fea sample

Download FEA SAMPLE

Post on 21-Aug-2015

27 views

Category:

Documents

1 download

Embed Size (px)

TRANSCRIPT

  1. 1. 1 MECH4175 Project2 KeithBenedix
  2. 2. 2 Introduction SolidWorkswasusedtoexaminetheresidualVonMisesstressesina2006BurtonFreestyle snowboard binding (shown on the cover). In order to model the assembly in the program, someminoradjustmentsneededtobemadetothematerialbeingtested.Theactualbindingis madeofacompositecalledNylon6/630%glass-fiberreinforced(Nylon6/6GF30)toimprove mechanicalperformanceintoughnessandabrasionresistance.Thisnylonvarianthasbeen known to exhibit increased structural and impact strength, and rigidity. The addition of glassfiberstonylon6/6invariousamounts(10%,20%,30%and40%)increasestensile strength,stiffness,compressivestrength,andalowerthermalexpansioncoefficientover conventional unfilled grades. Glass filled nylons offer better strength than general purpose nylon but it is highly abrasive and will abrade or gall mating surfaces. (Emco Industrial Plastics, Inc.). Since Solid Works does not include this material in its material calendar,Nylon6/10wasusedinsteadtoobtainthemostaccurateresults.Figure1isatable comparingthemechanicalpropertiesofthethreematerials. Mechanical Property Nylon6/6 Nylon6/6GF30 Nylon6/10 TensileStrength [psi] 12,400 27,000 8,700 Elongation[%] 90 3 90 FlexuralStrength [psi] 17,000 39,100 11,000 FlexuralModulus [psi] 4.1e5 12e5 2.9e5 RockwellHardness [ft-lb/in] 1.2 2.1 -- Figure1:MechanicalPropertiesofNylon6/6,Nylon6/630GF,andNylon6/10(takenfromPlasticProducts,Inc.)
  3. 3. 3 Ascanbeseeninthetable,Nylon6/10isweakerthanNylon6/6andsignificantlyweakerthan Nylon6/6GF30.ThisjustmeansthattheresultsintheFEAwillbeextremelyconservative comparedtotherealworldmodel. The assembled model only consists of three parts. This was done in Solid Works with the intentionofdoingananalysisontheassembly,butunfortunatelywhenattempted,theanalysis eitherfailedorgaveinaccurateresults.Thisprobablyhadalottodowiththewaytheassembly wasconstrainedandtheflexuralmodulusofthematerial.Instead,eachpertinentpartinthe assembly (namely the base plate and the high back) was tested individually to get accurate results.Figure2isanexplodedviewoftheassemblyforthepurposeofshowingthenameof eachpart. Figure2:ExplodedViewoftheBinding HighBack LockDisk BasePlate
  4. 4. 4 Itshouldbenotedthattheheelandtoestrapswerenotincludedinthismodelduetothefact thatthemotivationinthissimulationwastoonlyanalyzethepartsofthebindingthatwould breakafterexperiencinghighimpact(i.e.landingflatfromahighdrop).Insuchcases,itwould beunusualforthebindingstrapstoexperienceanysignificantforcesatall. Methods Previously,welearnedthatthemeshandrunmethodwasadecentwaytogetanumerical valueasastartingpoint,butwasinaccurateinpractice.So,thismethodwasdroppedandthe h-adaptiveandp-adaptivemethodswereusedtoruntheFEAonthebaseplateandhighback ofthebinding.Thebaseplatewasloadedatthecruxofwhatisknownastheheelcuffwithan externalverticalforceof1000lbs.andfixedonthebottomsurface.Thep-adaptivemethodwas runfirst,butprovedtobeinconclusiveasitsassociatedconvergencegraphinFigure3showed noplateau. 19000 20000 21000 22000 23000 24000 25000 26000 27000 28000 29000 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 VonMisesStress[psi] LoopNumber Figure3:MaximumVonMisesonBaseplateUsingtheP-AdapXveMethod
  5. 5. 5 Theres nothing particularly interesting about this plot, only the fact that the method used proved to give inconclusive results. The h-adaptive method did, however, yield accurate results.Figure4showstheconvergencegraphwhentheh-adaptivemethodwasused. Ascanbeseenbytheplotabove,themethodconvergesandwehaveanaccuratereadoutin thesimulationofthemaximumVonMisesstressbeingaround32,000psiafteronlythethirdof thefiveloopsthatthesimulatorruns.Moreover,ascreenshotoftheresultsintheSolidWorks Simulator(depictedinFigure5)showswherethebaseplatemightfail.WecanseeinFigure5 thattheredoesntseemtobeanysignificantareathatexperiencesanystressabovetheyield stress.Giventheloadingconditions,itisapparentthatthebaseplateofthisbindingissafein themostextremecase,giventhattheaverageAmericanmalehasamassof75kg.andwould notlikelyloadthebindinginsuchaway. 15000 17000 19000 21000 23000 25000 27000 29000 31000 33000 0 0.5 1 1.5 2 2.5 3 VonMisesStress[psi] LoopNumber Figure4:MaximumVonMisesonBaseplateUsingtheH-AdapXveMethod
  6. 6. 6 Figure5:ResultsofH-AdaptiveMethodAnalysisinSolidWorksSimulator Thehighbackwasloadedalittledifferentlythanthebaseplatebecauseofnumerouslarge displacementfailures.Aloadof100lbs.wasappliedtothefrontface(wherethebackofa ridersbootwouldmakecontact)andfixedwhereitmakesitsassemblyconnectionandwhere itrestsontheheelcuffofthebaseplate.Figure6istheconvergencegraphfortheanalysisin whichthep-adaptivemethodwasutilized. 400 450 500 550 600 650 700 750 1 1.5 2 2.5 3 3.5 4 VonMisesStress[psi] LoopNumber Figure6:MaximumVonMisesonHighBackUsingtheP-AdapXveMethod
  7. 7. 7 Figure6showsthatthep-adaptivemethodwasabletoshowconvergence,andsoitislikely that the results are accurate. Figure 7 is a screen shot of the results in the Solid Works Simulator. Figure7:ResultsofP-AdaptiveMethodinSolidWorksSimulator Accordingtothereadoutthepartdoesnotyieldwiththegivenloadingconditions.Thistime, theh-adaptivemethodwastheonethatdidnotconverge.Figure8isthedivergingplotofthe results from the h-adaptive method for this part. Again, there is nothing interesting about Figure8,onlythattheh-adaptivemethodhasproventohaveaninconclusiveresult.Itshould benoted,however,thatitisquitecuriousthatforbothpartsonlyoneofeitherofthetwo methodsgavegoodresults.Inthepast,eitherbothweredivergentorconvergentwhenthe plotswerelookedat.Also,uponcomparisonwiththemeshandruncaseforthispart(shown inFigure9),wecanseethattheresultsarereallynotthatfarapartfromeachother.
  8. 8. 8 Figure8:ResultsofMeshandRunMethodinSolidWorksSimulator 0 500 1000 1500 2000 2500 3000 0 0.5 1 1.5 2 2.5 3 3.5 4 VonMisesStress[psi] LoopNumber Figure8:MaximumVonMisesonHighBackUsingtheH-AdapXveMethod
  9. 9. 9 Discussion Insummary,thispartissafetouseonasnowboard(whichitshouldbe).Themainpartsthat wouldtakealloftheappliedloadsinarealworldsituationdontseemtomeetthefailcriteria. FEAwasusedandbackedupbythreedifferentmethods:themeshandrun(asanestimate), thep-adaptive,andtheh-adaptive.Inthepast,ithasbeenseenthattheh-adaptivemethod wasthemostaccuratewaytoobtaindesiredresults.Inlightofthismostrecentstudy,itseems thattheconvergencegraphsoneithermethodusedareagoodwaytoprovethattheresults thatthesimulatorgivesareaccurate.Figure9isasummaryofalltheresultsfoundinthis analysis. Method VMStressonBasePlate[psi] VMStressonHighBack[psi] MeshandRun 17,975 564.4 P-Adaptive -- 726.9 H-Adaptive 32,171.6 -- Figure9:SummaryofAllResultsforProject2