简介：Weconsideramathematicalmodelwhichdescribesacontactbetweenadeformablebodyandafoundation.ThecontactisbilateralandmodelledwithTresca’sfrictionlaw.Thegoalofthispaperistostudyanoptimalcontrolproblemwhichconsistsofleadingthestresstensorascloseaspossibletoagiventarget,byactingwithacontrolontheboundaryofthebody.Westateanoptimalcontrolproblemwhichadmitsatleastonesolution.Wealsointroducetheregularizedcontrolproblemforwhichwestudytheconvergencewhentheregularizationparametertendstozero.Finally,anoptimallyconditionisestablishedforthisproblem.

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简介：Basedonelementarygrouptheory,theblockpivotmethodsforsolv-ingtwo-dimensionalelasticfrictionalcontactproblemsarepresentedinthispaper.Itisprovedthatthealgorithmsconvergewithinafinitenumberofstepswhenthefrictioncoefficientis'relativesmall'.Unlikemostmathematicalprogrammingmeth-odsforcontactproblems,theblockpivotmethodspermitmultipleexchangesofbasicandnonbasicvariables.

简介：这份报纸瞄准到份量上估计kineticfrictional模型的申请特别地，处于稠密的状况模仿干燥小粒的材料的运动在Couette配置的环形的砍。摩擦应力的重量被改变在稠密的小粒的流动学习摩擦压力的贡献。结果证明纯kinetic-theory-based计算液体动力学(CFD)模型(没有摩擦应力)在预言上当增加摩擦应力时，主导的固体稠密的小粒的流动打手势[Schaeffer，D.G。(1987)。在描述不可压缩的小粒的流动的进化方程的不稳定性。微分方程的杂志，66(1)，1950]与固体压力[Lun，C.K.K.，野人，S.B.，杰弗里，D.J.，与Chepurniy，N。(1984)。为小粒的流动的运动理论：在Couette流动的无弹性的粒子和一块一般流动地里的稍微无弹性的粒子。液体力学的杂志，140，223256]在CFD，模型改进模拟更好遵守可得到的试验性的结果。结果也建议摩擦压力传播在稠密的小粒的流动起一个重要作用并且不应该在小粒的流动模拟被忽视。到试验性的数据的兼容模拟结果被增加摩擦应力的重量到1.251.5的一个因素看见。这些改进模拟结果建议当前的组成的关系(kineticfrictional模型)需要被改善以便更好反映真实稠密的小粒的流动。

简介：Anewalgorithmforsolvingthethree-dimensionalelasticcontactproblemwithfrictionispresented.Thealgorithmisanon-interiorsmoothingalgorithmbasedonanNCPfunction.Theparametricvariationalprincipleandparametricquadraticprogrammingmethodwereappliedtotheanalysisofthree-dimensionalfrictionalcontactproblem.Thesolutionofthecontactproblemwasfinallyreducedtoalinearcomplementarityproblem,whichwasreformulatedasasystemofnonsmoothequationsviaanNCP-function.Asmoothingapproximationtothenonsmoothequationswasgivenbytheaggregatefunction.ANewtonmethodwasusedtosolvetheresultingsmoothingnonlinearequations.Thealgorithmpresentediseasytounderstandandimplement.ThereliabilityandefficiencyofthisalgorithmaredemonstratedbothbythenumericalexperimentsofLCPinmathematicalwayandtheexamplesofcontactproblemsinmechanics.

简介：Thestudyoffrictionalpropertiesofhumanskinisimportantformedicalresearch,skincareproductsandtextileexploi-tation.Inordertoinvestigatetheinfluenceofnormalloadandslidingspeedonthefrictionalpropertiesofskinanditspossiblemechanism,testswerecarriedoutonamulti-specimenfrictiontester.Whenthenormalloadincreasesfrom0.1Nto0.9N,normaldisplacementandthefrictioncoefficientofskinincrease.Thefrictioncoefficientisdependentontheload,indicatingthatbothadhesionanddeformationcontributetothefrictionbehaviour.Thedeformationfrictionwasinterpretedusingtheploughmodeloffriction.Whenslidingspeedincreasesfrom0.5mm·s?1to4mm·s?1,thefrictioncoefficientincreasesand'stick-slip'phenomenaincrease,indicatingthathystereticfrictioncontributestothefriction.Thehystereticfrictionwasin-terpretedusingschematicofenergytranslationduringtherigidsphericalprobeslidingonthesoftskinsurface,whichprovidesanexplanationfortheinfluenceoftheslidingspeedonthefrictionalcharacteristicsoftheskin.

简介：Amathematicalprogramisproposedforthehighlynonlinearprobleminvolvingfrictionalcontact.Aprogram-patternusingthefastmultipoleboundaryelementmethod(FMBEM)isgivenfor3-DelasticcontactwithfrictiontoreplacetheMonteCarlomethod.Anewoptimizedgeneralizedminimalresidual(GMRES)algorithmispresented.Numericalexamplesdemonstratethevalidityoftheprogram-patternoptimizationmodelfornode-to-surfacecontactwithfriction.TheGMRESalgorithmgreatlyimprovesthecomputationalefficiency.

简介：以便减少磨擦力量并且在低速度消除一个技工系统的粘住滑倒现象，一个方法基于超声的微开车技术被建议改变摩擦特征。顺时针方向激动并且在超声的致动器的二个纵的夹钳门栓的震荡器上驾驶点的逆时针方向的显微镜的椭圆的运动将产生超声的润滑油行动；而且，磨擦能被调整震荡器的颤动的振幅活跃地控制。为磨擦控制的试验性的安装用航空的指南，力量传感器和一低速度时刻被设计motor.Fuzzy控制理论被使用进这个系统。实验显示磨擦力量大部分被减少了，试验性的系统的运动是稳定的。当超声的致动器和负担is3.8kg和马达的全部的团正在开车时，磨擦系数仅仅是大约0.0053速度是0.5mm/s。

简介：Transmissionofelasticwavesthroughamicrogapbetweentwosolidswithconsiderationoffrictionalcontactisinvestigated.ByusingtheFourieranalysistechniqueandthecorrectivesolutionmethod,thenonlinearboundaryproblemisreducedtoasetofalgebraicequations.Numericalresultsexhibitthelocationsandextentsofseparation,slip,andstickzones,theinterfacetractions,andtheenergypartition.Theeffectsofgapwidth,frictionalcoefficients,andtheincidentangleonthewavetransmissionarediscussedindetail.Theresultsshowthathigherharmonicsaregeneratedduetothelocalcontact/slipattheinterface.

简介：Theexperimentalstudyofthechangeofwavevelocityinfaultregionsbeforeinstabilityoffrictionalslidingofrockswasconducted.Experimentsshowthatbeforetheinstabilityoffrictionalslidingofrocks,thechangeofwavevelocitycannotbeobservedalonglinesononesideofthefault,buttheprecursorofthedecreaseofwavevelocitycanbeobservedalonglinesacrossthefault.Therefore,whenwetrytopredicttheearthquakesofthestick-sliptypeinfaultregionsbyusingtheanomalyofwavevelocity,themeasuringlinesacrossthefaultsshouldbeselected.

简介：Toexploretheapplicationofsevereplasticdeformationforgrainrefinementinsteelproduction,anewmethodcalledcontinuousfrictionalangularextrusion(CFAE)wasappliedtorefinethegrainofinterstitial-freesteel.Thedeformationwascarriedoutatroomtemperatureandindividualsheetspecimenswereprocessedindifferentnumberofpasses.Anoverallgrainsizeof200nmwasachievedafter8passesandtheproportionofhigh-angleboundariestothetotalboundarieswasmorethan60%.ThroughthecharacterizationofhighresolutionEBSD,X-raydiffraction(XRD)andhardnesstesting,thispaperdiscussedtheevolutionofmicrostructuresandtexturesduringdeformationandexploredthedevelopmentdirectionofthemethod.

简介：数字模拟基于计算液体动力学(CFD)是为在FSW期间调查内在的热机械的条件的份量上的一条有用途径，例如温度地和材料变丑地。在FSW的CFD模拟的关键问题之一是摩擦边界条件的使用，它在数字模型代表在焊接工具和细工品之间的磨擦。在这研究，三维的数字模拟被进行在AA2024的FSW期间分析热转移和塑料变丑行为。为比较目的，边界速度(BV)模型和边界砍压力(BSS)模特儿被雇用以便在在FSW预言温度和材料变丑估计他们的表演。注意不同边界条件在材料变丑上在温度，而是相当不同的预言上产出类似的预言有趣。数字预言与试验性的结果相比。当由BV模型和试验性的大小的预言之间有大差别时，由BSS模型的预言的变丑地区几何学与试验性的结果一致。BSS模型在变丑地区几何学上产出更合理的预言的事实被归因于它的能力自动地在工具/细工品接口调整接触状态。在温度地和材料变丑地上基于有利预言，BSS模型被建议比BV模型在FSW的数字模拟有更好的表演。

简介：Thispaperhadinvestigatedtheeffectsofsurfacewettabilityonthefrictionalresistanceofturbulenthorizontalflowfortapwaterinfivepipesmadeofvariousmaterialsandfourkindsofliquidsinapolytetrafluoroethylene(PTFE)pipe,withthesameinnerdiameterof14mm.Pressuredropsweremeasuredunderdifferentflowratesthroughanexperimentalflowloop.Thecontactanglesandadhesionworkofliquidsincontactwithpipesurfacesweredeterminedusingacontactanglemeter.Basedonthedimensionandregressionanalyses,twokindsofmodifiedrelationshipsbetweenthefrictionalcoefficientandthesurfacewettabilitywereestablishedaccordingtothemeasuredresultscorrespondingtotapwaterinfivepipesandfourliquidsinPTFEpipe.Theexperimentalresultsshowthatthesurfacewettabilityhassomeinfluenceonfrictionalcoefficientofthestudiedliquidsflowinginmacroscalepipes,andthefrictionalcoefficientdecreaseswiththeincreaseofthecontactangleatthesameReynoldsnumber.Meanwhiletheeffectofwettabilityonthehydrophobicsurfaceisgreaterthanthatonthehydrophilicone.Thefrictionalcoefficientspredictedbythemodifiedformulashaveverifiedtobeingoodagreementwiththeexperimentalvalues,therelativeerrorsofwhicharewithin±6%and±3%forthetapwaterflowinginfivedifferentpipesandfourkindsofliquidsflowinginPTFEpipe,respectively.

简介：High-velocityfrictionexperimentswereconductedonclayeyfaultgougecollectedfromHongkououtcropofBeichuanfault,locatedatthesouthwesternpartofLongmenshanfaultsystemthatcausedthedisastrous2008Wenchuanearthquake.Theultimatepurposeofthisstudyistoreproducethisearthquakebymodelingbasedonmeasuredfrictionalproperties.Drygougeofabout1mminthicknesswasdeformeddryatslipratesof0.01to1.3m/sandatnormalstressesof0.61to3.04MPa,usingarotary-shearhigh-velocityfrictionaltestingmachine.Thegougedisplaysslipweakeningbehaviorasinitialpeakfrictiondecaystowardssteady-statevaluesafteragivendisplacement.Bothpeakfrictionandsteady-statefrictionremainhighatslowslipratesareexaminedandgougeonlyexhibitsdramaticweakeningathighsliprates,withsteady-statefrictioncoefficientvaluesofabout0.1to0.2.Specificfractureenergyrangesfrom1to4MN/minourresultsandthisisofthesameorderasseismicallydeterminedvalues.LowfrictioncoefficientsmeasuredonexperimentalfaultsareinbroadagreementwithlackofthermalanomalyobservedfromtemperaturemeasurementsinWFSD-1drillhole(WenchuanEarthquakeFaultScientificDrillingProject),whichcanbeexplainedbyevensmallerfrictioncoefficientfortheWenchuanearthquakefault.High-velocityfrictionexperimentswithporewaterneedstobedonetoseeifevensmallerfrictionisattainedornot.Shinyslickensidesurfacesformathighsliprates,butnotatslowsliprates.Slipzonewithslickensidesurfacechangesitscolortodarkbrownandformsduplex-likemicrostructures,whicharesimilartothosemicrostructuresfoundinthefaultgougesfromtheHongkououtcrop.DetailedcomparisonsbetweenexperimentallydeformedgougesamplesandWFSDdrillcoresinthefuturewillrevealhowmuchwecouldreproducethedynamicweakeningprocessesinoperationinfaultzonesduringWenchuanearthquakeatpresent.