仿生学英文文献

MaterialsScienceandEngineeringA483–484(2008)625–628BasicstudyofbiomimeticcompositematerialsintheforewingsofbeetlesJinxiangChena,b,∗,GuangzeDaib,YinglianXua,MasaharuIwamotoc,baSchoolofMaterialsScience,ZhejiangInstituteofScienceandTechnology,Hangzhou,Zhejiang310033,ChinabSchoolofMaterialsScienceandEngineering,SouthwestJiaotongUniversity,Chengdu,Sichuan610031,ChinacDivisionofAdvancedFibro-Science,KyotoInstituteofTechnology,Matsugasaki,Sakyo-ku,Kyoto606-8585,JapanReceived6June2006;receivedinrevisedform25September2006;accepted28September2006AbstractInspiredbybio-structuresinoptimalmaterialsdesign,themicrostructuresandbio-structuredesigntechniquesintheforewingoftheAllomyrinadichotomabeetlewereexaminedinordertoimproveuponengineeringdesigns.Fromthisstudy,thefollowingresultswereobtained:Thefibervolumefractionandtheshapeofthefibercross-sectionintheforewingdependontheforewing’sposition,whiletheshapeofthecross-sectionissquareorcircularwhenfibercontentishighorlow,respectively.Withinthelaminatedlayersoftheforewing’schitinfibers,fiberscross-linktoformareticularstructure,thusprovidingtwo-dimensionalstrengthandcleverlyavoidingthecommonweaknessfoundinwovenfibersduetothephysicalstraincausedbyfiberoverlapandbend.Betweenthelaminatedlayers,thebeetle’sforewingisthree-dimensionallyreinforcedbytrabecularstructures.Inthisstudy,bothbiomimeticscompositematerialsandtheirdesigntechniquesarediscussed.©2007PublishedbyElsevierB.V.Keywords:Anisotropy;Optimumdesign;Laminatedstructure;Biomimetics;Beetle1.IntroductionTodevelopasuitablemethodforthestructuraldesignofcompositematerials,anewdesigntechniqueisrequiredinordertodiscovercompositematerialsthathavethemostsuit-ablefibersorientedatareaswheretheyaremostneeded,alongwiththeexactquantitiesrequired[1].Throughouthistory,manyorganismshaveevolvedinordertoadapttotheirnaturalenvi-ronment.Theseevolutionaryexamplesmayprovideevidenceastohownaturehashelpedtheseorganismsovercometheinterfa-cialweaknessespresentincertainorganismstructures,aswellasallowtheuseofbiomimeticstoimprovereinforcementmech-anismsin3Dcomposites.Forthisreason,thestructuresofthebeetleforewinganditsmechanicalbehaviorwereinvestigatedinordertodevelopbiomimeticscompositematerialsincurrentresearch[2–4].Withintheforewingstructuresofinsects,investigatorshavefoundlaminatedstructureswheretheforewingproteinactsastherelativelysoftmatrixwhilethechitinfiberactsastherein-∗Correspondingauthorat:SchoolofMaterialsScience,ZhejiangInstituteofScienceandTechnology,Hangzhou,Zhejiang310033,China.E-mailaddresses:[e-mail],[e-mail](J.Chen).forcingfiber[5–7].Boththelaminatedformatofthechitinfibers[5–8]andthemechanicalcharacteristicsoftheseequian-gularlaminatinglayersofthebiomimeticscomposites[9,10]havebeenpreviouslyreported.Theauthorshavealsodevotedmuchefforttothebiomimeticsofthebeetle’sforewingincludingitsmacro-structures[2],thenon-equiangularlaminatingstruc-ture[3]andthethree-dimensionalreinforcedstructures[4].Inthepresentwork,boththe“shape”designtechniqueoffiber’scross-sectionandthetypicalreticularcross-linkingoftwo-dimensionalreinforcedstructureswithinbeetleforewingsarediscussed.2.Experimentalspecimensandmethod2.1.SpecimensAspecimenofamaleAllomyrinadichotoma,asshowninFig.1,wasusedasatestsample.Sincelivesamplesareused,theymustbetreatedusingprofes-sionalmethodsinordertoensurethattheirstructuralintegrityremainsunchangedduringsamplepreparation.Inthemethodusedhere,livesamplesareleftatroomtemperaturefor1dayor,insomecases,uptoseveralmonths.Previousexperimentalresultsshowthatwhilethismethodmayresultindryingduetolossofwaterandpartialdamageofthecellmembrane,the0921-5093/$–seefrontmatter©2007PublishedbyElsevierB.V.doi:10.1016/j.msea.2006.09.180626J.Chenetal./MaterialsScienceandEngineeringA483–484(2008)625–628Fig.1.AnadultbeetleofAllomyrinadichotoma.originalstructuralintegrityoftheforewingdoesremainintact[2].Inthisexperiment,unlessotherwisenoted,thismethodwasusedforsamplepreparation.2.2.ScanningelectronmicroscopyInordertoinvestigatethemicrostructureofthelaminatedcross-section,theupperforewingofA.dichotomawascutoffalongsurfacesbothnormalandslantedtotheX–Yplane.Somesamplesoftheelytraweredeproteinatedbyboilingthemin10%KOHfor3hat100◦C[6,8].Thespecimenswerethenobservedbyscanningelectronmicroscopy(Hitachi,SEMS-510at15kVandNikon,ESEM-2700at20kV,420Paor460Pa).3.Experimentalresultsanddiscussion3.1.Optimizationofthecross-sectionalshapeandvolumedensityofthechitinfibersTheoptimizationofthecross-sectionalshapeandvolumedensityofthechitinfibersresultsinanincreasedforewingstrengthassociatedwithadecreaseinweight.Inordertodiscussthe“shape”(cross-section)and“amount”(volumefraction)ofreinforcedfiberenhancementsincurrentbio-compositematerials,themorphologicalimagesofchitinfiberlocatedatboththeexternalpositionoftheoutsideedgeandaroundthemiddlelamination(seeFig.5)oftheforewingareshowninFig.2.Thefibersattheexternalpositionoftheoutsideedgeintheforewinghaveacircularcross-sectionwithasparsedistributionasinFig.2(a)and(b),andthosearoundthemiddlelaminationarerectangularwithadensedis