a]

[975.36 + 650.24]

= 1412.64 N [For 2 Tyres]

The most commonly used suspension

system for ATVs today is the double

wishbone suspension system. This type of

suspension system has two control arms in

the form of chicken wishbone or V shaped

which the system is called as

spension .The arms are

also shaped like roman alphabet ‘A’ due to

which these are also referred as ‘A’ arms.

Each arm has three mounting points two on

the vehicle chassis and other is connected to

the knuckle with the help of ball joint. To

tive camber gain over the

travel short long control arms suspension was

chosen in which the upper arms are shorter

When viewed from the front of the vehicle

the inward or outward tilt of the wheel at the

. The inward is considered

to be negative while the outward is positive.

A negative camber of 2 to 3 degrees is

preferred for the front due to its ability to produce reaction force to counter the turning side force

The steering axis inclination is the angle

made by the line joining the upper and lower

mounts of arms on the knuckle with the tyre

axis when seen from the front. An

angle below 15 degrees is considered as any

greater angle would complicate the

suspension geometry.

CASTER

When viewed from the side of the vehicle

the forward or backward tilt of the steering

axis is defined as caster. The forward tilt is

considered to be negative while the backward

is positive. Generally, Positive caster below 5

degrees is taken to obtain self

steering wheel after encountering a turn.

Greater positive caster is produces greater

steering effort.

TOE The inward or outward tilt of the tyres when

seen from the top view is defines as toe. The

inward tilt is Toe in while the outward tilt is

Toe out. For real wheel driven vehicles a

static toe in of 1 to 2 degrees is kept in front

wheels to balance the toe out caused during

acceleration of the vehicle, while the rear

wheels do not require Toe.

INSTANTANEOUS CENTRE

The imaginary point about which the

suspension system tends to

instant centre. The location of front view

instant centre determines the roll

centreposition, camberchange, track change

and steer characteristics. Then

instant centre determines the squat, dive, pitch

and caster change rate. The

gain is obtained by iterating the

instant centrelocation. The track width change

is determined by the height of the instant

centre. Toreduce the track change the instant

centre is kept near to the ground but if the case

the roll centre point lies below the ground

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angle below 15 degrees is considered as any

eater angle would complicate the

When viewed from the side of the vehicle

the forward or backward tilt of the steering

axis is defined as caster. The forward tilt is

considered to be negative while the backward

Generally, Positive caster below 5

degrees is taken to obtain self-returnability of

steering wheel after encountering a turn.

Greater positive caster is produces greater

The inward or outward tilt of the tyres when

iew is defines as toe. The

inward tilt is Toe in while the outward tilt is

Toe out. For real wheel driven vehicles a

static toe in of 1 to 2 degrees is kept in front

wheels to balance the toe out caused during

acceleration of the vehicle, while the rear

INSTANTANEOUS CENTRE

The imaginary point about which the

suspension system tends to pivot is called

location of front view

determines the roll

centreposition, camberchange, track change

characteristics. Then the side view

the squat, dive, pitch

The desired camber

gain is obtained by iterating the hard point and

track width change

height of the instant

track change the instant

is kept near to the ground but if the case

point lies below the ground

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which is unfair .so proper compromise has to

be made between instant and roll centre

ROLL CENTRE.

Whena vehicle negotiates a turn at a high

speed the lateral force acting on the vehicle

would be high which tends to roll the vehicle

about an imaginary point called as roll centre.

The position of roll centre determines roll

characteristics and vehicle handling

Generally roll centre is kept closer to the cg so

that the roll would be minimum.

important aspect for off road vehicle is to

attain the oversteergeometry. This

achieved by placing the front roll centre

than the rear roll centre.

SPRING RATE

Spring rate describes how much the spring

will compress for the given load or weight

placed on it. Generally it is measured pounds

per inch. Greater the spring rate stiffer the

spring which means to compress the s

one inch requires greater load and the case is

inverse in softer set up. For off road vehicles

the proper comprise has to done between roll

centre and spring rate in order to get better

handling during cornering without excessive

roll.

Spring stiffness = Load / Deflection

Ks = S / δ

= 1765.6 / (5*25.4)

Ks = 13.9039 N/mm

MOTION RATIO.

In a suspension system motion

defined as the amount of shock displaced for a

given amount of wheel travel. The

of motion ratio decides the mounting point of


which is unfair .so proper compromise has to

centre point.

a turn at a high

speed the lateral force acting on the vehicle

would be high which tends to roll the vehicle

nary point called as roll centre.

determines roll

nd vehicle handling capability.

is kept closer to the cg so

that the roll would be minimum. The most

important aspect for off road vehicle is to

This can be

centre lesser

rate describes how much the spring

will compress for the given load or weight

it is measured pounds

the spring rate stiffer the

spring which means to compress the spring

greater load and the case is

off road vehicles

the proper comprise has to done between roll

and spring rate in order to get better

handling during cornering without excessive

ess = Load / Deflection

motion ratio is

defined as the amount of shock displaced for a

calculation

of motion ratio decides the mounting point of

shock absorber. The angle at which the shock

is mounted also influence suspension setup

(softer or stiffer).mounting

angle of 0 degree to the vertical then wheel

travel will be equal to the shock

angle increases shock travel decreases or the

suspension becomes stiffer. Higher

stiffer the suspension becomes. The

ratio can be determined by using the formula

Motion Ratio=shock travel / wheel travel.

Maximum Spring Travel = 5 inches.

Wheel Travel = 13 inches

= 5 / 13 = 0.3846

(1)

MOTION RATIO = d1 / d2------------

Substitute eqn.1 in eqn.2, we get

0.3846 = d1 / d2------------------

From CATIA iterations the distance, d2 is about

445 mm.

d2 = 445 mm

Substituting d2 value in eqn.3, we get

0.3846*445 = d1

d1 = 171.147 mm

Then taking moment of above figure

we get following relation,

S cosθ * d1 = Ra * d2

1765.8cosθ * 171.147 = 470.88 * 445

θ = 46.1032

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angle at which the shock

is mounted also influence suspension setup

(softer or stiffer).mounting the shock at an

angle of 0 degree to the vertical then wheel

l to the shock travel. As the

angle increases shock travel decreases or the

stiffer. Higher the angle

becomes. The motion

ratio can be determined by using the formula

=shock travel / wheel travel.

imum Spring Travel = 5 inches.

Wheel Travel = 13 inches

= 5 / 13 = 0.3846 ----------

------------(2)

Substitute eqn.1 in eqn.2, we get

------------------(3)

distance, d2 is about

Substituting d2 value in eqn.3, we get

Then taking moment of above figure about frame axis

* d2

* 171.147 = 470.88 * 445

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NATURAL FREQUENCY

When the car hits a bump the force is

applied to the wheel and the wheel moves

upward. Then the force is transferred to spring

which compress and stores the potential

energy. This potential energy is then released

causing the wheel to rebound. The

of the suspension system after damped(with

spring and shock absorber) by shock is t

as suspension frequency. If the system remains

undamped (with spring and without shock

absorber) then the system would vibrate at its

natural frequency. For the softer suspension

stiffness the frequency would be low and in

case of stiffer setup the frequency would

high. However the common frequency for the

vehicles are 0.5-1.5Hz for passenger cars,1.5

Hz for moderate down force race cars and 3.0

to 5 Hz for high downforce formula one

As for the off road vehicle is concerned the

perfect balance has to be made between the

spring rate, suspension frequency and roll to

get optimal level performance.

f N = (1/2π)√(k/M)

k=spring stiffness

M=unsprung in kg

f N =0.9047 Hz

RIDE RATE

The effective stiffness for the spring and

tyres stiffness is known as ride rate. It

found using the formula

1 / R.R = (KS + KT) / KSKT

Ks=spring stiffness

Kt=tire stiffness

Assume standard tire stiffness for 22 inch


the car hits a bump the force is

applied to the wheel and the wheel moves

the force is transferred to spring

which compress and stores the potential

potential energy is then released

rebound. The frequency

of the suspension system after damped(with

spring and shock absorber) by shock is termed

the system remains

undamped (with spring and without shock

the system would vibrate at its

the softer suspension

stiffness the frequency would be low and in

requency would be

the common frequency for the

1.5Hz for passenger cars,1.5-2

race cars and 3.0

to 5 Hz for high downforce formula one cars.

for the off road vehicle is concerned the

nce has to be made between the

frequency and roll to

The effective stiffness for the spring and

rate. It can be

Assume standard tire stiffness for 22 inch

KT = 10 KN/ m

= (13.9039 + 10) / (13.9039*10)

R.R FRONT = 5.8167 N / mm

DAMPING FREQUENCY

The suspension is not allowed oscillate at its

natural frequency because its takes more

number oscillations to dissipate the spring

potential energy which is absorbed during

bump. This affects the tire traction which

the key property for an all-terrain

dampen the unwanted oscillation damper is

introduced into the suspension.

frequency is dampened by the damper to get

the balanced frequency. The

remains after damping is called damping

frequency.

f d = f N 2

= ( 0.90472)

f d = 0.8184 Hz

DAMPING COEFFICIENT

The ratio of actual damping coefficient (C)

to the critical damping coefficient (Cs

known as damping factor or damping

using the formula damping coefficient can be

found.

Damping coefficient=C\Cs

Assume damping factor =0.2

0.2=C\126.55

C= 632.7972 Ns/m

DYNAMIC ANALYSIS

The entire suspension system was

dynamically analysed using lotus suspension

analysis software. Initially the hard

ISSN


/ (13.9039*10)

The suspension is not allowed oscillate at its

natural frequency because its takes more

number oscillations to dissipate the spring

potential energy which is absorbed during

the tire traction which is

terrain vehicle. To

dampen the unwanted oscillation damper is

suspension. The natural

frequency is dampened by the damper to get

frequency. The frequency which

after damping is called damping

= 0.8184 Hz

ratio of actual damping coefficient (C)

to the critical damping coefficient (Cs) is

known as damping factor or damping ratio. By

damping coefficient can be

Assume damping factor =0.2

The entire suspension system was

dynamically analysed using lotus suspension

analysis software. Initially the hard points,

2455-7579


shock absorber and tire data are entered. Then

the total setup is analysed and various changes

like camber, caster and track variations were

obtained in graph. Several alterations were

made to the various input functions to change

the dynamic motion of the system. The

required setup with the expected way of

motion can be achieved after several minor

changes to the values of the suspension system.

The final graphs got after those changes is

checked for consistency with the design.

Lotus suspension analysis

GRAPHS FOR DYNAMIC VARIATIONS

Camber variation graph


shock absorber and tire data are entered. Then

the total setup is analysed and various changes

like camber, caster and track variations were

Several alterations were

various input functions to change

n of the system. The

required setup with the expected way of

motion can be achieved after several minor

pension system.

got after those changes is

checked for consistency with the design.

GRAPHS FOR DYNAMIC VARIATIONS

Caster variation graph

Toe angle variation

Roll centre variation

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Caster variation graph

Toe angle variation

Roll centre variation

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Half track change

MATERIAL SELECTION

SELECTION OF A-arm MATERIAL

Selection of material is the first step after

designing any component so that it can be

fabricated with desired mechanical properties

Apart from strength and fatigue resistance,

factors such as cost and density should also

be considered and then compromised

according to the requirement. So after a study

of high strength materials with less density

and availability in market at lesser cost with

various ranges of pipe thickness

suitable materials were prepared with their

corresponding properties and other factors to

be considered. These were then compared and

the most suitable one was selected from the

lot.

The selected material was AISI 4130,

which is a type of steel commonly called as

chromoly steel. They exhibit high strength


Selection of material is the first step after

designing any component so that it can be

fabricated with desired mechanical properties.

and fatigue resistance,

factors such as cost and density should also

be considered and then compromised

o after a study

of high strength materials with less density

and availability in market at lesser cost with

ipe thickness,a list of

suitable materials were prepared with their

corresponding properties and other factors to

be considered. These were then compared and

the most suitable one was selected from the

selected material was AISI 4130,

steel commonly called as

ly steel. They exhibit high strength

with relatively lesser density

properties and chemical composition are

tabulated below. SELECTION OF KNUCKLE MATERIAL

Knuckle being the part which conne

arms with the wheel end, transfers all the

forces from the wheels to the arms through

them. So, a material capable of handling

impact loads and torsion loads repeatedly is

considered suitable. Generally, knuckles are

made of solid metal either casted

machined.As they are not hollow

to choose materials with lesser density to

reduce the mass, but there should not be any

compromise in the part’s strength.

Thus Aluminium was chosen due to its less

density and relatively high strength when

compared to other metals. After comparing

various alloys of aluminium with other metals

Aluminium 6061 was chosen which had the

highest strength in aluminium alloys. The

properties of Aluminium 6061 are tabulated

below

CHEMICAL

COMPOSITION

MECHANICAL

PROPERTIES

Element % Properties

Iron 97.22-

98.03

Tensile

Strength

Chromium 0.08-

1.10

Yield strength

Manganese 0.40-

0.60

Modulus of

elasticity

Carbon 0.280-

0.330

Bulk Modulus

Silicon 0.15-

0.30

Shear Modulus

Molybdenu

m

0.15-

0.25

Poisson Ratio

Sulphur 0.040 Reduction of

Area

Machineability

ISSN


with relatively lesser density. The mechanical

properties and chemical composition are

SELECTION OF KNUCKLE MATERIAL

Knuckle being the part which connects the

, transfers all the

forces from the wheels to the arms through

them. So, a material capable of handling

impact loads and torsion loads repeatedly is

considered suitable. Generally, knuckles are

made of solid metal either casted or

machined.As they are not hollow, it is better

lesser density to

, but there should not be any

compromise in the part’s strength.

Thus Aluminium was chosen due to its less

density and relatively high strength when

compared to other metals. After comparing

various alloys of aluminium with other metals

Aluminium 6061 was chosen which had the

highest strength in aluminium alloys. The

operties of Aluminium 6061 are tabulated

MECHANICAL

PROPERTIES

Properties Metric

Tensile

Strength

560Mpa

Yield strength 400Mpa

Modulus of

elasticity

140Gpa

Bulk Modulus 140 Gpa

Shear Modulus 80 Gpa

Poisson Ratio 0.27-0.30

Reduction of 59.6

Machineability 70

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FABRICATION

The fabrication process commences

two prior activities, design for the upright an

arms followed by material justification

through Computer Aided Engineering. T

upright was manufactured initially to

manufacture of the wishbone arms, as the

alignment problems could be av

fixing the position of the knuckles and altering

the wishbone arms to get a symmetric system.

Welding

Tungsten inert gas welding is opted

of the welding operations. TIG welding was

chosen over arc welding for its better control

over the weld that makes it ideal for welding

of critical sections where arc welding would

not come handy. Even smaller cross sections

can be welded with good accuracy. This

CHEMICAL

COMPOSITION

MECHANICAL

PROPERTIES

Component Amount(%) Properties

Aluminium Balance Temperature

Magnesium 0.8-1.2 Ultimate

Tensile

Strength

(MPa)

Silicon 0.4-0.8 Proof Stress

(MPa)

Iron Max 0.7 Brinell

Hardness

(mm)

Copper 0.15-0.40 Elongation

50 mm

dia(%)

Zinc Max 0.25 Yield

Strength

Titanium Max 0.15


The fabrication process commences after

design for the upright and

material justification

r Aided Engineering. The

initially to assist the

anufacture of the wishbone arms, as the

alignment problems could be avoided by

fixing the position of the knuckles and altering

the wishbone arms to get a symmetric system.

t gas welding is opted for all

TIG welding was

chosen over arc welding for its better control

over the weld that makes it ideal for welding

of critical sections where arc welding would

not come handy. Even smaller cross sections

be welded with good accuracy. This

provides for a greater weld strength and high

quality welds that cannot be matched by arc

welding process. The possibility of welding

different materials with good bond strength is

also possible in TIG welding. Different filler

rod diameters are available which increases the

versatility of the process resulting in very good

aesthetics of the weld section.

Mount tabs

The mounting tabs are equally important

parts of the suspension system. They connect

the entire wishbone arms and upper part of the

air spring to the chassis. Hence they must have

good rigidity and strength to be able to

withstand the heavy forces that act on such

minor cross sectioned parts.

Tabs can be designed using

dimensional design software as they don’t

have a complicated design. They are analyzed

for strength and how well they could take up

the stresses. Accordingly the thickness and

material to be used are fixed. The selection of

material also depends upon its weldability

with chromoly steel. Mild steel was a good

choice of material as it could be easily welded

to chromoly steel with good weld strength.

Once the material and dimensions were fixed,

the manufacturing part commenced. Laser

cutting was chosen to fabricate the mounting

tabs as it eliminated the human error that

could occur during manual notching or

drilling. The laser cut mounts were then

welded to the chassis at the specified hard

points that were found during the design of the

hard points.

Knuckle

As said before knuckle is the part which

holds the arms and wheel end together and

MECHANICAL

PROPERTIES

Metri

c

Temperature 260-

310

min

260-

310

MPa

Proof Stress 240-

276

MPa

95-97

mm

Elongation 9-

13 %

276M

Pa

ISSN


ter weld strength and high

quality welds that cannot be matched by arc

The possibility of welding

different materials with good bond strength is

also possible in TIG welding. Different filler

diameters are available which increases the

versatility of the process resulting in very good

are equally important

parts of the suspension system. They connect

the entire wishbone arms and upper part of the

air spring to the chassis. Hence they must have

good rigidity and strength to be able to

withstand the heavy forces that act on such

designed using basic three

dimensional design software as they don’t

have a complicated design. They are analyzed

for strength and how well they could take up

the stresses. Accordingly the thickness and

are fixed. The selection of

material also depends upon its weldability

with chromoly steel. Mild steel was a good

choice of material as it could be easily welded

to chromoly steel with good weld strength.

Once the material and dimensions were fixed,

anufacturing part commenced. Laser

cutting was chosen to fabricate the mounting

tabs as it eliminated the human error that

could occur during manual notching or

lling. The laser cut mounts were then

welded to the chassis at the specified hard

t were found during the design of the

As said before knuckle is the part which

holds the arms and wheel end together and

2455-7579


transfers the load from the tyres to the shocks

.The front knuckle is also known as steering

knuckle as it is designed according to the

steering arm geometry and suspension as well.

The front knuckle is of complex three

dimensional shape as it needs to incorporate

both the steering and suspension hard points as

per their geometry .Due to its complicated

design ,front knuckle is usually casted as

machining becomes expensive with high

material wastage .The front knuckle was an

OEM part bought from the market which met

the requirements of suspension design.

Rear knuckle has a lot simpler design as it

has only the suspension hard points and to

support the drive shaft through bearings in its

hollow center .The rear knuckle was first

designed as per the suspension geometry ie , a

single hard point in its top for arm mount and

two hard points at its bottom for h arm m

The hollow section in center was designed

after selecting the drive shaft and suitable

bearings to support it .The Knuckle being a

solid part , the design was optimized in such a

way that it had lesser volume to reduce its

mass and more than enough strength to hold

mounting points rigid even when acted upon

with heavy impact loads.


transfers the load from the tyres to the shocks

.The front knuckle is also known as steering

designed according to the

steering arm geometry and suspension as well.

The front knuckle is of complex three

dimensional shape as it needs to incorporate

both the steering and suspension hard points as

per their geometry .Due to its complicated

ont knuckle is usually casted as

machining becomes expensive with high

material wastage .The front knuckle was an

OEM part bought from the market which met

the requirements of suspension design.

Rear knuckle has a lot simpler design as it

suspension hard points and to

support the drive shaft through bearings in its

hollow center .The rear knuckle was first

designed as per the suspension geometry ie , a

single hard point in its top for arm mount and

two hard points at its bottom for h arm mounts

The hollow section in center was designed

after selecting the drive shaft and suitable

bearings to support it .The Knuckle being a

solid part , the design was optimized in such a

way that it had lesser volume to reduce its

trength to hold

mounting points rigid even when acted upon

The optimization of Knuckle design was

done by several analysis of them in ANSYS

with minor changes in design and then

comparing the FOS and deformations of each

iteration. The main factors considered

optimization were the shape

machinability. Machinability was a major

factor as the cost for machining increases with

the increase in complexity of the design and

also results in higher machining time. Fin

the design shown below was chosen to be

fabricated.

Wishbones

The wishbones were designed in such a

way that the hard points are connected

together appropriately without allowing any

hindrance to its motion. Also the adjustability

ISSN


The optimization of Knuckle design was

done by several analysis of them in ANSYS

with minor changes in design and then

comparing the FOS and deformations of each

ion. The main factors considered for

optimization were the shape, thickness and

machinability. Machinability was a major

factor as the cost for machining increases with

the increase in complexity of the design and

also results in higher machining time. Finally

the design shown below was chosen to be

wishbones were designed in such a

way that the hard points are connected

together appropriately without allowing any

hindrance to its motion. Also the adjustability

2455-7579


of the wheel end hard points have to be

considered for fine tuning ability. Front part

uses double wishbone setup whereas the rear

part uses an A-arm at the top and an H

the bottom. As justified in the design and

analysis part, the H-arm setup allows for

arresting the toe change at the rear wheels.

The arms are drawn usingdesign software

to present the design visually and computer

aided engineering software is used

the capacity ofthe three dimensional

Changes to the design and pipe cross section

was done and several titrations were

determine the perfect design with ample factor

of safety. Market studies were conducted to

identify the availability of the elected cross

section of the material. Then the analysis was

proceeded with the thickness that was close to

the perceived value. The thickness 1.5mm

having good factor of safety was selected for

the fabrication process and purchased.


of the wheel end hard points have to be

considered for fine tuning ability. Front part

setup whereas the rear

an H-arm at

the bottom. As justified in the design and

arm setup allows for

arresting the toe change at the rear wheels.

arms are drawn usingdesign software

to present the design visually and computer

aided engineering software is used to analyze

the three dimensional design.

cross section

and several titrations were made to

ith ample factor

Market studies were conducted to

identify the availability of the elected cross

section of the material. Then the analysis was

proceeded with the thickness that was close to

The thickness 1.5mm

actor of safety was selected for

the fabrication process and purchased.

The pipes are cut to the specified length and bent

using CNC bending machine to the required angle. For

accommodating a ball joint at the wheel end,

weld bunks are manufactured with

threading which would support the ball joint

and allow for adjustability of the joint. Sleeves

of specified length are cut from the pipe to be

fitted to the arm at the chassis end. Nylon

bushes are used to prevent metal to metal

contact of the sleeve and the fastener.

pipes are then notched at either ends according

to the angles at which the weld bunk and

sleeve are to be placed. The welding of the

sleeves, weld bunks and pipes is t

of the fabrication process. This can be done

either manually or by using fixtures to hold

the components in position. Using fixtures

could increase the accuracy level of the part.

The assemble parts were carefully welded

together.Lastly the mounts for the air spring

that have been laser cutare welded to the

finished arms. For the fabrication to be fully

completed, the completed arms are coated

with primer or paint to prevent the onset of

rust.

REFERENCES

• International Journal of Scientific &

Engineering Research, Volume 5,

ISSN


The pipes are cut to the specified length and bent

using CNC bending machine to the required angle. For

a ball joint at the wheel end,

manufactured with internal

which would support the ball joint

and allow for adjustability of the joint. Sleeves

of specified length are cut from the pipe to be

fitted to the arm at the chassis end. Nylon

bushes are used to prevent metal to metal

contact of the sleeve and the fastener. The bent

pipes are then notched at either ends according

to the angles at which the weld bunk and

. The welding of the

sleeves, weld bunks and pipes is the later stage

ss. This can be done

either manually or by using fixtures to hold

the components in position. Using fixtures

could increase the accuracy level of the part.

The assemble parts were carefully welded

Lastly the mounts for the air spring

n laser cutare welded to the

brication to be fully

completed, the completed arms are coated

with primer or paint to prevent the onset of

REFERENCES

International Journal of Scientific &


2455-7579


Issue 11, November-2014 258 ISSN

2229-5518 IJSER, Design, Analysis

and Fabrication of Rear Suspension

System for an All-Terrain Vehicle

• International Journal of Scientific &


Issue 3, March-2016 164 ISSN 2229

5518 IJSER © 2016

http://www.ijser.org .

• DESIGN AND ANALYSIS OF

SUSPENSION SYSTEM FOR AN

ALL TERRAIN VEHICLE.

• International Research Journal of

Engineering and Technology (IRJET)

e-ISSN: 2395-0056 Volume: 02 Issue:

07 | Oct-2015 www.irjet.net

2395-0072 © 2015, IRJET ISO

9001:2008 Certified Journal Page 759.

• Design, analysis of A-type front lower

suspension arm in Commercial vehicle

• International journal of engineering

research and technology (IJERT), Issn:

2278-0181, Vol-5,Issue09,September

16.Optimization and Effects of

Suspension Parameter on Front

Suspension of SAE Baja Vehicle using

ADAMS.

• LOTUS suspension analysis software

manual.

• IPASJ International Journal of

Mechanical Engineering (IIJME)

Volume 2, Issue 6, June 2014 Volume

2, Issue 6, June 2014 Design of double

wishbone suspension.

• International Journal of Mechanical

Engineering and Technology (IJMET

Volume 8, Issue 5, May 2017,

DOUBLE WISHBONE

SUSPENSION SYSTEM.

• Fundamentals of Vehicle Dynamics

byThomas D. Gillespie.


2014 258 ISSN

, Design, Analysis

ar Suspension

Terrain Vehicle.

International Journal of Scientific &


2016 164 ISSN 2229-

SER © 2016

DESIGN AND ANALYSIS OF

SUSPENSION SYSTEM FOR AN

.

International Research Journal of

Engineering and Technology (IRJET)

0056 Volume: 02 Issue:

2015 www.irjet.net p-ISSN:

0072 © 2015, IRJET ISO

2008 Certified Journal Page 759.

type front lower

suspension arm in Commercial vehicle.

International journal of engineering

research and technology (IJERT), Issn:

5,Issue09,September

Optimization and Effects of

Suspension Parameter on Front

Suspension of SAE Baja Vehicle using

LOTUS suspension analysis software

IPASJ International Journal of

Mechanical Engineering (IIJME)

e 2014 Volume

2, Issue 6, June 2014 Design of double

International Journal of Mechanical

Engineering and Technology (IJMET)

Volume 8, Issue 5, May 2017,

DOUBLE WISHBONE

Fundamentals of Vehicle Dynamics

• Automobile engineering by Kirpal

Singh.

• Theory of machines by R.S.Khurmi

• Suspension Dynamics Overview, RIT

Baja SAE India.

ISSN


Automobile engineering by Kirpal

Theory of machines by R.S.Khurmi.

Suspension Dynamics Overview, RIT

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