project catia - submit

5/24/2018 Project Catia - Submit

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COURSEWORK2

BPILLAR

RE

DESIGN

Submittedby:

GurushishSinghGrover

5331622


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M10MAECOMPUTERAIDEDENGINEERINGBPILLARREDESIGN

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TableofContentsListofFigures.............................................................................................................................2

Listof

Tables

..............................................................................................................................

3

ExecutiveSummary...................................................................................................................4

1. Introduction.......................................................................................................................5

2. ProblemStatement...........................................................................................................6

3. LiteratureReview..............................................................................................................7

3.1.FiniteElementAnalysis(FEA):........................................................................................7

3.2.LoadCaseStudy:.............................................................................................................8

3.3.Meshing..........................................................................................................................9

3.3.1.MeshingSize............................................................................................................9

3.4.EuroNCAP....................................................................................................................10

4.DesignModification.............................................................................................................11

4.1.DesignParameters........................................................................................................11

4.1.1.SecondMomentofArea.......................................................................................11

4.1.2.Material.................................................................................................................12

4.1.3.Weight...................................................................................................................12

4.2.Design...........................................................................................................................12

5.ModelAnalysis.....................................................................................................................13

5.1.Procedure.....................................................................................................................13

5.2.Analysis.........................................................................................................................14

5.3.Discussion.....................................................................................................................14

6.2DCADDrawings.................................................................................................................15

7.ConclusionandRecommendation.......................................................................................19

8.Bibliography.........................................................................................................................20


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ListofFiguresFigure1:BPillarStructure(AltairEngineering).......................................................................5

Figure2:

Initial

Analysis

.............................................................................................................

6

Figure3:LoadCase....................................................................................................................8

Figure4:SideCrashTest.........................................................................................................10

Figure5:HatSection(Anoop,2009).......................................................................................11

Figure6:Reinforcement..........................................................................................................12

Figure7:Assembly...................................................................................................................13

Figure8:VonMisesStressandDisplacementonAssembly...................................................14

Figure9:BPillarDraft.............................................................................................................15

Figure10:ReinforcementDraft...............................................................................................16

Figure11:ExplodedDraft........................................................................................................17

Figure12:AssemblyDraft.......................................................................................................18


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ListofTablesTable1:MaterialRestrictions...................................................................................................6

Table2:MeshResults................................................................................................................9


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ExecutiveSummaryThereportisabouttheprojectforredesignoftheBpillarbyaddingreinforcement.The

reportdealswiththedesignandanalysispartofthepillar.Itdiscussesvarioustoolsusedfor

theanalysislikeVonMisesStresses,displacement,etc.Thereportexplainsthedetailsabout

thecontentsrequiredforproperanalysisofthesystemlikeMeshsize,factorofsafety,etc.

ExamplesofotherprojectssimilartotheBpillararealsodiscussed.Theprocedureofthe

designingandanalysiswithrelevantfiguresareshowninthereport.Theforcesappliedon

theBpillarandtheeffectonitandtheresultsarealsodiscussed.Thedifferentparameters

thataffecttheperformanceandstrengthofthepillararealsocommented.


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1. IntroductionTheBpillaristhestructurelocatedbetweenthefrontandreardoorsofthevehicle.Therole

ofthepillarisnotonlytosupportthestructurebutitplaysvitalroleinsidecrashesandroll

overs,helpinginlessdamagetothepeopleinsideit.StructureofBpillarisshowninfig.1

Intheproject,Bpillarwasprovidedandtheobjectivewastostrengthenthepillarforthe

safetyofthepassengers.Ouraimwastofirstanalysethegivenpillarandnotethestresses

anditsdisplacementactingonitwiththehelpofforcesandafterthatredesignthepillarby

addingreinforcementandthenanalysingitagaintodecreasethestressesandthe

displacements.TheBpillartobedesignedwillhavetosustainsideimpactstaticloadof

140KNinYdirection.

Figure1:BPillarStructure(AltairEngineering)


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2. ProblemStatementThematerialoftheBpillarwasgivenandallthepropertieslikedensity,yieldstrength,

youngsmodulus,etc.forthematerialwasgiven. Theanalysisofthepillarwasperformed

firsttocheckthestressesandtheinitialdisplacementofthepillarataforceof14KN.

Figure2:InitialAnalysisThefigureaboveshowsthedisplacementandtheVonMisesstressontheBpillar.Thispillar

neededtoberedesignedtodecreasethedisplacementandthestresswhosemaximumlimit

weregiven.Thematerialforthereinforcementwasalsogivenwithitspropertieslike

density,yieldstrength,etc.TablebelowshowsthedescriptionoftheBpillarand

reinforcementsmaterialandmechanicalproperties.

Component

Maximu

m

Thickne

ss(mm)

Material

Density

(Kg/m3)

Youngs

Modulus

(GPa)

Yield

Strength

(MPa)

Tensile

Strength

(MPa)

Poisons

ratio

BPillar 1.4 CPSteel800/1000 7850 210 800 10000.3

00

Reinforcement 2.0 HighAlloySteel 7850 210 1500 17000.3

00Table1:MaterialRestrictions

Themaximum

displacement

allowed

was

40

mm

and

maximum

stress

800MPa

for

the

re

designedBPillar.


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3. LiteratureReview3.1.FiniteElementAnalysis(FEA):FiniteElementAnalysisisanumericalprocedureinwhichallthecomplicationsofthe

problemaremaintainedsameandapproximatesolutionsareobtained.Displacementand

stressareconsideredtobeimportantFieldVariablesofsolidmechanicsinFEA.(Gupta,

2003).

Inacontinuum,FieldVariablesareinfinite.Theseinfinitevariablesarereducedtofinite

numberbydividingregionintoelementsandexpressingtheunknownfieldvariablesas

approximatingfunctions.Theseapproximatingfunctionsarecallednodalpointsornodes.

SotheunknownarethefieldvariablesofthenodesinFEA.

Nextstepistoassembleelementpropertiesforeachelement.Forexample,mathematically

wecanfindtherelationshipbetweenstiffnesscharacteristicsofeachindividualelement.

[k]e{}e={F}e

Where,

[k]e=ElementStiffnessMatrix,

{}e=NodalDisplacementVector,and

{F}e=NodalForceVector

Toassemblestructureproperty,elementpropertiesareused.Afterthisstep,theboundary

conditionsaredefined.(Bhavikatti,2005)


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3.2.LoadCaseStudy:TheloadsusedinthisprojectareSideImpactstaticloadswhichissimilartothecrashtest

analysisbysafetyregulations.

Theassemblyisfixedat18pointsi.e.9onupperandlowerendseachtoassumethatitis

attachedtothevehicle.Aloadof140KNisappliedonthetopsurfaceofthepillarasshown

infigurebelow.

Figure3:LoadCase


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3.3.MeshingAsignificantstepoftheFEAmethodismeshgeneration.Meshingistheprocessofdividinga

givenbodyintosmallelements.Meshingcanbecharacterisedon3differenttypes:

1.StructuredMesh

2.UnstructuredMesh

3.HybridMesh

Structuredmeshisidentifiedbyregularconnectivity.Elementshavegeometricalproperties

oforderedgrid.Theseareeasytocomputeandrequirelesstimeandmoreelements

whereasunstructuredcontaintrigulationandquadtees ofpointsets.Hybridmeshis

combinationalofstructuredandunstructuredmeshing.Thereisalsoamanualmeshtypes,

knownasfreeandmappedmesh,wherethetypeofmeshismentionedbeforestartingthe

analysis.(O.C.Zienkiewicz,2005).

3.3.1.MeshingSize

TheanalysisoftheinitialBpillarwascarriedoutwithdifferentmeshsizes,andrespective

displacementsandthestresseswerenoted.Andameshsizewasselectedthatwouldbe

appliedagainontheredesignedBPillar.Thetablebelowshowsallthereadingsbetween

meshsizes215.Thehigherthemeshsize,thelesstimeittakestogetresultsoftheanalysis

buttheaccuracyoftheresultdecreasesandviceversa.Sochosemeshsizeof5becauseits

notfineandnottoolargeandtimeforanalysiswillnottaketoomuchtimeascomparedto

meshsize2andtheaccuracywillbegood,ifcomparedwithhighermeshsize.

Meshsize Displacement(mm) Stress(MPa)

15 47.8 8.47*E03

14 51.1 7.19*E03

12 50.3 8.28*E03

10 47.6 8.32*E03

9 45.8 9.35*E03

8 48.2 9.61*E03

7 50.1 1.11*E04

6 50.4 1.09*E04

5 49.4 1.01*E04

4 50.3 1.12*E04

3 49.6 1.25*E04

2 50.8 1.35*E04Table

2:

Mesh

Results


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3.4.EuroNCAPEuroNCAPistheEuropeannewcarassessmentprogrammewhichorganizescrashtestsand

passesontheresultstotheownerofthevehiclewiththeassessmentofthesafety

performanceofthevehicleforimpactsofthevehicleatrealisticinstanceforces.Thereare

basicallytwoimpactassessmentsthatarecarriedout,1.Frontcrashtestand2.Sidecrash

test.Figureofsidecrashtestisshownbelow.(EuroNCAp)

Figure4:SideCrashTest


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4.DesignModificationAfterapplyingforcesontheinitialBpillaranditsanalysis,itisobservedthatdisplacement

ofthepillarismorethan40mmandthestressdistributionisnotuniform.Insomeareas,

thestressismorethantheyieldstrengthofthepillarmaterial,sofactorofsafetycannotbe

consideredfortheinitialpillar.So,toimprovethis,reinforcementshouldbeaddedtotheB

pillartoreducethedisplacementandtohaveuniformstressdistributionwithmaximum

stressbelow800Mpaonthepillar.

4.1.DesignParameters

4.1.1.SecondMomentofAreaSecondmomentofareaisdefinedasgeometricpropertyofaparticularareathatwillreflect

howpointsonthisareaaredispersedonarandomaxis.Itisalsocalledasmomentofinertia

onaplaneareaandareamomentofinertia.

ThecrosssectionoftheBpillarcanbeconsideredashatsection,astheshapeisalmost

similar.Stressdistributionacrosshatsectioncanbeseeninfigure5.

Figure5:HatSection(Anoop,2009)Thesecondmomentofinertiaforhatsection:

2 2

3

Ifwetrytominimizethedeflectionbyincreasingthethicknessofthesection,theweightwill

increase.So

the

reinforcement

plate

with

hat

section

is

preferable.


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4.1.2.Material

Thestressesaredependentonthepropertiesofthematerial.Thedimensionalstructureof

theBpillarcannotbechanged,soareinforcementofalightermaterialwithhighyield

strengthisrequiredtosupportthepillar.SothematerialforthereinforcementisHighAlloy

Steelthatisnormallyusedfortheseapplications.

4.1.3.Weight

ThemaximumweightallowedforredesigningoftheBPillaris5kgandtheweightofthe

pillarwithoutreinforcementis2.4kg,sothereisalimitationofweightforthe

reinforcement.Therefore,thereinforcementshouldbedesignedatplaceswherethe

stressesaremaximum,sothestressdistributionwillbeuniformandthestructurewontfail.

4.2.DesignThereinforcementisdesignedasarectangularmodelwhichwillbeweldedtotheB pillar.

Thisreinforcementwillhelpinreducingthestressdistributiononthecentralsurfacesofthe

Bpillarwherethestressconcentrationswillbehigh.TherewerenochangesmadetotheB

pillar.Figure6showsthereinforcement.

Figure6:Reinforcement


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5.ModelAnalysis5.1.ProcedureThereinforcementisnowassembledwiththeBpillarandnowitisreadyfortheanalysis.

ThisassemblyisnowtransferredtoGenerativeStructuralAnalysis.Materialsspecifiedinthe

projectdefinitionaredefinedtothebpillarandthereinforcement.Theanalysisforthe

resignedpillarissameastheearlieronei.e.triangularmeshwithparabolicelementis

appliedontheelementsoftheassembly.

Propertiesofthematerialsaredefinedtotheassembly.Thethicknessofthereinforcement

isgivenas2mmthatwasthemaximumlimitallowedfordesigningthereinforcement.Line

contactisusedfortheconnectionsoftheassemblyastherewasnopointcontactbetween

thesurfaces.Seamweldingusedtojointhesurfacesofthepillarandreinforcementby

bindingtechnique.Alltherestraintswerefirstappliedontheassemblyasearlierandthen

theforceswereapplied.Figure7showstheassemblyoftheBpillarandthereinforcement.

Figure7:Assembly


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5.2.AnalysisRedesigningtheBpillarwithreinforcementreducedthedisplacementofthepillarbyagreat

value.Thedisplacementofthepillarreducedfrom50mmtoalmost22mm.Thestresseson

theassembly

have

also

reduced

alot

but

at

the

curves

and

the

end

of

the

bpillar

there

are

stillsomehighstressareas.

Figure8showstheVonMisesStressanddisplacementoftheredesignedBpillar.

Figure8:

Von

Mises

Stress

and

Displacement

on

Assembly

5.3.DiscussionLighterandstrongermateriallikecarbonsteelcanbeusedtoreinforce,sothatwilldecrease

theweightwhileincreasingthestrengthofpillar.Andthereinforcementcanalsobegivento

theedgesofthepillar,sotherewillbenohighstresspointsinthestructure.


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7.ConclusionandRecommendationAlltheanalysishasbeendoneandtheresultswererecorded.Buttheproblemwiththe

stressdistributionstillnotsolvedneartheendsofthepillars.Learntsomenewtechniques

fortheanalysisinCATIA.

Istillrecommendchangingthematerial,whichwillaffecttheanalysisandreducethe

stressesandthedisplacement.Andtherewillbelessornopointsoffailureordistributionof

stresseswillbeeven.


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8.Bibliography

AltairEngineering.(n.d.).Retrieved2009,from

http://altairatc.com/europe/Presentations_2009/Session_15/VOLKSWAGEN_

091104_VWAG_EHTC2009.pdf

Anoop,C.(2009).FundamentalsandPreliminarysizingofsectionsandjoints.Delhi.

Bhavikatti,S.S.(2005).FiniteElementAnalysis.NewAgeInternational.

EuroNCAp.(n.d.).Retrievedfromhttp://www.euroncap.com/about.aspx

Gupta,K.(2003).FiniteElementMultidisciplinaryAnalysis.AIAA.

O.C.Zienkiewicz,R.T.(2005).TheFiniteElementmethod:ItsBasisand

Fundamentals.ElsevierButterworthHeinemann.

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