Design Analysis and Experimental investigation of Composite … · 2017. 7. 12. · 4) Static analysis of standard Steel leaf spring and composite E-glass/Epoxy leaf spring using

DOI: 10.23883/IJRTER.2017.3234.XGEI5 350

Design Analysis and Experimental investigation of Composite Mono

Leaf spring

Prof. Gayatri J. Abhyankar1, Vaibhav Holkar

2, Bhiva Malkar

3, Ganesh Sutar

4, Rajesh teli

5

1,2,3,4,5Professor of mechanical engineering, Finolex Academy of Management and Technology,

Ratnagiri

Abstract: Reducing weight while increasing or maintaining strength of products is getting to be

highly important research issue in this modern world. Composite materials are one of the material

families which are attracting researchers and being solutions of such issue. The Automobile Industry

has great interest for replacement of steel leaf spring with that of composite leaf spring, since the

composite materials has high strength to weight ratio, good corrosion resistance. The material

selected was glass fiber reinforced polymer (E-glass/epoxy). The design parameters were selected

and analyzed with the objective of minimizing weight of the composite leaf spring as compared to

the steel leaf spring.

The work also gives focus on the application of FEA concept to compare two materials for leaf

spring and propose the one having higher strength to weight ratio. Two materials used for

comparison are; conventional steel and composite E-Glass/Epoxy. The deflection and bending

stresses induced in the two leaf springs are compared. The solid modelling of leaf spring is done in

SOLIDWORKS and analyses using ANSYS (WORKBENCH) 16.2. In addition to this

experimentation is done on the UTM.

Keywords—E-Glass/Epoxy, Leaf spring, SOLIDWORKS, Ansys 16.2 (Workbench).

I. INTRODUCTION Suspension system of any vehicles contains leaf spring to absorb jolts. Leaf springs are mainly used

in suspension systems to absorb shock loads in automobiles like light motor vehicles, heavy duty

trucks and in rail systems. It carries lateral loads, brake torque, driving torque in addition to shock

absorbing. The advantage of leaf spring over helical spring is that the ends of the spring may be

guided along a definite path as it deflects to act as a structural member in addition to energy

absorbing device .The vehicles must have a good suspension system that can deliver a good ride and

good human comfort. It is observed that the failure of steel leaf springs is usually catastrophic.

According to studies made for leaf spring the for weight reduction in automobiles as it leads to the

reduction of un-sprung weight of automobile. The elements whose weight is not transmitted to the

suspension spring are called the unsprung elements of the automobile. This includes wheel assembly,

axles, and part of the weight of suspension spring and shock absorbers. The leaf spring accounts for

10-20% 0f the un-sprung weight. Material with maximum strength and minimum modulus of

elasticity in the longitudinal direction is the most suitable material.

To meet the need of natural resources conservation, automobile manufacturers are attempting to

reduce the weight of vehicles in recent years. Weight reduction can be achieved primarily by the

introduction of better material, design optimization and better manufacturing processes. In order to

reduce the accidents, arising out of such failures conventional steel leaf spring can be replaced with

gradually failing composite leaf springs. By doing this, the weight of the vehicle may also be

reduced while maintaining the strength of the leaf spring. A composite material is nothing but

International Journal of Recent Trends in Engineering & Research (IJRTER)

Volume 03, Issue 05; May - 2017 [ISSN: 2455-1457]

permutation of two materials that produce an effect so that the combination produces combined

properties that are different from any of those of its constituents. This is done purposefully in today’s

scenario to achieve different design, manufacturing as well as service advantages of product. In this

paper leaf spring is representative of those products, for which automobile manufacturers are

working to get best composite material that meets the current requirement of strength and weight

reduction in one, to replace the existing steel leaf spring. The objective of the paper is to design leaf

springs for deflection and bending stress made of steel and composite material.

II. OBJECTIVE

In order to safeguard natural resources and economize energy, weight reduction has been the main

focus of automobile manufacturers in the present development. The introduction of better material,

design optimization and better manufacturing processes can cause weight reduction in vehicle. The

leaf spring is one of the potential items for weight reduction in automobile as it accounts for ten to

twenty percent of the un-sprung weight.

1) To achieve substantial weight reduction in the suspension system.

2) Comparison of the results of standard Steel leaf spring and composite leaf spring.

3) Validation of results by theoretical calculations and experimentation on UTM.

4) Static analysis of standard Steel leaf spring and composite E-glass/Epoxy leaf spring using

FEA. Finding out the deflection and bending stress for the same.

III. DESIGN OF LEAF SPRING Mahindra Bolero Pick up FB PS specifications:

Kerb weight = 1725 kg

Load carrying capacity = 1250 Kg

Gross weight of vehicle (m) = 1725+1250

=2975 Kg

Taking factor of safety (FOS) = 1.3

Acceleration due to gravity (a) = 9.81 m/s^2

Therefore,

Total weight W = m × a × FOS

=2975×9.81×1.3

=37940.175 N

=

= 9485.04 N

Fig 1. Cantilever leaf

The table I below shows the specifications of conventional leaf spring for selected vehicle:

Parameter Value

Length of the master leaf spring (2L) 900 mm

Mass of the master leaf spring 2.0875 Kg

Thickness (t) 8 mm

Width (b) 60 mm


For steel leaf spring

The mechanical Properties of conventional steel are as shown in table II below;

Mech anical Properties of EN 47 Steel

Properties Values

Young’s modulus 200000

Tensile strength 650

Elongation 8-

Fatigue 275

Yield strength 350

Density 7700

Deflection of the leaf spring is given by,

= -------------

Bending stress in the leaf spring is given by,

Let, W-Load on vehicle (N) L- Length of spring (mm) n

E-Young Modulus (MPa) b- Width of leaf spring (mm) t

(mm) σ- Bending Stress (MPa)

For manufacturing of composite leaf spring, we selected E glass/Epoxy composite material the

properties of the material are mentione

Sr.no.

1 Tensile modulus along X

2 Tensile modulus along Y

3 Tensile modulus along Z

4 Tensile strength of the material

5 Compressive strength of the material

6 Shear modulus (Gxy)

7 Shear modulus (Gyz)

8 Shear modulus (Gzx)

9 Poisson ratio along XY

10 Poisson ratio along YZ

11 Poisson ratio along ZX

12 Mass density of the material (

13 Flexural modulus of the material

14 Flexural strength of the material

By using the equation I and II the maximum deflection and maximum stress for steel leaf are

calculated and using these values thickness of the composite leaf is calculated by keeping width

constant and select the maximum thickness.

The values are,

E= 34000 N/mm^2

IV.

Finite element analysis is a computer based analysis technique for calculating the strength and

behavior of structures. In the FEM the structure is represented as finite

joined at particular points which are called as nodes. The FEA is used to calculate the deflection,


Volume 03, Issue 05; May - 2017 [ISSN: 2455

The mechanical Properties of conventional steel are as shown in table II below;

anical Properties of EN 47 Steel

Values Unit

200000 Mpa

650-880 Mpa

-25 %

275 Mpa

350-550 Mpa

7700 Kg/m^3

Deflection of the leaf spring is given by,

-------------I

Bending stress in the leaf spring is given by,

σ = -------------------II

Length of spring (mm) n- No. of spring

Width of leaf spring (mm) t- Thickness (mm) δ- Deflection of spring


properties of the material are mentioned in table below in table. [1]

Properties Value

Tensile modulus along X-direction (Ex) 34000 MPa

Tensile modulus along Y-direction (Ey) 6530 MPa

Tensile modulus along Z-direction (Ez) 6530 MPa

Tensile strength of the material 900 MPa

Compressive strength of the material 450 MPa

Shear modulus (Gxy) 2433 MPa

Shear modulus (Gyz) 1698 MPa

Shear modulus (Gzx) 2433 MPa

Poisson ratio along XY-direction(μxy) 0.217

Poisson ratio along YZ-direction (μyz) 0.366

Poisson ratio along ZX-direction (μzx) 0.217

Mass density of the material (ρ) 2.6*10^6 kg/mm3

Flexural modulus of the material 40000

Flexural strength of the material 1200



constant and select the maximum thickness.

E= 34000 N/mm^2 t = 15mm

FINITE ELEMENT ANALYSIS


behavior of structures. In the FEM the structure is represented as finite elements. These elements are



[ISSN: 2455-1457]

Deflection of spring





elements. These elements are




@IJRTER-2017, All Rights Reserved 353

stresses, strains temperature, buckling behavior of the member. In our project FEA is carried out by

using the ANSYS 16.2. Initially we don’t know the displacement and other quantities like strains,

stresses which are then calculated from nodal displacement.

Finite Element Analysis is a simulation technique which evaluates the behavior of components,

equipment and structures for various loading conditions including applied forces, pressures and

temperatures. Thus a complex engineering problem with non-standard shape and geometry can be

solved using finite element analysis where a closed form solution is not available. The finite element

analysis methods provide results of stress distribution, displacements and reaction loads at supports

etc. for the model.

Static analysis: A static analysis is used to determine the displacements, stresses, strains and forces in structures or

components caused by loads that do not induce significant inertia and damping effects. A static

analysis can however include steady inertia loads such as gravity, spinning and time varying loads.

In static analysis loading and response conditions are assumed, that is the loads and the structure

responses are assumed to vary slowly with respect to time. The kinds of loading that can be applied

in static analysis includes externally applied forces, moments and pressures, steady state inertial

forces such as gravity and spinning Imposed non-zero displacements. If the stress values obtained in

this analysis crosses the allowable values it will result in the failure of the structure in the static

condition itself. To avoid such a failure, this analysis is necessary.

Stepwise procedure for the static analysis of the leaf spring: 1) Prepare a geometric model of leaf spring by using solid works or other modelling software as

per the designed dimension. This geometric model is save in step file format.

2) Open the ANSYS Workbench 16.2, select static structural ANSYS system and drag into the

work place.

3) Update engineering data. For composite leaf spring, add the new material as E-glass fiber

with its mechanical properties.

4) Import geometry and slice is into two parts and supress the left half section.

5) Modelling : a) Meshing

b) Application of fixed support and force.

6) Solve.

7) Get the result.

The FEA of the leaf spring of both the materials are carried out and obtained results for deformation

and Equivalent von misses stresses in the leaf spring for different loads. The fig. shows the results

for deformation and Equivalent von misses stresses in both conventional and composite leaf springs.

The results are for design load i.e. 9485 N




Fig 2. Deformation in steel leaf spring Fig 3. Equivalent (von-mises) stress in steel leaf

Spring

Fig 4. Deformation in E-glass fiber leaf spring Fig 5. Equivalent (von mises) stress in E-glass

fiber leaf spring

V. EXPERIMENTATION

The composite leaf springs are tested by using the UTM. The spring to be tested is examined for any

defects like cracks, surface abnormalities, etc. The spring is loaded from zero to the prescribed

maximum deflection and back to zero. The load is applied at the centre of spring; the vertical

deflection of the spring centre is recorded in the load interval of 1000 N. The supports are given at

the both end of using fixtures and the deflection of the spring centre is recorded.



Experimental Procedure 1. The spring is loaded from zero to the prescribed maximum deflection and back to zero.

2. The load is applied at the center of spring.

3. In the testing, firstly move the plunger up to desired height so that we can fix the fixture and

leaf spring for test.

4. Fix the position of fixture.

5. On the fixture place the specimen.

6. Set the universal testing machine.

7. Apply the load gradually from 0 KN upto the fracture occurs.

8. The vertical deflection of the spring Centre is recorded simultaneously

9. The results are obtained in the form of graph of Load Vs Deflection.

Test specimen before testing and the cracks occurred in the test specimen after the testing are shown

below:

Fig 6. Test specimen before testing

Fig 7. Crack at the center of leaf Fig 8. Crack at end of leaf




VI. RESULT AND DISCUSSION

Percentage mass saving: The table shows the comparison between the mass of the steel Leaf spring and composite mono-leaf

spring.

Table 1: % Mass saving

1. Mass of the steel leaf spring 2.0875 Kg

2. Mass of the composite leaf spring 1.230 Kg

3. Percentage saving in mass 41.07 %

Above table shows that by using composite mono leaf spring 41.04% saving in mass is achieved.

Theoretical results: The theoretical values of the deflection and the stresses for steel leaf spring and E-glass fibre mono

leaf spring for the loads from 1000N to 10000N are tabulated in the table given below:

Table 2: Theoretical results for deflection and stress

Load (N)

Deflection (mm) Max. Stress (N/mm^2)

For EN47 steel

For E glass

Fibre

For EN47 steel

For E glass

Fibre

1000 59.32 52.94 703.125 200

2000 118.65 105.88 1406.25 400

3000 177.97 158.82 2109.37 600

4000 237.30 211.76 2812.5 800

5000 296.63 264.76 3515.65 1000

6000 355.95 317.64 4218.75 1200

7000 415.283 370.58 4921.87 1400

8000 474.63 423.52 5625 1600

9000 533.93 476.47 6328.12 1800

10000 593.26 529.41 7031.25 2000

The results obtained by theoretical calculation are represented on graphs as follows:

Plot of Load Vs Deflection (theoretical results) plot of Load Vs Max. stress (theoretical results)




FEA results: Similarly the values of the deflection and maximum stresses for the steel leaf and composite mono

leaf spring obtained from the FEA analysis are tabulated in the table given below.

Table 3: ANSYS results for deflection and stress

Load

(N)

Deflection (mm) Max. Stress (N/mm^2)

For EN47 steel

For E glass

Fibre

For EN47 steel

For E glass

Fibre

1000 64.56 9.89 684 189.69

2000 129.14 19.67 1368 378.35

3000 193.7 29.67 2052 569.07

4000 258.27 39.53 2736 756.7

5000 322.84 49.95 3420 948.45

6000 387.41 59.29 4104 1135

7000 451.98 69.23 4788 1327

8000 516.55 79.06 5472 1513

9000 581.11 89.01 6156 1707.2

10000 645.68 98.09 6840 1891.17

The results obtained from the analysis of the leaf spring are represented on graphs as follows:

Plot of Load Vs Deflection (ANSYS results) Plot of Load Vs Max stress (ANSYS results)

Experimentation result:

The composite mono leaf spring is tested on the UTM, the results are obtained in the form of graph

of Load vs displacement.




Plot of Load Vs Cross head travel

VII. 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, a single E-Glass/Epoxy

composite leaf spring is designed and analyzed following the design rules of composite materials.

� The mass of the Composite mono-leaf spring is reduced by 41.07%.

� From static analysis of standard steel leaf spring and composite E-glass fiber mono-leaf

spring using FEA, we found that deflection and max. stress in composite mono leaf spring is lesser

than conventional leaf spring hence conventional leaf spring can be easily replaced by composite

mono leaf spring.

� Experimentation shows that failure has occurred just before the designed load but by

increasing the thickness we can make it safe.

REFERENCES 1. Gulur Siddaramanna shiva shankar, Sambagam vijayarangan, (2006), “Mono Composite Leaf Spring for Light

Weight Vehicle – Design, End Joint Analysis and Testing.” Material Science, vol. 12, pp. 220-225

2. M.Venkatesan, D. Helmen Devaraj (2012), “Design and analysis of Composite leaf spring in light vehicle.”

International Journal of Modern Engineering Research (IJMER), vol. 3, pp. 213218

3. M. M. Patunkar, D. R. Dolas, (2011), “Modelling and Analysis of Composite Leaf Spring under the Static Load

Condition by using FEA.” International Journal of Mechanical & Industrial Engineering, vol. 1, pp. 1-4

4. Pankaj Saini, Ashish Goel, Dushyant Kumar, (2013), “Design and analysis of composite leaf spring for light

vehicle.” International Journal of Innovative Research in Science, Engineering and Technology, vol. 2, pp. 1-10

5. Mr. Akshay Kumar, Mr. V. J. Shinde, Mr. S. S. Chavan, (2014), “Design, Analysis, Manufacturing and Testing

of Mono Composite Leaf Spring Using UD E-Glass Fiber/Epoxy.”International Journal of Advanced Technology in

Engineering and Science, vol. 2, pp. 112-121

6. M. Sureshkumar, Dr. P. Tamilselyam, G. Tharanitharan, (2015), ),“Experimental Investigation of Hybrid Fiber

Mono Composite Leaf Spring for Automobile Applications.” International Journal of Mechanical Engineering and

Research, vol. 5, pp. 89-93

7. K. Nagendra Babu, P. Sudheer kumar, (2016), “Design and analysis of Jute / E-Glass / Epoxy Composite

Mono-leaf Spring of varying c/s area using Ansys14.5” International Journal of Innovations in Engineering and

Technology, vol. 7 pp. 244-254

8. Achamyeleh, A Kassie, R Reji Kumar and Amrut Rao,(2014), “Design of single composite leaf spring for light

weight vehicle.” International Journal of Mechanical Engineering and Robotic Research, vol. 3, pp. 191-197

9. Ms. Surekha Sangale, Dr. Kishor B. Kale, Dhighe Y. S. (2015), “Design analysis of carbon / Epoxy composite

leaf spring.” International Journal of Research in Advent Technology, vol. 5, pp. 172-178

10. Sushil B.Chopade, Prof.K.M.Narkar, Pratik K Satav, (2013), “Design and analysis of Eglass/Epoxy composite

mono-leaf spring for light vehicle.” International Journal of Innovative Research in Science, vol. 4, pp. 18801-18808

Documents

Design Analysis and Experimental investigation of Composite … · 2017. 7. 12. · 4) Static analysis of standard Steel leaf spring and composite E-glass/Epoxy leaf spring using