Model development and the shape optimization analysis of a rear knuckle for race car

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 12 | Dec-2014, Available @ http://www.ijret.org 172
MODEL DEVELOPMENT AND THE SHAPE OPTIMIZATION
ANALYSIS OF A REAR KNUCKLE FOR RACE CAR
Yusop, M.S.M1
, Lazim, M.S.M2
, Razak, I.H.A3
, Hashim, M.F4
1
Universiti Kuala Lumpur, Malaysia France Institute, Seksyen 14, Jalan Teras Jernang, 43650 Bandar Baru Bangi,
Selangor, Malaysia
2
Selangor, Malaysia
3
Selangor, Malaysia
4
Institut Kemahiran Belia Negara Dusun Tua Batu 16, Dusun Tua, 43100 Hulu Langat, Selangor.Malaysia
Abstract
Automotive motorsport sector demands lightweight car component that directly contributes to fuel efficiency of a race car.
Currently, EIMA Race Car got issues with the car weight. The current knuckle is heavy and did not undergo design process and
analysis. The race cars need to compete with others in a 15 laps of endurance race. Refueling is prohibited during the race, thus it
is very important to ensure the parts are in top condition and lightweight. By using the selected method and optimization tool for
the rear knuckle, this paper looks into the design and development of a knuckle for EIMA race car. Solidworks has been used as a
design tool and analysis process. The final design then undergoes an optimization process and the proposed design has been
fabricated. The result can be considered successful as the new design is 70% lighter than the current rear knuckle.
Keywords: Product Design, simulation, race car knuckle, lightweight, optimization.
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1. INTRODUCTION
Educational Innovation of Motorsports & Automotive Race
(EIMARace) is an inter-institutional program that opens to
International and Public Higher Education Institute, Private
Higher Education Institute, College, Polytechnics, &
Technical Institutions that highlight education through
motorsports. EIMARace is a platform for students to apply
the theory they learnt and improve their skills in the
automotive sector indirectly. Participating in this
competition, students will fabricate a functional prototype of
a race car. The race car will be customized to suit the rules
and regulation of the competition. Each of parts and
components must be strong and lightweight to ensure the
race car to compete in the endurance race.
This research focuses on design and development of a rear
wheel knuckle for the race car. Knuckle is one of the
important parts which contains the wheel hub or spindle,
and attaches to the suspension components. It is variously
called a steering knuckle, or hub. The wheel and tire
assembly attach to the hub or spindle of the knuckle where
the tire/wheel rotates while being held in a stable plane of
motion by the knuckle and mounted securely onto the race
car chassis [1].
A race car required lightweight and sturdy components to
move fast [7]. A proper material selection will much
improve the strength of the rear knuckle and the
combination of lightweight materials for part will ensure the
total weight of the race car can be reduced. Thus, the
combination contributes the fuel efficiency to the optimal
usage [2].
Optimization is a process to simplify a design to reduce the
weight, manufacturing cost without reducing the initial
strength of a part [3]. There are four disciplines of
optimization process which are topology, shape, size and
topography optimization. In the research, shape and size
optimization was used to obtain the final optimum fillets,
outer dimensions and thickness of the rear knuckle design
[4].
The objective of the research is to study and investigate the
current rear knuckle for the race car and to design a new rear
knuckle that is light, sturdy using the optimization process.
2. METHODOLOGY
A series of study on the current knuckle has been done in
the early stage of the research. Interview with the experts
has been conducted to collect the important data. The
expertise is from the different positions and work related in
the race car team. Table 1 shows the experts information and
details.
Table 1: Experts information
Interviewees Gender Position Years of
Experience
Expert A Male Designer 3
Expert B Male Race Team
Manager
3
Expert C Male Engineer 5

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The data and information gathered from the expertise were
used as a main reference during the design and analysis.
Solidworks was used as a design and analysis tool. The
current rear knuckle was modeled and Finite element
analysis (FEA) was carried out to evaluate the performance
of the design. The analyzed data was set as a benchmark for
the minimum requirements for the new rear knuckle design.
Four (4) types of new rear knuckle design were modeled and
analyzed to meet the requirements for the race car. Series of
design validation has been done to choose the best design
for the rear knuckle. The chosen design undergoes an
optimization process to get the optimum shape and material
usage. Solidthinking by Hyperwork was used to optimize
the design. The optimized design was then remodeled in the
Solidworks to get the accurate shape and dimension. Figure
1 shows the flow chart of the design process.
Fig.1: Design Methodology flowchart
3. CONCEPTUAL DESIGN
There are four (4) types of rear knuckle design has been
modeled in the design tool. The concept design ideas and
requirements were based on the parameters given by the
Eimarace team. There are four (4) main parameters needs to
be considered during the design process.
The first parameter is lightweight. Lightweight ensure the
race car can accelerate and move faster. A lightweight
design contributes to the fuel efficiency of the race car.
Second parameter is the serviceability aspect. Technical race
team requires an easy method to dismantle for servicing the
parts and ergonomics was used for the new design. Third,
the new design was checked parallel with a series of
analysis simulation to improve the handle ability, response
and stability for the new design. The new design need to be
fabricated as easy as possible without secondary machining
process that could affect the strength of the new design.
Design tolerance [5] is also one of the important
considerations as the rear knuckle is an assembled part
where good alignment mates between parts are critical.
Fig 2: Rear Knuckle Design Parameters
Fig 3 below shows all four (4) designs based on the design
parameters in Fig 2. These designs have been analyzed
based on manufacturability, assembly and serviceability of
the part. Each design was briefly discussed with the experts
and results of the discussion were organized in Table 2. The
table shows the summarized advantages and disadvantages
of each rear knuckle designs.
Design 1

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Design 2
Design 3
Design 4
Fig 3: Four (4) new rear knuckle design
Table 2: Advantages & disadvantages of rear knuckle
design
Design Advantage Disadvantage
Design 1 Easy to fabricate, no
complex shape.
Difficult to assemble
the lower arm (the
space to insert lower
arm is smaller. Need
to consider the
diameter of race car
rims)
Design 2 Easy to assemble the
lower arm. The
upper arm has been
enlarged.
The design is bigger.
Design 3 Easy to assemble all
parts.
Difficult to fabricate
because the radius.
The design has more
edges.
Design 4 Easy to fabricate
because have no big
radius.
Easier to assemble
because the arm is
on the side of the
knuckle.
Longer machining
process because the
edges in the design.
Design 4 Easy to fabricate
because have no big
radius.
Easier to assemble
because the arm is
on the side of the
knuckle.
Longer machining
process because the
edges in the design.
4. MATERIAL SELECTION
The current knuckle is made by mild steel. Mild steel offers
good strength but it contributes more weight to the race car.
The mild steel was substituted with Aluminum 6061 T6.
This material offers a better strength and lightweight for the
race car. Due to the low weight of the material [6], fuel
consumption can be stretch to the optimum level. As per
discussion with the experts, aluminum 6061 T6 was chosen
due to the availability in Malaysian market and easy to
machine. Table 3 below shows the mechanical properties of
Aluminum 6061 T6.
Table 3: Material properties
Properties Value(Mpa)
Elastic Modulus 69000
Sheer Modulus 26000
Yield Strength 275
5. FEA ANALYSIS
A series of FEA analysis was done to the four (4) knuckle
design. The required load on the rear knuckle was
determined from various past researches. According to [7],
average weight of a passenger car is 400kg. The weight is

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distributed among all four knuckles. Eimarace car average
weight is 250kg. Thus,
=250kg/4 = 62.5kg, for each of the knuckle
W=mg
= 62.5 x 10 = 625N
Stress analysis was done on all four model shows in Figure
4. Initially, the fixture is fixed at the circle of the design, and
then the force was applied on the model. The value of the
load applied at the top and bottom is 312.5N each. The
displacement analysis were the analyzed on all model and
the overall result was tabulate in table 4 for further analysis
and to determine the best design for the Eimarace car.
Fig 4: Stress analysis result
Table 4: Analysis Result
Design
1
Design
2
Design
3
Design
4
Stress
analysis
results (Mpa)
210.3 381.4 379.6 210
Displacement
results (mm)
0.076 0.284 0.123 0.035
Mass (kg) 1.7 1.9 1.5 1.5
6. OPTIMIZATION
There are many optimization method offers to optimized a
design. Shape optimization [2] is one of the methods to
discover the optimal shape based on the model given in the
software.
Design 4 was chosen for optimization process. The same
analysis and load were applied in the optimization, and the
software will automatically calculate and recommend the
best optimal design for the rear knuckle. Figure 5 shows the
optimization process in the Solidthinking software.

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Fig 5: Optimization process
The optimized design was redrawn and reanalyzed again in
the Solidworks software to get the actual dimension, shape
and the analysis result. The result in table 5 shows improved
figure after the optimization process. Figure 6 shows the
final rear knuckle design.
Fig 6: Optimized rear knuckle design
Table 5: Optimized design analysis result
New Design 4
Stress analysis results
(Mpa)
120.3
Displacement results
(mm)
0.00027
Mass (kg) 0.9
7. CONCLUSION
The optimized rear knuckle design has been modeled and
analyzed using Solidworks and SolidThinking software. The
research shows the mass of the optimized design reduce by
52.6%. The maximum stress and displacement are also
improving even so the decreasing of the mass did not affect
the stiffness of the structure. Therefore, the overall weight
has been reduced to achieve the objectives of the race as
well as improve the fuel consumption to the optimum usage.
ACKNOWLEDGEMENTS
Yusop M. S. M. thanks IKBN Dusun Tua, Selangor and
Universiti Kuala Lumpur, Malaysia France Institute, to give
this opportunity and the Final Year Project students for this
research work.
REFERENCES
[1]. M. L. Syazwan, “Design and Development of Rear
Knuckle for a Race Car”. Final Year Project Report ,
January 2014
[2]. V.R. Kulkarni, A.G Tambe, “Optimization and Finite
Element Analysis of Steering Knuckle”, Altair Technology
Conference,2013
[3]. W.M. Wan Muhamad, E. Sujatmika, Hisham Hamid, F.
Tarlochan, “Modeling, Simulation and Optimization
Analysis on Steering Knuckle Component for Purpose of
Weight Reduction” , 2012
[4]. Y. Kojima, “Mechanical CAE in Automotive Design”.
R&D review of Toyota CRLD, Vol. 35, No.4, 2000.
[5]. E. Gabriela, R. Carles, L. Joaquim, “An Approach to
Avoid Quality Assembly Issues Since Product Design
Stage”. International Conference on Engineering Design,
2007
[6]. M.P. Sharma, D. S. Mevawala, H. Joshi, D. A. Patel,
“Static Analysis of Steering Knuckle and Its Optimization”.
IOSR Journal of Mechanical and Civil Engineering, 2014,
p.p 34-38
[7]. B. Babu, M. Prabhu, P. Dharmaraj, R. Sampath, “Stress
Analysis on Steering Knuckle of the Automobile Steering
System”. International Journal of Research in Engineering
and Technology, 2014
BIOGRAPHIES
Yusop, M.S.M. is currently a lecturer in the
Mechanical and Manufacturing Section at
Universiti Kuala Lumpur Malaysia France
Institute. His research interests include
product design, mould technology and
manufacturing.
E-mail:mshahrilmy@unikl.edu.my
Lazim, M.S.M. graduated with a Bachelor of
Engineering Technology in Machine Tools
Manufacturing at Universiti Kuala Lumpur
Malaysia France Institute. His research
interests include product design and
simulation.
E-mail: mohd_syazwann@yahoo.com
Razak, I.H.A. is currently a lecturer in the
Mechanical and Manufacturing Section at
Universiti Kuala Lumpur Malaysia France
Institute. Her research interests include
manufacturing system and design.
E-mail: izatulhamimi@unikl.edu. my

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Hashim, M.F. is currently a lecturer in the
Mechanical Department at Institut
Kemahiran Belia Negara, Dusun Tua. His
research interests include product design,
automotive and manufacturing.
E-mail: faisoul@kbs.gov. my

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Model development and the shape optimization analysis of a rear knuckle for race car