服裝導購必須知道的銷售技巧四第1頁/共25頁ProjectObjectivesDesignandbuildatorsiontestingmachinecapableofperformingtheASTMTorsionTestMachinemustmeasurematerialpropertiestowithin5%ofpublisheddataMachinemustbeaffordable第2頁/共25頁TorsionTestingApparatusExperimentallydeterminestorsionalshearpropertiesofmaterialsAcylindricaltestspecimenistwisteduntilfailureAppliedtorqueandangleoftwistarerecordedASTMStandardizedTestMethodUsed

-SpecifiesTestProcedure/SpecimenGeometry第3頁/共25頁DesignConstraintsMachinemustbecapableoffracturingasteeltestspecimenSpecimendiametertobe3/8inchtoallowexaminationoffracturesurfaces

-ASTMthereforerequiresaspecimenlengthof

6inchestomeettheminlength/diameterratioTorqueandangleoftwistmeasuringdevicestobeeasilyaccessibletostudents第4頁/共25頁DesignConstraintsMachinemustproducemeasurementswithin5%ofpublishedASTMresultsBudgetallocationof$500ManyYearsofService!!!第5頁/共25頁DeterminationofShearProperties

Elementarymechanicstheoryusedtorelate

appliedtorque,Ttoshearstress,τ

using

Eq.(1)whereρ=radiusofthespecimencrosssection

J=polarmomentofinertiaofcrosssection

Shearstrainγiscalculatedusing

Eq.(2)

γ

=ρθ/L

whereL=specimenlength

θ=angleoftwist第6頁/共25頁DeterminationofShearPropertiesShearModulusGisdeterminedbyfindingtheslopeofthesheartress-straindiagramShearmodulusmayalsobecalculatedusingEq.(3)第7頁/共25頁Design–TorqueandAngleofTwistRequirementsEquation(1)wasusedtoestimatethetorquerequiredtoyieldaC1018planecarbonsteeltestspecimenintorsion3000in-lbwouldberequiredtofailC1018materialatconstantrotationalvelocityExperimentswereperformedusingaluminumtofindrequiredangleoftwist(10revolutions)第8頁/共25頁DesignLayout第9頁/共25頁DriveTrain

ADCmotorwithanintegralgearreductionandspeed

controllerwasusedAsprocketsethavinga6:1gearratiodevelopedrequired

torque第10頁/共25頁FrameDesignBaseFrame/MotorSubAssembly

Twoinchsquaresteelchannelwaswelded

togethertoformtheframe第11頁/共25頁Gagemountedona45°AngleTorqueGageMeasurementofTorque

Atorquegaugewasfittedtothe

fixedhub第12頁/共25頁MeasurementofTorqueσ(kpsi)

(kpsi)σ2=σ1=2?

StrainGaugealignedwithdirectionofMaxPrinciple

Stress45°maxσ1σ2StateofPureShear第13頁/共25頁MeasurementofAngleofTwistPotentiometerWeightWheelSprocket

Apotentiometerwasmountedtoawheel

whichcontactedtherotatinghub.第14頁/共25頁ChuckAlignment

AT-slidewasusedtopreventdevelopment

ofaxialloadsandtoaidinalignment第15頁/共25頁TorqueCalibrationFabricatedTorqueWrenchGage

Aweightedleversystemwasusedtocalibrate

thetorquegauge第16頁/共25頁TorqueCalibrationCurve第17頁/共25頁CompleteAssemblyPotentiometerLeadsMotorSpeedControlPowerSwitches/LEDsStrainGaugeLeads第18頁/共25頁PerformanceDataCollectionwithLabVIEWTestingof1018ColdDrawnSteelShearmodulusmeasuredas10.7Mpsi,3%lowerthanthepublishedvalueTestingof2014AluminumShearmodulusmeasuredas3.7Mpsi,5%lowerthanthepublishedvalue第19頁/共25頁BudgetAnalysisItemDescriptionManufacturerMfg.#VendorVendor#QuantityCostEa.($)TotalCost($)

DCMotorDayton4Z530Grainger4Z5311258258DCSpeedControlDartControls125DV-C-KGrainger2M510177772inchSprocketUSTsubaki50B9FGrainger6L9271111112inchSprocketBrowning50Q60Grainger1L21319393Chain(10feet)USTsubaki50TW10Grainger2W09513434PotentiometerEITMW22B-10-2KNewarkInOne83H756811010DrillChuckJacobs30602McMaster3094A1721938NeonLampAssemblyRadioShack2720712RadioShack2720712144NeonLampAssemblyRadioShack2720708RadioShack2720708144DualBindingPostRadioShack2740718RadioShack2740718155

FinalCost($)534第20頁/共25頁IntegrationIntotheMECurriculumTorsionmachinehasbeenintegratedintwoways

-ASTMtorsionexperimenthasbeen

includedinthejuniorlaboratorysequence

-designanduseofthetorsionmachineis

introducedinthesophomoreMechanicsof

Materialscourse第21頁/共25頁JuniorLaboratoryExperienceStudentsexaminethetorquecellandcalculateitslimitingtorsionalstrengthStudentscreatecalibrationcurvesforthetorquecellandrotationalpotentiometerSteelandaluminumspecimensaretestedofailureandtheresultsarecomparedtopublisheddata第22頁/共25頁MechanicsofMaterialsCourseStudentsexaminethetorquecellandcalculateitslimitingtorsionalst