简介:OnApril23rd,ChinaDatangCorporationandEdFofFranceheldasigningceremonyforajoint-venturecontractofDatangSanmenxiaPowerGenerationCompanyLtd.inHenanProvince.ThisisthefirstcooperationprojectbetweenDatangandEdF.TheDatangSanmenxiaPowerGenerationCompany
简介:Inthiscontribution,insideturningofathin-walledcylinderisinvestigatedinsimulation.Self-excitedvibrationscanariseduetorepeatedcuttingofthesamesurface,thatleadtoinstability.Aflexiblemultibodysystemmodelofthesystemisthebasisforasubsequentanalysisofthestabilityoftheprocess.Stabilityanalysisisdoneusinganapproximationasatime-discretesystemviathesemi-discretizationmethod.Anadaptronicturningchiselcomprisingapiezoactuatorandsensorsisthenusedincombinationwithdifferentcontrolconceptstoimprovethestabilityoftheprocess.Theeffectivenessofthedifferentstrategiesiscomparedbasedontheinfluenceonthestabilitycharts.AclassicH∞controllerbasedonamodelofthecoupledsystemofworkpieceandtoolcanonlyyieldsomeimprovements,whenanadditionalmeasurementoftheworkpiecedisplacementisadded.IncorporatingknowledgeonthecuttingprocesscouplingworkpieceandtoolusingagainscheduledH∞controllerallowsfurtherimprovements.However,robustnesswithrespecttomodeluncertainties,notablyconcerningtheforcelaw,remainsanissue.
简介:本文指出[1]中关于Ap权反向Hoelder不等式的证明有误并给出一个正确的证明.
简介:Thispaperinvestigatestheequivalentmodelforthefrictionboundaryconditionbetweenblankandholderduringsheetmetalformingsimulation,andproposesanequivalentalgorithm,thethicknessthresholdvaluealgorithm,forthefirsttimebasedonthicknessweighting.Thisalgorithmassumesthattheholderclearanceisuniformduringsheetmetalforming;andthemainreasonfortheunevennessoffrictionforcedistributionundertheholderisthattheunevendeformationoftheblankleadstoitsuneventhicknessdistribution,whichmakesthelocalpressureontheblankdistributedunevenly.Thealgorithmproposedinthispapercaneffectivelysimulatetheinfluenceoftheunevennessontheformingprocess.Validityofthisalgorithmisverifiedbyacomparisonbetweenthesimulationresultsandtheexperimentalonesforthedrawingprocessofacarspringbase.
简介:Atfirst,aseriesoffiniteelementmethod(FEM)simulationtestswereusedtofindthecriticalformingconditionsofhot-galvanizedsheetsteelduringtherectangularboxdrawingprocessingwhenconstantblankholderforceswereapplied.Accordingthetestresults,thereasonablealterationscopeofinitialvariableblankholderforce(VBHF)wasas1.9~2.3T.Then,basedonthetestproductionsofblankholderforce,12typicalVBHFcurveswereappliedtoperformthesimulationtestsbythesimulationsoftwareofDYNAFORM.ThesimulationtestresultsshowedthatVBHFhadgreateffectsondrawingformabilityofhot-galvanizedsheetsteelduringtherectangularboxdrawing.However,thedifferentVBHFcurveswereappliedtocontrolthewholedrawinganditwouldgetgreatdifferenteffects.Atthesametine,theVBHFhadgreateffectsonthemaximumthickthinningratio,buthadlittleeffectonthemaximumthickincrassationratio.So,reasonableapplicationoftheVBHFwouldgreatlydecreasethefractures.WhentheVBHFprofileistakenascurveL,thebesteffectofdrawingformabilitycouldbeobtained.WhencurveIisused,contraryeffectcouldbegotten.TheothertypesofcurveswouldcauseeffectsbetweenabovetwotypesofVBHFcurves.Finally,theactualtestswereappliedtocheckthevalidityoftheFEMsimulationtests.TheresultsshowthattheFEMsimulationtestsaregoodwaysforpredictingandoptimizingtheVBHF.