Criteria

Text:
Display:

Results

Viewing 1 to 30 of 109910
2017-06-17
Journal Article
2017-01-9550
David Neihguk, M. L. Munjal, Arvind Ram, Abhinav Prasad
Abstract A production muffler of a 2.2 liter compression ignition engine is analyzed using plane wave (Transfer Matrix) method. The objective is to show the usefulness of plane wave models to analyze the acoustic performance (Transmission Loss, TL) of a compact hybrid muffler (made up of reactive and dissipative elements). The muffler consists of three chambers, two of which are acoustically short in the axial direction. The chambers are separated by an impervious baffle on the upstream side and a perforated plate on the downstream side. The first chamber is a Concentric Tube Resonator (CTR). The second chamber consists of an extended inlet and a flow reversal 180-degree curved outlet duct. The acoustic cavity in the third chamber is coupled with the second chamber through the acoustic impedances of the end plate and the perforated plate.
2017-06-05
Technical Paper
2017-01-1873
Stéphane Molla, Pierre Mollon, Patrick Boussard
Automotive starters are basically composed of a direct current electric engine, a reduction gear and a pinion clutching system over the ring of the combustion engine. Such a device can sometimes produce a high-frequency “whistling” sound, considered as unpleasant by the users. Because of the variability of the rotation speeds and the structural responses of the elements assembled by clamping, the audible frequencies of this sound are not always easy to identify. In the context of quality assessments in production lines, VALEO needs a reliable tool to detect and quantify the presence of this phenomenon with a method as non-intrusive as possible. A solution was found using an automatic component separation algorithm: tonal components are detected and extracted, allowing to estimate their contribution to the overall level with respect to the background noise. No tachometric measurement is required.
2017-06-05
Technical Paper
2017-01-1763
Lisa Steinbach, Ercan Altinsoy PhD, Robert Rosenkranz
In today's urban environment inhabitants are permanently exposed to elevated noise levels, which are mostly dominated by traffic noise. The current electrification of vehicles might affect the traffic noise in city centers. The aim of this work was to determine the pedestrian reaction and the annoyance of more realistic traffic situations. For this purpose both combustion and electric vehicle noise situations and mixed scenarios of both concepts were generated. The differences in the perceived annoyance were investigated with perception studies. It was found that in some cases the order of the annoyance ratings will change: a single electric vehicle, which was perceived as least annoying, was evaluated as the most annoying noise by the increase to eight vehicles. The background noise also has an impact on the perception of annoyance and the warning effect.
2017-06-05
Technical Paper
2017-01-1788
Kishore Chand Ulli, Upender Rao Gade
Automotive window buffeting is a source of vehicle occupant's discomfort. Original equipment manufacturers (OEM) are using both experimental and numerical methods to address this problem. With both methods having their merits and demerits, the numerical method Computational Fluid Dynamics (CFD) is more often preferred by engineers as a tool of choice due its reliability & usefulness. With much advances in the computational power and numerical modelling it is now possible to investigate the influence of vehicle design on cabin interior noises ,even before building a prototype for testing. In the traditional aero-acoustic modelling direct turbulence model like Large Eddy Simulation (LES) is preferred to simulate the larger eddies responsible for much of acoustic excitation. But still LES is a computationally expensive methodology for a few automotive applications like Window Buffeting that involves complex geometries and larger domains.
2017-06-05
Technical Paper
2017-01-1752
Kapil Gupta, Rakesh Bidre, Arun Choudhary
At present, a Dual Mass Flywheel (DMF) system is widely known to provide benefits on driveline induced noise, vibration and drivability over a Single Mass Flywheel (SMF). A well-tuned DMF provides nice isolation of torsional vibrations generated in periodic combustion process of automobile IC engines. Similarly, a torsional vibration damper mounted on driveline component reduces the torsional excitation and results a lower torsional vibration at driveline components. Noise and vibration issues like boom noise and high vibrations at low engine rpm range drive are often resulted due to high engine firing order torsional excitation input to the driveline. More often, this becomes one of the most objectionable noise and vibration issues in vehicle and should be eliminated or reduced for better NVH performance. A 4 cylinder, 4 stroke small diesel engine equipped with SMF is found to have high engine firing order torsional excitation.
2017-06-05
Technical Paper
2017-01-1754
Kyoung-Jin Chang, Seonghyeon Kim, Dong Chul Park, So Youn Moon, Sunghwan Park, Myung Hwan Yun
This paper aims to establish a systematic process of developing a brand driving sound. First, the representative auditory terminology suitable to expressing the brand sound is induced and then the principal factors of a brand sound are extracted from factor analysis. As a result, brand sound positioning map is drawn using jury test data. Secondly, the multiple regression analysis of subjective and objective test results are carried out and then brand sound positioning map is re-drawn using measurement data and the correlation results of subjective and objective test. Drawing a brand sound positioning map with only measurement data is more helpful than with jury test data because it can be easily updated. Also, what should be improved for designing a target sound is reviewed. Thirdly, an efficient technology to design a target sound which involve brand identity and vehicle’s character is suggested.
2017-06-05
Technical Paper
2017-01-1757
Matthew Maunder, Benjamin Munday
Excitement, image and emotion are key attributes for cars, particularly those with higher power ratings. Engine sound has traditionally acted as the car’s voice, conveying these attributes to the driver and passengers along with the brand image. Engine sound also underpins the dynamic driving experience by giving instant feedback about how a car is operating, enhancing the connection between driver and vehicle. For decades, the automotive industry has engineered engine sound to achieve these benefits, thereby defining the ‘language’ of car sound. Electric vehicles deliver strong and responsive performance but naturally lack the acoustic feedback that internal combustion engines provide. While this gives advantages in terms of comfort and environmental noise, the benefits of engine sound are lost. Carefully controlled acoustic feedback brings tangible and valuable benefits both for the dynamic driving experience and to convey the brand image.
2017-06-05
Technical Paper
2017-01-1761
Daniel Fernandez Comesana, Graciano Carrillo Pousa
The automotive industry is currently increasing noise and vibration requirements of vehicle components. A detailed vibro-acoustic assessment of every supplied element is commonly enforced by most vehicle manufacturers. Traditional End-of-line (EOL) solutions often encounter difficulties adapting from controlled environments to industrial production lines due the presence of high levels of noise and vibrations generated by the surrounding machinery. In contrast, particle velocity measurements performed near a rigid radiating surface are less affected by background noise and they can potentially be used to address noise problems even in such conditions. The vector nature of particle velocity, an intrinsic dependency upon surface displacement and sensor directivity are the main advantages over conventional solutions. As a result, quantitative measurements describing the vibro-acoustic behaviour of a device can be performed at the final stage of the manufacturing process.
2017-06-05
Technical Paper
2017-01-1762
Michael Roan, M. Lucas Neurauter, Douglas Moore, Dan Glaser
Hybrid and electric vehicles (HVs and EVs) have demonstrated low noise levels relative to their Internal Combustion Engine (ICE) counterparts, particularly at low speeds. As the number of HVs/EVs on the road increases, so does the need for data quantifying auditory detectability by pedestrians; in particular, those who are vision impaired. Manufacturers have begun to implement additive noise solutions designed to increase vehicle detectability while in electric mode and/or when traveling below a certain speed. A detailed description of the real-time acoustic measurement system, the corresponding vehicular data, development of an immersive noise field, and experimental methods pertaining to a recent evaluation of candidate vehicles is provided herein. Listener testing was completed by 24 legally blind test subjects for four vehicle types: an EV and HV with different additive noise approaches, an EV with no additive noise, and a traditional ICE vehicle.
2017-06-05
Technical Paper
2017-01-1766
Dirk von Werne, Stefano Orlando, Anneleen Van Gils, Thierry Olbrechts, Ivan Bosmans
Methodology to secure cabin noise and vibration targets is presented. Early in the design process, typically in the Joint Definition Phase, Targets are cascaded from system to component level to comply to the overall cabin noise target in various load cases. During the Detailed Design Phase, 3D simulation models are build up to further secure and refine the vibro-acoustic performance of the cabin noise related subsystems. Noise sources are estimated for the target setting based on analytical and empirical expressions from literature. This includes various types of engine noise – fan, jet, and propeller noise – as well as turbulent boundary layer noise. For other noise sources, ECS and various auxiliaries, targets are set such as to ensure the overall cabin noise level. To synthesize the cabin noise, these noise sources are combined with estimates of the noise transfer through panels and the cavity effect of the cabin. This part is again based on analytical and empirical formulations.
2017-06-05
Technical Paper
2017-01-1771
Mohamed El morsy, Gabriela Achtenova
Gear fault diagnosis is important in the vibration monitoring of any rotating machine. When a localized fault occurs in gears, the vibration signals always display non-stationary behavior. In early stage of gear failure, the gear mesh frequency (GMF) contains very little energy and is often overwhelmed by noise and higher-level macro-structural vibrations. An effective signal processing method would be necessary to remove such corrupting noise and interference. This paper presents the value of optimal wavelet function for early detection of faulty gear. The Envelope Detection (ED) and the Energy Operator are used for gear fault diagnosis as common techniques with and without the proposed optimal wavelet to verify the effectiveness of the optimal wavelet function. Kurtosis values are determined for the previous techniques as an indicator parameter for the ability of early gear fault detection. The comparative study is applied to real vibration signals.
2017-06-05
Technical Paper
2017-01-1768
Yong Xu
Purpose: For rear-wheel-drive (or all-wheel-drive) vehicles, the vibration and noise that caused by driveshaft often become the main factors that influence the comfort level of vehicle. In order to control and improve the NVH problems related to driveshaft, this work aimed to study the excitation mechanism and transfer path of driveshaft vibration, and then to propose effective measures. The purpose of this work was to propose an effective way to improve the NVH performance by controlling the additional excitation force of U-joints in the early phase of project. Methodology: First, the rotation order characteristics of driveshaft were studied with the aid of classical dynamics. Then a rigid-elastic coupling model of vehicle powertrain was modelled with the theory of multi-body dynamics. By inputting the actual vehicle parameters into the model, the acceleration operation of vehicle could be simulated.
2017-06-05
Technical Paper
2017-01-1772
Yawen Wang, Teik Lim, Xuan Li, Guan Qiao
The prediction and control of gear vibration and noise has become very important in the design of a quiet, high-quality gearbox systems. The vibratory energy of the gear pair caused by transmission error excitation is transmitted structurally through shaft-bearing-housing assembly and radiates off from exterior housing surface. Most of the previous studies ignore the contribution of components flexibility to the transmission error. In this study, a system level model of axle system with hypoid gear pair is developed, aiming at investigating the effect of the elasticity of the shafts, bearings and housing. The load distribution results and gear transmission errors are calculated and compared between different assumptions on the boundary conditions. A series of parametric studies are also performed to analyze the effects of various shaft-bearing configurations and properties on the dynamic responses of the geared system.
2017-06-05
Technical Paper
2017-01-1775
Mark A. Gehringer
This paper describes recently developed test methods and instrumentation to address the specific noise and vibration measurement challenges posed by large diameter single-piece tubular aluminum propeller shafts with high modal density. The application described in this paper is a light duty truck, although the methods described are applicable to any rotating shaft with similar dynamic properties. To provide a practical example of the newly developed methods and instrumentation, rotating and non-rotating data were acquired in-situ for several propeller shafts of varying construction, including both lined and unlined shafts. Data were also acquired with and without a torsional tuned vibration absorber attached to the driveline. The example data exhibit features that are uniquely characteristic of large diameter single-piece tubular shafts with high modal density, including the particular effect of shaft rotation on the measurements.
2017-06-05
Technical Paper
2017-01-1777
Thomas Wellmann, Kiran Govindswamy, Dean Tomazic
The automotive industry continues to develop new technologies aimed at reducing overall vehi-cle level fuel consumption. Powertrain and driveline related technologies will play a key role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. Specifically, use of tech-nologies such as downsized engines, idle start-stop systems, aggressive torque converter lock-up schedules, wide-ratio spread transmissions, and electrified propulsion systems are vital to-wards meeting aggressive fuel economy targets. Judicious combinations of such powertrain and driveline technology packages in conjunction with measures such as the use of low rolling resistance tires and vehicle lightweighting will be required to meet future OEM fleet CO2 targets. Many of the technologies needed for meeting the fuel economy and CO2 targets come with unique NVH challenges. In order to ensure customer acceptance of new vehicles, it is impera-tive that these NVH challenges be understood and solved.
2017-06-05
Technical Paper
2017-01-1778
Enrico Galvagno, Antonio Tota PhD, Alessandro Vigliani, Mauro Velardocchia
This paper explores the potentiality of reducing noise and vibration of a vehicle transmission thanks to powertrain control integration with active braking system. The torsional backlashes between transmission rotating components (gears, synchronizers, splines, CV joints), in the presence of external disturbances, coming from the driver, e.g. during tip-in / tip-out maneuvers, or from the road, e.g. crossing a speed bump or driving on a rough road, may lead to NVH issues known as clonk. In this study, first of all the positive effect of a brake torque application at the driving wheels during such maneuvers on transmission NVH performance is shown. After that, a powertrain/brake integrated control strategy is proposed. The braking system is activated in advance with respect to the perturbation and it is deactivated immediately after to minimize the energy loss.
2017-06-05
Technical Paper
2017-01-1779
Xianwu yang, Jian Pang, Lanjun WANG, Xiong tian, Yu Tang
With the development of automobile industry, the higher NVH performance is required for customers, and with drastically reduction of engine noise, the gear rattle noise generated by the impact between neutral gears inside transmission can be much easily perceived. It is well known that the torsional mode of powertrain system has a direct relationship with transmission gear rattle noise, the higher torsional vibration leads to more serious gear rattle noise. This paper establishes a torsional model of a front wheel drive automotive drivetrain, including clutch system, transmission box and equivalent load of a full vehicle in AMESim software. The experimental engine speed fluctuations at different gears are used to excite the torsional model.
2017-06-05
Technical Paper
2017-01-1781
Joshua Wheeler
Automatic Speech Recognition (ASR) and Hands Free Communication (HFC) capabilities have become prominent in the automotive industry, with over 50% of new vehicle sales equipped with some level of ASR system. With the common use of mobile personal assistants and smartphones with Bluetooth capability, customer expectations for built in ASR and HFC systems have increased significantly. The performance of these ASR and HFC systems are highly dependent on the level of background or “masking” noise that competes with the speech engine’s ability to correctly convert the driver’s speech to actionable commands. HVAC noise provides high amplitudes of broadband frequency content that affects the signal to noise ratio (SNR) within the vehicle cabin, and works to mask the user’s speech. Furthermore, when the airflow from the panel or defroster vents are directed toward the vehicle microphone, a mechanical “buffeting” phenomenon occurs that distresses the ASR system even further.
2017-06-05
Technical Paper
2017-01-1783
Chris Todter, Paul Bremner, Olivier Robin, Christophe Marchetto, Alain Berry
Fluctuating surface pressure measurements using microphone arrays are still challenging, especially in an automotive context with cruising speeds around Mach 0.1. The separated turbulent boundary layer excitation and the side mirror wake flow generate both acoustic and aerodynamic components, which have wavenumbers that differ by a factor of approximately 10. This calls for high spatial resolution measurements to fully resolve the wavenumber-frequency spectrum. In SAE paper 2015-01-2325, the authors reported a micro-electro-mechanical (MEMS) surface microphone array that successfully used wavenumber analysis to quantify acoustic versus turbulence loading. It was shown that the measured surface pressure at each microphone could be strongly influenced by self noise induced by the microphone ”packaging”, which can be attenuated with a suitable windscreen.
2017-06-05
Technical Paper
2017-01-1786
Hiroshi Yokoyama, Ryo Adachi, Taiki Minato, Akiyoshi Iida
Intense tonal sound often radiates from flows around a cavity such as a sunroof or various gaps between parts of automobiles, and this sound is referred to as cavity tone. This cavity tone is due to fluid-acoustic interactions in cavity flows, where a vortex impinging at the downstream wall generates an acoustic wave and the acoustic wave propagating in the upstream direction induces another vortex near the upstream edge. The control of the cavity tone by blowing jets into the oncoming boundary layer is focused on. Moreover, the effects of the spanwise pitch of the jets on the flow and acoustic fields were investigated. To clarify the control effects on the cavity flow and tone, both low-noise wind tunnel experiments and direct aeroacoustic simulations based on the compressible Navier-Stokes equations were performed. Main experiments and computations were performed at the freestream Mach number of 0.09, where the oncoming boundary layer is laminar.
2017-06-05
Technical Paper
2017-01-1785
Paul Bremner, Scott Clifton, Chris Todter
Measurements of interior wind noise sound pressure level have shown that dBA and Loudness are not adequate metrics of wind noise sound quality due to non-stationary characteristics such as temporal modulation and impulse. A surface microphone array with high spatio-temporal resolution has been used to observe the corresponding non-stationary characteristics of the exterior aero-acoustic loading. Wavenumber filtering is used to observe the unsteady character of the low wavenumber aero-acoustic loading components capable of exciting glass vibration and transmitting sound.
2017-06-05
Technical Paper
2017-01-1791
David Neihguk, Shreyas Fulkar
The acoustic and back pressure performance of a production hybrid (made up of reactive and dissipative elements) muffler for tractor application is analyzed using the Integrated Transfer Matrix Method (ITM) and the flow resistance network method, respectively. The twin objectives of the present work consist of the development of a validated 1D analytical model of the muffler and the creation of a generic application with a user friendly interface using an enterprise level calculations management tool. This enables designers to explore various design options in the early design phase. The acoustic and back pressure performance of the muffler are validated with both 1D (GT-SUITE) and 3D FEM (COMSOL) commercial tools. The transmission loss is simulated with and without flow as well as with and without glasswool. The accuracy of the 1D and 3D models are firstly verified with the results obtained from published literature.
2017-06-05
Technical Paper
2017-01-1790
Vinayak H. Patil, Ravi Kumar sara, T. R. Milind, Rodney C. Glover
Vehicle noise emission regulations are becoming more stringent each passing year (e.g. pass-by noise requirement for passenger vehicles is now 74 dB(A) in some parts of the world). The common focus areas for noise treatment in the vehicle are primarily on three sub-systems i.e., engine compartment, exhaust systems and power train systems. Down- sizing and down- speeding of engines without compromising on power output has meant use of boosting technologies that have produced challenges to design low-noise intake systems minimizing losses and meeting today’s vehicle emission regulations. There are multiple sources of noise in an intake system. Thus an understanding of the sources of noise in the intake system is needed. One such boosting system consists of Turbo-Super configuration with elements like air box filter, outlet manifold and intercooler.
2017-06-05
Technical Paper
2017-01-1793
William Seldon, Amer Shoeb, Daniel Schimmel, Jared Cromas
As regulations become increasing stringent and customer expectations of vehicle refinement increase the accurate control and prediction of the air induction system (AIS) and exhaust system airborne acoustics are a critical factor in creating a vehicle that wins in the marketplace. The team selected two projects to highlight for SAE. This paper will explore the details of an exhaust focused correlation project that was performed on a naturally aspirated eight cylinder engine. While the other SAE paper (XX-XX-XX) focus on correlation of an induction system on a turbocharged four cylinder.
2017-06-05
Technical Paper
2017-01-1792
Magnus Knutsson, Erik Kjellson, Rodney Glover, Hans Boden
Increased demands for reduction of fuel consumption and CO2 emissions are driven by the global warming. To meet these challenges with respect to the passenger car segment the strategy of utilizing IC-engine downsizing has shown to be effective. In order to additionally meet requirements for high power and low end torque output supercharging is required. This can be realized using e.g. turbo-chargers, roots blowers or a combination of several such devices for the highest specific power segment. Both turbo-chargers and roots blowers can be strong sources of sound depending on the operating conditions and extensive NVH abatements such as resonators and encapsulation might be required to achieve superior vehicle NVH. For an efficient resonator tuning process in-duct acoustic source data is required. No published studies exists that describe how the gas exchange process for roots blowers can be described by acoustic sources in the frequency domain.
2017-06-05
Technical Paper
2017-01-1794
William Seldon, Jamie Hamilton, Jared Cromas, Daniel Schimmel
Abstract As regulations become increasing stringent and customer expectations of vehicle refinement increase the accurate control and prediction of the air induction system (AIS) and exhaust system airborne acoustics are a critical factor in creating a vehicle that wins in the marketplace. The team selected two projects to highlight for SAE. This paper will explore the details of an induction focused correlation project that was performed on a turbocharged four cylinder engine. The other SAE paper (XX-XX-XX) will focus on the correlation of an exhaust system on a naturally aspirated eight cylinder.
2017-06-05
Technical Paper
2017-01-1798
Jiri Navratil, Warren Seeley, Shriram Siravara, Peng Wang
The ability to predict exhaust system acoustics including transmission loss (TL) and tailpipe noise accurately based on CAD geometry has long been a requirement of most OEM’s and Tier 1 exhaust suppliers. Correlation to measurement data has been problematic under various operating conditions including flow. This study was undertaken to address and identify the critical dimensions and modeling sensitivities. Ford uses Ricardo WAVE as one of their 1-D NVH tools, which was chosen for the purpose of this benchmark study. The vibro-acoustics group at University of Kentucky Department of Mechanical Engineering (UKME) has extensive experience in using 3D and 1D acoustic modeling tools for exhaust components and in correlating the numerical predictions to measurements. The most commonly used metrics for evaluating the acoustical performance of mufflers are insertion loss (IL), transmission loss (TL), and noise reduction (NR).
2017-06-05
Technical Paper
2017-01-1797
Adrien Mann, Raj Nair, Jesse Gill, Brett Birschbach, Patrick Crowley
One of the major drawbacks of combustion engines is their combustion noise. To mitigate this issue, exhaust systems including mufflers are commonly mounted on engines. As community noise and work environment regulations become increasingly more stringent, engine and muffler manufacturers must keep improving the acoustic performances of their products. While the main purpose of this system is to reduce the intensity of engine orders, the induced back pressure must be kept minimum to guarantee optimal engine operating conditions. Achieving such performances, however, implies the increasing complexity of muffler designs, often leading to the emergence of undesired noise produced by the flow circulating inside a muffler, or muffler self-noise. Addressing those issues early in the development process using an experimental process based on prototyping can be complex, time-consuming and expensive. Numerical approaches are an alternative.
2017-06-05
Technical Paper
2017-01-1803
John Van Baren
The accumulated damage that a product experiences in the field due to the variety of vibration stresses placed upon it will eventually cause failures in the product. The failure modes resulting from these dynamic stresses can be replicated in the laboratory and correlated to end use environment to validate target reliability requirements. This presentation addresses three fundamental questions about developing accelerated random vibration stress tests. Question#1: What random profile is needed (and for how much time) to accurately simulate the end use environment over the life-cycle of my product? Question #2: My product operates in many different vibration environments, how can I confidently combine them into one accelerated test?Question #3: How can I use the FDS to accelerate my test?
2017-06-05
Technical Paper
2017-01-1805
Krzysztof Prażnowski, Jaroslaw Mamala
The vibrations of the sprung mass of a passenger car, traveling on a road surface, are random and are its main source but not the only one. The resulting force ratio is further confounded by other factors occurring at the interface of the pneumatic tire with the road surface, such as non-uniformity of tires, errors shape and imbalances. The resulting the additional inertia force acts on the previously brought kinematic force acting on the car body. Occurring at the time of the sprung mass vibrations of the car body can be treated as a potential source of diagnostic information, but their direct identification is difficult. Moreover, all basic identification is complicated by force derived from random interference unevenness in the road. Then the ratio defined as SNR accepts negative values. Due to the lack of description in the literature conclusive research to identify the unbalance the whole pneumatic wheel real conditions, conducted its own experimental research.
Viewing 1 to 30 of 109910

Filter

  • Range:
    to:
  • Year: