International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014
Design and Analysis of Army Vehicle Chassis
* Tandra Naveen kumar1
1PG
N.Jeevan Kumar 2
2 Associate
Student (M. Tech- CAD/CAM,
Professor,
Dept. of Mechanical Engineering,
Holy Mary Institute of Technology and Science, Jawaharlal Nehru technological University, Hyderabad,
India.
Abstract- In the current project manual design
calculations of the army vehicle chassis are
performed initially and the same design has
been validated using finite element analysis.
The following analysis was carried out to study
the structural integrity of the “Army vehicle
chassis” under various loading conditions.
Firstly a static analysis with only equipment
loads applied. Secondly static analysis in
deployment mode. (The vehicle is lifted from
ground with jacks. Loads on Army vehicle
chassis include equipment as well as bare
vehicle weight). Thirdly Modal analysis to find
the Natural Frequencies was carried out. From
the results obtained some changes were
proposed and implemented to reduce the
deflections and stresses and also efforts are
made to increase the fundamental natural
frequency of the chassis.
Keywords: Army vehicle Chasis, Deflections, Stress,
carrying Shelter mounted Electronic Equipment
and its accessories.
The Design of the Vehicle Army vehicle
chassis is carried so as to carry the below
mentioned items. The Army vehicle chassis
design is optimized to keep the weight of the
Army vehicle chassis to the minimum. Finite
Element Analysis is carried out for verification.
The Army vehicle chassis has provision to fix the
following major equipment.
Shelter: A Shelter will be fixed on to the
Army vehicle chassis with bottom four ISO
corners using four Twist locks provided on the
Army vehicle chassis.
Generators: One Generator is mounted on
Modal analysis.
the front portion of the Army vehicle chassis
(behind Driver’s Cabin).A frame covering the
1 INTRODUCTION
Chassis is a major component in a vehicle
system. For vehicles, chassis consists of an
assembly of all the essential parts of a vehicle
(without the body) to be ready for operation on
the road. This project deals with the design
optimization of the Army vehicle chassis for the
different loading conditions. Army vehicle chassis
is steel welded Structure of size built on the
vehicle. The Army vehicle chassis is used for
ISSN: 2231-5381
Generators with a provision for the exhaust and
hot air outlet with maintenance door is provided.
Mast: Mast is located between the Shelter
and Generators. For better stability and to obtain
verticality, the DF mast is located centrally. The
Army vehicle chassis is fixed with Manual
leveling Jacks which can be easily operated by the
Operator. By leveling the Army vehicle chassis,
the Mast is made Vertical.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014

THEORITICAL CALCULATIONS:
DESIGN CALCULATIONS OF ARMY
Flange Thickness of C-Section (Ft3) =
4mm

VEHICLE CHASSIS

Shear load (σ) = 24 kg(f)/mm^2

Total Load on the Chassis (w) = 4 tons

Weight trasmitted at each Point Load(W)
= w*1000/4 = 4*1000/4 = 1000 kgs

Distance between Rails(L) = 1582 mm

Distance between Shaft Loading
Moment of Inertia(MI6) = (w3*h3^3(w3-2*t3)*(h3-2Ft3)^3)/12 =
229775mm^4
 Sectional Modulus(Z6) = MI6/h3/2 =
1823.61mm^3
Required Sectional Modulus of Long
Member Box Section
Brackets(Lb) =888mm

Maximum Bending Moment(Bmax1) =
w*(L-Lb)/2 = 1000*(1582888)/2=347000 Kg-mm
 Max Bending Moment(Bmax) =
Bmax1/1000 = 347000/1000 =347 kg(f)m
 Required Sectional Modulus(Zr) =
Bmax1/σ = 14458.33333 mm^3
Sectional Modulus of flat bed C Section for

member of Chassis is constrained all the
sides Shear load (σ) = 24 kg(f)/mm^2
Long Member

Height of C-Section (h2) = 75 mm

Width of C-Section (w2) = 40 mm

Web Thickness of C-Section (t2) = 6 mm

Flange Thickness of C-Section (Ft2) =

Total Load on the Chassis (w) = 4 tons

Distance between Rail Wheels along
length (L) = 1582 mm

6mm


Moment of Inertia(MI2) = (w2*h2^3(w2-2*t2)*(h2-2Ft2)^3)/12 = 697783.5
mm^4
 Sectional Modulus(Z2) = MI6/h2/2 =
4651.89 mm^3
Considered Sectional Modulus of connecting

flange


Height of C-Section (h3) = 63 mm

Width of C-Section (w3) = 25 mm

Web Thickness of C-Section (t3) = 4 mm
Distance between Roller Support and load
Left Side (L1) = 653mm
Length of Box Section (L2) = 2460 mm
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Considered type Cantilever as the long
Distance between Roller Support and load
Right Side (L2) = 653 mm

Left Side Reaction(Rl) = w*1000/4 =
1000 Kgs
Right Side Reaction(Rr)= w*1000/4 =
1000 Kgs

Bending Moment Left Side(Bl) = Rl*L1
=1000*653 = 653000 Kg(f)-mm
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014

Bending Moment Right Side(Br) = Rr*L2

= 1000*653= 653000 Kg(f)-mm


Kgs
Maximum Bending Moment on the long
member (Bmax2) = Max(Bl, Br) = Max
(653000, 653000) = 21531250 Kg(f)-mm
Max Bending Moment(Bmb) =

Bmax2/1000 = 653000/1000 = 653 kg(f)-

Right Side Reaction(Rr)= w*1000/4 =
300 Kgs

m

Left Side Reaction(Rl) = w*1000/4 = 300
Bending Moment Left Side(Bl) = Rl*L1
=1000*300 = 120000 Kg(f)-mm
Bending Moment Right Side(Br) = Rr*L2
= 1000*300= 120000 Kg(f)-mm
Required Sectional Modulus(Z4) =
Bmax2/ σ =653000/24 = 27208.33333
mm^3
Required Sectional Modulus of flat bed Box


Maximum Bending Moment on the long
member (Bmax2) = Max(Bl, Br) = Max
(120000, 120000) = 120000Kg(f)-mm
Max Bending Moment(Bmb) =
Bmax2/1000 = 120000/1000 = 120 kg(f)-
Section
m

Required Sectional Modulus(Z4) =
Bmax2/ σ =120000/24 = 5000 mm^3
3D MODEL OF ARMY VEHICLE CHASSIS
ASSEMBLY

Considered type Cantilever as the long
member of Chassis is constrained all the
sides Shear load (σ) = 24 kg(f)/mm^2

Total Load on the Chassis (w) = 1.2 tons

Distance between Rail Wheels along
length (L) = 1576 mm

Distance between Roller Support and load
Left Side (L1) = 400mm

Fig. 1 The 3D Model of army vehicle chassis
assembly
FINITE ELEMENT ANALYSIS
Distance between Roller Support and load
Right Side (L2) = 400 mm
The material properties used for the design of
Army vehicle chassis is given below.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014
Frame: This consists of C sections made from
converted into a parasolid to import into ANSYS.
wieldable quality hot-rolled structural steel IS:
A Finite Element model was developed with shell
2062-1999, Grade A, Fe 410WA.
and mass elements. The elements that are used for
idealizing the Army vehicle chassis Assembly
Mechanical Properties:
were described below. A detailed Finite Element
Tensile Strength =
model was built with shell and mass elements to
410 Mpa
idealize all the components of the Army vehicle
Yield Strength
= 250 Mpa
Density
=
chassis. Modal analysis was carried out to find the
7850 kg/m3
first 6 natural frequencies and their mass
participations. Changes were also implemented to
The component weight is applied as Loads on the
army vehicle chassis, the distribution of the load
is shown in the below table.
shift the fundamental natural frequency.The
elements that are used for idealizing the Army
vehicle chassis are Shell 63and Mass 21.
Below Table-1 Shows the total Loads applied on
the army vehicle chassis
STATIC
ANALYSIS
FOR
EQUIPMENT
LOAD
Total
S.No
Equipment Operators
1.
Generator+Generator Cover
600
2.
Battery Bank
400
3.
Mast+Accessories
775
Weight(kg)
Structural static analysis is performed on
the army vehicle chassis by applying all the
weights of the components which are mounted on
the chassis. From the analysis the maximum
stresses and deflections are identified and
documented.
The
boundary
conditions
and
loading applied on the chassis are shown in the
4.
Flat bed
710
5.
Shelter
1200
TOTAL
3685
below figure.
FINITE ELEMENT MODELING:
3D model of the Army vehicle chassis assembly
was developed in UNIGRAPHICS from the
design calculations done. The model was then
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014
STATIC ANALYSIS IN DEPLOYMENT
MODE
During deployment condition the vehicle is lifted
from ground with jacks. The purpose of this
condition is when the vehicle is on the slanting or
rugged ground, the mast will becoming slant. To
keep the mast always vertical the vehicle is lifted
on the leveling jacks. During this condition Loads
on Army vehicle chassis include equipment as
well as bare vehicle weight and wind load. The
boundary conditions and loading applied on the
chassis are shown in the below figure.
Fig. 2 Boundary conditions and loading
conditions applied for static analysis
Fig. 4 Boundary conditions and loading applied
for static analysis in deployment condition
Fig.3 Deflections and stress plots for static
analysis
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014
From the above results obtained in static analysis
in deployment condition some high stressed
locations were observed and to reduce the stresses
additional C-sections were introduced as shown in
the below figure. From the modal analysis it is
also observed that there is a huge deflection at the
center part of the chassis. To avoid this deflection
and to increase the fundamental natural frequency
an additional support structure is added as shown
in
the
below
figure.
Fig. 5 Deflections and stress plots for static
analysis during deployment
MODAL ANALYSIS
Modal analysis was carried out to
determine the first 10 natural frequencies and
mode shapes of a structure. A Block Lanczos
mode-extraction method is used to extract the
frequencies and mode shapes. Eigen values and
their mass participations in all the three directions
for the first 10 natural frequencies are listed in the
below Table.
Fig.7 Modifications made on the chassis
Fig. 6 1st Mode shape@12.3Hz
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014
MODE
FREQUENCY
PARTICIPATION FACTOR
X-Dir
Y-Dir
Z-Dir
1
12.3
-5.37E-02
1.7289
-8.89E-02
2
18.2
0.31493
-5.46E-02
0.8925
3
19.9
-0.27852
-1.40E-03
-0.31352
4
29.1
0.89699
0.51368
0.11269
5
34.2
-1.1051
0.32009
0.88775
6
39.7
0.21158
-0.16863
0.6775
7
57.6
0.50195
0.12155
-0.11829
8
70.6
0.85297
-3.36E-02
0.39199
9
77.5
0.15373
3.47E-02
0.62358
10
83.5
0.19549
3.72E-03
1.03E-02
Table. 2 Eigenvalues and Mass participation in X, Y and Z directions
EFFECTIVE MASS
X-Dir
Y-Dir
Z-Dir
2.88E-03
2.98922
7.90E-03
9.92E-02 2.98E-03
0.79656
7.76E-02 1.96E-06 9.83E-02
0.80459
0.26387
1.27E-02
1.22122
0.10246
0.7881
4.48E-02 2.84E-02
0.45901
0.25195
1.48E-02 1.40E-02
0.72755
1.13E-03
0.15366
2.36E-02 1.20E-03
0.38885
3.82E-02 1.39E-05 1.06E-04
for the modified chassis as compared to the original
one.
RESULTS AND DISCUSSIONS
In this project manual design calculations of the
chassis are performed initially and the same design
has been validated using finite element analysis. The
following analyses were carried out to study the
structural integrity of the “Army vehicle chassis” to
identify the maximum stressed locations under
various loading conditions. Modal analysis was also
carried out to find the first 10 natural frequencies to
understand the dynamic behavior of the structure.
Based on the results some changes were proposed and
implemented on the chassis. It was observed that there
Fig.8 Comparison graph of natural frequencies for
was a 65% reduction in the stress value and 50%
original and modified chassis
reduction in the total deflection for the static analysis
CONCLUSIONS
with equipment load condition.
It was also observed that the there is a 21%
Chassis is a major component in a vehicle
reduction in the stress value and 20% reduction in the
system. For vehicles, chassis consists of an assembly
total deflection value for the static analysis in
of all the essential parts of a vehicle (without the
deployment condition. It was also observed that the
body) to be ready for operation on the road.
fundamental natural frequency is increased by 22%
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 9 Number 3 - Mar 2014
In this paper the army vehicle chassis has
Authors Profile:
been designed and optimized to reduce the stresses
Tandra Naveen kumar has performed
this work while he is pursuing post
graduation in CAD/CAM department at
Holy Mary Institute of Technology and
Science, Jawaharlal Nehru technological
University, Hyderabad, India
and deflections. Optimization was also done to
increase the fundamental natural frequency. Initially
the design was done with theoretical calculations.
From the theoretical calculations the design
was developed and the same design was validated
using finite element analysis. Optimization was also
done based on the finite element analysis results.
From the finite element analysis results it is
concluded that the optimized modified army vehicle
N.JEEVAN KUMAR completed his
B.TECH
in
year
1995
from
NAGARJUNA UNIVERSITY and HE
completed his M.TECH(CAD/CAM) in
the year 2001 from JNTU,HYD. Now
persuing Ph.D from
OSMANIA
UNIVERSITY. Having total 17 years of
experiance .out of which 12 years of teaching and 5years of
industry.
chassis safe for the given operating conditions.
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