Design and Analysis of Composite Leaf Spring: A Review

IJRMET V ol . 4, I ssuE 2, M ay - ocTobER 2014
w w w . i j r m e t . c o m InternatIonal Journal of research In MechanIcal engIneerIng & technology 67
ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)
Design and Analysis of Composite Leaf Spring: A Review
1Kiran K. Jadhao, 2Dr. Rajendra S. Dalu
1Dept. of Mechanical Engineering, Babasaheb Naik College of Engineering, Pusad, India
2Professor and Head, Mechanical Engineering, Govt. College of Engineering,Amravati, India
Abstract
Automobile industry has shown increased interest in the
replacement of conventional materials with composites due to its
property of high strength to weight ratio. Reducing weight while
increasing or maintaining strength of products is getting to be
highly important research issue in this modern world. Composite
materials are one of the material families which are attracting
the researchers and giving solutions for such issues. This paper
presents literature review on: suitability of composite materials
for leaf spring in automobile, compare its result with conventional
steel leaf spring, design and analysis of composite leaf spring.
Identify gaps in literature and present proposed research plan.
Keywords
Leaf Spring Glass Fiber Reinforced Material, Composite Material,
FEA, ANSYS, Static and Fatigue Analysis
I. Introduction
In order to conserve natural resources and economize energy,
weight reduction has been the main focus of automobile
manufacturers. Weight reduction can be achieved primarily by
the introduction of better material, design optimization and better
manufacturing processes. The achievement of weight reduction
with adequate improvement of mechanical properties has made
composite a very good replacement material for conventional steel.
A composite is composed of a high-performance fibers such as
carbon, Kevlar, graphite or glass in a matrix material that when
combined provides better properties compared with the individual
materials by themselves. The composite materials are used in
structural application areas, such as in aircraft, space, automotive,
for sporting goods, and marine engineering .The various type
of glass fibers available are Carbon fiber, C-glass, S-glass and
E-glass. However, carbon/epoxy material is better than other fibers
but because of its high cost, it has limited applications. Favorable
relation between cost and properties of a material can be obtained
with E-glass fiber / epoxy.
Leaf spring is mainly used in suspension system to absorb
shock loads in automobiles. It carries lateral loads, brake torque,
driving torque in addition to shock absorbing. The various studies
were conducted on the application of composites materials for
automobile suspension system (B. P. Johnson 1986, Daugherty
R. L. 1981)
The major step of composite in automotive business is extension
of use in to truly structural application such as primary body
structure and to chassis and suspension system. These are the area
which has to sustain all major road load inputs and impact loads.
Leaf spring is one of the potential items for weight reduction in
automobile as it accounts for ten to twenty percent of the un-sprung
weight. This helps in achieving the vehicle with improved riding
qualities. These are widely used in light motor vehicles, heavy
duty trucks and in rail systems to absorb shock loads and vibration.
Generally, leaf springs have been classified as mono- leaf spring
and multi-leaf spring and based on the spring’s ends: they are
double-eye leaf springs and open-eye leaf springs.
It is well known that springs are designed to absorb and store
energy and then release it. It can be observed that material having
lower modulus of elasticity and density will have a greater specific
strain energy capacity. Thus, the introduction of Fiber Reinforced
Plastics (FRP) made it possible to reduce the weight of the leaf
spring without any reduction on load carrying capacity and
stiffness. FRP material’s have high elastic strain energy storage
capacity, high strength-to-weight ratio, fatigue resistance.
II. Literature Review
Literature has been classified into three categories: composite
materials for leaf spring, design and optimization of composite
leaf spring, and analysis of composite leaf spring. Each one is
explained in brief below.
A. Composite Materials for Leaf Spring
The composite material is having distinguishing characteristic
such as, high strength to weight ratio, superior fatigue strength
,excellent corrosion resistance and higher natural frequency
so it makes composite materials are excellent for leaf spring.
(BeardmoreP,Johnson1986).Application of composite material
reduces the weight of spring without reducing load carrying
capacity and stiffness in automobile suspension system. The
leaf spring should absorb vertical vibration due to irregularities
by means of variation in the spring deflection so that potential
energy is stored in the spring as strain energy and released slowly
(Daugherty, 1981; Breadmore, 1986; Morris, 1986; Corvi, 1990;
G. Siddaratha, 2006).Table1 shows various composite materials
proposed by researchers for leaf spring.
Table 1: Composite Materials Proposed for Leaf Spring
Sr
No
Composite
Materials Researcher
1
(CFRP) Carbon
Fiber Reinforced
Plastic
P.Beardmore(1986)
2
S2-glass fiber/
Epoxy and E-glass/
Epoxy
W.J. Yu. Kim(1988)
3 Glass fiber, Carbon
fibre Andra Corvi(1990
4
E-glass fibre
with two layer of
bidirectional fabric
Erol Sancatar (1999)
5 E-glass/Epoxy
Max. X.Sardou et.al (2000),M.
Senthil (2007),Mahmood
Shokrieh (2003), Dara Ashok
(2012), Laxinarayana (2012),
Asish Amrute(2013), Shishay
Amare Gebremeskel(2012)
6 E-glass/Epoxy and
carbon fiber/Epoxy H.A.Al. Qureshi(2001)
7
E-glass/Epoxy and
Woven roving/
Epoxy
G Gular Siddaramanna
et.al(2006)

IJRMET V ol . 4, I ssuE 2, M ay - ocTobER 2014 ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)
w w w . i j r m e t . c o m68 InternatIonal Journal of research In MechanIcal engIneerIng & technology
8 Woven glass fiber
baric
E.Mahdi et.al (2006); Abdul
Rahim (2010 )
9
20% glass fiber
reinforced
polypropylene C.Subhramian ,et.al (2011)
10
Glass/Epoxy,
Graphite/Epoxy,
arbon/Epoxy,
Kelvar/ Epoxy,
Boron /Aluminium
B.Ragu Kumar et.al (2013)
11
E-Glass/Epoxy,
C-Glass/Epoxy,
S-Glass
/Epoxy
B.Vijaya Lakshmi1 I.
Satyanarayana(2012)
12 Carbon/epoxy Parkhe Ravindra and Sanjay
Belkar (2014)
13
bidirectional
carbon-glass
reinforced plastic
(C-GFRP) and
bidirectional glass-
carbon reinforced
plastic (G-CFRP)
S.Rajesh1 and G.B.Bhaskare
(2014)
14
C-glass/epoxy
composite leaf
spring
Mhaske Raman, Nimbalkar
et.al (2014)
B. Design and Optimization of Composite Leaf Spring
Usually leaf spring in vehicle is assumed as a simply supported
beam which is subjected to both bending stress and transverse
shear stress. Usually, three design approaches have been tried
to accessed: (i) constant thickness, varying width (ii) constant
width, varying thickness and (iii) constant cross-section design.
In 1981, a composite suspension of curved beam type was
developed for family car (Daugherty 1981),in another design
(Andrea Corrvi,1990) the thickness of spring was kept constant
and the theoretical details of composite mono leaf spring were
reported using a program tool. Over a period of time GFRP double
tapered beam and spring with variable thickness were designed and
optimized for automobile suspension assuming similar geometrical
and mechanical properties as that of multi steel (Yu and Kim,
1988; H. A. Qureshi, 2001). From the better material utilization
perspective and avoiding material wastage, spring designed was
introduced in two stages. In first stage, using E- glass fiber/vinyl
ester with two layer of bidirectional fabric layer was used and in
second stage, leaves of spring in width and thickness direction
were tapered. This produced even distribution of stress over the
spring (Erol Sancaktar, 1999). An optimal spring width decreases
hyperbolically and thickness increases linearly from spring end
towards the axle seat but deflection of composite spring was lower
than steel leaf spring (M.M.Shokrieh2003).
An optimized design of composite leaf spring is required to
balance the weight and stiffness of composite leaf spring. The
spring was preferred in certain shapes these included like C-type,
Elliptical, parabolic and taper shape. The light and low cost
composite compression C-spring was designed and tested for
static, fatigue and road test (X.Sardou, et.al, 2000). Secondly
parabolic taper leaf spring has been accepted for Tata Motors by
(Sachin, et.al, 2005) and obtained the best compromise between
stress induced and stiffness of spring. On the other hand, the high
spring rate together with weight saving achieved with elliptical
spring (E.Mahdi, O.M.Set et. al; G.Goudah, et. al 2006). But the
influence of elliptical ratio as 0.5 and spring with open eye end
reduces the problem of delamination in spring (J.P.Hou, 2007;
Abdul Rahim, et.al, 2010). In another configuration of leaf spring
a semielliptical multi- leaf steel leaf spring has been designed
under same load carrying condition and the performance of both
springs has to be studied and found that composite multi spring is
an effective replacement for conventional steel leaf spring (Dara
Ashok, et al 2012). Parabolic leaf spring plays a vital role in the
suspension systems, since it has an effect on ride comfort and
vehicle dynamics and suitable in terms of economy and light
weight of spring (Mahammood Ashique et al., 2007).
Now a days popular technique namely formulation and solution
techniques are used for weight optimization. The Genetic
Algorithm (GA) approach was used for designing the composite
leaf spring with constant cross sectional and it has been found
with this technique that weight reduction of 93% is achieved in the
spring(Shivashankar, Vijayarangan, et.al 2007).RecentlyParticle
Swarm Optimization (PSO) and Simulated Annealing (SA)
approaches are used for design optimization of composite Leaf
Springs. It is helpful to determine the best combination of design
variables like center width and thickness of composite spring. It
is found that using Particle Swarm Optimization technique the
composite spring produced less deflection ,stress & weigh nearly
about 85%,and while with Simulated Annealing weight is 78.8 %
compared to steel leaf spring (Simran Jeet Singh, Meenu Gupta
2013).
Researchers have employed a wide variety of methods and
measures to investigate the performance parameters of composite
leaf spring a brief summary are given below in table2.
Table 2: Performance Parameters of Composite Leaf Spring (1986-
2014)
Sr.
No
Tested Performance
parameters Researchers
1 Noise Vibration and
Harshness C.J. Morries 1986
2 Fatigue Life and
Natural Frequency
Gulur Siddarmanna 2006,
M. Senthil Kumar 2007
3 Strain J.P. Hou 2007
4 Maimum Load, Stress,
Deflection, Weight
I.Venkata Nag (2010),
M.Venkata san(2012), B.
Raghu Kumar et al. (2013 )
5 Stiffness
Erol. Sancakart (1999), C.
Maddan Mohan Reddy et.al
(2013 )
6 Vonmisses stress,
Normal stress Vinkel Arora 2011
7 Endurance strength
,Maximum Load C. Subbramanna 2011
8 Load and Deflection
Parkhe Ravindra and Sanjay
Belkar (2014) ,R. Pradeep,
et.al (2013), Karthik
Badugu, et.al (2013)
9 Principle stress R. D. V. Prasad et.al (2013 )
C. Analysis of Composite Leaf Spring
The primary goal of analysis is to obtain information about the
relevant performance parameters of leaf spring under different

IJRMET V ol . 4, I ssuE 2, M ay - ocTobER 2014
w w w . i j r m e t . c o m InternatIonal Journal of research In MechanIcal engIneerIng & technology 69
ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)
loading condition. These data can be of following: stresses,
deflection, maximum and minimum stress induced, natural
frequency and weight of spring. The leaf spring was analyzed by
many researchers using analytical, numerical and experimental
approach. In modern design, a wide range of software packages
are being used, such as CATIA, PRO/Engineer, CAE, and ANSYS.
The Analysis of composite leaf spring has become essential for
comparative evaluation with conventional steel leaf spring.
The GFRP composite spring was subjected to static analysis to
determine important attribute: deflection and bending stress. The
result of analysis shows that impressive weight saving in leaf
spring has been observed compared to conventional multi steel
leaf spring ( H.A.Qureshi, 2001, Pozhilla Rosa T. 2013, Pankaj
Saini et.al Karthik. Badugu1, et.al 2013)
A prediction of fatigue life based on finite element analysis was
presented by F.N. Ahmad et al. (2009). The main factors that
contribute for fatigue failure were observed to be number of load
cycle experienced, range of stress and maximum stress experienced
in each load cycle and presence of local concentration. Fatigue
analysis were also carried out on constant cross section GFRP
leaf spring (M.Senthil 2007, Vinkel Arora et.al 2011, Krishna
Kumar2012, Dara Ashok 2012 M.Venkatashan et.al 2012 ; B.Ragu
2013, Keshav and Murthy 2013). As testing of leaf spring using
regular procedure consumes a lot of time therefore sometimes
standard SAE manual outlined procedure was used to conduct
fatigue analysis on both composite and steel leaf spring. It was
found that fatigue life of composite spring was higher than steel
leaf spring (M.SenthilKumar, 2007). When hybrid composite
elliptical spring was subjected to fatigue analysis, it indicates
better fatigue behavior than conventional composite leaf and coil
spring (E. Mahadi, et.al 2006). Makarand B.Shirk et.al (2012)
found that life of composite leaf spring was109cycles as compared
to 106 cycles for steel leaf-spring. The Behavior of seven steel and
multi-composite leaf spring have been investigated using ANSYS
tool (Joo -Teck Kuech,2012). The main center of attention was
given to the effect of composite materials and orientation of fiber
on the fatigue performance of spring. It is required that when
spring is subjected to shock load the passenger seating in vehicle
must get free form this vibration. In general, the road irregularities
usually have maximum frequency of 12 Hz (Yu Kim, 1988). In
order to provide comfort ride to the passengers in vehicle the leaf
spring is designed in such a way that the natural frequency must be
maintained within allowable limits to keep away from resonance.
The natural frequency of composite leaf spring observed to be 1.2
times maximum road frequency and therefore resonance could not
occurred(M. Senthil Kumaret.al 2007,Shokerich,2003,V. Laxmi
Narayana, 2012).The modal analysis in structural mechanics
was carried out to determine the natural mode shapes and
frequencies of an object or structure during free vibration. In
general, it is common to use the finite element method to perform
this analysis because, like other calculations using the FEM, the
object being analyzed can have arbitrary shape and the results of
the calculations are acceptable. The natural frequency and mode
shape of spring taking into consideration road surface model was
determined for passenger car by means of finite element analysis
(I. Rajendranan, et.al, 2002).Table 3. shows major work completed
so far by researchers on analysis of Composite Leaf Spring.
The harmonic and shock analysis were carried out for two layered
and five layered composite leaf spring. The change in amplitude
of spring was observed for the both type of composite leaf
spring. Furthermore during shock analysis, it has been observed
that displacement of springs was changed as time progressed
(K.A.Saianurag, 2012). It has been found that several papers were
devoted to the study of behavior of spring through different analysis
such as, static, fatigue, and modal which was projected only for
unidirectional fiber orientation. Nevertheless, unidirectional fiber
orientation may weaken joint area thus strengthening of the joint
is required.
III. GAPS in Litreture
Inadequate work has been done on modal analysis, creep1.
analysis, and Impact analysis for composite leaf spring
Very Little work has been done on effect of different fibers2.
reinforcement type, fiber orientation and stacking sequence
on performance of composite leaf spring
Little work has been carried out on matrix cracking,3.
delamination, and stress concentration at hole in composite
leaf spring
Very less work has been carried out on Integral Eye design4.
of composite leaf spring
Long term practical durability and effect of environmental5.
parameters on composite leaf spring has not been studied
Torsional behavior of composite leaf spring was not much6.
studied
Investigation required to improve fabrication process to7.
reduce voids which are developed at surface of composite
leaf spring
Less work has been carried out on problem like spring failure8.
mode i.e. inter-laminar shear stress
Interleaf friction in multi-leaf spring has not been much9.
studied
Table 3: Summary of Major Work on Analysis of Composite Leaf
Spring
S.No. Research Objectives Researchers
01 To study Fatigue life of
spring Hawang. W.(1986)
02
To Optimize geometry
of composite leaf
spring
Yu.Kim (1988), Erol
Sancatar (1999), I.
Raendran, S. Vijayarangan
(2001) M.M. Shokrieh
2003),Shivshankar,V.
(2007)
03
To evaluate design
parameters of leaf
spring
Andra Corvi(1990), Joo.
Teck.(2012)
04
To design and analyse
GFRP mono leaf
spring
G Gular Siddaramanna
et.al(2006) M.
Senthil Kumar, S.
Vijayarangan(2007)
Jaydeep J. Patil,. S. A. Patil
(2014)
05 Study performance of
C- type leaf spring Max. X.Sardou et.al(2000)