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

FBICDN,0.1元解决伪墙/假墙攻击,超500 Gbps DDos 防御,每天免费流量高达100G,免费高防网站加速服务

最近很多网站都遭受到了伪墙/假墙攻击,导致网站流量大跌,间歇性打不开网站。这是一种新型的攻击方式,攻击者利用GWF规则漏洞,使用国内服务器绑定host的方式来触发GWF的自动过滤机制,造成GWF暂时性屏蔽你的网站和服务器IP(大概15分钟左右),使你的网站在国内无法打开,如果攻击请求不断,那么你的网站就会是一个一直无法正常访问的状态。常规解决办法:1,快速备案后使用国内服务器,2,使用国内免备案服...

久久网云-目前最便宜的国内,香港,美国,日本VPS云服务器19.9元/月起,三网CN2,2天内不满意可以更换其他机房机器,IP免费更换!。

久久网云怎么样?久久网云好不好?久久网云是一家成立于2017年的主机服务商,致力于为用户提供高性价比稳定快速的主机托管服务,久久网云目前提供有美国免费主机、香港主机、韩国服务器、香港服务器、美国云服务器,香港荃湾CN2弹性云服务器。专注为个人开发者用户,中小型,大型企业用户提供一站式核心网络云端服务部署,促使用户云端部署化简为零,轻松快捷运用云计算!多年云计算领域服务经验,遍布亚太地区的海量节点为...

DiyVM(50元起)老牌商家,香港沙田CN2直连vps/不限流量/五折终身优惠

diyvm怎么样?diyvm是一家国内成立时间比较久的主机商家了,大约在6年前站长曾经用过他家的美国机房的套餐,非常稳定,适合做站,目前商家正在针对香港沙田机房的VPS进行促销,给的是五折优惠,续费同价,香港沙田机房走的是CN2直连的线路,到大陆地区的速度非常好,DiyVM商家采用小带宽不限流量的形式,带宽2Mbps起步,做站完全够用,有需要的朋友可以入手。diyvm优惠码:五折优惠码:OFF50...

scaleup为你推荐
固态硬盘是什么固态硬盘是什么?云爆发云出十里未及孤村什么意思www.983mm.com哪有mm图片?你懂得刘祚天你们知道21世纪的DJ分为几种类型吗?(答对者重赏)冯媛甑谁知道怎么找到冯媛甄的具体资料?丑福晋爱新觉罗.允禄真正的福晋是谁?他真的是一个残酷,噬血但很专情的一个人吗?www.7788dy.comwww.tom365.com这个免费的电影网站有毒吗?百度指数词百度指数是指,词不管通过什么样的搜索引擎进行搜索,都会被算成百度指数吗?partnersonline电脑内一切浏览器无法打开广告法请问违反了广告法,罚款的标准是什么
申请免费域名 idc评测 diahosting mediafire下载 香港新世界电讯 免费博客空间 丹弗 最好的免费空间 美国免费空间 中国网通测速 鲁诺 国外ip加速器 安徽双线服务器 linode支付宝 阿里云手机官网 汤博乐 镇江高防服务器 phpwind论坛 ipower 远程登录 更多