appropriatelyscaleup

scaleup  时间:2021-03-28  阅读:()
SCALE-UPOFWINDTURBINEBLADES–CHANGESINFAILURETYPEIntroductionThenextgenerationbladesfortheEuropeanoffshoremarketwillbebetween75and85mlongweightingbetween30and45tonnes.
ThemostpublicavailableexampleofthisisthenewVestasV164witha80mblade,butalsoDSME/DeWind,Samsung,AlstomandNordexaredevelopingturbineswithsimilarbladelengths.
LMWindpowerwillintroducetheirnew74mblademid2013.
Withthisnewgenerationofwindturbinebladestypicalfailuremodesaswellastheirlocationwillchange.
Forexample,theincreasinglengthandweightmakesthegravityintroducedloadsmoreimportant.
Afirst,ratherrudimentarysummaryisshowninthematrixgiveninFigure1.
Inthefourcolumnstotherightisgivenagradeindicatinghowcriticalthe(failure)modeisexpectedtobeforthegivenbladelength.
5indicatessignificantimportanceand0noimportance.
Figure1.
Trendandchangesin(failure)modesofwindturbinebladesduetoscaling.
Risbladelength.
Basedonscalinglawse.
g.
fromEU-Upwindprojectwhich,seeref.
[3]orSandiareport,ref.
[2]different(failure)modesarerelevantforthedesigndependingofthesize.
E.
g.
therootbendingmomentscale-upwithpowerof4tothebladelength(R),causedbytheincreasedmass.
Forsmallbladesitisthetipdeflection(globalstiffness)whichiscriticalandnottheweight.
Forlargerbladesthischangesanddesignershavealteredtheirfocusondecreasingtheweightutilizing,atleastpartially,lowweight/high-stiffnesscomposites(e.
g.
CFRP)tocopewithit.
Thisisgenerallyacceptedintheindustrywhentheyscale-upablade,theyhaveaclearfocusondecreasingtheweightinordertodecreasecriticaledgewisefatigueloads.
Justafewyearsbackwithsignificantlysmallerbladesaerodynamicloadsbuild-upthedominatinganddimensioningloadcasewhiletodaywithlongerbladesitisthegravitationalforcesandthereforetheweightoftheblades.
Thisoverviewoffailuremodesandhowtheyarelinkedtothescalinglaws.
Recommendationsarepresentedonhoweachfailuremodeshouldbeaddressedeitherinthedesignphasee.
g.
byanexperimentalprogramoradvancednon-linearnumericalsimulations,sincenotallarecoveredbytheinternationalstandardstoday,ref.
[4][5][7].
TypicalfailuremodesinfluencedbyscalingTransversesheardistortionofthecrosssectionThecombinationoflargeedgewiseloadsandextremeaerodynamicforcesresultinloadcombinationswhichcouldendupintoacriticaltransversesheardistortionfailure(cf.
Figure2)forscaled-upslenderblades,seeref.
[1].
Figure2.
Numericalsimulationshowstransversesheardistortionofacrosssectionloadedinacombinededge-andflapwisedirection.
Thisfailuremechanismbecomesmoreimportantwhenthesize(andweight)ofthebladesincreasemainlyduetolargergravityforcesinedgewisedirection.
Today,thefailuremodeisnotappropriatelycoveredinnowadayscertificationrules,sincenocombinationoftheforcesarerequiredinthefinalfull-scaletest.
Furthermore,theloadsareappliedthebladeusingclampswhichsupportthestructureinawaysoitcannotdistortatthisspecificcross-sections.
Failureinthecap(s)causedbyBrazierloadsTheout-of-planedeformation(flattening)ofthecaps,causedbytheBrazierloads,maycausefailureinthecaps,seeref.
[8],[10].
Thefailurecaneitherbeatransversetensionfailureintheunidirectionallayersatthebottomlayeroraninterlaminarshearfailurebetweenthelayers,seeFigure3a.
Atypicallay-upisnotparticularlywellsuitedtoreducecapdeflectionssincethefibresaretheremainlyplacedinthelongitudinaldirectionoftheblade.
Thelackoffibresinthetransversedirectioncausesthecaptoberelativelyflexibleinthelateraldirection.
Whenthecapdeflectsthereisariskoftransversetensionfailureintheunidirectionallaminates.
Inaddition,itiscommonthatmanufacturingimperfections,seeFigure3c,insidethelaminatefurtherreducethefatigueandultimatestrengthofthelaminate.
bacFigure3.
Interlaminarshearfailureoftheload-carryingcaplaminatecausedbythenon-linearBrazierforcesa)Sketchofcapdeformationandfailurebetweenlayersb)Photoofacapwithdelaminationc)Photoofacapwithamanufacturingdefect.
Whenthebladesscale-upthelongitudinalcurvatureofthebladeincrease,whichresultsinalargercrushingpressure,calledBrazierforces.
Thisresultsinlargerout-of-planedeformationoftheloadcarryingcaplaminate,whichthenresultineithertransversetensionfailureintheunidirectionallayersorinterlaminarfailure.
Thisout-of-planedeformationisanon-lineargeometricphenomena,whichunfortunately,isnotcoveredbytheinternationallydesignstandards.
Theteststandardsdonotrequirethatthereisstraingaugesmeasurement,butthisstronglyrecommendedinfuturefull-scaletest.
BucklingBucklingisastructuralnon-lineargeometricinstabilityphenomenonwhichisimportantfordesignofnowadaysandfuturewindturbineblades.
Thebucklingcapacitycaneitherbeaddressedbyanon-lineargeometricFE-analysisoralineareigenvaluebucklinganalysis.
Accordingly,linearbucklinganalysisisaguidelineforthedesignload,towhichasuitablereductionfactoriscalledfor.
However,thecorrespondingbucklingmodesneedtobeexaminedcarefully,tosortoutunrealisticmodesatunrealisticbucklingloads.
Duetotheup-scalingofbladesthetrailingedgeaswellathelargetrainingedgepanelswillbecomemorepronetodifferentkindofasdetailedinFigure4.
Figure4.
Bucklingofthetrailingedge.
Bucklingofthetrailingedgehastovalidatedinfull-scaletestbutthemethodofapplyingtheloads,maynotgivearealisticpicturesincetheclampscanbeseenasartificialboundaries,influencingthesocalled"freelength"andimpactthebucklingloadsexaminedduringtest.
AsanalternativetothemethodsRisDTUhasdevelopedamethod,usinganchorplates,whichgiveamorerealisticloadintroductionwithoutsupportingthestructure,seeref.
[9].
FailureintheadhesivebondlinesOut-of-planedeformationsofthetrailingedgepanels(alsonoticeablegrowingbyscalingtheblade)areimportantsincetheyresultinpeelingstressesinthebondlines,whichmaybethemainreasonforfatiguefailureintrailingedgeadhesivejoints,seeFigure5aswellasref.
[9].
Itiswell-knownfromtheliteraturethatbondlineshavealowstrengthwhenexposedtopeelingstressescomparedtotheotherloadingdirections,e.
g.
thefractureenergyisapproximatelyafactor8-10higherformode2(shearing)thanformode1(peeling)loading.
Figure5.
Sketchofthetrailingedgeshellswithout-of-planedeformations.
Thecloseupsshowfailureatthetrailingedgeaswellasdebondingoftheouterskinontheboxgirder.
Theloadintroductionproblematic,describedinthepreviousbucklingsection,isthesameforthisfailuremodeandalsotheanchorplatesolutionisrecommendedinfuturetesting.
FatigueproblemintheroottransitionareaInthetransitionzonefrommax.
chordtothecylindricandstiffrootregionoftencauseproblems,seeFigure6.
Thereasonthatlargeedgewiseforceshavetobe"carried"throughlargecurvedpanels,whichresultsin"pumping"out-of-planedeformationsandthengivepeelinginbondlinewherethetrailingedgepanelsareconnectedtothecylindricalroot.
Figure6.
Photoshowingaclassicalfatiguefailureinthetransitionareafrommax.
chordtotheroot.
Thefailureiscausedbytheout-of-planedeformationsofthelargetrailingedgepanels,whichissometimescalled"pumping".
Sincetherootbendingmomentscale-upwithpowerof4tothelength,thisfatiguefailureistobeextremelycriticallyforfuturewindturbineblades.
Specialdesignspecificconsiderations/modificationsneedtobetakeninaccountduringthesizingprocess.
WebfailureWebfailureshasinsomecasesbeenobservedtobethemainreasonforcollapse,seeref.
[8].
Figure7presentsafrozenframepictureofthefirst,andcritical,failuremodeobservedinafull-scaletestofaloadcarryingboxgirder.
InFigure7thewhitecircle(lightgreencolour)initialfacedebondingoftheouterskinontheshearweb'ssandwichsectionareshown,leadingtoultimatecollapseoftheboxgirder,seeref.
[8]Figure7.
Skindebondingfailureofthesandwichshearwebswhichwasobservedinafull-scaletestofaloadcarryingboxgirder,seeref.
[8].
Thisfailurecouldbedueto,tooweakskinfacesinthesandwichshearwebs.
Thisfailurewouldnormally,notbeobservedinacommercialfull-scaletestsinceitisalmostimpossibletoaccessbothsidesoftheshearwebwithmeasuringequipment,camerasetc.
.
IntheFE-modelingwhichsometimesisrequiredbythecertificationbodies,thisfailuremodeisnoteasytoaddresssinceitwouldrequireonafracturemechanicsapproach.
Furthermore,anon-lineargeometricanalysisisrequiredotherwisetheBraziercrushingforceswillnotbeincluded,andthis,asmentionedearlier,isnotpartofastandardcertificationprocess.
AsmentionedearliertheBrazierforcesareexpectedtobemoredominantwhenthebladesscalesupandthereforealsothiswebfailuremodehavetobeconsideredmorecarefullyinthefuture.
References[1]Jensen,F.
M.
"Ultimatestrengthofalargewindturbineblade",Ris-PhD-34(EN),PhDthesis,RisNationalLaboratoryforSustainableEnergy,TechnicalUniversityofDenmark,(2008).
[2]Griffin,D.
T.
andAshwill,T.
D.
"TheSandia100-meterAll-glassBaselineWindTurbineBlades:SNLSNL100-00"Sandiareport,June2011[3]Lekou,D.
J.
"UpWindreport"Scalinglimits&CostsRegardingWTBlade"EU-Upwindproject2010(www.
upwind.
eu)[4]GuidelinefortheCertificationofOffshoreWindTurbines.
GermanischerLloydWindEnergieGmbH.
(June2005)[5]DNVStandardDNV-OS-J102-DesignandManufactureofWindTurbineBlades.
DetNorskeVeritas(October2010)[6]Jensen,F.
M,Srensen,J.
D.
,Nielsen,P.
,Berring,P.
,FloresP.
.
"FailuresinTrailingedgebondlinesofwindturbineblades"32ndRisInternationalSymposiumonMaterialsScience2011[7]IEC61400-1.
Windturbines-Part1:Designrequirements.
3rdedition.
(2005)[8]JensenF.
M.
,WeaverP.
M.
,CecchiniL.
S.
,StangH.
,NielsenR.
F.
,"TheBrazierseffectinwindturbinebladesanditsinfluenceondesign"WindEnergyJournal2011.
DOI:10.
1002/we.
473[9]JensenF.
M.
,SrensenJ.
D.
,NielsenP.
H.
,BerringP.
,FloresS.
,"Failuresintrailingedgebondlinesofwindturbineblades".
WindEnergyDivision,RisNationalLaboratoryforSustainableEnergy,TechnicalUniversityofDenmark.
(RisDTUSymposiumSeptember2011)[10]JensenF.
M.
,PuriA.
,DearJ.
P.
,BrannerK.
,MorrisJ.
,"Investigatingtheimpactofnon-lineargeometricaleffectsonwindturbinebladesPart1:Currentdesignstatusandfuturechallengesindesignoptimization",(WindEnergyJournalAugust2010-DOI:10.
1002/we.
415).
DOI:10.
1002/we.
415[11]KlingA.
,TessmerJ.
,DegenhardtR.
,"ValidationProcedureforNonlinearAnalysisofStringerStiffenedCFRPPanels",Proceedingsofthe25thCongressofInternationalCounciloftheAeronauticalSciences",Hamburg,Germany,3-8September,2006

器安装环境和运维管理工具推荐

今天看到一个网友从原来虚拟主机准备转移至服务器管理自己的业务。这里问到虚拟主机和服务器到底有什么不同,需要用到哪些工具软件。那准备在下班之间稍微摸鱼一下整理我们服务器安装环境和运维管理中常见需要用到的软件工具推荐。第一、系统镜像软件一般来说,我们云服务器或者独立服务器都是有自带镜像的。我们只需要选择镜像安装就可以,比如有 Windows和Linux。但是有些时候我们可能需要自定义镜像的高级玩法,这...

Hostinger 限时外贸美国主机活动 低至月12元且赠送1个COM域名

Hostinger 商家我们可能一些新用户不是太熟悉,因为我们很多新人用户都可能较多的直接从云服务器、独立服务器起步的。而Hostinger商家已经有将近十年的历史的商家,曾经主做低价虚拟主机,也是比较有知名度的,那时候也有接触过,不过一直没有过多的使用。这不这么多年过去,Hostinger商家一直比较稳妥的在运营,最近看到这个商家在改版UI后且产品上也在活动策划比较多。目前Hostinger在进...

HostKvm开年促销:香港国际/美国洛杉矶VPS七折,其他机房八折

HostKvm也发布了开年促销方案,针对香港国际和美国洛杉矶两个机房的VPS主机提供7折优惠码,其他机房业务提供8折优惠码。商家成立于2013年,提供基于KVM架构的VPS主机,可选数据中心包括日本、新加坡、韩国、美国、中国香港等多个地区机房,均为国内直连或优化线路,延迟较低,适合建站或者远程办公等。下面列出几款主机配置信息。美国洛杉矶套餐:美国 US-Plan1CPU:1core内存:2GB硬盘...

scaleup为你推荐
permissiondeniedpermission denied是什么意思啊?中老铁路中长铁路的铁路的新中国历史李子柒年入1.6亿将55g铁片放入硫酸铜溶液中片刻,取出洗净,干燥后,称重为56.6g,问生成铜多少g??求解题步骤及答案关键字什么叫关键词百度关键词价格查询如何查到推广关键词的价钱?rawtools照片上面的RAW是什么意思,为什么不能到PS中去编辑同ip域名两个网站同一个IP怎么绑定两个域名百度关键词工具如何通过百度官方工具提升关键词排名抓站工具一起来捉妖神行抓妖辅助工具都有哪些?www.03ggg.comwww.tvb33.com这里好像有中国性戏观看吧??
长春域名注册 主机评测 电影服务器 z.com unsplash realvnc 搜狗12306抢票助手 南昌服务器托管 可外链相册 100m独享 免费高速空间 美国堪萨斯 免费网页空间 吉林铁通 免费mysql数据库 跟踪路由命令 主机管理系统 qq金券 中国联通宽带测速 阿里云个人邮箱 更多