Automobile Leaf Spring from Composite Materials - IJEAT

This paper discusses the design and experimental analysis of a composite leaf spring made of glass fiber reinforced polymer. The objective is to compare the load carrying capacity, stiffness, and weight savings of composite leaf spring with that of steel leaf spring. The paper describes the significant economic potential of polymer composite and to replace automobile components (leaf Spring) against the steel. The study demonstrated that composites can be used for leaf springs for light weight vehicles and meet the requirements, together with substantial weight savings.

International Journal of Engineering and Advanced Technology (IJEAT)
ISSN: 2249 – 8958, Volume-4 Issue-1, October 2014
16 Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
Automobile Leaf Spring from Composite Materials
Rajagopal D, Varun S, Manikanth M, Bysani Somasai Sriram Kumar
Abstract—Automobiles today are over 63% iron and steel by
weight .With rising energy and environmental concerns, as well
as increases in electronics and other on-board vehicle systems.
Vehicle light-weighting continues to be a prominent concern for
vehicle manufacturers. New structural materials - metals,
ceramics, polymers or hybrid materials derived from these, called
composites – open a promising avenue in automobile industries.
This paper describes design and experimental analysis of
composite leaf spring made of glass fiber reinforced polymer. The
objective is to compare the load carrying capacity, stiffness and
weight savings of composite leaf spring with that of steel leaf
spring and describes the significant economic potential of
polymer composite and to replace automobile components (leaf
Spring) against the steel.
Keywords: polymers, ceramics, composites, leaf spring.
I. INTRODUCTION
In order to conserve natural resources and economize
energy, weight reduction has been the main focus of
automobile manufacturers in the present scenario. Weight
reduction can be achieved primarily by the introduction of
better material, design optimization and better
manufacturing processes. The suspension leaf spring is one
of the potential items for weight reduction in automobiles as
it accounts for 10% - 20% of the unstrung weight. This
achieves the vehicle with more fuel efficiency and improved
riding qualities. The introduction of composite materials
was made it possible to reduce the weight of leaf spring
without any reduction on load carrying capacity and
stiffness. Since, the composite materials have more elastic
strain energy storage capacity and high strength to weight
ratio as compared with those of steel, multi-leaf steel springs
are being replaced by mono-leaf composite springs. The
composite material offer opportunities for substantial weight
saving but not always are cost-effective over their steel
counter parts. The leaf spring should absorb the vertical
vibrations and impacts due to road irregularities by means of
variations in the spring deflection so that the potential
Energy is stored in spring as strain energy and then released
slowly. So, increasing the energy storage capability of a leaf
spring ensures a more compliant suspension system.
According to the studies made a material with maximum
strength and minimum modulus of elasticity in the
longitudinal direction is the most suitable material for a leaf
spring. Fortunately, composites have these characteristics.
Manuscript Received on October 2014.
Rajagopal D, Department of Mechanical, Jeppiaar Engineering College,
Chennai, India.
Varun S, Department of Mechanical, Jeppiaar Engineering College,
Chennai, India.
Bysani Somasai Sriram Kumar, Department of Mechanical, Jeppiaar
Engineering College, Chennai, India.
Manikanth M, Department of Mechanical, Jeppiaar Engineering
College, Chennai, India.
II. LEAF SPRING
Leaf springs also known as flat spring are made out of flat
plates. Leaf springs are designed two ways: multi leaf and
mono-leaf. The leaf springs may carry loads, brake torque,
driving torque etc, In addition to shocks. The multi-leaf
spring is made of several steel plates of different lengths
stacked together. During normal operation, the spring
compressed to absorb road shock. The leaf springs bend
and slide on each other allowing suspension movement.
2.1 Construction of Leaf Spring
The leaves are usually given an initial curvature or
cambered so that they will tend to straighten under the load.
The leaves are held together by means of band shrunk
around them at the centre or by a bolt passing through
center. Since, the band exerts stiffening and strengthening
effect, therefore effective length of the spring for bending
will be overall length of the spring minus width of the band.
In case of a center bolt, two-third distance between centers
of U-bolt should be subtracted from the overall length of the
spring in order to find effective length. The spring is
clamped to the axle housing by means of U-bolts. The
longest leaf known as main leaf or master leaf has its ends
formed in the Shape of an eye through which the bolts are
passed to secure the spring to its supports. The other leaves
of the spring are known as graduated leaves. In order to
prevent digging in the adjacent leaves, the ends of the
graduated leaves are trimmed in various forms. Rebound
clips are located at intermediate positions in the length of
the spring, so that the graduated leaves also share the stress
induced in the full length leaves when the spring rebounds.
2.2 Materials for Leaf Springs
The material used for leaf springs is usually a plain carbon
steel having 0.90 to 1.0% carbon. The leaves are heat treated
after the forming process. The heat treatment of spring steel
products greater strength and therefore greater load capacity,
greater range of deflection and better fatigue properties.
III. COMPOSITE MATERIAL
3.1 Characteristics
A composite material is defined as a material composed of
two or more constituents combined on a macroscopic scale
by mechanical and chemical bonds. Typical composite
materials are composed of inclusions suspended in a matrix.

Automobile
The constituents retain their identities in the composite
Because of their low specific gravities, the strength weight
ratio and modulus weight-ratios of these composite
materials are markedly superior to those of metallic
materials. The fatigue strength weight ratios as well as
fatigue damage tolerances of many composite laminates
excellent. For these reasons, fibre composite have emerged
as a major class of structural material are either used or
being considered for metal in any weight critical
components in aerospace, automobile and other industries.
IV. DESIGN ANALYSIS OF LEAF SPRING
USING COMPOSITES
4.1 3D Model of a Leaf Spring
4.2 Analysis of Leaf Springs using ANSYS
All the analysis for the springs is done by using
12.0. For composite leaf spring the same parameters are
used as that of conventional leaf spring. For designing of
leaf spring the camber is taken as 200 mm. Leaf spring is
modelled in Catia software and it is imported in
12.0. The constraint is given at the two eye
of the ends is provided with translational movement so as to
adjust with the deflection. This eye end is free to travel in
longitudinal direction .This particular motion will help leaf
spring to get flattened when the load is applied. The stress
and deflection analysis is done for conventional and
composite leaf spring using ANSYS software. The results
for both composite and conventional leaf spring is compared
and given below.
4.2.1 Conventional Leaf Spring
Fig. 4.1 Stress Analysis of Conventional Leaf Spring
Automobile Leaf Spring from Composite Materials
17 Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
The constituents retain their identities in the composite.
gravities, the strength weight-
ratios of these composite
materials are markedly superior to those of metallic
The fatigue strength weight ratios as well as
fatigue damage tolerances of many composite laminates
composite have emerged
as a major class of structural material are either used or
being considered for metal in any weight critical
components in aerospace, automobile and other industries.
DESIGN ANALYSIS OF LEAF SPRING
G COMPOSITES
ANSYS
All the analysis for the springs is done by using ANSYS
.0. For composite leaf spring the same parameters are
. For designing of
as 200 mm. Leaf spring is
software and it is imported in ANSYS
.0. The constraint is given at the two eye-rolled ends. One
is provided with translational movement so as to
djust with the deflection. This eye end is free to travel in
longitudinal direction .This particular motion will help leaf
spring to get flattened when the load is applied. The stress
and deflection analysis is done for conventional and
ng using ANSYS software. The results
composite and conventional leaf spring is compared
Conventional Leaf Spring
Fig. 4.2 Deflection Analysis of
4.2.2 Composite Leaf Spring
Fig. 4.3 Stress Analysis of
Fig. 4.4 Deflection Analysis
Table 4.1 Comparision
Table 4.2 Comparision
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
of Conventional Leaf Spring
of Composite Leaf Spring
Analysis of Composite Leaf Spring
Comparision of Results
Comparision of Weight

International Journal of Engineering and Advanced Technology (IJEAT)
ISSN: 2249 – 8958, Volume-4 Issue-1, October 2014
18 Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
V. APPLICATIONS
Commercial and industrial applications of composite are so
varied that it is impossible to list them all. The major
structural application areas, which include aircraft, space,
automotive, sporting goods, and marine engineering. A
potential for weight saving with composites exists in many
engineering field. The first major structural application of
composite is the corvette rear leaf spring in Commercial.
Other structural chassis components, such as drive shafts
and road wheels, have been successfully tested in the
laboratories and are currently being developed for future
cars and vans. The metal matrix composites containing
either continuous or discontinuous fibre reinforcements, the
latter being in the form of whiskers that are approximately
0.1-0.5 μm in diameter and have a length to diameter ratio
up to 200. Particulate-reinforced metal matrix composites
containing either particles or platelet that ranges in size from
0.5 to 100 μm. Dispersion-strengthened metal matrix
composites containing particles that are less than 0.1 μm in
diameter and metal matrix composites are such as
directionally solidified eutectic alloys.
VI. BENEFITS
i. Weight reduction.
ii. High strength.
iii. Corrosiveness.
iv. Low specific gravity.
VII. CONCLUSION
The study demonstrated that composites can be used for leaf
springs for light weight vehicles and meet the requirements,
together with substantial weight savings. The future
potential for composites in these types of applications is
discussed in terms of the fabrication developments which
appear likely in the next decade. It is necessary to study the
usage of composites in improving the performance and
efficiency of these automobile components. The 3-D
modelling of composite leaf spring is done and analyzed
using ANSYS. A comparative study has been made between
composite and steel leaf spring with respect to weight, cost
and strength. From the results, it is observed that the
composite leaf spring is lighter and more economical than
the conventional steel spring with similar design
specifications. Composite leaf spring reduces the weight by
85 % for E-Glass/Epoxy, over conventional leaf spring.
REFERENCES
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Concept and Life Prediction Journal of Composite Materials, 1986.
[2] Dharam, C. K. Composite Materials Design and Processes for
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Francisco, 1978.
[3] Springer, George S., Kollar, Laszloa P. Mechanics of Composite
Structures. Cambridge University Press, New York, 2003.
[4] Al-Qureshi, H. A. Automobile Leaf Springs from Composite
Materials, Journal of Processing Technology, 2001.