IJSRD - International Journal for Scientific Research & Development| Vol.

7, Issue 07, 2019 | ISSN (online): 2321-0613

Design, Analysis and Fabrication of Suspension System of an All- Terrain

Vehicle
Mr. Vijay Zarkar1 Mr. Vaishnav Saykar2 Mr. Vedang Sharma3 Mr. Kshitij Sable4
1,2,3,4
Department of Mechanical Engineering
1,2,3,4
PCET’s Pimpri Chinchwad College of Engineering and Research, Ravet, Pune 412101, India
Abstract— The main objective of this paper is to design, The suspension system works together with the tires,
analyze and fabricate a double wishbone suspension system wheels, frame, suspension linkages, wheel hubs, brakes
for an All- Terrain Vehicle for SAE BAJA INDIA systems as well as steering system to provide driving comfort,
competition. The suspension system comprises of wishbones, stability, etc. This system is the mechanism that physically
shock absorbers, springs, wheel assembly, and ball-joints. separates the vehicle body from the wheels of the vehicle [2].
The suspension system supports the sprung mass of the The study of a vehicle's suspension can be broken
vehicle. It also absorbs the shocks and vibrations arising from into two major categories: suspension kinetics and suspension
the rough terrains and roads. It is responsible for the safety of kinematics. Suspension kinetics is a dynamic and vibration
a vehicle during its maneuver. It also serves the dual purpose analysis on the vehicle and suspension systems. Suspension
of providing stability to the vehicle while providing a kinematics involves analyzing the motion of the tires as the
comfortable ride quality to the occupants. Nowadays, modern suspension compresses and extends [1]. This paper mainly
automobiles are incorporating the active and semi-active type focuses on the suspension kinematics. In general, there are 2
of suspension system. Due to cost restrictions, the type of types of suspension systems; solid axles and independent
suspension is the passive type. During the design, the focus suspensions. In solid axle suspension systems, the movement
was more on weight and cost optimization. This paper of one wheel affects the other wheel causing it to move
proposes a method for the design of wishbones, shocks, wheel together. Thus, the motions of the two wheels are correlated
assembly. Double wishbone A-arm suspension was chosen to one another. This was an old system wherein there were
for front and H- arm suspension was chosen for the rear. The many vibrations. Independent suspension systems allow the
design of the components was done on CATIA V5 R21. It left and right wheels to move independently; the movement
included the design of wishbones, wheel knuckle and wheel of one wheel will have no effect on the other wheel. The
hub. All the components were rigorously analyzed on advantages of an independent type of suspensions are: they
ANSYS Workbench 19.1. It included the static structural provide better resistance to vibrations; they provide high
analysis of all the components. The dynamic characteristics suspension roll stiffness; steering geometry is easily
of the system were analyzed on simulation tools. The output controlled; suspension geometry is easily controlled, and they
characteristics of the passive system (without variable length allow for higher wheel travel. The major disadvantages are:
arms) were validated on LOTUS software. In LOTUS, the camber angle changes quite a bit over suspension travel;
various geometries like camber, caster, and kingpin increased unsprung mass; and the high cost of the system [1].
inclination were set accordingly. After the CAE of In the designing process, suspension geometry plays
components, a material survey was done and apt material was a very vital role. There are few terminologies related to
chosen. Wishbones were fabricated and wheel assembly was geometry and dynamic handling of the vehicle. Following are
done on VMC. Hence, this provides the scope for an those:-
optimized and durable performance of the suspension system. 1) Camber- The camber angle is defined as the inclination
Keywords: All- Terrain Vehicle, Wishbones, Suspension of the tire with respect to the road surface in the vertical
system, Shock absorbers, Knuckle, Hub, A-arms Lotus plane (when looking at the vehicle from the front view).
A negative camber occurs when the top of tire points in
I. INTRODUCTION towards the vehicle, and a positive camber occurs when
Automobiles are classified into different classes based on the top of the tire points out away from the vehicle
their utility. It generally includes a sedan, all-terrain vehicle, (chassis). Camber on a wheel will produce a lateral force
truck and jeep. A normal automobile consists of millions of which is known as camber thrust [1].
components. Further, they are segregated into different sub- 2) Caster- The caster angle is defined as the angle between
systems on the basis of their intended functions. The different the steering axis and the vertical plane viewed from the
sub-systems include chassis, engine, transmission, steering, side of the tire. The caster angle is positive when the
suspension, and brakes. The paper deals with the design, steering axis (the steering axis is defined as a line that
analysis, and fabrication of a suspension system of an All- passes through the ball joints on the upper and lower
Terrain Vehicle. The primary function of the suspension control arms) is inclined in such a way as it points to the
system of the vehicle is that it should fulfill primary front of the vehicle. It is important that the caster angle
requirements like maneuverability and stability, safety. The and caster trail be positive because both of these
suspension system of the vehicle should perform multiple quantities will affect the aligning moment [1].
tasks such as maintaining the contact between tires and road 3) Toe- The toe angle is defined as the angle between the
surface, providing the vehicle stability, protecting the vehicle longitudinal axis of the vehicle and a line passing through
chassis from the shocks excited from the unevenness terrain, the center of the tire when viewed from the top. Toe in
etc. occurs when the front of the tire points in towards the
vehicle, and tow out occurs when the front of the tire
points away from the vehicle [1].

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4) Kingpin inclination- The kingpin angle is the angle considered as the camber angle which is not affected by the
between the steering axis and the vertical plane when rolling of the vehicle body. Therefore, it produces little
viewing the tire from the front. A positive kingpin angle camber in cornering, except for that which arises from
occurs when the steering axis points outward. The effect slightly greater compression of the tires on the outside of the
of a positive kingpin angle is to raise the wheel as the turn. In addition, wheel alignment is readily maintained,
wheel is turned about the kingpin axis. The greater the which contributes to minimize tire wear. The disadvantage of
kingpin angle is the more the wheel will rise as it is being solid steerable axles is their susceptibility in shimmy steering
steered [1]. vibrations, heavy mass, etc. The most types of solid axles are
5) Instant center and roll center- The instant center is the Hotchkiss, Four links and De Dion. The independent
point the wheel rotates about relative to the vehicle suspension system, allows one wheel to move upward and
chassis. It is a function of the geometry of the suspension downward with a minimum effect on the other wheel. Most
system. The instant center is important because it defines of the passenger cars and light truck use independent front
the position of the roll center. The roll center position is suspension system because provide much more space for
a position where the lateral forces developed at the installing vehicle engine, allow much more displacement of
wheels are transmitted to the vehicle sprung mass. This the wheel, better resistance in steering vibration (wobble and
point will affect the behavior of both the sprung and shimmy) as well as offer higher performance in passenger
unsprung mass and thus effects the vehicles cornering comfort. As disadvantages of the independent suspension
characteristics. The roll center is defined as the point in system can be considered the complexity of the design and
the transverse vertical plane where the lateral forces may manufacturing cost due to an increasing number of parts.
be applied to the sprung mass without producing any Over the years, many types of independent suspension
suspension roll [1]. systems have been tried to develop such as MacPherson,
double wishbone, multi-link, trailing arm, and swing axle.
II. LITERATURE REVIEW I. P. Dhurai [3] describes the kinematics of the
William Bombardier et al. [1] have given a precise vehicle is nothing but how the vehicle behaves as it traverses
description regarding the design of suspension system for an through a range of obstacles and bumps. Suspension-
ATV. The topic is been divided into two major sections: parameters like camber, toe, caster, kingpin inclination,
Suspension Kinetics and Suspension Kinematics. The first motion ratio, and scrub radius affect the kinematic
part emphasizes mainly on the dynamic and vibrational performance. These parameters affect the orientation of the
analysis whereas the latter involves analyzing the wheel wheels with respect to the ground which affects the handling
motion on road surface. Roll center is the virtual point of the characteristics of the vehicle. It's is necessary to provide the
vehicle around which the vehicle tends to roll. It is very optimum range of values for these parameters to keep the tires
essential to locate the roll center at an optimum height so that in contact with the ground and also to prevent the tire from
the dynamic handling of the vehicle improves. Also the wear. The optimization of the kinematics of suspension was
instantaneous center of the double wishbones plays an performed with the help of MSC Adams and Solid Works. A
important role in determining the roll center of the vehicle. CAD drawing of the front suspension was drawn considering
All the co-ordinates of the suspension joints, pivot points and the vehicle parameters, then these hard points were imported
the shock mounting points are carefully analyzed in the into the ADAMS/Car software and the analysis was
software named Lotus. The changes in the suspension performed. In order to provide a wheel travel of 5 inches
geometry during the wheel motion should be within the during a bump and 4 inches during rebound motion ratio of
permissible limits. Apart from this, the tie rod length and 0.5 was chosen. Motion ratio or Linkage ratio is the ratio of
position should be mounted in such a way that the assembly spring travel to that of the wheel travel. Reducing the motion
remains uncomplicated. The motion ratio describes the ratio increases the travel but it increases the forces acting on
amount of shock travel for a given wheel travel. As the the wishbone or lower A-arms. So the lower wishbone should
motion ratio decreases the control arms will have to be built be structurally optimized with FEA analysis. The pro-dive
stronger because the effective bending moment acting on geometry of 30% on the front was incorporated in order to
them will increase. The effective bending moment will transmit the forces to the shock effect and it also provides a
increase because the moment arm will increase. The front ride small amount of recessional (longitudinal) wheel travel
rate should be 30% lower than the rear ride rate. The .However it causes a large number of forces to be transferred
suspension shocks are one of the first things that need to be to the front during braking. ADAMS/Insight was used in
determined because the suspension geometry is dependent on order to reduce the time of the iterative process. Once the
them. The motion ratio needs to be determined such that the desired roll centers are inputted, ADAMS/insight iterates
desired wheel travel will not bottom out the shocks. only the selected hard point’s location to provide the optimal
Shpetim Lajqi et al. [2] have mentioned in his paper location of these hard points. So the final points were
that the dependent suspension system is also known as a solid determined through the iterative process conducted by
axle when both wheels (left and right) are mounted the same ADAMS/Insight and the graphs for the suspension
solid axle. In this case, any movement of any wheel will be parameters were obtained
transmitted to the opposite wheel causing them to camber Shocks are one of the important components of the
together. Solid drive axles usually are used on the rear axle of suspension system. The function of a Shock is to transmit and
many passenger cars, trucks and on the front axle in many absorb the forces generated in the tire due to the rough road
four-wheel drive vehicles. The advantage of solid axles is condition. It works by converting the kinetic energy absorbed
from the wheel's motion to heat. Shocks usually consist of

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two parts, one is spring and the other is the damper. The shock dampers contain high-pressure nitrogen gas and FOX
spring portion of the shock is only capable of absorbing the high viscosity index shock oil separated by an Internal
shock and load of the vehicle whereas damper dissipates the Floating Piston system. This helps to ensure consistent, fade-
energy stored in the spring and reduce the vibration. The free damping in most riding conditions.
chosen shock for the Baja vehicle is usually Fox Float 3
where the coils are replaced by air springs; hence it has an III. OBJECTIVE AND METHODOLOGY
infinity adjustable spring rate. However, the damping of the The objective of the paper is to design, analyze and fabricate
shock cannot be modified. the suspension system for an All- Terrain Vehicle. The
These shocks are made of 6061-T6 aluminum in objectives are as follows:-
order to reduce the weight and increase the strength of the 1) A detailed study of the suspension system of a vehicle.
shock. Air shocks are generally progressive, that is the force 2) Selecting optimum parameters to make the system more
required to compress the shock increases exponentially. So efficient.
for a small bump, the shock provides sufficient travel and 3) Weight reduction
keeps the driver comfortable. For a large bump or fall of the 4) Cost reduction
vehicle, the shock travels progressively and it prevents the 5) Reducing the complexity in fixture manufacturing for
vehicle from bottoming out. The spring rate of air shocks are wishbones.
dependent on their air pressure.so in order to determine the 6) To support the steering system by keeping the tire in
air pressure, the values were extrapolated from the spring rate contact with the terrain.
curve. A motion ratio of 0.5 was selected to get more travel. The methodology adopted is as follows:-
The spring rate data given in the Fox shock manual was 1) Complete and detail study about the topic.
inputted in the ADAMS curve manager and simulation was 2) Identifying the pros and cons of the system and also
performed. highlighting the areas where improvements are possible.
Abhilash Gunaki et al. [4] state the procedure to 3) Calculating the pre-requisite parameters and making the
determine the roll center of the double wishbone suspension proper assumptions of certain parameters to start the
system. Roll center in the vehicle is the point about which the design.
vehicle rolls while cornering. There are two types of roll 4) Designing the suspension geometry in CAD. Plotting the
centers the geometric roll center and force based roll center. ICR's of the system, roll center, line diagram of
The roll center is the notional point at which the cornering wishbones and suspension parameters like caster,
forces in the suspension are reacted to the vehicle body. The camber, KPI, tire dimensions.
location of the geometric roll center is solely dictated by the 5) Importing the same geometry in LOTUS software. It is
suspension geometry and can be found using principles of the software used to analyze the suspension geometry along
instant center of rotation. The determination of roll center with the wheel travel. All the parameters can be
plays a very important role in deciding the wishbone lengths, controlled by using this software by using the trial and
tie rod length and the geometry of wishbones. Roll center and error method.
ICR is determined because it is expected that all the three 6) Once the geometry is finalized, then the design of the
elements- upper wishbone, lower wishbone and tie rod should wishbone is started. This step includes calculating the
follow the same arc of rotation during suspension travel. This loads acting on wishbones, calculating vehicle inertia
also means that all three elements should be displaced about forces, cornering forces, anti- dive, anti-squat
the same center point called the ICR. Initially, wishbone percentage. Design the components on CAD.
lengths are determined based on track width and chassis 7) Analyze the CAD designs for proper loads and end
mounting. These two factors- track width and chassis conditions in CAE software. Also, make necessary
mounting points are limiting factors for wishbone lengths. changes if any heavy stress concentrations are found in
Later, the position of the tire and the endpoints of the upper the design.
arm and lower arm are located. The vehicle center line is 8) Selection of proper dampers for the vehicle.
drawn. The endpoints of wishbones are joined together to
visualize the actual position of the wishbones in steady
IV. DESIGN DESCRIPTION
condition. When the lines of upper and lower wishbones are
extended, they intersect at a certain point known as After a considerable study, we selected to go with a double
Instantaneous Center (ICR). A line is extended from ICR to a wishbone unequal and non- parallel A-arm suspension for the
point at which tire is in contact with the ground. The point at front and H arm suspension with a camber link at the rear.
which this line intersects the vehicle center line is called the The reason for selecting these types of suspension was as
Roll Center. Now, extend a line from ICR point to the steering follows:-
arm. This gives exact tie rod length in order to avoid pulling 1) Independent system
and pushing of the wheels when in suspension. 2) Simpler design
Owunna Ikechukwu et al. [5] explain the Fox Float 3) It gives freedom to assign various parameters.
3 Evol R high- end shocks. FOX FLOAT (FOX Load 4) Greater adjustability
Optimizing Air Technology) 3 EVOL R air shocks are high- 5) Easy to fabricate and assemble.
performance shock absorbers that use air as springs, instead 6) Lesser service time.
of heavy steel coil springs or expensive titanium coil springs. 7) Higher strength to weight ratio.
Underneath that air sleeve is a high-performance, velocity- 8) Better steering control.
sensitive, shimmed damping system. FLOAT 3, EVOL R air

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It is easy to amend the output of the system for Following is the table of initial assumptions in LOTUS
desired handling and comfort. It provides isolation from high- software:-
frequency vibrations that are caused due to tire vibration in
response to the road profile. The use of independent upper
and lower arms provides more flexibility and freedom to
adjust the parameters more precisely than a McPherson strut.
This independent arrangement allows for controlling
respective components of the system without affecting the
entire system on a drastic scale.
After assuming initial parameters like ride height,
wheel track, wheelbase, wheel travel, we plot the roll center
on the vehicle. For this, the roll cage design needs to be ready.
Below given is the procedure to plot the ICR and roll center
of the vehicle.
The roll center position is calculated differently for
each type of suspension system. The procedure for
calculating the roll center position will be outlined for the
double A-arm type of suspension only (if it is desired to learn
how to calculate the roll center position for a different
suspension system than it is advised to look in the vehicle
dynamics textbook). The first step is to locate the instant
center. This is accomplished by drawing a line that passes
through each of the A- Arms when looking at the vehicle in
the front view. The intersection of these lines represents the
instant center. The second step is to draw a line form the
center of the tires contact patch to the instant center. The point
where the line drawn in step two intersects the center line of
the vehicle represents the roll center position (Figure 4.1: Roll Fig. 4.3: 3D Parameters to be entered in LOTUS Suspension
center position of a double A-arm type of suspension) Analyzer
In figure 4.3, the data related to steering travel, front
braking percentage, front/ rear brake types are provided by
steering and braking departments respectively. In table 4.3,
the data of points such as the outer/ inner track rod ball joint
is given by the steering department. During analyzing it on
LOTUS, the suspension and steering department should work
in coordination so that all their components are placed
correctly.

Fig. 4.1: Roll center position of a double A-arm type of

suspension [1]

Fig. 4.2: Plotting roll centre in CATIA V5 R21 for BAJA

Fig. 4.4: Tire properties in LOTUS Suspension Analyzer
roll cage.

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Fig. 4.7: LOTUS 3D Bump results

Fig. 4.5: Front Suspension Co-ordinates 3D in LOTUS

Suspension Analyzer
All the above data is for front dual A-arm
suspension. For the rear, it is different. It varies according to
the type of suspension chosen behind. Once, all the
parameters are entered, the software analyzes it for the
dynamic conditions and gives us the results. In these results,
we mainly look for the changes occurring in various
suspension geometry angles. We also look out for the anti-
dive and the anti-squat percentage. The vehicle can be Fig. 4.8: LOTUS 3D Vehicle Roll results
simulated in all conditions of rolling, yawing and pitching.
By this, we get an overall idea of the roll center deviation
from the center. The results and the simulations are given
below.

Fig. 4.9: LOTUS 3D Steer results

V. FORCE CALCULATION ON THE FRONT SUSPENSION

A. Reaction force for the front from ground
= (Mass per wheel * 9.81)
= (200*0.35/2)*9.81
= 35*9.81
= 343.35 N
Fig. 4.6: LOTUS result (deviations in camber, caster, KPI)

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Where, Mk= 1/MR= 1/0.6= 1.6 15*103= 4π2* fr2*140*1.62

fr= 1.02 Hz
G. Ride rate
Vertical force 343.35
Ride rate= = = 1.37 N/mm
Vertical Displacement 250

H. Forces on rear knuckle & hub

1) Radial force
Weight on front: 35%
Fig. 5.1: Front lower wishbone loading diagram Weight on one knuckle= 200*0.35/2= 35 kg
By taking moment Hence, 5G force= 5*9.81*35= 1716.75 N
SF * 8.3157= 343.35 *17.551 2) Axial force
SF= 724.6738 N m= 35 kg; v= 16.66 m/s; r= 1.7m
Dynamic factor= 2.581 (assumed) m2
v 35∗16.662
Fc= = = 5714.38 N
Dynamic spring force= SF* 2.581= 1871.1 N r 1.7

VI. FORCE CALCULATION FOR REAR SUSPENSION

B. Spring stiffness
A. Reaction Force for Rear from Ground
Dynamic spring force 1871.1 N
Spring stiffness = = = 15 = (Mass per wheel * 9.81)
total spring deflection 74.35+50.39 mm
= (200*0.65/2)*9.81
C. Motion ratio = 65*9.81
1) For Bump Reaction force= 637.65 N
Shock travel 50.39 + 10
Motion ratio = = = 0.60
Wheel travel 100
2) For Rebound
Shock travel 74.35 + 10
Motion ratio = = = 0.56
Wheel travel 150
D. Motion ratio (according to Windsor report)

Fig. 5.5: Rear lower wishbone loading diagram

By taking moment
SF * 302.881= 637.65 *486.47
SF= 1024.25 N
Dynamic factor= 2.55 (assumed)
Dynamic spring force= SF* 2.55= 2611.58 N
Motion ratio= b1/ b2= 202.706/ 155.85+ 202.706= 0.56
B. Spring Stiffness
Dynamic spring force 2611.58 N
Spring stiffness = total spring deflection = 50.69+80.09
= 20
mm

C. Motion ratio
For Bump
Shock travel 50.69 + 10
Motion ratio = = = 0.61
Wheel travel 100
For Rebound
Shock travel 80.09 + 10
138.31 Motion ratio = = = 0.60
Motion ratio= b/ (a+b) = = 0.68 Wheel travel 150
138.31+64.263
2
E. Wheel rate= (MR )*(C)*(ACF) D. Motion ratio (according to Windsor report)
where, C= Spring rate
WR= 0.62*15*0.8660= 4.6764 N/mm
1 Ks
Now, SF= ∗√ = 1.647 Hz
2π Ms
where, Ks= Dynamic spring stiffness (N/ m)
Ms= Sprung Mass (Kg)
F. Ride frequency
Ks= 4π2* fr2*m*mk2 Fig. 5.6: Rear lower motion ratio (inclined distance)

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Motion ratio= b1/ b2= 302.881/ (94.689+302.881)= 0.76 VII. DESIGN OF COMPONENTS ON CATIA

Fig. 5.7: Rear lower motion ratio (straight distance)

121.362
Motion ratio= b/ (a+b) = = 0.59
121.362+81.838
Hence, we select the average motion ratio i.e., 0.64
E. Wheel rate (WR)

Fig. 7.1: Front lower wishbone

Fig. 5.8: Angle Correction Factor- rear

Angle Correction Factor (ACF) = cos (A)
= cos (9.46) = 0.9876
Wheel rate= (MR2)*(C)*(ACF)
where C= Spring rate
WR= 0.60962*20*0.9876= 7.05 N/mm
1 Ks
Now, SF= ∗√ = 1.92 Hz
2π Ms
Fig. 7.2: Front upper wishbone
where, Ks= Dynamic spring stiffness (N/ m)
Ms= Sprung Mass (Kg)
F. Ride frequency
Ks= 4π2* fr2*m*mk2
20*103= 4π2* fr2*140*1.672
fr= 1.30 Hz
G. Ride rate
Vertical force 637.65
Ride rate= = = 2.55 N/mm
Vertical Displacement 250

H. Forces on rear knuckle & hub

1) Radial force
Weight on front: 65%
Weight on one knuckle= 200*0.65/2= 65 kg
Hence, 5G force= 5*9.81*65= 3188.25 N
2) Axial force
m= 65 kg; v= 16.66 m/s; r= 1.7m
m2
v 65∗16.662
Fc= = = 10612.42 N
r 1.7

Fig. 7.3: Front right knuckle

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VIII. CAE OF COMPONENTS

The components are rigorously tested in the CAE software
for the real world conditions. The CAE is carried out in order
to optimize the design and check its strength and durability in
various conditions. In the below images, the results of
analysis from Ansys 19.1 are shown. Various forces like the
bump, centrifugal, braking, steering forces are taken into
consideration. The maximum stress induced in the
components is checked and the FOS is calculated. The mesh
used for analysis is 3D Tetrahedron mesh and the mesh size
varies between 2-4 mm. The type of analysis performed is
“static structural”. Considerable weight reduction is done
after properly analyzing the components. General procedure
followed for normal analysis in Ansys is as follows:-
1) Select the type of analysis (e.g. - Static Structural,
Thermal, Modal, etc.)
2) In Engineering Data, select the appropriate material from
the material library list.
3) Import the solid geometry from any CAD software to
Ansys with compatible file extension (.igs)
Fig. 7.4: Rear right knuckle 4) Set the mesh type and mesh size according to the
component and the forces acting on it.
5) Apply the constraints and the forces on the body of the
component.
6) Select a proper solver and solve the problem
7) Check and analyze whether the results obtained are in
permissible limits or not. Carry out further optimization
accordingly.
Following are the constraints required for various
components for analysis:-
A. Knuckle
1) Apply a fixed constraint to the area which is in contact
with the stub axle.
2) Apply the calculated bump force in an upward direction
on the lower and the upper ball joint mounting points.
3) Apply the braking force in opposite directions on both
the caliper mounting points.
Fig. 7.5: Front wheel hub 4) Apply the steering force on the steering arm mounting
points.
5) Apply the centrifugal force in the outward direction on
the upper ball joint mounting whereas in the inward
direction on the lower ball joint mounting point.
B. Wheel hub
1) Apply the centrifugal force in the outward direction on
the upper stud mounting point whereas in the inward
direction on the lower stud mounting point.
2) Apply the bump force in the upward directing on both the
upper and the lower stud mounting points.
3) Apply a fixed constraint to the area where the bearing is
mounted.
For the rear hub, apply the output gearbox torque as the drive-
shaft is connected to the rear side.

Fig. 7.6: Rear wheel hub

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Fig. 8.1: Front knuckle- Constraints and Forces

Fig. 8.6: Rear knuckle- FOS results

Fig. 8.2: Front knuckle- FOS results

Fig. 8.7: Rear hub: Constraints and Forces

Fig. 8.3: Front hub- Constraints and Forces

Fig. 8.8: Rear hub: FOS results

IX. MANUFACTURING
The type of welding done on the wishbone is Tungsten- Inert
Gas Welding (TIG). It is chosen due to its high-quality weld
and deep penetration. For fabricating the wishbones, the
Fig. 8.4: Front hub: FOS results fixtures are to be made first. The fixture is generally made up
of wooden plates. Fixtures are made in order to maintain
accuracy in the hard points of the wishbones and knuckles. If
these points deviate during manufacturing, then it totally
affects the suspension dynamic handling of the vehicle.
The material selected for wishbones is AISI 4130. It
is alloy steel with chromium and molybdenum as alloying
elements in small percentages along with carbon. The
knuckle and wheel hub is made up of Aluminium 7 series
material. The knuckle is manufactured on a 3 axis VMC. The
wheel hub is firstly processed on the CNC turning center and
later manufactured on a VMC. The stub axle is manufactured
on a conventional lathe or a CNC turning center. The bearings
Fig. 8.5: Rear knuckle- Constraints and Forces used in the assembly are of SKF. The bearing sizes are
properly designed and selected from the company catalog.
Nylon lock nuts and hardened fasteners are used to connect
the components.

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Fig. 9.1: Front upper wishbone fixture

Fig. 9.4: Front suspension assembly

Fig. 9.2: Wheel assembly-1

Fig. 9.5: Rear suspension assembly

X. RESULTS AND CONCLUSION

Intensive testing is done on the ATV on various terrains to
check its durability. Approximately, the vehicle is run for 350
Fig. 9.3: Wheel assembly-2
kilometers. Since the air shocks are used, there is a bit of trial
and error to be done to adjust the pressures in the shocks.
These pressures affect the dynamic handling of the vehicle.
Ball joints and rose joints are used to connect the knuckle to
the wishbones of front and rear respectively. They permit
more degrees of freedom for angular changes during the
motion. The wishbones are connected to the chassis with the
help of the tabs. These tabs are provided with stiffeners in
order to strengthen the joints. As no components are ever
accurately made, we too have variations in design and the
actual components. But, all that is within the permissible
limits.
In suspension, the hard points which are also known
as the connecting (mounting) points are very important. A
slight change can affect tremendously on the complete
system. Hence, the fixture is of utmost importance while

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 Design, Analysis and Fabrication of Suspension System of an All- Terrain Vehicle
(IJSRD/Vol. 7/Issue 07/2019/121)

manufacturing the wishbones. Provisions are made in order

to adjust the angles like camber and toe- in and toe-out. All
the components are modeled in software named CATIA V5
R21. All the analysis is done in Ansys 19.1. The LOTUS
Suspension Analyzer is used to simulate the results of the
suspension geometry. ADAMS is also one of the software
where we can actually simulate the suspension mechanism
according to varying terrain conditions.
Hence, it is very rightly said that figuring a
suspension of a car is almost entirely a matter of making
useful approximations. It is not an exact science, but neither
it is a blind application of thumb rules.

REFERENCES
[1] Bombardier, W., Fadel, A., Ding, X., Funkenhauser, I.,
Zuccato, B., Bowie, M., Tao, Y., Huang, B., Baja
Project- Suspension, Faculty of Mechanical, Materials
and Automotive Engineering, University of Windsor, 92-
420 Capstone II, 2007, pp. 15,32,35,38.
[2] Lajqi, S., Pehan, S., Lajqi, N., Gjelaj, A., Psenicnik, J.,
Emin, S., Design of Independent Suspension Mechanism
for a Terrain Vehicle with Four Wheels Drive and Four
Wheels Steering, Annals of Faculty Engineering
Hunedoara- International Journal of Engineering TOME
XI, ISSN 1584-2665, 2013, pp. 1.
[3] Dhurai, I. P., Optimization and Effects of Suspension
Parameter on Front Suspension of SAE Baja Vehicle
using ADAMS, International Journal of Engineering
Research and Technology (IJERT), ISSN: 2278-0181,
Volume- 5, Issue- 9, September- 2016.
[4] Gunaki, A., Acharya, C., Gilbert, S., Bodake, R., Design,
Analysis and Simulation of Double Wishbone
Suspension System, IPASJ International Journal Of
Mechanical Engineering (IIJME), Volume- 2, Issue- 6,
June- 2014.
[5] Ikechukwu, O., Aniekan, I., Ebunilo, P., Ikpe, W.,
Investigation of the Vehicle Tie-Rod Failure in relation
to the Forces Acting on the Suspension System,
American Journal of Engineering Research (AJER), e-
ISSN: 2320-0847 p- ISSN: 2320-0936, Volume- 5,
Issue- 6, 2016, pp. 208-217.
[6] FOX Float 3 Evol R manual
[7] Gawai, N., Design, Modelling and Analysis of Double
Wishbone Suspension System, IRD India IIJMER, ISSN
(Print)- 2321-5747, Volume-4, Issue-1, 2016
[8] Mr. Deshmukh, R., Presentation on Suspension Design
and Construction for All- Terrain Vehicle
[9] Bhandari, V.B., Design of Machine Elements, 3rd
edition, Tata McGraw-Hill Education (India) Pvt. Ltd.,
Delhi, 2014, ISBN-13: 978-0- 07-068179-8, ISBN-10: 0-
07-068179-1, India.
[10] Gillespie, T., Fundamentals of Vehicle Dynamics,
Society of Automotive Engineers, Inc., Warrendale.

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