International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 5 - May 2014
Optimization of Eye End Design of a Single Leaf
Spring
Jayanaidu#1, M Hibbatullah#2, P Baskar*3
#
M.Tech, School of Mechanical and Building Sciences,
*Asst.Professor, School of Mechanical and Building Sciences
VIT University, Vellore, Tamil Nadu (India)
Abstract— This paper is focused on determination of better eye
end design and better material among Titanium and Steel for a
single leaf spring. The procedure of this work is to carry out
computer aided design and analysis of conventional single leaf
spring with actual design considerations and loading conditions.
This conventional 65Si7 spring steel leaf spring model and
Titanium alloy (Ti 6Al 7Nb) with standard eye end, centred eye
end and Inverted eye end are considered. The CAD model of the
leaf springs is prepared in PRO-E and analysed using ANSYS.
Static testing and finite element analysis have been carried out to
obtain the characteristics of the spring. The standard eye and
centred eye leaf springs are subjected to similar loading
conditions. The CAE analysis of the leaf spring is performed for
various parameters like Total deflection, von-misses stress and
normal stress. The main objective of this work is to determine
the better eye end design and select the best material among Steel
and Titanium alloy and to reduce the time and cost related to
actual experimental testing by providing a CAE solution.
this purpose three different types of eye design for leaf
spring analysis were considered. These two eye design
are
1) Standard eye
2) Centred eye
3) Inverted eye
Keywords—Leaf Spring, Pro-E, ANSYS, eye design
Fig 1: Arrangement of a leaf spring
I. Introduction
Leaf spring is a simple form of a spring, commonly used
for the suspension in wheeled vehicles. An advantage of
a leaf spring over a helical spring is that the end of the
leaf spring may be guided along a definite path.
Sometimes referred to as a semi elliptical spring or cart
spring it takes the form of a slender arc-shaped length of
spring steel of rectangular cross-section. The centre of
the arc provides location for the axle, while tie holes are
provided at either end for attaching to the vehicle body.
For very heavy vehicles, a leaf spring can be made from
several leaves stacked on top of each other in several
layers, often with progressively shorter leaves. Leaf
springs can serve locating and to some extent damping
as well as springing functions while the interleaf friction
provides a damping action. It is not well controlled and
results in restriction in the motion of the suspension. For
this reason manufactures have experimented with mono
leaf spring.
For various eye designs the stresses induced in the leaf
spring are computed. As eyes have the critical areas
where the most stresses induced in a leaf spring. Thus by
changing the design of eye, stresses can be reduced. For
ISSN: 2231-5381
Fig 2: Standard eye Leaf Spring
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Fig 3: Centred eye leaf Spring
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 5 - May 2014
III. Modelling, Meshing and Analysis
Modeling: The 3 different models were made in
Pro-E software with the dimensions given below:
Part
Dimension
Leaf Span
1450 mm
Eye Outer Diameter
25 mm
Eye Inner Diameter
Leaf Thickness
23.5 mm
11 mm
Leaf Width
80 mm
Fig 4: Inverted eye leaf spring
The above figures shows different types of the eye-end
joint Fig 2 shows the standard eye which is used in leaf
spring. In joint type (Fig 3) the eye end and spring are
manufactured simultaneously from the same material.
There is no stress concentration in this type. This joint
configuration has the disadvantages of high cost and
manufacturing complexity. The dimensions of existing
conventional steel leaf springs of a light commercial
vehicle are taken and are verified by design calculations.
Static analysis of 3-D model of conventional leaf spring
is also performed using ANSYS 14. Leaf springs
industries working with 65Si7 spring steel are using a
very low factor of safety for weight reduction.
II. Materials
The basic requirements of leaf springs steel is that the
selected grade of steel must have sufficient hardenability
for the size involved to ensure a full martensitic
structure throughout the entire leaf section.
The material used is 65Si7. Titanium was also selected
because it is very light weight and comparable strength
to steel alloy.
Material
Steel (65si7)
Density, ρ
7850 kg/m3
Young’s Modulus, E
2.1X 1011 N/m2
Poission’s Ratio, µ
Spring Stiffness, K
0.266
220 N/mm
Material
Titanium (6Al7Nb)
Density, ρ
4620 kg/m3
Young’s Modulus, E
9.6 X 1010 N/m2
Poission’s Ratio, µ
Spring Stiffness, K
0.36
220 N/mm
ISSN: 2231-5381
Fig 5: Modelling of a Leaf Spring
This model was then imported to ANSYS
WORKBENCH 14 after converting it into Parasolid
form. Similarly same procedure was followed for the
other 2 models.
Meshing: The meshing was program-controlled and
coarse meshing was done on the models. The number of
nodes was 739390 and elements were 153650.
Fig 6: Meshed Leaf Spring
ANALYSIS: After the meshing was done the two eye
ends were fixed and a load of 2500N was applied at the
centre of the Leaf spring. After this the analysis was
done to find out total deformation, Maximum Stresses
and Von-Mises Stresses.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 5 - May 2014
IV. SOLUTION:
STEEL LEAF SPRING
1) Standard eye Leaf Spring
Fig 8b: Von-Mises Stress
Fig 7a: Normal stress
Fig 8c: Total Deformation
3) Inverted eye Leaf Spring
Fig 7b: Von-Mises Stress
Fig 9a: Normal Stress
Fig 7c: Total deformation
2) Centered eye Leaf Spring:
Fig 9b: Von-Mises Stress
Fig 8a: Normal Stress
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 5 - May 2014
Fig 9c: Total Deformation
Fig 10c: Total Deformation
Titanium Leaf Spring:
1) Standard eye leaf spring:
2) Centred eye Leaf Spring:
Fig 10a: Normal Stress
Fig 11a: Normal Stress
Fig 10b: Von-Mises Stress
Fig 11b: Von-Mises Stress
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 5 - May 2014
Fig 11c: Total Deformation
Fig 12c: Total Deformation
3) Inverted eye Leaf Spring
V. Table and Discussion
Material
Type of
leaf
spring
Total
Deformation
(mm)
Maximum
Stress
(N/m2)
Steel
Standard
eye
Centred
eye
Inverted
eye
Standard
eye
Centred
eye
Inverted
eye
3.38
7.00
7.3716
X
107
1.1766
X
107
9.5206
X
107
7.628 X 107
0.12
1.201 X 107
12.77
9.814 X 107
Steel
Steel
Titanium
Titanium
Fig 12a: Normal Stress
Fig 12b: Von-Mises Stress
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Titanium
0.06
6.18
VonMises
Stress
(N/m2)
6.7615
107
1.0975
107
1.0072
108
6.8980
107
1.1073
107
1.0392
108
X
X
X
X
X
X
Here, the total deformation represents
the maximum deformation occurring at any part of the
spring. For all the springs and for both the materials the
maximum total deformation is at the center. While the
maximum stress here represents the normal stress on the
x- axis and is found to occur maximum at the
intersection of eye with the leaf. Similar is the case for
Von-Mises Stresses.
As titanium is lighter than steel it can be used in the
form of centred eye design instead of the conventional
leaf springs i.e. standard leaf spring of steel, this will
reduce the weight of the unsprung mass which will
increase the efficiency of the vehicle. At present
titanium alloy leaf springs are being incorporated into
high performance and sports cars.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 5 - May 2014
VI. Conclusion
1. The least deformation of 0.06 mm was found in
the centred eye leaf spring made of steel alloy.
2. The least of maximum Normal stress were
induced in centred eye leaf spring made of steel.
3. The least of Von-mises stresses were induced in
the centred eye leaf spring made of steel.
4. The maximum deformation of 12.77 mm was
found in the inverted eye leaf spring of titanium.
5. The maximum Normal stresses were induced in
the inverted eye leaf spring made of titanium.
6. The maximum Von-mises stress was induced in
the inverted eye leaf spring made of titanium.
7. The maximum deformation and the stresses
induced in the centred eye leaf spring made of
titanium were less than that of the normal eye
leaf spring made of steel.
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