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I N T E R N A T I O N A L J O U R N A L F O R R E S E A R C H I N A P P L I E D S C I E N C E AN D E N G
I N E E R I N G T E C H N O L O G Y (I J R A S E T)

Design and Analysis of Multi Leaf Springs Using

Composite Materials
Ganesh.K1, Gembiram.M2, Elayaraja.R3, Saravanan.R4, Murali.K5
1234
UG Student Department ofMechanical Engineering,
5
Asst.Professor Department of Mechanical Engineering,
University College of Engineering, Arni, Thatchur-623326
TamilNadu, India

Abstract— Weight reduction has been the main/primary focus of automobile manufactures. The automobile industries have
shown interests in replacement of steel springs with composite leaf springs due to high strength to weight ratio. The objective of
this paper is to compare the load carrying capacity, stiffness and weight savings of composite leaf spring with that of steel leaf
spring. This work is carried out on multi leaf of commercial vehicle. Mathematical calculations are carried out for design the
multi leaf spring. The materials of the leaf springs are SAE 9260 and Glass fiber reinforced epoxy to be taken for comparative
study. A Finite element approach for analysis of a multi leaf springs using Ansys software is carried out. The leaf spring model
is generated by using Pro/E and imported in Ansys. Harmonic analysis for vibration due to road irregularities and static analysis
for gross vehicle mass load analysis are carried out for both materials, and comparative behaviors are observed such as stress
and deflection of the multi leaf spring.

Key Words— Multi leaf springs, Steel Leaf Springs, Composite Leaf Springs, Harmonic analysis, Static analysis, Pro/E, Ansys.

capacity, good strength to weight ratio, good riding properties

1. INTRODUTION and, density good modulus of elasticity.
Composite materials are the one of the main applications of the
aerospace, automobiles and marine Industries. Because of their 1.2 LITERATUREREVIEW
less weight, good stiffness and less corrosive properties. Weight M.VENKATESAN et.al. (2012)describes design and
reduction is one of the major factors of that one. It results in less experimental analysis of composite leaf spring made of glass
fuel consumption; economize maintenance of vehicle and fiber reinforced polymer. The objective is to compare the load
optimum utilization of natural resources. The suspension leaf carrying capacity, stiffness and weight savings of composite leaf
spring is one of the potential items for weight reduction in spring with that of steel leaf spring. The design constraints are
automobile as it accounts for ten to twenty percent of the stresses and deflections. The dimensions of an existing
unspring weight. This helps in conventional steel leaf spring of a light commercial vehicle are
taken. Same dimensions of conventional leaf spring are used to
achieving the vehicle with improve good riding qualities. As we fabricate a composite multi leaf spring using E- Glass/Epoxy
know that springs, are designed for absorb and store energy after unidirectional laminates. Static analysis of 2-D model of
it releases slowly. Hence, the strain energy of the material conventional leaf spring is also performed using ANSYS 10 and
becomes a major factor in designing the springs. The compared with experimental results. Finiteelement analysis with
conventional steel leaf spring is replaced with composite full load on 3-D model of composite multi leaf spring is done
material, because of their more elastic strain energy storage using ANSYS 10 and the analytical results are compared with
experimental results. Compared to steel spring, the composite

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leaf spring is found to have 67.35% lesser stress, 64.95% higher removed. Applications of leaf springs are as follows to cushion,
stiffness and 126.98% higher natural frequency than that of absorb or control energy due to either Shock or vibration as in
existing steel leaf spring. A weight reduction of 76.4% is automobiles. The leaf springs supposed to carry loads, brake
achieved by using optimized composite leaf spring. torque, driving torque. The leaf springs used are single or multi
U.S.RAMAKANTH et.al. (2013)project work is carried out on leaf springs are there. Today leaf springs are still used in
multi leaf springs having nine leaves used by a commercial commercial vehicles such as cars, vans and trucks, and railway
vehicle. A Finite element approach for analysis of a multi leaf carriages. For heavy vehicles, they have the advantage of
springs using Ansys software is carried out. The model is spreading the load more widely over the vehicle's chassis. The
generated using solid works and imported in Ansys. The main importance of leaf spring is to carry bump loads (i.e. due
material of the leaf springs is 65Si7 (SUP9), composite leaf to road irregularities), supports the chassis weight, controls axle
springs and hybrid leaf springs. Fatigue analysis of leaf springs damping, controls braking forces, and to provide better
is carried out for steel leaf springs, and Static analysis for steel suspension. Leaf springs are designed in two ways:
leaf springs, composite leaf springs and hybrid leaf springs. 1. Mono Leaf Spring
Under the same static load conditions the stresses in leaf springs 2. Multi Leaf Spring
are found with great difference. Stresses in composite leaf The Multi Leaf Spring is made up of several steel plates of
springs is found out to be less as compared to the conventional different length stacked together, while mono-Leaf spring is
steel leaf springs, also a new combination of steel and composite made up of single steel plate.During normal operation, the
leaf springs (hybrid leaf springs) are given the same static spring compressestoabsorb Road shock. The leaf spring bends
loading and is found to have values of stresses in between that and slide on each other allowing suspensionmovement. Leaf
of steel and composite leaf springs. springs Can serve locating and to some extent damping as well
Bhushan B. Deshmukhet.al. (2011)Weight reduction can be as springing functions. The leaf spring absorbs the Vertical
achieved primarily by the introduction of better material, design vibrations and impacts due to road irregularities by means of
optimization and better manufacturing processes. The vibrations in the spring deflection So that the potential energy is
introduction of FRP material has made it possible to reduce the stored in spring as strain energy and then released slowly.
weight of spring without any reduction on load carrying
capacity. The achievement of weight reduction with adequate 1.4 COMPOSITE MATERIALS
improvement of mechanical properties has made composite a A composite material is defined as a material composed of two
very good replacement material for conventional steel. Selection or more constituents combined on a macroscopic scale by
of material is based on cost and strength of material. The mechanical and chemical bonds. Composite materials are
composite materials have more elastic strain energy storage composed of inclusions suspended in a matrix. The constituents
capacity and high strength to weight ratio as compared with retain their identities in the composite. In general the
those of steel, so multi-leaf steel springs are being replaced by components can be physically identified and there is an interface
mono-leaf composite springs. The paper gives the brief look on between them. Some of the composite materials offer a
the suitability of composite leaf spring on vehicles and their combination of strength and modulus that are either comparable
advantages. The objective of the present work is design, analysis to or better than any traditional metallic materials which we
and fabrication of mono composite leaf spring. The design have earlier. Because of their low specific gravities, strength
constraints are stress and deflections. The finite element analysis weight-ratio and modulus of elasticity. These composite
is done using ANSYS software. The attempt has been made to materials are better than those of metallic materials. The fatigue
fabricate the FRP leaf spring economically than that of strength and weight ratios as well as fatigue damage tolerances
conventional leaf spring. of composite laminates excellent. For this reasons, fiber
composite have emerged as a major class of structural material
1.3 LEAF SPRING and are either used or being considered as substitutions for metal
Leaf springs are also known as flat springs or carriage springs in many weight-critical components in aerospace, automotive
.Leaf spring is an elastic body, whose functions to distort when and other industries. Some other characteristic of many fiber
load applied and to recover its original shape, after load is reinforced composites is their high internal damping. This

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results to better vibration energy absorption within the material molding injection time is too long as compared to the resin set-
and results in reduced transmission of noise and vibration to up time, limiting laminate thickness. Injection forces resin
neighboring structures. High damping capacity of composite through a thicker ply stack, thus depositing the resin where in
materials can be beneficial in many aerospace, automotive the laminate structure before gelatin occurs. Specialized epoxy
applications in which noise, vibration, strength and hardness is a resins have been developed to customize lifetimes and viscosity.
critical issue for passenger comfort. Among the other
environmental factors that may cause degradation in some of the 3. SPECIFICATION OF MULTI LEAF SPRING
mechanical properties of some polymeric matrix composites are
elevated temperatures, corrosive fluids, and ultraviolet rays. In Table.1 shown various parameters of leaf spring
many metal matrix composites, oxidation of the matrix well as
adverse chemical reaction between fibers and matrix are of great S.NO PARAMETER VALUE
concern at high temperature applications.
1. Total length of the spring (Eye 1020mm
2. MATERIALS SELECTION
The material used for leaf springs is usually a plain carbon steel to Eye)
having 0.90 to 1.0% carbon. The leaves are heat treated after the
forming process. The heat treatment of spring steel produces 2. No. of full length leave (Master 1
greater strength and therefore greater load capacity, greater Leaf) (nf)
range of deflection andbetter fatigue properties. According to 3. No. of gradual leaves (ng) 4
Indian standards, the recommended materials are:
A. For automobiles: 50 Cr 1, 50 Cr 1 V 23, and 55 Si 2 Mn 90 4. Thickness of leaf 10mm
all used in hardened and tempered state.
B.for rail road springs: C 55 (water-hardened), C 75 (oil- 5. Width of leaf spring 80mm
hardened), and 40 Si 2 Mn 90 and 55 Si 2 Mn 90).In this project
focused on automobile leaf spring, so we select
6. Maximum load given on 3065.625N
SILICOMANGANESE material for design the leaf spring and
spring(w)
another hand fiber reinforced composite selected for weight
reduction point of view. 7. Young’s Modulus of leaf spring 2x10³N/mm²

2.1. SILICON-MANGANESE Steel (SAE 9260)

Silicon increases the strength without a serious loss of ductility.
It also adds scale resistance. These steels are generally heat 4. FINITE ELEMENTANALYSIS
treated to specific properties. Manganese is one of the least Finite element structural analysis is a method of predicting the
expensive means of increasing harden ability at a given carbon behavior of a real structure under specified load and
content. It can also enhance machinability in the presence of displacement conditions. The finite element modeling is
sulfur. Chemical composition in weight percentage is C-0.6%, generalization of the displacement or matrix method of
Si-1.65% and Mn-0.85%. structural analysis to two and three-dimensional problems and
three -dimensional problems. The basic concept of FEM that
2.2. Glass fiber reinforced epoxy (GFRE) structure to be analyzed is considered to be an assemblage of
Epoxy-based composites have environmental, production, and discrete pieces called “elements” that are connected together at a
cost advantages over other resin systems. Epoxies also allow finite number of points or nodes. The finite element is a
shorter cure cycles, increased durability, and improved surface geometrically simplified representation of a small part of the
finish. Prepare operations further reduce processing time over physicalstructure. Discretizing the structure requires experience
wet lay-up systems. As turbine blades pass 60 meters, infusion and complete understanding of the behavior of the structure can
techniques become more prevalent; the traditional resin transfer behave like a beam, truss, plate, and shell.

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5. ANALYSIS OF STEEL,COMPOSITE LEAF SPRING

ANSYS can be used for all levels of analysis,from basic
stressing to full non-linear dynamic analysis.

5.1. Structural AnalysisStructural analysis is probably the most

common application of the finite Element method. The term
structural (or structure) implies not only civil engineering
structures such as Bridges and buildings, but also naval,
aeronautical, and mechanical structures such as ship hulls,
aircraft bodies, and machine housings, as well as mechanical
components such as leaf springs, machine parts, and tools.

Fig 5.1.3 Strain in SAE 9260 Leaf spring

Fig 5.1.1 3D Meshed leaf spring model

Fig 5.1.4 Stress in Fiber Glass Reinforced Epoxy

Leaf spring

Fig 5.1.2 Stress in SAE 9260 Leaf spring

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Fig 5.1.5 Strain in Fiber Glass Reinforced Epoxy Leaf spring

Table 2 Structural analysis results of Leaf spring

Structural Analysis Results

Results SAE 9260 Leaf Glass Fiber

spring Reinforced
Epoxy Leaf
spring
Max Stress in 2477 2364
N/mm² Fig 5.2.2 Amplitude Vs. Frequency curve for SAE 9260 Leaf
Max strain 0.012389 0.010552 spring

5.2. Harmonic analysis

Harmonic response analysis is a technique used to determine the
steady-state response of a linear structure to loads that vary
sinusoid ally (harmonically) with time. The idea is to calculate
the structure's response at several frequencies and obtain a graph
of some response quantity (usually displacements) versus
frequency. "Peak" responses are then identified on the graph and
stresses reviewed at those peak frequencies.

Fig 5.2.3 Amplitude Vs. Frequency Comparison graph for Leaf

springs

6.CONCLUATION
The leaf spring based on fiber glass reinforced epoxy has a
lower mass compare with the leaf spring based on SAE 9260.
Total mass reduction obtains 22.46 kg (100.45%) by using
composite material. Reducing the leaf spring mass, in
Fig 5.2.1 Amplitude Vs. Frequency curve for Glass Fiber automobiles give better riding comfortless against hard braking
Reinforced Epoxy Leaf spring and acceleration. Reducing the mass reduce the fuel
consumption of the vehicle because engine spend less fuel to
pull its own mass of the vehicle. In other hand reduction of fuel
usage reduce the emission of the vehicle. On strength basis,

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fiber glass reinforced epoxy has a lower deformation, stress and 4. G.Harinath Gowd, Venugopal Gowd ”static analysis of
strain compare with SAE 9260. Deformation reduces up to
leaf springs”, VOL 4 8th aug-2012 IJEST
14.6%, stress reduced up to 4.67% and strain reduced up to
16.01%. Reducing the deformation, stress and strain make leaf 5. Shiva Shankar and Vijayarangan,”Mono composite leaf
spring life longer against loads.
springs for light weight vehicle design, End joint,
ACKNOWLEDGMENT analysis and testing”, Material science Vol 12 Nov 3
The authors would like to express their deep gratitude to
Mr.K. Murali Teaching fellows Department of Mechanical 2006.
Engineering, University College of Engineering, Arni for 6. Nikolas Philipson and Modelan A B“Leaf spring
technical support.
modeling”, science park S E 22307,lund Sweden

7.REFERENCES 7. I.Rajendran, S.Vijayarangan, “optimal design of

1. H.A.Al-Qureshi,”Automobile leaf spring from composite leaf springs using genetic algorithm,”
composite materials”, Journal of Material Processing Computer and Structure 79 (2001) 1121-1129
Technology 118 (2001) 58-61. 8. Hou J.P Cherrualt J Y,”evolution of the eye-end design
2. Senthil Kumar, Sabapathy Vijayarangan,” Analytical of a composite leaf spring for heavy axle loads,”
and experimental studies on fatigue life prediction of composite structure, 28,351-358(2006)
steeland composite multi-leaf springs for light 9. M.L.Agarwal, V.P.Agarwal,”A stress approach model
passenger vehicles using life data analysis”, Journal of for prediction of fatigue life by shot peening of EN45
Material Processing Technology (2001). steel spring”, International Journal of Fatigue 28
3. Daugherty.R.L,” Composite leaf springs in heavy truck (2006) 1845-1853.
applications”, International conference on composite 10. Yu.W.J, Kinm.H.C,”Double Tapered FRP Beam from
material proceedings of japan US conference, Tokyo Automotive suspension leaf springs”, Composite
1981:pp 529-538 structures 1988 pp 279-300.

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