fracture of natural biomaterials：天然生物材料的断裂

《fracture of natural biomaterials：天然生物材料的断裂》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。

1、FractureofnaturalbiomaterialsTACharlieFlorekInbasementoffiberopticsbuildingDepartmentofBiomedicalEngineeringRutgers,TheStateUniversityofNewJerseySafety:1.Safetyglassesmustbewornduringtheimpactfracturetests.2.Usegloveswhenworkingwiththeimpactapparatus.3.Standwellclearoftheimpactapparatusduringoperati

2、on4.NEVERstandinfrontorbehindthemachineduringtesting(thefrontisthedirectioninwhichthependulumswings).[1]PurposeTherearetwogoalstothislab:1.tounderstandhowmaterialsfractureandhowthisisrelatedtotheirmicrostructure.2.torelatetheconceptsofmaterialsfracturetothepropertiesandstructureofnaturalbiomaterials

3、.Youwillexaminethesurfacesofmaterialswhichhaveundergonebrittleandductilefracturetoseethetypicalmorphologicalfeaturesofthefracturesurface.Youwillperformimpactfracturetestsonaceramic,wood(acrossthegrainandwiththegrain)andbone.Aftercompletingtheexperimentsyoushouldbeableto:·Explainhownaturalbiomaterial

4、shaveevolvedtoreducetheriskoffracture.·Explainwhypureceramicsarepoorsyntheticbiomaterials.·Estimatethefracturesurfaceenergyforabrittlematerial.[2]IntroductionNaturalbiomaterialssuchasbone,teethandwoodhaveevolvedtohaveacomplexmicrostructurewhichenablesthemtowithstandlargemechanicalstressesandimpactsw

5、ithoutfracturing.Theyarealsorelativelylightandhaveahighstrengthtomassratio.Syntheticbiomaterialsbasedonpurepolymers,ceramicsormetalscannotmatchthenaturalmaterialstheyreplaceintermsofstrength,fractureresistanceandmass.However,compositeartificialbiomaterialswhichcontainmorethanonematerialandhaveacaref

6、ullyengineeredmicrostructurecanhavesimilarpropertiestothenaturalbiomaterialstheyreplace.Thislabwilluseaseriesofimpactfractureteststoexaminetherelativefractureresistanceofnaturalandsyntheticmaterials.ThetestislooselybasedonthestandardCharpyimpacttestforexaminingbrittleandductilefractureinbulksamples.

7、[3]ApparatusTheapparatusisapurposebuiltimpacttesterbaseduponaswingingpendulum(seeFig.1).Thependulumimpactsthetestsampleatthebottomofitsdownwardswing.Theimpactbreaksthesampleandthependulumcontinuesonit