2013 nvh str_borne_workshop_web

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Presentation at 2013 SAE NVH Conference May 22, 2013
NVH Structure Borne NVH Workshop

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2013 nvh str_borne_workshop_web

  1. 1. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 1SAE 2013 NVH ConferenceStructure Borne NVH WorkshopAlan DuncanAlan Duncan Altair Engineering @ HondaNVH SpecialistGregGreg GoetchiusGoetchius Tesla MotorsNVH SpecialistJianminJianmin GuanGuan Altair EngineeringNVH ManagerContact Email: aeduncan@autoanalytics.com
  2. 2. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 2Structure Borne NVH WorkshopWorkshop Objectives -1. Review Basic Concepts of Automotive Structure Borne Noise.2. Propose Generic Targets.3. Present New Technology Example.Intended Audience –• New NVH Engineers.• “Acoustics” Engineers seeking new perspective.• “Seasoned Veterans” seeking to brush up skills.
  3. 3. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 3Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyUncertainty and NVH Scatter• Closing Remarks
  4. 4. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 4Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyUncertainty and NVH Scatter• Closing Remarks
  5. 5. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 5RideandHandlingNVH DurabilityImpactCrashWorthinessCompeting Vehicle Design Disciplines
  6. 6. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 6Automotive Engineering Objectives are Timeless
  7. 7. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 7Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyUncertainty and NVH Scatter• Closing RemarksAlan Duncan
  8. 8. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 8Structure Borne Noise and VibrationVibratingSourceFrequency Range: up to 1000 HzSystem Characterization• Source of Excitation• Transmission through Structural Paths• “Felt” as Vibration• “Heard” as Noise
  9. 9. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 9Structure Borne NoiseAirborne NoiseResponseLog Frequency“Low”Global Stiffness“Mid”Local Stiffness+Damping“High”Absorption+Mass+Sealing+Damping~ 150 Hz ~ 1000 Hz ~ 10,000 HzAutomotive NVH Frequency Range
  10. 10. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 10Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  11. 11. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 11Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  12. 12. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 12RECEIVERPATHSOURCEStructure Borne NVH Basics
  13. 13. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 13Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  14. 14. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 14mAPPLIED FORCEF = FO sin 2 π f tk c FTTR = FT / FTransmittedForceSingle Degree of Freedom Vibration= fraction of critical dampingfn = natural frequencyf = operating frequency( )2n22n22nff2)ff(1)ff(21ζζ+−+=ζmk
  15. 15. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 150 1 2 3 4 501234TransmissibilityRatio1.414Frequency Ratio (f / fn)Vibration Isolation PrinciplemAPPLIED FORCEF = FO sin 2 π f tk c FTTR = FT / FTransmittedForceIsolation RegionIsolation Region1.00.50.3750.250.150.1
  16. 16. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 16Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  17. 17. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 17Two Main SourcesNVH Source ConsiderationsSuspensionPowertrain
  18. 18. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 18Typical NVH Pathways to the PassengerPATHSFORSTRUCTUREBORNENVH
  19. 19. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 19Structure Borne NVH Sources
  20. 20. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 20Structure Borne NVH SourcesPrimary Consideration:Reduce the Source first as much aspossible because whatever enters thestructure is transmitted through multiplepaths to the receiver.Transmission through multiple paths ismore subject to variability.
  21. 21. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 21Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  22. 22. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 22Receiver ConsiderationsSubjective to Objective ConversionsSubjective NVH Ratings are typically based on a10 Point Scale resulting from Ride TestingA 2 ≈≈≈≈ 1/2 A 1Represents 1.0 Rating ChangeTACTILE: 50% reduction in motionSOUND : 6.dB reduction in sound pressure level( long standing rule of thumb )Receiver Sensitivity is a Key Consideration
  23. 23. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 23Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  24. 24. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 24Total 2178.2 Kg (4800LBS)Mass Sprung 1996.7 KgUnsprung 181.5 Kg (8.33% of Total)Powertrain 181.5 KgTires 350.3 N/mmKF 43.8 N/mmKR 63.1 N /mmBeam mass lumped ongrids like a beamM2,3,4 =2 * M1,5Symbolic Model of Unibody Passenger Car8 Degrees of FreedomFrom Reference 631826475
  25. 25. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 251 2 4 56 783TiresWheelsSuspensionSpringsEngine MassEngineIsolatorFlexible Beam for Body8 Degree of Freedom Vehicle NVH Model
  26. 26. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 268 Degree of Freedom Vehicle NVH ModelForce Applied to Powertrain AssemblyForces at Powertrain could represent a First OrderRotating ImbalanceFeng1 2 4 56 783
  27. 27. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 27Engine Isolation ExampleResponse at Mid Car0.00010.00100.01000.10001.00005.0 10.0 15.0 20.0Frequency HzVelocity(mm/sec)Constant Force Load; F ~ A 15.9 Hz8.5 Hz7.0 Hz700 Min. RPM First Order UnbalanceOperation Range of Interest318264753311882266447755
  28. 28. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 28Engine Isolation ExampleResponse at Mid Car0.00010.00100.01000.10001.00005.0 10.0 15.0 20.0Frequency HzVelocity(mm/sec)Constant Force Load; F ~ A700 Min. RPM First Order UnbalanceOperation Range of Interest31826475331188226644775515.9 Hz8.5 Hz7.0 HzEngine Idle SpeedOperating Shapesat 700 RPMLowest Body Movement
  29. 29. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 29Concepts for Increased Isolation“Double” isolation is the typical strategy forfurther improving isolation of a given vehicledesign.Subframe isIntermediate StructureSuspension Bushing is first levelSecond Level ofIsolation is at Subframeto Body Mount
  30. 30. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 308 Degree of Freedom Vehicle NVH ModelRemoved Double Isolation EffectWheelMassRemoved1 2 4 56 783
  31. 31. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 31Double Isolation ExampleVertical Response at DOF30.0E+001.0E+002.0E+003.0E+004.0E+005.0E+006.0E+005.0 10.0 15.0 20.0Frequency HzVelocity(mm/sec)Base ModelWithout Double_ISO1.414*fn318264753311882266447755
  32. 32. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 32Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  33. 33. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 33Mode Management Chart0 5 10 15 20 25 30 35 40 45 50HzFirst Order Wheel/Tire Unbalance V8 IdleHot - ColdEXCITATION SOURCESInherent Excitations (General Road Spectrum, Reciprocating Unbalance, Gas Torque, etc.)Process Variation Excitations (Engine, Driveline, Accessory, Wheel/Tire Unbalances)HzHz0 5 10 15 20 25 30 35 40 45 500 5 10 15 20 25 30 35 40 45 50CHASSIS/POWERTRAIN MODESRide ModesPowertrain ModesSuspension Hop and Tramp ModesSuspension Longitudinal ModesExhaust ModesBODY/ACOUSTIC MODESBody First Bending First Acoustic ModeSteering Column First Vertical BendingBody First Torsion(See Ref. 1)
  34. 34. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 348 Degree of Freedom Vehicle NVH ModelBending Mode Frequency SeparationBeam Stiffness wasadjusted to align BendingFrequency with SuspensionModes and thenprogressively separatedback to Baseline.1 2 4 56 783
  35. 35. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 35Response at Mid Car0.101.0010.00100.005 10 15 20Frequency HzVelocity(mm/sec)18.2 Hz Bending13.Hz Bending10.6 Bending8 DOF Mode Separation Example18.2 Hz13.0 Hz10.6 Hz318264753311882266447755
  36. 36. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 36Response at Mid Car0.101.0010.00100.005 10 15 20Frequency HzVelocity(mm/sec)18.2 Hz Bending13.Hz Bending10.6 Bending8 DOF Mode Separation ExampleAll OperatingShapes at 10.6 Hz318264753311882266447755 Highest Body Bending
  37. 37. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 37Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  38. 38. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 38Front input forces Rear input forcesFirst Bending: Nodal Point Mounting ExampleMount at Nodal PointLocate wheel centers at node points of the first bending modeshapeto prevent excitation coming from suspension input motion.
  39. 39. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 39Passenger sits atnode point forFirst Torsion.Side ViewFirst Torsion: Nodal Point Mounting ExamplesMount at Nodal PointTransmission Mount of a3 Mount N-S P/T is nearthe Torsion Node.Rear ViewEngine
  40. 40. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 40Powertrain Bending Mode Nodal MountingMount system is placed to support Powertrain at the Nodal Locations ofthe First order Bending Mode.Best compromise with Plan View nodes should also be considered.1 2 4 56 73
  41. 41. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 411 2 4 56 7838 Degree of Freedom Vehicle NVH ModelBending Node Alignment with Wheel CentersRedistribute Beam Massesto move Node Points toAlign with points 2 and 4
  42. 42. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 42Response at Mid-Car0.0E+001.0E+002.0E+003.0E+004.0E+005.0 10.0 15.0 20.0Frequency HzVelocity(mm/sec)Node ShiftedBase ModelFirst Bending Nodal Point Alignment318264753311882266447755
  43. 43. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 43Response at Mid-Car0.0E+001.0E+002.0E+003.0E+004.0E+005.0 10.0 15.0 20.0Frequency HzVelocity(mm/sec)Node ShiftedBase ModelFirst Bending Nodal Point Alignment318264753311882266447755OperatingShapes at18.2 HzNode Shifted ModelNo Residual Body Bending
  44. 44. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 44Diagnosis: Increase at 10.2 HzBody Bends up at Downward Position of Cycle
  45. 45. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 45Diagnosis: Increase at 10.2 HzMotion Experienced whenBending is PresentMotion Experienced whenBending is RemovedDiagnosis: Increase at 10.2 HzCenter - Undeformed PositionUp PositionDown PositionCONCLUSION:Response Increases when aBeneficial mode is Removed.
  46. 46. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 46Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  47. 47. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 47YOxSDOFDynamic Absorber ConceptMYOxAuxiliary Spring-Mass-Damperm = M / 102DOFM
  48. 48. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 48Powertrain Example of Dynamic AbsorberAnti-Node Identifiedat end of Powerplantk cAbsorber attached at anti-node acting inthe Vertical and Lateral plane.Tuning Frequency = √√√√ k/mm[Figure Courtesy of DaimlerChrysler Corporation]
  49. 49. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 49Baseline Sound Level63 Hz Dynamic Absorber63 + 110 Hz AbsorbersBaseline Sound Level63 Hz Dynamic Absorber63 + 110 Hz Absorbers[Figure Courtesy of DaimlerChrysler Corporation]10dB
  50. 50. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 50Low Frequency Basics - Review• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation StrategiesProvide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
  51. 51. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 51Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyUncertainty and NVH Scatter• Closing RemarksJianmin Guan
  52. 52. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 52Mid Frequency NVH FundamentalsThis looks familiar!Frequency Range of Interest has changed to150 Hz to 1000 Hz
  53. 53. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 53Typical NVH Pathways to the PassengerPATHSFORSTRUCTUREBORNENVHNoise Paths are thesame as LowFrequency RegionNoise Paths are thesame as LowFrequency Region
  54. 54. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 54Mid-Frequency Analysis CharacterStructure Borne NoiseAirborne NoiseResponseLog Frequency“Low”Global Stiffness“Mid”Local Stiffness+Damping“High”Absorption+Mass+Sealing~ 150 Hz ~ 1000 Hz ~ 10,000 HzHigh modal densityand coupling insource, path andreceiver• Mode separation is less practical inmid-frequency• New Strategy is Effective Isolation:Achieved by reducing energy transferlocally between source and receiver atkey paths.•• Mode separation is less practical inMode separation is less practical inmidmid--frequencyfrequency•• New Strategy is Effective Isolation:New Strategy is Effective Isolation:Achieved by reducing energy transferAchieved by reducing energy transferlocally between source and receiver atlocally between source and receiver atkey paths.key paths.
  55. 55. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 55Mid-Frequency Analysis CharacterControl Measures for Mid Frequency ConcernsEffective IsolationAttenuation along Key Noise Paths
  56. 56. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 56Mid-Frequency Analysis CharacterControl Measures for Mid Frequency ConcernsEffective IsolationAttenuation along Key Noise Paths
  57. 57. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 57Classical SDOF: RigidSource and ReceiverTransmissibilityRatio1.0 1.414 10.0f / f n“Real Structure”Flexible (Mobile)Source andReceiverIsolation EffectivenessEffectiveness deviates from the classical development as resonancesoccur in the receiver structure and in the foundation of the source.Isolation RegionIsolation Region1.0
  58. 58. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 58Mobility• Mobility is the ratio of velocity response at the excitation point on structurewhere point force is appliedMobility =VelocityForce• Mobility, related to Admittance, characterizes Dynamic Stiffness ofthe structure at load application pointMobility =Frequency * DisplacementForce=FrequencyDynamic Stiffness
  59. 59. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 59• The isolation effectiveness can be quantified by a theoretical model based onanalysis of mobilities of receiver, isolator and source• Transmissibility ratio is used to objectively define measure of isolationTR =Force from source without isolatorForce from source with isolatorIsolationV rV irV isF rF irReceiverSourceF isFsV sIsolatorVF s=Y i + Y r + Y sV rF rReceiverSourceF sV sVF s=Y r + Y sVV
  60. 60. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 60TR =  ( Y r + Y s ) //// ( Y i + Y r + Y s ) • For Effective Isolation (Low TR) the IsolatorMobility must exceed the sum of the Source andReceiver Mobilities.Y r : Receiver mobilityY s : Source mobilityY i : Isolator mobilityV mV imV ifF mF imReceiverSourceF ifF fV fIsolatorTR =Force from source without an isolatorForce from source with an isolatorIsolationRecall thatK1Y ∝
  61. 61. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 61TR =  ( ) //// ( ) K body1K source1+K body1+K iso1K source1+K isoK sourceK bodyK iso1.0 5.0 20.01.05.020.00.67 0.55 0.510.55 0.29 0.200.51 0.20 0.09Generic targets:body to bushing stiffness ratio of at least 5.0source to bushing stiffness ratio of at least 20.0Designing Noise Paths
  62. 62. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 62Body-to-Bushing Stiffness RatioRelationship to TransmissibilityStiffness Ratio; K body / K isoTransmissibilityRatioTR00.10.20.30.40.50.61 2 3 4 5 6 7 8 9 10Target Min. = 5gives TR = .20For a source ratio of 20
  63. 63. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 63Mid-Frequency Analysis CharacterControl Measures for Mid Frequency ConcernsEffective IsolationAttenuation along Key Noise Paths
  64. 64. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 64Identifying Key NVH PathsKey NVH paths are identified by Transfer Path Analysis (TPA)FiTactileTransferTactileTransferAcousticTransferAcousticTransferOperating loads Operating loadsBreak the system at thepoints where the forcesenter the body (Receiver)Total Acoustic Response is summation of partial responsesover all noise pathsPt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ (P/F) i * Fi ]
  65. 65. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 65Identifying Key NVH PathsTPA Example: Contribution at One Transfer PathPartial response from a particular path: Pi = (P/F) i * FiP/T LoadCrank torque91 HzFiTFi
  66. 66. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 66Identifying Key NVH PathsTPA Example: Sum of Key Transfer Paths at One PeakP/T LoadCrank torqueP/T LoadCrank torqueTotal Response: Pt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ (P/F) i * Fi ]
  67. 67. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 67Attenuating Key NVH PathsTPA Example: Identifying Root Cause of Dominant PathsP/T LoadCrank torquePMiFiTFi
  68. 68. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 68Attenuating Key NVH PathsTPA Example: Dominant Paths over FrequenciesP/T LoadCrank torqueFiTFiPMi
  69. 69. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 69Designing Noise PathsTPA Example: Cascading Vehicle Targets to SubsystemsLimit TF to a 55 dB targetSee changes in responseP/T LoadCrank torqueTFiOnce the dominant noise paths androot cause have been identified, thetask is reduced to solving problems of:1. High Force2. High Transfer Function3. High Point Mobility
  70. 70. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 70Designing Noise PathsFiAcoustic Transfer (P/F)iAcoustic Transfer (P/F)iOperating loads createForces (Fi) into body atAll noise pathsF FF FFF FPt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ Fi * (P/F) i ]= ΣΣΣΣ paths [ Fi * (P/V) i * (V/F)i]P/VP/F(Kbody)V/FMeasurement Parameters Generic TargetsP/F Acoustic Sensitivity 50 - 60 dBL/NV/F Structural Point Mobility(Receiver Side)0.2 to 0.3mm/sec/N
  71. 71. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 71Recall for Acoustic Response PtPt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ Fi * (P/V) i * (V/F)i]“Downstream” Effects: Body Panels(P/V)i !!!! “Downstream” (Body Panel) System Dynamics: Three Main Effects:Increased DampingIncreased Stiffness1. Panel Damping2. Panel Stiffness3. Panel Acoustic Contribution
  72. 72. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 72Generic Noise Path TargetsK isoK body> 5.0K isoK source> 20.0AcousticSensitivity<50 - 60dBL/NStructuralMobility < 0.2 to 0.3 mm/sec/NPanel Damping Loss Factor> .10Primary: Minimize the Source Force< 1.0 N
  73. 73. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 73Final Remarks on Mid Frequency Analysis• Effective isolation at dominant noise paths is critical• Effective isolation at dominant noise paths is critical• Reduced mobilities at body & source and softenedbushing are key for effective isolation• Reduced mobilities at body & source and softenedbushing are key for effective isolation• Other means of dealing with high levels of response(Tuned dampers, damping treatments, isolatorplacement at nodal locations) are also effective• Other means of dealing with high levels of response(Tuned dampers, damping treatments, isolatorplacement at nodal locations) are also effective• Mode Separation remains a valid strategy as modesin the source structure start to participate• Mode Separation remains a valid strategy as modesin the source structure start to participate
  74. 74. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 74Structure Borne NVH: Concepts Summary• Source-Path-Receiver as a system1. Reduce Source2. Rank and Manage Paths3. Consider Subjective Response• Effective Isolation• Mode Management• Nodal Point Placement• Attachment Stiffness• “Downstream” (Body Panel) Considerations• Source-Path-Receiver as a system1. Reduce Source2. Rank and Manage Paths3. Consider Subjective Response• Effective Isolation• Mode Management• Nodal Point Placement• Attachment Stiffness• “Downstream” (Body Panel) Considerations
  75. 75. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 75Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyUncertainty and NVH Scatter• Closing RemarksGreg Goetchius
  76. 76. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanToolbox Demo Noise Test Results85616863554739304050607080901) Baseline:Imbalance, NoIsolation2) Imbalance +Isolation3) No Imbalance,No Isolation4) No Imbalance,No Isolation +Damping5) No Imbalance +Isolation +Damping6) #5 + Absorption 7) #6 + InsulatorMatSPL(dBA)Tool Box Demo Test Results
  77. 77. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 77Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyNVH Scatter and UncertaintyClosing Remarks Alan Duncan
  78. 78. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 78NVH Scatter and Uncertainty• Scatter 20 Years Ago• Scatter 10 Years Ago• New Technology to Address Scatter
  79. 79. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 79NVH Scatter and Uncertainty• Scatter 20 Years Ago• Scatter 10 Years Ago• New Technology to Address Scatter
  80. 80. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 80Frequency ( Hz )Mag.ofFRFMagnitude of 99 Structure Borne Noise Transfer Functions forRodeo’s at the Driver MicrophoneMeasurements from Kompella and Bernhard( Ref. 8 ) 1993 Society of Automotive Engineers, Inc.
  81. 81. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 81SoundPressure[dB(lin)]Frequency ( Hz )Acoustic Scatter from Simulation of thevibroacoustic behavior of a vehicle dueto possible tolerances in the componentarea and in the production process.© 2000 Society of Automotive Engineers, Inc.Reproduced with permission from paperby Freymann, et. Al. (Ref. 9)12 dB VariationExperimentally detected Scatter in lowfrequency vibroacoustic behavior ofproduction vehicles.Freymann, BMW NVH Scatter Results
  82. 82. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 82CONCLUSIONs: From K/B and BMW StudiesIt is not highly probable:1. that a Single Test will represent the Mean response2. that a CAE Simulation will match a Single TestVariability observed from multiple tests of “identical” vehicles isimportant in understanding the degree to which the Test (orSimulation) of a Design is representative of the Mean response.How many Tests (or Simulations) of a Design would be requiredfor the result to be considered statistically significant?Scatter Implications for Test (or Simulation) NVH DevelopmentScatter is the “Physics”Test Simulation
  83. 83. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 83NVH Scatter and Uncertainty• Scatter 20 Years Ago• Scatter 10 Years Ago• New Technology to Address Scatter
  84. 84. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 84Test Variation Band10. dB; 50-150 Hz20. dB; 150-500 HzReference Baseline Confidence CriterionFor Operating Response SimulationsTest Upper BoundTest Band AverageTest Lower BoundREF. 8Confidence Criterion:Simulation result mustfall within the band oftest variation.Simulation PredictionFUDGEFACTORSSoundFRFFrequency Hz2003 Workshop Confidence Criterion Lecture with Voice Trackavailable at www.AutoAnalytics.com on DOWNLOAD page.
  85. 85. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 85FlashBack: 1995 Paper on Root Cause of Scatter(Ref. 15)
  86. 86. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 86Root Cause of Scatter : ConditionsTotal Response
  87. 87. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 87NVH Scatter and Uncertainty• Scatter 20 Years Ago• Scatter 10 Years Ago• New Technology to Address Scatter
  88. 88. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 88(Ref. 12)Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniGoal: Define a Modeling Methodology that:1. Accounts for NVH Scatter2. Quantifies Uncertainty with StatisticalSignificance using a Stochastic Model3. Accounts for the Combined Effect of Modelingand Manufacturing Uncertainty
  89. 89. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 89(See Ref. 11 for Model Details)Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniTactile ResponsesPOWERTRAIN LOADSNTF @ DRIVER EAR
  90. 90. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 90Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniStandard Eqn. forStructural-AcousticCoupling Modal ModelTypical Derivation forcreating the randomizedDynamic Matrix withGaussian Distribution.Non-Parametric: DirectChanges in Modal Matrices.The scatter created is afunction of:Dispersion Parameter: δOnce determined, δ is aconstant controlling theamplitude level of scatter.7 Dispersion Constantsare needed:3 for Structure: M, D, K3 for Acoustics: M, D, K1 for Coupling: Cn,m
  91. 91. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 91Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniProof of Process ConvergenceCONCLUSIONS: Converged at 200 REALIZATIONSand with Struct to 400 and Fluid to 350 HzMonte CarloRandomizationConverges at 200Realizations of theRandom Matrices.Increasing No. ofModes
  92. 92. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 92Structural UncertaintyCouplingUncertaintyAcoustic Uncertainty95% Upper Confidence BandNominal / Original Model Response50% Confidence Band (Mean Stochastic Model)95% Lower Confidence BandNon-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniCONCLUSION:• The Model shows 95%Confidence Bands withincreasing Scatter at higherfrequency similar to K-B Study.
  93. 93. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 93(Ref. 13)Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniMain Paper - Development is ExtensiveIncludes Test Data Comparison
  94. 94. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 94FIG. 10. Finite element mesh of the computational structural acoustic model.(See Ref. 11 for Model Details)Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniFull Vehicle System – Body and ChassisStructural-Acoustic ModelSimilar Detail Level as first paper
  95. 95. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 95FIG. 16. Comparisons of the stochastic computational model results with the experiments. Graphs of the rootmean square of the acoustic pressures averaged in the cavity in dB scale: experiments for the 30 configurations(gray lines); Mean computational model (dashed line); mean value of the random response (mid thin solid line);95% confidence region: the upper and lower envelopes are the upper and lower thick solid lines.Non-Parametric Probabilistic Simulation; Soize, Durand, Gagliardini95% UPRNominal50% Mean95% LWRNOTE: Acoustic Dispersion Parameters are determined here with Mean Structure held Invariant.
  96. 96. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 96FIG. 19. Comparisons of the stochastic computational model results with the experiments for observationObs6. Graphs of the moduli of the FRFs in dB scale: experiments for the 20 cars (gray lines); Meancomputational model (dashed line); mean value of the random response (mid thin solid line); confidenceregion: the upper and lower envelopes are the upper and lower thick solid lines.OBS # 6Non-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniP/T Load2nd Order95% UPRNominal50% Mean95% LWRNOTE: Structure Dispersion Parameters are determined here with Mean Acoustic held Invariant.
  97. 97. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 97FIG. 20. Comparisons of the stochastic computational model results with the experiments for the boomingnoise. Graphs of the moduli of the FRFs in dB(A) scale: experiments for the 20 cars (thin gray lines); meanvalue of the experiments (thick gray line); Mean computational model (dashed line); Mean value of therandom response (mid thin solid line); 95% confidence region: the upper and lower envelopes are the upperand lower thick solid lines.P/T Load2nd Order95% UprNominal50% Mean95% LwrNon-Parametric Probabilistic Simulation; Soize, Durand, Gagliardini
  98. 98. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 98FIG. 20. Comparisons of the stochastic computational model results with the experiments for the boomingnoise. Graphs of the moduli of the FRFs in dB(A) scale: experiments for the 20 cars (thin gray lines); meanvalue of the experiments (thick gray line); Mean computational model (dashed line); Mean value of therandom response (mid thin solid line); 95% confidence region: the upper and lower envelopes are the upperand lower thick solid lines.P/T Load2nd Order95% UprNominal50% Mean95% LwrNon-Parametric Probabilistic Simulation; Soize, Durand, GagliardiniCONCLUSIONS:. The 95% Confidence Bands encapsulate the Measured Scatter of 20 Vehicles.. Half-Bandwidth Scatter (between Mean and Upr 95%) is similar to K-B Half-Bands.NOTE: The Method has Quantified the Model and Manufacturing Combined Uncertainty.
  99. 99. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 99(Ref. 14)Non-Parametric Probabilistic Simulation; Jund, Guillaume, Gagliardini
  100. 100. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 100FIG. 4: Computed booming noise inside a car vs. rpm, using only structure-borne excitation compared with themeasured value (brown bold). Thin dotted black: deterministic computation; green: median value; thin dottedblue: lower bound with a 95% probability; dotted red: upper bound with a 95% probability.P/T Load2nd OrderNon-Parametric Probabilistic Simulation; Jund, Guillaume, Gagliardini95% UprNominal50% Mean95% LwrTestMeasurementAuthor:Focus of Correlation EffortAll Test Peaks in Band: Results imply aCountermeasure is needed.
  101. 101. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 101FIG. 7: Booming noise inside a car vs rpm.Stochastic modelling. Comparison of the medianvalue of a baseline configuration (green) with amodification set (blue bold)P/T Load2nd OrderNon-Parametric Probabilistic Simulation; Jund, Guillaume, GagliardiniFIG. 6: Booming noise inside a car vs rpm.Deterministic models. Comparison of a baselineconfiguration (green) with a modification set (bluebold).DETERMISTIC MODEL STOCHASTIC MODEL - Mean Level. Amplitude Range = 30 dB. Need Tradeoff Judgment. Amplitude Range = 15 dB. Decision is Clearer thatboth Designs are EqualPerformersBlue: New DesignGreen: BaseA-B Design Decision using Deterministic Model - vs - Mean Stochastic Model
  102. 102. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 102Conclusions:Kompella and Bernhard Test Observations are still relevant after 20 Years.Scatter-like NVH Variation exists even in Best-in-Class vehicles.Observations about Scatter:Observations from Soize, Durand, Gagliardini, et. al. PapersThe Non-Parametric stochastic computational model with dispersionparameters derived from a test database accounts for NVH Scatter dueto combined Modeling and Manufacturing Uncertainties.The Upper, Lower, and Mean Confidence Probabilities lead to moreprecise assessment of the effects of NVH scatter.A database of dispersion parameters enables a virtual productdevelopment process assuring robust NVH performance.The model configuration lends itself to an automated computationalmethodology driving a robust virtual product development process.
  103. 103. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 103Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• New TechnologyUncertainty and NVH Scatter• Closing Remarks: Q & AAlan-Greg-Jimi
  104. 104. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 104SAE 2013 NVH ConferenceStructure Borne NVH WorkshopThank You for Your Time!Q & AQ & A
  105. 105. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 105Primary References (Workshop Basis: 4 Papers)1. A. E. Duncan, et. al., “Understanding NVH Basics”, IBEC, 19962. A. E. Duncan, et. al., “MSC/NVH_Manager Helps Chrysler MakeQuieter Vibration-free Vehicles”, Chrysler PR Article, March 1998.3. B. Dong, et. al., “Process to Achieve NVH Goals: SubsystemTargets via ‘Digital Prototype’ Simulations”, SAE 1999-01-1692,NVH Conference Proceedings, May 1999.4. S. D. Gogate, et. al., “’Digital Prototype’ Simulations to AchieveVehicle Level NVH Targets in the Presence of Uncertainties’”,SAE 2001-01-1529, NVH Conference Proceedings, May 2001Structure Borne NVH ReferencesWS + Refs. at www.AutoAnalytics.com at download linkStructure Borne NVH Workshop - on InternetAt SAE www.sae.org/events/nvc/specialevents.htm
  106. 106. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 106Supplemental Reference Recommendations5. T.D. Gillespie, Fundamentals of Vehicle Dynamics, SAE 1992(Also see SAE Video Lectures Series, same topic and author)6. D. E. Cole, Elementary Vehicle Dynamics, Dept. of MechanicalEngineering, University of Michigan, Ann Arbor, Michigan, Sept.19727. J. Y. Wong, Theory of Ground Vehicles, John Wiley & Sons, NewYork, 19788. N. Takata, et.al. (1986), “An Analysis of Ride Harshness” Int.Journal of Vehicle Design, Special Issue on Vehicle Safety, pp.291-303.9. T. Ushijima, et.al. “Objective Harshness Evaluation” SAE PaperNo. 951374, (1995).10. G. Goetchius; “The Seven Immutable Laws of CAE/TestCorrelation” Sound and Vibration Mag. Editorial June 2007, onlineat SandV.comStructure Borne NVH References
  107. 107. 2013 SAE NVC Structure Borne Noise Workshop2013 Automotive Analytics LLC A.E.DuncanSlide 107New Technology References (2013 NVH Workshop)11. Sol, A.; Van Herpe, F.; “Numerical Prediction of a Whole Car Vibro-AcousticBehavior at Low Frequencies”; SAE # 2001-01-152112. Durand, J.; Gagliardini, L.; Soize, C.; “Nonparametric Modeling of theVariability of Vehicle Vibroacoustic Behavior”; SAE # 2005-01-2385; SAE 2005Noise and Vibration Conference Proceedings.13. Durand, J.; Gagliardini, L.; Soize, C.; “Structural-acoustic modeling ofautomotive vehicles in presence of uncertainties and experimental identificationand validation”; Journal of the Acoustical Society of America 24, p 1513-152514. Jund, A.; Gagliardini, L.; et.al.; “AN INDUSTRIAL IMPLEMENTATION OFNON-PARAMETRIC STOCHASTIC MODELLING OF VEHICLEVIBROACOUSTIC RESPONSE” CONVEBONOV Workshop, University ofSussex, Brighton, UK, March 27-28 201215. Gardhagen, B. and Plunt, J., “Variation of Vehicle NVH Properties due toComponent Eigenfrequency Shifting - Basic Limits of Predictability” SAE 951302May 1995 NVH ConferenceStructure Borne NVH References

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