简介:quasistatic一致设计被做为不平表面的粘附描绘有效连贯的地区行为。在一致设计的上下文,为一个不平的接口的一致连贯的地区(HCZ)的拖拉对分离关系能在显微镜的粘附和decohesion进程期间由于不稳定性是高度摆动的。不稳定性被发现不仅个别地而且一起发生在粘合剂之中微粗糙的接触,导致广泛的精力驱散。基于HCZ关系的行为,为在不平表面的粘附描述导致不稳定性的精力驱散的一个框架被建议阐明明显的接口粘附上的粗糙的效果。二个非维的参数,与粗糙形态学有关的伪和与aw分发有关的n,被识别为控制精力驱散很关键。为浅粗糙和强壮的内在的粘合剂力量的一个接口,如果我们使它更不平,接口粘附能更强壮(减少伪)或降低它的aw密度(增加的n)。HCZ设计方法能潜在地被扩大并且采用了为与多尺度的浅粗糙设计表面从内在的粘附性质衔接明显的粘附。
简介:InordertoaccomplishreliablemechanicaldesignofMEMS,theinfluencesofsurfaceroughnessandoctadecyltrichlorosilane(OTS)self-assembledmonolayers(SAMs)onthemechanicalpropertiesofmicromachinedpolysiliconfilmsforMEMSareinvestigated.Surfaceeffectonthefracturepropertiesofmicromachinedpolysiliconfilmsisevaluatedwithanewmicrotensiletestingmethodusingamagnet-coilforceactuator.Statisticalanalysisofthesurfaceroughnesseffectsonthetensilestrengthpredicatedthesurfaceroughnesscharacterizationofpolysiliconfilmsbeingtestedandthedirectrelationofthemechanicalpropertieswiththesurfaceroughnessfeatures.Thefracturestrengthdecreaseswiththeincreaseofthesurfaceroughness.Theoctadecyltrichlorosilaneself-assembledmonolayerscoatingleadstoanincreaseoftheaveragefracturestrengthupto32.46%.SurfaceroughnessandthehydrophobicpropertiesofspecimenwhencoatedwithOTSfilmsarethetwomainfactorsinfluencingthetensilestrengthofmicromachinedpolysiliconfilmsforMEMS.
简介:这个工作检验包含平行表面的板击碎,轮流出现的长度使遭到了到热震动的机能上地分级的材料(FGM)的破裂行为。在长、短的裂缝的尖端的热压力紧张因素(TSIF)用一种单个不可分的方程技术被计算。引起快克开始的批评热吃惊螖Tc用一个压力紧张因素标准被计算。为一个Al2O3/Si3N4FGM盘子的TSIF和螖Tc的数字例子被举在TSIF和螖Tc上说明热性质阶段,裂缝间距和裂缝长度比率的效果。为给定的裂缝长度比率,在长、短的裂缝的尖端的TSIF能显著地被减少,螖Tc能被介绍适当材料阶段提高,这被发现。TSIF也在裂缝间距与减少戏剧性地减少。在短裂缝的尖端的TSIF可能为在某些裂缝几何学条件下面的长裂缝比那高。因此,短裂缝可以开始首先在装载的热吃惊下面成长而不是长裂缝。
简介:AnumericalanalysiswascarriedouttostudythemovingboundaryprobleminthephysicalprocessofpulsedNd-YAGlasersurfacemeltingpriortovaporization.Theenthalpymethodwasappliedtosolvethistwo-phaseaxisymmetricalmehingproblem.Computationalresultsoftemperaturefieldswereobtained,whichprovideusefulinformationtopracticallairtreatmentprocessing.Thevalidityofenthalpymethodinsolvingsuchproblemsispresented.
简介:Solutionstoapiezoelectrichalf-planewithafixedconductorsurfaceelectrodesubjectedtotwogeneralizedsingularities(linedislocationand/orlineforceandfreecharge)arepresented.Coulombforcesactingonthesingularitiesduetotheboundarypolarizationchargesofmediumandtheinductioncharg-esofconductorelectrodeareanalyzedindetail.Theinteractionbetweenthetwosingularitiesisalsoanalyzednumerically.ResultsshowthatCoulombforceswillbecomeimportantasthefreechargeapproachestheboundaryortwosingularitiesmoveclosely.
简介:Inthispaper,variousstrategiesofspiralirradiatingschemefortheflameformingofabowlshapedsurfaceareinvestigatedexperimentallyandnumerically.Experimentalworkisperformedusingaflametorchintegratedwitha2-axisCNCworkstation.TheABAQUSimplicitsolverisusedinthenumericalsimulation.Threedifferentstrategiesofthespiralirradiatingschemeareinvestigatedfortheflameformingofabowlshapedsurface.ThefirststrategyistheSimplespiralirradiatingscheme,thesecondistheRotationalspiralirradiatingscheme,andthethirdistheSymmetrical-Rotationalspiralirradiatingscheme.TheresultsshowthatusingtheSymmetricalRotationalspiralirradiatingscheme,abowlshapedsurfacewiththemaximumdeformationcanbeproduced,followedbyusingtheRotationalscheme,andtheSimplespiralscheme.ItisalsoconcludedfromtheresultsthatthespiralirradiatingschemewithSymmetrical-Rotational,RotationalandSimplespiralschemesleadtothemaximumsymmetriesintheproducedbowlshapedsurface,respectively.Allthenumericalresultsareingoodagreementwiththeexperimentalobservations.
简介:这份报纸探索生长在生物软材料的导致的词法不稳定性。鉴于生活纸巾的生长不仅改变它的几何学而且罐头改变它的机械性质,我们建议在材料的机械性质上合并生长的效果的一个精制容量的生长模型。在这个容量的生长模型和常规热压力模型之间的类比为小、有限的变丑问题被探讨,它基于建议模型为有限元素分析带大容易。导致的生长的例子出现起皱在软composites的行为,包括核心壳软柱体和三分层的软纸巾,被探索。结果和讨论在理解在软生物纸巾的形态发生和生长之间的关联预见模型的可能的应用(例如皮肤和肿瘤),以及在评估,变丑和软人工的材料的表面不稳定性行为由swelling/shrinkage导致了。
简介:ThenonlinearvibrationsofviscoelasticEuler–BernoullinanobeamsarestudiedusingthefractionalcalculusandtheGurtin–Murdochtheory.EmployingHamilton'sprinciple,thegoverningequationconsideringsurfaceeffectsisderived.Thefractionalintegro-partialdifferentialgoverningequationisfirstconvertedintoafractional–ordinarydifferentialequationinthetimedomainusingtheGalerkinscheme.Thereafter,thesetofnonlinearfractionaltime-dependentequationsexpressedinastate-spaceformissolvedusingthepredictor–correctormethod.Finally,theeffectsofinitialdisplacement,fractionalderivativeorder,viscoelasticitycoefficient,surfaceparametersandthickness-to-lengthratioonthenonlineartimeresponseofsimply-supportedandclamped-freesiliconviscoelasticnanobeamsareinvestigated.
简介:Aradialcrackemanatingfromasemi-circularnotchisofsignificantengineeringimportance.Accuratedeterminationofkeyfracturemechanicsparametersisessentialfordamagetolerancedesignandfatiguecrackgrowthlifepredictions.Thepurposeofthispaperistoprovideanefficientandaccurateclosed-formweightfunctionapproachtothecalculationofcracksurfacedisplacementsforaradialcrackemanatingfromasemi-circularnotchinasemi-infiniteplate.Resultsarepresentedfortwoloadconditions:remoteappliedstressanduniformstresssegmentappliedtocracksurfaces.Basedonacorrectionofstressintensityfactorratio,highlyaccurateanalyticalequationsofcracksurfacedisplacementsunderthetwoloadconditionsaredevelopedbyfittingthedataobtainedwiththeweightfunctionmethod.ItisdemonstratedthattheWuCarlssonclosed-formweightfunctionsareveryefficient,accurateandeasy-to-useforcalculatingcracksurfacedisplacementsforarbitraryloadconditions.Themethodwillfacilitatefatiguecrackclosureandotherfracturemechanicsanalyseswhereaccuratecracksurfacedisplacementsarerequired.