Analysis of Steel and Composite Leaf Spring for Vehicle - IOSR Journal of Mechanical and Civil Engineering

IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
e-ISSN: 2278-1684 Volume 5, Issue 4 (Jan. - Feb. 2013), PP 68-76
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Analysis of Steel and Composite Leaf Spring for Vehicle
Ghodake A. P.*, Patil K.N.
Department of Mechanical Engineering, SND COE & RC Yeola, Nashik, India
Abstract: The Automobile Industry has shown keen interest for replacement of steel leaf spring with that of
glass fiber composite leaf spring, since the composite material has high strength to weight ratio, good corrosion
resistance and tailor-able properties. The present study searches the new material for leaf spring. In present
study the material selected was glass fiber reinforced plastic (GFRP) and the polyester resin (NETPOL 1011)
[5] is used against conventional steel. A spring with constant width and thickness was fabricated by hand lay-up
technique which was very simple and economical. The numerical analysis is carried via finite element analysis
using ANSYS software. Stresses, deflection and strain energy results for both steel and composite leaf spring
material were obtained. Result shows that, the composite spring has maximum strain energy than steel leaf
spring and weight of composite spring was nearly reduced up to 85% compared with steel material.
This paper describes design and FEA analysis of composite leaf spring made of glass fibre reinforced
polymer. The dimensions of an existing conventional steel leaf spring of a light commercial vehicle are taken for
evaluation of results.
I. Introduction
Finite Element analysis tools offer the tremendous advantage of enabling design teams to consider
virtually any molding option without incurring the expense associated with manufacturing and machine time.
The Ability to try new designs or concepts on the computer gives the opportunity to eliminate problems before
beginning production. Additionally, designers can quickly and easily determine the sensitivity of specific
molding Parameters on the quality and production of the final part. The leaf spring model is created by modeling
software like pro-E , Catia and it is imported in to the analysis software and the loading, boundary conditions are
given to the imported model and result are evaluated by post processor.
The different comparative results of steel leaf spring and composite leaf spring are obtained to predict the
advantages of composite leaf spring for a vehicle.
II. FEA (Finite Element Analysis)
FEA tool is the mathematical idealization of real system. Is a computer based method that breaks
geometry into element and link a series of equation to each, which are then solved simultaneously to evaluate
the behavior of the entire system. It is useful for problem with complicated geometry, loading, and material
properties where exact analytical solution are difficult to obtain. Most often used for structural, thermal, fluid
analysis, but widely applicable for other type of analysis and simulation
Fig.1.Typical FEA procedures by commercial software

Analysis of Steel and Composite Leaf Spring for Vehicle
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III. Materials for Steel leaf spring
Plain carbon steel, Chromium vanadium steel, Chromium- Nickel- Molybdenum steel, Silicon-
manganese steel, are the typical materials that are used in the design of leaf springs. The material selected for
steel leaf spring is 65Si7. The design parameters selected for steel leaf are listed in table 1.
Table1: design parameters of steel leaf spring
Parameters Values
Material selected Steel 65Si7
Tensile strength 1962 N/mm2
Yield strength 1470 N/mm2
Young’s modulus(E) 2e5 N/mm2
Design stress(6b) 600 N/mm2
Total length 1540 mm
Arc height at axle seat 136 mm
Normal static loading 2500 N
Available space for spring width 70 mm
Number of leaves 01
IV. Materials for Composite leaf spring
Based on the specific strain energy of steel spring and some composite materials, the E-glass/epoxy is
selected as the spring material. The parameters for composite leaf spring material are listed in table 2.
Table2: parameters of composite leaf spring
Properties Values
Tensile Strength 900 N/mm2
Compressive strength 450 N/mm2
Poisson ratio (T) 0.217
Mass density (ρ) 2.6e-10 kg/mm3
Flexural strength( ) 1200 N/mm2
Flexural modulus(E) 40000 N/mm2
V. Strain Energy
The stored elastic strain energy in a leaf spring varies directly with the square of maximum allowable
stress and inversely with the modulus of elasticity both in the longitudinal and transverse directions according to
S=σt2/2 ρ E
Where,
S is the strain energy,
σt is the allowable stress,
E is the modulus of elasticity and
ρ is the density.
Geometry of leaf spring
Figure 2 shows the imported geometry of mono leaf spring. This geometry has been created in Solid works by
taking the dimensions from the paper. [5]
Fig.2. 3-D Model of leaf spring

Analysis of Steel and Composite Leaf Spring for Vehicle
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Figure 3 shows the 3D model of leaf spring with camber of leaf spring. Total length of leaf is 1540mm and
136mm is the arc height at axel seat.
Fig.3. 3-D Model of leaf spring showing camber (136 mm) of leaf spring.
6.1 Meshed model of leaf spring
Meshing is nothing but the descritization of object into the small parts called as the element.this
analysis is limited upto the 2D analysis therefore only quard and triangular elements are used. Figure 4 shows
the meshed model of mono leaf spring with an element size of 5 mm brick mesh. Previous Studies show that the
best results are obtained using brick mesh. Considering the concept of grid independence it is been found that
this is the best suited size of mesh hence this size of mesh has been selected.
Fig.4. Meshed model of leaf spring.
6.2 Loading & Boundary Conditions:
6.2.1 Fixed Support
Fixed support has restriction to move in X and Y direction as well as rotation about that particular
point. For the leaf spring analysis one eye end of the leaf spring is fixed to the chassis of the vehicle and the
fixed support at another eye end of the leaf spring model. So this eye end of the leaf spring cannot move in any
of the directions i.e. all the degrees of freedom are blocked
6.2.2Cylindrical support
As there is shackle provided at other end of the leaf spring because of which the leaf spring only
translates in one plane and other movements i.e. degree of freedom are blocked. So with the reference of this a
cylindrical support is applied to the other eye end of leaf spring model. This support allows the movement of the
leaf spring in X axis, rotation about Z axis and fixed along Y axis.