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ISSN 2348-7852 (Print) | ISSN 2348-7860 (Online) ijre.org
IJRE | Vol. 03 No. 04 | April 2016
DESIGN AND ANALYSIS OF CHASSIS FRAME Author(s):
1Anurag,
1Amrendra Kumar Singh,
1Akash Tripathi,
1Aditya Pratap Tiwari,
1Nitish upadhyay,
2Shyam Bihari Lal
Student1,Asst. Prof.
2, Dept. of Mechanical Engineering, Buddha Institute of Technology, Gorakhpur, U.P. India
Abstract– Truck chassis is the structural backbone of any
vehicle. The main function of the truck chassis is to carry
the goods and payload placed upon it. The chassis frame
has to bear the stresses developed and deformation occurs
in it and that should be within a limit. This paper presents
the study of the stress developed in chassis as well as
deformation of chassis frame. The stress and deformation
has been calculated for the chassis frame and the analysis
has been done for the validation on the chassis frame. The
model of the chassis has been developed in Creo (Pro-E)
2.0 and static structural analysis has been done in ANSYS
WORKBENCH 15.0.
Keywords:Truck Chassis, Static Structural Analysis, ANSYS
WORKBENCH 15.0,Deformation,Ladder Frame.
I.INTRODUCTION
Automobile chassis usually refers to the lower part of
the vehicle including the tires, engine, frame, driveline and
suspension. Out of these, the frame gives necessary support to
the vehicle components placed on it. Also the frame should be
so strong to resist impact load, twist, vibrations and other
bending stresses. The chassis frame consists of side rails
attached with a number of cross members.
Along with the strength, an important consideration
in the chassis design is to increase the bending stiffness and
torsion stiffness. Proper torsional stiffness is required to have
good handling characteristics. Commonly the chassis are
designed on the basis of strength and stiffness. In the
conventional design procedure the design is based on the
strength and is then focused to increase the stiffness of the
chassis, with very small consideration to the weight of the
chassis. This design procedure involves the adding of
structural cross member to the existing chassis to improve its
torsional stiffness. As a result, weight of the chassis increases.
This increase in weight of the chassis fuel efficiency is
reduced and increases the overall cost due to extra material.
The design of the chassis with proper stiffness and strength is
necessary.
The design of a vehicle structure is of fundamental
importance to the overall vehicle performance. The vehicle
structure plays an important role in the reliability of the
vehicle. Generally, truck is a heavy motor vehicle which is
designed for carrying the attached weights, such as the engine,
transmission and suspension as well as the passengers and
payload. The major focus in the truck manufacturing industries
is to design vehicles with more payload capacity. Using high
strength steels than the conventional ones are possible with
corresponding increase in payload capacity.
The chassis of truck which is the main part of the
vehicle that combines the main truck component systems such
as the axles, suspension, power train, cab and trailer etc.,
asshown in Figure-1, is one of the possible candidates for
substantial weight reduction.
Automotive designers need to have complete
understanding of various stresses prevalent in different areas
of the chassis component. During the conceptual design stage,
when changes to the design is easy to implement and have less
impact on overall project cost, the weight and structural
characteristics are mostly unknown since detailed and overall
vehicle information is not available at the early stage .
The vehicle design starts up with conceptual studies
to define size, number and location of undriven and drive
axles, type of suspension, engine power, transmission, tire size
and axle reduction ratio, cab size and auxiliary equipment. The
selected configuration has to be more precise and accurate for
the considered transportation tasks and should match the
existing production line. In general, there are two approaches
to analyze truck chassis: one is stress analysis to predict the
weak points and the other is fatigue analysis to predict life
cycle of the frame.
This overview selectively and briefly discusses some
of the recent and current developments of the stress analysis of
truck chassis. A number of analytical, numerical and
experimental methods are kept in mind for the stress analysis
of the heavy duty truck frames. Conclusion of the stress
analysis in the vehicle chassis has been reported in literature.
Finally, the scope of future work has been discussed after
concluding on the obtained results.
Figure-1 3D Modelling of Chassis Frame
Side Member
Cross Member
Connecting
Plate
Rivet
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ISSN 2348-7852 (Print) | ISSN 2348-7860 (Online) ijre.org
IJRE | Vol. 03 No. 04 | April 2016
II. METHODOLOGY
This study has been dealt with two parts. First part of this
study involves modeling of chassis frame and analysis of
stresses and displacement under actual load conditions. CAD
models of chassis frame were developed in 3D modeling
software, such as Creo (Pro-E) 2.0 (Pro-E). The stress analysis
and stiffness of the models are then obtained in ANSYS
WORKBENCH 15.0. While the second part is shape
optimization as weight or mass reduction purpose utilizing
solid. Weight of the proposed design of chassis frame is then
being compared to the current component that have been used
for the previous existing chassis model [4].
Approach of this study is shown in Fig - 2.
Figure-2 Design Methodology Flowchart
III. MODELING OF EXISTING CHASSIS FRAME
The model of chassis which has been used currently
as per the dimension is created in Creo (Pro-E) 2.0 as shown
in Figure 3.The model is then saved in IGES format which
can be directly imported into ANSYS WORKBENCH 15.0 .
Figure 3 shows the imported model in ANSYS
WORKBENCH 15.0.
Figure-3 Actual C-beams chassis
IV. DESIGN OF CHASSIS FRAME
(A) Calculation of Load
i) Axial Loads
There are two axial load acting on the chassis frame such as
tensile load and compressive load [5]. The stress due to this
load can be find out using the following formulae,
Tensile Load (Pt) = Tensile stress x Area
Compressive Load (Pc) = Compressive stress x Area
ii) Bending Load
This load acts on the chassis frame due to the weight of the
vehicle and this tends to bend the chassis frame downward
away from the centerline [5]. Total inertia bending load is
given by,
Bending Load (Fb) = 𝝆𝑨𝒕𝑳 𝒔𝒊𝒏(𝜽+∅)
𝟐 N
(B) Calculation of Stresses
i) Stress Due to Axial Loads
The force of resistance per unit area, offered by a body
against deformation is known as stress.
This is given by,
Stress (σ) = 𝑷
𝑨
ii) Stress due to Inertia bending force
Inertia bending load sets up a stress which would be tensile on
one side of the chassis and compressive on another side and
that these stress change sign each half revolution [5].The
bending moment at any section „x‟ m from the small end is
given by,
M = 𝑥
𝑎 1 −
𝑥2
𝐿2
The stress is calculated by,
σb =𝑀
𝑍
Initiates and evaluate current design
Redraw and analyze current design
Design Modeling
Creo (Pro-e),
FEA Analysis
ANSYS WORKBENCH
Evaluat
e
Design
Further analysis and optimization
Further Evaluate Design or Optimized Design
Final Design and stop
yes
no
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IJRE | Vol. 03 No. 04 | April 2016
V. MESHED MODEL OF CHASSIS
Meshing of the chassis frame model is done in ANSYS
WORKBENCH 15.0. The meshed model is shown in fig. 4
Figure-4Zoomed View of Meshed model of Chassis frame
NUMBER OF NODES 301873
NUMBER OF ELEMENTS 141884
Table-1 Nodes and Elements of Model
V. MATERIAL OF MODEL
For the frame geometry of chassis commonly steel
and its alloys are used. For the frame models, variety of
materials, composite materials and different kind of alloys
like steel, Carbon/Epoxy, E-Glass/Epoxy, S-Glass/Epoxy, etc.
can be used. In the present study HSLA Steel is used and its
properties are as given below.
Material HSLA Steel
Modulus of Elasticity E 2.6 x 105N/mm
2
Poisson’s Ratio 0.3
Tensile Yield Strength 310 Mpa
Tensile Ultimate Strength 448 Mpa
Density 7800 kg/m3
Thermal Conductivity 43w/m-k
Table-2 Material properties of chassis
CHEMICAL COMPOSITION
Quantity %Weight (max)
Carbon 0.16
Silicon 0.15-0.35
Manganese 0.8-1.3
Phosphorous 0.025
Sulphur 0.025
Niobium 0.02-0.05
Table-3 Chemical Composition of HSLA Steel
VI. ANALYSIS
(A) LOADS IN A STATIC ANALYSIS
Static analysis is used to determine the force in structure ,
displacement, stress, strain or component cause by load that do
not induced significant inertia and damping effect[5].
There are following type of load apply in static analysis
which are given below.
Externally applied forces.
Steady-state inertial forces.
Figure-5 Loading Condition of Chassis Frame
(B) STATIC ANALYSIS A static analysis calculate the effect of steady loading
condition on the structure, while ignoring inertia and damping
effect such as those caused by the varying load and time-
varying load can be approximated as static equivalent load[5].
Figure-6 Total deformation (HSLA Steel)
Figure-7 Von Mises stress (HSLA Steel)
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IJRE | Vol. 03 No. 04 | April 2016
Figure-8 Maximum Principal Stress (HSLA Steel)
Figure-9 Maximum Shear Stress (HSLA Steel)
(C) PROCEDURE FOR STATIC ANALYSIS
There are three main steps involve in static analysis.
i) Build the model
ii) Apply load and obtain solution
iii) Review the result
.
VII. RESULT
Previous model of the chassis frame which is made
up of steel (mild steel) having yield strength 250 Mpa and
mass is about 597.67 kg. We have selected HSLA Steel for
analysis having yield strength 310 Mpa and mass is about
593.87 kg. The percentage mass reduction of the chassis frame
was found to be 0.63%. The optimized value of the result is
given below.
Parameters Initial Material
(Mild Steel)
Final Material
(HSLA Steel)
Total Deformation 0.0088mm 0.0084mm
Maximum
Principal Stress
44140 Pa 44574 Pa
MASS
Initial Material
(Mild Steel)
Final Material
(HSLA Steel)
% Reduction
597.67 kg 593.87 kg 0.63%
Table-4Comparison of Chassis Frame
VII. CONCLUSION
The chassis frame component has been modelled
using Creo (Pro-E) 2.0 and analyzed in ANSYS
WORKBENCH 15.0. The various parameters such as Nodal
displacement, stress distribution are completely analyzed and
studied. The study shows that the area where the stress
concentration is maximum due to applied load and the portions
that has to be considered in the design of chassis frame in
order to avoid frequent failures to improve its reliability.
Stress analysis of chassis has been done to predict the
weak points. Several state of the art papers and even books on
chassis stress analysis have been presented in the recent
years.This study makes a case for further investigation on the
design of truck chassis using Ansys software.
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