第五章 composites复合材料.docx

第五章 composites复合材料.docx

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第五章composites复合材料

5composites

教学目的:

Principleofcombinedactionofcomposites,ruleofmixtureofcomposites;longitudinalstrengthsfordiscontinuousandalignedfibrouscompositematerials

教学重点:

Principleofcombinedactionofcomposites,ruleofmixtureofcomposites

教学难点:

Longitudinalstrengthsfordiscontinuousandalignedfibrouscompositematerials

教学方法:

Multimedia

学时分配

5composites

（1）

5.1Introduction15min

5.2FiberReinforcedComposites

5.2.1Structuralcomposite10min

5.2.2ParticleandFiberReinforcedComposites20min

5composites

（2）

5.3Polymer-matrixcomposites

5.3.1Glassfiber-reinforcedpolymercomposites20min

5.3.2Carbonfiber-reinforcedpolymercomposites15min

5.3.3Aramidfiberreinforcedpolymercomposites10min

5.4Metal-matrixcomposites45min

5composites（3）

5.5Ceramic-matrixcomposites45min

5.6Carbon-matrixcomposites45min

教学过程与内容：

5.1Introduction

Acomposite,inthepresentcontext,isamultiphasematerialthatisartificiallymade,asopposedtoonethatoccursorformsnaturally.Inaddition,theconstituentphasesmustbechemicallydissimilarandseparatedbyadistinctinterface.Thus,mostmetallicalloysandmanyceramicsdonotfitthisdefinitionbecausetheirmultiplephasesareformedasaconsequenceofnaturalphenomena.Indesigningcompositematerials,scientistsandengineershaveingeniouslycombinedvariousmetals,ceramics,andpolymerstoproduceanewgenerationofextraordinarymaterials.Mostcompositeshavebeencreatedtoimprovecombinationsofmechanicalcharacteristicssuchasstiffness,toughness,andambientandhigh-temperaturestrength.Manycompositematerialsarecomposedofjusttwophases;oneistermedthematrix,whichiscontinuousandsurroundstheotherphase,oftencalledthedispersedphase.Thepropertiesofcompositesareafunctionofthepropertiesoftheconstituentphases,theirrelativeamounts,andthegeometryofthedispersedphase.‘‘Dispersedphasegeometry’’inthiscontextmeanstheshapeoftheparticlesandtheparticlesize,distribution,andorientation;thesecharacteristicsarerepresentedinFigure5.1.extraordinarymaterials.Mostcompositeshavebeencreatedtoimprovecombinationsofmechanicalcharacteristicssuchasstiffness,toughness,andambientandhigh-temperaturestrength.Manycompositematerialsarecomposedofjusttwophases;oneistermedthematrix,whichiscontinuousandsurroundstheotherphase,oftencalledthedispersedphase.Thepropertiesofcompositesareafunctionofthepropertiesoftheconstituentphases,theirrelativeamounts,andthegeometryofthedispersedphase.‘‘Dispersedphasegeometry’’inthiscontextmeanstheshapeoftheparticlesandtheparticlesize,distribution,andorientation;thesecharacteristicsarerepresentedinFigure15.1.

Figure5.1

OnesimpleschemefortheclassificationofcompositematerialsisshowninFigure5.2,whichconsistsofthreemaindivisions—particle-reinforced,fiber-rein-forced,andstructuralcomposites;also,atleasttwosubdivisionsexistforeach.Thedispersedphaseforparticle-reinforcedcompositesisequiaxed（i.e.,particledimensionsareapproximatelythesameinalldirections）;forfiber-reinforcedcomposites,thedispersedphasehasthegeometryofafiber（i.e.,alargelength-todiameterratio）.Structuralcompositesarecombinationsofcompositesandhomogenousmaterials.Thediscussionoftheremainderofthischapterwillbeorganizedaccordingtothisclassificationscheme.

Figure5.2

5.2ParticleAndFiberReinforcedComposites

5.2.1structuralcomposite

Astructuralcompositeisnormallycomposedofbothhomogeneousandcompositematerials,thepropertiesofwhichdependnotonlyonthepropertiesoftheconstituentmaterialsbutalsoonthegeometricaldesignofthevariousstructuralelements.Laminarcompositesandsandwichpanelsaretwoofthemostcommonstructuralcomposites;onlyarelativelysuperficialexaminationisofferedhereforthem.

1LAMINARCOMPOSITES

Alaminarcompositeiscomposedoftwo-dimensionalsheetsorpanelsthathaveapreferredhigh-strengthdirectionsuchasisfoundinwoodandcontinuousandalignedfiber-reinforcedplastics.Thelayersarestackedandsubsequentlycementedtogethersuchthattheorientationofthehigh-strengthdirectionvarieswitheachsuccessivelayer（Figure5.3）.Forexample,adjacentwoodsheetsinplywoodarealignedwiththegraindirectionatrightanglestoeachother.Laminationsmayalsobeconstructedusingfabricmaterialsuchascotton,paper,orwovenglassfibersembeddedinaplasticmatrix.Thusalaminarcompositehasrelativelyhighstrengthinanumberofdirectionsinthetwo-dimensionalplane;however,thestrengthinanygivendirectionis,ofcourse,lowerthanitwouldbeifallthefiberswereorientedinthatdirection.Oneexampleofarelativelycomplexlaminatedstructure