8. Adhesive Bonding and Integrally Cocured Structure.pdf

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1、Chapter8AdhesiveBondingandIntegrallyCocuredStructureManufacturingTechnologyforAerospaceStructuralMaterialsAdhesivebondingisamethodofjoiningstructuretogetherthateliminatessome,orall,ofthecostandweightofmechanicalfasteners.Inadhesivebonding,curedcompositesormeta

2、lsareadhesivelybondedtoothercuredcomposites,honeycombcore,foamcore,ormetallicpieces.Cocuringisaprocessinwhichuncuredcompositepliesarecuredandbondedsimultaneouslyduringthesamecurecycletoeithercorematerialsorothercompositeparts.Theabilitytomakelargebondedandcocu

3、redunitizedstructurecaneliminateasignificantportionoftheassemblycosts.Adhesivebondingisawidelyusedindustrialjoiningprocessinwhichapoly-mericmaterial(theadhesive)isusedtojointwoseparatepieces(theadherendsorsubstrates).Therearemanytypesofadhesives;somearestronga

4、ndrigidwhileothersareweakandflexible.Adhesivesusedforstructuralbondingarealwayscuredateitherroomorelevatedtemperaturesandmustpossessadequatestrengthtotransfertheloadsthroughthejoint.Therearemanytypesofstruc-turaladhesives;however,epoxies,nitrilephenolics,andbi

5、smaleimidesarethemostprevalent.Inadditiontofabricatinglargebondedcomponents,adhesivebondingisfrequentlyusedforrepairingdamagedstructuralparts.Bondedjointsmaybepreferredifthincompositesectionsaretobejoinedwherebearingstressesinboltedjointswouldbeunacceptablyhig

6、h,orwhentheweightpenaltyformechanicalfastenersistoohigh.Ingeneral,thinstructureswithwell-definedloadpathsaregoodcandidatesforadhesivebonding,whilethickerstructureswithcomplexloadpathsarebettercandidatesformechanicalfastening.18.1AdvantagesofAdhesiveBondingThea

7、dvantagesofadhesivebondinginclude:2•Bondingprovidesamoreuniformstressdistributionthanmechanicalfas-tenersbyeliminatingtheindividualstressconcentrationpeakscausedbymechanicalfasteners.AsshowninFig.8.1,thestressdistributionacrossthejointismuchmoreuniformforthead

8、hesivebondedjointthanforthemechanicaljoint,leadingtobetterfatiguelifethanthatformechanicallyfastenedjoint.Bondedjointsalsoprovidesuperiorvibrationanddampingcapability.•Duetotheelim