塔式起重机有限元分析外文翻译

山东建筑大学毕业设计外文文献及译文第1页FEMOptimizationforRobotStructureWangShijun,ZhaoJinjuan*DepartmentofMechanicalEngineering,Xi'anUniversityofTechnologyShaanxiProvince,People'sRepublicofChinaInstituteofPrintingandPackingEngineering,Xi'anUniversityofTechnologyAbstractInoptimaldesignforrobotstructures,designmodelsneedtohemodifiedandcomputedrepeatedly.Becausemodifyingusuallycannotautomaticallyberun,itconsumesalotoftime.ThispapergivesamethodthatusesAPDLlanguageofANSYS5.5softwaretogenerateanoptimalcontrolprogram,whichmikeoptimalprocedurerunautomaticallyandoptimalefficiencybeimproved.1）IntroductionIndustrialrobotisakindofmachine,whichiscontrolledbycomputers.Becauseefficiencyandmaneuverabilityarehigherthantraditionalmachines,industrialrobotisusedextensivelyinindustry.Forthesakeofefficiencyandmaneuverability,reducingmassandincreasingstiffnessismoreimportantthantraditionalmachines,instructuredesignofindustrialrobot.Alotofmethodsareusedinoptimizationdesignofstructure.Finiteelementmethodisamucheffectivemethod.Ingeneral,modelingandmodifyingaremanual,whichisfeasiblewhenmodelissimple.Whenmodeliscomplicated,optimizationtimeislonger.Inthelongeroptimizationtime,calculationtimeisusuallyverylittle,amajorityoftimeisusedformodelingandmodifying.Itiskeyofimprovingefficiencyofstructureoptimizationhowtoreducemodelingandmodifyingtime.APDLlanguageisaninteractivedevelopmenttool,whichisbasedonANSYSandisofferedtoprogramusers.APDLlanguagehastypicalfunctionofsomelargecomputerlanguages.Forexample,parameterdefinitionsimilartoconstantandvariabledefinition,branchandloopcontrol,andmacrocallsimilartofunctionandsubroutinecall,etc.Besidesthese,itpossessespowerfulcapabilityofmathematicalcalculation.Thecapabilityofmathematicalcalculationincludesarithmeticcalculation,comparison,rounding,andtrigonometricfunction,exponentialfunctionandhyperbolafunctionofstandardFORTRANlanguage,etc.BymeansofAPDLlanguage,thedatacanbereadandthencalculated,whichisindatabaseofANSYSprogram,and山东建筑大学毕业设计外文文献及译文第2页runningprocessofANSYSprogramcanbecontrolled.Fig.1showsthemainframeworkofaparallelrobotwiththreebars.Whenthelengthofthreebarsarechanged,conjunctendofthreebarscanfollowagiventrack,whererobothandisinstalled.Coreoftopbeamistriangle,owingtothreebarsusedinthedesign,whichisshowedinFig.2.Useofthreebarsmakestopbeamnonsymmetricalalongtheplanethatisdefinedbytwocolumns.AccordingtoaqualitativeanalysisfromFig.1,Stiffnessvaluesalongz-axisaredifferentatthreejointlocationsonthetopbeamandstiffnessatthelocationbetweenbar1andtopbeamislowest,whichisconfirmedbycomputingresultsoffiniteelement,too.Accordingtodesigngoal,stiffnessdifferenceatthreejointlocationsmusthewithinagiventolerance.Inconsistentofstiffnesswillhaveinfluenceonthemotionaccuracyofthemanipulatorunderhighload,soitisnecessarytofindtheaccuratelocationoftopbeamalongx-axis.Tothequestionspresentedabove,thegeneralsolutionistochangethelocationofthetopbeammanytimes,comparetheresultsandeventuallyfindaproperposition,Themodelwillbemodifiedaccordingtothelastcalculatingresulteachtime.Itisdifficulttoavoidmistakesiftheiterativeprocessiscontrolledmanuallyandtheiterativetimeistoolong.Theouterwallandinnerribshapesofthetopbeamwillbechangedafterthemodelismodified.Tofindtheappropriatelocationoftopbeam,themodelneedstobemodifiedrepetitiously.Fig.1SolutionofOriginalDesignThispapergivesanoptimizationsolutiontothepositionoptimizationquestionofthetopbeambyAPDLlanguageofANSYSprogram.Aftertheanalysismodelfirstfounded,theoptimizationcontrolprogramcanbeformedbymeansofmodelinginstructioninthelogfile.Thelateriterativeoptimizationprocesscanbefinishedbytheoptimizationcontrolprogramanddonotneedmanualcontrol.Thetimespentinmodifyingthemodelcanbedecreasedtotheignorableextent.Theefficiencyoftheoptimizationprocessisgreatlyimproved.2）ConstructionofmodelforanalysisThestructureshowninFig.1consistsofthreeparts:twocolumns,onebeamandthreedrivingbars.Thecolumnsandbeamarejoinedbytheboltsonthefirsthorizontalriblocatedon山东建筑大学毕业设计外文文献及译文第3页topofthecolumnsasshowninFig.1.Becausethedrivingbarsaresubstitutedbyequivalentforcesonthejointpositions,theirstructureisignoredinthemodel.Thecoreofthetopbeamisthreejointsandaholewithspecialpurpose,whichcannotbechanged.Theotherpartsofthebeammaybechangedifneeded.Fortheconvenienceofmodeling,thecoreofthebeamisformedintoonecomponent.Intheprocessofoptimization,onlythecorepositionofbeamalongxaxisischanged,thatistosay,shapeofbeamcoreisnotchanged.Itshouldbenoticedthat,intherestofbeam,onlyshapeischangedbutthetopologyisnotchangedandwhichcanautomaticallybeperformedbythecontrolprogram.Fig.1,sixboltsjointhebeamandtwocolumns.Thejointsurfacecannotbearthepullstressinthenon-boltjointpositions,inwhichitisbettertosetcontactelements.Whenthemodelincludescontactelements,nonlineariterativecalculationwillbeneededintheprocessofsolutionandthecomputingtimewillquicklyincrease.Thetrialcomputingresultnotincludingcontactelementshowsthattheoutsideofbeambearspullingstressandtheinnerofbeambearsthepressstress.Consideringtheprimaryanalysisobjectisthejointpositionstiffnessbetweenthetopbeamandth