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仿生工程学报:英文版
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  • 简介:Ceramicsaregoodalternativetometalasbearingcouplematerialsbecauseoftheirbetterwearresistance.AFiniteElement(FE)studywasperformedtoinvestigatethecontactmechanicsandstressdistributionofCeramic-on-Ceramic(COC)hipresurfacingprostheses.Itwasfocusedinparticularonaparametricstudytoexaminetheeffectsofradialclearance,loading,aluminacoatingontheimplants,bonequality,andfixationofcup-boneinterface.Itwasfoundthatareductionintheradialclearancehadthemostsignificanteffectonthepredictedcontactpressuredistributionamongalloftheparametersconsideredinthisstudy.Itwasdeterminedthattherewasasignificantinfluenceofnon-metallicmaterials,suchastheboneunderneaththebearingcomponents,onthepredictedcontactmechanics.Stressshieldingwithinthebonetissuewasfoundtobeamajorconcernwhenregardingtheuseofceramicasanalternativetometallicresurfacingprostheses.Therefore,usingaluminaimplantswithametalbackingwasfoundtobethebestdesignforceramicresurfacingprosthesesinthisstudy.Theloading,bonequality,andacetabularcupfixationconditionswerefoundtohaveonlyminoreffectsonthepredictedcontactpressuredistributionalongthebearingsurfaces.

  • 标签: contact MECHANICS HIP RESURFACING CERAMIC finite
  • 简介:Indryattachmentsystemsofspidersandgeckos,vanderWaalsforcesmediateattractionbetweensubstrateandanimaltarsus.Inparticular,thescopulaofEvarchaarcuataspidersallowsforreversibleattachmentandeasydetachmenttoabroadrangeofsurfaces.Hence,reproducingthescopula’sroughnesscompatibilitywhilemaintaininganti-bunchingfeaturesanddirtparticlerepellencebehaviorisacentraltaskforabiomimetictransfertoanengineeredmodel.InthepresentworkwemodelthescopulaofE.arcuatafromamechano-elasticpointofviewanalyzingtheinfluenceofitshierarchicalstructureontheattachmentbehavior.Byconsideringbiologicaldataofthegeckoandspider,andthesimulationresults,theadhesivecapabilitiesofthetwoanimalsarecomparedandimportantconfirmationsandnewdirectivesinordertoreproducetheoverallstructurearefound.Moreover,apossiblesuggestionofhowthespiderdetachesinaneasyandfastmannerisproposedandsupportedbytheresults.

  • 标签: BIONICS SPIDER DRY ADHESION mechano-elastic model
  • 简介:Wedescribeafewmathematicaltoolswhichallowtoinvestigatewhetherair-waterinterfacesexist(underprescribedconditions)andaremechanicallystableandtemporallypersistent.Intermsofphysics,air-waterinterfacesaregovernedbytheYoung-Laplaceequation.Mathematicallytheyaresurfacesofconstantmeancurvaturewhichrepresentsolutionsofanonlinearellipticpartialdifferentialequation.Althoughexplicitsolutionsofthisequationcanbeobtainedonlyinveryspecialcases,itis-undermoderatelyspecialcircumstances-possibletoestablishtheexistenceofasolutionwithoutactuallysolvingthedifferentialequation.Wealsoderivecriteriaformechanicalstabilityandtemporalpersistenceofanairlayer.Furthermorewecalculatethelifetimeofanon-persistentairlayer.Finally,weapplythesetoolstotwoexampleswhichexhibitthesymmetriesof2Dlattices.TheseexamplescanbeviewedasabstractionsofthebiologicalmodelrepresentedbytheaquaticfernSalvinia.

  • 标签: interfaces air LAYERS differential geometry stability
  • 简介:QuestionsconcerningthefunctionalroleofthehollowregionofthebutterflyPyrameisatalanta(L.)scaleareexperimentallyinvestigated.Attentionwasinitiallydirectedtothisproblembyobservationofthecomplexmicrostructureofthebutterflyscaleaswellasotherstudiesindicatinghigherliftonbutterflywingscoveredwithscale.Theaerodynamicforcesweremeasuredfortwooscillatingscalemodels.ResultsindicatedthattheaircavityofanoscillatingmodelofthePyrameisatalanta(L.)scaleincreasedtheliftbyafactorof1.15andreducedthedampingcoefficientsbyafactorof1.38.Themodificationoftheaerodynamiceffectsonthemodelofbutterflyscalewasduetoanincreaseofthevirtualairmass,whichinfluencedthebody.Thehollowregionofthescaleincreasedthevirtualairmassbyafactorof1.2.Thevirtualmassofthebutterflyscalewiththehollowregionwasrepresentedasthesumofairmassoftwoimaginarygeometricalfigures:acircularcylinderaroundthescaleandaright-angledparallelepipedwithinthehollowregion.TheinteractionmechanismofthebutterflyPyrameisatalanta(L.)scalewithaflowwasdescribed.Thisnovelinteractionmechanismexplainedmostgeometricalfeaturesoftheairpermeablebutterflyscale(invertedV-profileoftheridges,nozzleofthetipedge,hollowregion,andopeningsoftheupperlamina)andtheirarrangement.

  • 标签: 仿生学 蝶形 虚质量 生物研究
  • 简介:ThekinematicsofturningmaneuversofstartledCrucianCarp(Carassiusauratus)arepresented.AllescaperesponsesobservedareC-typefast-starts.Thepositionofthecenterofmassandthemomentofinertiaofthefisharecalculated.Theresultsshowthatthepositionofthecenterofmassisalwaysat35%ofthelengthofthefishfromtheheadandthepositionofthecenterofmassandmomentofinertiacanbeconsideredunchangedduringC-startofCrucianCarp.HydrodynamicanalysisoftheC-startisgivenbasedonthekinematicsdatafromourexperiments.TheC-startconsistsofthreestages.Instage1,thetailfinoffishrapidlyflapsinonedirection,andalargemomentactsonthefish'sbody,whichrotatesaroundthecenterofmasswithanangularacceleration.Instage2,thetailfinflapsmoreslowlyintheoppositedirectionatslowerspeed,thefish'sbodyrotatesaroundthecenterofmasswithangulardecelerationandthecenterofmassofthefishmovesalonganarc.Instage3,themomentapproximatelyequalszero,thefish'sbodystopsrotatingandthecenterofmassthemovesalongastraightline.

  • 标签: 欧洲鲫鱼 回转动力学 力矩 质量中心 惯性矩
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  • 简介:Anewbionicapproachispresentedtofindtheoptimaltopologiesofastructurewithtension-onlyorcompression-onlymaterialbasedonboneremodellingtheory.Bytraditionalmethods,thecomputationalcostoftopologyoptimizationofthestructureishighduetomaterialnonlinearity.Toimprovetheefficiencyofoptimization,thereference-intervalwithmaterial-replacementmethodispresented.Inthemethod,firstly,theoptimizationprocessofastructureisconsideredasboneremodellingprocessunderthesameloadingconditions.AreferenceintervalofStrainEnergyDensity(SED),correspondingtothedeadzoneorlazyzoneinbonemechanics,isadoptedtocontroltheupdateofthedesignvariables.Secondly,amaterial-replacementschemeisusedtosimplifytheFiniteElementAnalysis(FEA)ofstructureinoptimization.Intheoperationofmaterial-replacement,theoriginaltension-onlyorcompression-onlymaterialindesigndomainisreplacedwithanewisotropicmaterialandtheEffectiveStrainEnergyDensity(ESED)ofeachelementcanbeobtained.Finally,theupdateofdesignvariablesisdeterminedbycomparingthelocalESEDandthecurrentreferenceintervalofSED,e.g.,theincrementofarelativedensityisnonzeroifthelocalESEDisoutofthecurrentreferenceinterval.Numericalresultsvalidatethemethod.

  • 标签: NATURE inspired TOPOLOGY OPTIMIZATION tension/compression-only MATERIAL
  • 简介:Inthispaperanewreactivemechanismbasedonperception-actionbionicsformulti-sensoryintegrationappliedtoUn-mannedAerialVehicles(UAVs)navigationisproposed.Thestrategyisinspiredbytheolfactorybulbneuralactivityobservedinrabbitssubjecttoexternalstimuli.ThenewUAVnavigationtechniqueexploitstheuseofamultiscrollchaoticsystemwhichisabletobecontrolledinreal-timetowardslesscomplexorbits,likeperiodicorbitsorequilibriumpoints,consideredasperceptiveorbits.Thesearesubjecttoreal-timemodificationsonthebasisofenvironmentchangesacquiredthroughaSyntheticApertureRadar(SAR)sensorysystem.Themathematicaldetailsoftheapproacharegivenincludingsimulationresultsinavirtualen-vironment.TheresultsdemonstratethecapabilityofautonomousnavigationforUAVbasedonchaoticbionicstheoryincom-plexspatialenvironments.

  • 标签: chaotlc system perception-action bionlcs UAV multi-sensoty INTEGRATION
  • 简介:Aroboticfishdrivenbyoscillatingfins,"CownoseRay-I",isdeveloped,whichisindorsoventrallyflattenedshapewithoutatail.Theroboticfishiscomposedofabodyandtwolateralfins.Athree-factorkinematicmodelisestablishedandusedinthedesignofamechanism.Bycontrollingthethreekinematicparameters,theroboticfishcanaccelerateandmaneuver.Forwardvelocityisdependentonthelargestamplitudeandthenumberofwavesinthefins,whiletherelativecontributionoffinbeatfrequencytotheforwardvelocityoftheroboticfishisdifferentfromtheusualresult.Ontheotherhand,experimentalresultsonmaneuveringshowthatphasedifferencehasastrongereffectonswervingthanthelargestamplitudetosomeextent.Inaddition,aspropulsionwavespassfromthetrailingedgetotheleadingedge,theroboticfishattainsabackwardvelocityof0.15m·s-1.

  • 标签: ROBOTIC fish pectoral OSCILLATION PROPULSION LARGEST
  • 简介:Robotlocomotionisanactiveresearcharea.Inthispaperwefocusonthelocomotionofquadrupedrobots.Aneffectivewalkinggaitofquadrupedrobotsismainlyconcernedwithtwokeyaspects,namelyspeedandstability.Thelargesearchspaceofpotentialparametersettingsforlegjointsmeansthathandtuningisnotfeasibleingeneral.Asaresultwalkingparametersaretypicallydeterminedusingmachinelearningtechniques.Amajorshortcomingofusingmachinelearningtechniquesisthesignificantwearandtearofrobotssincemanyparametercombinationsneedtobeevaluatedbeforeanoptimalsolutionisfound.Thispaperproposesadirectwalkinggaitlearningapproach,whichisspecificallydesignedtoreducewearandtearofrobotmotors,jointsandotherhardware.Inessenceweprovideaneffectivelearningmechanismthatleadstoasolutioninafasterconvergencetimethanpreviousalgorithms.Theresultsdemonstratethatthenewlearningalgorithmobtainsafasterconver-gencetothebestsolutionsinashortrun.Thisapproachissignificantinobtainingfasterwalkinggaitswhichwillbeusefulforawiderangeofapplicationswherespeedandstabilityareimportant.Futureworkwillextendourmethodssothatthefasterconvergencealgorithmcanbeappliedtoatwoleggedhumanoidandleadtolesswearandtearwhilststilldevelopingafastandstablegait.

  • 标签: 有腿机器人 运动方式 步态 操作系统
  • 简介:Inthispaperweinvestigatedhowtherunningspeedwouldaffectthedynamicsofbodypitching,andwhetherbodyinertiaisimportantforanimals.Passivetrottingofspring-massmodelandpassiveboundingofspring-beammodelwerestudiedatdifferentspeedsfordifferentsetsofbodyparametersrespectively.Furthermore,differentbodyinertiaswereusedinbounding.Wefoundthatrunningspeedexertseffectonlegperformancebymeansofcentrifugalforce.Thecentrifugalforcecanbeunderstoodasanenhancementtothenaturalfrequencyofthespring-masssystem.Thedisadvantageofbodypitchingmaybeoffsetbythegreatincreaseincentrifugalforceathighspeed.Theresultsalsorevealthatbodymassdistributionmightnotbethemainreasonforthedifferenceinmaximalrunningspeedsofdifferentanimals.

  • 标签: BODY PITCHING LEG performance running speed
  • 简介:Thepaperpresentsadetailedanalysisofexperimentaldatainordertocharacterizetheelasticpropertiesofarteries.Suchanalysiswouldprovideagoodbasisforevaluationofbiomimeticvasculargrafts.Sincethelatterneedstoexhibitsimilarpropertiesofnativetissue,itisimportanttoaccuratelycharacterizethebiomimeticsampleinalargerangeofappliedstresses.Thestress-strainpropertiesvaryaccordingtothespecificpathology(e.g.arteriosclerosis,aneurism)andthetissuegraftmustbechosencorrectly.Twomodelsareproposedinthispaperonthestress-straincharacteristics.Anextensionforfrequency-domainanalysisisprovidedforoneofthemodels.Thecomparisonbetweenvasculargraftsandnativetissueforcarotidandthoracicarteriesinpigsareingoodagreementwithresultsfromliterature.Theproposedexperimentalmethodofferssuitableparametersforidentifyingmodelswhichcharacterizebothelasticityandstiffnesspropertiesoftheanalyzedtissues(stress-strain).Theproposedmodelsshowgoodperformanceincharacterizingtheintrinsicmaterialproperties.

  • 标签: BIOMIMETIC BIOMATERIALS vascular GRAFT NATIVE and