2011 SAE Structure Borne NVH Workshop Web

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Slides from SAE Structure Borne NVH Workshop presented in Grand Rapids, Michigan

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2011 SAE Structure Borne NVH Workshop Web

  1. 1. SAE 2011 NVH Conference Structure Borne NVH Workshop Presenters: Alan Duncan Altair Engineering @ Honda Contact Email: aeduncan@autoanalytics.com Web: www.autoanalytics.com Greg Goetchius Tesla Motors Kiran Govindswamy FEV Inc. Jianmin Guan Altair Engineering Slide 12011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  2. 2. Structure Borne NVH Workshop Workshop Objectives - 1. Review Basic Concepts of Automotive Structure Borne Noise. 2. Propose Generic Targets. 3. Present Real World Application Example. Intended Audience – • New NVH Engineers. • “Acoustics” Engineers seeking new perspective. • “Seasoned Veterans” seeking to brush up skills. Slide 22011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  3. 3. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Slide 32011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  4. 4. Structure Borne NVH Workshop • Introduction Greg Goetchius • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Slide 42011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  5. 5. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Slide 52011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  6. 6. Competing Vehicle Design Disciplines Ride Impact and CrashWorthiness Handling NVH Durability Slide 62011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  7. 7. Structure Borne Noise and Vibration Vibrating Source Frequency Range: up to 1000 Hz System Characterization • Source of Excitation • Transmission through Structural Paths • “Felt” as Vibration • “Heard” as Noise Slide 72011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  8. 8. Automotive NVH Frequency Range Structure Borne Noise Airborne NoiseResponse Absorption + Mass + Local Stiffness Sealing + + Global Stiffness Damping Damping “Low” “Mid” “High” ~ 150 Hz ~ 1000 Hz ~ 10,000 Hz Log Frequency Slide 82011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  9. 9. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies • Vehicle Interior Noise Simulation • NVH Principles: Applications • Closing Remarks Slide 92011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  10. 10. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 102011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  11. 11. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 112011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  12. 12. Structure Borne NVH Basics RECEIVER PATH SOURCE Slide 122011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  13. 13. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 132011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  14. 14. Single Degree of Freedom Vibration APPLIED FORCE F = FO sin 2 π f t 1 + (2ζ f fn ) 2 TR = FT / F = (1 − f fn ) + (2ζ f fn ) 2 2 2 2 m Transmitted Force k c FT ζ = fraction of critical damping fn = natural frequency k m f = operating frequency Slide 142011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  15. 15. Vibration Isolation Principle 4 0.1 APPLIED FORCE Transmissibility Ratio 0.15 F = FO sin 2 π f t 3 m TR = FT / F 0.25 2 k c FT Transmitted 0.375 Force 0.5 1.0 1 Isolation Region Isolation Region 0 0 1 1.414 2 3 4 5 Frequency Ratio (f / fn) Slide 152011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  16. 16. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 162011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  17. 17. NVH Source ConsiderationsSuspension Powertrain Two Main Sources Slide 172011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  18. 18. Typical NVH Pathways to the Passenger PATHS FOR STRUCTURE BORNE NVH Slide 182011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  19. 19. Structure Borne NVH Sources Slide 192011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  20. 20. Structure Borne NVH Sources Primary Consideration: Reduce the Source first as much as possible because whatever enters the structure is transmitted through multiple paths to the receiver. Transmission through multiple paths is more subject to variability. Slide 202011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  21. 21. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 212011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  22. 22. Receiver Considerations Subjective to Objective Conversions Subjective NVH Ratings are typically based on a 10 Point Scale resulting from Ride Testing Receiver Sensitivity is a Key Consideration A 2 ≈ 1/2 A 1 Represents 1.0 Rating Change TACTILE: 50% reduction in motion SOUND : 6.dB reduction in sound pressure level ( long standing rule of thumb ) Slide 222011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  23. 23. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 232011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  24. 24. Symbolic Model of Unibody Passenger Car 8 Degrees of Freedom 2 4 8 1 3 5 6 7 Total 2178.2 Kg (4800LBS) Tires 350.3 N/mmMass Sprung 1996.7 Kg KF 43.8 N/mm Unsprung 181.5 Kg (8.33% of Total) KR 63.1 N /mm Powertrain 181.5 Kg Beam mass lumped on grids like a beam M2,3,4 =2 * M1,5 Slide 24 From Reference 6 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  25. 25. 8 Degree of Freedom Vehicle NVH ModelEngine Mass 8 Engine Flexible Beam for BodyIsolator1 2 3 4 5 Suspension Springs 6 7 Wheels Tires Slide 252011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  26. 26. 8 Degree of Freedom Vehicle NVH Model Force Applied to Powertrain Assembly Feng 81 2 3 4 5 6 7 Forces at Powertrain could represent a First Order Rotating Imbalance Slide 262011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  27. 27. Engine Isolation Example Response at M id Car 1.0000 Constant Force Load; F~A 15.9 Hz 8.5 HzVelocity (mm/sec) 0.1000 7.0 Hz 0.0100 0.0010 2 4 8 1 3 5 6 7 700 Min. RPM First Order Unbalance 0.0001 Operation Range of Interest 5.0 10.0 15.0 20.0 Frequency Hz Slide 27 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  28. 28. Concepts for Increased Isolation “Double” isolation is the typical strategy for further improving isolation of a given vehicle design. Second Level of Isolation is at Subframe to Body Mount Subframe is Intermediate Structure Suspension Bushing is first level Slide 282011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  29. 29. 8 Degree of Freedom Vehicle NVH Model Removed Double Isolation Effect 81 2 3 4 5 Wheel 6 Mass 7 Removed Slide 292011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  30. 30. Double Isolation Example Vertical Response at DOF3 6.0E+00 Base Model 5.0E+00 (mm/sec) Without Double_ISO 4.0E+00 2 4 8 1 3 5 6 7 3.0E+00 Velocity 1.414*fn 2.0E+00 1.0E+00 0.0E+00 5.0 10.0 15.0 20.0 Frequency Hz Slide 302011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  31. 31. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 312011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  32. 32. Mode Management ChartEXCITATION SOURCES Inherent Excitations (General Road Spectrum, Reciprocating Unbalance, Gas Torque, etc.) Process Variation Excitations (Engine, Driveline, Accessory, Wheel/Tire Unbalances) 0 5 10 15 20 25 30 35 40 45 50 First Order Wheel/Tire Unbalance Hz V8 Idle Hot - ColdCHASSIS/POWERTRAIN MODES Suspension Hop and Tramp Modes Ride Modes Suspension Longitudinal Modes Powertrain Modes Exhaust Modes 0 5 10 15 20 25 30 35 40 45 50 HzBODY/ACOUSTIC MODES Body First Torsion Steering Column First Vertical Bending Body First Bending First Acoustic Mode 0 5 10 15 20 25 30 35 40 45 50 Hz (See Ref. 1) Slide 32 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  33. 33. 8 Degree of Freedom Vehicle NVH Model Bending Mode Frequency Separation 81 2 3 4 5 Beam Stiffness was adjusted to align Bending Frequency with Suspension 6 7 Modes and then progressively separated back to Baseline. Slide 332011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  34. 34. 8 DOF Mode Separation Example Response at Mid Car 18.2 Hz Bending 13.Hz Bending 100.00 10.6 Bending 2 4 8 1 3 5Velocity (mm/sec) 6 7 10.6 Hz 10.00 13.0 Hz 18.2 Hz 1.00 0.10 5 10 15 20 Frequency Hz Slide 34 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  35. 35. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 352011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  36. 36. Mount at Nodal Point First Bending: Nodal Point Mounting Example Front input forces Rear input forces Locate wheel centers at node points of the first bending modeshape to prevent excitation coming from suspension input motion. Slide 362011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  37. 37. Mount at Nodal Point First Torsion: Nodal Point Mounting Examples Side View Rear View Passenger sits at Engine node point for First Torsion. Transmission Mount of a 3 Mount N-S P/T is near the Torsion Node. Slide 372011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  38. 38. Powertrain Bending Mode Nodal Mounting1 2 3 4 5 6 7 Mount system is placed to support Powertrain at the Nodal Locations of the First order Bending Mode. Best compromise with Plan View nodes should also be considered. Slide 38 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  39. 39. 8 Degree of Freedom Vehicle NVH Model Bending Node Alignment with Wheel Centers Redistribute Beam Masses 8 to move Node Points to Align with points 2 and 41 2 3 4 5 6 7 Slide 392011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  40. 40. First Bending Nodal Point Alignment Response at Mid-Car 4.0E+00 Node Shifted 4 Base Model 8 2 (m m /sec) 1 3 5 6 7 3.0E+00 2.0E+00Velocity 1.0E+00 0.0E+00 5.0 10.0 15.0 20.0 Frequency Hz Slide 402011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  41. 41. Low Frequency Basics • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 412011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  42. 42. Dynamic Absorber Concept Auxiliary Spring-Mass-Damper m = M / 10 x x SDOF 2DOF M M YO YO Slide 422011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  43. 43. Powertrain Example of Dynamic Absorber Anti-Node Identified at end of Powerplant k c m Absorber attached at anti-node acting in the Vertical and Lateral plane. Tuning Frequency = √ k/m Slide 43 [Figure Courtesy of DaimlerChrysler Corporation]2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  44. 44. Baseline Sound Level Baseline Sound Level 63 Hz Dynamic Absorber 63 Hz Dynamic Absorber 63 + 110 Hz Absorbers 63 + 110 Hz Absorbers10dB Slide 44 [Figure Courtesy of DaimlerChrysler Corporation]2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  45. 45. Low Frequency Basics - Review • Source-Path-Receiver Concept • Single DOF System Vibration • NVH Source Considerations • Receiver Considerations • Vibration Attenuation Strategies Provide Improved Isolation Mode Management Nodal Point Mounting Dynamic Absorbers Slide 452011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  46. 46. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics Alan Duncan • Live Noise Attenuation Demo • Case Studies • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Slide 462011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  47. 47. Mid Frequency NVH Fundamentals This looks familiar! Frequency Range of Interest has changed to 150 Hz to 1000 Hz Slide 472011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  48. 48. Typical NVH Pathways to the Passenger PATHS FOR STRUCTURE Noise Paths are the BORNE Noise Paths are the same as Low same as Low NVH Frequency Region Frequency Region Slide 482011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  49. 49. Mid-Frequency Analysis Character Structure Borne Noise Airborne Noise • Mode separation is less practical in • Mode separation is less practical in High modal density mid-frequency mid-frequency and coupling in source, path and • New Strategy is Effective Isolation: • New Strategy is Effective Isolation: receiver Achieved by reducing energy transfer Achieved by reducing energy transfer locally between source and receiver at locally between source and receiver at key paths. key paths.Response Absorption + Local Stiffness Mass + + Global Stiffness Damping Sealing “Low” “Mid” “High” ~ 150 Hz ~ 1000 Hz Log Frequency ~ 10,000 Hz Slide 49 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  50. 50. Mid-Frequency Analysis Character Control Measures for Mid Frequency Concerns Effective Isolation Attenuation along Key Noise Paths Slide 502011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  51. 51. Mid-Frequency Analysis Character Control Measures for Mid Frequency Concerns Effective Isolation Attenuation along Key Noise Paths Slide 512011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  52. 52. Isolation Effectiveness Classical SDOF: Rigid Source and Receiver “Real Structure” 1.0 Flexible (Mobile) Source and Transmissibility Ratio Receiver Isolation Region Isolation Region f/fn 1.0 1.414 10.0 Effectiveness deviates from the classical development as resonances occur in the receiver structure and in the foundation of the source. Slide 522011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  53. 53. Mobility• Mobility is the ratio of velocity response at the excitation point on structure to the force applied in the direction of the velocity Velocity Mobility = Force• Mobility, also called Admittance, characterizes Dynamic Stiffness of the structure at load application point Frequency * Displacement Mobility = Force Frequency = Dynamic Stiffness Slide 53 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  54. 54. Isolation• The isolation effectiveness can be quantified by a theoretical model based onanalysis of the SOURCE - PATH - RECEIVER transfer across an isolator• Transmissibility Ratio (TR) is used to objectively define measure of isolation Force from source with isolator TR = Force from source without isolator V Receiver Vr V Receiver Vr V Fr Fr Fs = Yi + Y r + Y s F ir V ir Fs Vs Isolator V is Source F is V F s= Fs Yr +Ys Vs Source Slide 54 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  55. 55. Isolation Force from source with an isolator Receiver Vm TR = Force from source without an isolator Fm TR =  ( Y r + Y s ) / ( Y i + Y r + Y s )  F im V im Isolator V if Y r : Receiver mobility F if Y i : Isolator mobility Y s : Source mobility Ff Vf Source • For Effective Isolation (Low TR) the Isolator Mobility must exceed the sum of the Source and Receiver Mobilities. Recall that Y ∝1 K Slide 552011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  56. 56. Designing Noise Paths 1 1 1 1 1 TR =  ( + ) / ( + + ) K body K source K body K iso K source K source K body K iso K iso 1.0 5.0 20.0 1.0 0.67 0.55 0.51 5.0 0.55 0.29 0.20 20.0 0.51 0.20 0.09Generic targets:body to bushing stiffness ratio of at least 5.0source to bushing stiffness ratio of at least 20.0 Slide 562011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  57. 57. Body-to-Bushing Stiffness Ratio Relationship to Transmissibility 0.6 For a source ratio of 20 Transmissibility Ratio TR 0.5 0.4 Target Min. = 5 0.3 gives TR = .20 0.2 0.1 0 1 2 3 4 5 6 7 8 9 10 Stiffness Ratio; K body / K iso Slide 572011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  58. 58. Mid-Frequency Analysis Character Control Measures for Mid Frequency Concerns Effective Isolation Attenuation along Key Noise Paths Slide 582011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  59. 59. Identifying Key NVH PathsKey NVH paths are identified by Transfer Path Analysis (TPA) Acoustic Acoustic Transfer Transfer Fi Break the system at the points where the forces enter the body (Receiver) Operating loads Operating loadsTotal Acoustic Response is summation of partial responses over all noise paths Pt = Σ paths [Pi ] = Σ paths [ (P/F) i * Fi ] Slide 592011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  60. 60. Designing Noise Paths P/V Acoustic Transfer (P/F)i Acoustic Transfer (P/F)i P/F V/F F F (Kbody) F F F F Fi F Operating loads create Forces (Fi) into body at All noise paths Pt = Σ paths [Pi ] = Σ paths [ Fi * (P/F) i ] = Σ paths [ Fi * (P/V) i * (V/F) i ]Measurement Parameters Generic TargetsP/F Acoustic Sensitivity 50 - 60 dBL/NV/F Structural Point Mobility 0.2 to 0.3 (Receiver Side) mm/sec/N Slide 602011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  61. 61. “Downstream” Effects: Body Panels Recall for Acoustic Response Pt Pt = Σ paths [Pi ] = Σ paths [ Fi * (P/V) i * (V/F) i ](P/V)i ! “Downstream” Dynamics (Body Panel) : Three Typical Effects: 1. Panel Stiffness Increased Stiffness 3. Panel Acoustic Contribution 2. Panel Damping Increased Damping Slide 61 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  62. 62. Generic Noise Path Targets K body K source > 5.0 > 20.0 K iso K iso Structural Mobility < 0.2 to 0.3 mm/sec/N Acoustic 50 - 60 < Sensitivity dBL/N Primary: Minimize the Source Force < 1.0 N Panel Damping Loss Factor > .10 Slide 622011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  63. 63. Final Remarks on Mid Frequency Analysis• Effective isolation at dominant noise paths is critical• Reduced mobilities at body & source and softened bushing are key for effective isolation• Mode Separation remains a valid strategy as modes in the source structure start to participate• Other means of dealing with high levels of response (Tuned dampers, damping treatments, isolator placement at nodal locations) are also effective Slide 63 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  64. 64. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies Greg Goetchius • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Slide 642011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  65. 65. Tool Box Demo Test Results Toolbox Demo Noise Test Results 90 85 80 70 68 SPL (dBA) 63 61 60 55 50 47 40 39 30 1) Baseline: 2) Imbalance + 3) No Imbalance, 4) No Imbalance, 5) No Imbalance + 6) #5 + Absorption 7) #6 + Insulator Imbalance, No Isolation No Isolation No Isolation + Isolation + Mat Isolation Damping Damping Slide 652011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  66. 66. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies Kiran Govindswamy • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Slide 662011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  67. 67. “Time Domain” Transfer Path Analysis VINS (Vehicle Interior Noise Simulation) Excitation Transfer Behaviour Interior Noise Airborne Loudspeaker Noise Share Airborne Path Microphones FEV FEV Overall Power Train Noise Interior Noise Intake&Exhaust Noise ... Engine Mount Vehicle Structure-Borne Path Pi Power Train Vibration Drive Line Vibration Structureborne Overall Vehicle Transfer Function ... Noise Share Slide 672011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  68. 68. “Time Domain” Transfer Path Analysis VINS (Vehicle Interior Noise Simulation) Overall Structure-Borne Sound Transmission Resultant Dynamic Mount Stiffness ae ab Fb Mount Apparent Mass Vehicle Body Engine Excitation Transmissibility of Body Test Bench Impact Test abody Fbody Pinterior aengine = Pinterior aengine abody Fbody Resultant Dynamic Mount Stiffness Slide 682011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  69. 69. “Time Domain” Transfer Path Analysis VINS: Correlation (Full Load Speed Sweep) Slide 692011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  70. 70. “Time Domain” Transfer Path Analysis VINS: Application to “Idle Modulation Noise” Slide 702011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  71. 71. “Time Domain” Transfer Path Analysis VINS: Application to “Idle Modulation Noise” Slide 712011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  72. 72. “Time Domain” Transfer Path Analysis VINS: Application to “Transient Diesel Clatter” Measurement VINS VINS-SBN VINS-ABN Slide 722011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  73. 73. “Time Domain” Transfer Path Analysis VINS: Application to “Transient Diesel Clatter” Mic. left Mic. right Mic. top Mic. bottom Mic. front Mic. rear Intake orif. Exhaust tp. Left mnt. Right mnt. RR A RR B Trans. link Slide 732011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  74. 74. HEV, PHEV, ReEV, and EV NVH Coasting G D C Constant D C D C G speeds A D Acceleration B F A D D Drive-away C B F Start & A C F A F D idle B E B G Red light E A (Stop) ICE ICE Start/Stop Regeneration Power AER stopped idling ICE Batt. Charging Assist • A: Global powertrain vibration B: Driveline vibration • C: Noise of HEV specific components D: Magnetic noise E-Motor/(Generator) • E: Noise of accessories F: Gearbox rattle noise due to • G: Noise pattern changeover ICE (non-uniformity) and E-Motor Slide 742011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  75. 75. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies • Interior Noise Diagnosis using VINS • NVH Principles: Applications Jianmin Guan • Closing Remarks Slide 752011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  76. 76. NVH Principles: Application Example Introduction Slide 76Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  77. 77. Quietness during Idle and Electric-Vehicle Operation Root Cause Diagnostics: 1. Water pump in the inverter cooling system 2. Electromagnetic noise of the motor, the inverter, and other units Reduce Inverter Water Pump Loads: 1. Reduce pump impeller imbalance 2. Redesign bearing structure 3. Changing motor structure Improve Isolation from Body: 1. Install rubber isolator 2. Increase mounting bracket rigidity 3. Improve Inverter case Slide 77Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  78. 78. Quietness during Idle and Electric-Vehicle Operation Root Cause Diagnostics: 1. Water pump in the inverter cooling system 2. Electromagnetic noise of the motor, the inverter, and other units Reduce Inverter Water Pump Loads: 1. Reduce pump impeller imbalance 2. Redesign bearing structure Reduce 3. Changing motor structure Source Effective Isolation Improve Isolation from Body: 1. Install rubber isolator Attach. Stiffness 2. Increase mounting bracket rigidity 3. Improve Inverter case Downstream Slide 78Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  79. 79. Engine Start Vibration Root Cause Diagnostics: 1. Engine torque fluctuations 2. Engine torque reaction forces Reduce Torque Fluctuation: 1. Change intake valve closing timing 2. Control piston stop position 3. Adjust injected fuel volume and ignition timing Reduce Effect of Engine Loads: 1. Operating MG1 at high torque during engine start 2. Implement vibration-reducing motor control 3. Use two stage hysteretic torsional damper 4. Shorten distance between principal elastic axis and center of gravity of power plant Slide 79Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  80. 80. Engine Start Vibration Root Cause Diagnostics: 1. Engine torque fluctuations 2. Engine torque reaction forces Reduce Torque Fluctuation: 1. Change intake valve closing timing 2. Control piston stop position 3. Adjust injected fuel volume and ignition timing Reduce Source Mode Manage. Reduce Effect of Engine Loads: 1. Operating MG1 at high torque during engine start Damper 2. Implement vibration-reducing motor control 3. Use two stage hysteretic torsional damper 4. Shorten distance between principal elastic axis and center of gravity of power plant Effective Isolation Slide 80Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  81. 81. 2nd Order Engine Induced Boom Root Cause Diagnostics: 1. 2nd order couple of the reciprocating inertia of piston 2. THS II Trans 50 mm longer and 35 kg heavier 3. Lower power plant bending mode 4. Requires 1.5X higher mount rates Reduce Effect of 2nd order Couple: 1. Increase power plant bending mode 2. Move mount to a nodal point 3. Embed mounts inside cross member 4. Reduces distance from principle elastic axis to CG 5. Optimized vertical to lateral rate ratio Slide 81Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  82. 82. 2nd Order Engine Induced Boom Root Cause Diagnostics: 1. 2nd order couple of the reciprocating inertia of piston 2. THS II Trans 50 mm longer and 35 kg heavier 3. Lower power plant bending mode 4. Requires 1.5X higher mount rates Mode Manage. Reduce Effect of 2nd order Couple: 1. Increase power plant bending mode Nodal 2. Move mount to a nodal point Mounting 3. Embed mounts inside cross member Effective 4. Reduces distance from principle Isolation elastic axis to CG 5. Optimized vertical to lateral rate ratio Slide 82Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  83. 83. Engine Radiated Noise Root Cause Diagnostics: 1. 24th MG2 order excitation 2. Lower MG2 reduction gear ratio 3. Lower transmission bending mode - two key modes identified Reduce 24th order Loads: Arranged permanent magnets in V shape with optimized angle Reduce Effect of 24th order Loads: 1. Modified Trans case to improve modes 2. Added dynamic damper at a high amp. point on Trans case 3. Added ribs in high radiating area of Trans case Slide 83Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  84. 84. Engine Radiated Noise Root Cause Diagnostics: 1. 24th MG2 order excitation 2. Lower MG2 reduction gear ratio 3. Lower transmission bending mode - two key modes identified Reduce Reduce 24th order Loads: Source Arranged permanent magnets in V shape with optimized angle Mode Reduce Effect of 24th order Loads: Manage. 1. Modified Trans case to improve modes Damper 2. Added dynamic damper at a high amp. point on Trans case 3. Added ribs in high radiating area of Trans case Downstream Slide 84Copyright © 2009 SAE International 2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  85. 85. Structure Borne NVH Workshop • Introduction • Low Frequency Basics • Mid Frequency Basics • Live Noise Attenuation Demo • Case Studies • Interior Noise Diagnosis using VINS • NVH Principles: Applications • Closing Remarks Jianmin Guan Slide 852011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  86. 86. Structure Borne NVH: Concepts Summary • Source-Path-Receiver as a system 1. 1. Reduce Source Reduce Source 2. 2. Rank and Manage Paths Rank and Manage Paths 3. 3. Consider Subjective Response Consider Subjective Response • Effective Isolation • Mode Management • Nodal Point Placement • Attachment Stiffness • “Downstream” (Body Panel) Considerations Slide 862011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  87. 87. SAE 2011 NVH Conference Structure Borne NVH Workshop Thank You for Your Time! Q&A Slide 872011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  88. 88. Structure Borne NVH ReferencesPrimary 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 Make Quieter Vibration-free Vehicles”, Chrysler PR Article, March 1998.3. B. Dong, et. al., “Process to Achieve NVH Goals: Subsystem Targets via ‘Digital Prototype’ Simulations”, SAE 1999-01-1692, NVH Conference Proceedings, May 1999.4. S. D. Gogate, et. al., “’Digital Prototype’ Simulations to Achieve Vehicle Level NVH Targets in the Presence of Uncertainties’”, SAE 2001-01-1529, NVH Conference Proceedings, May 2001 Structure Borne NVH Workshop - on Internet At SAE www.sae.org/events/nvc/specialevents.htm Slide 88 WS + Refs. at www.AutoAnalytics.com/papers.html2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
  89. 89. Structure Borne NVH ReferencesSupplemental 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 Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, Sept. 19727. J. Y. Wong, Theory of Ground Vehicles, John Wiley & Sons, New York, 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 Paper No. 951374, (1995). Slide 892011 SAE Structure Borne NVH Workshop www.autoanalytics.com

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