Rotating Machinery, Vibro-Acoustics & Laser Vibrometry, Volume 7

239 Pages·2019·20.17 MB·English

by  Dario Di Maio

Conference Proceedings of the Society for Experimental Mechanics Series
Dario Di Maio Editor
Rotating Machinery,
Vibro-Acoustics & Laser
Vibrometry, Volume 7
Proceedings of the 36th IMAC, A Conference and Exposition
on Structural Dynamics 2018
ConferenceProceedingsoftheSocietyforExperimentalMechanicsSeries
SeriesEditor
KristinB.Zimmerman,Ph.D.
SocietyforExperimentalMechanics,Inc.,
Bethel,CT,USA
Moreinformationaboutthisseriesathttp://www.springer.com/series/8922
Dario Di Maio
Editor
Rotating Machinery, Vibro-Acoustics &
Laser Vibrometry, Volume 7
Proceedings of the 36th IMAC, A Conference and Exposition
on Structural Dynamics 2018
123
Editor
DarioDiMaio
FacultyofEngineering
Queen’sBuilding
UniversityofBristol
Bristol,UK
ISSN2191-5644 ISSN2191-5652 (electronic)
ConferenceProceedingsoftheSocietyforExperimentalMechanicsSeries
ISBN978-3-319-74692-0 ISBN978-3-319-74693-7 (eBook)
https://doi.org/10.1007/978-3-319-74693-7
LibraryofCongressControlNumber:2018939785
©TheSocietyforExperimentalMechanics,Inc.2019
Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartofthematerialisconcerned,specificallytherights
oftranslation,reprinting,reuseofillustrations,recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor
informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodologynowknownorhereafterdeveloped.
Theuseofgeneraldescriptivenames,registerednames,trademarks,servicemarks,etc.inthispublicationdoesnotimply,evenintheabsenceofaspecific
statement,thatsuchnamesareexemptfromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
Thepublisher,theauthorsandtheeditorsaresafetoassumethattheadviceandinformationinthisbookarebelievedtobetrueandaccurateatthedate
ofpublication.Neitherthepublishernortheauthorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinorfor
anyerrorsoromissionsthatmayhavebeenmade.Thepublisherremainsneutralwithregardtojurisdictionalclaimsinpublishedmapsandinstitutional
affiliations.
Printedonacid-freepaper
ThisSpringerimprintispublishedbytheregisteredcompanySpringerInternationalPublishingAGpartofSpringerNature.
Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland
Preface
RotatingMachinery,Vibro-AcousticsandLaserVibrometryrepresentsoneofninevolumesoftechnicalpaperspresentedat
the36thIMAC,AConferenceandExpositiononStructuralDynamics,organizedbytheSocietyforExperimentalMechanics,
and held in Orlando, Florida, February 12–15, 2018. The full proceedings also include volumes on Nonlinear Dynamics;
DynamicsofCivilStructures;ModelValidationandUncertaintyQuantification;DynamicsofCoupledStructures;Special
Topics in Structural Dynamics; Structural Health Monitoring, Photogrammetry and DIC; Sensors and Instrumentation,
Aircraft/AerospaceandEnergyHarvesting;andTopicsinModalAnalysisandTesting.
Eachcollectionpresentsearlyfindingsfromexperimentalandcomputationalinvestigationsonanimportantareawithin
structural dynamics. Topics represent papers on enabling technologies, rotating machinery, vibro-acoustics and laser
vibrometry,andadvancesinwindenergy.
Theorganizerswouldliketothanktheauthors,presenters,sessionorganizers,andsessionchairsfortheirparticipationin
thistrack.
Bristol,UK D.DiMaio
v
Contents
1 SummarizingResultsforScalingOMAModeShapesbytheOMAHTechnique................................ 1
AndersBrandt,MartaBerardengo,StefanoManzoni,MarcelloVanali,andAlfredoCigada
2 DelaminationIdentificationofLaminatedCompositePlatesUsingaContinuouslyScanningLaser
DopplerVibrometerSystem............................................................................................ 9
Da-MingChen,Y.F.Xu,andW.D.Zhu
3 RapidandDense3DVibrationMeasurementbyThreeContinuouslyScanningLaserDoppler
Vibrometers .............................................................................................................. 19
Da-MingChenandW.D.Zhu
4 ModalControlofMagneticSuspendedRotors ...................................................................... 31
Marcus Vinicius Fernandes de Oliveira, Felipe Carmo Carvalho, Adriano Borges Silva,
AldemirApCavaliniJr.,andValderSteffenJr.
5 OntheImplementationofMetastructuresinRotordynamics...................................................... 43
CarloRosso,ElvioBonisoli,andFabioBruzzone
6 AnalysisoftheDynamicResponseofCoupledCoaxialRotors .................................................... 53
AlexanderH.Haslam,ChristophW.Schwingshackl,andAndrewI.J.Rix
7 OperationalModalAnalysisofRotatingMachinery................................................................ 67
S.Gres,P.Andersen,andL.Damkilde
8 CharacterizationofTorsionalVibrations:Torsional-OrderBasedModalAnalysis............................. 77
EmilioDiLorenzo,C.Colantoni,F.Bianciardi,S.Manzato,K.Janssens,andB.Peeters
9 Long-TermAutomaticTrackingoftheModalParametersofanOffshoreWindTurbineDrivetrain
SysteminStandstillCondition......................................................................................... 91
MahmoudEl-Kafafy,NicolettaGioia,PatrickGuillaume,andJanHelsen
10 Dynamic Modelling and Vibration Control of a Turbomolecular Pump with Magnetic Bearings
inthePresenceofBladeFlexibility.................................................................................... 101
AlyssonB.BarbosaMoreiraandFabriceThouverez
11 Pushing3DScanningLaserDopplerVibrometrytoCaptureTimeVaryingDynamicCharacteristics....... 111
BryanWittandBrandonZwink
12 DynamicMeasurementsonMiniatureSpringsforFlawandDamageDetection................................ 123
DanielP.Rohe
13 UsingHigh-ResolutionMeasurementstoUpdateFiniteElementSubstructureModels........................ 137
DanielP.Rohe
14 DeterminationofRepresentativeOffshoreWindTurbineLocationsforFatigueLoadMonitoring
byMeansofHierarchicalClustering.................................................................................. 149
AndreasEhrmann,CristianGuillermoGebhardt,andRaimundRolfes
vii
viii Contents
15 EffectofFriction-InducedNonlinearityonOMA-IdentifiedDynamicCharacteristicsofOffshore
PlatformModels......................................................................................................... 153
TobiasFriis,AntoniosOrfanos,EvangelosKatsanos,SandroAmador,andRuneBrincker
16 RemoteDamageDetectionofRotatingMachinery.................................................................. 163
PeterH.Fickenwirth,CharlesH.Liang,TyrelC.Rupp,EricB.Flynn,andAdamJ.Wachtor
17 ExperimentalDemonstrationofaTunableAcoustoelasticSystem ................................................ 179
DeborahFowler,GarrettLopp,DhirajBansal,RyanSchultz,MatthewBrake,andMicahShepherd
18 NumericalModelingofanEnclosedCylinder ....................................................................... 191
RyanSchultzandMicahShepherd
19 ExploitingLaserDopplerVibrometryinLargeDisplacementTests .............................................. 199
E.Copertaro,P.Chiariotti,M.Martarelli,andP.Castellini
20 ARationalBasisforDeterminingVibrationSignatureofShaft/CouplingMisalignmentinRotating
Machinery................................................................................................................ 207
ChangruiBai,Surendra(Suri)Ganeriwala,andNaderSawalhi
21 ParametricExperimentalModalAnalysisofaModernViolinBasedonaGuarneridelGesùModel ........ 219
ElvioBonisoli,MarcoCasazza,DomenicoLisitano,andLucaDimauro
22 InfluenceoftheHarmonicsontheModalBehaviorofWindTurbineDrivetrains............................... 231
N.Gioia,P. J.Daems,C.Peeters,M.El-Kafafy,P.Guillaume,andJ.Helsen
23 TheInfluenceofGeometricalCorrelationinModalValidationUsingAutomated3DMetrology ............. 239
TarunTejaMallareddy,DanielJ.Alarcón,SarahSchneider,andPeterG.Blaschke
Chapter 1
Summarizing Results for Scaling OMA Mode Shapes by the
OMAH Technique
AndersBrandt,MartaBerardengo,StefanoManzoni,MarcelloVanali,andAlfredoCigada
Abstract Methods for scaling mode shapes determined by operational modal analysis (OMA) have been extensively
investigated in the last years. A recent addition to the range of methods for scaling OMA mode shapes is the so-called
OMAHtechnique,whichisbasedonexcitingthestructurebyharmonicforcesappliedbyanactuator.Byapplyingharmonic
forces in at least one degree-of-freedom (DOF), and measuring the response in at least one response DOF, while using at
leastasmanyfrequenciesasthenumberofmodeshapestobescaled,themodeshapescaling(modalmass)ofallmodesof
interestmaybedetermined.Inpreviouspublicationsonthemethodtheauthorshaveproventhatthetechniqueiseasyand
robusttoapplytobothsmallscaleandlargescalestructures.Also,ithasbeenshownthatthetechniqueiscapableofscaling
highlycoupledmodesbyusinganextendedmultiplereferenceformulation.Thepresentpapersummarizesthetheoryofthe
OMAHmethodandgivesrecommendationsofhowtoimplementthemethodforbestresults.Itispointedout,ashasbeen
shown in previous papers, that the accuracy of the mode scaling is increased by using more than one response DOF, and
by selecting DOFs with high mode shape coefficients. To determine the harmonic force and responses, itis recommended
to use the three-parameter sine fit method. It is shown that by using this method, the measurement time can be kept short
byusinghighsamplingfrequencyandbandpassfilteringwhereasspectrumbasedmethodsrequirelongmeasurementtimes.
This means that even for structures with low natural frequencies, the extra measurement time for scaling the mode shapes
canbekeptrelativelyshort.
Keywords Operationalmodalanalysis · OMA · Modeshapescaling · OMAH · Sineexcitation
1.1 Introduction
Operationalmodalanalysis(OMA)naturallyleadstounscaledmodeshapes,sincetheforcesactingonthestructurearenot
measured.Itisnotuncommonthatscaledmodeshapesaredesired,however.Insuchcases,severalmethodsexistbywhich
themodeshapesobtainedbytheOMAparameterextractionmaybescaled.MostofthemethodsdevelopedtoscaleOMA
modeshapescanbedividedintothefollowingcategories:
1. methodsbasedonseveralOMAtests,withdifferentmassorstiffnessconfigurations,seeforexample[1–4];
2. methodsbasedonknowingthemassmatrixofthestructure,expandtheOMAmodeshapestothesizeofthemassmatrix,
andscalethemodeshapesusingtheweightedmodevectororthogonalityproperty,see[5];
3. methods based on exciting the structure by a known force, and use this force for scaling, usually referred to as OMAX,
seeforexample[6,7].
Of the methods above, the last method has the advantage that it uses an actual measurement of the force, and is thus, in
some sense, scaling the modal model to some calibrated force value. On the other hand, it is generally difficult to excite
large structures with broadband force. The authors recently suggested to use harmonic forces for the excitation, since this
requireslessperformanceoftheactuatorused[8].Themethod,calledOMAH,wasextendedwithaglobalformulationin
A.Brandt((cid:2))
DepartmentofTechnologyandInnovation,UniversityofSouthernDenmark,OdenseM,Denmark
e-mail:[email protected]
M.Berardengo·M.Vanali
DepartmentofEngineeringandArchitecture,UniversitàdegliStudidiParma,Parma,Italy
S.Manzoni·A.Cigada
DepartmentofMechanicalEngineering,PolitecnicodiMilano,Milan,Italy
©TheSocietyforExperimentalMechanics,Inc.2019 1
D.DiMaio(ed.),RotatingMachinery,Vibro-Acoustics&LaserVibrometry,Volume7,ConferenceProceedings
oftheSocietyforExperimentalMechanicsSeries,https://doi.org/10.1007/978-3-319-74693-7_1
2 A.Brandtetal.
[9],allowingtousemultipledegreesoffreedom(DOFs)forforceaswellasresponselocations.TheglobalOMAHmethod
is therefore capable of scaling mode shapes also in cases where there is no single DOF to be chosen for excitation of all
modes.Furthermore,usingseveralresponsepointsforthescalingreducesthevarianceintheestimatesofthemodalmassof
thestructure.
Using harmonic force to scale OMA mode shapes has the advantage that it puts little demand on the actuator, as the
actuator only needs to produce a narrowband excitation. Relatively inexpensive actuators can readily be designed for
harmonic excitation – even for exciting large structures at low frequencies with relatively high force levels. Furthermore,
theestimationoftheharmonicsignal,hiddeninrandomnoisefromwind,traffic,andotherpossiblesources,canbeachieved
underpoorsignal-to-noiseratios(SNRs),withwell-knownsignalprocessingmethods(mainlytheso-calledthree-parameter
sinefitmethod),seeSect.1.2.2.
1.2 Theory
ThetheoryoftheglobalformulationoftheOMAHmethodispresentedinthissection.First,inSect.1.2.1bylayingoutthe
methodforscaling,basedonestimatesofthefrequencyresponseofthestructureatanumberoffrequencies.Secondly,in
Sect.1.2.2themethodtoaccuratelydeterminetheharmonicforceandresponsesataparticularfrequency,isdiscussed.
1.2.1 OMAH ModeShapeScaling
Scalingmodeshapesisidenticaltodeterminingthemodalmassofeachmode.Westartbyassumingafrequencyresponse
function(FRF)inreceptanceformat(displacementoverforce)betweenexcitationinDOFqandresponseinDOFp,which
canbewrittenasafunctionofangularfrequency,!,as
XN q p
H .j!/D r r (1.1)
p;q m .j!(cid:2)s /.j!(cid:2)s(cid:2)/
rD1 r r r
wherem denotesthemodalmassofmoder,and(cid:2) denotescomplexconjugate.Moreover, p and q aretheeigenvector
r r r
coefficients(fromtheOMA)formoder atDOFspandq,respectively.Thepoles,s ,aredefinedbytheundampednatural
r
frequencies(inrad/s),! ,andtherelativedampingratios,(cid:2) ,as
r r
q
s D(cid:2)(cid:2) ! Cj! 1(cid:2)(cid:2)2: (1.2)
r r r r r
Finally,jistheimaginaryunit.
After OMA parameter extraction all factors on the right-hand side are known, except the modal mass, and scaling the
modalmodelthusrequirestodeterminethemodalmassofeachmode.
The OMAH method relies on first making an OMA test, whereafter a number of frequency responses, H .j!/, are
p;q
estimatedatanumberofresponseDOFsp D p ;p ;:::;p andoneormoreexcitationDOFsq D q ;q ;:::;q .Then,an
1 2 m 1 2 v
equation system is set up to estimate the modal masses and, potentially, residual terms accounting for out-of-band modes.
Inthesimplestofcases,however,Eq.(1.1)canbeuseddirectlyemployingasingleFRFestimate,assumingasingle-DOF
approximationandnoeffectsofsurroundingmodes.
For the general case, we define a global scaling method by first assuming we wish to scale a number, g, modes, from
modenumberhtohCg(cid:2)1,usingthesetofmeasuredFRFs.WealsodefineconstantresidualtermsC (formodesbelow
pq
themodesofinterest)andD (formodesabovethemodesofinterest)byapproximatingtheFRFby
pq
H .j!/(cid:3)hCXg(cid:3)1 rp rq C Cpq CD : (1.3)
p;q m .j!(cid:2)s /.j!(cid:2)s(cid:2)/ !2 pq
rDh r r r
Next,wedefinetheFRFcolumnvectorfHg,containingmeasuredFRFs,by
l
(cid:2)
fHg D H .j! / H .j! / ::: H .j! / H .j! / :::
l p1;q1 ex;1 p1;q1 ex;2 p2;q1 ex;1 p2;q1 ex;2
Hpm;q1.j!ex;1/ Hpm;q1.j!ex;2/ ::: Hp1;q2.j!ex;1/ Hp1;q2.j!ex;2/ ::: (1.4)
(cid:3)T
H .j! / H .j! / :::
pm;qv ex;1 pm;qv ex;2