Design of half shaft and wheel hub assembly for racing car

The Half - Shaft and Wheel Hub of Formula One racing car was designed taking into consideration one of the popular model of Redbull racing car. The various dimension of shaft and hub were altered to attain maximum factor of safety.

1. DESIGN PROJECT

2. DESIGN OF HALF –SHAFT AND REAR
WHEEL HUB ASSEMBLY OF A RACE CAR
Faculty coordinator
: Prof. GokulKumar
Design project guide
: Prof. B . K
Jha
Design project guide
: Prof. B . K
Jha
ManvendraSingh Inaniya(08BME126)
9047288146
Ravi Shekhar(08BME181)
9566810725

3. INTRODUCTION INTRODUCTION

4. Project Objective
•It was required to design a hub assembly and
half–shafts for the Formula 1 car of mass about
640 kg, maximum speed of 300 km/hr and
average speed of 150km/hr.
•The assembly must give stability during rotation
of the wheels. The weight and the dimension of
the hub must be as small as possible because of
the unsprungweight which further reduces the
rotational mass. The halfshafts should not fail
under stress.

5. Red Bull RB7 Formula 1 Car
RB7 F1 is the official car from World Champions Red Bull for the 2011 season of
Formula 1. We have considered this vehicle as a reference for this Design Project
as it is one of the fastest and most technologically matured vehicl e in the racing
scenario.

6. Half Shafts
•Ahalf shaftis anaxleon afront wheel
drivevehicle connecting the transmission to
the driven wheels. the driven wheels.
•Therear wheel drivenFormula 1 vehicle
being observed for the project uses half shafts
in rear, as the differential is rigidly mounted
and anindependent rear suspensionis used.

7. Design Consideration
Half shafts are designed as
–a hollow metal tube to reduce weight.
–CV jointat either end, allowing the driven wheels
to maintain constant velocity . to maintain constant velocity .
–Splinesto transmit power between differential, CV
joints, shaft and wheel hub.
–thesuspensiontravels during driving.
–fatigues due to high speed rotation.

8. WheelHub
•A hub assembly contains the wheel bearing,
and the hub to mount the wheel to vehicle.
•It is located between the brake rotors and axle.

9. Design Consideration
•Thebolt patternis determined by the number
ofboltson the wheel hub.
•Selection of material strong enough to take the
weight of the car. weight of the car.
•Wheel bearings in the hub depending on ID
and OD of spindle coming out of hub.
•Type of lug nuts or bolts.

10. LITERATURE
REVIEW REVIEW

11. DESIGN CRITERIA AND DURABILITY
APPROVAL OF WHEEL HUB
SAE international,USA             11-16-1998        technical paper
authors : Gerhard fischer, VatroslovV. grubisic
Theauthorsaysthatthedesignof wheelhubmustbebasedon
stress generated under customer usage through operational
loads acting on wheels. Wheel hub are highly steered safety
components
which
must
not
fail
under
the
applied
loading
components
which
must
not
fail
under
the
applied
loading
conditions.
The main parameters for design of wheel hub
assembly are loading conditions , manufacturing process and
material behavior. The influence of these parameters are
interactive so material fatigue behaviour will be changed
dependinguponthewheelhubdesignandloadingconditions.

12. FRACTURE ANALYSIS OF WHEEL HUB
FABRICATED FROM PRESSURE DIE
ALUMINIUM ASSEMBLY
theoretical and applied fracture mechanics ,vol 9   feb1988
authors : S . Dhar
The author says that a catastrophic failure of wheel hub occu rred
during service. The nature of crack was a corner crack. An
analytical investigation was carried out using tool of line ar elastic
fracture
mechanics
to
establish
the
cause
of
failure
.
The
non
–
linear
fracture
mechanics
to
establish
the
cause
of
failure
.
The
non
–
linear
behavior is due to the presence of material inhomogeneties a nd
discontinuities.
An analytical estimation was carried out in order to
calculatetheminimumno.ofcyclescarriedbywheelhubinservice.
The initiation of crack growth is complex because the hetero geneity
and morphology of fracture surface. Fractographic and
metallographic studies are carried out to assist the unders tanding of
cornercrackingproblem.

13. Finite element modeling of dynamic impact and
cornering fatigue of cast aluminum and forged
magnesium road wheels.
Proquest dissertation and thesis                    2006
authors : Shang, Shixian (Robert)
The author says that numerical investigation of wheel dynam ics impact and
cornering fatigue performance is essential to shorten desi gn time , enhance
mechanism performance and lower development costs. The desertion
focused
on
two
objectives
:
focused
on
two
objectives
:
i) Finite element models of a dynamic impact test on wheel and tire
assembly were developed which considered the material in ho mogeneity
of wheels. Comparison of numerical predictions with experimental
measurements of wheel impact indicated 20% reduction of ini tial striker
kineticenergyprovideaneffective methodforsimplifying modeling.
ii)numericalpredictionofwheelcorneringfatiguetestin gwasconsidered.
It proceeded in two methods, first was static stress analysi s with bending
direction applied to the hub. Second was dynamic stress anal ysis with
applicationofa rotatingbendingmomentappliedtohub.

14. PRELIMINARY PRELIMINARY
PRODUCT DESIGN

15. Prototype CAD Model
Half Shaft
Isometric View

16. Parameters for Halfshaft
•L – Length of shaft
•D
o– Outer diameter of shaft
•D
i– Internal diameter of shaft
•
T
–
Maximum Torque applied by
•
T
–
Maximum Torque applied by differential on shaft
•σ – Maximum Normal Stress on shaft
•τ – Maximum Sheer Stress on shaft
•J – Polar Moment of Inertia of shaft
•G – Modulus of Rigidity

17. Wheel Hub

18. Parameters of Wheel Hub
•n Number of Bolts
•b Bolt Circle Diameter or
Pitch Circle Diameter
•
d

Flange diameter is measured
•
d

Flange diameter is measured between opposite holes
•S Spoke hole diameter
•W Width centre to flange
•P Load capacity is the amount of
weight a wheel will carry

19. THEORETICAL
DESIGN DESIGN

20. Ol1d 8Sxld-
GIVEN :
•rlWp.U. A9cFUg 9d gumpug l- 4BYYY cq. G 5=Y N8.
•Gear ratio for 1st gear = 1.833
•Final Drive ratio = 2.15
Material selection: Material selection: •The material chosen for the design of Half – shaft is ion nitrided t itanium
alloy.
•The titanium and titanium alloys have unique corrosion, nonmagnetic and
b-cgum-x T -98"gpmx- cl-p9 qc9qgc-pgbf
•Mechanical properties of nitride titanium alloys are as foll ows:
Yield stress =         1.24105631 × 10
9
Pascal
Maximum Sheer Stress =         0.62052815 × 10
9
Pascal

21. Calculation of Torque at halfshafts:
Shock torque = factor of safety x first gear ratio x final drive x maximum engine torque
= 2.5 x 1.833 x 2.15 x 280
= 2758.665 Nm.
Internal to external diameter ratio, k = 5
As T = 6246.765 Nm , τ = 0.62052815 × 10
9
Pascal , k = 5
The Axial Force acting upon the half

shafts has been countered by adding plunge to the
The Axial Force acting upon the half

shafts has been countered by adding plunge to the
C.V. joints at the end of the halfshafts
The Gyroscopic couple acting due to rotational masses likes tyr es, camshafts and
crankshafts is negligible as the rims, camshafts and crankshafts are made of light weight
titanium alloys which contribute insignificantly to gyroscopic coup le.
No bending moment is observed as no additional weight, except selfwe ight of half
shafts, is loaded on the halfshafts. Thus our calculations would be b ased upon the
strength required from shaft under torsional loading only.

22. T = (π/16) x τ x (d
o
)
3
x [ 1 –(d
i
/ d
o
)
4
]
We have, k = d
i
/ d
o
= 5
So, 2758.665 = (3.14/16) x 0.62x 10
9
x (d
o
)
3
[ 1 –(1/5)
4
]
d
o
3
= 22882.115
d
= 28.39 mm
d
o
= 28.39 mm
Or, d
o
= 29 mm.
Therefore, d
i
= 29/5
d
i
= 5.66 mm.
From the design calculation we find that the requir ed external and internal
diameter of the half –shaft as per the specified en gine parameters and given
conditions is 29 mm and 5.6 mm.

23. WheelHub Assembly
Tires and rims selection:
The tires selected were of 13” diameter. The diamet er was selected as
such that floor of the formula car does not touch t he ground. At the same
time a low ride height would give an aerodynamic as well as low Center
ofgravity advantage.
Number of bolts is taken 4 as it is a standard for 13” wheels.
Pitch Circle Diameter(P.C.D.) is fixed at 100 mm as it is a standard for
13” wheels.
Spoke Hole Diameter(S) is taken as M12 as it is a s tandard for 13”
wheels.
Material : Ti6Al4V titanium alloy is the most wide ly used .

24. Brake Force Calculation
•Brake force is required to estimate the load on the
wheel hub.
•
As almost all the design parameters of a wheel
•
As almost all the design parameters of a wheel hub are fixed by the size of wheel, the thickness
of the wheel hub is the defining parameter.
•The thickness of wheel hub is determined by
maximum force acting on a wheel.

25. Brake Calculation   :-
Velocity of Vehicle = v
o
Frictional force will be acting on it = F
Stopping distance = d
Friction force of the road must do enough work on the car to reduce its kine tic
energy to zero .
To reduce the kinetic energy to zero To reduce the kinetic energy to zero Workfriction = µmgd = 0.5mv
0
2
d= v
o
2
/2µg
Velocity of our vehicle = 150 km/hr
Friction of road = 0.90
d = 98.31 m

26. Acceleration of the vehicle:-
v
o
2
= u
2
+ 2ad
Where a is the acceleration of the vehicle
a = v
o
2
/2d
a = 8.8m/s
Total force acting on the vehicle
F
=
m
* a
F
total
=
m
v
* a
Where m
vis the mass of the vehicle = 640kg
F
total= 640 * 8.8 = 5632N
R9c,g 9u gl,x "xgg1s8
F
1= F
total/4 = 3953.43/4 =1408 N
F
1= 1408 N

27. Torque on the tire:-
T
r= F
1* r
tire
Rim is taken to be 13”
r
tire= 20.43 * 0.0254/2 = 0.2595 m
T
rG 4BY= P Yf5HMH G  73Hf7H N8.
Torque on disc:-
T
=
F
*
r
T
disc
=
F
friction
*
r
effective
disc is assumed to be 200mm , therefore r
effectiveshould be 9cm
we know that T
disc= T
tire
F
friction= 25647.012 / 9
F
friction= 2849.67N
R9c,g 9u -xg ,1l.qs8
F
clamp= F
friction/µ = 2849.67/0.5 = 5699.34 N

28. SOFTWARE SOFTWARE ANALYSIS

29. Wheel Hub Assembly
•In design stage, we estimated all the forces acting on hub and disc
•The wheel hub was modeled in CAD with given parameters
•The forces were applied on model using Finite Element Analysis in
..
COSMOS
..
COSMOS
•The thickness of hub was varied in increments of 2 mm till a Factor ..
of Safety value of 2 was attained
•Thus the final design of wheel hub is complete

30. Finite Element Analysis
No external forceExternal force applied
Factor of Safety =
2
Factor of Safety =
2

31. Safe Design

32. DETAILED PRODUCT
DESIGN DESIGN

33. Half Shaft
Material = ion nitride titanium alloy
Yield stress = 1.241 x 10
9
Pascal
Max. Shear stress = 0.62 x 10
9
Pascal
Engine characteristics
N = 1400 rpm
T = 280 N

m.
T = 280 N

m.
First gear ratio = 2.833
Final drive ratio = 2.15
Shock torque = 2758.665 Nm.
K, d
0/di = 5
External dia. = 29 mm.
Internal dia. = 5.6 mm

34. Wheel hub
Tyre dia. = 13”
No. of bolts = 4
Pitch circle dia. = 100mm.
Spoke hole dia. = M12
Material = Ti6Al4V –titanium allo y
Stopping distance = 98.31 m.
Velocity of vehicle = 150 Km/hr.
Acceleration of vehicle = 8.8 m/s
2.
Force on each wheel = 1408 N.
Torque on tyre(R13) = 388.75 Nm.
Diameter of disc = 200 mm.
Effective radius = 90 mm.
Clamping force = 8638.86 N.
Width of flange = 10 mm.

35. conclusion
•Wheel Hub has been designed for a formula 1 car of mass about 640 kg,
maximum speed of 300 km/hr and average speed of 150 km/hr.
•The designed assembly gives stability during rotati on of the wheels.
•The weight and dimension of the hub is such that it reduces the rotational
mass. mass.
•The design project enabled us to understand the var ious forces that act on a
half –shaft and wheel hub, while the Formula 1 race car is in running
condition.
•The calculated parameters help us to design half s haft and wheel hub
such.
•The design project helped to better under the uses of software in real
scenario.

36. GANTT CHART(Design Project)
"DESIGN OF HALF - SHAFT OF A PROTOTYPE RACE CAR"
Sl 
No. CATEGORY
Time in Weeks
1 2 3 4 5 6 7 8 9 10 11 12
A
Topic and guide selection 
for project
B Literature review 
C
Develop preliminary 
product design
D
Theoretical Design
D
Theoretical Design
E CAD modelling
F Software analysis
G Optimization of design
H
Develop detailed product 
design
I
Final Presentation 
Compilation
***Please note that the weeks mentioned above doesn ot contain the CAT weeks.

37. THANK YOU