Static and Dynamic Analysis of Leaf Spring (TATA ACE)

IJSTE - International Journal of Science Technology & Engineering | Volume 1 | Issue 11 | May 2015 ISSN (online): 2349-784X

All rights reserved by www.ijste.org

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Static and Dynamic Analysis of Automobile Leaf

Spring (TATA ACE)

Trivedi Achyut V. Prof. R.M. Bhoraniya

M. Tech CAD/CAM Professor

Department of Mechanical Engineering Department of Mechanical Engineering

Marwadi Education Foundations Group of Institution Rajkot-360007,India

Marwadi Education Foundations Group of Institution Rajkot-360007,India

Abstract

The Automobile firm has shown greater interest for replacement of conventional steel leaf spring with that of composite leaf

spring, as the composite material has high strength to weight ratio, good corrosion resistance. The objective of this work is to

compare the load enhancing capacity, and weight savings of composite leaf spring with respect to conventional steel leaf spring.

The dimensions of an existing conventional steel leaf spring of a Light design calculations. Static Analysis of 3-D model of

conventional leaf spring is performed using analysis commercial software. And that dimensions are used for composite multi

leaf spring as well by taking composites as carbon/Epoxy and Graphite/Epoxy . The constraints are stress and deformation and

weight of composite leaf spring with respect to conventional steel leaf spring. For static condition static analysis done and for

real time problem dynamic analysis work present here.

Keywords: Leaf Spring, Dynamic Analysis

________________________________________________________________________________________________________

I. INTRODUCTION

Insight to take maximum advantages of natural resources and also to economize the energy, weight reduction has been the main

area of focus for an automobile manufacturer in the today scenario. Initially Weight can be reducing by the introduction of better

material, doing design optimization and by applying better manufacturing processes. The suspension system element termed as

leaf spring is one of the critical part for weight reduction in automobile as it takes ten to twenty percent of the unstrung weight.

That can been helpful to achieve the vehicle been improved riding qualities. As we know that springs, are mainly designed to

absorb (catch-up) and store energy and then when it need it can release that energy. In that, the strain energy (for spring) of the

material can become a major part in designing the springs.

Main proposes for the introduction of composite materials mainly was made it possible for reduction into the weight of the

leaf spring, without any reduction on load carrying capacity and stiffness. As we all know that the composite materials having

more elastic (strain) energy storage capacity and high strength-to-weight ratio with respect to those of steel.

Multi-leaf springs are more used for automobile and sometime for rail road suspensions. It has a geometry which consist a

series of flat plates, usually having a semi- elliptical shape as shown in fig. 1.1. As shown in figure the leaves are held together

with the help of two U-bolts and also centre clip. Also in that Rebound clips are provided to keep the leaves in alignment and

save from lateral shifting of the plates during the working condition. The leaf having maximum length, called the master leaf,

master leaf is bent at both ends to form the spring eye part.

Fig. 1: Leaf Spring

At the center position, the spring is fixed to the main axle (front or rear) of the car. Mainly Multi- leaf springs are provided

with one or mostly with two extra full length leaves in addition to the master leaf. These extra full-length leaves can be stacked

between the master leaf having maximum length and the graduated-length leaves. The extra full-length are provided to support

the transverse shear force acting on the component.

Static and Dynamic Analysis of Automobile Leaf Spring (TATA ACE) (IJSTE/ Volume 1 / Issue 11 / 024)


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II. WORKING PRINCIPLE OF LEAF SPRING

The suspension system having main element termed as leaf spring is one of the potential and very critical term for weight

reduction in automobile industries as its having a ten to twenty percent of the unsprung weight. By introducing composites, it can

helpful for design a better suspension system having a better ride quality but the condition is it must be achieved without much

increase cost and also decrease quality and reliability. In the design of springs, strain energy becomes the major factor. The

relationship of the specific strain energy can be expressed as

U=2/Eeq. (1.1) Where = strength, =density E =Youngs Modulus of the spring material

It can be noted that material which is having a lower modulus and also having a lower density will have a greater specific

strain energy capacity. So the introduction of composite materials can made it possible to reduce the weight of the leaf spring

without any reduction into the load carrying capacity and stiffness. A Composite mainly is any materials that have been

physically assembled to form one single bulk without physical blending to foam a homogeneous material. The resulting

material would still have components identifiable as the constituent of the different materials. One of the advantages of

composite is that two or more materials could be combined to take advantage of the good characteristics of each.

Fig. 1.2 shows an Arrangement of leaf spring into a car Model a spring eye section is used to attach the front end of semi-

elliptic shape leaf spring to the chassis frame, and a free end having a bracket constraining vertical motion to attach the back end

of semi-elliptic leaf spring to the chassis frame.

Fig. 2: Arrangement of Leaf Spring in Car Model

III. SPECIFICATION OF LEAF SPRING

Forces acting on leaf spring are as shown in fig. Main forces acting on leaf spring are as follow but in this analysis only vertical

loading condition is considered. Forces acting on leaf spring:

Vertical loading (Fv)

Side load (Fs)

Longitudinal load (Ft)

Twisting torque (Tt)

Windup torque (Tw)

Fig. 3: Load Acting on Leaf Spring



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Assumptions for Analysis: A.

Automobile is assumed to be stationary.

There are 2Semi-elliptic leaf spring, one at front and one at rear axle. And for Only vertical loading.

Static analysis is carried out for rear single semi-elliptic leaf spring.

IV. ANALYSIS OF LEAF SPRING

The leaf spring having specification as shown in table 1 initially static analysis done on leaf spring by considering leaf spring as

a simple supported beam and design constraints are stress and deformation. The result as show in figure . analysis done on ansys

and for validation mathematical calculation done. For real time problem the dynamic (Modal analysis ) considered for time

period of 5s. the purpose of this work is to avoid the resonance occur with new leaf spring. Table 1

Specification of TATA ACE Leaf Spring

Sr.no Design parameter Value

1 Total length of spring(L) 930mm

2 Length of spring from eye to eye 754mmm

3 Thickness(t) 8mm

4 Width of leaf spring(b) 60mm 1) Specification of TATA ACE [15]

Weight of vehicle = 500 Kg

Maximum load carrying capacity = 325 Kg

Total weight = 500+325

So , total weight = 825 Kg

Static load apply on vehicle = 825*9.81 N

So , static load apply on vehicle 8000 N (approx.)

At every wheel load = 2000 N and same as reaction force = 4000 N at downward point. Table 2

Material Properties of Conventional Material

Material selected[10] 65si7

Youngs Modulus,(E) 2.1*105 N/mm2

Poissons Ratio 0.266

Tensile Yield strength 250 MPa

Density 7850 Kg/m3

Behavior Isotropic

Fig. 4: Model of Leaf Spring (TATA ACE)



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Fig. 5: Stress in Conventional Material

Fig. 6: Deflection in Conventional Material

Table 3 Composites Material Properties

Material selected[15] E-Poxy

Exx 34000 MPa

Eyy 6530 MPa

Ezz 6530 MPa

Poisons ratio along XY 0.217

Poisons ratio along YZ 0.366

Poisons ratio along XZ 0.217

Gxy 2433 MPa

Gyz 1698 MPa

Gxz 2433 MPa

Density of material 2.6*1000 kg/mm3

Behavior orthotropic

Fig. 7: Stress in Composites Material



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Fig. 8: Deflection in Composites Material

1) Mathematically Validation:

By considering beam equation[16]:

As Maximum deflection can be given by: (X=L)

Max. deflection =

Max. deflection = 0.06459 m

Table 4 Analytical and Ansys Result Comparison

Material Deformation (m) Error (%)

Conventional steel Analytical Simulation

0.06459 0.05616 2.1

Table 5 Analytical and Ansys Result Comparison

Material Stress (Pa) Deformation (m) Mass (Kg)

65si7 5.8739e8 .006 5.45

E-Poxy 4.74e8 0.05616 1.8

Fig. 7: Frequency and Deformation at Mode 5

Fig. 8: Modal Analysis at 5s for Forced Vibration



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Table 6 Comparing Frequencies for Resonance Effect

Sr. no

For max modal shape at 5s time

Frequency(Hz) Natural frequency(Hz)

655 598

V. CONCLUSION

In this research we can conclude that with respect to conventional steel leaf spring composites having high strength to weight

ration. Also composites having nearly 400% less weight than conventional steel leaf spring. And also from Modal analysis we

can conclude that composite leaf spring is safe as its not showing resonance effect so its safe in that manner.

REFERENCES

[1] Mahmood M. Shokrieh , Davood Rezaei Analysis and optimization of a composite leaf spring, Composites Research Laboratory, Department of Mechanical Engineering, Composite Structures 60 (2003) 317325

[2] B.Vijaya Lakshmi & I. Satyanarayan, Static and dynamic analysis on composite leaf spring in heavy vehicle , International Journal of Advanced Engineering Research and Studies ,Vol. 2, Issue Oct.-Dec.,2012, 80-84

[3] I.Rajendran ,& S.Vijayarangan , optimal design of a composite leaf spring using genetic algorithms, computers & structures 79(2002) 1121-1129

[4] M. Raghavedra,& Syed Altaf Hussain, Modeling and Analysis of Laminated Composite Leaf Spring under the Static Load Condition by using FEA International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.4, July-Aug. 2012, 1875-1879 ISSN: 2249-6645

[5] H.A.Al-Quereshi Automobile leaf spring from composite materials, journal of material processing technology, 118(2001), 58-61

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Static and Dynamic Analysis of Leaf Spring (TATA ACE)