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CAD Final Report Submission C
- 1. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 1 of 9 CAD Report for Module 104AAE The group that thisreportconcernswas: AdamRush,StevenKendell,AbhishekDabas.(There were twoothermemberswhodropped out of the group duringthe course theywere TanuChaturbedi andKarolinaKuk.) Introduction Honeycomb structures are commonly found in aerospaceapplicationsand haveexceptional strength to weightratiowhichisnecessaryformanystructural componentsespeciallyinaircrafts.High strengthmaterial suchas steel andtitaniumhave significantly largerweightthanweakermaterials (copper).Thisresultsinacompromise tobe made;where amaterial hassufficientstrengthandis relativelylightsuchasaluminium.Thismakesaluminiumaperfectmaterial tocreate a honeycomb structure from.Whendesigningsuchstructuresitisadvantageoustopredictthe capabilitiesof the designedstructure before itismanufactured.“Finite elementanalysis(FEA) isacomputerized methodforpredictinghowaproduct reactsto real-worldforces,vibration,heat,fluidflow,and otherphysical effects.”(http://www.autodesk.com 10/12/15) FEA can alsogive visualisationsof deformation,displacementandthe Stressdistributionswithinthe structure. The objectiveof this workis to create a honeycombstructure fromAluminium3003 and use FEA to testitsphysical propertiesinthe Wand L direction. Honeycomb Core Structure. The Beginning: Once the group had beenestablished,we all decidedto tackle the honeycombcore asour CAD project.Thiswe all feltwasthe one bestsuitedtoour skillsandconfidence inourCAD capabilities. From there we all startedgoingthroughthe tutorialsorplayingaroundwithcreatinga (honeycomb) cellinCatia.Afterawhile membersof the grouphadmade differentlevelsof progress. StevenandDean(Abhishek) hadgone throughthe tutorialswhereasAdamhadworkedtowards creatinga honeycombcell.Butthere wasa problemwithone of ourfoundinggroupmembers, Tanu had decidedtogopart time inher learningandtherefore droppedthe CADmodule.Howeveranew memberwasfoundinKarolina.Fromhere all membersof the groupworkedoncreatingthe full honeycombstructure asdefinedinthe courseworkhandout. The Middle: All membersmade significantprogresswithcreatingthe fullstructure,we all learnedvarious methodsof creatinga cell andthenwe learnedvariouswaysof multiplyingthatcell togive usa full 20 by 22 structure of cells. One of the more challengingpartsof the modellingwascreatingthe thicknessof the cell walls,one methodusedwastocreate a polygonaroundthe initial polygonand setthe distance betweenthe innerandouterpolygonstothe requiredamount. The End: By the time the secondsubmissionwasapproachingwe nearlyhadafull working honeycombcreatedbySteven,thisishow he didit.Itwas created,firstbyproducinga hexagonal shape ina plane,producingaconstraintwhere the sidesare of length4.1mm.Fourmore were then createdparallel toeachotherto create 5 columns,eachhexagonisseparatedby0.1mm.Using the axistool I placeda vertical line thatwasparallel tothe vertical cell wallsof the hexagon,separated
- 2. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 2 of 9 by 0.5mm fromthe hexagoninthe lastcolumn.Iusedthe mirror tool,whichallowedforme to selectthe 5 hexagonsandmirrorthemalongthe axis,I repeatedthisselectingthe 10hexagonsand mirroringthemina newaxis,resultingin20 columns.We thenexitedthe planeandusedthe pad tool,tickingthe box labelled‘thick’,thensetthickness1& 2 to 0.5mm. I thencreatedanotherimage inthe same plane beneaththe firstrow,creating20 columnsof hexagonsonce again.A constraint betweenthe firstrowsinnercell wallandthe secondrowscell wall of 0.5mmwas created.This ensuredthatwhenthe padtool was usedon the secondpart,and the correct thicknesseswasset, that the vertical wallswouldbe 0.2mmthick,comparedtothe otherswallsthicknessof 0.1mm. I mirroredeachpart separately,mirroringthe firstrow 11 times,thenrepeatingforthe secondrow, thuscreatinga total of 22 rows.By creatinga distance of 2.021mm betweenthe axisline andthe bottomof the rowof hexagonsIwasable to mirror the row of hexagonssothat theyconnected with the correct measurementstothe rowsof hexagonsadjacent.A picture of the CATIA model isshown inFigure 1. The group was organisedandkeptontrack by the use of the WhatsAppappand outlook e-mail’snew groupsetting,sothatfilescouldbe shared. FEA Testing and analysis. Adam Rush’s Tests: “For the testingandanalysisIdecidedtobase my investigationsonthe VonMisesstress levelsthatare showninthe CatiaFEA component.Havingneverheardof VonMisesstressIdecided to lookitup on the internet.Ifoundthis: “Accordingto the von Mises’stheory,aductile solidwill yieldwhenthe distortionenergy densityreachesacritical value forthat material …At the instance of yieldinginauniaxial tensile test,the state of stressintermsof principal stressisgivenby:σ1= σY (yieldstress) andσ2= σ3 = 0.” (http://web.mae.ufl.edu) Essentiallythisissayingthat,if 𝜎1, 𝜎2 and 𝜎3 are the stresslevelsinthe planes 𝑥, 𝑦and 𝑧,thenwhen the stresslevel inthe 𝑥 plane isequal tothe yieldstressof the material then the stressesinthe othertwo planesare zero.Fromthiswe can saythat the VonMisesstressesare a measure of the level of stressina3D plane inrelationtothe yieldstressof the material. Figure 1: HoneycombModel.
- 3. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 3 of 9 To testthe honeycombstructure Isetthe meshsize to5mm. From here I startedwith compressioninthe L plane.Isetclampson the bottomrow of the structure at the lowestpoint available,therewere 20clampsusedto ensure thatthe whole structure wascovered.Thenthe load was appliedtothe toprow onthe highestpointsavailable,there were also20load points.However due to the staggerednature of the honeycombthe loadswere notdirectlyabove the clampsso there wouldbe anoffsetinthe motionincompressing the honeycomb.One possibleway roundthis wouldbe to adda plate tothe topand bottomof the honeycombandplace loadsandclampson that instead,butthenthisstructure wouldalsohave tobe accountedfor. Once the loadsand clampswere inplace I startedwitha loadof 100N and recordedthe Von Misesstress,here Ichose to go for an average stresslevelswhenlookingatthe model,Ialsodecided to findthe cell withthe maximumstressandrecordthatvalue.The max stressturnedout to be in the lowerleftcorner,thiswasexpecteddue tothe offsetinpositionof the clampsandloads. Table of loadsin the L direction. Load Weight Average VonMisesStress Higheststressedcell 100N 1.37𝑒6 𝑁𝑚2 2.54𝑒6 𝑁𝑚2 200N 2.74𝑒6 𝑁𝑚2 5.08𝑒6 𝑁𝑚2 300N 4.11𝑒6 𝑁𝑚2 7.62𝑒6 𝑁𝑚2 400N 5.48𝑒6 𝑁𝑚2 1.02𝑒7 𝑁𝑚2 500N 6.85𝑒6 𝑁𝑚2 1.27𝑒7 𝑁𝑚2 600N 8.22𝑒6 𝑁𝑚2 1.52𝑒7 𝑁𝑚2 700N 9.59𝑒6 𝑁𝑚2 1.78𝑒7 𝑁𝑚2 800N 1.10𝑒7 𝑁𝑚2 2.03𝑒7 𝑁𝑚2 900N 1.23𝑒7 𝑁𝑚2 2.29𝑒7 𝑁𝑚2 1000N 1.37𝑒7 𝑁𝑚2 2.54𝑒7 𝑁𝑚2 1100N 1.51𝑒7 𝑁𝑚2 2.79𝑒7 𝑁𝑚2 1200N 1.64𝑒7 𝑁𝑚2 3.05𝑒7 𝑁𝑚2 1300N 1.78𝑒7 𝑁𝑚2 3.30𝑒7 𝑁𝑚2 1400N 1.92𝑒7 𝑁𝑚2 3.56𝑒7 𝑁𝑚2 1500N 2.06𝑒7 𝑁𝑚2 3.81𝑒7 𝑁𝑚2 1600N 2.19𝑒7 𝑁𝑚2 4.07𝑒7 𝑁𝑚2 1700N 2.33𝑒7 𝑁𝑚2 4.32𝑒7 𝑁𝑚2 1800N 2.47𝑒7 𝑁𝑚2 4.57𝑒7 𝑁𝑚2 1900N 2.60𝑒7 𝑁𝑚2 4.83𝑒7 𝑁𝑚2 2000N 2.74𝑒7 𝑁𝑚2 5.08𝑒7 𝑁𝑚2 The structure hadnot failedat2000N, but itwas severelycompressedatthispoint.The compression wouldhave ledtothe part beingunusable atthisload. For testingthe W directionIdecidedtohave the leftside of the honeycombasmyloadpointand the right side asthe clamp point,Iusedthe same methodas withthe loadinginthe L direction. Average VonMisesStresstable forloadsinthe W direction.
- 4. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 4 of 9 Load Weight Average VonMisesStress Higheststressedcell 100N 1.68𝑒6 𝑁𝑚2 3.34𝑒6 𝑁𝑚2 200N 3.36𝑒6 𝑁𝑚2 6.68𝑒6 𝑁𝑚2 300N 5.04𝑒6 𝑁𝑚2 1.00𝑒7 𝑁𝑚2 400N 6.72𝑒6 𝑁𝑚2 1.34𝑒7 𝑁𝑚2 500N 8.40𝑒6 𝑁𝑚2 1.67𝑒7 𝑁𝑚2 600N 1.01𝑒7 𝑁𝑚2 2.00𝑒7 𝑁𝑚2 700N 1.18𝑒7 𝑁𝑚2 2.34𝑒7 𝑁𝑚2 800N 1.34𝑒7 𝑁𝑚2 2.67𝑒7 𝑁𝑚2 900N 1.51𝑒7 𝑁𝑚2 3.01𝑒7 𝑁𝑚2 1000N 1.68𝑒7 𝑁𝑚2 3.34𝑒7 𝑁𝑚2 1100N 1.85𝑒7 𝑁𝑚2 3.67𝑒7 𝑁𝑚2 1200N 2.02𝑒7 𝑁𝑚2 4.01𝑒7 𝑁𝑚2 1300N 2.18𝑒7 𝑁𝑚2 4.34𝑒7 𝑁𝑚2 1400N 2.35𝑒7 𝑁𝑚2 4.68𝑒7 𝑁𝑚2 1500N 2.52𝑒7 𝑁𝑚2 5.01𝑒7 𝑁𝑚2 1600N (*) 2.69𝑒7 𝑁𝑚2 5.34𝑒7 𝑁𝑚2 1700N 2.86𝑒7 𝑁𝑚2 5.68𝑒7 𝑁𝑚2 1800N 3.02𝑒7 𝑁𝑚2 6.08𝑒7 𝑁𝑚2 1900N 3.19𝑒7 𝑁𝑚2 6.35𝑒7 𝑁𝑚2 2000N 3.36𝑒7 𝑁𝑚2 6.68𝑒7 𝑁𝑚2 (*) Atthispointthe structure collapsed,forcomparisonhoweverIcontinuedtoincrease the loadsso that I couldcompare the stresslevels inbothdirections. Since a table witha listof numberscan sometimesbe hardto analyse Ihave decidedtoplotthe informationintoagraph. As we can see fromthe chart, the stresslevelsare higherinthe Wplane than inthe L plane,alsothe maximumstressesare alsorespectivelyhigher.Asstatedinthe table forthe W plane the structure 0 10 20 30 40 50 60 70 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 VonMisesStress(×e6Nm2) Load (N) Von Mises Stress in both L and W planes Avg. Stress L Plane Max Stress L Plane Avg. Stress W Plane Max Stress W Plane
- 5. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 5 of 9 failedat1600N but I continuedwiththe analysistocompare the twoplansaccurately.Itcan be seen that the stresslevelsare proportionaltothe loads. “ StevenKendell’sTests: “Finite ElementAnalysis To analyse the Honeycombmodel,IusedCATIA generativestructural analysisfeature.Before submittingmymodel intoFEA,Idefinedthe material propertiesfollowingthe specificationthatwas given.Totestthe honeycombstructure Isetthe meshsize to5mm. Firstof all I testedthe model in the L plane,placingloadsoneachof the 20 verticesonthe toprow of the honeycomb,Ithenset clampson the bottomrow. There wasa slightoffsetdue tothe staggerednature of the Model.I foundthe average andmaximumdisplacementof the honeycombatdifferentloads.The loadedand restrainedmodel isshowninFigure 2. Anothermaterial wasalsotested,“Aluminiumhoneycombis available infourdifferentalloys, aerospace grades5052 and5056, and commercial grades3104 and 3003.” (http://www.hexcel.com 10/12/15) The material Ichose to compare withAluminium3003 was Aluminium5056. The Physical properties of thisalloywasfoundusingthe MatWeb:Online MaterialsInformationResource.Figure3 highlightsthe physical propertiesthatwere necessarytocompute the analysis. Figure 2: Loadedand RestrainedModel.
- 6. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 6 of 9 The difference inYieldstrengthwill allow forananalysisof the Honeycombswhere thereisa difference inthe plasticity. (http://www.matweb.com 10/12/15) The resultsof the finite elementanalysisof Aluminium3003 showedthatthe average andmaximum Vonmisesstresswas constantfor a given load,and wasnot dependantonthe aluminiumalloy.We founda linear relationshipbetweenVonmisesstressandthe force appliedtothe structure,the steepnessof the curve showsthe amountof stressexperiencedbythe model perLoadapplied.Figure4showsthat the curve withthe steepestgradientwasforthe max stressexperiencedbythe model whenthe load was appliedinthe Wdirection.Therefore,the model will experience plasticdeformationundera smallerloadthanif the loadwas appliedinthe L plane. The resultsthatoccurredfor Aluminium5052 were identical tothatof Aluminium3003, however the yieldstrengthof Aluminium5052 is 90MPa. Therefore a much greaterloadcan be appliedtothe honeycombbefore plasticdeformation takesplace. Youngs Modulus Yield Strength Aluminium 3003 69GPa 40MPa Aluminium 5056 71.0GPa 150MPa Figure 3: Physical Propertiesof AluminiumAlloys usedinAnalysis. FIGURE 4 FIGURE 5
- 7. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 7 of 9 AbhishekDabas’s Results: Here are the resultsthatDean hasgathered. LAVG LMAX WAVG WMAX 100 1.08 2.15 3.21 6.42 200 2.15 4.3 6.43 12.9 300 3.23 6.45 9.64 19.3 400 4.3 8.6 12.9 25.7 500 5.38 10.8 16.1 32.1 600 6.46 12.9 19.3 38.5 700 7.53 15.1 22.5 44.9 800 8.61 17.2 25.7 51.4 900 9.68 19.4 28.9 57.8 1000 10.8 21.5 32.1 64.2 1100 11.8 23.7 35.3 70.6 1200 12.9 25.8 38.5 77 1300 14 28 41.8 83.5 1400 15.1 30.1 45 89.9 1500 16.1 32.3 48.2 96.3 1600 17.2 34.4 51.4 103 1700 18.3 36.6 54.6 109 1800 19.4 38.7 57.8 116 1900 20.4 40.9 61 122 2000 21.5 43 64.2 128 0 20 40 60 80 100 120 140 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 VonMises(MPa) Loads (N) Von Mises Stress (Dean) Avg Von Mises L Direction Max Von Mises L Direction Avg Von Mises W Direction Max Von Mises W Direction
- 8. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 8 of 9 As youcan see the graph showsthat there isa linearrelationbetweenloadandVonMisesstress levels. Comparisonof the FEA’s The four differentsetsof dataallow usto make a strongcomparisonbetweenthe loadand the VonMisesstressvalues.Althoughthe testswere carriedoutbydifferentpeopleindifferent waysand had the unitsgivenindifferentways,we cansaythat there isdefinitelyalinearrelation betweenthe Loadandthe comparative VonMisesstress.Each of the graphs show a roughlystraight line increasingfromlefttoright,since eachof the graphsshow the same linearpatternwe can conclude thatthe data gatheredare consistentatleastwitheachother. Startingwiththe L plane,we canconclude thatfor everyXnewtonloadamountthere will be a correspondingYvalue forthe VonMisesstress,thisvalue will be inthe formof Y=mX+c where bothm and c are constantsfor the equation butwhenthe loadisa 0N the stresslevel will be a0 as well therefore we canconclude thatc has a value of 0. Infact thisequation 𝑦 = 𝑚𝑥+ 𝑐 holdstrue for eachsetof data gathered,the onlydifference isinthe valuesof m,since c will alwaysbe 0when the loadis at 0N. It can be seenfromthe graphsthat the value form increasesaslookat different parts of the data,hence the graph. The bottomline inthe graph showsthe valuesforthe L plane at an average value forVonMisesstress,the secondline showsvaluesforthe L plane butthistime at the max value forVonMisesstress.The thirdline shows,however,the valuesforthe Wplane at the average value forVonMisesstressandthe fourthshowsthe valuesforthe W plane at the max value for VonMisesstress.Here we mustnote that there isa difference inthe gradientof the line forthe W plane comparedto the L plane inboth the average valuesandthe max valuesof VonMisesstress. In notingthiswe can begin tosay that there islessstructural stabilityinthe Wplane thaninthe L plane,thiscanbe saidbecause itcan clearlybe seenthatthere are higherstressvaluesinthe W plane comparedtothe L plane.The reasonforthe lowerstructural stabilitycouldbe inthe factthat inthe L plane the vertical wallshave athicknessof 0.2mmwhereasinthe W plane the corresponding“vertical”wallsonlyhave athicknessof 0.1mm. There are waysthat we couldoptimise thisdesignbothinthe testingof the designandinits complete state.Firstlyfortestingwe couldaffix platestothe topand bottom, or to the leftandright handsides,of the structure and use those to fullydistribute the weightacrossthe whole structure, but the downside tothispotentialmethodwouldbe thatthiswouldcause anincrease inthe weight of the structure and itsstability,the ideabehindthe honeycombstructure isthatitislightweight and flexibleinthe Land W planesbutrigidinthe T plane. Inthe designof the honeycombwe could make all vertical wallsineitherdirection0.2mmratherthanjust inthe L plane.Idon’tthinkthis wouldseriouslyincreasethe weightof the objectandit wouldgive comparable strengthinin compressioninboththe L plane andin the W plane. In Conclusion: Althougheachmemberof the groupcame at the task withdifferentideasandskillsetswe have all foundthat we have learnedsomethingnew whilstdoingthisproject.We managedtocreate a workinghoneycombstructure andwe all managedtotestit inFEA. Althoughourmethodsof creatingand testingwere differentwe foundthatthe resultsthatwe eachobtainedwere comparable whichwouldsuggestthatthe resultswere eitherthe same orsimilarenough. Onthe downside thoughwe were hopingtohave enoughtime tooptimisethe designandcreate abetter honeycombthanwhenwe started,butwithillnessesandpeopledroppingoutwe foundourselves
- 9. CAD Report 104AAEGroup Members: Adam Rush, Steven Kendell, Abhishek Dabas Page 9 of 9 out of time to do the optimisation,butwe canlearnfromthisfor the nextprojectthat we come to as a group. References: http://web.mae.ufl.edu: http://web.mae.ufl.edu/nkim/eas4200c/VonMisesCriterion.pdf (04/12/15) http://www.autodesk.com:http://www.autodesk.com/solutions/finite-element-analysis(10/12/15) http://www.hexcel.com:http://www.hexcel.com/Resources/DataSheets/Brochure-Data- Sheets/Honeycomb_Attributes_and_Properties.pdf (10/12/15) http://www.matweb.com:http://www.matweb.com/search/datasheet.aspx?matguid=aaaabe41a20 a4ed2b48270f7f2ef1b2d (10/12/15)