




已閱讀5頁,還剩12頁未讀, 繼續(xù)免費(fèi)閱讀
版權(quán)說明:本文檔由用戶提供并上傳,收益歸屬內(nèi)容提供方,若內(nèi)容存在侵權(quán),請進(jìn)行舉報(bào)或認(rèn)領(lǐng)
文檔簡介
Computer-AidedCivilandInfrastructureEngineering23(2008)448464INDUSTRIALAPPLICATIONDynamicResponseofaRolloverProtectiveStructureDavidP.Thambiratnam&BrianJ.ClarkSchoolofUrbanDevelopment,FacultyofBuiltEnvironment&Engineering,QueenslandUniversityofTechnology,Brisbane,Australia&NimalJ.PereraSchoolofUrbanDevelopment,FacultyofBuiltEnvironment&Engineering,QueenslandUniversityofTechnology,Brisbane,AustraliaRobertBirdGroup,Brisbane,AustraliaAbstract:RollOverProtectiveStructures(ROPS)aresafetydevicesfittedtoheavyvehiclestoprovideprotectiontotheoperatorduringanaccidentalrollover.Atpresent,ROPSdesignstandardsrequirefull-scaledestructivetest-ingthatcanbeexpensive,timeconsuming,andunsuitableforsmallcompanies.Moreeconomicalanalyticalmeth-odsarenotpermittedduetoalackofunderstandingofpostyieldbehaviorandtheenergyabsorptioncapacityofROPS.Toaddressthis,acomprehensiveresearchprojectwasundertakentoinvestigateROPSbehaviorusingan-alyticaltechniquessupportedbyexperiments.Thisarti-clepresentsthedynamicimpactanalysisofabulldozerROPSusingcalibratedfiniteelementmodels.Resultsindi-catethat(1)ROPSpostshavesignificantinfluenceontheenergy-absorbingcapacity,(2)dynamicamplificationsinenergycouldbeupto25%,(3)stifferROPScausehighpeakdecelerationsthatmaybedetrimentaltotheoperator,and(4)analyticaltechniquesmaybeusedforevaluatingROPSperformance.1INTRODUCTIONHeavyvehiclesthatareusedintherural,mining,andconstructionindustriesaresusceptibletorolloversasTowhomcorrespondenceshouldbeaddressed.E-mail:.au.theyhaveahighcenterofgravityandcommonlyop-erateonslopinganduneventerrain.Asteelmoment-resistingframewitheithertwoorfourpostsisusuallyattachedtothesevehiclesabovetheoperatorscabinforprotectionduringrollovers.ThissafetydeviceiscalledaRolloverProtectiveStructure(ROPS)anditsroleistoabsorbsomeofthekineticenergy(KE)oftherollover,whilemaintainingasurvivalzonefortheoperator.ThedesignandanalysisofROPSiscomplexandrequiresdualcriteriaofadequateflexibilitytoabsorbenergyandadequatestiffnesstomaintainasurvivalzonearoundtheoperator.EvaluationtechniquesusedinthecurrentAustralianstandardforearthmovingmachineryprotectivestruc-turesAS22941997aresimplifiedandinvolvefull-scaledestructivetestingofROPSsubjectedtostaticloadsalongtheirlateral,vertical,andlongitudinalaxes.Thestandardisperformancebased,withcertainforceandenergyabsorptioncriteriathatarederivedfromempir-icalformulaerelatedtothetypeofmachineandoper-atingmass.Deflectionrestrictionsarealsoemployedtoenableasurvivalspaceknownasthedynamiclimitingvolume(DLV)tobemaintainedforthevehicleoperator.Thesesimplifiedprovisionsprovidedesignguidelinesthatwillsubstantiallyimprovetheoperatorschancesofsurvivalduringanaccidentalrollover.Thisformofcerti-ficationcanbetimeconsumingandextremelyexpensiveC2008Computer-AidedCivilandInfrastructureEngineering.PublishedbyBlackwellPublishing,350MainStreet,Malden,MA02148,USA,and9600GarsingtonRoad,OxfordOX42DQ,UK.Dynamicresponseofarolloverprotectivestructure449asestablishingtheforceandenergycriteriacaninvolvelargeloadsthatmaythereforerequiretheuseofaspe-cializedtestingfacility.CertificationofROPSbymoreeconomicalanalyti-calmodelingtechniquesiscurrentlynotpermittedbyROPSstandardsforearthmovingmachinerybothinAustraliaandinternationally.Reasonsfortheexclusionareattributedtoalackofknowledgeandresearchin-formationonthebehaviorofthesestructuresinthepostyieldregionandtheirenergy-absorptioncapacity.Pre-liminaryresearchhasshownpromisefortheuseofan-alyticaltechniquestomodelthenonlinearresponseofROPS.Theseanalyticalmethodswereverysimplifiedandinvolvedtheuseofelasto-plasticbeamelementstosimulatethebehaviorofROPSsubjectedtoastaticlateralload.Inrecentyears,substantialadvanceshavebeenmadeinbothcomputationalpowerandtheimple-mentationofadvancedelementtypesinFiniteElement(FE)techniquesthatcanaccuratelymodelandpredictthenonlinearresponseofstructures,particularlyinthepostyieldregion.ResearchcarriedoutonROPSbehav-iorusinganalyticalandexperimentaltechniquesincludethoseofClarketal.(2006a,b),KimandReid(2001),Tomasetal.(1997),Swan(1988),andHuckleretal.(1985).AcomprehensiveresearchprojectwasundertakenattheQueenslandUniversityofTechnologytoinves-tigateROPSbehaviorusingcomputersimulationssup-portedbyexperimentsto(1)enhanceourunderstandingofROPSbehavior,(2)improveenergyabsorptionandsafety,and(3)generateresearchinformationtofacili-tatethedevelopmentofanalyticaltechniquesfordesignandevaluationthatmaylessentheneedfordestructivefull-scaletesting(Clark,2006a).ThisarticletreatsthedynamicresponseoftheROPSmodelforaK275bulldozer,usingcalibratedFEmodels.TheexperimentaltestingandcalibrationofthecomputemodelofthisparticularROPSmodelarereportedelse-where(Clark,2006a,b).Thedynamicimpactloadsarecharacteristicofthosethatareexperiencedduringthesidewardsrolloverofavehicleonafirmslope.Asim-plifiedmethodbasedonaconservationofangularmo-mentumapproachreportedbyWatson(1967)isusedtoestimatethedynamicimpactparametersfortheROPSduringasidewardsoverturn.TheexplicitFEcodeLS-Dynav970wasusedtoconductthenecessarydynamicimpactmodelingforrolloverimpactsonfirmslopeswithinclinationsof15,30,and45.Theinfluenceofcon-trollingvariablessuchasROPSstiffness,impactveloc-ity,anddurationandrollslopeangleonthedynamicresponseoftheROPSwasstudied.Theresultsarecom-paredwiththosefrompreviousstaticanalysistoestab-lishtheeffectofpossibledynamicamplificationsandtheadequacyofcurrentstandardprovisions.1.1DynamicfiniteelementanalysisRolloversimulationusingFEanalysishasreceivedlit-tleattentionfromresearchers.Chouetal.(1998)high-lightedthatthemajordifficultyassociatedwithusingFEforrolloveranalysiswasthelargesimulationtimerequiredtocapturetheeventaccurately.Indirectparal-leltothis,Klose(1969)alsoemphasizedthattherolloverprocesswasextremelydifficulttomodelasitinvolvedthecomplexinteractionofnumerousparametersthatinfluencedthebehavioroftherollingvehicle.Intheopenliterature,theFEmodelingofrolloverprotectivestructuresunderdynamicloadinghasbeenlimitedtore-searchperformedbyTomasetal.(1997)andHarrisetal.(2000).TheworkperformedbyHarris(2000)examinedtherearwardrolloverofatractorwhereasTomassre-searchusedtheprogramMADYMOtostudytheeffectofROPSstiffnessandoccupantrestraintduringtheside-wardsrolloverofanearthmovingmachine.AlthoughthemodelingtechniquesemployedbyeachoftheseauthorshaveassistedwithassessingtheperformanceofROPSundersimulateddynamicimpactloads,littlecompari-sonhasbeenmadewithreferencetotheadequacyofthestaticloadingproceduresadoptedincurrentROPSstan-dardsandthepossibledynamicamplificationsthatmaytakeplaceduringsuchloadingconditions.WiththeseviewsinmindthesimplifiedprocedureproposedbyWat-son(1967)isusedasabasisforadynamicimpactstudytoinvestigatetheinfluenceofcriticalparametersthatcon-troltheresponsebehaviorofROPSsubjectedtosuchloadingconditions.2ROPSFORK275BULLDOZERTheK275bulldozerisacrawlertypedozerwithagrossvehicleweightofapproximately50tonscommonlyusedintheconstructionandminingindustriesforearthmov-ingpurposes.Rolloverprotectionfortheoccupantisaf-fordedthroughatwopostrollbartypeROPS,whichisshowninFigure1.ThisROPSisprimarilyafixedbaseportalframe,con-sistingoftwopostsandabeam,rigidlyconnectedtothechassisofthevehicle.InadditiontotheROPS,anaddi-tionalroofcanopysectionknownastheFallingObjectProtectiveStructure(FOPS),isincorporatedtoprovideprotectiontotheoperatorunderfallingobjects.Inthisstudy,theFOPS,whichisaseparatedetachablestruc-ture,wasomitted.Theoverallgeometryofthefull-scaleK275ROPSmodelwasestablishedfromsitemeasure-mentstakenatthemanufacturersstorageyard.Appro-priateRHS/SHSmembersizeswereselectedsothattheROPSwouldpossesssufficientstrengthandenergyab-sorptioncharacteristicsthatwouldenableittosuccess-fullypasstherequirementsoftheAustralianStandard.450Thambiratnam,Clark&PereraFig.1.K275bulldozerwithROPS.2.1Half-scaleROPSmodelPreviousresearchbySrivastavaetal.(1978)hasshownthatprinciplesofsimilitudemodelingcouldbesuccess-fullyappliedtoROPStestingtechniques,andcouldleadtolarge-scaleeconomicsavings.BasedontheresearchfindingsoftheseauthorstheprinciplesofsimilitudewereappliedtotheK275bulldozerROPStolessenfabrica-tioncostsandreducethemagnitudesofthetestloadstobeappliedtotheROPS.Reductioninthemagnitudesoftheloadswasessentialasafull-scaletestofROPSforavehiclesuchasthiswasextremelylargeandwouldre-quiretheuseofanextensivelaboratorytestingfacility.Ascalingfactor(forsize)wasthenselectedbetweenthemodelandprototypethatgaverisetothescalingfactorsof1/8forenergyabsorbedunderlateralload,1/4forloads,and1/2fordeflections.Ahalf-scalemodeloftheK275ROPSwithlength1,000mm,height900mm,andsectionproperties125755mmforthepostsand1251255mmforthebeam,wasdesignedandfabricatedandsubjectedtotheloadingandenergyre-quirementsofAS22941997.ThemembertypesusedfortheROPSconsistedof350gradeRHSwithfullpenetrationbutt-weldedmoment-resistingconnections.Thehalf-scaleK275ROPSmodelwasexperimentallytestedundertherequiredlateral,vertical,andlongitu-dinalloads(Clark,2006a).Theloadandenergymagni-tudesestablishedfromAS2294.21997weremodifiedtotakeintoaccountthesimilituderelationshipsestablishedforthismodel.Strainanddeflectionmeasurementswererecordedforeachloadingsequence.TheexperimentaltestingwasfollowedbyFEanalysisofthehalf-scaleROPSmodelunderthesameloads,us-ingtheprogramABAQUSstandardv6.3.ScalinglawsfromthesimilitudestudyalongwiththeprogramMSCPatranwereusedtodevelopthenecessarygeometryfortheFEmodel.Figures2and3showtheexperimentaltestingoftheROPSmodelunderlateralloadandtheFEmodelofFig.2.LateralloadtestingofK275ROPS.thesameROPS,respectively.Therectangularportion(inlightershade)atthetopright-handpostintheFEmodelshowstherigidbodyusedtoapplythedynamicimpactloadingdescribedlateroninthearticle.Thelat-eralloaddeflectionplotsobtainedexperimentallyandfromtheFEanalysisshowninFigure4demonstrateexcellentagreementbetweenthetwosetsofresults.ThevariationofthestresswithloadatthebaseoftheROPSpost(acriticalregion),alsoshowedexcellentagreementbetweentheexperimentalandanalyticalre-sults(Clark,2006a).ThiscalibratedFEROPSmodelwasusedforthedynamicanalysisunderlateralimpactloads.Fig.3.FiniteelementmodelofK275ROPS.Dynamicresponseofarolloverprotectivestructure451Fig.4.Lateralloaddeflectionresponsefromexperiment(LVDT1)a
溫馨提示
- 1. 本站所有資源如無特殊說明,都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請下載最新的WinRAR軟件解壓。
- 2. 本站的文檔不包含任何第三方提供的附件圖紙等,如果需要附件,請聯(lián)系上傳者。文件的所有權(quán)益歸上傳用戶所有。
- 3. 本站RAR壓縮包中若帶圖紙,網(wǎng)頁內(nèi)容里面會(huì)有圖紙預(yù)覽,若沒有圖紙預(yù)覽就沒有圖紙。
- 4. 未經(jīng)權(quán)益所有人同意不得將文件中的內(nèi)容挪作商業(yè)或盈利用途。
- 5. 人人文庫網(wǎng)僅提供信息存儲(chǔ)空間,僅對用戶上傳內(nèi)容的表現(xiàn)方式做保護(hù)處理,對用戶上傳分享的文檔內(nèi)容本身不做任何修改或編輯,并不能對任何下載內(nèi)容負(fù)責(zé)。
- 6. 下載文件中如有侵權(quán)或不適當(dāng)內(nèi)容,請與我們聯(lián)系,我們立即糾正。
- 7. 本站不保證下載資源的準(zhǔn)確性、安全性和完整性, 同時(shí)也不承擔(dān)用戶因使用這些下載資源對自己和他人造成任何形式的傷害或損失。
最新文檔
- 2025屆云南省尋甸縣第五中學(xué)高二化學(xué)第二學(xué)期期末教學(xué)質(zhì)量檢測試題含解析
- 安徽省江淮名校2025年高一下化學(xué)期末監(jiān)測模擬試題含解析
- 浙江省金華市磐安縣第二中學(xué)2025屆高二化學(xué)第二學(xué)期期末監(jiān)測模擬試題含解析
- 2025屆內(nèi)蒙古巴彥淖爾市臨河區(qū)三中化學(xué)高一下期末綜合測試模擬試題含解析
- 河南禽類交易管理辦法
- 擬像權(quán)力批判-洞察及研究
- 醫(yī)療項(xiàng)目預(yù)算管理辦法
- 民兵物資倉庫管理辦法
- 華為公司采購管理辦法
- 我國物價(jià)運(yùn)行分析及應(yīng)對策略探討
- 第四單元整體教學(xué)設(shè)計(jì)-部編版語文八年級下冊
- 貴州省畢節(jié)市威寧縣2024年統(tǒng)編版小升初考試語文試卷(原卷版)
- 平安產(chǎn)險(xiǎn)湖北省中央財(cái)政水稻種植保險(xiǎn)條款
- 日語考試N5試題
- 農(nóng)商銀行考試題庫100題
- 電池的歷史與發(fā)展
- 小學(xué)學(xué)業(yè)生涯規(guī)劃與目標(biāo)
- 2023年CQE客訴工程師年度總結(jié)及下年規(guī)劃
- 國家開放大學(xué)《中國法律史》形成性考核1
- 攪拌類設(shè)備單機(jī)試車原始記錄
- 老舊小區(qū)物業(yè)投標(biāo)方案(技術(shù)標(biāo))
評論
0/150
提交評論