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Acoustic characteristics prediction and optimization of wheel resonators with arbitrary section

SAIC Motor Corporation Limited-Yimin Sun, Junlei Mao
Tongji University-Rong Guo, Tiantian Mi
  • Technical Paper
  • 2020-01-0917
To be published on 2020-04-14 by SAE International in United States
Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal simulation and test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics. Combing the transmission loss prediction theory and particle swarm algorithm, the structure parameters of the wheel resonator are optimized. A remarkable attenuation of tire cavity resonance can be observed through test results.
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A Holistic Approach to Develop a Modern High Power Density Diesel Engine to Meet Best-in-class NVH levels.

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Rajkumar Bhagate, Madhu Chalumuru
  • Technical Paper
  • 2020-01-0406
To be published on 2020-04-14 by SAE International in United States
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration and harshness (NVH) levels. This papers presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4 cylinder diesel engine. The base engine architecture was designed with NVH reduction features such as crank-offset, cast iron crankcase, stiffened ladder frame, structural oil pan and front cover. Piston skirt profile was optimized to reduce the slapping noise by carefully studying the secondary motion and skirt contact pressure. The plastic parts such as cylinder head cover and intake manifold were designed with closely spaced ribs and high wall thickness. Natural frequency targets for different parts were set for the entire engine at component level and system level and confirmed through simulations. High frequency acoustic simulation was carried out to identify and improve the areas of high surface velocity. "Acoustic holography" technology was extensively used to identify the areas of high noise radiation in the running engine. Based on the measurements, it was identified…
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Acoustic performance analysis of automotive HVAC duct designs using a Lattice-Boltzmann based method and correlation with Semi-anechoic chamber.

Dassault Systemes-Prasad Sivakumar, Adrien Mann, Minsuk Kim
FCA Engineering India Pvt., Ltd.-Sivaji Pasupuleti
  • Technical Paper
  • 2020-01-1263
To be published on 2020-04-14 by SAE International in United States
Acoustic comfort of automotive cabins has progressively become one of the key attributes of vehicle design, with wind noise and HVAC noise being two of the key contributors to noise levels heard inside the car. With the increasing prevalence of hybrid technologies and electrification and the associated reduction in powertrain noise levels, the industry has seen an increasing focus on understanding HVAC noise, as it is a main source of noise in the cabin if not the single one when the vehicle is stopped. The complex turbulent flow path through the ducts, combined with acoustic resonances can potentially lead to significant noise generation, both broadband and tonal. In order to avoid time consuming and expensive late stage design changes, or avoid being hit by low consumer rating ignoring the issues, it is important to identify potential problems early in the design process and take appropriate measures to rectify them. In this study, the noise characteristics of three HVAC duct designs are studied using a commercial CFD code based on the Lattice-Boltzmann method. The noise spectra…
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A method to evaluate the acoustic performance of the Pillar filler foam in a Truck cab

ESI North America-Praveen Jayasheela, Ricardo Alvarez
Volvo Group North America-Suresh Patra
  • Technical Paper
  • 2020-01-0505
To be published on 2020-04-14 by SAE International in United States
The truck cab is made of many structural members like a, b, c, hinge - pillar, rocker, roof rails, headliner, quarter panels, cross-members at the floor and other body panels. For an acoustic example, the source energy travels easily from one end to another end through pillars. To reduce these acoustic effects, the filler foams were added inside the pillars. The proper usage of filler design and filler material type produces the optimal sound response at the driver head space location. In this paper, an analytical method is used to evaluate the acoustic performance of the fillers as described above and the method also avoids the expensive full vehicle tests. The statistical energy analysis (SEA) model simulations and post-processing techniques were used to evaluate the results quickly with an acceptable level of accuracy. It has proven that the effect of the foam thickness and foam coverage area of the fillers can be evaluated and helped to achieve the optimal sound response at the driver head location.
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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
Objective evaluation of sound quality is the bridge connecting sound pressure level (SPL) and auditory sensation. The modified algorithm was proposed for objective evaluation parameters of sound quality (including loudness, sharpness and articulation index), considering the acoustic transfer functions of external ear, middle ear and inner ear to enhance the algorithm integrity and accuracy. The sound quality simulation (SQS) module was developed in accordance to the optimized algorithm. For evaluating the sound quality of road noise of an SUV, the full-spectrum interior noise was calculated by integrating finite-element method (FEM), FE-SEA method, and statistical energy analysis (SEA) for low frequency (20~300 Hz), middle frequency (300~500 Hz), and high frequency (above 500 Hz), respectively. The simulated and tested full-spectrum interior SPLs were correlated. The general deviations were below 3dB at each one-third central frequency. The sound quality of road noise was evaluated by SQS. The deviations of the simulated and tested loudness, sharpness, and articulation index were generally below 5%, which proved the accuracy of the optimized algorithm for the objective evaluation parameters of sound quality.…
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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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Air Induction Impact on Turbocharger Noise and Thermodynamic Performance

FCA US LLC-Shadi Saeed, Brian Butler, Mark Likich, Jeff Orzechowski
FEV Europe GmbH-Tobias Zimmermann
  • Technical Paper
  • 2020-01-0426
To be published on 2020-04-14 by SAE International in United States
The trend of improved FE and performance has led to industry growth of turbocharged engines and as a result, the need to address their undesirable attributes. This presents some unique engineering challenges as customer expectations for NVH, and other vehicle-level attributes, trend higher over time as well. Noise attenuation specific to turbocharged engines is uniquely challenging due to the types of noises they produce. Of specific concern, flow interaction between the induced air and compressor through a range of thermodynamic conditions can often result in objectionable "whoosh" noises within the Air Induction System (AIS). The traditional method for attenuation of this type of noise has been to use resonators which adds cost, weight and requires packaging space which is often at a premium in the under-hood environment. By improving our understanding of the root cause of the compressor whoosh noise, we hope to develop system design strategies that can prevent unwanted noise from being generated and avoid the need for traditional noise attenuation solutions. To investigate different flow metrics and their impact on compressor noise…
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ACOUSTC CHARACTERISTICS OF AUTOMOTIVE DAMPER DURING FLUID STRUCTURE AND STRUCTURAL INTERACTIONS

Gabriel India Ltd.-Ravi B
VIT ARAI-Swapnil S. Kulkarni
  • Technical Paper
  • 2020-01-0989
To be published on 2020-04-14 by SAE International in United States
Acoustic characteristics of hydraulic dampers used in passenger cars are investigated. Experimentation work is carried out with servo hydraulic machine. Semi-anechoic chamber is used to isolate damper, in order to study noise source in damper. Noise and vibration data analysis is performed with the help of OROS software which is specifically used for noise and vibration data acquisition and analysis. Noise and vibration tests are performed by various frequencies and amplitude excitation inputs given to damper. As a part of low to mid frequency excitation, the amplitude of damper excitation is 20 mm in rebound and 10 mm in compression stroke of damper with data contains multiple input frequencies namely 0.5, 1, 1.5, and 2 Hz. This test condition ensured that the noise is perceived to car cabin by means of damper rather than filtration unit attached to damper. As a part of high frequency excitation, damper is stroked at low amplitude and high frequency typically ±5 mm in rebound and compression stroke of damper, respectively where 5, 10 and 12 Hz are the input…
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Analysis of Vibroacoustic Behaviors and Torque Ripple of SRMs with Different Phases and Poles

Shenglong Hu, Xiaorui Hu
Tongji University-Shuguang Zuo
  • Technical Paper
  • 2020-01-0467
To be published on 2020-04-14 by SAE International in United States
In this paper, the vibroacoustic behaviors and torque ripple of switched reluctance motors (SRMs) with different phases and poles have been analyzed in detail. Also, the common four SRMs, i.e., three-phase 6/4 SRM, four-phase 8/6 SRM, five-phase 10/8 SRM, and six-phase 12/10 SRM, have been selected, which represent all the radial SRMs. First, the spatial-temporal distribution characteristics of radial force in SRMs were revealed by virtue of the analytical derivation, which was validated by the 2D Fourier decomposition based on the FEM results of radial force. Second, a multiphysics model, which was composed of an electromagnetic field, mechanical field, and acoustic field, was established to predict the noise behaviors of SRMs with different phases and poles. Third, the relationship between the torque ripple and the phases of SRMs, and the relationship between the noise and the radial force / phases / poles are all analyzed. Finally, the results show that the spatial orders of the radial forces, which are in all radial SRMs with any possible phase and pole, are kNs/(2Q) and the frequencies are…
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Pass-by Noise Prediction of a Vehicle

CAE-NVH, Product Development, Royal Enfield, Chennai.-RajaGopal B., Santosh Gannu, Abhilash M, GS Krishnamurthy, Rod Giles
  • Technical Paper
  • 2019-32-0593
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
The forthcoming pass-by noise regulations have impacted the automotive sector, which further leads to the reduction of noise in the vehicle. The prediction of pass-by noise at an early stage will reduce the overall cost as well as time for an automobile industry and helps to reduce the overall product development life cycle. This supports the design activities of a vehicle.Msc ACTRAN/NASTRAN/ADAMS and GT Suite are major tools used in the present study to develop a simulation method to mimic the predefined testing norms. In Actran interior and exterior noise propagation is performed. Interior noise flow obtained by compressible flow analysis which uses exhaust/intake line velocity/temperature as boundary condition. The exterior noise propagation obtained by direct frequency response using acoustic duct mode with unit pressure injected into the intake and exhaust system and compressible flow field map results as input, this will take care of both noise propagation. Similarly for engine exterior noise radiation done by Nastran unit frequency response analysis and later actual loads from multi-body dynamics multiplied with direct frequency response analysis in…
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