FABRICATION AND ANALYSIS OF AUTOMOTIVE SANDWICH FRP REAR SPOILER

INTERNATIONAL JOURNAL OF COMPUTER APPLICATIONS INENGINEERING, TECHNOLOGY AND SCIENCES (IJ-CA-ETS)

FABRICATION AND ANALYSIS OF AUTOMOTIVE SANDWICHFRP REAR SPOILER

1SYED MUDASSIR, 2DR. MANZOOR HUSAIN, 3DR. D. V. RAVI SHANKAR,4DR. RAM REDDY

1Asst. Prof. Dept of Mechanical Engg, Nizam Institute ofEngineering and Technology, Deshmukhi, Nalgonda .

2Professor, Mechanical Engineering Department, JNTU Hyderabad.3Principal, Nizam Institute of Engineering and Technology,

Deshmukhi, Nalgonda (Dt.,).4 Prof., Mechanical Engg, Principal Malla Reddy Engg College

for Women, Hyd. & Former -registrar JNTU Hyderabad.

[email protected] , [email protected] ,[email protected]

ABSTRACT :The NACA 4digit series aerofoil shapes are universally accepted standard designs generally used forwind turbine blades, helicopter rotor blades and car spoilers. The manufacturing of these complexshapes is a challenging task for the manufacturing engineers. These components need to be made ofmaterials having high specific strength and fatigue properties. The composites with sandwichconstruction fulfill the above requirements. The main aim of the present Investigation is to select thebest fiber orientation for the fabrication of automotive rear spoiler. The Design FOIL softwareprovides different shapes of aerofoil from which NACA 2412 has been selected. The spoiler is modeledusing CATIA software and is analyzed for the static deflection using ANSYS for various orientations ofthe fiber. The spoiler is then fabricated using woven E-glass fiber (with the best orientation) and epoxyresin. Static test is performed on the fabricated model to validate the results obtained from thesoftware. This confirms the design feasibility and software adoptability for the design of sandwichaerofoil shape.

1. INTRODUCTION A car spoiler is a wing likeaccessory that is usually attachedto the rear end of the cars, ornormally mounted on top of a car'strunk or positioned under the frontbumper. While the rear spoiler issometimes called 'wing', the frontalcar spoilers are also called 'airdam'. Car spoiler dynamicallyimproves the external beauty of thecar making the car stand out in acrowd, making it more trendy andsporty. In automobile parlance, aspoiler is an aerodynamic device

that is attached to an automobile.The intended function of this deviceis to 'spoil' unfavorable airmovement across a body of vehicle ofsome kind in motion. It is customary for racing and otherhigh performance sports cars to befitted with spoilers. Nowadays-evenpassenger vehicles use spoiler verycommonly. To put it more succinctly,a car spoiler improves theperformance of the car and evensometimes stimulates its resalevalue of the car.

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The next area for development was tomanage the airflow underneath thecar; firstly this was done by usingsuction fans in the 1970’s, onceagain by Chevrolet-Chaparral.However this car was banned as thecornering speeds reached, up to1.7g, were thought too dangerous.This was taken on by Lotus when in1978 the Lotus 79 had a fully shapedunderbody to channel the airflow,

this car was also banned. Modern dayFormula One cars can now reachcornering speeds of up to 5g, eventhough there are very strictrestrictions in the guidelines. Thisshows how far automotiveaerodynamics have been improved.The introduction of the car spoilerbegins in the 1960s, when NASCARautomobiles still looked like whatyou drove on the street. In 1966,the Dodge Charger had a flatter noseand a long, sloping roofline thatseemed to make the car unstable andlift at higher speeds. NASCAR waspetitioned and they allowed theDodge teams to a piece of metalabout one-half to two inches high tothe rear deckled. This trapped airon the decklid and created downforce to stabilize the car. It didnot make the Dodge a standout car,but other manufacturers did see theaerodynamic perk of adding somethingto the back of the car to increasedown force.2. EXPERIMENTATION In the present work the fabricationof the spoiler can be divided asfollows.

o Template preparation.o Skeleton preparation.

o Molding of foam in to arequired shape.

o Stacking of fibers ontothe polyurethaneaerofoil shape.

o Experimental setup

3.TEMPLATE PREPARATIONThe main aim of the template is toachieve the aerofoil shape for thepolyurethane foam. A wooden block of

considerable length is taken on towhich an aerofoil outline is pasteand cut according to the requiredshape. In the similar manner theemore templates are prepared and twoholes are drilled with considerabledistance on length.

Fig 1: Preparation of aerofoiltemplates

Fig 2: skeleton of aerofoil

Fig 3: placing of foam in to askeleton.

3. Skeleton preparation

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The templates prepared are placedequidistant and aluminum rods arepassed through the holes and bondedwith an adhesive.4. Molding of foam in to a requiredshapeAfter the skeleton is prepared thefoam is placed on both of theskeleton and fixed together with anadhesive, and then it is allowed todry. The dry part is ground using asand paper to the required shape.5. Stacking of fibers onto thepolyurethane aerofoil shape:After the polyurethane foam isgrounded, into the aerofoil, shapestacking of the fibers is done.Before stacking fibers the wovenfiber has to be placed in a propersequence with proper orientation.For this a Sharpe knife is used incutting fibers in requiredorientation sequence. The angle ofply is maintained to 45-degrees andto measure the angle a bevelprotractor is used. The wrapping offibers onto the polyurethaneaerofoil shape is done using thehand layup method. In this method amiler film is placed onto which thefibers oriented in a particularangle ply i.e., [±45] are placed.The epoxy resin and the catalyst aremixed proportionately in a bucketand apply on to stacked fibers. Aroller is used to impregnate resinthroughout the fabric. Then thepolyurethane aerofoil shape isplaced at the center of the lay-upand then the miler film along withthe stacked fibers is bent onto theaerofoil shape and then it isallowed for curing.

Fig 4: Applying a resin in tostacked fibers.

Fig5: removal of spoiler aftercuring.

6. Experimental setupA simple static deflection test rigsetup is made fort the deflectiontest. The U channels are weldedtogether as shown in fig .the spanbetween the two supports ismaintained approximately 1 meter. Togive the fixed end conditions at theend recessions are made which fixedexactly onto the test rig. Thespoiler is fixed into a spaceprovided and applies the uniformlydistributed load. To make a staticresults for the different loadingconditions. A dial indicator hasbeen used to measure the deflectionsof a various loading conditions.7. Experimental ResultsThe load is applied step by step andthe deflection at each load is notedand are tabulated in table 1.8. STEPS IN ANALYSISProcessor:Input to the problem depends uponthe number of materials in the modeland as in the present work twomaterials Foam and composite Skinare used. Foam is an isotropicmaterial so it requires at least twoproperties to be defined. density,youngs modulus and poisons ratio isgiven as input for Foam. Ascomposite skin is made up ofanisotropic material it requires isat least four properties to be



defined. Density, Youngs modulus inx-direction, Youngs modulus in y-direction, major poissons ratio andminor poisons ratio and shearmodulus are input to the skin.Creation of the Finite Element Modelis carried out in the solution.

Fig 6: Fixing of spoiler in theexperimental setup.

Table 1: Experimental deflectionvalues.

Solution:A uniformly distributed Load isapplied along the length of thespoiler all degrees of freedom isconstrained at both ends of spoilerthat of in fixed beam.Postprocessor:In post processor the requiredresults are obtained Resultant deformations3 Stress distribution, von-misses

stresses Deformation in static and dynamic

load directionAnsys results

Fig 7: meshed model

The assembled model then is importedinto ANSYS workbench 11. Meshing hasbeen done using mesh option as shownin figure The finite element modeling andanalysis is used to study thedeflections and stress variation atdifferent locations of the spoilerand also the deflection at variousends. The figure shows all thedeflection stresses and harmonicAnalysis of different orientations.RESULTS FOR 00 ORIENTATION

Fig 8: Deflection at 00 orientation

Fig 9: Equivalent stress 00

orientation


Load applied kg

Deflection measuredmm

50 3.12

100 4.23

150 5.7

200 7.7

250 9.9

300 11.05


Fig 10: Frequency Vs Amplitude (00).Table 2: Results for Harmonic

analysisRESULTS FOR 450 ORIENTATION

RESULTS FOR 450 ORIENTATION

Fig 11: Deflection at 45o

orientation.

Fig 12: Equivalent stress 45o

orientation

Fig 13: Frequency Vs Amplitude (450)

Results For 600 Orientation


orientation.


orientation


Minimum

Frequency0. Hz

MaximumFrequency 2000. Hz

Display BodeResults

MaximumAmplitude 2.3267e-007 m

Frequency 800. HzReal -2.3267e-007 m

Imaginary 0. m


Fig 16: Frequency Vs Amplitude (600)

Table 4: Results for Harmonicanalysis.

RESULTS FOR 900 ORIENTATION:


orientation.


orientation.

Fig 19: Frequency Vs Amplitude(900).

Table 5: Results for Harmonicanalysis.


Minimum Frequency 0. HzMaximum Frequency 2000. Hz

Display BodeResults

Maximum Amplitude 1.632e-006mFrequency 800. Hz

Real -1.632e-006mImaginary 0. m


Display BodeResults




Display BodeResults




Orientation ofglassfiber

Deflection(mm)

Von-missesStressN/mm2

Peakfrequen

cy

[0]3 11.595 186.98 800[±45] 3 9.057 141.49 1400[±60] 3 15.183 741.03 800[90] 3 18.696 735.65 1000

Table 6:Results comparison.

9. Theoretical Calculations:A spoiler can be assumed to be fixedsupport beam with uniform loadingthen the deflection is given by

δ=1/384*Wl4/EI.EI is called as flexural rigidityand it depends upon the materialproperty and area moment ofinertia.

Table 7: For 0-degreeorientation

Property

Sandwichconstruction(E-glasspolyesterskin)

P-U FoamProperties

Young’s

Modulus (E)

Exx =55.05Gpa

Eyy =10.69Gpa

39.9x10-3 GPa

Density (ρ) 2205.2 kg/m3 40 kg/m3

Momentof

Inertia (I)

161336.86829mm4

141864.96951mm4

Flexural

rigidity

EIxx foam + EIxx skin =7816.104N-m2

δ=1/384*2679.55* (1)4/7816.104. δ= 0.000893 meters.

Table 8: For 45-degreeorientation.

Property

Sandwichconstruction(E-glasspolyesterskin)

P-U FoamProperties

Young’s

Modulus (E)

Exx =53.662 Gpa

Eyy =9.9917 Gpa

39.9x10-3 GPa

Density (ρ) 2205.2 kg/m3 40 kg/m3

Momentof

Inertia (I)

161336.86829mm4

141864.96951mm4

Flexural

rigidity

EIxx foam + EIxx skin7619.195N-m2

δ=1/384*2679.55* (1)4/7619.195.δ=0.000916 meters.


Property

Sandwichconstruction(E-glass

polyester skin)

P-U Foam Properties

Young’s

Modulus(E)

Exx =10.5462G

pa

Eyy =27.7734Gpa

39.9x10-3

GPa

Density(ρ)

2205.2 kg/m340 kg/m3

Moment ofInertia(I)

161336.86829mm4141864.969

51mm4

Flexu EIxx foam + EIxx skin =



ral rigidity

1502.574N-m2

δ=1/384*2679.55* (1)4/1502.574. δ= 0.004644 meters


Property

Sandwichconstruction

(E-glasspolyesterskin)

P-U FoamProperties

Young’s

Modulus(E)

Exx =10.6732G

pa

Eyy

=55.05Gpa

39.9x10-3 GPa

Density(ρ)

2205.2 kg/m340 kg/m3

Moment ofInertia(I)

161336.86829mm4

141864.96951mm4

Flexuralrigidity

EIxx foam + EIxx skin=1520.591N-m2

δ=1/384*2679.55* (1)4/1520.591 δ=0.004589 meters.

(±450)RESULTS FOR WITHOUT FOAM.

Fig 20: Deflection.

Fig 21: Equivalent stress.

Fig 22: Frequency Vs Amplitude.

Table 11: Results for Harmonicanalysis

Table 12: Foam and without foamResults comparison (±450)

Material

Deflection(mm)

Von-misses

Stress

N/mm2

Peakfrequency (Hz)


Minimum

Frequency0. Hz

Maximum

Frequency2000. Hz

ResultsMaximum

Amplitude7.7927e-007 m

Frequency 400. HzReal -7.7927e-007 m


WithFoam

9.057 141.49

1400

WithoutFoam

15.946 186.98

400

10. CONCLUSIONS The simulation results is that

[±45o] orientation of thefiber is the best orientationfor the fabrication of thespoiler.

The fabrication of the spoilerhas been done with sandwichconstruction.

The static deflection test wasconducted on the model anddeflection is found to be9.15mm.

The theoretical calculationand the simulation resultsdiffer i.e., due to localizedbuckling effect in thesandwich construction.

11. REFERENCES[1] A.B. Lovins et al. Hyper cars:

the coming light vehiclerevolution. Proc. ISATA Conf.,Aachen, Germany, Sept. 1993.

[2] B. O’Rourke. The contributionof composite materials to aworld champion Formula 1 racingcar design. Proc. 14th Int. SAMPEEuropean Chapter Conf., Birmingham,UK, Oct. 1993.

[3] H. Allen. Sandwich constructiontoday and tomorrow. Proc. 1st Int.Conf. on Sandwich Constructions, RoyalInst. of Technology, Stockholm,Sweden, June 1989.

[4] W.J. Wingenbach. Limitation ofintrusion during side impact.Proc. 2nd Int. Tech. Conf.on ExperimentalSafety Vehicles, Sindelfingen,Germany, 1971 (quoted in HexcelComposites Information SheetATC 183a).

[5] W.J. Cantwell et al. Acomparative study of the

mechanical properties ofsandwich materials for nauticalconstruction. SAMPE Jnl., 30 (4),45-51 (1994).

[6] R. Seiss. Presentation to NRCIrvine Hearing on behalf of DowChemical Co., 8 July 1991.Source: Rocky MountainInstitute(http://www.rmi.org/).

[7] K. Lowe. Automotive steels.Engineering, Feb. 1995, 20-21.


FABRICATION AND ANALYSIS OF AUTOMOTIVE SANDWICH FRP REAR SPOILER

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