Go-Kart Design report

1. NKRC 2015
FINAL DESIGN REPORT
TEAM NEXUS RACING
SINHGAD ACADEMY OF ENGINEERING, PUNE.
PUNE, MAHARASHTRA.
ASHISH KUMAR
TEAM CAPTAIN
Prof. A. P. KALMEGH
FACULTY ADVISOR

2. Team Nexus Racing
Team id- NKRC15-076
Sinhgad Academy of Engineering Pune-411 048
Abstract-Team Nexus Racing aims at designing and fabricating
an eco-friendly kart having high fuel economy and maximum
driver comfort without compromising on kart performance.
The goals of the team also include to design kart for the
performance and serviceability. Compliance with the rulebook
of NKRC 2015 is compulsory and governs a significant portion
of the objectives. The aspects of ergonomics, safety, ease of
manufacture, and reliability are incorporated into the design
specifications. Analyses are conducted on all major components
to optimize strength and rigidity, improve vehicle performance,
and to reduce complexity and manufacturing cost.The design
has been modelled in Pro-E 5.0 and Creo 2.0 and the analysis
was done in ANSYS 14.5 and rendering was done using
SOLIDWORKS.
I.INTRODUCTION
The Go kart has been designed by team Nexus Racing
consisting of under-graduate students from the Sinhgad
Academy of Engineering affiliated to the University of Pune.
The Team Nexus Racing began the task of designing
by conducting extensive research of each main assembly and
components of the kart. The entire kart is designed by
keeping in mind that it should be able to withstand the racing
conditions without failure. Each component has been
considered to be significant, so the kart could be designed as
a whole trying to optimize each component while constantly
considering how other components would be affected.
Taking cost as a major parameter, the entire vehicle is
designed to integrate the usage of standard parts reducing
manufacturing cost. Combining this design methodology
with the standard engineering design process enabled us
to achieve a perfect match of aesthetics, performance, and
ease of operation.
Technical specifications
Table 1- Specifications of kart
Expected vehicle performance-
3D view of the vehicle
Fig. 1-Isometric view
Bajaj Discover 125ST engine
Displacement 125cc
Max. Torque 11.8 N-m
Max. Power 12.8 bhp
Chassis
Type Ladder Type
Weight 18 kg
Material AISI 1018
No. of welds 47
Weld length
Pipe OD
(mm)
Thickness
(mm)
Primary Member 31.75 1.65
Secondary Member 25.4 1.65
Vehicle dimensions
Wheelbase 42”
Front track width 36”
Rear track width 38”
Ground clearance 1.3”
Total weight 150 kg
Steering
Type Rack and pinion 11”
Transmission
Gearbox Bajaj Discover ST 5 speed
gearbox
Type Chain drive
Shifter Manual and Pneumatic
Brakes
Type Hydraulic
Max. Speed 80 kmph
Max acceleration 5.43 m/s2
Max deceleration 12.21 m/s2
Power to weight ratio NA
Net weight 102 kg
Gross weight 150 kg

3. Fig.2-Front view
Fig.3-Top view
Fig.4-Right view
Roll cage design
The development of design is explained below in this
section. For keeping CG of cart low the kingpin points are
kept at relatively higher plane also the nose is inclined
downward for better aerodynamic advantages. Pipes of
different cross sectional area are used for weight reduction.
Steel AISI 1018 has been selected as a material having cross
sections in accordance to the rules specified in the NKRC
2015 rulebook. All the bends are of constant radius. The
bumpers are so designed that they will serve as protection
from front and rear and will also add impressive look to the
kart.
Table 3-Properties of AISI1018
Design methodologies
Step 1: Drivers seating posture
Fig 5- driver
Following parameters are considered according to driver size
for the starting of design of chassis.
Table 4: Design parameters
Steering wheel height from ground 10”
Steering rod inclination 700
Step 2: Engine compartment
Fig 6- Bajaj Discover 125ST engine
Overall engine dimensions 16.5”x12.5”x10.5”
Step 3: CAD model of chassis
Density 7860kg/mm2
Ultimate strength 310 Mpa
Yield strength 410 Mpa

4. Step 4: Making the prototype
Fig 8- Prototype of PVC pipes
After making prototype, it was found that the distance
between driving and driven sprocket was less. It was
rectified by moving driver seat and engine forward.
Accordingly, changes were made in CAD model.
Step5: Finite Element Analysis of chassis
Fig 9- deformation due to front impact
For the front impact , slightly more deformation was noticed.
Therefore cross member was added to the nose.
Step 6: Finalizing the chassis according to driver ergonomics
Fig 10- CAD model of final chassis
Step 7: Final CAD model of kart
Fig 11- assembled CAD model of kart
FEA analysis of chassis
FEA analysis is done using ANSYS. The test results
showed that the deflection was within the permitted limit.
Meshing:
Auto meshing has been done in ANSYS 14.5 software.
Fig 12- auto meshing in Ansys 14.5
Following data has been found during preprocessing of
chassis.
• No. Of Nodes = 866517
• No. Of Elements = 435289
Front Impact:
For the front impact, engine and driver load were given at
respective points. The kingpin mounting points and rear
bumper kept fixed. To properly model the impact force, the
deceleration of the vehicle during impact needed to be
found. From impulse momentum equation, 6g force has been
calculated. The loads were applied only at front end of the
chassis because application of forces at one end, while
constraining the other, results in a more conservative
approach of analysis. Time of impact considered is 0.2
seconds as per industrial standards.
F x t = m x (Vi-Vf)
F x 0.2 = 200 x (11.12 -0)
F=11.2 KN
Fig 13- deformation
Fig 14-Von-Mises stress

5. Side Impact:
For side impact analysis the vehicle was kept static for
simplicity.Time of impact considered is 0.2 seconds as per
industrial standards. Impact force was applied by
constraining left side of chassis and applying load equivalent
to 3g force on the right side.
F x t = m x (Vi-Vf)
F x 0.12 = 200 (5.56-0) = 5.6KN
Fig 15- deformation
Fig 16-Von-Mises stress
Rear Impact:
Considering the worst case collision for rear impact, the
value of 6g force has been calculated. Load was applied at
rear end of the chassis while constraining front end and king
pin mounting points. Time of impact considered is 0.2
seconds as per industrial standards.
F x t = m x (Vi-Vf)
F x 0.2 = 200 x (11.12 -0)
F=11.2 KN
Fig 17- deformation
Fig 18-Von-Mises stress
Roll over:
The roll over analysis has been done by considering total
weight of kart applied over the top surface. The bottom
members are constrained.
F=m x g = 200 x 9.81=1962 N
Fig 19- deformation
Fig 20-Von-Mises stress
Max. deformation 3.6 mm
Max. stress 378 Mpa
FOS 1.05
Max. deformation 3.6 mm
Max. stress 378 Mpa
FOS 1.05
Max. deformation 3.6 mm
Max. stress 378 Mpa
FOS 1.05

6. Modal analysis:
Modal analysis was carried out for chassis and frequency of
vibration was found to be less than desired engine
frequency. The frequency of first 6 modes is almost zero,
therefore remaining modes have been shown below. The
minimum frequency of vibration for engine is above 800 Hz.
So the resonance will not occur. And thus design is safe.
Fig 23- modal analysis
Fig 24- graph of frequency obtained from modal analysis
Post processing:
After doing the various analyses it was concluded that
chassis is slightly weak for front impact and roll over.
Therefore a diagonal member has been added to the nose
and another diagonal member to rolling hoop. This gives the
better strength and makes chassis stiff.
Steering system:
The steering system for the vehicle has been designed to
provide maximum control of the vehicle. Along with
controlling the vehicle, the steering system has to provide
good ergonomics and should be easy to operate. After
researching multiple steering systems, the rack and pinion
type was selected which provides easy operation, requires
low maintenance, provide excellent feedback and is cost
effective. The positive 7 degree caster gives required
feedback and also the dynamic camber change with steering
thus assisting cornering.
Ackerman steering mechanism has been selected for steering
system because it does not slip during the turning of tires
and it reduces the steering efforts. The Ackerman efficiency
has been found to be 99.75%.
For the ergonomics, the 11” steering rack has been selected
to have a ratio high enough to quickly steer the wheels but
low enough that the driver has control of the car at all times.
Fig 25-CAD Model of our steering system
Knuckle
The alloy steel 4140 has been selected for the design of the
knuckle. Force equivalent to load of front tires, cornering
force of 1.2g magnitude and kingpin movement were applied
to respective points while constraining the stud in all the
directions. For worst condition, the deformation and stresses
are as follow.
Fig 26- deformation of steering knuckle
Fig 27- Von-Mises stress of steering knuckle
Max. deformation 0.8527 mm
Max. stress 275.75 Mpa
FOS 1.50
Max. deformation 3.6 mm
Max. stress 378 Mpa
FOS 1.05

7. Specifications of steering system:
Steering system Rack & pinion
Steering mechanism Ackerman
Camber angle 00
Castor angle 70
Kingpin inclination 150
Ackerman angle 18.890
Front track width 36”
Min. turning radius
1.95 m at 15
kmph
Outer wheel angle 30.800
Inner wheel angle 23.170
Steering efforts 51 N
Brake system:
According to rule book of NKRC 2015 the vehicle
travelling at 40kmph should stop when you apply the brake.
A hydraulic disc brake has been chosen as a suitable way to
accomplish these requirements. The discs of diameter
180mm, which is operated by 2 piston calliper hydraulic
braking system has been selected according to vehicle
design demands. The discs are mounted on the rear axle as
shown in figure below. Master cylinder is placed front side
of the vehicle beside the steering column for easy
maintenance.
Fig 28- braking system
Fig 29-brake pedal and master cylinder.
The master cylinder of TVS Apache has been selected on the
basis of various parameters. It has diameter of 19.05 mm.
The pedal ratio is 6:1.The deceleration of 1.25g has been
evaluated. Material for the brake disc is grey cast iron. The
thermal analysis if brake disc is given below.
Fig 30-Thermal analysis of brake disc
Max. heat flux generated 0.8509 W/mm2
Max. Temp. generated 93. 7590
C
Braking specifications
Type Hydraulic disc brakes
Disc outer diameter 180 mm
Disc inner diameter 130 mm
Mean effective diameter 171.8
Paddle ratio 6:1
Fluid line pressure
generated
20.1 bar
Torque required to stop the
vehicle
121.88N-m
Paddle force applied 100 N
Stopping distance 5.05 m at 40kmph
Transmission system:
Axle design-
Rear axle is used to transmit the power from engine to the
rear tire through chain drive. It is the solid shaft of diameter
32mm and length of 38” according to design calculations.
The material used is EN19 which is in British designation
.The specification and the properties of the material is given
below. It is the medium carbon steel with improved strength
over mild steel and it is easily machineable at supplied
condition and it gives the hardness approximately 58
Rockwell.

8. PROPERTY VALUE
Ultimate tensile strength 585 Mpa
Yield strength 515 Mpa
Hardness 58 Rockwell
Elongation 16%min
Density 1.20014e^-06Kg/mm3
Poisson’s ratio 0.4
Young’s modulus 4.00034e^+06 KPa
CHEMICAL COMPOSITION
Chemical Content
Carbon 0.35-0.45%
Phosphorus 0.06%
Manganese 0.60-1.00%
Sulphur 0.06%
Silicon 0.05-0.35%
Fig 31- Rear axle
Engine
As per NKRC - 15 rulebook, single cylinder four stroke 125
cc engine has to be selected. So there were number of
options for the selection of engine such as Honda shine,
Bajaj discover, TVS Flame, TVS Phoenix etc. After long
research work and survey we were left with two engines to
be selected. They have been compared on the following
basis and Bajaj Discover 125 ST engine is selected.
We have to use the inbuilt gear box that is manual 5 speed
constant mesh gear box, with the multi plate wet clutch we
are using which is inbuilt in engine. So our design is
according to the engine specification.
Fig 32-engine
Type
4 stroke, single cylinder
engine
Capacity 125 cc
Primary reduction 3.08
1st
gear reduction 2.71
2nd
gear reduction 1.78
3rd
gear reduction 1.31
4th
gear reduction 1.04
5th
gear reduction 0.91
Max. torque 11 N-m
Max. RPM 14000 rpm
Cooling system
As our engine is air cooled according to the given
specification of NKRC - 15. So for better air cooling we
have provided space in firewall support Which will gives us
better air cooling.
Chain drive
For this system, chain drive type transmission is most
preferable as it is easy to install, simple in design and cost
effective. The chain type used is of roller chain and pitch of
chain is decided from power rating table. The following
figure illustrates design power versus maximum rpm graph.
Following parameters are considered during selection of
chain.
Fig 33- KW rating vs speed
After interpreting the chain data, numbers of teeth on driving
sprocket are decided according to application and power of
engine. The secondary gear reduction is calculated on the
basis of maximum rpm. The driven sprocket should possess
in order to run the kart at top speed of 80 kmph considering
Parameter Discover Phoenix
Max. Torque 11.8 N-m 10.8 N-m
Max. Power 13 PS 11 PS
Fuel economy 68 kmpl 75 kmpl
Weight 22 kg 18 kg
Overall dimensions 16.5x12.5x10.5 15.8x12.1x10.8
Price 25 000/- 36 000/-
Gearbox 5 speed 4 speed

9. the transmission efficiency and manufacturing deficiencies
and maximum rpm available at the driving sprocket. From
the analytical calculations, 1.96 is the tabulated value of
secondary reduction ratio. Deciding odd number of teeth on
the both sprockets and even number of chain link in order to
avoid offset link, we get following values.
Table no 5- specifications of chain drive system
Chain
Max. torque at rear axle 170.8 N-m
Shock factor 1.5
KW rating 35.5 KW
Chain no 10B
Chain pitch 15.875 mm
Roller seating radius 5.1 mm
Centre distance 151.6 mm
Length 666.42 mm
No of links 42
Velocity 9.82 m/s
Max. Tension 2300 N
Driving sprocket
No of teeth 15
Pitch circle diameter 76.35 mm
Tooth thickness 9.182 mm
Tooth flank angle 28 mm
Wrap angle 136.40
Driven sprocket
No of teeth 29
Pitch circle diameter 146.82 mm
Tooth flank radius 32 mm
Wrap angle 148.50
The sprocket hub is designed on the basis of torsional failure
case and shear failure case. Material chosen is Aluminium
7075 T6 for its extensive shear strength and light weight.
The bolts are designed on the basis of shear as well as
crushing failure case.
Aluminium 7075 T6
Ultimate tensile strength
Yield tensile strength
Density
Sprocket Hub
Inner diameter 25 mm
Outer diameter 60 mm
Length 60 mm
Flange diameter 75 mm
Flange thickness 8 mm
No of bolts 4
Diameter of bolt 6 mm
Weight 1.8 kg
Wheels and tires
The tires have been selected in such a way that rear tires will
provide maximum traction as well as acceleration whereas
front tires will provide smooth steering effort and easy
cornering. Therefore, rear tire needed to be wider than front
tire. The diameter of tires must be as minimum as possible
maintaining ground clearance of 1”. Considering all these
requirements, cost and availability and weather conditions of
the event, wet slick tires of GOODYEAR manufacturer have
been selected. The available standard size of tires and rims
are as shown in table below.
GOODYEAR TIRES
Type Wet slicks, 4 ply. Radial
Front tire 12x125x5
Rim 5”, pcd 95 mm, bolt diameter 10 mm
Rear tire 14x300x8
Rim 8”, pcd 95 mm, bolt diameter 10 mm
Aspact
ratio
56%
Wheelhub
The wheel hubs are designed as per standard rim size and
analytical calculations have been done on the basis of shear
failure and torsional failure. The material selected is
Aluminium 7075 T6 due to its extensive strength, light
weight and optimum cost.
Exhaust system-
The design of exhaust needed to be in such a way
that it should be lighter in weight and should have minimum
resistance to gas flow (back pressure) and keeping it within
the limits specified for the particular engine model and rating
to provide maximum efficiency. Reducing exhaust noise
emission to meet local regulations and application
requirements. Providing adequate clearance between exhaust
system components and engine components, machine
structures, engine bays, enclosures to reduce the impact of
high exhaust temperatures on such systems. According to
space constrain, expansion factor has been decided to be 60.
The muffler is designed in such way that sound wave should
travel in a maximum path shifting phase change by 180o
.
Diameter of pipe 35 mm
Length of pipe 584.6 mm

10. Muffler
Diameter 150 mm
Length 424 mm
Diameter of
perforating holes
2 mm
Porosity 2.71*10
-11
No of holes 1040
Innovation:
Pneumaticc gear shifter
During deciding the topic of innovation the focus was on
how to improve the lap timings during endurance test. Then
we come to button type gear shifter mechanism. This
mechanism will reduce the time required to shift the gear
and will also maintain the concentration of driver over the
race.
Principle-
It works on the simple pneumatic circuit.Connections are as
shown in fig
Working-
It consists of double acting pneumatic actuator.Shifting of
gears will be controlled by the motion of the actuator.It
consists of buttons on the steering wheel for actuation of the
actuator .Circuits for the actuation of Up shift and Down
shift are shown in the fig
Electricals-
Two kill switches are located at dashboard and at the right
side of the driver.
In case of accidental case one kill switch is placed at the
back side of firewall to have easy externals access.
Brake light is mounted on the fire wall which is clearly seen
by rear vehicles.
Ergonomics and safety
1. Compact cockpit which is comfortable yet safe.
2. Ricardo seat used along with rubber dampers and
neck support for comfort as well as lightness.
3. The pedal position is ergonomically compatible
with the driver’s driving style.
4. The dashboard mounted kill-switch is in ease of
access to the driver in case of accident.
5. Steering wheel is kept of oval shaped to have space
and ride comfort for driver.
6. The fire-extinguisher as well as rear kill-switch is
easily accessible in case of emergency.
Aesthetics-
1. The kart is so designed that every sub-system
is visible from outside.
2. Well balanced surfaces and elegant curves
contributes to an impressive look.
3. Front nose represents the grandness and adds
flamboyancy to the kart.
4. Single tone coloring scheme of black color
combination with Gold colored frame adds
stylish.

11. ACKNOWLEDGMENT
TEAM NEXUS RACING would like to thanks Virtulis
Motorsports who made platform to present our talent and
engineering skills and we are also like to thanks our
mechanical engineering department of Sinhgad academy of
engineering, Pune.
REFERENCES
1. The race car dynamics by Millikan.
2. Chassis engineering by Adams Herb.
3. Machine design by R. S. Khurmi.
4. Fundamentals of vehicle dynamics by Thomas
Gillespie.
5. Rulebook of NGKC by ISNEE www.
Isnee.in/ngkc2014
6. Design of machine elements by V.B. Bhandari
7. www.zigwheels.com
8. Automobile engineering by kripal singh.
9. www.howstuffworks.com
10. www.gforces.net
1) ASHSHKUMAR
TEAM CAPTAIN
EMAIL: ashishk.0411@gmail.com
2) Prof A. P.KALMEGH
FACULTY ADVISOR
EMAIL: ajaykalmegh@rediffmail.com