Stress analysis on steering knuckle of the automobile steering system

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 03 Issue: 03 | Mar-2014, Available @ http://www.ijret.org 363
STRESS ANALYSIS ON STEERING KNUCKLE OF THE AUTOMOBILE
STEERING SYSTEM
B.Babu1
, M. Prabhu2
, P.Dharmaraj3
, R.Sampath4
1
PG Scholar, Manufacturing Engineering, Karpagam University, Coimbatore, Tamilnadu, India
2
Assistant Professor, Mechanical Engineering, kathircollege of Engineering, Coimbatore, Tamilnadu, India
3
Assistant Professor, Mechanical Engineering, kathircollege of Engineering, Coimbatore, Tamilnadu, India
4
PG Scholar, Thermal Engineering, RVScollege of engineering and technology, Coimbatore, Tamilnadu, India
Abstract
Steering Knuckle plays major role in many direction control of the vehicle it is also linked with other linkages and supports the
vertical weight of the car. Therefore, it requires high precision, quality, and durability. The main objective of this work is to explore
performance opportunities, in the design and production of a steering knuckle. This can be achieved by performing a detailed load
analysis. Therefore, this study has been dealt with two steps. First part of the study involves modeling of the steering knuckle with the
design parameters using the latest modeling software, and also it includes the determination of loads acting on the steering knuckle as
a function of time. This is done for finding out the minimum stress area. Then the stress analysis was performed using analysis
software. The steering knuckle can be modeled, and analyzed under the actual load conditions. This may also improve the depth
knowledge of its function and performance in terms of durability and quality.
Keywords: Steering knuckle, stress analysis and Finite Element Analysis (FEA).
-----------------------------------------------------------------------***----------------------------------------------------------------------
1. INTRODUCTION
1.1 Introduction to Steering Knuckle
The steering knuckle is the connection between the tie rod,
stub axle and axle housing. Steering knuckle is connected to
the axle housing by using king pin. Another end is connected
to the tie rod. Then the wheel hub is fixed over the knuckle
using a bearing. The function of the steering knuckle is to
convert linear motion of the tie rod into angular motion of the
stub axle.
The lighter steering knuckle resulting greater power and less
the vibration because of the inertia is less. The steering
knuckle carries the power thrust from tie rod to the stub axle
and hence it must be very strong, rigid and also as light as
possible. In the case of automobile vehicle, during steering
and turning the steering knuckle is subjected to compressive
and tension loads and due to the wheel rotation it is also
subjected to torsional load.
Steering knuckle for automobile applications is typically
manufactured either by forging or from casting. However,
castings could have blow-holes which are detrimental from
durability and fatigue points of view. The fact that forgings
produce blow-hole-free and better parts gives them an
advantage over cast parts.
Due to its large volume production, it is only logical that
optimization of the steering knuckle for its weight or volume
will result in large-scale savings. It can also achieve the
objective of reducing the weight of the vehicle component,
thus reducing inertia loads, reducing vehicle weight and
improving vehicle performance and fuel economy.
Fig 1 Steering Knuckle with the Wheel Hub
1.2 Overall Objectives
1.2.1 Modeling of the Steering Knuckle
Modeling of the steering knuckles using a 3D modeling
software with its standard dimensions

__________________________________________________________________________________________
1.2.2 Analysis
Perform load analysis.
2. PROBLEM DEFINITION
As today’s automobile vehicle, required to have higher speed
and power, their steering knuckle have higher strength and
stiffness, but must be lighter in weight and size. In developing
power output vehicle, importance is placed on the weight of
the linier and angular parts steering arm, tie rod, pitman arm
etc. The overall performance of the steering system is affected
by higher inertia forces, generated by the moving parts of the
vehicle. Therefore, it should always be investigated to avoid
any failure of the vehicle in the long run.
The following are the main problems which are found in the
manufacturing of the knuckle:
i. Due to uneven stress distribution over steering knuckle, its
life reduces.
ii. This affects the overall performance of an automobile
vehicle.
iii. Due to the lack of knowledge of stress distribution the
material wastage may occur.
3. DESIGN METHODOLOGY
3.1 Analytical Evaluations
 Digitizing steering knuckle geometry
 Stress (FEA) Analysis
 Modal Analysis
Fig 2 Analysis Flow Chart
3.2 Steps Involved in Methodology
Step 1: Modeling of steering knuckle using 3D modeling
software.
Step 2: Finite element modeling of the steering knuckle.
Step 3: Analysis of steering knuckle using CATIA software.
i. Element selection.
ii. Discretization.
iii. Mesh generation.
Step 4: Finite element stress analysis.
Step 5: Modal analysis.
4. DESIGN OF STEERING KNUCKLE
4.1 Calculation of Load
4.1.1 Axial Loads
The two major loads acting on the knuckle are Tensile and
Compressive loads. The stresses due to these loads can be
determined using the following formulas
Tensile Load (Pt) = Tensile Stress X Area
Compressive Load (Pc) = Compressive Stress X Area
4.1.2 Inertia Load
This load is due to the inertia of the moving parts. To calculate
the inertia force, first two harmonies are taken into
consideration. It is given by,
Inertia load (Fa) =
4.1.3 Bending Load
This load is due to the weight of the vehicle which is acting on
the knuckle. This force trends to bend the steering knuckle
outwards, away from the centre line. It is alternating one, and
at high speed, it is considerable.
Total inertia bending force is given by
4.2 Calculation of Stresses
4.2.1 Stress due to Axial Loads
These stresses are calculated as follows,
4.2.2 Stress due to Inertia Bending Force
Inertia bending load sets up a stress which would be tensile on
one side of the knuckle and compressive on another side and
that these stresses change sign each half revolution. The

__________________________________________________________________________________________
bending moment at any section 'x' m from the small end is
given by
The stress is calculated by using the formula,
5. FINITE ELEMENT ANALYSIS OF THE
STEERING KNUCKLE
5.1 Analysis Procedure
5.1.1 Static Analysis
A static analysis calculates the effects of steady loading
conditions on a structure, while ignoring inertia and damping
effects such as those caused by time varying loads.A static
analysis can, however, include steady inertia loads such as
gravity and rotational velocity, and time – varying loads that
can be approximated as static equivalent loads.
5.1.2 LOADS IN A STATIC ANALYSIS
Static analysis is used to determine the displacements, stresses,
strains, and forces in structures or components caused by loads
that do not induce significant inertia and damping effects.
Steady loading and response conditions are assumed that is,
the loads and the structure’s response are assumed to vary
slowly with respect to time. The kinds of loading that can be
applied in a static analysis include:
Externally applied forces and pressures
Steady- state inertial forces (such as gravity and
rotational velocity)
Imposed (non-zero) displacements
Temperatures (for thermal strain)
5.2 Procedure for A Static Analysis
The procedure for a static analysis consists of three main
steps. The overall equilibrium equations for linear structural
static analysis are:
1. Build the model
2. Apply loads and obtain the solution
3. Review the results
[K] {u} = {F}
OR
[k] {u} = {Fq} N + {Fq}
4. Build the model:
To build the model, define the element types, element real
constants, material properties, and the model geometry.
5. Apply loads and obtain the solution:
In this step, the loads (boundary conditions) are defined and
the solution is obtained.
6. Review the results:
After the solution is completed, the post-processing step gives
the results of the static analysis.
Primary data available
Nodal displacements (UX, UY, UZ, ROTX, ROTY,
ROTZ)
Derived data available
Nodal and element stresses
Nodal and element strains
Element forces
Nodal reaction forces Etc.,
5.3 METHODOLOGY
Following are the process by which the analyzing processes of
steering knuckle is done.
Modeling using CATIA
Importing to CATIA Workbench
Generating Meshing
Applying material properties
Plotting the result
5.3.1 Modeling of the Steering Knuckle
The modelling is done using CATIA with the help of standard
dimensions that we got through the careful review. The Catia
is one of the famous modelling software available in the
market which enables us not only to do the modelling of the
components but also the analysis of the same. Hence it is one
of the ideal software for modelling and analysis problems. The
following diagram is the model of the steering knuckle which
is created using the Catia Software.
Fig 3 Model of the Steering Knuckle

__________________________________________________________________________________________
5.3.2 Meshing the Model
The process for generating a mesh of nodes and elements
consists of three general steps:
 CATIA offers a large number of mesh controls from
which you can choose as needs dictate.
 Set the element attributes.
 Set mesh controls (optional).
It is not always necessary to set mesh controls because the
default mesh controls are appropriate for many models. If no
controls are specified, the program will use the default settings
to produce a free mesh. Alternatively, you can use the Smart
Size feature to produce a better quality free mesh.
6. RESULTS
The results are plotted in the form of contour plot for stress
distribution as shown in the figure.
Fig 4 Von Mises Stress Value
7. CONCLUSIONS
The steering knuckle has been modeled and analyzed using
Catia. The various parameters such as Nodal displacements,
Stress distribution are completely analyzed and studied. This
study shows that the areas where the stress concentration is
maximum due to the applied load and the portions that has to
considered in the design of steering knuckle in order to avoid
frequent failures to improve its reliability.
REFERENCES
[1]. Athavale, S. and Sajanpawar, P. R., 1991, “Studies on
Some Modelling Aspects in the Finite Element Analysis of
Small Gasoline Engine Components,” Small Engine
Technology Conference Proceedings, Society of Automotive
Engineers of Japan, Tokyo, PP. 379-389.
[2]. Farzin h. Montazersadgh and Ali Fatemi, 2007, “Dynamic
Load and Stress Analysis of a Crankshaft”, SAE International.
[3]. A. Fuganti and G. Cupitò, 2000, “Thixoforming of
aluminium alloy for weight saving of a suspension steering
knuckle”Italy, 2000.
[4]. R. L. Jhala, K. D. Kothari and S.S. Khandare , 2009,
“Component Fatigue Behaviors And Life Predictions Of A
Steering Knuckle Using Finite Element Analysis” Proceedings
of the International MultiConferenceofEngineers.
[5]. Computer Scientists 2009 Vol II, IMECS 2009, March 18
- 20, 2009, Hong Kong.
[6]. Lee, S. B., “Structural Fatigue Tests of Automobile
Components under Constant Amplitude Loadings,” Fatigue
Life Analysis and Prediction, Proceedings, International
Conference and Exposition on Fatigue, Goel, V. S., Ed.,
American Society of Metals, 1986, pp. 177-186.
[7]. Rice, R. C., ed., 1997, “SAE Fatigue Design Handbook”,
Society of Automotive Engineers, Warrendale, 3rd Edition.
[8]. Savaidis, G., “Analysis of Fatigue Behavior of a Vehicle
Axle Steering Arm Based on Local Stresses and Strains,”
Material wissenschaft und Werkstoff technik, Vol. 32, No. 4,
2001, pp. 362, 368.
BIOGRAPHIES
B. Babu is currently pursuing M.E
programme from Karpagam University,
Coimbatore, India. He is currently
Assistant professor in Department of
mechanical engineering, KathirCollege of
engineering. He has published 06 papers
in International journals and 10 papers in
national/international conference.
e-mail-babuamr11@gmail.com
M.PRABHU is currently Assistant
professor in Department of mechanical
engineering, Kathir College of engineering.
He has published 04 papers in International
journals and 7 papers in
e-mail- prabhumechanical.m@gmail.com
P. Dharamaraj is currently Assistant
professor in Department of mechanical
engineering, Kathir College of
engineering. He has published 04 papers
e-mail- dharmarajmeap@gmail.com
R. Sampath is currently pursuing M.E
programme from Rvs college of
engineering and technology,
Coimbatore. He has published 02 papers
e-mail-arangasampath@gmail.com

Stress analysis on steering knuckle of the automobile steering system

More Related Content

What's hot (20)

Similar to Stress analysis on steering knuckle of the automobile steering system (20)

More from eSAT Journals (20)

Recently uploaded (20)

Stress analysis on steering knuckle of the automobile steering system