vdi2230-螺栓计算

OverviewofVDI2230 AnIntroductiontotheCalculationMethodforDeterminingtheStressinaBoltedJoint ImportantNote ThissummaryoftheVDI2230Standardisintendedtoprovideabasicunderstandingofthemethod Readerswhowishtoputthestandardtouseareurgedtorefertothecompletestandardthatcontainsallinformation figures etc Definitions Covershigh dutyboltedjointswithconstantoralternatingloadsBoltedjointsareseparablejointsbetweentwoormorecomponentsusingoneormoreboltsJointmustfulfillitsfunctionandwithstandworkingload AimofCalculation Determineboltdimensionallowingfor StrengthgradeoftheboltReductionofpreloadbyworkingloadReductionofpreloadbyembeddingScatterofpreloadduringtighteningFatiguestrengthunderanalternatingloadCompressivestressonclampedparts 1 RangeofValidity SteelBoltsM4toM39RoomTemperature 2 ChoiceofCalculationApproach DependentupongeometryCylindricalsingleboltedjointBeamconnectionCircularplateRotationofflangesFlangedjointwithplanebearingface CylindricalSingleBoltedJoint Axialforce FATransverseforce FQBendingmoment MB BeamGeometry Ex 1 Axialforce FATransverseforce FQMomentoftheplaneofthebeam MZ BeamGeometry Ex 2 Axialforce FATransverseforce FQMomentoftheplaneofthebeam MZ RotationofFlanges Axialforce FA pipeforce Bendingmoment MBInternalpressure p FlangedJointwithPlaneBearingFace Ex 1 Axialforce FA pipeforce Torsionalmoment MTMoment MB FlangedJointwithPlaneBearingFace Ex 2 Axialforce FA pipeforce Transverseforce FQTorsionalmoment MTMoment MB FlangedJointwithPlaneBearingFace Ex 3 Axialforce FA pipeforce Transverseforce FQTorsionalmoment MTMoment MB 3 AnalysisofForceandDeformation Optimizedbymeansofthoroughandexactconsiderationofforcesanddeformationsincluding ElasticresilienceofboltandpartsLoadanddeformationratioforpartsinassembledstateandoperatingstate 4 CalculationSteps Beginswithexternalworkingload FBWorkingloadandelasticdeformationsmaycause Axialforce FATransverseforce FQBendingMoment MBTorquemoment MT DeterminingBoltDimensions Onceworkingloadconditionsareknownallowfor LossofpreloadtoembeddingAssemblypreloadreducedbyproportionofaxialboltforceNecessaryminimumclamploadinthejointPreloadscatterduetoassemblymethod CalculationStepR1 Estimationofboltdiameter dEstimationofclampinglengthratio lK dEstimationofmeansurfacepressureunderboltheadornutarea pGIfpGisexceeded jointmustbemodifiedandlK dre determined CalculationStepR2 Determinationoftighteningfactor aA allowingfor AssemblymethodStateoflubricationSurfacecondition CalculationStepR3 Determinationofrequiredaverageclampingload Fkerf aseither Clampingforceontheopeningedgewitheccentricallyactingaxialforce FAOrClampingforcetoabsorbmomentMTortransverseforcecomponent FQ CalculationStepR4 Determinationofloadfactor F including Determinationofelasticresilienceofbolt dSEvaluationofthepositionofloadintroduction n lKDeterminationofelasticresilienceofclampedparts dPCalculationofrequiredsubstitutionalcross section Aers CalculationStepR5 Determinationoflossofpreload FZ duetoembeddingDeterminationoftotalembedding CalculationStepR6 DeterminationofboltsizeandgradeFortighteningwithintheelasticrange selectboltforwhichinitialclampingloadisequaltoorgreaterthanmaximuminitialclampingloadduetoscatterinassemblyprocessFortighteningtoyield selectboltforwhich90 ofinitialclampingloadisequaltoorgreaterthanminimuminitialclampingloadduetoscatterinassemblyprocess CalculationStepR7 Ifchangesinboltorclampinglengthratio lK d arenecessary repeatStepsR4throughR6 CalculationStepR8 Checkthatmaximumpermissibleboltforceisnotexceeded CalculationStepR9 DeterminealternatingstressenduranceofboltAllowforbendingstressineccentricloadapplicationsObtainapproximatevalueforpermissiblestressdeviationfromtablesIfnotsatisfactory useboltwithlargerdiameterorgreaterendurancelimitConsiderbendingstressforeccentricloading CalculationStepR10 ChecksurfacepressureunderboltheadandnutbearingareaAllowforchamferingofholeindeterminingbearingareaTablesproviderecommendationsformaximumallowablesurfacepressureIfusingtighteningtoorbeyondyield modifycalculation 5 InfluencingFactors Allowforfactorsdependingupon MaterialandsurfacedesignofclampedpartsShapeofselectedboltsandnutsAssemblyconditions StrengthoftheBolt Stresscausedby TorsionalandaxialstressesduringtighteningWorkingloadShouldnotexceedyieldload MinimumThreadEngagement Dependsupon Threadform pitch tolerance anddiameterFormofthenut wrenchingwidth BoltholeStrengthandductilityofboltandnutmaterialsTypeofstress tensile torsional bending FrictioncoefficientsNumberoftightenings ThreadShearStrength Bolt NutStrengthMatchingNumberforstrengthgradeofnutisequivalenttofirstnumberofstrengthgradeofbolt CalculationofRequiredNutHeight AllowsforgeometryandmechanicalpropertiesofjointelementsPredictstypeoffailurecausedbyoverloadingConsiders Dimensionalvalues tensilecross sectionofboltthread threadengagementlength etc Threadform nutformBoltclearancehole BoltHeadHeight EnsuresthatfailurewilloccurinfreeloadedthreadsectionorintheshankHighesttensilestressinthread Highesttensilestressinbolthead SurfacePressureatBoltHead NutBearingAreas CalculationdeterminessurfacepressurecapableofcausingcreepresultinginlossofpreloadSurfacepressureduetomaximumloadshouldnotexceedcompressiveyieldpointofclampedmaterial TighteningFactor AlphaA Allowancemustbemadefortorsionalstresscausedbypitchandthreadfriction andaxialtensilestressScatterinfrictioncoefficientsanderrorsinmethodofcontrollingpreloadcreateuncertaintyinleveloftensileandtorsionalstressTighteningfactor aA reflectsamountofrequired over design FatigueStrength DesignmodificationstoimproveendurancelimitofjointIncreasepreloadReducepitchofscrewthreadReductionofmodulusofnutmaterialelasticityIncreasethreadengagement FatigueStrength Continued Designmo