抗坠毁整理Word文档格式.docx
《抗坠毁整理Word文档格式.docx》由会员分享,可在线阅读,更多相关《抗坠毁整理Word文档格式.docx(23页珍藏版)》请在冰豆网上搜索。
AHS2010-0000823
0444
AHS2005-0002385
AHS2007-0000096
AHS2008-0002867
AHS2009-0000307
AHS2009-0001478
AHS2009-0001489
AHS2009-0001849
AHS2009-0002129
AHS2010-00004010
AHS2010-00004011
AHS2010-00007111
AHS2010-00013812
起落架12
AHS2007-00002512
座椅13
04013
04114
AHS2005-00025215
AHS2005-00029015
AHS2009-00014415
AHS2010-00006916
油箱16
AHS2008-00037916
AHS2009-00017217
AHS2010-00019818
机身
042
用MSC.Dytran建立的SikorskyACAP模型包括了4000节点,7000个单元,其中有3000梁单元和杆单元,3000个四边形壳单元和1000个三角形壳单元。
碰撞面用250个实体单元组成。
34种不同的材料来表示组合材料。
模型和撞击面的Mastersurface和slavenode接触也进行了定义。
MSC.DytranModeloftheSikorskyACAPHelicopter,Thefinalhelicoptermodelconsistedof4,000nodesand7,000elements,including3,000beamandrodelements,3,000quadrilateralshellelements,and1,000triangularshellelements.Theimpactsurfacewasrepresentedusing250solidelements.Thirty-fourdifferentmaterialpropertycardswereusedtorepresentavarietyofcompositelaminates.Amaster-surfacetoslave-nodecontactwasdefinedbetweenthestructuralmodelandtheimpactsurface.
在仿真中,分两阶段建模,在机身接触地面前的0.045秒,飞机起落架变形,机身视作刚体,其间机身所有节点的位置和速度输出到文件,这些数据决定了随后的可变形机身的初始状态。
该种刚体—柔性体的方法节省了cpu时间,定义为刚体时也使得引入俯仰角变得更为容易。
Toperformthesimulation,atwo-stagemodelingapproachwasemployedinwhicharigidstructuralmodelofthehelicopterwasexecutedduringdeformationofthelandinggear.At0.045secondsbeforefuselagecontact,thex-,y-,andz-locationsofallgridpointsandthecorrespondingnodalvelocitiesintherigidmodelwereoutputtoafile.Theseinitialconditionsweretheninputasthestartingpointoftheflexiblemodelsimulation.Thisrigid-to-flexibleapproachwasusedtosignificantlydecreasetheCPUtimerequiredtocompletethesimulation,andbecausetherigidmodelmadetheintroductionofthepitchangularvelocityeasier.
总的来说,试验和仿真结果一致,仿真准确的模拟了底部破碎的区域的位置和面积以及用来支撑顶部转子的一根梁的破坏,在±
0.007秒之间能较准确的模拟,但是机尾的一处破坏却没有预测到,这是因为在0.045秒之前把机身视作刚性体的缘故。
Ingeneral,reasonablygoodagreementwasobtained.Thesimulationpredictedthelocationandamountofmaximumcrushinginthesubfloorandfailureofoneofthebeamsusedtosupporttherotortransmissionoverheadmass.Thesimulationpredictedthetimingofmajoreventswithin±
0.007seconds.However,becauseatwo-stagemodelingapproachwasusedinwhichthestructuralmodelwassimulatedusingrigidmaterialpropertiesforthefirst0.045s,thefailureofthetail,seeninFigure4(b),wasnotwellpredicted.ComparisonsofselectedtestandanalysisfilteredaccelerationresponsesareplottedinFigure5.Theseresultsshowreasonablecorrelation,thoughthemagnitudeand/ortimingofthepeakaccelerationsdonotagreeexactly
在仿真中产生了几个比较重要的问题关系到该程序的应用性,首先是起落架问题,把起落架机构装到有限元机体上就耗费了大量时间,在布置起落架使所受力曲线更光滑的时候也遇到了问题。
ThemodelingoftheSikorskyACAPfull-scalecrashtestillustratedseveralimportantissuesregardingthesuccessfulapplicationofnonlinear,explicitfiniteelementcodes.Thefirstissueinvolvedmodelingofthelandinggear.Considerabletimewasspentattemptingtocoupleamechanisticmodelofthelandinggeartothefiniteelementmodeloftheairframe.Problemsaroseintryingtoalignthegearsandtomitigatethelargespikeinforcethatwasinputintothefiniteelementmodelatimpact.
LS-DYNA接触模拟,美国海军因为大量飞机坠落在水面上所以很关心该类问题,从而大力赞助水面冲击方面的科研。
总体而言飞机坠落在水面或者软土比坠落在硬地面的机理复杂得多。
LS-DYNAFluid-StructureInteractionSimulationTheU.S.Navyisconcernedwiththecrashsafetyofitshelicopterfleetduetothelargenumberofcrashesthatoccuronwater.Asaresult,theNavyhassponsoredresearchprogramstoimprovethecrashsafetyofrotorcraftduringwaterimpacts.Ingeneral,thestructuralresponseandloadtransfermechanismsforwaterandsoftsoilimpactsaremuchdifferentthanthoseonhardsurfaces.
AHS2007-000029
(本文主要介绍了SPH--smoothed-particlehydrodynamics方法在直升机撞击水面试验中的结果借助有限元进行处理),
2005年建立了一个研究小组来推动SPH在直升机撞击水面中的应用,他们制作了一个三角形截面的样本并与水面撞击,用传感器收集压力,加速度数据,用SPH法模拟液体区域。
(abstract)In2005,aGroupforAeronauticalResearchandTechnologyinEurope(GARTEUR),theAG15,wasestablishedtoimprovetheSPHmethodforapplicationtohelicopterditching.Inthisframework,waterimpactdroptests,usingatriangularcross-sectionspecimenwerecarriedoutatPolitecnicodiMilanoinordertocollectreliabledatafornumericalmodelsvalidation.Impactdecelerationsandpressuresweremeasured.Apressuretransducersuitabletomeasureimpactpressureswasdeveloped.Hence,thenumericalmodelwasworkedoutadoptingtheSPHmethodtomodelthefluidregion.
研究分两个阶段:
实验阶段和数值阶段。
首先做真实的模型撞击水面的实验并收集加速度,压力数据,在数值阶段,通过SPH方法分析结果来模拟液体区域。
Theresearchonwaterimpactconsistedoftwophases:
experimentalphaseandnumericalphase.Intheexperimentalphase,anintensetestcampaignwascarriedoutandimpactdecelerationsandpressureswereacquired.Inparticular,asuita