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How Can Active Exhaust Systems Contribute to the Reduction of CO2 Emission and Comply with Future Pass-by Noise Limits?

Eberspaecher Exhaust Technology GmbH-Jan Krueger, Peter Wink, Maike Werner
  • Technical Paper
  • 2020-01-1534
To be published on 2020-06-03 by SAE International in United States
The pass-by noise limits of passenger vehicles according to ISO 362 / R51.3 will be further reduced by 2 dB in 2024 in Europe. Since the pass-by noise is substantially influenced by exhaust noise, the effort for the exhaust system needs to be increased. This results in systems with larger mufflers or higher backpressure. However, the more stringent CO2-emission targets require ever more efficient powertrains, which calls for rather lower backpressure to optimize the engine design. This paper describes, how compact active exhaust lines can support a design for low backpressure and high acoustic attenuation at the same time. For two passenger vehicle with gasoline engines, active exhaust lines are investigated in detail and the results are compared to the series production exhaust lines. Thus, in one exemplary case, the pass-by noise of a limousine could be reduced from 70 dB(A) to 68 dB(A) without any change in the vehicle design except the improved exhaust system.
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Development, System Integration and Experimental Investigation of an Active HVAC Noise Control System for a Passenger Car

Fraunhofer Institute LBF-Jonathan Millitzer, Valentin Mees, Christopher Ranisch
Hyundai Motor Company-Joong-Kwan Kim, Jinmo Lee, ChiSung Oh, Kang-Duck Ih
  • Technical Paper
  • 2020-01-1538
To be published on 2020-06-03 by SAE International in United States
Current developments in the automotive industry such as electrification and consistent lightweight construction increasingly enable the application of active control systems for the further reduction of noise in vehicles. As different stochastic noise sources such as rolling and wind noise as well as noise radiated by the ventilation system are becoming more noticeable and as passive measures for NVH optimization tend to be heavy and construction space intensive, current research activities focus on the active reduction of noise caused by the latter mentioned sources. This paper illustrates the development, implementation and experimental investigation of an active noise control system integrated into the ventilation duct system of a passenger car. Making use of a model-based design process, the development is based upon a holistic numerical simulation model integrating a reduced order acoustic model derived from finite element simulations as well as simplified loudspeaker and microphone characteristics. The numerical simulation assists the selection of a suitable loudspeaker microphone configuration, taking into account the available installation space and the integration of low-cost loudspeakers and MEMS microphones. The ventilation…
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Real-Time Capable Wind and Rolling Noise Synthesis for a More Realistic Vehicle Simulator Experience

Institute of Electronic Music & Acoustic-Julian Koch, Alois Sontacchi
MAGNA STEYR Fahrzeugtechnik AG & CO KG-Thorsten Bartosch, Werner Reinalter
  • Technical Paper
  • 2020-01-1546
To be published on 2020-06-03 by SAE International in United States
Nowadays a large proportion of the overall acoustic vehicle development takes place within virtual phases. Increasingly, projects require the auralization of virtual developed acoustics measures, e.g. from the disciplines of electro-acoustic, ride comfort, rolling noise or passive acoustic on dynamic or static driving simulators. In practice it turns out that in addition to engine noise also a realistic reproduction of rolling and wind noise is important. In this article, approaches to synthetic rolling and wind noise generators are discussed. We developed such real-time capable sound generators that are parametrizable according to arbitrary driving conditions. Furthermore, spacial reproduction of the driving sounds is achieved for binaural headphone, as well as for other arbitrary loudspeaker setups, like often found in driving simulators. Derived models and parametrization are based on measurements and recordings from several real vehicles. In order to facilitate the adjustment on specific vehicles and designing rolls thereof, the suggested parametrization is guided by a defined procedure. The influence of these noise components on an improved perception of the overall driving experience is objectified by means…
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Noise-Vibration (NVH) Analysis & Reduction in Traction Motors-PMSMs at the Design Stage

Tata Motors, Ltd.-Vishwanatha K. Rao
  • Technical Paper
  • 2020-01-1509
To be published on 2020-06-03 by SAE International in United States
Various electric propulsion systems are used in the industrial field. Recently, research focused on permanent magnet synchronous motors (PMSMs) because of their several advantages. There are various method to reduce Noise and Vibration of traction at the Design Stage of Motor. Noise reduction has constituted a difficult study point for the last years. A great part of this acoustic noise has electromagnetic origin. The harmonic spectrum of the PWM voltage supply is very rich and every frequency has direct effects on the motor acoustics and also Various Torques effect on the Motor, In this paper, the Design Stage of Electric Motor Describe the Design Specifications and Calculations For reduce Harmonics and unwanted Torque (Electromagnetic Forces) for NVH reduction. Such as two winding methods for the interior permanent-magnet synchronous motor for vehicle traction: concentrated winding and distributed winding. Both have merits and demerits, and both influences the motor’s performance. Also the paper presents and analyses the experimental acoustic noise of AC motors controlled by drives using different PWM techniques. Five criteria are taken into account: motor…
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Numerical Investigation of Narrow-Band Noise Generation by Automotive Cooling Fans

Chalmers University of Technology-Omar Fares, Huadong Yao
Volvo Car Group-Chenyang Weng, Linus Zackrisson, Magnus Knutsson
  • Technical Paper
  • 2020-01-1513
To be published on 2020-06-03 by SAE International in United States
Axial cooling fans are commonly used in electric vehicles to cool batteries with high heating load. One drawback of the cooling fans is the high aeroacoustic noise level resulting from the fan blades and the obstacles facing the airflow. To create a comfortable cabin environment in the vehicle, and to reduce exterior noise emission, a low-noise installation design of the axial fan is required. The purpose of the project is to develop an efficient computational aeroacoustics (CAA) simulation process to assist the cooling-fan installation design. This paper reports the current progress of the development, where the narrow-band components of the fan noise is focused on. Two methods are used to compute the noise source. In the first method the source is computed from the flow field obtained using the unsteady Reynolds-averaged Navier-Stokes equations (unsteady RANS, or URANS) model. In the second method, the azimuthal modes of the flow field obtained using the steady RANS with the moving reference frame model are treated as the sound source. While the first method is able to resolve any…
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Inter-Laboratory Characterization of Biot Parameters of Poro-Elsastic Materials for Automotive Applications

Autoneum Holding AG-Francesca Ronzio, Claudio Bertolini
Faurecia S.A.-Minh Tan Hoang, Ludovic Dejaeger
  • Technical Paper
  • 2020-01-1523
To be published on 2020-06-03 by SAE International in United States
Automotive suppliers provide multi-layer trims mainly made of porous materials. They have a real expertise on the characterization and the modeling of poro-elastic materials. A dozen parameters are used to characterize the acoustical and elastical behavior of such materials. The recent vibro-acoustic simulation tools enable to take into account this type of material but require the Biot parameters as input. Several characterization methods exist and the question of reproducibility and confidence in the parameters arises. A Round Robin test was conducted on three poro-elastic material with four laboratories. Compared to other Round Robin test on the characterization of acoustical and elastical parameters of porous material, this one is more specific since the four laboratories are familiar with automotive applications. Methods and results are compared and discussed in this work. Finally some guidelines are drawn to improve the confidence in the characterized parameters and to compare them under similar conditions possibly adapted to the final application.
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Innovative Acoustic Material Concept Integration Into Vehicle Design Process

Odenwald-Chemie GmbH-Michael Feist-Muench
dBVibroAcoustics-Denis Blanchet
  • Technical Paper
  • 2020-01-1527
To be published on 2020-06-03 by SAE International in United States
Integration of acoustic material concepts into vehicle design process is an important part of full vehicle design. The ability to assess the acoustic performance of a particular sound package component early in the design process allows designers to test various designs concepts before selecting a final products. This paper describes an innovative acoustic material concept which is easily integrated in a design process through the use of a database of Biot parameters. Biot parameters are widely used in the automotive industry to describe the physical interactions between the acoustics waves travelling through foams, fibers or metamaterials and the solid and fluid phase of these poro-elastic materials. This new acoustic material concept provides a combination of absorption, transmission loss and added damping on the panel it is attached to. It has shown unique vibro-acoustics performance when tested on a German car manufacturer flagship vehicle and provides the ability to reduce the space needed for sound package component compared with classical solutions.
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Impact of Manufacturing Inaccuracies on the Acoustic Performance of Sound Insulation Packages With Plate-like Acoustic Metamaterials

Hamburg University of Applied Sciences-Felix Langfeldt, Wolfgang Gleine
  • Technical Paper
  • 2020-01-1562
To be published on 2020-06-03 by SAE International in United States
Thin plate-like metamaterials (e.g. membrane-type acoustic metamaterials or inhomogeneous plates) have a high potential for improving the sound transmission loss of sound insulation packages, especially in the challenging low-frequency regime. These types of metamaterials have been previously shown to achieve very high sound transmission loss values which can exceed the corresponding mass-law values considerably. However, like many other metamaterial realizations, their extraordinary acoustical performance relies on the periodicity of the sub-wavelength sized unit cells. In particular, for plate-like acoustic metamaterials (PAM) most theoretical and numerical investigations assume a perfect placement of equal added masses - an idealization which cannot be achieved in industrial manufacturing of these metamaterials. This contribution investigates the impact of randomized inaccuracies that can occur in manufacturing on the sound reduction behavior of PAM. First, a numerical model of a finite sized PAM is validated using sound transmission loss measurement data. Then, the simulation model is modified to incorporate randomly varying geometrical parameters of the added masses (such as mass placement, size, etc.). The parameters are randomized according to a Gaussian distribution…
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Simulation Process for the Acoustical Excitation of DC-Link Film Capacitors in Highly Integrated Electrical Drivetrains

AVL LIST GmbH-Julian Pohn
BMW Group-Maximilian Herrnberger, Jakob Bonart, Roland Lichtinger
  • Technical Paper
  • 2020-01-1500
To be published on 2020-06-03 by SAE International in United States
The advancing electrification of the powertrain is leading towards new challenges in the field of acoustics. Film capacitors used in power electronics are a potential source of high-frequency interfering noise since they are exposed to voltage harmonics. These voltage harmonics are caused by semiconductor switching operations that are necessary to convert the DC voltage of the battery into three-phase alternating current for the electrical machine. In order to predict the acoustic characteristics of the DC-link capacitor at an early stage of development, a multiphysical chain of effects has to be addressed to consider electrical and mechanical influences. In this paper, a new method to evaluate the excitation amplitude of film capacitor windings is presented. The corresponding amplitudes are calculated via an analytical force based on electromechanical couplings of the dielectric within film capacitors. As a next step, these calculated excitation amplitudes can be used in a FE simulation by applying volumetric strains on capacitor windings. This allows to consider the structural dynamic properties of different capacitor geometries. In order to lower the computational costs, a…
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Squeak Noise Prediction of a Door Trim Panel Using Harmonic Balance Method

ARRK Engineering-Arno Fuchs
TUM-Chair of Vibroacoustics-Steffen Marburg
  • Technical Paper
  • 2020-01-1577
To be published on 2020-06-03 by SAE International in United States
Squeak and rattle noise in a vehicle's interior is perceived as an annoying sound by customers. Since persistent noise (e.g. engine, wind, or drive train noise) has been reduced continuously during the last decades, the elimination of sounds, which have their origin in the vehicle's interior components, is getting more important. Therefore, noise prediction based on simulation models is useful, since design changes can be realized at lower costs in early virtual development phases. For this task, linear simulation methods are state of the art for the identification of noise risk, but in general without knowing if a sound is audible or not. First approaches have been developed based on the Harmonic Balance Method to predict squeak noise and assess their audibility. This paper presents vibroacoustic measurements at a door trim panel for squeaking and non-squeaking configurations. Vibrations are excited harmonically by a force controlled low noise shaker. The system response is measured in a semi-anechoic chamber by acceleration sensors and audibility is assessed. Additionally, a 3D finite element model is built and the Harmonic…