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Concept Study on Windshield Actuation for Active Control of Wind Noise in a Passenger Car

Fraunhofer Institute LBF-Thorsten Koch, Jonathan Millitzer, William Kaal PhD, Georg Stoll, Matthias Schmidt
Hyundai Motor Company-Joong-Kwan Kim, Jinmo Lee, ChiSung Oh, Kang-Duck Ih
  • Technical Paper
  • 2020-01-1535
To be published on 2020-06-03 by SAE International in United States
The windshield is an integral part of almost every modern passenger car. Combined with current developments in the automotive industry such as electrification and the integration of lightweight material systems, the reduction of interior noise caused by stochastic and transient wind excitation is deemed to be an increasing challenge for future NVH measures. Active control systems have proven to be a viable alternative compared to traditional passive NVH measures in different areas. However, for windshield actuation there are neither comparative studies nor actually established actuation concepts available to the automotive industry. Based upon a numerical simulation of an installed windshield of a medium-sized car, this paper illustrates a conceptual study of both the evaluation of optimal positioning as well as a consideration of different electromechanical activation measures. A simulation model of the installed windshield is gained from an experimental modal analysis of both the windshield in free-free condition as well as in its installed configuration. The experimental data serves the frequency domain model update process of a finite element model of the installed windshield. A…
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NVH Comfort of Range Extenders for Electric Vehicles

FEV Europe GmbH-Christoph Steffens, Georg Eisele, Frank Wolter
  • Technical Paper
  • 2020-01-1551
To be published on 2020-06-03 by SAE International in United States
The most appreciated driving characteristics of electric vehicles are the quietness and spontaneous torque rise of the powertrain. The application of range extenders (REX) with internal combustion engines (ICEs) to increase the driving range is a favourable solution regarding costs and weight, especially in comparison with larger battery capacities. However, the NVH integration of a REX is challenging, if the generally silent driving characteristics of electric vehicles shall remain preserved. This paper analyses key NVH aspects for a REX design and integration to fulfil the high expectations regarding noise and vibration comfort in an electric vehicle environment. The ICE for a REX is typically dimensioned for lower power outputs, incorporating a low number of cylinder units, which is even more challenging concerning the NVH integration. The basic REX concept is evaluated by considering power and fuel efficiency demands in combination with an interior noise forecast. It will be explained that sophisticated, innovative technologies are required on component and vehicle side to ensure best possible NVH comfort. On component side, essential excitations must be addressed. In…
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Numerical Investigation of Tonal Noise at Automotive Side Mirrors Due to Aeroacoustic Feedback

Daimler AG-Alexander Schell, Mark Eiselt
  • Technical Paper
  • 2020-01-1514
To be published on 2020-06-03 by SAE International in United States
In addition to the typical broadband noise character of wind noise, tonal noise phenomena can be much more disruptive, regardless of the overall interior noise quality of the vehicle. Whistling sounds usually occur by flow over sharp edges and resonant gaps, but can also be caused by the feedback of sound waves with laminar boundary layers or separation bubbles and the resulting frequency-selective growth of boundary layer instabilities. Such aeroacoustic feedback can e.g. occur at the side mirror of a vehicle and one compellingly needs the coupling of acoustic and flow field. A compressible large eddy simulation (LES) is in principle suitable but one has to take care of any numerical artifacts which can disturb the entire acoustic field. This paper describes the possibility to resolve aeroacoustic feedback with a commercial 2nd/3rd order finite volume CFD code. A zonal RANS/LES approach is used to ensure a realistic flow around the exterior side mirror mounted at a Mercedes-Benz C-Class. The provided compressible LES are using non-reflecting boundary conditions in combination with a sponge zone approach to…
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A Case Study on Reducing the Fuel Pulse Noise from Gasoline Engine Injectors

FCA US LLC-Weiguo Zhang, Toon Tan, John Malicki, Glenn Whitehead
  • Technical Paper
  • 2020-01-1276
To be published on 2020-04-14 by SAE International in United States
Vehicle NVH performance is a very important consideration for vehicle buyers in the marketplace. There are many noise sources from the fuel system to generate noise in a vehicle. Among them, the pressure pulsations due to the rapid opening and closing of gasoline engine injectors can cause undesirable fuel pulse noise inside the vehicle cabin. As the pressure pulsation propagates in the fuel supply line toward to rear end of the vehicle, the pressure energy is transferred from fuel lines to the vehicle underbody through clips and into the passenger compartment. It is crucial to attenuate the pressure pulsation inside the fuel line to reduce the fuel pulse noise. In this paper, a case study on developing an effective countermeasure to reduce the objectionable fuel pulse noise of a V8 gasoline injection system is presented. First, the initial interior noise of a prototype vehicle was tested and the objectionable fuel pulse noise was exhibited. The problem frequency ranges with pulse and ticking noise content were identified. Several test iterations on root causing analysis and countermeasures…
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Further study of the vehicle rattle noise with consideration of the impact rates and loudness

Jilin University-Shuming Chen
SKL of Vehicle NVH and Safety Technology-Linyuan Liang, Peiran Li
  • Technical Paper
  • 2020-01-1261
To be published on 2020-04-14 by SAE International in United States
With the prevalent trend of the pure electric vehicle, vehicle interior noise has been reduced significantly. However, other noises become prominent in the cabin. Especially, the BSR (Buzz, Squeak and Rattle) noise generated by friction between parts and the clearance between components become the elements of complaints directly affect the quality of vehicles. Currently, the BSR noises are subjectively evaluated by experts, and the noise samples are simply labeled as ‘qualified’ or ‘unqualified’. Therefore, it is necessary to develop an evaluation model to assess the BSR noise objectively. In this paper, we study the vehicle rattle noise intensively. Several types of rattle noise were recording in a semi-anechoic room. The recorded signals were than processed in the LMS test lab. to extract the single impact segments. A pool of simulated signals with different impact rates (number of impacts per second) and vary loudness was established. To verify the universality of the assessment, the in-vehicle background noises were also recorded. The in-vehicle background noises were combined with the rattle noise samples to simulate the in-vehicle test…
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Road Noise Evaluation by Sound Quality Simulation Module

Geely Automobile Research Institute-Perry Gu, Jie Mao, Zhidong Chen, Zhi Ding, Lei Cheng, Zhenying Zhu, Hong Peng
  • Technical Paper
  • 2020-01-1275
To be published on 2020-04-14 by SAE International in United States
An objective evaluation of sound quality is a technical bridge connecting sound pressure level (SPL) and human auditory sensation. In this paper, an algorithm is proposed for calculating objective evaluation parameters of sound quality (including loudness, sharpness and articulation index), considering acoustic characteristics of human external ear, middle ear and inner ear to reflect auditory sensation. A sound quality simulation (SQS) module is coded according to the algorithm. The module is used for evaluating sound quality of road noise from an SUV in three steps. Firstly, interior noise is predicted by integrating finite-element method (FEM), hybrid FE-SEA method, and statistical energy analysis (SEA) for low frequency (20~315 Hz), medium frequency (315~500 Hz), and high frequency (>500 Hz) in 1/3 octave band, respectively. The predicted interior noise SPLs are compared with the measured results, with deviations less than 3dB in average. Secondly, the sound quality parameters are calculated using the predicted SPLs in the SQS module. The predicted and measured loudness, sharpness, and articulation index are compared, with average deviations less than 5%. Finally, the predicted…
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Enhanced Windshield NVH Modeling for Interior Cabin Noise

FCA US LLC-Ahmad Abbas, Wael Elwali, Aravindhan Thirukonda, Syed Haider, Francisco Sturla
  • Technical Paper
  • 2020-01-1100
To be published on 2020-04-14 by SAE International in United States
The windshield is an important component in vehicle NVH performance. It plays an integral role in affecting the interior cabin noise. The windshield acts as a large panel typically oriented near vertical at the front of vehicle’s acoustic cavity, hence modeling it appropriately is key to have a reliable prediction of cabin interior noise. The challenge of modeling the windshield accurately rises from the structural composition of different types of windshields. For automotive applications, windshield come in several structural compositions today. In this paper, we will discuss two types of windshield glass. First is a typical laminated glass with polyvinyl butyral (PVB) layer and second is a typical acoustic glass with PVB and vinyl layers. Acoustic glass improves acoustics characteristics of the glass in frequencies of ~ 1200 Hz to ~4000 Hz range. Low frequency interior cabin noise studied with FEA is typically below 500 Hz. The acoustic glass doesn’t provide any benefits in this range and in many cases we see an adverse contribution at lower frequencies since the acoustic windshield tend to be…
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Liftgate Structure Optimization to Minimize Contribution to Low Frequency Interior Noise

General Motors LLC-David Hamilton
General Motors LLC / Tata Consulting Service-Masani Sivakrishna, Bhaskar Gangu
  • Technical Paper
  • 2020-01-1264
To be published on 2020-04-14 by SAE International in United States
This paper presents the design development of a SUV liftgate with the intention of minimizing low frequency noise. Structure topology optimization techniques were applied both to liftgate and body FEA models to reduce radiated sound power from the liftgate inner surface. Topology results are interpreted into structural changes to the original liftgate and body design. Favorable results of sound power performance with reduced cost and mass is shown compared to baseline liftgate and baseline with TVA (tuned vibration absorber). This simulation includes finite element modeling of coupled fluid/structure interaction between the interior air cavity volume and liftgate structure. In addition to sound power minimization, multi-model optimization (MMO) was used on separate models simultaneously to preserve liftgate structural performance for several customer usage load cases.
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Headliner Trim Design Methodology Development with Finite Element Simulation and Optimization Considering Multi Domain Performance

Tata Technologies Ltd.-Ashish Sathaye, S. Vishnu, Suhas Patil, Prashant Banbare
  • Technical Paper
  • 2020-01-1099
To be published on 2020-04-14 by SAE International in United States
Passenger cars in the top segment have seen fast growth over the last few decades with an increasing focus on luxury, convenience, safety and the quality of driver experience. The Headliner is a decorative and functional trim system covering the underside of the roof panel. It enhances to the aesthetics and elegance of the car interiors. In premium vehicles, the headliner system has to suffice interior quietness and integrity apart from the performance and regulatory requirements. The Design Validation Plan requirements cover its contribution to the vehicle interior noise control, occupant safety, and perception of build quality. Contributions can be very significant and primarily be determined by design and material parameters. Also, Headliner interactions with an adjacent body in white structure is crucial from performance point of view. Various foam options are available with different functions such as structural, acoustic, and energy-absorption. Part thicknesses vary depending on the class of vehicle and respective demands. Foam locations and types greatly influences the proportional performance. Selection of each parameter in an efficient way is a critical task,…
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Engine Order Sound Simulation by Active Sound Generation for Electric Vehicles

SAE International Journal of Vehicle Dynamics, Stability, and NVH

General R&D Institute of China FAW Group Co., Ltd., China State Key Laboratory of Comprehensive Technology on Automobile Vibration and Noise & Safety Control, China-Yuntao Cao, Hangsheng Hou, Yingjie Liu, Lechao Tang, Yun Li
  • Journal Article
  • 10-04-02-0011
Published 2020-02-04 by SAE International in United States
In this article, an active sound generation (ASG) system is proposed to simulate engine order sound that is typically found in vehicles equipped with internal combustion engines. Based on an A-class electric SUV, a mathematical model simulating engine order sound is established, and a short-time Fourier transform and synthesis technique is implemented. An ASG hardware along with its main functional circuits is designed, and the control software is developed. The ASG system is configured based on the loudspeakers used by the vehicle’s audio system and the frequency response characteristics of the loudspeakers is obtained by testing. An interior sound design method simulating acceleration conditions is investigated in detail. The control method is formulated based on the interior noise characteristics in accordance with the engine order sound amplitude variation. By establishing a design process with an ASG calibration and evaluation method, the accuracy of the acoustic synthetic method is validated. In summary, this work provides an interior sound design process to simulate accelerating conditions for electric vehicles and has established a sound control, calibration, and evaluation…
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