International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p ISSN: 2395 0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page174
HubHub:isthecomponentwhichconnectswheelandtheknuckle togetherandhelpstorotatethewheel.
Asteeringknuckleneedstobedesignedinasuchawaythat itiscapabletowithstandtheforcesandmomentsactingon it due to bumps ,braking ,acceleration and steering of vehicle.Toobtainthepossiblybestridingcharacteristicsofa vehicle and to achieve it, unsprung mass of the vehicle should to be reduced. So, our goal is to design a wheel assemblywhichhaslowestpossibleweight.Duringmaterial selection the main aim is having high strength and less weightascomparedtoothercommerciallyavailableknuckle materials. In this paper we propose Aluminum 7075 T6 compared to Aluminum 6061 T6, Mild steel A36 and StainlessSteelAISI304. Al 7075 T6
1.INTRODUCTION
BrakeDisc: Brakediscisthecomponentofbrakingsystemthathelpsto decelerate the vehicle. It is connected to the wheel hub which results in stopping the vehicle when brakes are CaliperCaliperapplied.:is the component mounted on the knuckle and having brake pads in it generate friction on disc which resultsinstoppingofvehicle.
BearingBearing:isthecomponentinwheelassemblywhichispress fitted in knuckle and helps the hub to move freely while minimizingthefriction.
DESIGN AND ANALYSIS OF FRONT WHEEL ASSEMBLY OF A FORMULA STUDENT CAR Dr. Mohammad Athar Hayat1 , Surendra Dahake2 , Tushar Ghatole3 , Saikiran Mupanna4 , Shubham Pawade5 , Shashwat Kadam6
Thewheelassemblyconsistsoffollowingcomponents: KnuckleKnuckle: is one of the important component of wheel assemblythatholdssuspensionsystemandsteeringsystem components together It has mounting for wishbones, tie rods,bearingand brakecaliperoverit.
LockNut,LockingPlateandCirclips: The lock nut, locking plate and circlips are components whichensuresthesafetyindynamicconditions.
Key Words: FSAE, Wheel Assembly, Knuckle, wishbones, Hub,Brakedisc,Calipers,Solidworks,Ansys.
Abstract - Formula Society of Automotive Engineers (FSAE) is an organization which conduct the Formula Student competitions around the world where student from various engineering colleges participates with their self designed vehicle. FSAE provides the platform for engineering students to apply their engineering knowledge to build a real world Formula Student Car. The purpose for this project is to design wheel assembly for a formula student car while identifying & optimizing the critical component as Knuckle. The purpose of wheel assembly is to provide the physical mountings for the various components in vehicle including Wishbones, Steering Tie rod, Wheels, Brake Calipers etc. The wheel consists of Knuckle, Hub, Brake Disc, Bearing and Locking Components. The goals for designing the wheel assembly is to minimize the weight of wheel assembly as much as possible also to be cost effective while satisfying its purpose. The design of wheel assembly components is done using Solidworks software and structural analysis is done using Ansys software. The material study is done in brief to select the best possible material with better strength to weight ratio.
1Assistant Professor, Dept. of Mechanical Engineering, St. Vincent Pallotti college of Engineering and Technology Nagpur, Maharashtra, India 2,3,4,5,6 U.G. Student, Dept. of Mechanical Engineering, St. Vincent Pallotti College of Engineering and Technology Nagpur ***
1.1 Material Selection
The composition of Aluminum 7075 T6 is 5.6 6.1%Zinc, 2.1 2.5%Magnesium, 1.2 1.6%Copper, and some other materials which are very less in composition like Silicon, Iron, Manganese, Titanium, Chromium etc. The specific strength of Al 7075 is very high. Al 7075 offers a better strength for the steering knuckle component. As in table givenbelowwecanseethatyieldandtensilestrengthsare higher than compared to other materials. It is one of the aluminumalloyswithhigheststrength.
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Poisson’sRatio 0.33
Considerspeedduringturning=40Km/hr Weightdistribution40:60 W=260Kg,W1 =52Kg, h=228.59mm t=1150mm
Young’sModulus(GPa) 71.7 Density (g/cc) 2.81 ShearModulus(GPa) 26.9
Young’sModulus(GPa) 200 Density (g/cc) 7.8 ShearModulus(GPa) 79.3
Asdesignandoptimizationofknuckleisdirectlyrelatedto theweightfactor,ifwereduceweighttheefficiencyofcar automatically get better. So, our main focus is toward the optimization of knuckle so, for optimization we need differentdynamicforcesforanalysis.
Poisson’sRatio 0.33 UltimateTensileStrength 572 YieldTensileStrength 503 Al 6061 T6 ThecompositionofAluminum6061T6isMagnesium0.80 1.20%,Silicon0.40 0.80%, Iron0.0 0.70%,Copper0.15 0.40%Chromium0.04 0.35%,Zinc0.0 0.25%,Titanium 0.0 0.15%, Manganese 0.0 0.15 %, etc. It offers better weldability but for knuckle we need material with good machinability. It is not as strong as Al 7075. It has no problemofcorrosionashavinglessamountofcopper.
Young’sModulus(GPa) 68.9 Density (g/cc) 2.7 ShearModulus(GPa) 26
UltimateTensileStrength 310 YieldTensileStrength 276 Mild steel A36 The composition of Mild Steel A36 is Carbon 0.25 0.29%, Copper0.20%,Iron97%,Manganese1.03%,Phosphorous 0.04%,Silicon0.2%,Sulfur0.05%.Itisoneofthecheapest materials in the list. The material is easily available in market.Itisveryheavy.Thestrengthtoweightratioisvery badascomparedtoAl6061T6andAl7075T6.
1.2 Vehicle Specifications
TheFormulaStudentvehicleisdesignedasperthestandard Rulebook of Formula society of automotive Engineers. Thewheel assemblyistobe designedforthevehiclewith followingspecifications. Dimensions Front Rear Trackwidth(t) 1150mm 1100mm Wheelbase(L) 1550mm Totalweight(w) 104kg 156kg CGheight(h) 229.59mm Turningradius 2.4m Staticweightdistributionisassumedtobe40:60::Front: Rear 1.3 Dynamic Force Calculations
Poisson’sRatio 0.26 UltimateTensileStrength 500 YieldTensileStrength 250 Stainless Steel AISI 304 The composition of Stainless Steel AISI 304 is Iron 66.74 71.24%,Chromium17.5 19.5%,Nickel8 10.5%Manganese 2%,Silicon1%,Nitrogen0.11%,Carbon0.07%,Phosphorus 0.05%,Sulphur0.05%.TheformabilityofAISI304isvery good. Young’sModulus(GPa) 195 Density (g/cc) 8 ShearModulus(GPa) 86 Poisson’sRatio 0.29 UltimateTensileStrength 505 YieldTensileStrength 215 Allmaterialsaremostlyusedwherehightensilestrengthand toughnessisrequired.So,Aluminumalloysaresuitedforthe wheel assembly components. Due to this low weight of materials,itcandecreasethefuelconsumptionandithave lowdensityandsufficientyieldstrength.Al7075T6 being lighterandstrongerthanAl6065T6makesitsuitabletouse forthemanufacturingofKnuckle,HubandBrakeDisk.
Verticalforceduetocentrifugalcouple[5] = {(Total mass with driver) * (velocity) 2 * (Height of COG(H)}/{2*Corneringradius*Trackwidth} =1754.26N Verticalforceduetogyroscopiceffect[5] =Iωωp = 4 * {Mass of each wheel * (Radius of tire(R)) 2/2}* {(Velocity of vehicle)2/ ( Radius of tire *Cornering =radius)}1479.64N Netverticalloadactingonwheel =510.12N+1754.26N+1479.64N =3444.02 CentrifugalNforce(Lateralforce) =mv2/R =3385.41N
actingaboutsteeringaxis =frictionalforce*scrubradius =306.07*28.90 =8845.42N mm Forceactingontierod =TorqueaboutSteeringaxis/lengthofSteeringarm =8845.42/56.60N = Force156.27Nonbrake
Lateralacceleration[6]: (Ay)=(tW 2tW1)/ 2Wh =1.509m/s2/9.81 = Lateral0.15gloadtransfer[6]: (LLT)front = W× lateral acceleration × CG height/ front trackwidth=260×0.15g×228.599/1150=7.752kg (LLT)rear =W×lateralacceleration×CGheight/reartrack width[6]=260×0.15g×228.599/1100 =8.103kg Longitudinalloadtransfer[6]: LLT=W×longitudinalacceleration×CGheight Wheelbase =260×0.5g×228.599/1550 =19.169kg Verticalloadactingoneachwheel=52*9.81=510.12N
Bumpforce =Wheelrate×travelduetobump =1277.79N Forcesonsteeringarm Staticloadononewheel =52*9.81N =510.12N Frictionforce =0.6*510.12N =306.07N As Friction force rotates wheel assembly about steering Torqueaxis.[5]
International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p ISSN: 2395 0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page176
caliper: Frictional force = Coefficient of friction * Total vertical loadononewheel[5] =0.6*1974N=1184.58N Brakingtorqueonthewheelistheeffectoffrictionalforce actinginthecontactpatchoftire. Brakingtorque(Tb)=Frictionalforce*Radiusoftire(R) =1184.58*0.228=270.08N m Forceexertedoncalipermounting(Fc) =Brakingtorque/Distancefromcenterofspindle = 270.08/55 =4910 N
1.4 Bearing Selection
2.1 Knuckle
Thefollowingfiguredescribestheterminologiesinvolvedin upperandlowerballjoint
BallBearing: It can sustain the radial Loads and there is point contact betweenballsandraces. TaperedRollerBearing: In tapered roller bearing there is a line contact and it is capable to withstand radial as well as axial forces. So, taperedrollerbearingperformgoodundershockandimpact loading,weareusingtaperedrollerbearing.[1]
International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p ISSN: 2395 0072
CastorAngle: Insideview,Castorangleistheangleofthelinejoiningthe upperandlowerballjoint.Thevalueofcastorangleaffects theself aligning torqueof wheels. Therefore,5 degrees of castorisusedsoastogetsufficientself aligningtorque.
Inordertostarttheknuckledesign,thetireandwheelsize mustbesettled.Asmentionedbefore,thecarisaimedtobe runningon10"wheelswith8"widthandBKTGOLFCART TIRES205/50 10tireswhichare18"indiameter. The designing of knuckle starts from determining the position of upper and lower ball joint which can be determined by suspension hard points selection and the requiredparameterssoastoimprovethevehicledynamics ofthe Followingvehicle.factorsareusedforknuckledesign bystudying thedynamicbehaviorofthevehicle.
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KingpinInclination(KPI):
DataforBearingSelection: RadialLoad=Fr=1974.3N AxialLoad=Fa=3461.45N EquivalentLoad=Fe=(XFr+YFa)*Ks*Ko*Kp*Kr[2] ForTaperedrollerbearing,C=0.35 Fa/Fr=3461.45/1974.3=1.75 AsFa/Fr>c X=0.40,Y=2 Ks=Servicefactor Ks=1.3formoderateshock Ko=Kp=Kr=1 Fe=(0.40*1974.3+2*3461.45)*1.3*1*1*1 Fe= L=(C/Fe)L=360L=5000*60*1200BearingSpeedAssuming,10026.4N=1200rpmlife=L=5,000hrmillionRevolutions n *Kret Where c=Dynamicloadcapacity n=10/3fortaperedrollerbearing Kret=reliabilityfactor WearetakingKret=1for90%reliability 360=(C/10026.4)10/3*1 AsC=58.6kNpertheabovedatawehavetoselectthebearingwhich cansustaintheaboveloads. So,FromSKFbearingcataloguewehaveselected32305 2FDbearingwhichishaving Internaldiameter=25mm Outerdiameter=62mm Width=25.25mm[3] 2. DESIGN METHODOLOGY OF COMPONENTS
In front view, the king pin inclination is the angle of line joining the upper and lower ball joint. The king pin angle reducesthescrubradiusofthetiresandmorevalueofking pininclinationleadstocambergain.Therefore6degreesof KPIisusedaspersuspensionsimulationsandpreviousyear data so as to get the required scrub radius and minimum cambergain.
Atthefrontwheelsthetypeofforceswhichactsareradialas wellasaxialforces.Thisisduetothereasonthevehicleload actsonthewheelaswellasaxialthrustactswhilecornering. Thus, it becomes important to use a bearing which can sustainradialaswellasaxialforces. There are majorly two bearing which are usually used in frontwheelassembly.
Fig 3: Ackermangeometry,withsteeringrackbehindthe axleline BearingandCaliperMounting: TheBearingmountingisdesignedasperthedimensionsof Bearingtobeused. TheCalipermountingisdesignedasperthestandardKBX OEMCaliperandconsideringtheBrakeDiscDiameter.
Arm:Theangleandlengthofsteering armdefinesthevalueoftypeofgeometryofthesteeringand thewheelangleperunittravelofsteeringtierod. The inputs from Ackerman steering geometry is taken considering the speed characteristics of formula student vehicle, low speed geometry i.e., Ackerman steering geometryisusedfordesigningthesteeringarm Fig.2 Ackerman,ParallelAckerman,ReverseAckerman Geometries
2.2 Analysis of Knuckle
Fig 1:TerminologiesinUBJandLBJ Ackerman Inclinationsteering:ofSteering
TheKnuckleisdesignedbytheiterativeanalysismethodand weight is reduced from the areas where the stress concentrationislessandaccordinglythedesignisoptimized andfinalized Fig-4 AnalysisofBasicKnuckle
International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p ISSN: 2395 0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page178
International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p ISSN: 2395 0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page179 Fig 5:AnalysisofFirstIteration Fig -6:Analysisofseconditeration Fig 7:Analysisoffinaliteration 2.2 Hub
Fig 8:
TheHubisdesignedbytakingtheconstraintsfromwheel rim and brake disc and bearing and structural analysis is donetochecktheloadbearingcapacityofthehub. Analysisof Brake disc
TheBrakeDiscistheimportantcomponentsoastostopthe vehicle.Thephysicaldimensionsofthediscisdecidedasper the theoretical calculations and analysis is done so as to checktheloadbearingcapacityoftheknuckle.
WheelHub 2.3
4. ACKNOWLEDGEMENT
REFERENCES
Fig-10:FinalWheelAssembly
3. CONCLUSION
International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p ISSN: 2395 0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page180 Fig-9:AnalysisofBrakeDisc After designing and analyzing all the components the componentsareassembledtogethertogetausefulproduct with rule compliance as per the FSAE community i.e., the knuckleisincorporatedwithpositivelockingmechanismby usinglockingplateandlocknut.
[1] Joijode Vrushabh Umesh, Yadav Abhishek, “Designing and Optimization of Wheel Assembly of a Formula Student Car,” Mechanical Engineering Department, Vishwakarma Institute of Technology, Pune 37, India, March2016 [2] V.BBhandari,“EngineeringDesignDataBook” [3] SKF,“BearingCatalog” [4] McGraw Hill,JosephE.Shigley,“STANDARDHANDBOOK OFMACHINEDESIGN”
Wewouldsincerelyliketothankourguide,Prof.M.AHayat for his helpful guidance and assistance throughout the durationofthisproject.ManythanksalsogototheHeadof Department, Prof. Pramod Lanjewar for his continuous effortsfortheFormulaSAEteamandhissupervisionover the event. Lastly, we would also like to thank our project reviewcommitteemembersProf.M.SKhanandProf.H.N Nagpure
Thegoalforthisprojectistodesignandanalyzethe formula student wheel assembly while the major focus was to optimizetheknuckle.Othercomponentsaredesignedsoas to sustain the dynamic and static forces acting on it. The designofknuckleisdonewhilekeepinginmindtheprevious yearsdesignandproblemsfacedinit.Weimplementedthe shapeoptimizationtechniquetooptimizethedesignofthe knucklewhichistobeusedinthefrontwheelassemblyof thecar.Themainobjectiveoftheshapeoptimizationisto reducetheweightoftheknuckle.Asreductioninweightof theknucklewilltendreducetheweightoftheoverallwheel assembly.Theresultshaveshownthatfortheknucklewe havereducedalmost40percentofweight
[5] KritikaSingh,KanishkaGabel,“CalculationofDynamic ForcesandAnalysisofFrontUprightforATV”,Student Department of Mechanical Engineering, National InstituteofTechnology,Raipur,Chhattisgarh,India
[6] Milliken & Milliken, “Race Car vehicle dynamics”, SAE International,1995,ISBNI56091 526 9
[7] FormulaBharat,“FormulaRulesBook2022”
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[8] ThomasGillespie,“Fundamentalsofvehicledynamics”, SAEpublications,1992,ISBN978 81 89401,pp5 6
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