my FEA project

7/31/2019 my FEA project

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Contents

CONTENTS

CHAPTER Page No.

ACKNOWLEDGEMENTi

SYNOPSIS..ii

LIST OF FIGURESiii

1. INTRODUCTION...1

1.1 Requirements of the leaf spring................................................................1

1.2 Glass fiber...2

1.3 Epoxy resin.....2

2. LITERATURE SURVEY...3

2.1 Need for current study...4

3. PROBLEM DEFINITION..5

4. OBJECTIVE.. 6

5. METHODOLOGY....................7

6. SYSTEM SPECIFICATIONS...8

6.1 Specification and material properties of steel leaf spring....8

6.2 Specification of material properties of composite leaf spring.8

7. EXPECTED DELIVERABLES.....9

7.1 Software used.....9

8. MODELING10

9. ANALYSIS..11

9.1 Stress distribution of steel leaf spring..........................................................11

9.2 Stress distribution of composite leaf spring.................................................11

10. CONCLUSION.....12

11. BIBLIOGRAPHY..13


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Synopsis

ii

SYNOPSIS

A steel spring used in the rear suspension system of light vehicles is analyzed

using ANSYS software. By using the finite element results, stresses and deflections are

verified. Using the results of the steel leaf spring, a composite leaf spring made up of

fiberglass with epoxy resin is designed and optimized using ANSYS software. The main

consideration is given to the geometry optimizitation of the leaf spring geometry. The

main objective is to compare the load carrying capacity, stiffness and weight reduction of

composite leaf spring with that of steel leaf spring. The results showed that an optimum

leaf spring width decreases hyperbolically and the thickness increases linearly from the

spring eyes towards the axle seat. Compared to the steel leaf spring, the optimizied

composite spring has stresses that are much lower and spring weight without eye unnits

nearly 80% lower.


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Introduction Chapter 1

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CHAPTER 1

INTRODUCTION

Leaf spring is made of steel that is mounted on the front and rear axle of a car. The

leaf spring absorbs the load acting on the vehicle. In steel leaf spring the weight is

comparatively more. Composite materials are now used extensively in the automotive

industry to take place of metal parts. In the present trends the weight reduction has been the

main focus of automobile manufacturers.

Less fuel consumption, less weight, effective utilization of natural resources is main

focus of automobile manufacturers in the present scenario. The above can be achieved byintroducing better design concept, better material and effective manufacturing process.

Steel leaf springs have many advantages such as good load carrying capacity. In

spite of its advantages, it stays back in low strength to weight ratio. It is reported that weight

reduction with adequate improvement of mechanical properties has made composites as a

viable replacement material for conventional steel.

In this work, the steel leaf spring is replaced with the composite leaf spring made of

glassfiber epoxy resin. The main consideration was given to the optimization of the leaf

spring geometry. The objective was to obtain a spring with minimum weight that is capableof carrying given static external forces by constraints limiting stresses and displacements.

1.1Requirements of the leaf spring: It should absorb more load.

It should have good rust resistance.

It should have high strength.

Light in weight.

Easy to manufacture in large quantity.

Low cost.


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Introduction Chapter 1

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1.2Glass fiber:The aim of fiber reinforced plastics is to combine the stiffness and strength of fibrous

material. This material has corrosion resistance, low density and mould ability. The majority

of reinforced plastics produced today are glass reinforced epoxy or polyester resins, both of

which are thermosetting.Glass fibers have also been used with phenolics, silicones, polystyrene and polyvinyl

chloride. Glass fibers are the obvious choice as reinforcing agents, principally because of

the relative ease with which high strengths can be obtained fiber a few microns in diameters.

1.3Epoxy resin:Epoxy resins are the most commonly used resins. They are low molecular weight

organic liquids containing epoxide groups. Epoxide has three members in its ring, 1oxygen

and 2 carbon atoms. The reactions of Epichlorohydrin with phenols or aromatic amines

make most epoxies. Hardeners, plasticizers and fillers are also added to produce epoxies

with a wide range of properties of viscosity, impact, degradation, etc.

Although epoxy is costlier than other polymer matrices, it is the most popular PMC

matrix. More than two thirds of the polymer matrices used in aerospace applications is

epoxy based.

The main reasons for epoxy being the most used polymer matrix materials are

Good compatibility with Glass fiber

High strength

Low viscosity and low flow rates, which allow good wetting of fibers and

misalignment of fibers during processing

Low shrink rates which reduce the tendency of gaining large shear stresses of the

bond between epoxy and its reinforcement.

Available in more than 20 grades to meet specific property and processing

requirements.


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Literature Survey Chapter 2

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beam component, along the fibre and the matrix direction, showing high data dispersion

in the normal direction.

2.1 Need for current study:

Extensive research has been performed in composites materials. Springs are crucial

suspension elements on cars, necessary to minimize the vertical vibrations, impacts and

bumps due to road irregularities and create a comfortable ride. Also to reduce the weight of

the vehicle this contributes fuel consumption. Generally more stresses will be acting on the

leaf spring, in order to reduce the stresses acting on the leaf spring stress analysis has to be

done. Here, leaf spring made of steel and composite materials are taken into consideration

and optimum leaf spring is chosen which reduces the stresses acting on it.


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Problem Definition Chapter 3

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CHAPTER 3

PROBLEM DEFINITION

The major problem in the leaf spring is that, stresses acting in it which causes vibration

to vehicle body, bumping due to road irregularities and vehicle will wear-out soon due to

vibrations. In order to reduce the vibration in the vehicle body, the stresses acting on the leaf

spring has to be reduced. To reduce the stresses acting on the leaf spring, optimum leaf spring

has to be chosen. In this study to choose the optimum leaf spring stress analysis has to be

carried for steel leaf spring and composite leaf spring made from fibreglass with epoxy resin.


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Objective Chapter 4

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CHAPTER 4

OBJECTIVE

The purpose of the present investigation is to reduce the stress acting in the leaf spring in

order to reduce the vibration of vehicle. It can be achieved by choosing suitable composite

materials.

The main objectives of this work are;

To do Finite Element Modeling of stress acting on the steel leaf spring and composite

leaf spring.

To choose the optimum leaf spring which have lower stress.


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Methodology Chapter 5

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CHAPTER 5

METHODOLOGY

In order to obtain the desired objective, the present investigation has been planned

in the following sequence:

(i) Identification of problem in using steel leaf spring.

(ii) Choosing suitable composite material to overcome the problems in the current

material.

(iii) Developing CAD model for steel leaf spring and for composite leaf spring with

the optimal geometry.

(iv) Import the CAD models in ANSYS software in .IGES format.

(v) Provide suitable material properties for steel and composite leaf spring.

(vi) Choose mesh element and meshing is carried out.

(vii) Applying boundary conditions.

(viii) Appling load and solve.

(ix) Finally result correlation between steel and composite leaf spring should be

done.


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System Specifications Chapter 6

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CHAPTER 6

SYSTEM SPECIFICATIONS

Specifications and material properties of steel and composite leaf springs are

collected from various journals and books.

6.1 Specification and material properties of steel leaf spring:

Length =1245mm

Thickness = 7mm

Front half =559mm

Arc Height at axle seat =120.4mm

Spring rate =20.76N/mm

Normal static loading =2500N

Full bump loading =4660N

Available space for spring width =50mm

Weight =9.2kg

Youngs modulus = 210Gpa

Poisson ratio = 0.3

6.2 Specification of material properties of composite leaf spring:

Length =1245mm

Thickness =10mm

Front half =559mm

Arc Height at axle seat =120.4mm

Spring rate =20.76N/mm

Normal static loading =2500N

Full bump loading =4660N

Available space for spring width =30mm

Weight =2.3kg

Youngs modulus = 38.6Gpa

Poisson ratio = 0.26


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Expected deliverable Chapter 7

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CHAPTER 7

EXPECTED DELIVERABLE

As a result of this work, stress distribution on the leaf spring can be calculated for

both steel and composite leaf spring.

Also, optimum spring can choose by using these results.

7.1 Software used:

Pro/E for modeling.

ANSYS for analysis.


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Modeling Chapter 8

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CHAPTER 8

MODELING

Fig. 1 3D model of leaf spring

Fig. 2 Finite Element Mesh of leaf spring


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Analysis Chapter 9

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CHAPTER 9

ANALYSIS

Fig. 3 Stress distribution of steel leaf spring

Fig. 4 Stress distribution of composite leaf spring


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Conclusion Chapter 10

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CHAPTER 10

CONCLUSION

A steel leaf spring used in the rear suspension of light passenger cars was analyzed

by analytical and finite element methods. The experimental results verified the finite element

solutions. The steel leaf spring was replaced with an optimized composite one. Main

consideration was given to the optimization of the leaf spring geometry.

The results showed that the optimum spring width decreases hyperbolically and the

thickness increases linearly from spring eye towards the axle seat. The stresses in the

composite leaf spring are much lower than that of the steel spring. Compared to the steel

leaf spring (9.2 kg) the optimized composite leaf spring without eye units weights nearly

80% less than the steel spring.


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Bibliography Chapter 11

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CHAPTER 11

BIBLIOGRAPHY

1. Mahmood M. Shokrieh, Davood Rezaei, 2003, Analysis and optimization of a composite

leaf spring, Journal of composite structures, vol. 60, p.317-325.

2. Tsai SW, Hahn HT, 1980 Introduction to composite materials, Technomic Publishing.

3. M. Senthil Kumar, S.Vijayarangan, 2006, Static analysis and fatigue life prediction of

steel and composite leaf spring for light passenger vehicles Journal of Scientific &

Industrial Research.

4. K. Kaw, Mechanics of composite materials, CRC Publication.

5. www.sciencedirect.com.

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my FEA project