Verification of a Resonating Structural Component s Contribution to NVH Phenomena

Transcription

1 at K a r l s r u h e I n s t i t u t e of Te c h n o l o g y Verification of a Resonating Structural Component s Contribution to NVH Phenomena June 26 th Univ.- Prof. Dr.-Ing. Dr. h. c. Albers, Dipl.-Ing. Manuel Bopp, Dr.-Ing. Behrendt IPEK 13. AVL Diagnose Symposium KIT The Research University in the Helmholtz Association

2 Agenda Introduction and Motivation Methodological Approach Exemplary Measurements Summary and Outlook Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

3 Karlsruhe Institute of Technology Location of Karlsruhe Karlsruhe 3

4 IPEK Karlsruhe Facts 2 professors and 1 managing director 10 research fields 3 chief engineers ~ 80 scientists 20 administration & technical staff education since 1996 over 120 Ph.D. 21 lectures over 350 student assistants ~2000 coached students equipment Automotive and Powertool test labs high performance computing test vehicles mech. & elec. workshops 4

5 IPEK Research Approach Research Fields Research Designs the Future. Drive Systems Tribology Systems Clutches and Brakes in Drive Systems Methods of Embodiment Design Development and Innovation Management Product Generation Engineering NVH and Vehicle Acoustics Lightweight Design Power Tools Validation of Technical Systems Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

6 Introduction and Motivation Challenges in Vehicle Development Source: Zeller et. al. Handbuch Fahrzeugakustik Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

7 Sound pressure level at K a r l s r u h e I n s t i t u t e of Te c h n o l o g y Introduction and Motivation Challenges in Vehicle Development Noise attributed to auxiliary components Noise attributed to ICE Speed Noise attributed to wind Source: Zeller et. al. Handbuch Fahrzeugakustik Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

8 Sound pressure level at K a r l s r u h e I n s t i t u t e of Te c h n o l o g y Introduction and Motivation Challenges in Vehicle Development Noise attributed to auxiliary components + electric powertrain Noticeable noise Speed Noise attributed to wind Source: Zeller et. al. Handbuch Fahrzeugakustik Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

9 Introduction and Motivation Challenges in Vehicle Development Combustion Electric Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

10 Frequency / Hz at K a r l s r u h e I n s t i t u t e of Te c h n o l o g y Introduction and Motivation Challenges in Vehicle Development Source: Albers, Behrendt, Ott; Comfort objectivation for NVH and acoustics by means of artificial neural networks, Automotive Acoustics Conference 2011 Excitation by electric drive (e.g. PMSM) Excitation by transmission (e.g. 1 Gear with 2 Stages) Speed Range ICE Speed Range electric drive Electrification of powertrain Excitation by ICE (e.g. 4 Cylinder) Resonances Engine speed / rpm Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

11 Introduction and Motivation Challenges in Vehicle Development New components and subsystems in new powertrain concepts New challenges regarding NVH behavior and driveability Noise phenomena without driver input and with no speed-correlation n No correlation! 11

12 Introduction and Motivation Challenges in Vehicle Development Disturbing NVH phenomena are often only discovered in a very late stage of development A fast and reliable localization of the source and relevant transfer paths is essential for time and cost efficient development If a resonance in the transfer path is found, its contribution to the overall phenomenon has to be measured 12

13 Introduction and Motivation Challenges in Vehicle Development Is the resonance responsible for the audible phenomenon? To what extent? Acceleration on component Soundpressure at driver position Causality? Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

14 Agenda Introduction and Motivation Methodological Approach Exemplary Measurements Summary and Outlook Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

15 Methodological Approach Arithmetic Basics The natural frequency of an oscillation can be described as: f eigen = 1 2π c m f eigen = 1 2π 3EI ml³ The frequency can be influenced by changes in mass or stiffness 15

16 g at K a r l s r u h e I n s t i t u t e of Te c h n o l o g y Methodological Approach Initial Measurement Initial Measurement Change Mass or Stiffness Second Measurement Analysis of Results 1. Initial Measurement First measurement with unmodified system Frequency Hz db Pa rpm Airborne noise in customer relevant position CN4 1::ID_256d_100h_::PT_EME_Drehzahl_Elektromaschine (CH6) Structure borne noise on suspected component Frequency Hz db rpm CN4 1::ID_256d_100h_::PT_EME_Drehzahl_Elektromaschine (CH6)

17 Methodological Approach Change Mass or Stiffness Initial Measurement Change Mass or Stiffness Second Measurement Analysis of Results 2. Change mass or stiffness of component Additional mass can usually be applied with low effort Stiffness can be changed by applying external force or an additional strut This almost always leads to additional mass Not practicable 17

18 g g at K a r l s r u h e I n s t i t u t e of Te c h n o l o g y Methodological Approach Second Measurement Initial Measurement Change Mass or Stiffness Second Measurement Analysis of Results 3. Second measurement m 0 Air borne Structure borne m Repeat first measurement with modified system Frequency Hz db Pa Frequency Hz db Airborne noise in customer relevant position Structure borne noise on suspected component Frequency Hz rpm CN4 1::ID_256d_100h_::PT_EME_Drehzahl_Elektromaschine (CH6) m m rpm CN4 1::ID_256d_100h_::PT_EME_Drehzahl_Elektromaschine (CH7) db Pa 10 Frequency Hz rpm CN4 1::ID_256d_100h_::PT_EME_Drehzahl_Elektromaschine (CH6) rpm CN4 1::ID_256d_100h_::PT_EME_Drehzahl_Elektromaschine (CH7) db

19 Methodological Approach Analysis of Results Initial Measurement Change Mass or Stiffness Second Measurement Analysis of Results 4. Analysis of Results Air borne Structure borne Analyze measurement data and influence of additional mass in detail Change in customer relevant position Causality! Pa Amplitude (RMS) 200e-6 100e-6 F F Order Kunstkopf_l:-Y m_0 Order Kunstkopf_l:-Y m_ Hz Derived Frequency 1 Amplitude g Amplitude (RMS) 25e-3 20e-3 10e-3 0 F F Order F1monoaxial:+Y m_0 Order F1monoaxial:+Y m_ Hz Derived Frequency 1 Amplitude

20 Agenda Introduction and Motivation Methodological Approach Exemplary Measurements Summary and Outlook Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

21 Exemplary Measurements Whisteling noise in passenger cabin In the example vehicle a high pitched tonal noise can be heard in the passenger cabin at ~24 km/h The 144 th order matches the 2 nd harmonic of the e-motor The e-motor itself does not show elevated levels Air borne at driver position Structure borne on EM 21

22 Exemplary Measurements Whisteling noise in passenger cabin TPA The rear bumper support has a resonance at the corresponding frequency Quelle: BMW 22

23 Exemplary Measurements Whisteling noise in passenger cabin Additional mass on the component moves the peak in the acceleration as well as in the soundpressure at the driver position Acceleration on component Acceleration on component 23

24 Exemplary Measurements Whisteling noise in passenger cabin Additional mass on the component moves the peak in the acceleration as well as in the soundpressure at the driver position Soundpressure in passenger cabin Acceleration on component Acceleration on component 24

25 Agenda Introduction and Motivation Methodological Approach Exemplary Measurements Summary and Outlook Dipl.-Ing. Manuel Bopp - Verification of a Resonating Structural Component s Contribution to NVH Phenomena

26 Summary and Outlook Summary A universal method for verifying a resonance s contribution to a certain NVH phenomenon has been defined The method is easily applicable and deliveres fast and definite results 26

27 Summary and Outlook Outlook The component is currently being further investigated with a laserscanning-vibrometer Results are compared with FEM simulations on different levels of abstraction 27

28 Summary and Outlook Outlook The underlying modal analysis could also be used in different application areas: Lifetime and fault monitoring diagnostics Scrutiny checks of structural components after accidents Material fault or impurity checks, also applicable for composite materials (as alternative to ultrasonic techniques) 28

29 Thank you for your attention! Contact Dipl.-Ing. Manuel Bopp Telefon: Fax: Web: 29