©2011ANSYS,Inc. July5,20161

ModellingthePerformance&DurabilityofWeldswithANSYS&nCode

©2011ANSYS,Inc. July5,20162

Agenda•  OverviewofWeldingonFaBgue

•  DefiniBonofStressMeasuresforSeamWelds

•  SeamWeldAnalysisMethods– Volvo/ChalmersMethod– ASMEBoiler&PressureVesselCodeVIII,Div2.– BS7608,AWS,EurocodeExamples:– Flatplatetransversefilletweld– TubularpipeintersecBonweldedjoint– VibraBonfaBgueofaweldedtransformermounBngbracket

©2011ANSYS,Inc. July5,20163

EffectofWeldingonDurability

Parent plate Fusion zone Heat affected zone

Weld toe

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Volvo/Chalmers/nCodemethod

E(i)

E(j)

σ⊥Α

σ⊥Β

sheet B

sheet A

tB

t A

effective throat, a

•  Sheetsandweldsmodeledpredominantlywithrectangular4or8nodedshells

•  Sheetsdescribedbymeansurfaces•  ThicknessofweldelementsequalseffecBvethroat,or

around2xsheetthickness•  Elementlengthofabout5mm•  Smallradiinotmodeled

©2011ANSYS,Inc. July5,20165

Damageparameter(stress)definiBon

DamageparameterisusuallyeithertheAbsMaxPrincipalstressorCriBcalPlanestressatweldtoe

Stressescanbedeterminedbasedoneither:

•  Forcesandmomentsatnodesalongweldtoe

•  ThenodaldisplacementsandrotaBonsoftheweldtoeelements

Forces/moments > Stresses

Displacement/rotaBon>Strains > Stresses

©2011ANSYS,Inc. July5,20166

DamageStressCalculaBon

σtop

σbot

σtop

σbot (insamedirec@onasσtop)

AbsMaxPrincipalexample

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SN curve interpolation using bending stress ratio

“flexible”orbendingloadingcondiBons(r=1)“sBff”ormembraneloadingcondiBons(r=0)

Flexiblejointshavemorebendingatweldtoe

SBffjointshavelowerfaBguestrength

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Structural stress history and bending stress ratio calculated at weld location

•  CalculatethestresstensorateachpointalongtheStressClassificaBonLine(SCL)byinterpolaBonofthefiniteelementnodalnormalstresses(σxxi,σyyi,σzzi, τxyi, τyzi, τxzi)definedintheglobalX,Y,Zaxes

•  TransformthestresstensortotheweldlinereferencesystemdefinedbyVt,VeandVn.ThestresscomponentsintheplaneperpendiculartoVnareσf,σee,andτte

•  Calculatemembrane(σf,m,σee,m,τte,m)andbending(σf,b,σee,b,τte,b)stressesintheVt/Veplane

•  Calculatethemembraneandbendingstressesonthetopandbofomsurfaces

Top BoGom

©2011ANSYS,Inc. July5,20169

Tubularweldedjoint•  TwocircularintersecBngpipes,solidseamweldcomparisonwith

experimentalresults

CourtesyG.MenegheO,DepartmentofMechanicalEngineering,UniversityofPadova,viaVenezia1–35131Padova(Italy)

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