design and analysis of multi leaf spring

1. PROJECT
ON
DESIGN AND ANALYSIS OF
COMPOSITE LEAF SPRING

2. TOPICS:
• Abstract
• Introduction
• Literature Review
• Composite Materials, FRP
• Composite Leaf Springs
• Problem Definition and Methodology
• Project Overview
• Material Properties
• Design Calculations
• Modelling
• Analysis
• Results
• Merits and Demerits
• Future Scope
• References

3. ABSTRACT:
In recent year automobile industries are mostly concentrating on
weight reduction and in improving the riding quality . To reduce
vehicle weight, three technique shave been studied rationalizing
the body structure , utilizing light weight materials for parts and
decreasing the size of the vehicles. In this approach by introducing composite
materials into automobile industries, which is having low
cost, high strength to weight ratio and excellent corrosive resistance
can fulfill the requirement. The suspension leaf spring is one of the
potential entities for weight reduction in automobiles as it results in
large unstrung mass. The introduction of Fiber Reinforced Plastics (FRP)
is used to reduce the weight of the product without any reduction on
load carrying capacity and spring rate. As the materials high strain
energy storage capacity and high strength-to-weight ratio compared
to steel, multi-leaf springs are being replaced by mono-leaf FRP spring .
FRP springs also have excellent fatigue resistance and durability.

4. INTRODUCTION:
LEAF SPRING:
• A leaf spring is a simple type of suspension spring commonly used in
heavy duty vehicles.
• Leaf springs also known as flat springs are made as springs made of
flat plates.
• Leaf springs are designed two ways multi – leaf and mono – leaf.

5. TYPES OF SPRING LEAVES:
• Double eye
• Slipper – open end eye
• Slipper – hook end
• Slipper – flat end
• Slipper – radius end

6. Double Eye Leaf pring Slipper – open end eye
Slipper – hook end leaf spring Slipper – flat end Leaf Spring

7. COMPOSITE MATERIALS, FRP:
• A composite is usually made up of at least two materials out of which one is
the binding material, also called matrix and the other is the reinforcement
material .( fiber Kevlar and whiskers) . The advantage
of composite materials over conventional materials stem largely from
their higher specific strength, stiffness, strong load carrying capacity
fatigue characteristics, which enables structural design to be more
• Fiber-reinforced composite materials consist of ‘fibers’ of high strength and
modulus embedded in or bonded to a ‘matrix’ with distinct interface
(boundary) between them. In this form, both fibers and matrix retain their
physical and chemical identities, yet they produce a combination of
properties that cannot be achieved with either of the constituents acting
alone

8. COMPOSITE LEAF SPRING:

9. Literature Review:
• Priyanka Kothari " Leaf springs are one of the oldest suspension components
they are still frequently used, especially in commercial vehicles. The literature
has indicated a growing interest in the replacement of steel spring with
composite leaf spring. The suspension system in a vehicle significantly affects
the behavior of vehicle, i.e vibration characteristics including ride comfort,
stability etc. Leaf springs are commonly used in the vehicle suspension
system and are subjected to millions of varying stress cycles leading
to fatigue failure. A lot of research has been done for improving the
performance of leaf spring
• Erol Sancaktar (1999), in his work described the design and manufacture of a
functional composite leaf spring for solar powered light vehicle. The main
objective of this work was to provide and understanding of the manufacture,
use and capabilities of composite leaf spring. The material selected for the
fabrication of the initial design leaves consisted of a full thickness of
unidirectional E-glass fibers with two layers of bi-directional fabric on the outer
layers embedded in a vinyl ester resin matrix. The bi-directional fabric used to
prevent leaf deformation and subsequent failure in bending about its
longitudinal axis it was selected due to overall weight reduction of the vehicle
primarily considered

10. PROBLEM DEFINITION AND
METHODOLOGY
• There is currently much interest in deformation analysis of multiple
elastic-plastic bodies in contact. One such case is the design and
analysis of the automobile leaf springs, In order to accurately model
the deformations and vibrations of the leaf springs, nonlinear finite-
element procedures are need to be employed, with the advent of
development of the contact analysis, it is appropriate to apply the
contact analysis technique in the analysis of the leaf springs . Thus the
effect of the system with contact has to be studied. Methods for
modelling the contact and friction between the leaves of the spring
are to be developed.

11. PROJECT OVERVIEW:
• Various Design methods adopted leaf springs Regular design,3 layers, 5
Layers using CATIA software. Design of leaf spring completed based on ISO
standard drawing sheet.
• Stresses, deformations, strain, shear stress are calculated for four different
materials Steel, E GLASS EPOXY, GRAPHITE EPOXY, HYBRID
MATERIAL(EGLASS/GRAPHTIE) of leaf spring
• Leaf spring design imported in Ansys software for analysis purpose. Structural
analysis
• Perform the static analysis
• Consider the 7125N applied on leaf spring because of this working loading
conditions
• From these results, concluded the suitable leaf springs proposed under
conditions with 4 materials

12. MATERIAL
PROPERTIES
MATERIAL
PROPERTIES
Density
(kg/m3)
Possion’s
Ratio
(µ)
Young’s
Modulus
(GPa)
Ultimate
Tensile
strength
(MPa)
50Cr1v23 7850 0.3 210 2000
E –Glass epoxy 1900 0.2 230 900
Graphite epoxy 1605 0.3 80 1750

13. DESIGN CALCULATIONS:
Step (1): Material of leaf spring :
Material selected steel : 50 Cr 1 V 23
Composition of material :
0.45 % C
0.1-0.3 % Si
0.6-0.9% Mn
0.9-1.2% Cr
Step (2): Basic data of Ambassador leaf spring :
• Total length of the spring (Eye to Eye) = 1250 mm
• No. of full length leaves (nf) = 02
• No. of graduated leaves (ng) = 04
• Thickness of leaf ( t ) = 7 mm

14. • Width of the leaf spring ( b ) = 60 mm
• Total load = 2850 Kg
• BHN = 500 – 580 HB with hardened and tempered
Step (3): Basic requirement of load :
• Maximum capacity = 2850 Kg
= 2850 x 10
= 28500 N
• Ambassador is equipped with 4 nos. of semi elliptical leaf spring,
So load acting on the leaf spring assembly = 28500/4
= 7125 N
Step (4): Calculation of the load and effective length of leaf spring :
• Consider the leaf spring is cantilever beam. So the load acting on the each assembly
of the leaf spring is acted on the two ends of the leaf spring. Load acted on the leaf
spring is divided by the two because of consideration of the cantilever beam
2 W = 7125 N
W = 7125/2
W = 3562.5 N

15. • For support and clamping of the leaf spring the “U” bolt is use and the distance between
the “U” bolt is 110 mm. This is considered as an unbent portion of the leaf spring.
Ineffective length of the leaf spring is as under :
l = 110.00 mm
Effective Length of the spring,
2 × L = 2 × L1 − 1
2 × L = 1250 −
2
3
(110)
2 × L = 1176.67
L =
1176.67
2
L = 588.34

16. Step (5): Calculation of the pin of the leaf spring is as under :
Allowable bearing pressure of the eye [20] ( pb ) = 8 N/ mm2
Take length of the eye (l1 ) = 60 mm.
Load acting on the eye are as under:
𝑊 = 𝑙 × 𝑙1 × 𝑝𝑏
𝑑 =
𝑊
𝑙1 × 𝑝𝑏
𝑑 =
3562.5
60 × 8
𝑑 = 7.42𝑚𝑚
𝑑 = 8𝑚𝑚
Considering factor of safety is 2.
Calculation of the bending moment of the pin is as under :
Length of the pin = Length of the eye + (2 Clearance)

17. (Take the clearance 2.50 mm per side [20])
𝑙𝑝 = 60 + 2 × 2.50
𝑙𝑝 = 65𝑚𝑚
Step(6): Calculations of the length of leaves are as under :
Ineffective length of the leaf spring (l) = 110 mm
Length of the leaf spring is as under:
Length of the smallest leaf =
Effective length
n−1
+
2
3
(ineffective length)
= (
2×L
n−1
× 1) +
2
3
(ineffective length)
= (
2 × 588.34
6 − 1
× 1) + 73.33
= 308.66mm

18. • Length of the 2nd leaf=
Effective length
n−1
+
2
3
(ineffectiv length)
= (
2×L
n−1
× 2) +
2
3
(ineffectiv length)
= (
2 × 588.34
6 − 1
× 2) + 73.33
= 544mm
• Length of the 3rd leaf= (
2×L
n−1
× 3) +
2
3
(ineffectiv length)
= (
2 × 588.34
6 − 1
× 3) + 73.33
= 779.34mm

19. • Length of the 4th leaf = (
2×L
n−1
× 4) +
2
3
(ineffectiv length)
= (
2 × 588.34
6 − 1
× 4) + 73.33
= 1014.67mm
• Length of the 5th leaf
2×L
n−1
× 5) +
2
3
(ineffectiv length)
= (
2 × 588.34
6 − 1
× 5) + 73.33
= 1250mm
 But 5th and 6th leaves are full length leaves and 6th leaf is known as a master leaf.
 Length of the master leaf calculated is as under:
Length of master leaf = 2 × L1 × π d + t
= 1250 + π 30 + 7 × 2
= 1482.48

20. Step (8): Calculation of radius is as under :
R = Radius to which the leaves should be initially bent
y = Camber of the spring
y(2 × R − y) = (L1)2
176.26(2 × R − 176.26) = (625)2
R = 1196.22mm

21. Modelling Using CATIA:
• CATIA (Computer Aided Three-Dimensional Interactive Application) started
as an in-house development in 1977 by French aircraft manufacturer Avions
Marcel Dassault, at that time customer of the CAD/CAM CAD software to
develop Dassault's Mirage fighter jet.
• CATIA provides a wide range of applications for tooling design, for both
generic tooling and mold & die. A rich catalog of industry-standard
components is provided to automate tooling definition. Specific tools are
also provided to address the needs of mold tool injection designers.

22. DESIGN PROCEDURE IN CATIA
• Create the two circles(eye) a in sketcher workbench as per above
dimensions 625mm from absolute axis after create the leaf circle
create the offset distance is 6mm after go to the part design work
bench apply pad 60mm width as shown below figure.
EACH LEAF THICK NESS IS 6MM

24. ANALYSIS PROCEDURE IN ANSYS:
• Designed component in catia workbench after imported into
ansys workbench now select the steady state thermal analysis .
• 1.ENGINEEERING MATERIALS (MATERIAL PROPERTIES).
• 2.CREATE OR IMPORT GEOMENTRY.
• 3.MODEL(APPLY MESHING).
• 4.SET UP(BOUNDARY CONDITIONS)
• 5.SOLUTION
• 6.RESULTS

25. STATIC STRUCTURAL ANALYSIS:
• The static structural analysis calculates the stresses,
displacements, shear stress and forces in structures caused
by a load that does not induce significant inertia and
damping effects. Steady loading and response conditions
are assumed; that the loads and the structure’s response
are assumed to change slowly with respect to time. A static
structural load can be performed using the ANSYS
WORKBENCH solver. The types of loading that can be
applied in a static analysis include:

26. Work Bench Overview Of Ansys

27. Here consider the 3 designs regular method and 3 layers and 5 layer s
with various materials they are E glass epoxy , graphite epoxy, steel,
hybrid ( E glass and graphite epoxy) material
Boundary condition fixed at two hinges and apply load 7125 N in
centre of the leaf spring as shown below figues
MESH AND BOUNDARY CONDITIONS
MESHING
NODES 3597 ;ELEMENTS 350
BOUNDARY CONDITIONS

28. RESULT AND DISCUSSION
STATIC ANALYSIS RESULTS:
This analysis is performed to find Structural parameters such as Stresses,
Deformation, Shear stress, strain Here we observed results on three
materials namely E glass epoxy , graphite epoxy, steel.
50Cr1V23 Steel Material:
Von-misses stress Total deformation

29. Strain of 50Cr1V23 Steel
Material
Shear stress of Graphite
epoxy Material

30. E GLASS EPOXY MATERIAL
Strain of E GLASS e epoxy Material
Shear stress of E GLASS e epoxy Material
Total deformation of E GLASS epoxy Material
Von-misses stress of E GLASS epoxy
Material

31. GRAPHITE EPOXY MATERIAL:

32. RESULT AND DISCUSSION
This graph shows the different maximum stress values in different
materials, e glass epoxy 42.793 Mpa material has least stress value
compared to another materials as shown in the graph.

33. This graph shows the Different maximum Deformation values in
different materials, e glass epoxy 0.193mm material has least
deformation value compared to another materials as shown in the
graph
Deformation Graph

34. SHEAR STRESS GRAPH:
This graph shows the Different maximum Shear stress values in
different materials, graphite epoxy 0.83 Mpa material has Shear
value lesser compared to another materials as shown in the graph.

35. STRAIN GRAPH:
This graph shows the Different maximum Strain values in different
materials, e glass epoxy 0.0001901 material has Strain value
compared to another materials as shown in the graph.

36. Advantages of Composite Leaf Spring:
• Minimum wear and tear of body parts and tyres due to delicate
tendency of absorbing shocks , jerks and vibrations.
• Softer ride, lower noise level, excellent stability due to better damping
characteristics.
• Excellent corrosion resistance to atmospheric pollutants.
• Five times stronger than conventional leaf spring.
• Increase in fuel efficiency due to better aerodynamics and around 60%
weight reduction.
• Fully interchangeable into conventional leaf spring without any
modifications.

37. Demerits Of Conventional Leaf Spring:
• They have less specific modulus and strength.
• Increased Weight.
• Conventional leaf springs are usually manufactured and assembled by using
number of leaves made of steel and hence weight is more.
• Its corrosion resistance is less when compared to composite leaf springs.
• Steel leaf springs have less damping.

38. APPLICATIONS OF LEAF SPRING:
To cushion, absorb or control energy due to either shock or
vibration as in car springs, railway buffers, air-craft landing
gears, shock absorbers and vibration dampers.
To apply forces, as in brakes, clutches and spring loaded valves.
To control motion by maintaining contact between two elements
as in cams and followers.
To measure forces, as in spring balances and engine indicators.
To store energy, as in watches, toys, etc.

39. Conclusion:
• As automobile world demands research of reducing weight and
increasing strength of products, composite material should be up
to the mark of satisfying these demands. As leaf spring contributes
considerable amount of weight to the vehicle and needs to be
strong enough.
• Deflection of e glass epoxy are 0.193 mm. e glass epoxy von- misses
stress are 42.793MPa and also the Shear stress leaf spring0.83,
respectively. E glass epoxy the Strain are 0.0001901
• A comparative study has been made between e glass 50cr1V23 Steel
and graphite leaf spring with respect to strength and weight. Here
find out deformations at different frequencies are obtained by
analyzing the Leaf spring with by using e glass epoxy material,
graphite epoxy and 50Cr1v23 Steel Material finally e glass epoxy
material is the better material ,leaf spring reduces the weight by
74.54% e glass epoxy over steel and graphite epoxy leaf spring,
finally concluded the e glass epoxy because of high strength low
weight and cost.

40. Future Scope
• Transient analysis of leaf spring
• Manufacturing of composite leaf spring.
• Experimental results for composite leaf spring.
• Residual stress calculation using FEA

41. References:
• Design and analysis of composite Leaf Spring for light Weight Vehicle
D. Lydia Mahanthi, C. Venkata Siva Murali
PG. student, Mechanical Department, Sri Padmavathi Mahila Visvavidyalayam,
Tirupati, India
Assistant Professor, Mechanical Department, Sri Padmavathi Mahila
Visvavidyalayam, Tirupati, India
• Design of Leaf Spring by NPTEL(National Programme Technology
Enhanced Learning)
• Design, Analysis and Experimental Testing of Composite Leaf Spring for
Application in Electric Vehicle
Mayur D. Teli, Umesh S. Chavan, Haribhau G. Phakatkar

42. Thank You