《PAKTPASeminarsmall.ppt》由会员分享，可在线阅读，更多相关《PAKTPASeminarsmall.ppt（33页珍藏版）》请在三一办公上搜索。
1、PAK TPA methods,Software modules,Background information,Application examples,X,=,Introduction,With transfer path analysis the relation between the source(s),the transfer and the receiver is analysed.,Structure-Structure,Acoustic StructureStructure-Acoustic,Acoustic-Acoustic,AccelerationStrainForceSo
2、und PressureHydro Pressureetc.,CombustionWindWheel/RoadRotating partsHydro pulsationetc.,Excitation,measurable Source sided response,Transfer,Receiver sided response,PAK transfer path analysisOverviewTPA methodsModulesWorkflowsBackground of CrossTalk Cancellation(CTC)and Operational TPATheoryBenefit
3、sLimitationsTPA resultsSensor placementApplication examples,schematical,Content,Time domain TPS network,Transfer Path Synthesis,Graphics/analysis:FFT/APSorders.,Crosstalk Cancellation(CTC+AMM):Determination of transfer functionssave as PAK-measurement,TPS network:calculates contributions receiver,Op
4、erational TPA,Operational measurement:WOTpartial loadrun-down,Operational measurement:WOTpartial loadrun-down,Graphics/analysis:FFT/APSorders.,Artificial excitation measurement:impactshakerspeaker.,TPS network:calculates contributions receiver,Impact TPA-Crosstalk compensated,CTC(without AMM),no com
5、pensation of crosstalkFRFs are taken directly from measurement,Operational measurement:WOTpartial loadrun-down,Graphics/analysis:FFT/APSorders.,Artificial excitation measurement:impactshakerspeakermount stiffnesses.,TPS network:calculates contributions receiver,Impact TPA-Crosstalk not compensated,P
6、AK transfer path analysisOverviewTPA methodsModulesWorkflowsBackground of CrossTalk Cancellation(CTC)and Operational TPATheoryBenefitsLimitationsTPA resultsSensor placementApplication examples,schematical,Content,Transfer functions(for Y=X.H):Hi=Xt,i-1*Yt,t:observationi:channelX-1:Pseudo-Inverse,out
7、putYt,inputXt,i,Principle,Hz,y1y2y3yn,x11 x1mx21 x2mx31 x3mxn1 xnm,Simultaneously measured data,Acceleration,sound pressure,m references,1 response,n observations(over time,rpm,impact,),H1Hm,=,*,-1,Y=X*H,H=X-1*Y,(Operational)transfer characteristics,Matrix conditioning:overdeterminationvaried excita
8、tion(WOT,partial,rundown,.),Principle,How can we calculate the pseudo inverse of X?The singular value decomposition(SVD)identifies linear independant deflection shapes.Any actual observation can then be described as a linear combination of these shapes.The decomposition into deflection shapes makes
9、the calculation of the pseudo inverse easy.,SVD:when X=U S V+(where U and V are unitary matrices and S diagonal with decreasing singular values)then X-1=V S-1 U+,Pseudo inverse,Comparable to an Eigenvalue decomposition the measured data are separated into singular values.This decomposition is a tran
10、sformation into a space of linear independent(orthogonal)principal components.,1st principal component=largest singular value,2nd principal component=next singular value,single FFT result,Principal Component Analysis(PCA)Singular Value Decomposition(SVD),Lets call the 1st PC bending and the 2nd PC t
11、orsion.Each measurement point can then be described by a certain amount of bending and an amount of torsion.,ch1,ch2,rotated coordinate system,As a least squares approach the SVD searches for the best set of singular values to get the best fit of the measured data noise included.Noise components are
12、 eliminated and not part of the inversion.,Principal Component Analysis(PCA)Singular Value Decomposition(SVD),x1,x2,x3,xn,t1,t2,t3,tn,50%,20%,10%,1%,yj,Reference,PrincipalComponents,Response,Singular Values(cumulated),Principal Components,Accelerations,Sound Pressure,Eliminate noise components,Refer
13、ence:“Method of Transfer Path Analysis for Vehicle Interior Sound with no Excitation Experiment”Kousuke Noumura,Junji Yoshida,Honda R&D Co.,Ltd.,Japan,H=X-1 Y,Benefits:Crosstalk is automatically included since only reactions to any kind of excitation are measured(source side and receiver side)Correc
14、t separation of airborne and structure borne componentsNo artificial excitation is needed(typical problems like a bad coherence due to a vibrating plate nearby the hammer do not occur)Fast resultsThe operating state is described rather than the idle structure(the result is not distorted by wrong tem
15、peratures,.)Correct positioning of sensors is not as crucial as for impact TPA,Operational TPA,Limitations:All coherent transmission paths need to be measured simultaneouslyto separated them correctly.No information about forcesThe quality depends on the energy to noise ratio good results are obtain
16、ed for example-up to 2 kHz for an engine TPA to the drivers ear-up to 5 kHz at an engine test benchSmall contributions are less accurate.The OTPA works best for identifying the main contributions.Sensor placement and interpretation of results needs engineering knowledge.,Operational TPA,PAK transfer
17、 path analysisOverviewTPA methodsModulesWorkflowsBackground of CrossTalk Cancellation(CTC)and Operational TPATheoryBenefitsLimitationsTPA results demonstrated in PAK softwareSensor placementApplication examples,schematical,Content,PAK transfer path analysisOverviewTPA methodsModulesWorkflowsBackgrou
18、nd of CrossTalk Cancellation(CTC)and Operational TPATheoryBenefitsLimitationsTPA resultsSensor placementApplication examples,schematical,Content,Sensor placementAll measured signals are responses to existing physical excitationsOne sensors measures typically a superposition of reactions to different
19、 sources depending on the“distance”to the source.If a source is not detected by any sensor then its contribution cannot be reproduced(e.g.wind).Its possible to place more than one sensor to capture one contribution(e.g.mics in engine compartment).The total contribution is the sum of the single contr
20、ibutions.The combustion for example is the source for structure borne engine paths as well as for airborne sound.At some points like a carbody connection for example several sources are superposed.The analysis will thus give a contribution analysis of these points rather than an information about th
21、e original sources.Different hierarchical interface levels must not be mixed.,Overview,Source contributionThe sources can be separated because the sensors are placed close by the sources.,Sensor placement,Path contributionHere the contributions from the positions where the sensors are placed can be
22、regarded as path contributions.cs=cp,i,cs,cs,cs,cp,cp,cp,cp,cp,cp,cp,cp,A missing pathHere the source contribution is distributed to the measured paths.The paths contributions are different from the regular case but their sum is still cs.,Sensor placement,Mixed TPA levelsThe sum equals the contribut
23、ion of the source.The single cs cannot be interpreted correctly.,cp,cp,cp,cp,cp,cp,cp,cp,cp,cp,cp,cp,cs,cs,Sensor placementincoherent sources which are not captured by any sensor,Without the wheel sensors the road excitation can NOT be reproduced.(Incoherent source),Sensor placementsame source coher
24、ent path contributions,Without the gearbox sensor the egine contribution CAN be reproduced.It is fully captured by the remaining egine mount sensors.(Coherent contributions),measured with 2 gearbox sensors,The summed contribution of the two sensors is the same as the contribution when measured with
25、only one sensor.,Sensor placementmultiple sensors can be used for a(sub-)system,PAK transfer path analysisOverviewTPA methodsModulesWorkflowsBackground of CrossTalk Cancellation(CTC)and Operational TPATheoryBenefitsLimitationsTPA resultsSensor placementApplication examples,schematical,Content,Driver
26、s ear Scenario 1,Interface-/Source-points:Engine points(SB+AB),Target:Drivers ear,SB:Structure borneAB:Airborne,Interface-/Source-points:Cabin(SB+AB),Drivers ear Scenario 2(a),Target:Drivers ear,Drivers ear Scenario 2(b),Interface-/Source-points:Engine(SB only),Target:dominant source from 2(a),Local
27、 TPA,Interface-/Source-points:Cabin attachment(SB only),Target:Steering wheelDrivers seat,Steering wheel vibration Scenario 3,Steering wheel vibration Scenario 4,Interface-/Source-points:Engine(SB only),Target:Steering wheelDrivers seat,Road noise,Interface-/Source-points:Wheels,(SB+AB),close to exc
28、itation,Target:Drivers ear,Road noise,Interface-/Source-points:Wheel attachments(SB)Sound pressure(AB),Accelerometers behind the mount(carbody-side),Target:Drivers ear,Summary:The application scenario defines the position of the sensorsWhich are possible paths or interface points?“these are the sens
29、or positions.Whats the logical distance between the sensors(see figure)?Are two neighboured sensors expected to measure almost the same signal or not?Sensor placement and interpretation of results needs engineering knowledge.Then OTPA is a very fast and efficient contribution analysis.,Operational TPA,Source,Source,or,?,Thank youPlease dont hesitate to contact me should I be able to assist you with anything,2/5/2023,
