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Research Journal of Recent Sciences ______Vol. 1(2), 92-96, Feb. (2012)

International Science Congress Association

Spring made from glass fibre and epoxy to rsteel springs. GRP leaf springs showed a supand fail-safe characteristics 9. M.L. Aggaimprovement in fatigue and fretting fatigueleaf springs used in automotive vehicles. Theof 65Si7 spring steel has been evaluated exp

function of shot peening parameters forautomotive vehicles 10. The main objective ofperform finite element analysis of multi lexperimental results have been taken on aload testing machine, in which leaf spring iaxial load at centre till maximum defexperimental results will be compared withvalidation.

Material and Methods

Material properties and Design parametebelow is showing the different parameters relproperties;

Table-1Material Properties

Parameter ValueMaterial selected- steel 65Si7/S

Youngs Modulus, E 2.1* 10 5

Poissons Ratio 0.266

BHN 400-425Tensile strength Ultimate 1272 MP

Tensile strength Yield 1158 MP

Spring stiffness 221.5 N/

Mass 54.165 k

Normal Static loading 35000 NDensity 0.000007

Behavior Isotropic

Design parameters of the multi leaf spring usare:Total span length (eye to eye): 145Number of full length leaves: 02Length of full length leaves (L-1 and L-2): 14Width of all leaves: 70Thickness of all leaves: 12Number of graduated length leaves: 07

Length of graduated length leaves;(L-3, L-4, L-5, L-6, L-7, L-8 and L-9): 1321140mm, 940mm, 800mm, 640mm, 464mmrespectively.

Multi Leaf Spring Geometery and BoundaThe two dimensional drawing of the multishown in the figure-1 below;

_____________________________________________

place four leaferior endurancerwal describedperformance offatigue strengthrimentally as a

application inthis work is toaf spring. Theull scale staticheld under an

lection. TheseEA results for

s: The table-1ated to material

P9

/mm 2

a

a

m

85 Kg/mm 3

ed in this work

0mm

50 mm eachmm

mm,& 244mm

ry Conditions:leaf spring is

FigurDrawing of Mul

The multi leaf spring is mmaximum deflection i.e. flat preverse direction to attain itelliptical.

The boundary condition is thepressure, velocity, supports, corequired for complete analysisspring is drawn at flat conditionin downward direction to achieAs no load camber is 153,considered for both revolute jThe boundary conditions forshown in the figure-2 below;

Figur

Experimental BounModeling & Finite ElementCAD modeling software is dediof 3D-modeling. The modelstructures also includes manydifficult to make by any of othFinite Element software. CADMulti Leaf Spring structure isV5 R17 software. CATIA i

_______ ISSN 2277-2502 Res. J. Recent Sci.

93

-1i Leaf Spring

delled in position havingsition 11 & will be loaded in

original shape i.e. semi-

ollection of different forces,straints and every condition. As per specifications thetherefore the load is applied

ve initial no load condition.a joint rotation of 27 isints, during static analysis.

he experimental results are

-2

dary ConditionsAnalysis: CAD Modeling:cated for the specialized jobof the multi leaf spring

omplicated parts, which arer CAD modeling as well asmodeling of the complete

performed by using CATIAs having special tools in

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Research Journal of Recent Sciences ____________________________________________________________ ISSN 2277-2502 Vol. 1(2), 92-96, Feb. (2012) Res. J. Recent Sci.

International Science Congress Association 94

generating surface design to construct typical surfaces, whichare later converted into solid models. Solid model of all partsof the structures are then assembled to make a completestructure. The process of assembly is very much analogous togeneral process of fabricating structures while realproduction. The CAD model of multi leaf spring used for FE

Analysis during assembly is shown in figure-3 and figure-4.The assembled CAD model has been prepared from variouspart modeling drawings.

Figure-3Assembly Design in CATIA

Figure-4Assembly Design in CATIA

Finite Element Analysis: A stress-deflection analysis isperformed using finite element analysis (FEA). The completeprocedure of analysis has been done using ANSYS-11. Toconduct finite element analysis, the general process of FEAis divided into three main phases, preprocessor, solution, andpostprocessor.

Preprocessor: The preprocessor is a program that processesthe input data to produce the output that is used as input tothe subsequent phase (solution). Following are the input datathat needs to be given to the preprocessor: i. Type of analysisii. Element type iii. Real constants iv. Material properties v.Geometric model vi. Meshed model vii. Loading andboundary conditions.

Solution: Solution phase is completely automatic. The FEAsoftware generates the element matrices, computes nodalvalues and derivatives, and stores the result data in files.These files are further used by the subsequent phase(postprocessor) to review and analyze the results through thegraphic display and tabular listings.

Postprocessor: The output from the solution phase is in thenumerical form and consists of nodal values of the fieldvariable and its derivatives. For example, in structuralanalysis, the output is nodal displacement and stress in theelements. The postprocessor processes the result data anddisplays them in graphical form to check or analyze theresult. The graphical output gives the detailed informationabout the required result data.

The multi leaf spring with all boundary conditions andmaterial properties is imported in ANSYS-11, showing infigure-5, figure-6, figure-7 and figure-8.

The material used for the leaf spring for analysis is structuralsteel, which has approximately similar isotropic behavior andproperties as compared to SUP9.

Figure-5Multi Leaf Spring Assembly

Figure-6Eye end with pin

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Research Journal of Recent Sciences ____________________________________________________________ ISSN 2277-2502 Vol. 1(2), 92-96, Feb. (2012) Res. J. Recent Sci.

International Science Congress Association 95

Figure-7Meshing of Assembly

Figure-8Boundary Conditions in ANSYS-11

Result and Discussions

As the finite element analysis of multi leaf spring isperformed using ANSYS-11 detailed above, in which allconditions are considered which were also considered forresults taken by experimental testing. The multi leaf springshowing deflections under full & half rated loads are shownin figure-9 and figure-10, as well as in tabular form takenfrom ANSYS-11.

Figure-9Deformation at Full Load

Figure-10Deformation at Half Load

Result Comparison & Discussions:

Table-2Result Comparison at Full Load

Parameters ExperimentResults

FEA Results Variation

NormalStatic Load

35000 N 35000 N Nil

Deflection 158 mm 157 mm 0.632 % Spring Rate 221.5 N/mm 222.92 N/mm 0.641 %BendingStress

101.8Kgf/mm 2

113.25Kgf/mm 2

10.11 %

As shown in the above table-2 deflection and the bendingstress are compared for experimental and FEA results. Theexperimental deflection value is 158 mm and the FEA valueis 157 mm i.e. a negligible difference is detected. On the

other hand the bending stress is increased from 101.8Kgf/mm 2 to 113.25 Kgf/mm 2 i.e. again a negligibledifference is detected.

Table-3Result Comparison at Half Load

Parameters ExperimentalResults

FEAResults

Variation

NormalStatic Load

17500 N 17500 N Nil

Deflection 79 mm 78.5 mm 0.632 %Spring Rate 221.5 N/mm 222.92N/mm 0.641 %BendingStress

48 Kgf/mm 56.62Kgf/mm 2

17.95 %

As shown in the above table-3 the deflection and the bendingstress with half rated load are compared for experimental andFEA results. The experimental deflection value is 79 mm andthe FEA value is 78.5 mm i.e. a negligible difference inExperimental and FEA value. On the other hand the bendingstress is increased from 48 Kgf/mm 2 to 56.62 Kgf/mm 2 i.e.the experimental value is lower than the FEA value but notfar away .

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