Table Of ContentConference Proceedings of the Society for Experimental Mechanics Series
Christopher Niezrecki · Javad Baqersad
Dario Di Maio Editors
Rotating Machinery,
Optical Methods
& Scanning LDV
Methods, Volume 6
Proceedings of the 37th IMAC, A Conference and
Exposition on Structural Dynamics 2019
ConferenceProceedingsoftheSocietyforExperimentalMechanicsSeries
SeriesEditor
KristinB.Zimmerman,Ph.D.
SocietyforExperimentalMechanics,Inc.,
Bethel,CT,USA
Moreinformationaboutthisseriesathttp://www.springer.com/series/8922
Christopher Niezrecki • Javad Baqersad (cid:129) Dario Di Maio
Editors
Rotating Machinery, Optical Methods
& Scanning LDV Methods, Volume 6
Proceedings of the 37th IMAC, A Conference and Exposition
on Structural Dynamics 2019
123
Editors
ChristopherNiezrecki JavadBaqersad
DepartmentMechanicalEngineering KetteringUniversity
UniversityofMassachusettsLowell Flint,MI,USA
Lowell,MA,USA
DarioDiMaio
DepartmentofMechanicalEngineering
UniversityofBristol,QueensBuilding
Bristol,UK
ISSN2191-5644 ISSN2191-5652 (electronic)
ConferenceProceedingsoftheSocietyforExperimentalMechanicsSeries
ISBN978-3-030-12934-7 ISBN978-3-030-12935-4 (eBook)
https://doi.org/10.1007/978-3-030-12935-4
LibraryofCongressControlNumber:2019936301
©SocietyforExperimentalMechanics,Inc.2019
Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartofthematerialisconcerned,specificallytherights
oftranslation, reprinting, reuse ofillustrations, recitation, broadcasting, reproduction onmicrofilms orinany other physical way, and transmission or
informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodologynowknownorhereafterdeveloped.
Theuseofgeneraldescriptivenames,registerednames,trademarks,servicemarks,etc.inthispublicationdoesnotimply,evenintheabsenceofaspecific
statement,thatsuchnamesareexemptfromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
Thepublisher,theauthors,andtheeditorsaresafetoassumethattheadviceandinformationinthisbookarebelievedtobetrueandaccurateatthedate
ofpublication.Neitherthepublishernortheauthorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinorfor
anyerrorsoromissionsthatmayhavebeenmade.Thepublisherremainsneutralwithregardtojurisdictionalclaimsinpublishedmapsandinstitutional
affiliations.
ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG.
Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland
Preface
Rotating Machinery, Optical Methods & Scanning LDV Methods represents one of the eight volumes of technical papers
presented at the 37th IMAC, A Conference and Exposition on Structural Dynamics, organized by the Society for
Experimental Mechanics, and held in Orlando, Florida, January 28–31, 2019. The full proceedings also include volumes
on Nonlinear Structures and Systems; Dynamics of Civil Structures; Model Validation and Uncertainty Quantification;
Dynamics of Coupled Structures; Special Topics in Structural Dynamics & Experimental Techniques; Sensors and
Instrumentation,Aircraft/Aerospace,EnergyHarvesting&DynamicEnvironmentsTesting;andTopicsinModalAnalysis
&Testing.
Eachcollectionpresentsearlyfindingsfromexperimentalandcomputationalinvestigationsonanimportantareawithin
structuraldynamics.
Theorganizerswouldliketothanktheauthors,presenters,sessionorganizers,andsessionchairsfortheirparticipationin
thistrack.
Lowell,MA,USA ChristopherNiezrecki
Flint,MI,USA JavadBaqersad
Bristol,UK DarioDiMaio
v
Contents
1 DetectionofSourcesofNonlinearityinMultipleBoltedJointsbyUseofLaserVibrometer................... 1
ArnaldodelliCarri,SanteCampanelli,andDarioDi Maio
2 SingleHigh-SpeedCameraBased3DDeflectionReconstructioninFrequencyDomain........................ 15
JankoSlavicˇ,DomenGorjup,andMihaBoltežar
3 OperationalModalAnalysisofaThin-WalledRocketNozzleUsingPhase-BasedImageProcessing
andComplexityPursuit................................................................................................. 19
MarcA.Eitner,BenjaminG.Miller,JayantSirohi,andCharlesE.Tinney
4 Full-FieldStrainShapeEstimationfrom3DSLDV................................................................. 31
BryanWitt,DanRohe,andTylerSchoenherr
5 CharacterizationofaSmallElectro-MechanicalContactUsingLDVMeasurementTechniques.............. 47
KelseyM.Johnson
6 RemoteDetectionofAbnormalBehaviorinMechanicalSystems................................................. 59
GretaColford,EricaJacobson,KadenPlewe,EricFlynn,andAdamWachtor
7 Modal Analysis of a High-Speed Turbomachinery for Reliable Prediction of RD Properties
ThroughoutOperatingSpeedRange.................................................................................. 71
YuheiShindo,KazuhikoAdachi,SatoshiKawasaki,andMitsuruShimagaki
8 MappingMotion-MagnifiedVideostoOperatingDeflectionShapeVectorsUsingParticleFilters............ 75
AralSarrafiandZhuMao
9 StructuralHealthMonitoringofWindTurbinesUsingaDigitalImageCorrelationSystemonaUAV ...... 85
AshimKhadka,YaominDong,andJavadBaqersad
10 Full-FieldModeShapeIdentificationofVibratingStructuresfromCompressivelySampledVideo.......... 93
Bridget Martinez, Yongchao Yang, Ashlee Liao, Charles Farrar, Harshini Mukundan, Pulak Nath,
andDavidMascareñas
11 ExperimentalModalAnalysisofTumorigenesisandCancerMetastasis ......................................... 101
BridgetMartinez,YongchaoYang,CharlesFarrar,HarshiniMukundan,PulakNath,andDavidMascareñas
12 FullFieldStrainMeasurementsUsing3DLaserVibrometry...................................................... 105
SamuelTilmann
13 Output-Only Modal Parameter Estimation Using a Continuously Scanning Laser Doppler
VibrometerSystemwithApplicationtoStructuralDamageDetection ........................................... 113
Y.F.Xu,Da-MingChen,andW.D.Zhu
vii
Chapter 1
Detection of Sources of Nonlinearity in Multiple Bolted Joints
by Use of Laser Vibrometer
ArnaldodelliCarri,SanteCampanelli,andDarioDiMaio
Abstract The use of non-contact measurement methods for detecting and locating sources of nonlinearities can be
potentially a break-through in the nowadays experimental modal analysis. The primary goal is to define more effective
teststrategies,wherebycontactsensorswillmeasurethenonlinearvibrationresponsesatthebestlocationpossible.Jointed
structuresareatypicalexamplewherealargenumberofthejointcanposethequestionofwherewhatandhowtomeasure
the nonlinear response. Upon the identification of one, or more, nonlinear response mode the objective is to determine
whereisthesourceofsuchnonlinearvibration.Nonlinearitycanbecharacterisedwhenitssourceiswelldefinedandcanbe
adequatelytested.Thispaperwillattempttodetectandlocatethesourceofnonlinearityfromamulti-beamjointedassembly.
Theapproachwillbecarriedoutbyusingbothcontactandnon-contactmeasurementmethods,theresultsofwhichwillbe
comparedandevaluated.Theoperatortodetectthesourceofnonlinearitywillbethecoherencefunctionappliedtorandom
responsedata.
Keywords SLDV · Boltedjoints · Nonlinearvibrationtesting
1.1 Introduction
ThispaperattemptstoexploitthepotentialofthescanningLDVsystemtomeasurevibrationnonlinearresponseatamuch
greaternumberoflocations,thanitcanbedonebyusingsetupbasedoncontactsensors.Theobjectiveistousesuchdenser
measurementgrid to identify one, or more, sourcesof nonlinearity.It is not intendedto replace the accelerometerfor the
characterizationandquantificationofasourceofnonlinearity.Thelocalizationofnonlinearitiesisfundamentalwhensuch
sources are discrete as for bolted structures. It is notorious that structures with a high number of interfaces will exhibit
nonlinearresponseswhensubjectedtohighamplitudeofexcitationforces.Fromamodelvalidationviewpoint,theaccurate
localization, characterizationand quantificationof the nonlinearitycan make the modellingwork more effectiveand time
efficient.Resourcescanbededicatedtoimprovingthemodelwhereitisneededbyinclusionofthenonlinearphysics.
Thelocalizationofnonlinearitieswasusefullycarriedoutin[1].Itwasdemonstratedthatbysettingupagoodnumberof
accelerometersonastructurethelocalizationcanbedonewithagoodlevelofaccuracy.However,itlookedclearthatsuch
amethodoflocalizationdependsonthesetupofthecontactsensors,andwhenanengineeringjudgmentisnotbasedonthe
identificationofnonlinearityitmightbepossiblethatnonlinearitiesstayhiddentothesensors.Followingthemethodology
applied to locate the source of nonlinearity (explained in the following sections), it become interesting to use a different
technology which would enable much denser measurement grind than offered by contact sensors. Three research works
addressedthetopicoflocalizationbyusingthescanninglaservibrometer.Oneresearchwasfocussedonboltedflangesand
the use ofcontinuousscanningmethodstoidentifythe sourceof nonlinearity.Thatapproachshowedthatbymappingthe
responsephaseofthedeflectionshapemeasuredatconstantfrequencyandseverallevelofamplitudesonecoulddetermine
thelevelofnonlinearityexhibitedbyavibrationmode[2].Thescanninglaservibrometerwasusedinitsstep-scanningmode
intwoattempts,wherehighresolutionmodeshapesweremeasuredtodeterminewhichmodewouldexertmorenonlinear
A.delliCarri
SchoolofMechanical,AerospaceandAutomotiveEngineering,CoventryUniversity,Coventry,UK
S.Campanelli
DepartmentofMechanicalEngineering,Universita’PolitecnicadelleMarche,Ancona,Italy
D.DiMaio((cid:2))
DepartmentofMechanicalEngineering,UniversityofBristol,QueensBuilding,Bristol,UK
e-mail:[email protected]
©SocietyforExperimentalMechanics,Inc.2019 1
C.Niezreckietal.(eds.),RotatingMachinery,OpticalMethods&ScanningLDVMethods,Volume6,ConferenceProceedings
oftheSocietyforExperimentalMechanicsSeries,https://doi.org/10.1007/978-3-030-12935-4_1
2 A.delliCarrietal.
response[3].Theoutcomeofthatresearchshowedthatsomemodeshapescreatehighstraindistributionattheflanges’region
and thus enabling interface nonlinear conditions. A more recently publication was focussed on use the stepped scanning
methodto measurethe responsephase of the deflectionshapesof an aero-enginecasing assemblyonto whichaccessories
weremountedtogeneratesourcesofnonlinearities[4].Theresearchshowedthatresponsephaseofthedeflectionshapewas
agoodindicatorofthesourceofnonlinearity.
The present paper aims (i) at starting from those earlier success to detect the nonlinearities of a structure, and (ii) at
combiningthemethodoflocalizationbasedonaccelerometerswiththeuseofascanninglaservibrometer.Anovelstructure
willbeusedto explorethese newdevelopments.Thestructureismadeoften blockseachofwhichboltedbytwo boltsto
form a single prismatic beam. The source of nonlinearity can be moved by opening one or more pairs of bolts. The next
sectionwillexplaininmoredetailsthetestsstructureandsetup.Thepaperwillproceedbyattemptingthesamelocalization
methodusingasetoffourreferenceaccelerometersandthemeasurementmadebyascanninglaservibrometeroveragrid
of30points.
1.2 TestStructure, Setup andExperimental Method
Theteststructurewasdesignedwiththeideatorepeatthesamebasicunittentimes.Figure1.1showsthebasicunitwhich
canbeboltedbytwopairsofM8bolts.Figure1.2showsboththesolidmodeandtherealunitmadeofmildsteel.Thefull
assemblyofthetenunitsispresentedinFig.1.3.The18boltsweretightenedupto20Nmtoassurefullclampingconditions.
Thebeamwassuspendedbystringsfromaframeandashakerwasinstalledatthebottomoftheassembly,asshowedin
Fig. 1.4a.Thirtymeasurementpointswere markedon thebeam wherethe laser beamwouldmeasurethe vibrations.Four
referenceaccelerometerswerealsoincludedinthemeasurementsetup,oneofwhichatthedrivepointlocation.Figure1.4b
showsthemeasurementsetup.
Acustom-madecontrolLabViewpanelwasusedtodrivethelaserbeamontothemeasurementpointsandtoacquirethe
vibrationresponse. Itwas decidedto avoid the use the Polytec controlpanelto give full accessibility to the generationof
the excitation signal. Four randomnoise signals, with 1M samples at 10 kHz sampling frequency,were generatedat four
differentamplitudes.Thesefoursignalswerestoredandusedformeasuringthe30LDVmeasurementpointsandthefour
accelerometers.Thisapproachwasdecidedtoallowtheexcitationsignalfromthegeneratortobealwaysthesame,avoiding
Fig.1.1 CADdrawingofthebasicunit
1 DetectionofSourcesofNonlinearityinMultipleBoltedJointsbyUseofLaserVibrometer 3
Fig.1.2 Solidmodelin(a)andrealunitin(b)
Fig.1.3 Solidmodelin(a)andrealassemblyin(b)
variationsifitweretobegeneratedeverytime.Thefouramplitudeswereidentifiedasfollows,18mV,180mV,1080mV
and1800mV,respectively.Thegainoftheamplifierwasfixedatonelevelandneverchanged.
Thetestprogrammewasdesignedassuch.Thefirsttrialwasfocussedonassuringthecompletelinearityofthestructure
forthe20Nmtorqueappliedtothe18bolts.Hence,levels18mV,180mVand1800mVwereattempted.Thesecondtrial,
labelledasconfigurationA,wascarriedoutbyreducingthetorquefrom20Nm,to13Nmand8Nmofthepairofbolts,the
fifthfromthetop.Thethirdtrial,labelledconfigurationB,wascarriedoutusingthesametorquelevelsreducingthepairof
bolts,thethirdfromthetop,andbyresettingthefifthpairto20Nm.Atotalofthreeconfigurationweretried.
1.3 Theoretical Method
Theanalysiswasperformedusingconditionedspectraltechniquesfrom[5–8]andalreadyappliedinanearlierformin[1,
9].Thegeneralequationofmotionforan-DOFsnonlinearsystemis
(cid:2)M (cid:3) (cid:4) (cid:5)(cid:6)
Mx¨(t)+Cx˙(t)+Kx(t)+ q ·g w x(t),w x˙(t) =f(t)
i i i i
i=1
Where M, K, C are the n × n mass, stiffness and dampingmatrices, x(t) and its derivativesare the nx1 displacements,
velocitiesandaccelerationsvectors,f(t)isthenx1forcingvector.
In addition to the usual linear terms, there are M nonlinear (vectorial) terms that contribute to the system: under the
summation operatorone can discriminate the scaling factor q that quantifies the strength of the nonlinearitywith respect
i
