This document presents a study on the structural analysis and optimization of an automotive chassis for the Eicher 11.10 model using ANSYS software, focusing on improving torsional stiffness and reducing weight. The analysis resulted in a maximum torsional stiffness of 6448 nm/deg, which is a 377% increase over the baseline model, while achieving significant increases in efficiency. The study emphasizes the importance of achieving a balance between strength, stiffness, and weight to enhance vehicle performance and safety.

1. CADmantra Technologies Pvt. Ltd.
All right reserved @ cadmantra technologies pvt. ltd.
STRUCTURAL ANALYSIS OF A CHASSIS OF
EICHER 11.10 USING “ANSYS”
Bhola Patel
Design Engineer
CADmantra Technologies Pvt. Ltd.
Contact: bholapatel.me@gmail.com
ABSTRACT : Automotive chassis is an important part of an automobile. The chassis serves as an frame work
for supporting the body and different parts of the automobile. Also, it should be rigid enough to withstand the
shock, twist, vibration and other stresses. Along with strength, an important consideration in chassis design is to
have adequate bending and torsional stiffness for better handling characteristics. So, strength and stiffness are
two important criteria for the design of the chassis. This report is the work performed towards the optimization
of the automotive chassis with constraints of stiffness, strength and natural frequency. The design improvement
study performed resulted in a maximum torsional stiffness of 6448Nm/deg, an increase of 377% over the
baseline model. A maximum increase in efficiency of 286% to 23g/Nm/deg for a mass of 148.3Kg accompanied
this increase in torsional stiffness. Following optimization of the model to gain minimum mass for a stiffness of
6000Nm/deg a torsional stiffness of 6030Nm/deg was realised for a mass of 127Kg, giving an increase in
efficiency of 322% over the baseline model to 20.99g/Nm/deg.
1. INTRODUCTION
Automobile chassis usually refers to the lower body
of the vehicle including the tires, engine, frame,
driveline and suspension. Out of these, the frame
provides necessary support to the vehicle components
placed on it. Also the frame should be strong enough
to withstand shock, twist, vibrations and other
stresses. The chassis frame consists of side members
attached with a series of cross members.
Along with the strength an important consideration in
the chassis design is to increase the stiffness (bending
and torsion) characteristics. Adequate torsional
stiffness is required to have good handling
characteristics. Normally the chassis are designed on
the basis of strength and stiffness. In the conventional
design procedure the design is based on the strength
and emphasis is then given to increase the stiffness of
the chassis, with very little consideration to the
weight of the chassis. One such design procedure
involves the adding of structural cross member to the
existing chassis to increase its torsional stiffness. As
a result weight of the chassis increases. This increase
in weight reduces the fuel efficiency and increases
the cost due to extra material. The design of the
chassis with adequate stiffness, strength and lower
weight provides the motivation for this project.
The goal of the structural design is to obtain
minimum component weight and satisfying
requirements of loads (stresses), stiffness, etc. The
process of producing a best structure having optimum
structural performance is termed as structural
optimization. Structural systems like the chassis can
be easily analyzed for the stress, and stiffness, etc.
using finite element techniques. The limitations on
the stress, strength etc. are the constraints for
optimization.
2. CASE STUDY
The four models in this study represent the same
bracket. It is rigidly supported at the back and loaded
with uniform pressure applied to the top of the
hollow cantilever. Each model produces different
results.
3. MODEL
It uses a first-order solid tetrahedral element which,
by design, can only model constant stress within its
volume. Knowing that, there are two big problems.
First, only one element is placed across the thickness
of the plate in bending. This model is not capable of
representing bending stress which changes from
compressive to tensile across the plate thickness.
Consequently, bending stresses are badly represented
by constant stress. The second problem is that the
elements are highly distorted. Each type of element
works well only if it is within specified shape limits.
If element distortion is beyond these limits, then
numerical procedures used to calculate displacements
and stresses return false results.
Figure 1. Results for Model show a maximum Von
Mises stress of 18,000 psi

2. CADmantra Technologies Pvt. Ltd.
All right reserved @ cadmantra technologies pvt. ltd.
LOADS ON THE FRAME
The frame experiences loads of different nature
during motion of the vehicle. These loads, in turn,
produce stresses and strains of various kinds.
Generally, the following types of loads are sustained
by the frame.
FLEXURAL (OR BENDING) LOAD
It is produced in a vertical plane of the side members
due to
 Dead weight of the vehicle
 Weight of the passengers
 Engine torque
 Braking torque
Flexure load also develops in lateral plane of the side
members due to
 road Camber
 cornering force
 side wind
CALCULATION FOR EICHER E211.10
CHASSIS
Model No. = 11.10 (Eicher E2)
Capacity of Eicher = 8 ton
Capacity of Eicher with 1.25% = 78480 N
Weight of the Eicher = 2 ton
Total Load acting on the Chassis = Capacity of the
Chassis + Weight of Eicher
Calculation of the Deflection for Individual Side
Bar
Mmax = 37526845 N-mm
76.20
203.20
h
b1
b
Moment of Inertia around the X – X axis:-
Ixx = {bh3
– [b1(h)3
]} / 12
= [(76.20 x 203.203
) – (66.67 x 184.143
)] / 12
=18588475.09 mm3
Section of Modules around the X – X axis:-
Zxx = {bh3
– [b1(h)3
]} / 6h
= [(76.20 x 203.203
) – (66.67 x 184.143
)] / (6 x
203.20) = 182957.432 mm3
Basic Bending equation are as follow :=(M / I) = (σ /
y) = (E / R)
Material of the “C” channel:-
Material : St 52
E = 2.10 x 105
N / mm2
Poisson Ratio = 0.28
Radius of Gyration R = (203.20 / 2)
=101.60 mm
Maximum Bending Moment acting on the Beam: -
Mmax = 37526845 N-mm
I = 18588475.09 mm4
Y = 101.60 mm
CALCULATION FOR TORSIONAL STRESS
GENERATED IN CHASSIS
Reaction generated on Beam at the center of wheel
alignment: - 29430 N
With the consideration of at the rate of angle of twist
= 1˚
θ = (1˚ x π / 180) = 0.017452
By considering the whole system as a one rotational
body as per following data when in twist from its
support.
Width of the chassis: - 800mm
Length of chassis; - 6900mm
Distance between two reaction: - 4900mm
Modulus of rigidity for structural steel: - 80000
N/mm2
Now basic rule for Twisting Moment is:-
(T / J) = (τ / r) = (G x θ / L)
Now equating
(T / J) = (G x θ / L)
For the rotational shaft J is 2 times higher the Mass
Moment of inertia:-
Mass moment of Inertia for Chassis body = 4.65 x
107
mm4
So, Polar Moment of Inertia J= 2 x I
J= 2 x 4.65 x 107
J= 9.3 x 107
T = (G x θ x J) / L
T = (80000 x 0.017452 x 9.3 x 107
) / 6900
T = 18817808.70 N-mm
Torsional stress generated in Chassis body :-
Take width of body as a radius o rotational body r =
800mm
(T / J) = (τ / r)
τ = (T x r) / J
τ = (18817808.70 x 800) / 9.3 x 107
τ = 161.87 N/mm2
4. CONCLUSION
At present time the problem of enhancing safety is
very actual for the world automotive industry and
chassis is the backbone of the automotive system.
Day by day modification has been done in existing
system to increase strength and durability with
minimum possible cost. Here is the one approach
presented.
This project represent to study the stress-distribution
of automobile chassis. When different parts are
mounted o n it at that time no. of stresses are produce
in chassis. First Design stress is calculated then it was
compare with the stress result of Finite element
Analysis report by using pro-Mechanica tool. Its
9.53

3. CADmantra Technologies Pvt. Ltd.
All right reserved @ cadmantra technologies pvt. ltd.
comes within the limit So we can say that design is
safe.
5. REFERENCES
[1] Automobile Engineering – Vol.1 -
K.M.Gupta , Umesh Publication – 2001, page no. 54
to 61
[2] Automobile Mechanics , Dr. N. K. Giri,
Khanna Publisher, Delhi-2003, page no. 161 to 164
[3] Technical manual of Eicher E2 11.10,
Apco motors pvt. Ltd., Himmatnagar. Eicher motors
sells & service center.
[4] www.eicherworld.com
[5] Automobile Engineering, Vol.-I by Kirpal
sing, Standard Publisher and Distributor, Delhi-2003.
[6] Optimization of frameworks by means of
FEM use, By J. GADUŠ, Slovak Agricultural
University, Nitra, Slovak Republic, RES. AGR.
ENG., 49, 2003 (1): 32–36
[7] Analysis of Torsional Stiffness and design
improvement study of a Kit Car Chassis Prototype,
by Wesley Linton, M.Sc. THESIS, CRANFIELD
UNIVERSITY,SCHOOL OF INDUSTRIAL AND
MANUFACTURING SCIENCE MOTORSPORT
ENGINEERING AND MANAGEMENT 2001-2
[8] M.Tech. Dissertation “Structural
Optimization of Automotive Chassis” By Roopesh
Shroff, Department of Mechanical Engg. , IIT
,Bombay -Academic year 2002
[9] “Finite element analysis” by – Chandra
Patla.
[10] “Finite element analysis” by – Robert D.
cook