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1、JournalofMaterialsProcessingTechnology134(2003)135±144AnumericalandexperimentalstudyoffractureinRPstereolithographypatternsandceramicshellsforinvestmentcastinga,*bJ.C.Ferreira,A.MateusaDepartmentofMechanicalEngineering,InstitutoSuperiorTeÂcnico,Av.RoviscoPais,P-1049-001Lisbon,Portuga
2、lbDepartmentofMechanicalEngineering,InstitutoPoliteÂcnicodeLeiria,ESTG,AltodoVieiro,2400Leiria,PortugalReceived6February2001;receivedinrevisedform6February2001;accepted29October2002AbstractAnumericalandexperimentalstudyoffractureonepoxywebrapidprototyping(RP)stereolithography(SL)patt
3、ernsduringtheburnoutprocessofinvestmentcastingprocessispresented.Consideredaretheglasstransitiontemperatureoftheepoxyresin,thebucklingtemperatureoftheweblinkandthefracturetemperatureoftheceramicshell.Ourassumptionisthatceramicfracturedonotoccurathigherceramicshellrupturetemperaturean
4、dthatcrazefracturecouldoccurwhentheepoxyexpansioncausesbucklingofwebforatemperaturelowerthanthetemperatureofepoxyglasstransition.Thispremisesarevalidatedbyanacceptablecorrelationweobtainedbetweennumericalsimulationandexperimentalobservations.Itisfoundthattheweblinkbucklingandepoxyfra
5、cturearestronglyrelatedtothecross-sectionalzonesofthewebstructure.Theavoidanceofshellfracturebybucklingandcrazefractureoftheepoxy-webbedpatterninearlystagesoftheburnoutprocessisdiscussed.#2002ElsevierScienceB.V.Allrightsreserved.Keywords:Epoxyfracture;Ceramicfracture;Rapidprototyping
6、;Rapidtooling;Stereolithography1.Introductionthepattern.Lostpatternsareremovedbyburningitoutleavingahollowcavity.Thecavityisthen®lledwithmoltenLostwaxprocess,oneoftheoldestmetalmanufacturingmetaltocreatecastings.RPpatternsneedtohaveantechniquesthatdatesbackto4000±6000BC,isbeingusedex
7、cellentsurface®nishandmustpreciselyrecreate®newithoneofthemostmodernrapidprototyping(RP)tech-detailswithminimalburnoutresidue.nologiesthestereolithography(SL)process,formetalrepli-Ininvestmentcasting,themechanicalstrengthofinvest-cationofprototypeparts[1].Lostwaxprocess,actuallymentc
8、eramicshells
